From: Zheng Bin zhengbin13@huawei.com

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@huawei.com Signed-off-by: Ren Xudong renxudong1@huawei.com Reviewed-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: Darrick J. Wong darrick.wong@oracle.com (cherry picked from commit d0c7feaf87678371c2c09b3709400be416b2dc62) --- 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 516e0c57cf9c..43c87cb5a747 100644 --- a/fs/xfs/libxfs/xfs_alloc.c +++ b/fs/xfs/libxfs/xfs_alloc.c @@ -2529,6 +2529,13 @@ xfs_agf_verify( be32_to_cpu(agf->agf_flcount) <= xfs_agfl_size(mp))) return false;

+ 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 || @@ -2540,6 +2547,10 @@ xfs_agf_verify( be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) > XFS_BTREE_MAXLEVELS)) return false;

+ 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 @@ -2553,6 +2564,11 @@ xfs_agf_verify( be32_to_cpu(agf->agf_btreeblks) > be32_to_cpu(agf->agf_length)) return false;

+ 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))