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[cascardo/linux.git] / fs / xfs / xfs_inode.c

/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include <linux/log2.h>

#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_dir2.h"
#include "xfs_attr_sf.h"
#include "xfs_attr.h"
#include "xfs_trans_space.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"
#include "xfs_inode_item.h"
#include "xfs_ialloc.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_error.h"
#include "xfs_quota.h"
#include "xfs_filestream.h"
#include "xfs_cksum.h"
#include "xfs_trace.h"
#include "xfs_icache.h"
#include "xfs_symlink.h"
#include "xfs_trans_priv.h"
#include "xfs_log.h"
#include "xfs_bmap_btree.h"

kmem_zone_t *xfs_inode_zone;

/*
 * Used in xfs_itruncate_extents().  This is the maximum number of extents
 * freed from a file in a single transaction.
 */
#define XFS_ITRUNC_MAX_EXTENTS  2

STATIC int xfs_iflush_int(xfs_inode_t *, xfs_buf_t *);

STATIC int xfs_iunlink_remove(xfs_trans_t *, xfs_inode_t *);

/*
 * helper function to extract extent size hint from inode
 */
xfs_extlen_t
xfs_get_extsz_hint(
        struct xfs_inode        *ip)
{
        if ((ip->i_d.di_flags & XFS_DIFLAG_EXTSIZE) && ip->i_d.di_extsize)
                return ip->i_d.di_extsize;
        if (XFS_IS_REALTIME_INODE(ip))
                return ip->i_mount->m_sb.sb_rextsize;
        return 0;
}

/*
 * These two are wrapper routines around the xfs_ilock() routine used to
 * centralize some grungy code.  They are used in places that wish to lock the
 * inode solely for reading the extents.  The reason these places can't just
 * call xfs_ilock(ip, XFS_ILOCK_SHARED) is that the inode lock also guards to
 * bringing in of the extents from disk for a file in b-tree format.  If the
 * inode is in b-tree format, then we need to lock the inode exclusively until
 * the extents are read in.  Locking it exclusively all the time would limit
 * our parallelism unnecessarily, though.  What we do instead is check to see
 * if the extents have been read in yet, and only lock the inode exclusively
 * if they have not.
 *
 * The functions return a value which should be given to the corresponding
 * xfs_iunlock() call.
 */
uint
xfs_ilock_data_map_shared(
        struct xfs_inode        *ip)
{
        uint                    lock_mode = XFS_ILOCK_SHARED;

        if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE &&
            (ip->i_df.if_flags & XFS_IFEXTENTS) == 0)
                lock_mode = XFS_ILOCK_EXCL;
        xfs_ilock(ip, lock_mode);
        return lock_mode;
}

uint
xfs_ilock_attr_map_shared(
        struct xfs_inode        *ip)
{
        uint                    lock_mode = XFS_ILOCK_SHARED;

        if (ip->i_d.di_aformat == XFS_DINODE_FMT_BTREE &&
            (ip->i_afp->if_flags & XFS_IFEXTENTS) == 0)
                lock_mode = XFS_ILOCK_EXCL;
        xfs_ilock(ip, lock_mode);
        return lock_mode;
}

/*
 * The xfs inode contains 2 locks: a multi-reader lock called the
 * i_iolock and a multi-reader lock called the i_lock.  This routine
 * allows either or both of the locks to be obtained.
 *
 * The 2 locks should always be ordered so that the IO lock is
 * obtained first in order to prevent deadlock.
 *
 * ip -- the inode being locked
 * lock_flags -- this parameter indicates the inode's locks
 *       to be locked.  It can be:
 *              XFS_IOLOCK_SHARED,
 *              XFS_IOLOCK_EXCL,
 *              XFS_ILOCK_SHARED,
 *              XFS_ILOCK_EXCL,
 *              XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED,
 *              XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL,
 *              XFS_IOLOCK_EXCL | XFS_ILOCK_SHARED,
 *              XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
 */
void
xfs_ilock(
        xfs_inode_t             *ip,
        uint                    lock_flags)
{
        trace_xfs_ilock(ip, lock_flags, _RET_IP_);

        /*
         * You can't set both SHARED and EXCL for the same lock,
         * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
         * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
         */
        ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
               (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
        ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
               (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
        ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);

        if (lock_flags & XFS_IOLOCK_EXCL)
                mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
        else if (lock_flags & XFS_IOLOCK_SHARED)
                mraccess_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));

        if (lock_flags & XFS_ILOCK_EXCL)
                mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
        else if (lock_flags & XFS_ILOCK_SHARED)
                mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
}

/*
 * This is just like xfs_ilock(), except that the caller
 * is guaranteed not to sleep.  It returns 1 if it gets
 * the requested locks and 0 otherwise.  If the IO lock is
 * obtained but the inode lock cannot be, then the IO lock
 * is dropped before returning.
 *
 * ip -- the inode being locked
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be locked.  See the comment for xfs_ilock() for a list
 *       of valid values.
 */
int
xfs_ilock_nowait(
        xfs_inode_t             *ip,
        uint                    lock_flags)
{
        trace_xfs_ilock_nowait(ip, lock_flags, _RET_IP_);

        /*
         * You can't set both SHARED and EXCL for the same lock,
         * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
         * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
         */
        ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
               (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
        ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
               (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
        ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);

        if (lock_flags & XFS_IOLOCK_EXCL) {
                if (!mrtryupdate(&ip->i_iolock))
                        goto out;
        } else if (lock_flags & XFS_IOLOCK_SHARED) {
                if (!mrtryaccess(&ip->i_iolock))
                        goto out;
        }
        if (lock_flags & XFS_ILOCK_EXCL) {
                if (!mrtryupdate(&ip->i_lock))
                        goto out_undo_iolock;
        } else if (lock_flags & XFS_ILOCK_SHARED) {
                if (!mrtryaccess(&ip->i_lock))
                        goto out_undo_iolock;
        }
        return 1;

 out_undo_iolock:
        if (lock_flags & XFS_IOLOCK_EXCL)
                mrunlock_excl(&ip->i_iolock);
        else if (lock_flags & XFS_IOLOCK_SHARED)
                mrunlock_shared(&ip->i_iolock);
 out:
        return 0;
}

/*
 * xfs_iunlock() is used to drop the inode locks acquired with
 * xfs_ilock() and xfs_ilock_nowait().  The caller must pass
 * in the flags given to xfs_ilock() or xfs_ilock_nowait() so
 * that we know which locks to drop.
 *
 * ip -- the inode being unlocked
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be unlocked.  See the comment for xfs_ilock() for a list
 *       of valid values for this parameter.
 *
 */
void
xfs_iunlock(
        xfs_inode_t             *ip,
        uint                    lock_flags)
{
        /*
         * You can't set both SHARED and EXCL for the same lock,
         * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
         * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
         */
        ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
               (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
        ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
               (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
        ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
        ASSERT(lock_flags != 0);

        if (lock_flags & XFS_IOLOCK_EXCL)
                mrunlock_excl(&ip->i_iolock);
        else if (lock_flags & XFS_IOLOCK_SHARED)
                mrunlock_shared(&ip->i_iolock);

        if (lock_flags & XFS_ILOCK_EXCL)
                mrunlock_excl(&ip->i_lock);
        else if (lock_flags & XFS_ILOCK_SHARED)
                mrunlock_shared(&ip->i_lock);

        trace_xfs_iunlock(ip, lock_flags, _RET_IP_);
}

/*
 * give up write locks.  the i/o lock cannot be held nested
 * if it is being demoted.
 */
void
xfs_ilock_demote(
        xfs_inode_t             *ip,
        uint                    lock_flags)
{
        ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL));
        ASSERT((lock_flags & ~(XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);

        if (lock_flags & XFS_ILOCK_EXCL)
                mrdemote(&ip->i_lock);
        if (lock_flags & XFS_IOLOCK_EXCL)
                mrdemote(&ip->i_iolock);

        trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
}

#if defined(DEBUG) || defined(XFS_WARN)
int
xfs_isilocked(
        xfs_inode_t             *ip,
        uint                    lock_flags)
{
        if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
                if (!(lock_flags & XFS_ILOCK_SHARED))
                        return !!ip->i_lock.mr_writer;
                return rwsem_is_locked(&ip->i_lock.mr_lock);
        }

        if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
                if (!(lock_flags & XFS_IOLOCK_SHARED))
                        return !!ip->i_iolock.mr_writer;
                return rwsem_is_locked(&ip->i_iolock.mr_lock);
        }

        ASSERT(0);
        return 0;
}
#endif

#ifdef DEBUG
int xfs_locked_n;
int xfs_small_retries;
int xfs_middle_retries;
int xfs_lots_retries;
int xfs_lock_delays;
#endif

/*
 * Bump the subclass so xfs_lock_inodes() acquires each lock with
 * a different value
 */
static inline int
xfs_lock_inumorder(int lock_mode, int subclass)
{
        if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
                lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_IOLOCK_SHIFT;
        if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL))
                lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_ILOCK_SHIFT;

        return lock_mode;
}

/*
 * The following routine will lock n inodes in exclusive mode.
 * We assume the caller calls us with the inodes in i_ino order.
 *
 * We need to detect deadlock where an inode that we lock
 * is in the AIL and we start waiting for another inode that is locked
 * by a thread in a long running transaction (such as truncate). This can
 * result in deadlock since the long running trans might need to wait
 * for the inode we just locked in order to push the tail and free space
 * in the log.
 */
void
xfs_lock_inodes(
        xfs_inode_t     **ips,
        int             inodes,
        uint            lock_mode)
{
        int             attempts = 0, i, j, try_lock;
        xfs_log_item_t  *lp;

        ASSERT(ips && (inodes >= 2)); /* we need at least two */

        try_lock = 0;
        i = 0;

again:
        for (; i < inodes; i++) {
                ASSERT(ips[i]);

                if (i && (ips[i] == ips[i-1]))  /* Already locked */
                        continue;

                /*
                 * If try_lock is not set yet, make sure all locked inodes
                 * are not in the AIL.
                 * If any are, set try_lock to be used later.
                 */

                if (!try_lock) {
                        for (j = (i - 1); j >= 0 && !try_lock; j--) {
                                lp = (xfs_log_item_t *)ips[j]->i_itemp;
                                if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
                                        try_lock++;
                                }
                        }
                }

                /*
                 * If any of the previous locks we have locked is in the AIL,
                 * we must TRY to get the second and subsequent locks. If
                 * we can't get any, we must release all we have
                 * and try again.
                 */

                if (try_lock) {
                        /* try_lock must be 0 if i is 0. */
                        /*
                         * try_lock means we have an inode locked
                         * that is in the AIL.
                         */
                        ASSERT(i != 0);
                        if (!xfs_ilock_nowait(ips[i], xfs_lock_inumorder(lock_mode, i))) {
                                attempts++;

                                /*
                                 * Unlock all previous guys and try again.
                                 * xfs_iunlock will try to push the tail
                                 * if the inode is in the AIL.
                                 */

                                for(j = i - 1; j >= 0; j--) {

                                        /*
                                         * Check to see if we've already
                                         * unlocked this one.
                                         * Not the first one going back,
                                         * and the inode ptr is the same.
                                         */
                                        if ((j != (i - 1)) && ips[j] ==
                                                                ips[j+1])
                                                continue;

                                        xfs_iunlock(ips[j], lock_mode);
                                }

                                if ((attempts % 5) == 0) {
                                        delay(1); /* Don't just spin the CPU */
#ifdef DEBUG
                                        xfs_lock_delays++;
#endif
                                }
                                i = 0;
                                try_lock = 0;
                                goto again;
                        }
                } else {
                        xfs_ilock(ips[i], xfs_lock_inumorder(lock_mode, i));
                }
        }

#ifdef DEBUG
        if (attempts) {
                if (attempts < 5) xfs_small_retries++;
                else if (attempts < 100) xfs_middle_retries++;
                else xfs_lots_retries++;
        } else {
                xfs_locked_n++;
        }
#endif
}

/*
 * xfs_lock_two_inodes() can only be used to lock one type of lock
 * at a time - the iolock or the ilock, but not both at once. If
 * we lock both at once, lockdep will report false positives saying
 * we have violated locking orders.
 */
void
xfs_lock_two_inodes(
        xfs_inode_t             *ip0,
        xfs_inode_t             *ip1,
        uint                    lock_mode)
{
        xfs_inode_t             *temp;
        int                     attempts = 0;
        xfs_log_item_t          *lp;

        if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
                ASSERT((lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)) == 0);
        ASSERT(ip0->i_ino != ip1->i_ino);

        if (ip0->i_ino > ip1->i_ino) {
                temp = ip0;
                ip0 = ip1;
                ip1 = temp;
        }

 again:
        xfs_ilock(ip0, xfs_lock_inumorder(lock_mode, 0));

        /*
         * If the first lock we have locked is in the AIL, we must TRY to get
         * the second lock. If we can't get it, we must release the first one
         * and try again.
         */
        lp = (xfs_log_item_t *)ip0->i_itemp;
        if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
                if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(lock_mode, 1))) {
                        xfs_iunlock(ip0, lock_mode);
                        if ((++attempts % 5) == 0)
                                delay(1); /* Don't just spin the CPU */
                        goto again;
                }
        } else {
                xfs_ilock(ip1, xfs_lock_inumorder(lock_mode, 1));
        }
}


void
__xfs_iflock(
        struct xfs_inode        *ip)
{
        wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IFLOCK_BIT);
        DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IFLOCK_BIT);

        do {
                prepare_to_wait_exclusive(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
                if (xfs_isiflocked(ip))
                        io_schedule();
        } while (!xfs_iflock_nowait(ip));

        finish_wait(wq, &wait.wait);
}

STATIC uint
_xfs_dic2xflags(
        __uint16_t              di_flags)
{
        uint                    flags = 0;

        if (di_flags & XFS_DIFLAG_ANY) {
                if (di_flags & XFS_DIFLAG_REALTIME)
                        flags |= XFS_XFLAG_REALTIME;
                if (di_flags & XFS_DIFLAG_PREALLOC)
                        flags |= XFS_XFLAG_PREALLOC;
                if (di_flags & XFS_DIFLAG_IMMUTABLE)
                        flags |= XFS_XFLAG_IMMUTABLE;
                if (di_flags & XFS_DIFLAG_APPEND)
                        flags |= XFS_XFLAG_APPEND;
                if (di_flags & XFS_DIFLAG_SYNC)
                        flags |= XFS_XFLAG_SYNC;
                if (di_flags & XFS_DIFLAG_NOATIME)
                        flags |= XFS_XFLAG_NOATIME;
                if (di_flags & XFS_DIFLAG_NODUMP)
                        flags |= XFS_XFLAG_NODUMP;
                if (di_flags & XFS_DIFLAG_RTINHERIT)
                        flags |= XFS_XFLAG_RTINHERIT;
                if (di_flags & XFS_DIFLAG_PROJINHERIT)
                        flags |= XFS_XFLAG_PROJINHERIT;
                if (di_flags & XFS_DIFLAG_NOSYMLINKS)
                        flags |= XFS_XFLAG_NOSYMLINKS;
                if (di_flags & XFS_DIFLAG_EXTSIZE)
                        flags |= XFS_XFLAG_EXTSIZE;
                if (di_flags & XFS_DIFLAG_EXTSZINHERIT)
                        flags |= XFS_XFLAG_EXTSZINHERIT;
                if (di_flags & XFS_DIFLAG_NODEFRAG)
                        flags |= XFS_XFLAG_NODEFRAG;
                if (di_flags & XFS_DIFLAG_FILESTREAM)
                        flags |= XFS_XFLAG_FILESTREAM;
        }

        return flags;
}

uint
xfs_ip2xflags(
        xfs_inode_t             *ip)
{
        xfs_icdinode_t          *dic = &ip->i_d;

        return _xfs_dic2xflags(dic->di_flags) |
                                (XFS_IFORK_Q(ip) ? XFS_XFLAG_HASATTR : 0);
}

uint
xfs_dic2xflags(
        xfs_dinode_t            *dip)
{
        return _xfs_dic2xflags(be16_to_cpu(dip->di_flags)) |
                                (XFS_DFORK_Q(dip) ? XFS_XFLAG_HASATTR : 0);
}

/*
 * Lookups up an inode from "name". If ci_name is not NULL, then a CI match
 * is allowed, otherwise it has to be an exact match. If a CI match is found,
 * ci_name->name will point to a the actual name (caller must free) or
 * will be set to NULL if an exact match is found.
 */
int
xfs_lookup(
        xfs_inode_t             *dp,
        struct xfs_name         *name,
        xfs_inode_t             **ipp,
        struct xfs_name         *ci_name)
{
        xfs_ino_t               inum;
        int                     error;
        uint                    lock_mode;

        trace_xfs_lookup(dp, name);

        if (XFS_FORCED_SHUTDOWN(dp->i_mount))
                return -EIO;

        lock_mode = xfs_ilock_data_map_shared(dp);
        error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
        xfs_iunlock(dp, lock_mode);

        if (error)
                goto out;

        error = xfs_iget(dp->i_mount, NULL, inum, 0, 0, ipp);
        if (error)
                goto out_free_name;

        return 0;

out_free_name:
        if (ci_name)
                kmem_free(ci_name->name);
out:
        *ipp = NULL;
        return error;
}

/*
 * Allocate an inode on disk and return a copy of its in-core version.
 * The in-core inode is locked exclusively.  Set mode, nlink, and rdev
 * appropriately within the inode.  The uid and gid for the inode are
 * set according to the contents of the given cred structure.
 *
 * Use xfs_dialloc() to allocate the on-disk inode. If xfs_dialloc()
 * has a free inode available, call xfs_iget() to obtain the in-core
 * version of the allocated inode.  Finally, fill in the inode and
 * log its initial contents.  In this case, ialloc_context would be
 * set to NULL.
 *
 * If xfs_dialloc() does not have an available inode, it will replenish
 * its supply by doing an allocation. Since we can only do one
 * allocation within a transaction without deadlocks, we must commit
 * the current transaction before returning the inode itself.
 * In this case, therefore, we will set ialloc_context and return.
 * The caller should then commit the current transaction, start a new
 * transaction, and call xfs_ialloc() again to actually get the inode.
 *
 * To ensure that some other process does not grab the inode that
 * was allocated during the first call to xfs_ialloc(), this routine
 * also returns the [locked] bp pointing to the head of the freelist
 * as ialloc_context.  The caller should hold this buffer across
 * the commit and pass it back into this routine on the second call.
 *
 * If we are allocating quota inodes, we do not have a parent inode
 * to attach to or associate with (i.e. pip == NULL) because they
 * are not linked into the directory structure - they are attached
 * directly to the superblock - and so have no parent.
 */
int
xfs_ialloc(
        xfs_trans_t     *tp,
        xfs_inode_t     *pip,
        umode_t         mode,
        xfs_nlink_t     nlink,
        xfs_dev_t       rdev,
        prid_t          prid,
        int             okalloc,
        xfs_buf_t       **ialloc_context,
        xfs_inode_t     **ipp)
{
        struct xfs_mount *mp = tp->t_mountp;
        xfs_ino_t       ino;
        xfs_inode_t     *ip;
        uint            flags;
        int             error;
        struct timespec tv;

        /*
         * Call the space management code to pick
         * the on-disk inode to be allocated.
         */
        error = xfs_dialloc(tp, pip ? pip->i_ino : 0, mode, okalloc,
                            ialloc_context, &ino);
        if (error)
                return error;
        if (*ialloc_context || ino == NULLFSINO) {
                *ipp = NULL;
                return 0;
        }
        ASSERT(*ialloc_context == NULL);

        /*
         * Get the in-core inode with the lock held exclusively.
         * This is because we're setting fields here we need
         * to prevent others from looking at until we're done.
         */
        error = xfs_iget(mp, tp, ino, XFS_IGET_CREATE,
                         XFS_ILOCK_EXCL, &ip);
        if (error)
                return error;
        ASSERT(ip != NULL);

        /*
         * We always convert v1 inodes to v2 now - we only support filesystems
         * with >= v2 inode capability, so there is no reason for ever leaving
         * an inode in v1 format.
         */
        if (ip->i_d.di_version == 1)
                ip->i_d.di_version = 2;

        ip->i_d.di_mode = mode;
        ip->i_d.di_onlink = 0;
        ip->i_d.di_nlink = nlink;
        ASSERT(ip->i_d.di_nlink == nlink);
        ip->i_d.di_uid = xfs_kuid_to_uid(current_fsuid());
        ip->i_d.di_gid = xfs_kgid_to_gid(current_fsgid());
        xfs_set_projid(ip, prid);
        memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));

        if (pip && XFS_INHERIT_GID(pip)) {
                ip->i_d.di_gid = pip->i_d.di_gid;
                if ((pip->i_d.di_mode & S_ISGID) && S_ISDIR(mode)) {
                        ip->i_d.di_mode |= S_ISGID;
                }
        }

        /*
         * If the group ID of the new file does not match the effective group
         * ID or one of the supplementary group IDs, the S_ISGID bit is cleared
         * (and only if the irix_sgid_inherit compatibility variable is set).
         */
        if ((irix_sgid_inherit) &&
            (ip->i_d.di_mode & S_ISGID) &&
            (!in_group_p(xfs_gid_to_kgid(ip->i_d.di_gid)))) {
                ip->i_d.di_mode &= ~S_ISGID;
        }

        ip->i_d.di_size = 0;
        ip->i_d.di_nextents = 0;
        ASSERT(ip->i_d.di_nblocks == 0);

        tv = current_fs_time(mp->m_super);
        ip->i_d.di_mtime.t_sec = (__int32_t)tv.tv_sec;
        ip->i_d.di_mtime.t_nsec = (__int32_t)tv.tv_nsec;
        ip->i_d.di_atime = ip->i_d.di_mtime;
        ip->i_d.di_ctime = ip->i_d.di_mtime;

        /*
         * di_gen will have been taken care of in xfs_iread.
         */
        ip->i_d.di_extsize = 0;
        ip->i_d.di_dmevmask = 0;
        ip->i_d.di_dmstate = 0;
        ip->i_d.di_flags = 0;

        if (ip->i_d.di_version == 3) {
                ASSERT(ip->i_d.di_ino == ino);
                ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid));
                ip->i_d.di_crc = 0;
                ip->i_d.di_changecount = 1;
                ip->i_d.di_lsn = 0;
                ip->i_d.di_flags2 = 0;
                memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
                ip->i_d.di_crtime = ip->i_d.di_mtime;
        }


        flags = XFS_ILOG_CORE;
        switch (mode & S_IFMT) {
        case S_IFIFO:
        case S_IFCHR:
        case S_IFBLK:
        case S_IFSOCK:
                ip->i_d.di_format = XFS_DINODE_FMT_DEV;
                ip->i_df.if_u2.if_rdev = rdev;
                ip->i_df.if_flags = 0;
                flags |= XFS_ILOG_DEV;
                break;
        case S_IFREG:
        case S_IFDIR:
                if (pip && (pip->i_d.di_flags & XFS_DIFLAG_ANY)) {
                        uint    di_flags = 0;

                        if (S_ISDIR(mode)) {
                                if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
                                        di_flags |= XFS_DIFLAG_RTINHERIT;
                                if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
                                        di_flags |= XFS_DIFLAG_EXTSZINHERIT;
                                        ip->i_d.di_extsize = pip->i_d.di_extsize;
                                }
                                if (pip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
                                        di_flags |= XFS_DIFLAG_PROJINHERIT;
                        } else if (S_ISREG(mode)) {
                                if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
                                        di_flags |= XFS_DIFLAG_REALTIME;
                                if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
                                        di_flags |= XFS_DIFLAG_EXTSIZE;
                                        ip->i_d.di_extsize = pip->i_d.di_extsize;
                                }
                        }
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NOATIME) &&
                            xfs_inherit_noatime)
                                di_flags |= XFS_DIFLAG_NOATIME;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NODUMP) &&
                            xfs_inherit_nodump)
                                di_flags |= XFS_DIFLAG_NODUMP;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_SYNC) &&
                            xfs_inherit_sync)
                                di_flags |= XFS_DIFLAG_SYNC;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) &&
                            xfs_inherit_nosymlinks)
                                di_flags |= XFS_DIFLAG_NOSYMLINKS;
                        if ((pip->i_d.di_flags & XFS_DIFLAG_NODEFRAG) &&
                            xfs_inherit_nodefrag)
                                di_flags |= XFS_DIFLAG_NODEFRAG;
                        if (pip->i_d.di_flags & XFS_DIFLAG_FILESTREAM)
                                di_flags |= XFS_DIFLAG_FILESTREAM;
                        ip->i_d.di_flags |= di_flags;
                }
                /* FALLTHROUGH */
        case S_IFLNK:
                ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
                ip->i_df.if_flags = XFS_IFEXTENTS;
                ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
                ip->i_df.if_u1.if_extents = NULL;
                break;
        default:
                ASSERT(0);
        }
        /*
         * Attribute fork settings for new inode.
         */
        ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
        ip->i_d.di_anextents = 0;

        /*
         * Log the new values stuffed into the inode.
         */
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
        xfs_trans_log_inode(tp, ip, flags);

        /* now that we have an i_mode we can setup inode ops and unlock */
        xfs_setup_inode(ip);

        *ipp = ip;
        return 0;
}

/*
 * Allocates a new inode from disk and return a pointer to the
 * incore copy. This routine will internally commit the current
 * transaction and allocate a new one if the Space Manager needed
 * to do an allocation to replenish the inode free-list.
 *
 * This routine is designed to be called from xfs_create and
 * xfs_create_dir.
 *
 */
int
xfs_dir_ialloc(
        xfs_trans_t     **tpp,          /* input: current transaction;
                                           output: may be a new transaction. */
        xfs_inode_t     *dp,            /* directory within whose allocate
                                           the inode. */
        umode_t         mode,
        xfs_nlink_t     nlink,
        xfs_dev_t       rdev,
        prid_t          prid,           /* project id */
        int             okalloc,        /* ok to allocate new space */
        xfs_inode_t     **ipp,          /* pointer to inode; it will be
                                           locked. */
        int             *committed)

{
        xfs_trans_t     *tp;
        xfs_trans_t     *ntp;
        xfs_inode_t     *ip;
        xfs_buf_t       *ialloc_context = NULL;
        int             code;
        void            *dqinfo;
        uint            tflags;

        tp = *tpp;
        ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);

        /*
         * xfs_ialloc will return a pointer to an incore inode if
         * the Space Manager has an available inode on the free
         * list. Otherwise, it will do an allocation and replenish
         * the freelist.  Since we can only do one allocation per
         * transaction without deadlocks, we will need to commit the
         * current transaction and start a new one.  We will then
         * need to call xfs_ialloc again to get the inode.
         *
         * If xfs_ialloc did an allocation to replenish the freelist,
         * it returns the bp containing the head of the freelist as
         * ialloc_context. We will hold a lock on it across the
         * transaction commit so that no other process can steal
         * the inode(s) that we've just allocated.
         */
        code = xfs_ialloc(tp, dp, mode, nlink, rdev, prid, okalloc,
                          &ialloc_context, &ip);

        /*
         * Return an error if we were unable to allocate a new inode.
         * This should only happen if we run out of space on disk or
         * encounter a disk error.
         */
        if (code) {
                *ipp = NULL;
                return code;
        }
        if (!ialloc_context && !ip) {
                *ipp = NULL;
                return -ENOSPC;
        }

        /*
         * If the AGI buffer is non-NULL, then we were unable to get an
         * inode in one operation.  We need to commit the current
         * transaction and call xfs_ialloc() again.  It is guaranteed
         * to succeed the second time.
         */
        if (ialloc_context) {
                struct xfs_trans_res tres;

                /*
                 * Normally, xfs_trans_commit releases all the locks.
                 * We call bhold to hang on to the ialloc_context across
                 * the commit.  Holding this buffer prevents any other
                 * processes from doing any allocations in this
                 * allocation group.
                 */
                xfs_trans_bhold(tp, ialloc_context);
                /*
                 * Save the log reservation so we can use
                 * them in the next transaction.
                 */
                tres.tr_logres = xfs_trans_get_log_res(tp);
                tres.tr_logcount = xfs_trans_get_log_count(tp);

                /*
                 * We want the quota changes to be associated with the next
                 * transaction, NOT this one. So, detach the dqinfo from this
                 * and attach it to the next transaction.
                 */
                dqinfo = NULL;
                tflags = 0;
                if (tp->t_dqinfo) {
                        dqinfo = (void *)tp->t_dqinfo;
                        tp->t_dqinfo = NULL;
                        tflags = tp->t_flags & XFS_TRANS_DQ_DIRTY;
                        tp->t_flags &= ~(XFS_TRANS_DQ_DIRTY);
                }

                ntp = xfs_trans_dup(tp);
                code = xfs_trans_commit(tp, 0);
                tp = ntp;
                if (committed != NULL) {
                        *committed = 1;
                }
                /*
                 * If we get an error during the commit processing,
                 * release the buffer that is still held and return
                 * to the caller.
                 */
                if (code) {
                        xfs_buf_relse(ialloc_context);
                        if (dqinfo) {
                                tp->t_dqinfo = dqinfo;
                                xfs_trans_free_dqinfo(tp);
                        }
                        *tpp = ntp;
                        *ipp = NULL;
                        return code;
                }

                /*
                 * transaction commit worked ok so we can drop the extra ticket
                 * reference that we gained in xfs_trans_dup()
                 */
                xfs_log_ticket_put(tp->t_ticket);
                tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
                code = xfs_trans_reserve(tp, &tres, 0, 0);

                /*
                 * Re-attach the quota info that we detached from prev trx.
                 */
                if (dqinfo) {
                        tp->t_dqinfo = dqinfo;
                        tp->t_flags |= tflags;
                }

                if (code) {
                        xfs_buf_relse(ialloc_context);
                        *tpp = ntp;
                        *ipp = NULL;
                        return code;
                }
                xfs_trans_bjoin(tp, ialloc_context);

                /*
                 * Call ialloc again. Since we've locked out all
                 * other allocations in this allocation group,
                 * this call should always succeed.
                 */
                code = xfs_ialloc(tp, dp, mode, nlink, rdev, prid,
                                  okalloc, &ialloc_context, &ip);

                /*
                 * If we get an error at this point, return to the caller
                 * so that the current transaction can be aborted.
                 */
                if (code) {
                        *tpp = tp;
                        *ipp = NULL;
                        return code;
                }
                ASSERT(!ialloc_context && ip);

        } else {
                if (committed != NULL)
                        *committed = 0;
        }

        *ipp = ip;
        *tpp = tp;

        return 0;
}

/*
 * Decrement the link count on an inode & log the change.
 * If this causes the link count to go to zero, initiate the
 * logging activity required to truncate a file.
 */
int                             /* error */
xfs_droplink(
        xfs_trans_t *tp,
        xfs_inode_t *ip)
{
        int     error;

        xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);

        ASSERT (ip->i_d.di_nlink > 0);
        ip->i_d.di_nlink--;
        drop_nlink(VFS_I(ip));
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        error = 0;
        if (ip->i_d.di_nlink == 0) {
                /*
                 * We're dropping the last link to this file.
                 * Move the on-disk inode to the AGI unlinked list.
                 * From xfs_inactive() we will pull the inode from
                 * the list and free it.
                 */
                error = xfs_iunlink(tp, ip);
        }
        return error;
}

/*
 * Increment the link count on an inode & log the change.
 */
int
xfs_bumplink(
        xfs_trans_t *tp,
        xfs_inode_t *ip)
{
        xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);

        ASSERT(ip->i_d.di_version > 1);
        ASSERT(ip->i_d.di_nlink > 0 || (VFS_I(ip)->i_state & I_LINKABLE));
        ip->i_d.di_nlink++;
        inc_nlink(VFS_I(ip));
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        return 0;
}

int
xfs_create(
        xfs_inode_t             *dp,
        struct xfs_name         *name,
        umode_t                 mode,
        xfs_dev_t               rdev,
        xfs_inode_t             **ipp)
{
        int                     is_dir = S_ISDIR(mode);
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_inode        *ip = NULL;
        struct xfs_trans        *tp = NULL;
        int                     error;
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        bool                    unlock_dp_on_error = false;
        uint                    cancel_flags;
        int                     committed;
        prid_t                  prid;
        struct xfs_dquot        *udqp = NULL;
        struct xfs_dquot        *gdqp = NULL;
        struct xfs_dquot        *pdqp = NULL;
        struct xfs_trans_res    *tres;
        uint                    resblks;

        trace_xfs_create(dp, name);

        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;

        prid = xfs_get_initial_prid(dp);

        /*
         * Make sure that we have allocated dquot(s) on disk.
         */
        error = xfs_qm_vop_dqalloc(dp, xfs_kuid_to_uid(current_fsuid()),
                                        xfs_kgid_to_gid(current_fsgid()), prid,
                                        XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
                                        &udqp, &gdqp, &pdqp);
        if (error)
                return error;

        if (is_dir) {
                rdev = 0;
                resblks = XFS_MKDIR_SPACE_RES(mp, name->len);
                tres = &M_RES(mp)->tr_mkdir;
                tp = xfs_trans_alloc(mp, XFS_TRANS_MKDIR);
        } else {
                resblks = XFS_CREATE_SPACE_RES(mp, name->len);
                tres = &M_RES(mp)->tr_create;
                tp = xfs_trans_alloc(mp, XFS_TRANS_CREATE);
        }

        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;

        /*
         * Initially assume that the file does not exist and
         * reserve the resources for that case.  If that is not
         * the case we'll drop the one we have and get a more
         * appropriate transaction later.
         */
        error = xfs_trans_reserve(tp, tres, resblks, 0);
        if (error == -ENOSPC) {
                /* flush outstanding delalloc blocks and retry */
                xfs_flush_inodes(mp);
                error = xfs_trans_reserve(tp, tres, resblks, 0);
        }
        if (error == -ENOSPC) {
                /* No space at all so try a "no-allocation" reservation */
                resblks = 0;
                error = xfs_trans_reserve(tp, tres, 0, 0);
        }
        if (error) {
                cancel_flags = 0;
                goto out_trans_cancel;
        }

        xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
        unlock_dp_on_error = true;

        xfs_bmap_init(&free_list, &first_block);

        /*
         * Reserve disk quota and the inode.
         */
        error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
                                                pdqp, resblks, 1, 0);
        if (error)
                goto out_trans_cancel;

        if (!resblks) {
                error = xfs_dir_canenter(tp, dp, name);
                if (error)
                        goto out_trans_cancel;
        }

        /*
         * A newly created regular or special file just has one directory
         * entry pointing to them, but a directory also the "." entry
         * pointing to itself.
         */
        error = xfs_dir_ialloc(&tp, dp, mode, is_dir ? 2 : 1, rdev,
                               prid, resblks > 0, &ip, &committed);
        if (error) {
                if (error == -ENOSPC)
                        goto out_trans_cancel;
                goto out_trans_abort;
        }

        /*
         * Now we join the directory inode to the transaction.  We do not do it
         * earlier because xfs_dir_ialloc might commit the previous transaction
         * (and release all the locks).  An error from here on will result in
         * the transaction cancel unlocking dp so don't do it explicitly in the
         * error path.
         */
        xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
        unlock_dp_on_error = false;

        error = xfs_dir_createname(tp, dp, name, ip->i_ino,
                                        &first_block, &free_list, resblks ?
                                        resblks - XFS_IALLOC_SPACE_RES(mp) : 0);
        if (error) {
                ASSERT(error != -ENOSPC);
                goto out_trans_abort;
        }
        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

        if (is_dir) {
                error = xfs_dir_init(tp, ip, dp);
                if (error)
                        goto out_bmap_cancel;

                error = xfs_bumplink(tp, dp);
                if (error)
                        goto out_bmap_cancel;
        }

        /*
         * If this is a synchronous mount, make sure that the
         * create transaction goes to disk before returning to
         * the user.
         */
        if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
                xfs_trans_set_sync(tp);

        /*
         * Attach the dquot(s) to the inodes and modify them incore.
         * These ids of the inode couldn't have changed since the new
         * inode has been locked ever since it was created.
         */
        xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error)
                goto out_bmap_cancel;

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                goto out_release_inode;

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);
        xfs_qm_dqrele(pdqp);

        *ipp = ip;
        return 0;

 out_bmap_cancel:
        xfs_bmap_cancel(&free_list);
 out_trans_abort:
        cancel_flags |= XFS_TRANS_ABORT;
 out_trans_cancel:
        xfs_trans_cancel(tp, cancel_flags);
 out_release_inode:
        /*
         * Wait until after the current transaction is aborted to
         * release the inode.  This prevents recursive transactions
         * and deadlocks from xfs_inactive.
         */
        if (ip)
                IRELE(ip);

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);
        xfs_qm_dqrele(pdqp);

        if (unlock_dp_on_error)
                xfs_iunlock(dp, XFS_ILOCK_EXCL);
        return error;
}

int
xfs_create_tmpfile(
        struct xfs_inode        *dp,
        struct dentry           *dentry,
        umode_t                 mode,
        struct xfs_inode        **ipp)
{
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_inode        *ip = NULL;
        struct xfs_trans        *tp = NULL;
        int                     error;
        uint                    cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
        prid_t                  prid;
        struct xfs_dquot        *udqp = NULL;
        struct xfs_dquot        *gdqp = NULL;
        struct xfs_dquot        *pdqp = NULL;
        struct xfs_trans_res    *tres;
        uint                    resblks;

        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;

        prid = xfs_get_initial_prid(dp);

        /*
         * Make sure that we have allocated dquot(s) on disk.
         */
        error = xfs_qm_vop_dqalloc(dp, xfs_kuid_to_uid(current_fsuid()),
                                xfs_kgid_to_gid(current_fsgid()), prid,
                                XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
                                &udqp, &gdqp, &pdqp);
        if (error)
                return error;

        resblks = XFS_IALLOC_SPACE_RES(mp);
        tp = xfs_trans_alloc(mp, XFS_TRANS_CREATE_TMPFILE);

        tres = &M_RES(mp)->tr_create_tmpfile;
        error = xfs_trans_reserve(tp, tres, resblks, 0);
        if (error == -ENOSPC) {
                /* No space at all so try a "no-allocation" reservation */
                resblks = 0;
                error = xfs_trans_reserve(tp, tres, 0, 0);
        }
        if (error) {
                cancel_flags = 0;
                goto out_trans_cancel;
        }

        error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
                                                pdqp, resblks, 1, 0);
        if (error)
                goto out_trans_cancel;

        error = xfs_dir_ialloc(&tp, dp, mode, 1, 0,
                                prid, resblks > 0, &ip, NULL);
        if (error) {
                if (error == -ENOSPC)
                        goto out_trans_cancel;
                goto out_trans_abort;
        }

        if (mp->m_flags & XFS_MOUNT_WSYNC)
                xfs_trans_set_sync(tp);

        /*
         * Attach the dquot(s) to the inodes and modify them incore.
         * These ids of the inode couldn't have changed since the new
         * inode has been locked ever since it was created.
         */
        xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);

        ip->i_d.di_nlink--;
        error = xfs_iunlink(tp, ip);
        if (error)
                goto out_trans_abort;

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                goto out_release_inode;

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);
        xfs_qm_dqrele(pdqp);

        *ipp = ip;
        return 0;

 out_trans_abort:
        cancel_flags |= XFS_TRANS_ABORT;
 out_trans_cancel:
        xfs_trans_cancel(tp, cancel_flags);
 out_release_inode:
        /*
         * Wait until after the current transaction is aborted to
         * release the inode.  This prevents recursive transactions
         * and deadlocks from xfs_inactive.
         */
        if (ip)
                IRELE(ip);

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);
        xfs_qm_dqrele(pdqp);

        return error;
}

int
xfs_link(
        xfs_inode_t             *tdp,
        xfs_inode_t             *sip,
        struct xfs_name         *target_name)
{
        xfs_mount_t             *mp = tdp->i_mount;
        xfs_trans_t             *tp;
        int                     error;
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        int                     cancel_flags;
        int                     committed;
        int                     resblks;

        trace_xfs_link(tdp, target_name);

        ASSERT(!S_ISDIR(sip->i_d.di_mode));

        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;

        error = xfs_qm_dqattach(sip, 0);
        if (error)
                goto std_return;

        error = xfs_qm_dqattach(tdp, 0);
        if (error)
                goto std_return;

        tp = xfs_trans_alloc(mp, XFS_TRANS_LINK);
        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
        resblks = XFS_LINK_SPACE_RES(mp, target_name->len);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_link, resblks, 0);
        if (error == -ENOSPC) {
                resblks = 0;
                error = xfs_trans_reserve(tp, &M_RES(mp)->tr_link, 0, 0);
        }
        if (error) {
                cancel_flags = 0;
                goto error_return;
        }

        xfs_lock_two_inodes(sip, tdp, XFS_ILOCK_EXCL);

        xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);

        /*
         * If we are using project inheritance, we only allow hard link
         * creation in our tree when the project IDs are the same; else
         * the tree quota mechanism could be circumvented.
         */
        if (unlikely((tdp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
                     (xfs_get_projid(tdp) != xfs_get_projid(sip)))) {
                error = -EXDEV;
                goto error_return;
        }

        if (!resblks) {
                error = xfs_dir_canenter(tp, tdp, target_name);
                if (error)
                        goto error_return;
        }

        xfs_bmap_init(&free_list, &first_block);

        if (sip->i_d.di_nlink == 0) {
                error = xfs_iunlink_remove(tp, sip);
                if (error)
                        goto abort_return;
        }

        error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
                                        &first_block, &free_list, resblks);
        if (error)
                goto abort_return;
        xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);

        error = xfs_bumplink(tp, sip);
        if (error)
                goto abort_return;

        /*
         * If this is a synchronous mount, make sure that the
         * link transaction goes to disk before returning to
         * the user.
         */
        if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
                xfs_trans_set_sync(tp);
        }

        error = xfs_bmap_finish (&tp, &free_list, &committed);
        if (error) {
                xfs_bmap_cancel(&free_list);
                goto abort_return;
        }

        return xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);

 abort_return:
        cancel_flags |= XFS_TRANS_ABORT;
 error_return:
        xfs_trans_cancel(tp, cancel_flags);
 std_return:
        return error;
}

/*
 * Free up the underlying blocks past new_size.  The new size must be smaller
 * than the current size.  This routine can be used both for the attribute and
 * data fork, and does not modify the inode size, which is left to the caller.
 *
 * The transaction passed to this routine must have made a permanent log
 * reservation of at least XFS_ITRUNCATE_LOG_RES.  This routine may commit the
 * given transaction and start new ones, so make sure everything involved in
 * the transaction is tidy before calling here.  Some transaction will be
 * returned to the caller to be committed.  The incoming transaction must
 * already include the inode, and both inode locks must be held exclusively.
 * The inode must also be "held" within the transaction.  On return the inode
 * will be "held" within the returned transaction.  This routine does NOT
 * require any disk space to be reserved for it within the transaction.
 *
 * If we get an error, we must return with the inode locked and linked into the
 * current transaction. This keeps things simple for the higher level code,
 * because it always knows that the inode is locked and held in the transaction
 * that returns to it whether errors occur or not.  We don't mark the inode
 * dirty on error so that transactions can be easily aborted if possible.
 */
int
xfs_itruncate_extents(
        struct xfs_trans        **tpp,
        struct xfs_inode        *ip,
        int                     whichfork,
        xfs_fsize_t             new_size)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_trans        *tp = *tpp;
        struct xfs_trans        *ntp;
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        xfs_fileoff_t           first_unmap_block;
        xfs_fileoff_t           last_block;
        xfs_filblks_t           unmap_len;
        int                     committed;
        int                     error = 0;
        int                     done = 0;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        ASSERT(!atomic_read(&VFS_I(ip)->i_count) ||
               xfs_isilocked(ip, XFS_IOLOCK_EXCL));
        ASSERT(new_size <= XFS_ISIZE(ip));
        ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
        ASSERT(ip->i_itemp != NULL);
        ASSERT(ip->i_itemp->ili_lock_flags == 0);
        ASSERT(!XFS_NOT_DQATTACHED(mp, ip));

        trace_xfs_itruncate_extents_start(ip, new_size);

        /*
         * Since it is possible for space to become allocated beyond
         * the end of the file (in a crash where the space is allocated
         * but the inode size is not yet updated), simply remove any
         * blocks which show up between the new EOF and the maximum
         * possible file size.  If the first block to be removed is
         * beyond the maximum file size (ie it is the same as last_block),
         * then there is nothing to do.
         */
        first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
        last_block = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
        if (first_unmap_block == last_block)
                return 0;

        ASSERT(first_unmap_block < last_block);
        unmap_len = last_block - first_unmap_block + 1;
        while (!done) {
                xfs_bmap_init(&free_list, &first_block);
                error = xfs_bunmapi(tp, ip,
                                    first_unmap_block, unmap_len,
                                    xfs_bmapi_aflag(whichfork),
                                    XFS_ITRUNC_MAX_EXTENTS,
                                    &first_block, &free_list,
                                    &done);
                if (error)
                        goto out_bmap_cancel;

                /*
                 * Duplicate the transaction that has the permanent
                 * reservation and commit the old transaction.
                 */
                error = xfs_bmap_finish(&tp, &free_list, &committed);
                if (committed)
                        xfs_trans_ijoin(tp, ip, 0);
                if (error)
                        goto out_bmap_cancel;

                if (committed) {
                        /*
                         * Mark the inode dirty so it will be logged and
                         * moved forward in the log as part of every commit.
                         */
                        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
                }

                ntp = xfs_trans_dup(tp);
                error = xfs_trans_commit(tp, 0);
                tp = ntp;

                xfs_trans_ijoin(tp, ip, 0);

                if (error)
                        goto out;

                /*
                 * Transaction commit worked ok so we can drop the extra ticket
                 * reference that we gained in xfs_trans_dup()
                 */
                xfs_log_ticket_put(tp->t_ticket);
                error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
                if (error)
                        goto out;
        }

        /*
         * Always re-log the inode so that our permanent transaction can keep
         * on rolling it forward in the log.
         */
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        trace_xfs_itruncate_extents_end(ip, new_size);

out:
        *tpp = tp;
        return error;
out_bmap_cancel:
        /*
         * If the bunmapi call encounters an error, return to the caller where
         * the transaction can be properly aborted.  We just need to make sure
         * we're not holding any resources that we were not when we came in.
         */
        xfs_bmap_cancel(&free_list);
        goto out;
}

int
xfs_release(
        xfs_inode_t     *ip)
{
        xfs_mount_t     *mp = ip->i_mount;
        int             error;

        if (!S_ISREG(ip->i_d.di_mode) || (ip->i_d.di_mode == 0))
                return 0;

        /* If this is a read-only mount, don't do this (would generate I/O) */
        if (mp->m_flags & XFS_MOUNT_RDONLY)
                return 0;

        if (!XFS_FORCED_SHUTDOWN(mp)) {
                int truncated;

                /*
                 * If we previously truncated this file and removed old data
                 * in the process, we want to initiate "early" writeout on
                 * the last close.  This is an attempt to combat the notorious
                 * NULL files problem which is particularly noticeable from a
                 * truncate down, buffered (re-)write (delalloc), followed by
                 * a crash.  What we are effectively doing here is
                 * significantly reducing the time window where we'd otherwise
                 * be exposed to that problem.
                 */
                truncated = xfs_iflags_test_and_clear(ip, XFS_ITRUNCATED);
                if (truncated) {
                        xfs_iflags_clear(ip, XFS_IDIRTY_RELEASE);
                        if (ip->i_delayed_blks > 0) {
                                error = filemap_flush(VFS_I(ip)->i_mapping);
                                if (error)
                                        return error;
                        }
                }
        }

        if (ip->i_d.di_nlink == 0)
                return 0;

        if (xfs_can_free_eofblocks(ip, false)) {

                /*
                 * If we can't get the iolock just skip truncating the blocks
                 * past EOF because we could deadlock with the mmap_sem
                 * otherwise.  We'll get another chance to drop them once the
                 * last reference to the inode is dropped, so we'll never leak
                 * blocks permanently.
                 *
                 * Further, check if the inode is being opened, written and
                 * closed frequently and we have delayed allocation blocks
                 * outstanding (e.g. streaming writes from the NFS server),
                 * truncating the blocks past EOF will cause fragmentation to
                 * occur.
                 *
                 * In this case don't do the truncation, either, but we have to
                 * be careful how we detect this case. Blocks beyond EOF show
                 * up as i_delayed_blks even when the inode is clean, so we
                 * need to truncate them away first before checking for a dirty
                 * release. Hence on the first dirty close we will still remove
                 * the speculative allocation, but after that we will leave it
                 * in place.
                 */
                if (xfs_iflags_test(ip, XFS_IDIRTY_RELEASE))
                        return 0;

                error = xfs_free_eofblocks(mp, ip, true);
                if (error && error != -EAGAIN)
                        return error;

                /* delalloc blocks after truncation means it really is dirty */
                if (ip->i_delayed_blks)
                        xfs_iflags_set(ip, XFS_IDIRTY_RELEASE);
        }
        return 0;
}

/*
 * xfs_inactive_truncate
 *
 * Called to perform a truncate when an inode becomes unlinked.
 */
STATIC int
xfs_inactive_truncate(
        struct xfs_inode *ip)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_trans        *tp;
        int                     error;

        tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
        if (error) {
                ASSERT(XFS_FORCED_SHUTDOWN(mp));
                xfs_trans_cancel(tp, 0);
                return error;
        }

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, 0);

        /*
         * Log the inode size first to prevent stale data exposure in the event
         * of a system crash before the truncate completes. See the related
         * comment in xfs_setattr_size() for details.
         */
        ip->i_d.di_size = 0;
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK, 0);
        if (error)
                goto error_trans_cancel;

        ASSERT(ip->i_d.di_nextents == 0);

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                goto error_unlock;

        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return 0;

error_trans_cancel:
        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
error_unlock:
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return error;
}

/*
 * xfs_inactive_ifree()
 *
 * Perform the inode free when an inode is unlinked.
 */
STATIC int
xfs_inactive_ifree(
        struct xfs_inode *ip)
{
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        int                     committed;
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_trans        *tp;
        int                     error;

        tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);

        /*
         * The ifree transaction might need to allocate blocks for record
         * insertion to the finobt. We don't want to fail here at ENOSPC, so
         * allow ifree to dip into the reserved block pool if necessary.
         *
         * Freeing large sets of inodes generally means freeing inode chunks,
         * directory and file data blocks, so this should be relatively safe.
         * Only under severe circumstances should it be possible to free enough
         * inodes to exhaust the reserve block pool via finobt expansion while
         * at the same time not creating free space in the filesystem.
         *
         * Send a warning if the reservation does happen to fail, as the inode
         * now remains allocated and sits on the unlinked list until the fs is
         * repaired.
         */
        tp->t_flags |= XFS_TRANS_RESERVE;
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ifree,
                                  XFS_IFREE_SPACE_RES(mp), 0);
        if (error) {
                if (error == -ENOSPC) {
                        xfs_warn_ratelimited(mp,
                        "Failed to remove inode(s) from unlinked list. "
                        "Please free space, unmount and run xfs_repair.");
                } else {
                        ASSERT(XFS_FORCED_SHUTDOWN(mp));
                }
                xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES);
                return error;
        }

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, 0);

        xfs_bmap_init(&free_list, &first_block);
        error = xfs_ifree(tp, ip, &free_list);
        if (error) {
                /*
                 * If we fail to free the inode, shut down.  The cancel
                 * might do that, we need to make sure.  Otherwise the
                 * inode might be lost for a long time or forever.
                 */
                if (!XFS_FORCED_SHUTDOWN(mp)) {
                        xfs_notice(mp, "%s: xfs_ifree returned error %d",
                                __func__, error);
                        xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
                }
                xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES|XFS_TRANS_ABORT);
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                return error;
        }

        /*
         * Credit the quota account(s). The inode is gone.
         */
        xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_ICOUNT, -1);

        /*
         * Just ignore errors at this point.  There is nothing we can
         * do except to try to keep going. Make sure it's not a silent
         * error.
         */
        error = xfs_bmap_finish(&tp,  &free_list, &committed);
        if (error)
                xfs_notice(mp, "%s: xfs_bmap_finish returned error %d",
                        __func__, error);
        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                xfs_notice(mp, "%s: xfs_trans_commit returned error %d",
                        __func__, error);

        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return 0;
}

/*
 * xfs_inactive
 *
 * This is called when the vnode reference count for the vnode
 * goes to zero.  If the file has been unlinked, then it must
 * now be truncated.  Also, we clear all of the read-ahead state
 * kept for the inode here since the file is now closed.
 */
void
xfs_inactive(
        xfs_inode_t     *ip)
{
        struct xfs_mount        *mp;
        int                     error;
        int                     truncate = 0;

        /*
         * If the inode is already free, then there can be nothing
         * to clean up here.
         */
        if (ip->i_d.di_mode == 0) {
                ASSERT(ip->i_df.if_real_bytes == 0);
                ASSERT(ip->i_df.if_broot_bytes == 0);
                return;
        }

        mp = ip->i_mount;

        /* If this is a read-only mount, don't do this (would generate I/O) */
        if (mp->m_flags & XFS_MOUNT_RDONLY)
                return;

        if (ip->i_d.di_nlink != 0) {
                /*
                 * force is true because we are evicting an inode from the
                 * cache. Post-eof blocks must be freed, lest we end up with
                 * broken free space accounting.
                 */
                if (xfs_can_free_eofblocks(ip, true))
                        xfs_free_eofblocks(mp, ip, false);

                return;
        }

        if (S_ISREG(ip->i_d.di_mode) &&
            (ip->i_d.di_size != 0 || XFS_ISIZE(ip) != 0 ||
             ip->i_d.di_nextents > 0 || ip->i_delayed_blks > 0))
                truncate = 1;

        error = xfs_qm_dqattach(ip, 0);
        if (error)
                return;

        if (S_ISLNK(ip->i_d.di_mode))
                error = xfs_inactive_symlink(ip);
        else if (truncate)
                error = xfs_inactive_truncate(ip);
        if (error)
                return;

        /*
         * If there are attributes associated with the file then blow them away
         * now.  The code calls a routine that recursively deconstructs the
         * attribute fork.  We need to just commit the current transaction
         * because we can't use it for xfs_attr_inactive().
         */
        if (ip->i_d.di_anextents > 0) {
                ASSERT(ip->i_d.di_forkoff != 0);

                error = xfs_attr_inactive(ip);
                if (error)
                        return;
        }

        if (ip->i_afp)
                xfs_idestroy_fork(ip, XFS_ATTR_FORK);

        ASSERT(ip->i_d.di_anextents == 0);

        /*
         * Free the inode.
         */
        error = xfs_inactive_ifree(ip);
        if (error)
                return;

        /*
         * Release the dquots held by inode, if any.
         */
        xfs_qm_dqdetach(ip);
}

/*
 * This is called when the inode's link count goes to 0.
 * We place the on-disk inode on a list in the AGI.  It
 * will be pulled from this list when the inode is freed.
 */
int
xfs_iunlink(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip)
{
        xfs_mount_t     *mp;
        xfs_agi_t       *agi;
        xfs_dinode_t    *dip;
        xfs_buf_t       *agibp;
        xfs_buf_t       *ibp;
        xfs_agino_t     agino;
        short           bucket_index;
        int             offset;
        int             error;

        ASSERT(ip->i_d.di_nlink == 0);
        ASSERT(ip->i_d.di_mode != 0);

        mp = tp->t_mountp;

        /*
         * Get the agi buffer first.  It ensures lock ordering
         * on the list.
         */
        error = xfs_read_agi(mp, tp, XFS_INO_TO_AGNO(mp, ip->i_ino), &agibp);
        if (error)
                return error;
        agi = XFS_BUF_TO_AGI(agibp);

        /*
         * Get the index into the agi hash table for the
         * list this inode will go on.
         */
        agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
        ASSERT(agino != 0);
        bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
        ASSERT(agi->agi_unlinked[bucket_index]);
        ASSERT(be32_to_cpu(agi->agi_unlinked[bucket_index]) != agino);

        if (agi->agi_unlinked[bucket_index] != cpu_to_be32(NULLAGINO)) {
                /*
                 * There is already another inode in the bucket we need
                 * to add ourselves to.  Add us at the front of the list.
                 * Here we put the head pointer into our next pointer,
                 * and then we fall through to point the head at us.
                 */
                error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
                                       0, 0);
                if (error)
                        return error;

                ASSERT(dip->di_next_unlinked == cpu_to_be32(NULLAGINO));
                dip->di_next_unlinked = agi->agi_unlinked[bucket_index];
                offset = ip->i_imap.im_boffset +
                        offsetof(xfs_dinode_t, di_next_unlinked);

                /* need to recalc the inode CRC if appropriate */
                xfs_dinode_calc_crc(mp, dip);

                xfs_trans_inode_buf(tp, ibp);
                xfs_trans_log_buf(tp, ibp, offset,
                                  (offset + sizeof(xfs_agino_t) - 1));
                xfs_inobp_check(mp, ibp);
        }

        /*
         * Point the bucket head pointer at the inode being inserted.
         */
        ASSERT(agino != 0);
        agi->agi_unlinked[bucket_index] = cpu_to_be32(agino);
        offset = offsetof(xfs_agi_t, agi_unlinked) +
                (sizeof(xfs_agino_t) * bucket_index);
        xfs_trans_buf_set_type(tp, agibp, XFS_BLFT_AGI_BUF);
        xfs_trans_log_buf(tp, agibp, offset,
                          (offset + sizeof(xfs_agino_t) - 1));
        return 0;
}

/*
 * Pull the on-disk inode from the AGI unlinked list.
 */
STATIC int
xfs_iunlink_remove(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip)
{
        xfs_ino_t       next_ino;
        xfs_mount_t     *mp;
        xfs_agi_t       *agi;
        xfs_dinode_t    *dip;
        xfs_buf_t       *agibp;
        xfs_buf_t       *ibp;
        xfs_agnumber_t  agno;
        xfs_agino_t     agino;
        xfs_agino_t     next_agino;
        xfs_buf_t       *last_ibp;
        xfs_dinode_t    *last_dip = NULL;
        short           bucket_index;
        int             offset, last_offset = 0;
        int             error;

        mp = tp->t_mountp;
        agno = XFS_INO_TO_AGNO(mp, ip->i_ino);

        /*
         * Get the agi buffer first.  It ensures lock ordering
         * on the list.
         */
        error = xfs_read_agi(mp, tp, agno, &agibp);
        if (error)
                return error;

        agi = XFS_BUF_TO_AGI(agibp);

        /*
         * Get the index into the agi hash table for the
         * list this inode will go on.
         */
        agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
        ASSERT(agino != 0);
        bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
        ASSERT(agi->agi_unlinked[bucket_index] != cpu_to_be32(NULLAGINO));
        ASSERT(agi->agi_unlinked[bucket_index]);

        if (be32_to_cpu(agi->agi_unlinked[bucket_index]) == agino) {
                /*
                 * We're at the head of the list.  Get the inode's on-disk
                 * buffer to see if there is anyone after us on the list.
                 * Only modify our next pointer if it is not already NULLAGINO.
                 * This saves us the overhead of dealing with the buffer when
                 * there is no need to change it.
                 */
                error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
                                       0, 0);
                if (error) {
                        xfs_warn(mp, "%s: xfs_imap_to_bp returned error %d.",
                                __func__, error);
                        return error;
                }
                next_agino = be32_to_cpu(dip->di_next_unlinked);
                ASSERT(next_agino != 0);
                if (next_agino != NULLAGINO) {
                        dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
                        offset = ip->i_imap.im_boffset +
                                offsetof(xfs_dinode_t, di_next_unlinked);

                        /* need to recalc the inode CRC if appropriate */
                        xfs_dinode_calc_crc(mp, dip);

                        xfs_trans_inode_buf(tp, ibp);
                        xfs_trans_log_buf(tp, ibp, offset,
                                          (offset + sizeof(xfs_agino_t) - 1));
                        xfs_inobp_check(mp, ibp);
                } else {
                        xfs_trans_brelse(tp, ibp);
                }
                /*
                 * Point the bucket head pointer at the next inode.
                 */
                ASSERT(next_agino != 0);
                ASSERT(next_agino != agino);
                agi->agi_unlinked[bucket_index] = cpu_to_be32(next_agino);
                offset = offsetof(xfs_agi_t, agi_unlinked) +
                        (sizeof(xfs_agino_t) * bucket_index);
                xfs_trans_buf_set_type(tp, agibp, XFS_BLFT_AGI_BUF);
                xfs_trans_log_buf(tp, agibp, offset,
                                  (offset + sizeof(xfs_agino_t) - 1));
        } else {
                /*
                 * We need to search the list for the inode being freed.
                 */
                next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
                last_ibp = NULL;
                while (next_agino != agino) {
                        struct xfs_imap imap;

                        if (last_ibp)
                                xfs_trans_brelse(tp, last_ibp);

                        imap.im_blkno = 0;
                        next_ino = XFS_AGINO_TO_INO(mp, agno, next_agino);

                        error = xfs_imap(mp, tp, next_ino, &imap, 0);
                        if (error) {
                                xfs_warn(mp,
        "%s: xfs_imap returned error %d.",
                                         __func__, error);
                                return error;
                        }

                        error = xfs_imap_to_bp(mp, tp, &imap, &last_dip,
                                               &last_ibp, 0, 0);
                        if (error) {
                                xfs_warn(mp,
        "%s: xfs_imap_to_bp returned error %d.",
                                        __func__, error);
                                return error;
                        }

                        last_offset = imap.im_boffset;
                        next_agino = be32_to_cpu(last_dip->di_next_unlinked);
                        ASSERT(next_agino != NULLAGINO);
                        ASSERT(next_agino != 0);
                }

                /*
                 * Now last_ibp points to the buffer previous to us on the
                 * unlinked list.  Pull us from the list.
                 */
                error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
                                       0, 0);
                if (error) {
                        xfs_warn(mp, "%s: xfs_imap_to_bp(2) returned error %d.",
                                __func__, error);
                        return error;
                }
                next_agino = be32_to_cpu(dip->di_next_unlinked);
                ASSERT(next_agino != 0);
                ASSERT(next_agino != agino);
                if (next_agino != NULLAGINO) {
                        dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
                        offset = ip->i_imap.im_boffset +
                                offsetof(xfs_dinode_t, di_next_unlinked);

                        /* need to recalc the inode CRC if appropriate */
                        xfs_dinode_calc_crc(mp, dip);

                        xfs_trans_inode_buf(tp, ibp);
                        xfs_trans_log_buf(tp, ibp, offset,
                                          (offset + sizeof(xfs_agino_t) - 1));
                        xfs_inobp_check(mp, ibp);
                } else {
                        xfs_trans_brelse(tp, ibp);
                }
                /*
                 * Point the previous inode on the list to the next inode.
                 */
                last_dip->di_next_unlinked = cpu_to_be32(next_agino);
                ASSERT(next_agino != 0);
                offset = last_offset + offsetof(xfs_dinode_t, di_next_unlinked);

                /* need to recalc the inode CRC if appropriate */
                xfs_dinode_calc_crc(mp, last_dip);

                xfs_trans_inode_buf(tp, last_ibp);
                xfs_trans_log_buf(tp, last_ibp, offset,
                                  (offset + sizeof(xfs_agino_t) - 1));
                xfs_inobp_check(mp, last_ibp);
        }
        return 0;
}

/*
 * A big issue when freeing the inode cluster is that we _cannot_ skip any
 * inodes that are in memory - they all must be marked stale and attached to
 * the cluster buffer.
 */
STATIC int
xfs_ifree_cluster(
        xfs_inode_t     *free_ip,
        xfs_trans_t     *tp,
        xfs_ino_t       inum)
{
        xfs_mount_t             *mp = free_ip->i_mount;
        int                     blks_per_cluster;
        int                     inodes_per_cluster;
        int                     nbufs;
        int                     i, j;
        xfs_daddr_t             blkno;
        xfs_buf_t               *bp;
        xfs_inode_t             *ip;
        xfs_inode_log_item_t    *iip;
        xfs_log_item_t          *lip;
        struct xfs_perag        *pag;

        pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, inum));
        blks_per_cluster = xfs_icluster_size_fsb(mp);
        inodes_per_cluster = blks_per_cluster << mp->m_sb.sb_inopblog;
        nbufs = mp->m_ialloc_blks / blks_per_cluster;

        for (j = 0; j < nbufs; j++, inum += inodes_per_cluster) {
                blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
                                         XFS_INO_TO_AGBNO(mp, inum));

                /*
                 * We obtain and lock the backing buffer first in the process
                 * here, as we have to ensure that any dirty inode that we
                 * can't get the flush lock on is attached to the buffer.
                 * If we scan the in-memory inodes first, then buffer IO can
                 * complete before we get a lock on it, and hence we may fail
                 * to mark all the active inodes on the buffer stale.
                 */
                bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, blkno,
                                        mp->m_bsize * blks_per_cluster,
                                        XBF_UNMAPPED);

                if (!bp)
                        return -ENOMEM;

                /*
                 * This buffer may not have been correctly initialised as we
                 * didn't read it from disk. That's not important because we are
                 * only using to mark the buffer as stale in the log, and to
                 * attach stale cached inodes on it. That means it will never be
                 * dispatched for IO. If it is, we want to know about it, and we
                 * want it to fail. We can acheive this by adding a write
                 * verifier to the buffer.
                 */
                 bp->b_ops = &xfs_inode_buf_ops;

                /*
                 * Walk the inodes already attached to the buffer and mark them
                 * stale. These will all have the flush locks held, so an
                 * in-memory inode walk can't lock them. By marking them all
                 * stale first, we will not attempt to lock them in the loop
                 * below as the XFS_ISTALE flag will be set.
                 */
                lip = bp->b_fspriv;
                while (lip) {
                        if (lip->li_type == XFS_LI_INODE) {
                                iip = (xfs_inode_log_item_t *)lip;
                                ASSERT(iip->ili_logged == 1);
                                lip->li_cb = xfs_istale_done;
                                xfs_trans_ail_copy_lsn(mp->m_ail,
                                                        &iip->ili_flush_lsn,
                                                        &iip->ili_item.li_lsn);
                                xfs_iflags_set(iip->ili_inode, XFS_ISTALE);
                        }
                        lip = lip->li_bio_list;
                }


                /*
                 * For each inode in memory attempt to add it to the inode
                 * buffer and set it up for being staled on buffer IO
                 * completion.  This is safe as we've locked out tail pushing
                 * and flushing by locking the buffer.
                 *
                 * We have already marked every inode that was part of a
                 * transaction stale above, which means there is no point in
                 * even trying to lock them.
                 */
                for (i = 0; i < inodes_per_cluster; i++) {
retry:
                        rcu_read_lock();
                        ip = radix_tree_lookup(&pag->pag_ici_root,
                                        XFS_INO_TO_AGINO(mp, (inum + i)));

                        /* Inode not in memory, nothing to do */
                        if (!ip) {
                                rcu_read_unlock();
                                continue;
                        }

                        /*
                         * because this is an RCU protected lookup, we could
                         * find a recently freed or even reallocated inode
                         * during the lookup. We need to check under the
                         * i_flags_lock for a valid inode here. Skip it if it
                         * is not valid, the wrong inode or stale.
                         */
                        spin_lock(&ip->i_flags_lock);
                        if (ip->i_ino != inum + i ||
                            __xfs_iflags_test(ip, XFS_ISTALE)) {
                                spin_unlock(&ip->i_flags_lock);
                                rcu_read_unlock();
                                continue;
                        }
                        spin_unlock(&ip->i_flags_lock);

                        /*
                         * Don't try to lock/unlock the current inode, but we
                         * _cannot_ skip the other inodes that we did not find
                         * in the list attached to the buffer and are not
                         * already marked stale. If we can't lock it, back off
                         * and retry.
                         */
                        if (ip != free_ip &&
                            !xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
                                rcu_read_unlock();
                                delay(1);
                                goto retry;
                        }
                        rcu_read_unlock();

                        xfs_iflock(ip);
                        xfs_iflags_set(ip, XFS_ISTALE);

                        /*
                         * we don't need to attach clean inodes or those only
                         * with unlogged changes (which we throw away, anyway).
                         */
                        iip = ip->i_itemp;
                        if (!iip || xfs_inode_clean(ip)) {
                                ASSERT(ip != free_ip);
                                xfs_ifunlock(ip);
                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                                continue;
                        }

                        iip->ili_last_fields = iip->ili_fields;
                        iip->ili_fields = 0;
                        iip->ili_logged = 1;
                        xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
                                                &iip->ili_item.li_lsn);

                        xfs_buf_attach_iodone(bp, xfs_istale_done,
                                                  &iip->ili_item);

                        if (ip != free_ip)
                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                }

                xfs_trans_stale_inode_buf(tp, bp);
                xfs_trans_binval(tp, bp);
        }

        xfs_perag_put(pag);
        return 0;
}

/*
 * This is called to return an inode to the inode free list.
 * The inode should already be truncated to 0 length and have
 * no pages associated with it.  This routine also assumes that
 * the inode is already a part of the transaction.
 *
 * The on-disk copy of the inode will have been added to the list
 * of unlinked inodes in the AGI. We need to remove the inode from
 * that list atomically with respect to freeing it here.
 */
int
xfs_ifree(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip,
        xfs_bmap_free_t *flist)
{
        int                     error;
        int                     delete;
        xfs_ino_t               first_ino;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        ASSERT(ip->i_d.di_nlink == 0);
        ASSERT(ip->i_d.di_nextents == 0);
        ASSERT(ip->i_d.di_anextents == 0);
        ASSERT(ip->i_d.di_size == 0 || !S_ISREG(ip->i_d.di_mode));
        ASSERT(ip->i_d.di_nblocks == 0);

        /*
         * Pull the on-disk inode from the AGI unlinked list.
         */
        error = xfs_iunlink_remove(tp, ip);
        if (error)
                return error;

        error = xfs_difree(tp, ip->i_ino, flist, &delete, &first_ino);
        if (error)
                return error;

        ip->i_d.di_mode = 0;            /* mark incore inode as free */
        ip->i_d.di_flags = 0;
        ip->i_d.di_dmevmask = 0;
        ip->i_d.di_forkoff = 0;         /* mark the attr fork not in use */
        ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
        ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
        /*
         * Bump the generation count so no one will be confused
         * by reincarnations of this inode.
         */
        ip->i_d.di_gen++;
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        if (delete)
                error = xfs_ifree_cluster(ip, tp, first_ino);

        return error;
}

/*
 * This is called to unpin an inode.  The caller must have the inode locked
 * in at least shared mode so that the buffer cannot be subsequently pinned
 * once someone is waiting for it to be unpinned.
 */
static void
xfs_iunpin(
        struct xfs_inode        *ip)
{
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));

        trace_xfs_inode_unpin_nowait(ip, _RET_IP_);

        /* Give the log a push to start the unpinning I/O */
        xfs_log_force_lsn(ip->i_mount, ip->i_itemp->ili_last_lsn, 0);

}

static void
__xfs_iunpin_wait(
        struct xfs_inode        *ip)
{
        wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IPINNED_BIT);
        DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IPINNED_BIT);

        xfs_iunpin(ip);

        do {
                prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
                if (xfs_ipincount(ip))
                        io_schedule();
        } while (xfs_ipincount(ip));
        finish_wait(wq, &wait.wait);
}

void
xfs_iunpin_wait(
        struct xfs_inode        *ip)
{
        if (xfs_ipincount(ip))
                __xfs_iunpin_wait(ip);
}

/*
 * Removing an inode from the namespace involves removing the directory entry
 * and dropping the link count on the inode. Removing the directory entry can
 * result in locking an AGF (directory blocks were freed) and removing a link
 * count can result in placing the inode on an unlinked list which results in
 * locking an AGI.
 *
 * The big problem here is that we have an ordering constraint on AGF and AGI
 * locking - inode allocation locks the AGI, then can allocate a new extent for
 * new inodes, locking the AGF after the AGI. Similarly, freeing the inode
 * removes the inode from the unlinked list, requiring that we lock the AGI
 * first, and then freeing the inode can result in an inode chunk being freed
 * and hence freeing disk space requiring that we lock an AGF.
 *
 * Hence the ordering that is imposed by other parts of the code is AGI before
 * AGF. This means we cannot remove the directory entry before we drop the inode
 * reference count and put it on the unlinked list as this results in a lock
 * order of AGF then AGI, and this can deadlock against inode allocation and
 * freeing. Therefore we must drop the link counts before we remove the
 * directory entry.
 *
 * This is still safe from a transactional point of view - it is not until we
 * get to xfs_bmap_finish() that we have the possibility of multiple
 * transactions in this operation. Hence as long as we remove the directory
 * entry and drop the link count in the first transaction of the remove
 * operation, there are no transactional constraints on the ordering here.
 */
int
xfs_remove(
        xfs_inode_t             *dp,
        struct xfs_name         *name,
        xfs_inode_t             *ip)
{
        xfs_mount_t             *mp = dp->i_mount;
        xfs_trans_t             *tp = NULL;
        int                     is_dir = S_ISDIR(ip->i_d.di_mode);
        int                     error = 0;
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        int                     cancel_flags;
        int                     committed;
        uint                    resblks;

        trace_xfs_remove(dp, name);

        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;

        error = xfs_qm_dqattach(dp, 0);
        if (error)
                goto std_return;

        error = xfs_qm_dqattach(ip, 0);
        if (error)
                goto std_return;

        if (is_dir)
                tp = xfs_trans_alloc(mp, XFS_TRANS_RMDIR);
        else
                tp = xfs_trans_alloc(mp, XFS_TRANS_REMOVE);
        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;

        /*
         * We try to get the real space reservation first,
         * allowing for directory btree deletion(s) implying
         * possible bmap insert(s).  If we can't get the space
         * reservation then we use 0 instead, and avoid the bmap
         * btree insert(s) in the directory code by, if the bmap
         * insert tries to happen, instead trimming the LAST
         * block from the directory.
         */
        resblks = XFS_REMOVE_SPACE_RES(mp);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_remove, resblks, 0);
        if (error == -ENOSPC) {
                resblks = 0;
                error = xfs_trans_reserve(tp, &M_RES(mp)->tr_remove, 0, 0);
        }
        if (error) {
                ASSERT(error != -ENOSPC);
                cancel_flags = 0;
                goto out_trans_cancel;
        }

        xfs_lock_two_inodes(dp, ip, XFS_ILOCK_EXCL);

        xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

        /*
         * If we're removing a directory perform some additional validation.
         */
        cancel_flags |= XFS_TRANS_ABORT;
        if (is_dir) {
                ASSERT(ip->i_d.di_nlink >= 2);
                if (ip->i_d.di_nlink != 2) {
                        error = -ENOTEMPTY;
                        goto out_trans_cancel;
                }
                if (!xfs_dir_isempty(ip)) {
                        error = -ENOTEMPTY;
                        goto out_trans_cancel;
                }

                /* Drop the link from ip's "..".  */
                error = xfs_droplink(tp, dp);
                if (error)
                        goto out_trans_cancel;

                /* Drop the "." link from ip to self.  */
                error = xfs_droplink(tp, ip);
                if (error)
                        goto out_trans_cancel;
        } else {
                /*
                 * When removing a non-directory we need to log the parent
                 * inode here.  For a directory this is done implicitly
                 * by the xfs_droplink call for the ".." entry.
                 */
                xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
        }
        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

        /* Drop the link from dp to ip. */
        error = xfs_droplink(tp, ip);
        if (error)
                goto out_trans_cancel;

        xfs_bmap_init(&free_list, &first_block);
        error = xfs_dir_removename(tp, dp, name, ip->i_ino,
                                        &first_block, &free_list, resblks);
        if (error) {
                ASSERT(error != -ENOENT);
                goto out_bmap_cancel;
        }

        /*
         * If this is a synchronous mount, make sure that the
         * remove transaction goes to disk before returning to
         * the user.
         */
        if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
                xfs_trans_set_sync(tp);

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error)
                goto out_bmap_cancel;

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                goto std_return;

        if (is_dir && xfs_inode_is_filestream(ip))
                xfs_filestream_deassociate(ip);

        return 0;

 out_bmap_cancel:
        xfs_bmap_cancel(&free_list);
 out_trans_cancel:
        xfs_trans_cancel(tp, cancel_flags);
 std_return:
        return error;
}

/*
 * Enter all inodes for a rename transaction into a sorted array.
 */
STATIC void
xfs_sort_for_rename(
        xfs_inode_t     *dp1,   /* in: old (source) directory inode */
        xfs_inode_t     *dp2,   /* in: new (target) directory inode */
        xfs_inode_t     *ip1,   /* in: inode of old entry */
        xfs_inode_t     *ip2,   /* in: inode of new entry, if it
                                   already exists, NULL otherwise. */
        xfs_inode_t     **i_tab,/* out: array of inode returned, sorted */
        int             *num_inodes)  /* out: number of inodes in array */
{
        xfs_inode_t             *temp;
        int                     i, j;

        /*
         * i_tab contains a list of pointers to inodes.  We initialize
         * the table here & we'll sort it.  We will then use it to
         * order the acquisition of the inode locks.
         *
         * Note that the table may contain duplicates.  e.g., dp1 == dp2.
         */
        i_tab[0] = dp1;
        i_tab[1] = dp2;
        i_tab[2] = ip1;
        if (ip2) {
                *num_inodes = 4;
                i_tab[3] = ip2;
        } else {
                *num_inodes = 3;
                i_tab[3] = NULL;
        }

        /*
         * Sort the elements via bubble sort.  (Remember, there are at
         * most 4 elements to sort, so this is adequate.)
         */
        for (i = 0; i < *num_inodes; i++) {
                for (j = 1; j < *num_inodes; j++) {
                        if (i_tab[j]->i_ino < i_tab[j-1]->i_ino) {
                                temp = i_tab[j];
                                i_tab[j] = i_tab[j-1];
                                i_tab[j-1] = temp;
                        }
                }
        }
}

/*
 * xfs_cross_rename()
 *
 * responsible for handling RENAME_EXCHANGE flag in renameat2() sytemcall
 */
STATIC int
xfs_cross_rename(
        struct xfs_trans        *tp,
        struct xfs_inode        *dp1,
        struct xfs_name         *name1,
        struct xfs_inode        *ip1,
        struct xfs_inode        *dp2,
        struct xfs_name         *name2,
        struct xfs_inode        *ip2,
        struct xfs_bmap_free    *free_list,
        xfs_fsblock_t           *first_block,
        int                     spaceres)
{
        int             error = 0;
        int             ip1_flags = 0;
        int             ip2_flags = 0;
        int             dp2_flags = 0;

        /* Swap inode number for dirent in first parent */
        error = xfs_dir_replace(tp, dp1, name1,
                                ip2->i_ino,
                                first_block, free_list, spaceres);
        if (error)
                goto out;

        /* Swap inode number for dirent in second parent */
        error = xfs_dir_replace(tp, dp2, name2,
                                ip1->i_ino,
                                first_block, free_list, spaceres);
        if (error)
                goto out;

        /*
         * If we're renaming one or more directories across different parents,
         * update the respective ".." entries (and link counts) to match the new
         * parents.
         */
        if (dp1 != dp2) {
                dp2_flags = XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;

                if (S_ISDIR(ip2->i_d.di_mode)) {
                        error = xfs_dir_replace(tp, ip2, &xfs_name_dotdot,
                                                dp1->i_ino, first_block,
                                                free_list, spaceres);
                        if (error)
                                goto out;

                        /* transfer ip2 ".." reference to dp1 */
                        if (!S_ISDIR(ip1->i_d.di_mode)) {
                                error = xfs_droplink(tp, dp2);
                                if (error)
                                        goto out;
                                error = xfs_bumplink(tp, dp1);
                                if (error)
                                        goto out;
                        }

                        /*
                         * Although ip1 isn't changed here, userspace needs
                         * to be warned about the change, so that applications
                         * relying on it (like backup ones), will properly
                         * notify the change
                         */
                        ip1_flags |= XFS_ICHGTIME_CHG;
                        ip2_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
                }

                if (S_ISDIR(ip1->i_d.di_mode)) {
                        error = xfs_dir_replace(tp, ip1, &xfs_name_dotdot,
                                                dp2->i_ino, first_block,
                                                free_list, spaceres);
                        if (error)
                                goto out;

                        /* transfer ip1 ".." reference to dp2 */
                        if (!S_ISDIR(ip2->i_d.di_mode)) {
                                error = xfs_droplink(tp, dp1);
                                if (error)
                                        goto out;
                                error = xfs_bumplink(tp, dp2);
                                if (error)
                                        goto out;
                        }

                        /*
                         * Although ip2 isn't changed here, userspace needs
                         * to be warned about the change, so that applications
                         * relying on it (like backup ones), will properly
                         * notify the change
                         */
                        ip1_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
                        ip2_flags |= XFS_ICHGTIME_CHG;
                }
        }

        if (ip1_flags) {
                xfs_trans_ichgtime(tp, ip1, ip1_flags);
                xfs_trans_log_inode(tp, ip1, XFS_ILOG_CORE);
        }
        if (ip2_flags) {
                xfs_trans_ichgtime(tp, ip2, ip2_flags);
                xfs_trans_log_inode(tp, ip2, XFS_ILOG_CORE);
        }
        if (dp2_flags) {
                xfs_trans_ichgtime(tp, dp2, dp2_flags);
                xfs_trans_log_inode(tp, dp2, XFS_ILOG_CORE);
        }
        xfs_trans_ichgtime(tp, dp1, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp1, XFS_ILOG_CORE);
out:
        return error;
}

/*
 * xfs_rename
 */
int
xfs_rename(
        xfs_inode_t     *src_dp,
        struct xfs_name *src_name,
        xfs_inode_t     *src_ip,
        xfs_inode_t     *target_dp,
        struct xfs_name *target_name,
        xfs_inode_t     *target_ip,
        unsigned int    flags)
{
        xfs_trans_t     *tp = NULL;
        xfs_mount_t     *mp = src_dp->i_mount;
        int             new_parent;             /* moving to a new dir */
        int             src_is_directory;       /* src_name is a directory */
        int             error;
        xfs_bmap_free_t free_list;
        xfs_fsblock_t   first_block;
        int             cancel_flags;
        int             committed;
        xfs_inode_t     *inodes[4];
        int             spaceres;
        int             num_inodes;

        trace_xfs_rename(src_dp, target_dp, src_name, target_name);

        new_parent = (src_dp != target_dp);
        src_is_directory = S_ISDIR(src_ip->i_d.di_mode);

        xfs_sort_for_rename(src_dp, target_dp, src_ip, target_ip,
                                inodes, &num_inodes);

        xfs_bmap_init(&free_list, &first_block);
        tp = xfs_trans_alloc(mp, XFS_TRANS_RENAME);
        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
        spaceres = XFS_RENAME_SPACE_RES(mp, target_name->len);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_rename, spaceres, 0);
        if (error == -ENOSPC) {
                spaceres = 0;
                error = xfs_trans_reserve(tp, &M_RES(mp)->tr_rename, 0, 0);
        }
        if (error) {
                xfs_trans_cancel(tp, 0);
                goto std_return;
        }

        /*
         * Attach the dquots to the inodes
         */
        error = xfs_qm_vop_rename_dqattach(inodes);
        if (error) {
                xfs_trans_cancel(tp, cancel_flags);
                goto std_return;
        }

        /*
         * Lock all the participating inodes. Depending upon whether
         * the target_name exists in the target directory, and
         * whether the target directory is the same as the source
         * directory, we can lock from 2 to 4 inodes.
         */
        xfs_lock_inodes(inodes, num_inodes, XFS_ILOCK_EXCL);

        /*
         * Join all the inodes to the transaction. From this point on,
         * we can rely on either trans_commit or trans_cancel to unlock
         * them.
         */
        xfs_trans_ijoin(tp, src_dp, XFS_ILOCK_EXCL);
        if (new_parent)
                xfs_trans_ijoin(tp, target_dp, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, src_ip, XFS_ILOCK_EXCL);
        if (target_ip)
                xfs_trans_ijoin(tp, target_ip, XFS_ILOCK_EXCL);

        /*
         * If we are using project inheritance, we only allow renames
         * into our tree when the project IDs are the same; else the
         * tree quota mechanism would be circumvented.
         */
        if (unlikely((target_dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
                     (xfs_get_projid(target_dp) != xfs_get_projid(src_ip)))) {
                error = -EXDEV;
                goto error_return;
        }

        /*
         * Handle RENAME_EXCHANGE flags
         */
        if (flags & RENAME_EXCHANGE) {
                if (target_ip == NULL) {
                        error = -EINVAL;
                        goto error_return;
                }
                error = xfs_cross_rename(tp, src_dp, src_name, src_ip,
                                         target_dp, target_name, target_ip,
                                         &free_list, &first_block, spaceres);
                if (error)
                        goto abort_return;
                goto finish_rename;
        }

        /*
         * Set up the target.
         */
        if (target_ip == NULL) {
                /*
                 * If there's no space reservation, check the entry will
                 * fit before actually inserting it.
                 */
                if (!spaceres) {
                        error = xfs_dir_canenter(tp, target_dp, target_name);
                        if (error)
                                goto error_return;
                }
                /*
                 * If target does not exist and the rename crosses
                 * directories, adjust the target directory link count
                 * to account for the ".." reference from the new entry.
                 */
                error = xfs_dir_createname(tp, target_dp, target_name,
                                                src_ip->i_ino, &first_block,
                                                &free_list, spaceres);
                if (error == -ENOSPC)
                        goto error_return;
                if (error)
                        goto abort_return;

                xfs_trans_ichgtime(tp, target_dp,
                                        XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

                if (new_parent && src_is_directory) {
                        error = xfs_bumplink(tp, target_dp);
                        if (error)
                                goto abort_return;
                }
        } else { /* target_ip != NULL */
                /*
                 * If target exists and it's a directory, check that both
                 * target and source are directories and that target can be
                 * destroyed, or that neither is a directory.
                 */
                if (S_ISDIR(target_ip->i_d.di_mode)) {
                        /*
                         * Make sure target dir is empty.
                         */
                        if (!(xfs_dir_isempty(target_ip)) ||
                            (target_ip->i_d.di_nlink > 2)) {
                                error = -EEXIST;
                                goto error_return;
                        }
                }

                /*
                 * Link the source inode under the target name.
                 * If the source inode is a directory and we are moving
                 * it across directories, its ".." entry will be
                 * inconsistent until we replace that down below.
                 *
                 * In case there is already an entry with the same
                 * name at the destination directory, remove it first.
                 */
                error = xfs_dir_replace(tp, target_dp, target_name,
                                        src_ip->i_ino,
                                        &first_block, &free_list, spaceres);
                if (error)
                        goto abort_return;

                xfs_trans_ichgtime(tp, target_dp,
                                        XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

                /*
                 * Decrement the link count on the target since the target
                 * dir no longer points to it.
                 */
                error = xfs_droplink(tp, target_ip);
                if (error)
                        goto abort_return;

                if (src_is_directory) {
                        /*
                         * Drop the link from the old "." entry.
                         */
                        error = xfs_droplink(tp, target_ip);
                        if (error)
                                goto abort_return;
                }
        } /* target_ip != NULL */

        /*
         * Remove the source.
         */
        if (new_parent && src_is_directory) {
                /*
                 * Rewrite the ".." entry to point to the new
                 * directory.
                 */
                error = xfs_dir_replace(tp, src_ip, &xfs_name_dotdot,
                                        target_dp->i_ino,
                                        &first_block, &free_list, spaceres);
                ASSERT(error != -EEXIST);
                if (error)
                        goto abort_return;
        }

        /*
         * We always want to hit the ctime on the source inode.
         *
         * This isn't strictly required by the standards since the source
         * inode isn't really being changed, but old unix file systems did
         * it and some incremental backup programs won't work without it.
         */
        xfs_trans_ichgtime(tp, src_ip, XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, src_ip, XFS_ILOG_CORE);

        /*
         * Adjust the link count on src_dp.  This is necessary when
         * renaming a directory, either within one parent when
         * the target existed, or across two parent directories.
         */
        if (src_is_directory && (new_parent || target_ip != NULL)) {

                /*
                 * Decrement link count on src_directory since the
                 * entry that's moved no longer points to it.
                 */
                error = xfs_droplink(tp, src_dp);
                if (error)
                        goto abort_return;
        }

        error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
                                        &first_block, &free_list, spaceres);
        if (error)
                goto abort_return;

        xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);
        if (new_parent)
                xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);

finish_rename:
        /*
         * If this is a synchronous mount, make sure that the
         * rename transaction goes to disk before returning to
         * the user.
         */
        if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
                xfs_trans_set_sync(tp);
        }

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error) {
                xfs_bmap_cancel(&free_list);
                xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES |
                                 XFS_TRANS_ABORT));
                goto std_return;
        }

        /*
         * trans_commit will unlock src_ip, target_ip & decrement
         * the vnode references.
         */
        return xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);

 abort_return:
        cancel_flags |= XFS_TRANS_ABORT;
 error_return:
        xfs_bmap_cancel(&free_list);
        xfs_trans_cancel(tp, cancel_flags);
 std_return:
        return error;
}

STATIC int
xfs_iflush_cluster(
        xfs_inode_t     *ip,
        xfs_buf_t       *bp)
{
        xfs_mount_t             *mp = ip->i_mount;
        struct xfs_perag        *pag;
        unsigned long           first_index, mask;
        unsigned long           inodes_per_cluster;
        int                     ilist_size;
        xfs_inode_t             **ilist;
        xfs_inode_t             *iq;
        int                     nr_found;
        int                     clcount = 0;
        int                     bufwasdelwri;
        int                     i;

        pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));

        inodes_per_cluster = mp->m_inode_cluster_size >> mp->m_sb.sb_inodelog;
        ilist_size = inodes_per_cluster * sizeof(xfs_inode_t *);
        ilist = kmem_alloc(ilist_size, KM_MAYFAIL|KM_NOFS);
        if (!ilist)
                goto out_put;

        mask = ~(((mp->m_inode_cluster_size >> mp->m_sb.sb_inodelog)) - 1);
        first_index = XFS_INO_TO_AGINO(mp, ip->i_ino) & mask;
        rcu_read_lock();
        /* really need a gang lookup range call here */
        nr_found = radix_tree_gang_lookup(&pag->pag_ici_root, (void**)ilist,
                                        first_index, inodes_per_cluster);
        if (nr_found == 0)
                goto out_free;

        for (i = 0; i < nr_found; i++) {
                iq = ilist[i];
                if (iq == ip)
                        continue;

                /*
                 * because this is an RCU protected lookup, we could find a
                 * recently freed or even reallocated inode during the lookup.
                 * We need to check under the i_flags_lock for a valid inode
                 * here. Skip it if it is not valid or the wrong inode.
                 */
                spin_lock(&ip->i_flags_lock);
                if (!ip->i_ino ||
                    (XFS_INO_TO_AGINO(mp, iq->i_ino) & mask) != first_index) {
                        spin_unlock(&ip->i_flags_lock);
                        continue;
                }
                spin_unlock(&ip->i_flags_lock);

                /*
                 * Do an un-protected check to see if the inode is dirty and
                 * is a candidate for flushing.  These checks will be repeated
                 * later after the appropriate locks are acquired.
                 */
                if (xfs_inode_clean(iq) && xfs_ipincount(iq) == 0)
                        continue;

                /*
                 * Try to get locks.  If any are unavailable or it is pinned,
                 * then this inode cannot be flushed and is skipped.
                 */

                if (!xfs_ilock_nowait(iq, XFS_ILOCK_SHARED))
                        continue;
                if (!xfs_iflock_nowait(iq)) {
                        xfs_iunlock(iq, XFS_ILOCK_SHARED);
                        continue;
                }
                if (xfs_ipincount(iq)) {
                        xfs_ifunlock(iq);
                        xfs_iunlock(iq, XFS_ILOCK_SHARED);
                        continue;
                }

                /*
                 * arriving here means that this inode can be flushed.  First
                 * re-check that it's dirty before flushing.
                 */
                if (!xfs_inode_clean(iq)) {
                        int     error;
                        error = xfs_iflush_int(iq, bp);
                        if (error) {
                                xfs_iunlock(iq, XFS_ILOCK_SHARED);
                                goto cluster_corrupt_out;
                        }
                        clcount++;
                } else {
                        xfs_ifunlock(iq);
                }
                xfs_iunlock(iq, XFS_ILOCK_SHARED);
        }

        if (clcount) {
                XFS_STATS_INC(xs_icluster_flushcnt);
                XFS_STATS_ADD(xs_icluster_flushinode, clcount);
        }

out_free:
        rcu_read_unlock();
        kmem_free(ilist);
out_put:
        xfs_perag_put(pag);
        return 0;


cluster_corrupt_out:
        /*
         * Corruption detected in the clustering loop.  Invalidate the
         * inode buffer and shut down the filesystem.
         */
        rcu_read_unlock();
        /*
         * Clean up the buffer.  If it was delwri, just release it --
         * brelse can handle it with no problems.  If not, shut down the
         * filesystem before releasing the buffer.
         */
        bufwasdelwri = (bp->b_flags & _XBF_DELWRI_Q);
        if (bufwasdelwri)
                xfs_buf_relse(bp);

        xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);

        if (!bufwasdelwri) {
                /*
                 * Just like incore_relse: if we have b_iodone functions,
                 * mark the buffer as an error and call them.  Otherwise
                 * mark it as stale and brelse.
                 */
                if (bp->b_iodone) {
                        XFS_BUF_UNDONE(bp);
                        xfs_buf_stale(bp);
                        xfs_buf_ioerror(bp, -EIO);
                        xfs_buf_ioend(bp);
                } else {
                        xfs_buf_stale(bp);
                        xfs_buf_relse(bp);
                }
        }

        /*
         * Unlocks the flush lock
         */
        xfs_iflush_abort(iq, false);
        kmem_free(ilist);
        xfs_perag_put(pag);
        return -EFSCORRUPTED;
}

/*
 * Flush dirty inode metadata into the backing buffer.
 *
 * The caller must have the inode lock and the inode flush lock held.  The
 * inode lock will still be held upon return to the caller, and the inode
 * flush lock will be released after the inode has reached the disk.
 *
 * The caller must write out the buffer returned in *bpp and release it.
 */
int
xfs_iflush(
        struct xfs_inode        *ip,
        struct xfs_buf          **bpp)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_buf          *bp;
        struct xfs_dinode       *dip;
        int                     error;

        XFS_STATS_INC(xs_iflush_count);

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
        ASSERT(xfs_isiflocked(ip));
        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
               ip->i_d.di_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));

        *bpp = NULL;

        xfs_iunpin_wait(ip);

        /*
         * For stale inodes we cannot rely on the backing buffer remaining
         * stale in cache for the remaining life of the stale inode and so
         * xfs_imap_to_bp() below may give us a buffer that no longer contains
         * inodes below. We have to check this after ensuring the inode is
         * unpinned so that it is safe to reclaim the stale inode after the
         * flush call.
         */
        if (xfs_iflags_test(ip, XFS_ISTALE)) {
                xfs_ifunlock(ip);
                return 0;
        }

        /*
         * This may have been unpinned because the filesystem is shutting
         * down forcibly. If that's the case we must not write this inode
         * to disk, because the log record didn't make it to disk.
         *
         * We also have to remove the log item from the AIL in this case,
         * as we wait for an empty AIL as part of the unmount process.
         */
        if (XFS_FORCED_SHUTDOWN(mp)) {
                error = -EIO;
                goto abort_out;
        }

        /*
         * Get the buffer containing the on-disk inode.
         */
        error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK,
                               0);
        if (error || !bp) {
                xfs_ifunlock(ip);
                return error;
        }

        /*
         * First flush out the inode that xfs_iflush was called with.
         */
        error = xfs_iflush_int(ip, bp);
        if (error)
                goto corrupt_out;

        /*
         * If the buffer is pinned then push on the log now so we won't
         * get stuck waiting in the write for too long.
         */
        if (xfs_buf_ispinned(bp))
                xfs_log_force(mp, 0);

        /*
         * inode clustering:
         * see if other inodes can be gathered into this write
         */
        error = xfs_iflush_cluster(ip, bp);
        if (error)
                goto cluster_corrupt_out;

        *bpp = bp;
        return 0;

corrupt_out:
        xfs_buf_relse(bp);
        xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
cluster_corrupt_out:
        error = -EFSCORRUPTED;
abort_out:
        /*
         * Unlocks the flush lock
         */
        xfs_iflush_abort(ip, false);
        return error;
}

STATIC int
xfs_iflush_int(
        struct xfs_inode        *ip,
        struct xfs_buf          *bp)
{
        struct xfs_inode_log_item *iip = ip->i_itemp;
        struct xfs_dinode       *dip;
        struct xfs_mount        *mp = ip->i_mount;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
        ASSERT(xfs_isiflocked(ip));
        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
               ip->i_d.di_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
        ASSERT(iip != NULL && iip->ili_fields != 0);
        ASSERT(ip->i_d.di_version > 1);

        /* set *dip = inode's place in the buffer */
        dip = (xfs_dinode_t *)xfs_buf_offset(bp, ip->i_imap.im_boffset);

        if (XFS_TEST_ERROR(dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC),
                               mp, XFS_ERRTAG_IFLUSH_1, XFS_RANDOM_IFLUSH_1)) {
                xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                        "%s: Bad inode %Lu magic number 0x%x, ptr 0x%p",
                        __func__, ip->i_ino, be16_to_cpu(dip->di_magic), dip);
                goto corrupt_out;
        }
        if (XFS_TEST_ERROR(ip->i_d.di_magic != XFS_DINODE_MAGIC,
                                mp, XFS_ERRTAG_IFLUSH_2, XFS_RANDOM_IFLUSH_2)) {
                xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                        "%s: Bad inode %Lu, ptr 0x%p, magic number 0x%x",
                        __func__, ip->i_ino, ip, ip->i_d.di_magic);
                goto corrupt_out;
        }
        if (S_ISREG(ip->i_d.di_mode)) {
                if (XFS_TEST_ERROR(
                    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
                    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE),
                    mp, XFS_ERRTAG_IFLUSH_3, XFS_RANDOM_IFLUSH_3)) {
                        xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                                "%s: Bad regular inode %Lu, ptr 0x%p",
                                __func__, ip->i_ino, ip);
                        goto corrupt_out;
                }
        } else if (S_ISDIR(ip->i_d.di_mode)) {
                if (XFS_TEST_ERROR(
                    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
                    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE) &&
                    (ip->i_d.di_format != XFS_DINODE_FMT_LOCAL),
                    mp, XFS_ERRTAG_IFLUSH_4, XFS_RANDOM_IFLUSH_4)) {
                        xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                                "%s: Bad directory inode %Lu, ptr 0x%p",
                                __func__, ip->i_ino, ip);
                        goto corrupt_out;
                }
        }
        if (XFS_TEST_ERROR(ip->i_d.di_nextents + ip->i_d.di_anextents >
                                ip->i_d.di_nblocks, mp, XFS_ERRTAG_IFLUSH_5,
                                XFS_RANDOM_IFLUSH_5)) {
                xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                        "%s: detected corrupt incore inode %Lu, "
                        "total extents = %d, nblocks = %Ld, ptr 0x%p",
                        __func__, ip->i_ino,
                        ip->i_d.di_nextents + ip->i_d.di_anextents,
                        ip->i_d.di_nblocks, ip);
                goto corrupt_out;
        }
        if (XFS_TEST_ERROR(ip->i_d.di_forkoff > mp->m_sb.sb_inodesize,
                                mp, XFS_ERRTAG_IFLUSH_6, XFS_RANDOM_IFLUSH_6)) {
                xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                        "%s: bad inode %Lu, forkoff 0x%x, ptr 0x%p",
                        __func__, ip->i_ino, ip->i_d.di_forkoff, ip);
                goto corrupt_out;
        }

        /*
         * Inode item log recovery for v2 inodes are dependent on the
         * di_flushiter count for correct sequencing. We bump the flush
         * iteration count so we can detect flushes which postdate a log record
         * during recovery. This is redundant as we now log every change and
         * hence this can't happen but we need to still do it to ensure
         * backwards compatibility with old kernels that predate logging all
         * inode changes.
         */
        if (ip->i_d.di_version < 3)
                ip->i_d.di_flushiter++;

        /*
         * Copy the dirty parts of the inode into the on-disk
         * inode.  We always copy out the core of the inode,
         * because if the inode is dirty at all the core must
         * be.
         */
        xfs_dinode_to_disk(dip, &ip->i_d);

        /* Wrap, we never let the log put out DI_MAX_FLUSH */
        if (ip->i_d.di_flushiter == DI_MAX_FLUSH)
                ip->i_d.di_flushiter = 0;

        xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
        if (XFS_IFORK_Q(ip))
                xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);
        xfs_inobp_check(mp, bp);

        /*
         * We've recorded everything logged in the inode, so we'd like to clear
         * the ili_fields bits so we don't log and flush things unnecessarily.
         * However, we can't stop logging all this information until the data
         * we've copied into the disk buffer is written to disk.  If we did we
         * might overwrite the copy of the inode in the log with all the data
         * after re-logging only part of it, and in the face of a crash we
         * wouldn't have all the data we need to recover.
         *
         * What we do is move the bits to the ili_last_fields field.  When
         * logging the inode, these bits are moved back to the ili_fields field.
         * In the xfs_iflush_done() routine we clear ili_last_fields, since we
         * know that the information those bits represent is permanently on
         * disk.  As long as the flush completes before the inode is logged
         * again, then both ili_fields and ili_last_fields will be cleared.
         *
         * We can play with the ili_fields bits here, because the inode lock
         * must be held exclusively in order to set bits there and the flush
         * lock protects the ili_last_fields bits.  Set ili_logged so the flush
         * done routine can tell whether or not to look in the AIL.  Also, store
         * the current LSN of the inode so that we can tell whether the item has
         * moved in the AIL from xfs_iflush_done().  In order to read the lsn we
         * need the AIL lock, because it is a 64 bit value that cannot be read
         * atomically.
         */
        iip->ili_last_fields = iip->ili_fields;
        iip->ili_fields = 0;
        iip->ili_logged = 1;

        xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
                                &iip->ili_item.li_lsn);

        /*
         * Attach the function xfs_iflush_done to the inode's
         * buffer.  This will remove the inode from the AIL
         * and unlock the inode's flush lock when the inode is
         * completely written to disk.
         */
        xfs_buf_attach_iodone(bp, xfs_iflush_done, &iip->ili_item);

        /* update the lsn in the on disk inode if required */
        if (ip->i_d.di_version == 3)
                dip->di_lsn = cpu_to_be64(iip->ili_item.li_lsn);

        /* generate the checksum. */
        xfs_dinode_calc_crc(mp, dip);

        ASSERT(bp->b_fspriv != NULL);
        ASSERT(bp->b_iodone != NULL);
        return 0;

corrupt_out:
        return -EFSCORRUPTED;
}