We recently used fuzz(hydra) to test XFS and automatically generate
tmp.img(XFS v5 format, but some metadata is wrong)
xfs_repair information(just one AG):
agf_freeblks 0, counted 3224 in ag 0
agf_longest 536874136, counted 3224 in ag 0
sb_fdblocks 613, counted 3228
Test as follows:
mount tmp.img tmpdir
cp file1M tmpdir
sync
In 4.19-stable, sync will stuck, the reason is:
xfs_mountfs
xfs_check_summary_counts
if ((!xfs_sb_version_haslazysbcount(&mp->m_sb) ||
XFS_LAST_UNMOUNT_WAS_CLEAN(mp)) &&
!xfs_fs_has_sickness(mp, XFS_SICK_FS_COUNTERS))
return 0; -->just return, incore sb_fdblocks still be 613
xfs_initialize_perag_data
cp file1M tmpdir -->ok(write file to pagecache)
sync -->stuck(write pagecache to disk)
xfs_map_blocks
xfs_iomap_write_allocate
while (count_fsb != 0) {
nimaps = 0;
while (nimaps == 0) { --> endless loop
nimaps = 1;
xfs_bmapi_write(..., &nimaps) --> nimaps becomes 0 again
xfs_bmapi_write
xfs_bmap_alloc
xfs_bmap_btalloc
xfs_alloc_vextent
xfs_alloc_fix_freelist
xfs_alloc_space_available -->fail(agf_freeblks is 0)
In linux-next, sync not stuck, cause commit c2b3164320b5 ("xfs:
use the latest extent at writeback delalloc conversion time") remove
the above while, dmesg is as follows:
[ 55.250114] XFS (loop0): page discard on page ffffea0008bc7380, inode 0x1b0c, offset 0.
Users do not know why this page is discard, the better soultion is:
1. Like xfs_repair, make sure sb_fdblocks is equal to counted
(xfs_initialize_perag_data did this, who is not called at this mount)
2. Add agf verify, if fail, will tell users to repair
This patch use the second soultion.
Signed-off-by: Zheng Bin <zhengbin13@xxxxxxxxxx>
Signed-off-by: Ren Xudong <renxudong1@xxxxxxxxxx>
---
v1->v2: modify comment, add more agf verify
v2->v3: modify code which is suggested by hellwig & darrick
besides, remove the agf_freeblks < sb_fdblocks check, sb_fdblocks may not be true,
if we have lazysbcount or not umount clean. If we check this, we need to add
if ((!xfs_sb_version_haslazysbcount(&mp->m_sb) ||
XFS_LAST_UNMOUNT_WAS_CLEAN(mp)) &&
!xfs_fs_has_sickness(mp, XFS_SICK_FS_COUNTERS))
like function xfs_check_summary_counts does.
fs/xfs/libxfs/xfs_alloc.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index d8053bc..183dc25 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2858,6 +2858,13 @@ xfs_agf_verify(
be32_to_cpu(agf->agf_flcount) <= xfs_agfl_size(mp)))
return __this_address;
+ if (be32_to_cpu(agf->agf_length) > mp->m_sb.sb_dblocks)
+ return __this_address;
+
+ if (be32_to_cpu(agf->agf_freeblks) < be32_to_cpu(agf->agf_longest) ||
+ be32_to_cpu(agf->agf_freeblks) > be32_to_cpu(agf->agf_length))
+ return __this_address;
+
if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) < 1 ||
be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]) < 1 ||
be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) > XFS_BTREE_MAXLEVELS ||
@@ -2869,6 +2876,10 @@ xfs_agf_verify(
be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) > XFS_BTREE_MAXLEVELS))
return __this_address;
+ if (xfs_sb_version_hasrmapbt(&mp->m_sb) &&
+ be32_to_cpu(agf->agf_rmap_blocks) > be32_to_cpu(agf->agf_length))
+ return __this_address;
+
/*
* during growfs operations, the perag is not fully initialised,
* so we can't use it for any useful checking. growfs ensures we can't
@@ -2883,6 +2894,11 @@ xfs_agf_verify(
return __this_address;
if (xfs_sb_version_hasreflink(&mp->m_sb) &&
+ be32_to_cpu(agf->agf_refcount_blocks) >
+ be32_to_cpu(agf->agf_length))
+ return __this_address;
+
+ if (xfs_sb_version_hasreflink(&mp->m_sb) &&
(be32_to_cpu(agf->agf_refcount_level) < 1 ||
be32_to_cpu(agf->agf_refcount_level) > XFS_BTREE_MAXLEVELS))
return __this_address;
--
2.7.4
