xfs: limit specualtive delalloc to maxioffset

Speculative delayed allocation beyond EOF near the maximum supported
file offset can result in creating delalloc extents beyond
mp->m_maxioffset (8EB). These can never be trimmed during
xfs_free_eof_blocks() because they are beyond mp->m_maxioffset, and
that results in assert failures in xfs_fs_destroy_inode() due to
delalloc blocks still being present. xfstests 071 exposes this
problem.

Limit speculative delalloc to mp->m_maxioffset to avoid this
problem.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 47e714a7bf92..7aa0c1de2e05 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -415,6 +415,15 @@ retry:
                         return error;
         }
 
+        /*
+         * Make sure preallocation does not create extents beyond the range we
+         * actually support in this filesystem.
+         */
+        if (last_fsb > XFS_B_TO_FSB(mp, mp->m_maxioffset))
+                last_fsb = XFS_B_TO_FSB(mp, mp->m_maxioffset);
+
+        ASSERT(last_fsb > offset_fsb);
+
         nimaps = XFS_WRITE_IMAPS;
         error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
                                 imap, &nimaps, XFS_BMAPI_ENTIRE);