[XFS] xfs_bmap_compute_maxlevels should be based on di_forkoff

Fix up xfs_bmap_compute_maxlevels() to account for the case when we go
from using attr2 to using attr1. In that case attr1 will no longer
necessarily be at m_attr_offset>>3, but could be at a different value for
di_forkoff. Therefore, we return the worst case scenario using MINDBTPTRS
and MINABTPTRS, as this function is used for determining the maximum log
space.

SGI-PV: 979606
SGI-Modid: xfs-linux-melb:xfs-kern:30862a

Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 6d9b5448deb2..eb198c01c35d 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -4153,16 +4153,21 @@ xfs_bmap_compute_maxlevels(
          * number of leaf entries, is controlled by the type of di_nextents
          * (a signed 32-bit number, xfs_extnum_t), or by di_anextents
          * (a signed 16-bit number, xfs_aextnum_t).
+         *
+         * Note that we can no longer assume that if we are in ATTR1 that
+         * the fork offset of all the inodes will be (m_attroffset >> 3)
+         * because we could have mounted with ATTR2 and then mounted back
+         * with ATTR1, keeping the di_forkoff's fixed but probably at
+         * various positions. Therefore, for both ATTR1 and ATTR2
+         * we have to assume the worst case scenario of a minimum size
+         * available.
          */
         if (whichfork == XFS_DATA_FORK) {
                 maxleafents = MAXEXTNUM;
-                sz = (mp->m_flags & XFS_MOUNT_ATTR2) ?
-                        XFS_BMDR_SPACE_CALC(MINDBTPTRS) : mp->m_attroffset;
+                sz = XFS_BMDR_SPACE_CALC(MINDBTPTRS);
         } else {
                 maxleafents = MAXAEXTNUM;
-                sz = (mp->m_flags & XFS_MOUNT_ATTR2) ?
-                        XFS_BMDR_SPACE_CALC(MINABTPTRS) :
-                        mp->m_sb.sb_inodesize - mp->m_attroffset;
+                sz = XFS_BMDR_SPACE_CALC(MINABTPTRS);
         }
         maxrootrecs = (int)XFS_BTREE_BLOCK_MAXRECS(sz, xfs_bmdr, 0);
         minleafrecs = mp->m_bmap_dmnr[0];