xfs: Factor xfs_seek_hole_data into helper

Factor xfs_seek_hole_data into an unlocked helper which takes
an xfs inode rather than a file for internal use.

Also allow specification of "end" - the vfs lseek interface is
defined such that any offset past eof/i_size shall return -ENXIO,
but we will use this for quota code which does not maintain i_size,
and we want to be able to SEEK_DATA past i_size as well.  So the
lseek path can send in i_size, and the quota code can determine
its own ending offset.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 52883ac..70a4b5a 100644 (file)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1337,31 +1337,31 @@ out:
        return found;
 }
 
-STATIC loff_t
-xfs_seek_hole_data(
-       struct file             *file,
+/*
+ * caller must lock inode with xfs_ilock_data_map_shared,
+ * can we craft an appropriate ASSERT?
+ *
+ * end is because the VFS-level lseek interface is defined such that any
+ * offset past i_size shall return -ENXIO, but we use this for quota code
+ * which does not maintain i_size, and we want to SEEK_DATA past i_size.
+ */
+loff_t
+__xfs_seek_hole_data(
+       struct inode            *inode,
        loff_t                  start,
+       loff_t                  end,
        int                     whence)
 {
-       struct inode            *inode = file->f_mapping->host;
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_mount        *mp = ip->i_mount;
        loff_t                  uninitialized_var(offset);
-       xfs_fsize_t             isize;
        xfs_fileoff_t           fsbno;
-       xfs_filblks_t           end;
-       uint                    lock;
+       xfs_filblks_t           lastbno;
        int                     error;
 
-       if (XFS_FORCED_SHUTDOWN(mp))
-               return -EIO;
-
-       lock = xfs_ilock_data_map_shared(ip);
-
-       isize = i_size_read(inode);
-       if (start >= isize) {
+       if (start >= end) {
                error = -ENXIO;
-               goto out_unlock;
+               goto out_error;
        }
 
        /*
@@ -1369,22 +1369,22 @@ xfs_seek_hole_data(
         * by fsbno to the end block of the file.
         */
        fsbno = XFS_B_TO_FSBT(mp, start);
-       end = XFS_B_TO_FSB(mp, isize);
+       lastbno = XFS_B_TO_FSB(mp, end);
 
        for (;;) {
                struct xfs_bmbt_irec    map[2];
                int                     nmap = 2;
                unsigned int            i;
 
-               error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
+               error = xfs_bmapi_read(ip, fsbno, lastbno - fsbno, map, &nmap,
                                       XFS_BMAPI_ENTIRE);
                if (error)
-                       goto out_unlock;
+                       goto out_error;
 
                /* No extents at given offset, must be beyond EOF */
                if (nmap == 0) {
                        error = -ENXIO;
-                       goto out_unlock;
+                       goto out_error;
                }
 
                for (i = 0; i < nmap; i++) {
@@ -1426,7 +1426,7 @@ xfs_seek_hole_data(
                         * hole at the end of any file).
                         */
                        if (whence == SEEK_HOLE) {
-                               offset = isize;
+                               offset = end;
                                break;
                        }
                        /*
@@ -1434,7 +1434,7 @@ xfs_seek_hole_data(
                         */
                        ASSERT(whence == SEEK_DATA);
                        error = -ENXIO;
-                       goto out_unlock;
+                       goto out_error;
                }
 
                ASSERT(i > 1);
@@ -1445,14 +1445,14 @@ xfs_seek_hole_data(
                 */
                fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
                start = XFS_FSB_TO_B(mp, fsbno);
-               if (start >= isize) {
+               if (start >= end) {
                        if (whence == SEEK_HOLE) {
-                               offset = isize;
+                               offset = end;
                                break;
                        }
                        ASSERT(whence == SEEK_DATA);
                        error = -ENXIO;
-                       goto out_unlock;
+                       goto out_error;
                }
        }
 
@@ -1464,7 +1464,39 @@ out:
         * situation in particular.
         */
        if (whence == SEEK_HOLE)
-               offset = min_t(loff_t, offset, isize);
+               offset = min_t(loff_t, offset, end);
+
+       return offset;
+
+out_error:
+       return error;
+}
+
+STATIC loff_t
+xfs_seek_hole_data(
+       struct file             *file,
+       loff_t                  start,
+       int                     whence)
+{
+       struct inode            *inode = file->f_mapping->host;
+       struct xfs_inode        *ip = XFS_I(inode);
+       struct xfs_mount        *mp = ip->i_mount;
+       uint                    lock;
+       loff_t                  offset, end;
+       int                     error = 0;
+
+       if (XFS_FORCED_SHUTDOWN(mp))
+               return -EIO;
+
+       lock = xfs_ilock_data_map_shared(ip);
+
+       end = i_size_read(inode);
+       offset = __xfs_seek_hole_data(inode, start, end, whence);
+       if (offset < 0) {
+               error = offset;
+               goto out_unlock;
+       }
+
        offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 
 out_unlock:

diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index ca9e119..ed7e933 100644 (file)
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -437,6 +437,8 @@ int xfs_update_prealloc_flags(struct xfs_inode *ip,
 int    xfs_zero_eof(struct xfs_inode *ip, xfs_off_t offset,
                     xfs_fsize_t isize, bool *did_zeroing);
 int    xfs_iozero(struct xfs_inode *ip, loff_t pos, size_t count);
+loff_t __xfs_seek_hole_data(struct inode *inode, loff_t start,
+                            loff_t eof, int whence);
 
 
 /* from xfs_iops.c */