[XFS] Fix speculative allocation beyond eof

Speculative allocation beyond eof doesn't work properly.  It was
broken some time ago after a code cleanup that moved what is now
xfs_iomap_eof_align_last_fsb() and xfs_iomap_eof_want_preallocate()
out of xfs_iomap_write_delay() into separate functions.  The code
used to use the current file size in various checks but got changed
to be max(file_size, i_new_size).  Since i_new_size is the result
of 'offset + count' then in xfs_iomap_eof_want_preallocate() the
check for '(offset + count) <= isize' will always be true.

ie if 'offset + count' is > ip->i_size then isize will be i_new_size
and equal to 'offset + count'.

This change fixes all the places that used to use the current file
size.

Reviewed-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 7 insertions, 21 deletions

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 67f22b2b44b3..911062cf73a6 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -290,7 +290,6 @@ STATIC int
 xfs_iomap_eof_align_last_fsb(
         xfs_mount_t     *mp,
         xfs_inode_t     *ip,
-        xfs_fsize_t     isize,
         xfs_extlen_t    extsize,
         xfs_fileoff_t   *last_fsb)
 {
@@ -306,14 +305,14 @@ xfs_iomap_eof_align_last_fsb(
          * stripe width and we are allocating past the allocation eof.
          */
         else if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC) &&
-                (isize >= XFS_FSB_TO_B(mp, mp->m_swidth)))
+                (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_swidth)))
                 new_last_fsb = roundup_64(*last_fsb, mp->m_swidth);
         /*
          * Roundup the allocation request to a stripe unit (m_dalign) boundary
          * if the file size is >= stripe unit size, and we are allocating past
          * the allocation eof.
          */
-        else if (mp->m_dalign && (isize >= XFS_FSB_TO_B(mp, mp->m_dalign)))
+        else if (mp->m_dalign && (ip->i_size >= XFS_FSB_TO_B(mp, mp->m_dalign)))
                 new_last_fsb = roundup_64(*last_fsb, mp->m_dalign);
 
         /*
@@ -403,7 +402,6 @@ xfs_iomap_write_direct(
         xfs_filblks_t   count_fsb, resaligned;
         xfs_fsblock_t   firstfsb;
         xfs_extlen_t    extsz, temp;
-        xfs_fsize_t     isize;
         int             nimaps;
         int             bmapi_flag;
         int             quota_flag;
@@ -426,15 +424,10 @@ xfs_iomap_write_direct(
         rt = XFS_IS_REALTIME_INODE(ip);
         extsz = xfs_get_extsz_hint(ip);
 
-        isize = ip->i_size;
-        if (ip->i_new_size > isize)
-                isize = ip->i_new_size;
-
         offset_fsb = XFS_B_TO_FSBT(mp, offset);
         last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
-        if ((offset + count) > isize) {
-                error = xfs_iomap_eof_align_last_fsb(mp, ip, isize, extsz,
-                                                        &last_fsb);
+        if ((offset + count) > ip->i_size) {
+                error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
                 if (error)
                         goto error_out;
         } else {
@@ -559,7 +552,6 @@ STATIC int
 xfs_iomap_eof_want_preallocate(
         xfs_mount_t     *mp,
         xfs_inode_t     *ip,
-        xfs_fsize_t     isize,
         xfs_off_t       offset,
         size_t          count,
         int             ioflag,
@@ -573,7 +565,7 @@ xfs_iomap_eof_want_preallocate(
         int             n, error, imaps;
 
         *prealloc = 0;
-        if ((ioflag & BMAPI_SYNC) || (offset + count) <= isize)
+        if ((ioflag & BMAPI_SYNC) || (offset + count) <= ip->i_size)
                 return 0;
 
         /*
@@ -617,7 +609,6 @@ xfs_iomap_write_delay(
         xfs_fileoff_t   ioalign;
         xfs_fsblock_t   firstblock;
         xfs_extlen_t    extsz;
-        xfs_fsize_t     isize;
         int             nimaps;
         xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
         int             prealloc, fsynced = 0;
@@ -637,11 +628,7 @@ xfs_iomap_write_delay(
         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 
 retry:
-        isize = ip->i_size;
-        if (ip->i_new_size > isize)
-                isize = ip->i_new_size;
-
-        error = xfs_iomap_eof_want_preallocate(mp, ip, isize, offset, count,
+        error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
                                 ioflag, imap, XFS_WRITE_IMAPS, &prealloc);
         if (error)
                 return error;
@@ -655,8 +642,7 @@ retry:
         }
 
         if (prealloc || extsz) {
-                error = xfs_iomap_eof_align_last_fsb(mp, ip, isize, extsz,
-                                                        &last_fsb);
+                error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
                 if (error)
                         return error;
         }