From a634c0a60b9c7942630b4f68b0af55c62d74b8fc Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 10 Aug 2023 07:48:11 -0700 Subject: [PATCH] xfs: fix agf_fllast when repairing an empty AGFL xfs/139 with parent pointers enabled occasionally pops up a corruption message when online fsck force-rebuild repairs an AGFL: XFS (sde): Metadata corruption detected at xfs_agf_verify+0x11e/0x220 [xfs], xfs_agf block 0x9e0001 XFS (sde): Unmount and run xfs_repair XFS (sde): First 128 bytes of corrupted metadata buffer: 00000000: 58 41 47 46 00 00 00 01 00 00 00 4f 00 00 40 00 XAGF.......O..@. 00000010: 00 00 00 01 00 00 00 02 00 00 00 05 00 00 00 01 ................ 00000020: 00 00 00 01 00 00 00 01 00 00 00 00 ff ff ff ff ................ 00000030: 00 00 00 00 00 00 00 05 00 00 00 05 00 00 00 00 ................ 00000040: 91 2e 6f b1 ed 61 4b 4d 8c 9b 6e 87 08 bb f6 36 ..o..aKM..n....6 00000050: 00 00 00 01 00 00 00 01 00 00 00 06 00 00 00 01 ................ 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ The root cause of this failure is that prior to the repair, there were zero blocks in the AGFL. This scenario is set up by the test case, since it formats with 64MB AGs and tries to ENOSPC the whole filesystem. In this case of flcount==0, we reset fllast to -1U, which then trips the write verifier's check that fllast is less than xfs_agfl_size(). Correct this code to set fllast to the last possible slot in the AGFL when flcount is zero, which mirrors the behavior of xfs_repair phase5 when it has to create a totally empty AGFL. Fixes: 0e93d3f43ec7 ("xfs: repair the AGFL") Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner --- fs/xfs/scrub/agheader_repair.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c index 6fbb31f..876a2f4 100644 --- a/fs/xfs/scrub/agheader_repair.c +++ b/fs/xfs/scrub/agheader_repair.c @@ -627,7 +627,10 @@ xrep_agfl_update_agf( } agf->agf_flfirst = cpu_to_be32(0); agf->agf_flcount = cpu_to_be32(flcount); - agf->agf_fllast = cpu_to_be32(flcount - 1); + if (flcount) + agf->agf_fllast = cpu_to_be32(flcount - 1); + else + agf->agf_fllast = cpu_to_be32(xfs_agfl_size(sc->mp) - 1); xfs_alloc_log_agf(sc->tp, agf_bp, XFS_AGF_FLFIRST | XFS_AGF_FLLAST | XFS_AGF_FLCOUNT); -- 2.7.4