/*
* This does basic POSIX ACL permission checking
*/
-static int acl_permission_check(struct inode *inode, int mask,
- int (*check_acl)(struct inode *inode, int mask))
+static int acl_permission_check(struct inode *inode, int mask, unsigned int flags,
+ int (*check_acl)(struct inode *inode, int mask, unsigned int flags))
{
umode_t mode = inode->i_mode;
mode >>= 6;
else {
if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
- int error = check_acl(inode, mask);
+ int error = check_acl(inode, mask, flags);
if (error != -EAGAIN)
return error;
}
}
/**
- * generic_permission - check for access rights on a Posix-like filesystem
+ * generic_permission - check for access rights on a Posix-like filesystem
* @inode: inode to check access rights for
* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
* @check_acl: optional callback to check for Posix ACLs
+ * @flags: IPERM_FLAG_ flags.
*
* Used to check for read/write/execute permissions on a file.
* We use "fsuid" for this, letting us set arbitrary permissions
* for filesystem access without changing the "normal" uids which
- * are used for other things..
+ * are used for other things.
+ *
+ * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
+ * request cannot be satisfied (eg. requires blocking or too much complexity).
+ * It would then be called again in ref-walk mode.
*/
-int generic_permission(struct inode *inode, int mask,
- int (*check_acl)(struct inode *inode, int mask))
+int generic_permission(struct inode *inode, int mask, unsigned int flags,
+ int (*check_acl)(struct inode *inode, int mask, unsigned int flags))
{
int ret;
/*
* Do the basic POSIX ACL permission checks.
*/
- ret = acl_permission_check(inode, mask, check_acl);
+ ret = acl_permission_check(inode, mask, flags, check_acl);
if (ret != -EACCES)
return ret;
}
if (inode->i_op->permission)
- retval = inode->i_op->permission(inode, mask);
+ retval = inode->i_op->permission(inode, mask, 0);
else
- retval = generic_permission(inode, mask, inode->i_op->check_acl);
+ retval = generic_permission(inode, mask, 0,
+ inode->i_op->check_acl);
if (retval)
return retval;
}
EXPORT_SYMBOL(path_get);
+/**
+ * path_get_long - get a long reference to a path
+ * @path: path to get the reference to
+ *
+ * Given a path increment the reference count to the dentry and the vfsmount.
+ */
+void path_get_long(struct path *path)
+{
+ mntget_long(path->mnt);
+ dget(path->dentry);
+}
+
/**
* path_put - put a reference to a path
* @path: path to put the reference to
}
EXPORT_SYMBOL(path_put);
+/**
+ * path_put_long - put a long reference to a path
+ * @path: path to put the reference to
+ *
+ * Given a path decrement the reference count to the dentry and the vfsmount.
+ */
+void path_put_long(struct path *path)
+{
+ dput(path->dentry);
+ mntput_long(path->mnt);
+}
+
+/**
+ * nameidata_drop_rcu - drop this nameidata out of rcu-walk
+ * @nd: nameidata pathwalk data to drop
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * Path walking has 2 modes, rcu-walk and ref-walk (see
+ * Documentation/filesystems/path-lookup.txt). __drop_rcu* functions attempt
+ * to drop out of rcu-walk mode and take normal reference counts on dentries
+ * and vfsmounts to transition to rcu-walk mode. __drop_rcu* functions take
+ * refcounts at the last known good point before rcu-walk got stuck, so
+ * ref-walk may continue from there. If this is not successful (eg. a seqcount
+ * has changed), then failure is returned and path walk restarts from the
+ * beginning in ref-walk mode.
+ *
+ * nameidata_drop_rcu attempts to drop the current nd->path and nd->root into
+ * ref-walk. Must be called from rcu-walk context.
+ */
+static int nameidata_drop_rcu(struct nameidata *nd)
+{
+ struct fs_struct *fs = current->fs;
+ struct dentry *dentry = nd->path.dentry;
+
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+ if (nd->root.mnt) {
+ spin_lock(&fs->lock);
+ if (nd->root.mnt != fs->root.mnt ||
+ nd->root.dentry != fs->root.dentry)
+ goto err_root;
+ }
+ spin_lock(&dentry->d_lock);
+ if (!__d_rcu_to_refcount(dentry, nd->seq))
+ goto err;
+ BUG_ON(nd->inode != dentry->d_inode);
+ spin_unlock(&dentry->d_lock);
+ if (nd->root.mnt) {
+ path_get(&nd->root);
+ spin_unlock(&fs->lock);
+ }
+ mntget(nd->path.mnt);
+
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ nd->flags &= ~LOOKUP_RCU;
+ return 0;
+err:
+ spin_unlock(&dentry->d_lock);
+err_root:
+ if (nd->root.mnt)
+ spin_unlock(&fs->lock);
+ return -ECHILD;
+}
+
+/* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */
+static inline int nameidata_drop_rcu_maybe(struct nameidata *nd)
+{
+ if (nd->flags & LOOKUP_RCU)
+ return nameidata_drop_rcu(nd);
+ return 0;
+}
+
+/**
+ * nameidata_dentry_drop_rcu - drop nameidata and dentry out of rcu-walk
+ * @nd: nameidata pathwalk data to drop
+ * @dentry: dentry to drop
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * nameidata_dentry_drop_rcu attempts to drop the current nd->path and nd->root,
+ * and dentry into ref-walk. @dentry must be a path found by a do_lookup call on
+ * @nd. Must be called from rcu-walk context.
+ */
+static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry)
+{
+ struct fs_struct *fs = current->fs;
+ struct dentry *parent = nd->path.dentry;
+
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+ if (nd->root.mnt) {
+ spin_lock(&fs->lock);
+ if (nd->root.mnt != fs->root.mnt ||
+ nd->root.dentry != fs->root.dentry)
+ goto err_root;
+ }
+ spin_lock(&parent->d_lock);
+ spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+ if (!__d_rcu_to_refcount(dentry, nd->seq))
+ goto err;
+ /*
+ * If the sequence check on the child dentry passed, then the child has
+ * not been removed from its parent. This means the parent dentry must
+ * be valid and able to take a reference at this point.
+ */
+ BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
+ BUG_ON(!parent->d_count);
+ parent->d_count++;
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&parent->d_lock);
+ if (nd->root.mnt) {
+ path_get(&nd->root);
+ spin_unlock(&fs->lock);
+ }
+ mntget(nd->path.mnt);
+
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ nd->flags &= ~LOOKUP_RCU;
+ return 0;
+err:
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&parent->d_lock);
+err_root:
+ if (nd->root.mnt)
+ spin_unlock(&fs->lock);
+ return -ECHILD;
+}
+
+/* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */
+static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry)
+{
+ if (nd->flags & LOOKUP_RCU)
+ return nameidata_dentry_drop_rcu(nd, dentry);
+ return 0;
+}
+
+/**
+ * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk
+ * @nd: nameidata pathwalk data to drop
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk.
+ * nd->path should be the final element of the lookup, so nd->root is discarded.
+ * Must be called from rcu-walk context.
+ */
+static int nameidata_drop_rcu_last(struct nameidata *nd)
+{
+ struct dentry *dentry = nd->path.dentry;
+
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+ nd->flags &= ~LOOKUP_RCU;
+ nd->root.mnt = NULL;
+ spin_lock(&dentry->d_lock);
+ if (!__d_rcu_to_refcount(dentry, nd->seq))
+ goto err_unlock;
+ BUG_ON(nd->inode != dentry->d_inode);
+ spin_unlock(&dentry->d_lock);
+
+ mntget(nd->path.mnt);
+
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+
+ return 0;
+
+err_unlock:
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ return -ECHILD;
+}
+
+/* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */
+static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd)
+{
+ if (likely(nd->flags & LOOKUP_RCU))
+ return nameidata_drop_rcu_last(nd);
+ return 0;
+}
+
/**
* release_open_intent - free up open intent resources
* @nd: pointer to nameidata
fput(nd->intent.open.file);
}
+static int d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+ int status;
+
+ status = dentry->d_op->d_revalidate(dentry, nd);
+ if (status == -ECHILD) {
+ if (nameidata_dentry_drop_rcu(nd, dentry))
+ return status;
+ status = dentry->d_op->d_revalidate(dentry, nd);
+ }
+
+ return status;
+}
+
static inline struct dentry *
do_revalidate(struct dentry *dentry, struct nameidata *nd)
{
- int status = dentry->d_op->d_revalidate(dentry, nd);
+ int status;
+
+ status = d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
/*
* The dentry failed validation.
* the dentry otherwise d_revalidate is asking us
* to return a fail status.
*/
- if (!status) {
+ if (status < 0) {
+ /* If we're in rcu-walk, we don't have a ref */
+ if (!(nd->flags & LOOKUP_RCU))
+ dput(dentry);
+ dentry = ERR_PTR(status);
+
+ } else {
+ /* Don't d_invalidate in rcu-walk mode */
+ if (nameidata_dentry_drop_rcu_maybe(nd, dentry))
+ return ERR_PTR(-ECHILD);
if (!d_invalidate(dentry)) {
dput(dentry);
dentry = NULL;
}
- } else {
- dput(dentry);
- dentry = ERR_PTR(status);
}
}
return dentry;
}
+static inline int need_reval_dot(struct dentry *dentry)
+{
+ if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
+ return 0;
+
+ if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
+ return 0;
+
+ return 1;
+}
+
/*
* force_reval_path - force revalidation of a dentry
*
/*
* only check on filesystems where it's possible for the dentry to
- * become stale. It's assumed that if this flag is set then the
- * d_revalidate op will also be defined.
+ * become stale.
*/
- if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))
+ if (!need_reval_dot(dentry))
return 0;
- status = dentry->d_op->d_revalidate(dentry, nd);
+ status = d_revalidate(dentry, nd);
if (status > 0)
return 0;
* short-cut DAC fails, then call ->permission() to do more
* complete permission check.
*/
-static int exec_permission(struct inode *inode)
+static inline int exec_permission(struct inode *inode, unsigned int flags)
{
int ret;
if (inode->i_op->permission) {
- ret = inode->i_op->permission(inode, MAY_EXEC);
- if (!ret)
- goto ok;
- return ret;
+ ret = inode->i_op->permission(inode, MAY_EXEC, flags);
+ } else {
+ ret = acl_permission_check(inode, MAY_EXEC, flags,
+ inode->i_op->check_acl);
}
- ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl);
- if (!ret)
+ if (likely(!ret))
goto ok;
+ if (ret == -ECHILD)
+ return ret;
if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH))
goto ok;
return ret;
ok:
- return security_inode_permission(inode, MAY_EXEC);
+ return security_inode_exec_permission(inode, flags);
}
static __always_inline void set_root(struct nameidata *nd)
static int link_path_walk(const char *, struct nameidata *);
+static __always_inline void set_root_rcu(struct nameidata *nd)
+{
+ if (!nd->root.mnt) {
+ struct fs_struct *fs = current->fs;
+ unsigned seq;
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ } while (read_seqcount_retry(&fs->seq, seq));
+ }
+}
+
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
{
+ int ret;
+
if (IS_ERR(link))
goto fail;
nd->path = nd->root;
path_get(&nd->root);
}
+ nd->inode = nd->path.dentry->d_inode;
- return link_path_walk(link, nd);
+ ret = link_path_walk(link, nd);
+ return ret;
fail:
path_put(&nd->path);
return PTR_ERR(link);
static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
{
- dput(nd->path.dentry);
- if (nd->path.mnt != path->mnt) {
- mntput(nd->path.mnt);
- nd->path.mnt = path->mnt;
+ if (!(nd->flags & LOOKUP_RCU)) {
+ dput(nd->path.dentry);
+ if (nd->path.mnt != path->mnt)
+ mntput(nd->path.mnt);
}
+ nd->path.mnt = path->mnt;
nd->path.dentry = path->dentry;
}
if (path->mnt != nd->path.mnt) {
path_to_nameidata(path, nd);
+ nd->inode = nd->path.dentry->d_inode;
dget(dentry);
}
mntget(path->mnt);
+
nd->last_type = LAST_BIND;
*p = dentry->d_inode->i_op->follow_link(dentry, nd);
error = PTR_ERR(*p);
return err;
}
+static int follow_up_rcu(struct path *path)
+{
+ struct vfsmount *parent;
+ struct dentry *mountpoint;
+
+ parent = path->mnt->mnt_parent;
+ if (parent == path->mnt)
+ return 0;
+ mountpoint = path->mnt->mnt_mountpoint;
+ path->dentry = mountpoint;
+ path->mnt = parent;
+ return 1;
+}
+
int follow_up(struct path *path)
{
struct vfsmount *parent;
return 1;
}
-/* no need for dcache_lock, as serialization is taken care in
- * namespace.c
+/*
+ * serialization is taken care of in namespace.c
*/
+static void __follow_mount_rcu(struct nameidata *nd, struct path *path,
+ struct inode **inode)
+{
+ while (d_mountpoint(path->dentry)) {
+ struct vfsmount *mounted;
+ mounted = __lookup_mnt(path->mnt, path->dentry, 1);
+ if (!mounted)
+ return;
+ path->mnt = mounted;
+ path->dentry = mounted->mnt_root;
+ nd->seq = read_seqcount_begin(&path->dentry->d_seq);
+ *inode = path->dentry->d_inode;
+ }
+}
+
static int __follow_mount(struct path *path)
{
int res = 0;
}
}
-/* no need for dcache_lock, as serialization is taken care in
- * namespace.c
- */
int follow_down(struct path *path)
{
struct vfsmount *mounted;
return 0;
}
-static __always_inline void follow_dotdot(struct nameidata *nd)
+static int follow_dotdot_rcu(struct nameidata *nd)
+{
+ struct inode *inode = nd->inode;
+
+ set_root_rcu(nd);
+
+ while(1) {
+ if (nd->path.dentry == nd->root.dentry &&
+ nd->path.mnt == nd->root.mnt) {
+ break;
+ }
+ if (nd->path.dentry != nd->path.mnt->mnt_root) {
+ struct dentry *old = nd->path.dentry;
+ struct dentry *parent = old->d_parent;
+ unsigned seq;
+
+ seq = read_seqcount_begin(&parent->d_seq);
+ if (read_seqcount_retry(&old->d_seq, nd->seq))
+ return -ECHILD;
+ inode = parent->d_inode;
+ nd->path.dentry = parent;
+ nd->seq = seq;
+ break;
+ }
+ if (!follow_up_rcu(&nd->path))
+ break;
+ nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+ inode = nd->path.dentry->d_inode;
+ }
+ __follow_mount_rcu(nd, &nd->path, &inode);
+ nd->inode = inode;
+
+ return 0;
+}
+
+static void follow_dotdot(struct nameidata *nd)
{
set_root(nd);
break;
}
follow_mount(&nd->path);
+ nd->inode = nd->path.dentry->d_inode;
}
/*
* It _is_ time-critical.
*/
static int do_lookup(struct nameidata *nd, struct qstr *name,
- struct path *path)
+ struct path *path, struct inode **inode)
{
struct vfsmount *mnt = nd->path.mnt;
- struct dentry *dentry, *parent;
+ struct dentry *dentry, *parent = nd->path.dentry;
struct inode *dir;
/*
* See if the low-level filesystem might want
* to use its own hash..
*/
- if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
- int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name);
+ if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
+ int err = parent->d_op->d_hash(parent, nd->inode, name);
if (err < 0)
return err;
}
* of a false negative due to a concurrent rename, we're going to
* do the non-racy lookup, below.
*/
- dentry = __d_lookup(nd->path.dentry, name);
- if (!dentry)
- goto need_lookup;
+ if (nd->flags & LOOKUP_RCU) {
+ unsigned seq;
+
+ *inode = nd->inode;
+ dentry = __d_lookup_rcu(parent, name, &seq, inode);
+ if (!dentry) {
+ if (nameidata_drop_rcu(nd))
+ return -ECHILD;
+ goto need_lookup;
+ }
+ /* Memory barrier in read_seqcount_begin of child is enough */
+ if (__read_seqcount_retry(&parent->d_seq, nd->seq))
+ return -ECHILD;
+
+ nd->seq = seq;
+ if (dentry->d_flags & DCACHE_OP_REVALIDATE)
+ goto need_revalidate;
+ path->mnt = mnt;
+ path->dentry = dentry;
+ __follow_mount_rcu(nd, path, inode);
+ } else {
+ dentry = __d_lookup(parent, name);
+ if (!dentry)
+ goto need_lookup;
found:
- if (dentry->d_op && dentry->d_op->d_revalidate)
- goto need_revalidate;
+ if (dentry->d_flags & DCACHE_OP_REVALIDATE)
+ goto need_revalidate;
done:
- path->mnt = mnt;
- path->dentry = dentry;
- __follow_mount(path);
+ path->mnt = mnt;
+ path->dentry = dentry;
+ __follow_mount(path);
+ *inode = path->dentry->d_inode;
+ }
return 0;
need_lookup:
- parent = nd->path.dentry;
dir = parent->d_inode;
+ BUG_ON(nd->inode != dir);
mutex_lock(&dir->i_mutex);
/*
static int link_path_walk(const char *name, struct nameidata *nd)
{
struct path next;
- struct inode *inode;
int err;
unsigned int lookup_flags = nd->flags;
if (!*name)
goto return_reval;
- inode = nd->path.dentry->d_inode;
if (nd->depth)
lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
/* At this point we know we have a real path component. */
for(;;) {
+ struct inode *inode;
unsigned long hash;
struct qstr this;
unsigned int c;
nd->flags |= LOOKUP_CONTINUE;
- err = exec_permission(inode);
+ if (nd->flags & LOOKUP_RCU) {
+ err = exec_permission(nd->inode, IPERM_FLAG_RCU);
+ if (err == -ECHILD) {
+ if (nameidata_drop_rcu(nd))
+ return -ECHILD;
+ goto exec_again;
+ }
+ } else {
+exec_again:
+ err = exec_permission(nd->inode, 0);
+ }
if (err)
break;
if (this.name[0] == '.') switch (this.len) {
default:
break;
- case 2:
+ case 2:
if (this.name[1] != '.')
break;
- follow_dotdot(nd);
- inode = nd->path.dentry->d_inode;
+ if (nd->flags & LOOKUP_RCU) {
+ if (follow_dotdot_rcu(nd))
+ return -ECHILD;
+ } else
+ follow_dotdot(nd);
/* fallthrough */
case 1:
continue;
}
/* This does the actual lookups.. */
- err = do_lookup(nd, &this, &next);
+ err = do_lookup(nd, &this, &next, &inode);
if (err)
break;
-
err = -ENOENT;
- inode = next.dentry->d_inode;
if (!inode)
goto out_dput;
if (inode->i_op->follow_link) {
+ /* We commonly drop rcu-walk here */
+ if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
+ return -ECHILD;
+ BUG_ON(inode != next.dentry->d_inode);
err = do_follow_link(&next, nd);
if (err)
goto return_err;
+ nd->inode = nd->path.dentry->d_inode;
err = -ENOENT;
- inode = nd->path.dentry->d_inode;
- if (!inode)
+ if (!nd->inode)
break;
- } else
+ } else {
path_to_nameidata(&next, nd);
+ nd->inode = inode;
+ }
err = -ENOTDIR;
- if (!inode->i_op->lookup)
+ if (!nd->inode->i_op->lookup)
break;
continue;
/* here ends the main loop */
if (this.name[0] == '.') switch (this.len) {
default:
break;
- case 2:
+ case 2:
if (this.name[1] != '.')
break;
- follow_dotdot(nd);
- inode = nd->path.dentry->d_inode;
+ if (nd->flags & LOOKUP_RCU) {
+ if (follow_dotdot_rcu(nd))
+ return -ECHILD;
+ } else
+ follow_dotdot(nd);
/* fallthrough */
case 1:
goto return_reval;
}
- err = do_lookup(nd, &this, &next);
+ err = do_lookup(nd, &this, &next, &inode);
if (err)
break;
- inode = next.dentry->d_inode;
if (follow_on_final(inode, lookup_flags)) {
+ if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
+ return -ECHILD;
+ BUG_ON(inode != next.dentry->d_inode);
err = do_follow_link(&next, nd);
if (err)
goto return_err;
- inode = nd->path.dentry->d_inode;
- } else
+ nd->inode = nd->path.dentry->d_inode;
+ } else {
path_to_nameidata(&next, nd);
+ nd->inode = inode;
+ }
err = -ENOENT;
- if (!inode)
+ if (!nd->inode)
break;
if (lookup_flags & LOOKUP_DIRECTORY) {
err = -ENOTDIR;
- if (!inode->i_op->lookup)
+ if (!nd->inode->i_op->lookup)
break;
}
goto return_base;
* We bypassed the ordinary revalidation routines.
* We may need to check the cached dentry for staleness.
*/
- if (nd->path.dentry && nd->path.dentry->d_sb &&
- (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
- err = -ESTALE;
+ if (need_reval_dot(nd->path.dentry)) {
/* Note: we do not d_invalidate() */
- if (!nd->path.dentry->d_op->d_revalidate(
- nd->path.dentry, nd))
+ err = d_revalidate(nd->path.dentry, nd);
+ if (!err)
+ err = -ESTALE;
+ if (err < 0)
break;
}
return_base:
+ if (nameidata_drop_rcu_last_maybe(nd))
+ return -ECHILD;
return 0;
out_dput:
- path_put_conditional(&next, nd);
+ if (!(nd->flags & LOOKUP_RCU))
+ path_put_conditional(&next, nd);
break;
}
- path_put(&nd->path);
+ if (!(nd->flags & LOOKUP_RCU))
+ path_put(&nd->path);
return_err:
return err;
}
+static inline int path_walk_rcu(const char *name, struct nameidata *nd)
+{
+ current->total_link_count = 0;
+
+ return link_path_walk(name, nd);
+}
+
+static inline int path_walk_simple(const char *name, struct nameidata *nd)
+{
+ current->total_link_count = 0;
+
+ return link_path_walk(name, nd);
+}
+
static int path_walk(const char *name, struct nameidata *nd)
{
struct path save = nd->path;
return result;
}
+static void path_finish_rcu(struct nameidata *nd)
+{
+ if (nd->flags & LOOKUP_RCU) {
+ /* RCU dangling. Cancel it. */
+ nd->flags &= ~LOOKUP_RCU;
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ }
+ if (nd->file)
+ fput(nd->file);
+}
+
+static int path_init_rcu(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
+{
+ int retval = 0;
+ int fput_needed;
+ struct file *file;
+
+ nd->last_type = LAST_ROOT; /* if there are only slashes... */
+ nd->flags = flags | LOOKUP_RCU;
+ nd->depth = 0;
+ nd->root.mnt = NULL;
+ nd->file = NULL;
+
+ if (*name=='/') {
+ struct fs_struct *fs = current->fs;
+ unsigned seq;
+
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ nd->path = nd->root;
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+
+ } else if (dfd == AT_FDCWD) {
+ struct fs_struct *fs = current->fs;
+ unsigned seq;
+
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->path = fs->pwd;
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+
+ } else {
+ struct dentry *dentry;
+
+ file = fget_light(dfd, &fput_needed);
+ retval = -EBADF;
+ if (!file)
+ goto out_fail;
+
+ dentry = file->f_path.dentry;
+
+ retval = -ENOTDIR;
+ if (!S_ISDIR(dentry->d_inode->i_mode))
+ goto fput_fail;
+
+ retval = file_permission(file, MAY_EXEC);
+ if (retval)
+ goto fput_fail;
+
+ nd->path = file->f_path;
+ if (fput_needed)
+ nd->file = file;
+
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+ }
+ nd->inode = nd->path.dentry->d_inode;
+ return 0;
+
+fput_fail:
+ fput_light(file, fput_needed);
+out_fail:
+ return retval;
+}
+
static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
{
int retval = 0;
fput_light(file, fput_needed);
}
+ nd->inode = nd->path.dentry->d_inode;
return 0;
fput_fail:
static int do_path_lookup(int dfd, const char *name,
unsigned int flags, struct nameidata *nd)
{
- int retval = path_init(dfd, name, flags, nd);
- if (!retval)
- retval = path_walk(name, nd);
- if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
- nd->path.dentry->d_inode))
- audit_inode(name, nd->path.dentry);
+ int retval;
+
+ /*
+ * Path walking is largely split up into 2 different synchronisation
+ * schemes, rcu-walk and ref-walk (explained in
+ * Documentation/filesystems/path-lookup.txt). These share much of the
+ * path walk code, but some things particularly setup, cleanup, and
+ * following mounts are sufficiently divergent that functions are
+ * duplicated. Typically there is a function foo(), and its RCU
+ * analogue, foo_rcu().
+ *
+ * -ECHILD is the error number of choice (just to avoid clashes) that
+ * is returned if some aspect of an rcu-walk fails. Such an error must
+ * be handled by restarting a traditional ref-walk (which will always
+ * be able to complete).
+ */
+ retval = path_init_rcu(dfd, name, flags, nd);
+ if (unlikely(retval))
+ return retval;
+ retval = path_walk_rcu(name, nd);
+ path_finish_rcu(nd);
if (nd->root.mnt) {
path_put(&nd->root);
nd->root.mnt = NULL;
}
+
+ if (unlikely(retval == -ECHILD || retval == -ESTALE)) {
+ /* slower, locked walk */
+ if (retval == -ESTALE)
+ flags |= LOOKUP_REVAL;
+ retval = path_init(dfd, name, flags, nd);
+ if (unlikely(retval))
+ return retval;
+ retval = path_walk(name, nd);
+ if (nd->root.mnt) {
+ path_put(&nd->root);
+ nd->root.mnt = NULL;
+ }
+ }
+
+ if (likely(!retval)) {
+ if (unlikely(!audit_dummy_context())) {
+ if (nd->path.dentry && nd->inode)
+ audit_inode(name, nd->path.dentry);
+ }
+ }
+
return retval;
}
path_get(&nd->path);
nd->root = nd->path;
path_get(&nd->root);
+ nd->inode = nd->path.dentry->d_inode;
retval = path_walk(name, nd);
if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
- nd->path.dentry->d_inode))
+ nd->inode))
audit_inode(name, nd->path.dentry);
path_put(&nd->root);
struct dentry *dentry;
int err;
- err = exec_permission(inode);
+ err = exec_permission(inode, 0);
if (err)
return ERR_PTR(err);
* See if the low-level filesystem might want
* to use its own hash..
*/
- if (base->d_op && base->d_op->d_hash) {
- err = base->d_op->d_hash(base, name);
+ if (base->d_flags & DCACHE_OP_HASH) {
+ err = base->d_op->d_hash(base, inode, name);
dentry = ERR_PTR(err);
if (err < 0)
goto out;
*/
dentry = d_lookup(base, name);
- if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
+ if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE))
dentry = do_revalidate(dentry, nd);
if (!dentry)
mutex_unlock(&dir->d_inode->i_mutex);
dput(nd->path.dentry);
nd->path.dentry = path->dentry;
+
if (error)
return error;
/* Don't check for write permission, don't truncate */
return ERR_PTR(error);
}
+/*
+ * Handle O_CREAT case for do_filp_open
+ */
static struct file *do_last(struct nameidata *nd, struct path *path,
int open_flag, int acc_mode,
int mode, const char *pathname)
follow_dotdot(nd);
dir = nd->path.dentry;
case LAST_DOT:
- if (nd->path.mnt->mnt_sb->s_type->fs_flags & FS_REVAL_DOT) {
- if (!dir->d_op->d_revalidate(dir, nd)) {
+ if (need_reval_dot(dir)) {
+ error = d_revalidate(nd->path.dentry, nd);
+ if (!error)
error = -ESTALE;
+ if (error < 0)
goto exit;
- }
}
/* fallthrough */
case LAST_ROOT:
- if (open_flag & O_CREAT)
- goto exit;
- /* fallthrough */
+ goto exit;
case LAST_BIND:
audit_inode(pathname, dir);
goto ok;
}
/* trailing slashes? */
- if (nd->last.name[nd->last.len]) {
- if (open_flag & O_CREAT)
- goto exit;
- nd->flags |= LOOKUP_DIRECTORY | LOOKUP_FOLLOW;
- }
-
- /* just plain open? */
- if (!(open_flag & O_CREAT)) {
- error = do_lookup(nd, &nd->last, path);
- if (error)
- goto exit;
- error = -ENOENT;
- if (!path->dentry->d_inode)
- goto exit_dput;
- if (path->dentry->d_inode->i_op->follow_link)
- return NULL;
- error = -ENOTDIR;
- if (nd->flags & LOOKUP_DIRECTORY) {
- if (!path->dentry->d_inode->i_op->lookup)
- goto exit_dput;
- }
- path_to_nameidata(path, nd);
- audit_inode(pathname, nd->path.dentry);
- goto ok;
- }
+ if (nd->last.name[nd->last.len])
+ goto exit;
- /* OK, it's O_CREAT */
mutex_lock(&dir->d_inode->i_mutex);
path->dentry = lookup_hash(nd);
return NULL;
path_to_nameidata(path, nd);
+ nd->inode = path->dentry->d_inode;
error = -EISDIR;
- if (S_ISDIR(path->dentry->d_inode->i_mode))
+ if (S_ISDIR(nd->inode->i_mode))
goto exit;
ok:
filp = finish_open(nd, open_flag, acc_mode);
struct path path;
int count = 0;
int flag = open_to_namei_flags(open_flag);
- int force_reval = 0;
+ int flags;
if (!(open_flag & O_CREAT))
mode = 0;
if (open_flag & O_APPEND)
acc_mode |= MAY_APPEND;
- /* find the parent */
-reval:
- error = path_init(dfd, pathname, LOOKUP_PARENT, &nd);
+ flags = LOOKUP_OPEN;
+ if (open_flag & O_CREAT) {
+ flags |= LOOKUP_CREATE;
+ if (open_flag & O_EXCL)
+ flags |= LOOKUP_EXCL;
+ }
+ if (open_flag & O_DIRECTORY)
+ flags |= LOOKUP_DIRECTORY;
+ if (!(open_flag & O_NOFOLLOW))
+ flags |= LOOKUP_FOLLOW;
+
+ filp = get_empty_filp();
+ if (!filp)
+ return ERR_PTR(-ENFILE);
+
+ filp->f_flags = open_flag;
+ nd.intent.open.file = filp;
+ nd.intent.open.flags = flag;
+ nd.intent.open.create_mode = mode;
+
+ if (open_flag & O_CREAT)
+ goto creat;
+
+ /* !O_CREAT, simple open */
+ error = do_path_lookup(dfd, pathname, flags, &nd);
+ if (unlikely(error))
+ goto out_filp;
+ error = -ELOOP;
+ if (!(nd.flags & LOOKUP_FOLLOW)) {
+ if (nd.inode->i_op->follow_link)
+ goto out_path;
+ }
+ error = -ENOTDIR;
+ if (nd.flags & LOOKUP_DIRECTORY) {
+ if (!nd.inode->i_op->lookup)
+ goto out_path;
+ }
+ audit_inode(pathname, nd.path.dentry);
+ filp = finish_open(&nd, open_flag, acc_mode);
+ return filp;
+
+creat:
+ /* OK, have to create the file. Find the parent. */
+ error = path_init_rcu(dfd, pathname,
+ LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd);
if (error)
- return ERR_PTR(error);
- if (force_reval)
- nd.flags |= LOOKUP_REVAL;
+ goto out_filp;
+ error = path_walk_rcu(pathname, &nd);
+ path_finish_rcu(&nd);
+ if (unlikely(error == -ECHILD || error == -ESTALE)) {
+ /* slower, locked walk */
+ if (error == -ESTALE) {
+reval:
+ flags |= LOOKUP_REVAL;
+ }
+ error = path_init(dfd, pathname,
+ LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd);
+ if (error)
+ goto out_filp;
- current->total_link_count = 0;
- error = link_path_walk(pathname, &nd);
- if (error) {
- filp = ERR_PTR(error);
- goto out;
+ error = path_walk_simple(pathname, &nd);
}
- if (unlikely(!audit_dummy_context()) && (open_flag & O_CREAT))
+ if (unlikely(error))
+ goto out_filp;
+ if (unlikely(!audit_dummy_context()))
audit_inode(pathname, nd.path.dentry);
/*
* We have the parent and last component.
*/
-
- error = -ENFILE;
- filp = get_empty_filp();
- if (filp == NULL)
- goto exit_parent;
- nd.intent.open.file = filp;
- filp->f_flags = open_flag;
- nd.intent.open.flags = flag;
- nd.intent.open.create_mode = mode;
- nd.flags &= ~LOOKUP_PARENT;
- nd.flags |= LOOKUP_OPEN;
- if (open_flag & O_CREAT) {
- nd.flags |= LOOKUP_CREATE;
- if (open_flag & O_EXCL)
- nd.flags |= LOOKUP_EXCL;
- }
- if (open_flag & O_DIRECTORY)
- nd.flags |= LOOKUP_DIRECTORY;
- if (!(open_flag & O_NOFOLLOW))
- nd.flags |= LOOKUP_FOLLOW;
+ nd.flags = flags;
filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
while (unlikely(!filp)) { /* trailing symlink */
struct path holder;
- struct inode *inode = path.dentry->d_inode;
void *cookie;
error = -ELOOP;
/* S_ISDIR part is a temporary automount kludge */
- if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(inode->i_mode))
+ if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(nd.inode->i_mode))
goto exit_dput;
if (count++ == 32)
goto exit_dput;
goto exit_dput;
error = __do_follow_link(&path, &nd, &cookie);
if (unlikely(error)) {
+ if (!IS_ERR(cookie) && nd.inode->i_op->put_link)
+ nd.inode->i_op->put_link(path.dentry, &nd, cookie);
/* nd.path had been dropped */
- if (!IS_ERR(cookie) && inode->i_op->put_link)
- inode->i_op->put_link(path.dentry, &nd, cookie);
- path_put(&path);
- release_open_intent(&nd);
- filp = ERR_PTR(error);
- goto out;
+ nd.path = path;
+ goto out_path;
}
holder = path;
nd.flags &= ~LOOKUP_PARENT;
filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
- if (inode->i_op->put_link)
- inode->i_op->put_link(holder.dentry, &nd, cookie);
+ if (nd.inode->i_op->put_link)
+ nd.inode->i_op->put_link(holder.dentry, &nd, cookie);
path_put(&holder);
}
out:
if (nd.root.mnt)
path_put(&nd.root);
- if (filp == ERR_PTR(-ESTALE) && !force_reval) {
- force_reval = 1;
+ if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL))
goto reval;
- }
return filp;
exit_dput:
path_put_conditional(&path, &nd);
+out_path:
+ path_put(&nd.path);
+out_filp:
if (!IS_ERR(nd.intent.open.file))
release_open_intent(&nd);
-exit_parent:
- path_put(&nd.path);
filp = ERR_PTR(error);
goto out;
}
{
dget(dentry);
shrink_dcache_parent(dentry);
- spin_lock(&dcache_lock);
spin_lock(&dentry->d_lock);
- if (atomic_read(&dentry->d_count) == 2)
+ if (dentry->d_count == 2)
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
- spin_unlock(&dcache_lock);
}
int vfs_rmdir(struct inode *dir, struct dentry *dentry)
projects / cascardo / linux.git / blobdiff