When filling in the middle of a previous delayed allocation in
xfs_bmap_add_extent_delay_real, set br_startblock of the new delay extent to
the right to nullstartblock instead of 0 before inserting the extent into the
ifork (xfs_iext_insert), rather than setting br_startblock afterward.
Adding the extent into the ifork with br_startblock=0 can lead to the extent
being copied into the btree by xfs_bmap_extent_to_btree if we happen to convert
from extents format to btree format before updating br_startblock with the
correct value. The unexpected addition of this delay extent to the btree can
cause subsequent XFS_WANT_CORRUPTED_GOTO filesystem shutdown in several
xfs_bmap_add_extent_delay_real cases where we are converting a delay extent to
real and unexpectedly find an extent already inserted. For example:
911 case BMAP_LEFT_FILLING:
912 /*
913 * Filling in the first part of a previous delayed allocation.
914 * The left neighbor is not contiguous.
915 */
916 trace_xfs_bmap_pre_update(ip, idx, state, _THIS_IP_);
917 xfs_bmbt_set_startoff(ep, new_endoff);
918 temp = PREV.br_blockcount - new->br_blockcount;
919 xfs_bmbt_set_blockcount(ep, temp);
920 xfs_iext_insert(ip, idx, 1, new, state);
921 ip->i_df.if_lastex = idx;
922 ip->i_d.di_nextents++;
923 if (cur == NULL)
924 rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
925 else {
926 rval = XFS_ILOG_CORE;
927 if ((error = xfs_bmbt_lookup_eq(cur, new->br_startoff,
928 new->br_startblock, new->br_blockcount,
929 &i)))
930 goto done;
931 XFS_WANT_CORRUPTED_GOTO(i == 0, done);
With the bogus extent in the btree we shutdown the filesystem at 931. The
conversion from extents to btree format happens when the number of extents in
the inode increases above ip->i_df.if_ext_max. xfs_bmap_extent_to_btree copies
extents from the ifork into the btree, ignoring all delalloc extents which are
denoted by br_startblock having some value of nullstartblock.
SGI-PV: 1013221
Signed-off-by: Ben Myers <bpm@xxxxxxx>
---
fs/xfs/xfs_bmap.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 4111cd3..754259f 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -1040,13 +1040,14 @@ xfs_bmap_add_extent_delay_real(
* This case is avoided almost all the time.
*/
temp = new->br_startoff - PREV.br_startoff;
+ temp2 = PREV.br_startoff + PREV.br_blockcount - new_endoff;
trace_xfs_bmap_pre_update(ip, idx, 0, _THIS_IP_);
- xfs_bmbt_set_blockcount(ep, temp);
- r[0] = *new;
- r[1].br_state = PREV.br_state;
- r[1].br_startblock = 0;
+ xfs_bmbt_set_blockcount(ep, temp); /* PREV becomes LEFT */
+ r[0] = *new; /* r[0] becomes MIDDLE */
+ r[1].br_state = PREV.br_state; /* r[1] is RIGHT */
+ r[1].br_startblock = nullstartblock(
+ (int)xfs_bmap_worst_indlen(ip, temp2));
r[1].br_startoff = new_endoff;
- temp2 = PREV.br_startoff + PREV.br_blockcount - new_endoff;
r[1].br_blockcount = temp2;
xfs_iext_insert(ip, idx + 1, 2, &r[0], state);
ip->i_df.if_lastex = idx + 1;
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