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120 lines
4.4 KiB
120 lines
4.4 KiB
1 year ago
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From b827e2318ea2bb3eabca13a965c2535a1d7289e5 Mon Sep 17 00:00:00 2001
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From: Long Li <leo.lilong@huawei.com>
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Date: Fri, 18 Nov 2022 12:23:57 +0100
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Subject: [PATCH] xfs: fix sb write verify for lazysbcount
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Source kernel commit: 7cecd500d90164419add650e26cc1de03a7a66cb
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When lazysbcount is enabled, fsstress and loop mount/unmount test report
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the following problems:
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XFS (loop0): SB summary counter sanity check failed
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XFS (loop0): Metadata corruption detected at xfs_sb_write_verify+0x13b/0x460,
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xfs_sb block 0x0
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XFS (loop0): Unmount and run xfs_repair
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XFS (loop0): First 128 bytes of corrupted metadata buffer:
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00000000: 58 46 53 42 00 00 10 00 00 00 00 00 00 28 00 00 XFSB.........(..
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00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
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00000020: 69 fb 7c cd 5f dc 44 af 85 74 e0 cc d4 e3 34 5a i.|._.D..t....4Z
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00000030: 00 00 00 00 00 20 00 06 00 00 00 00 00 00 00 80 ..... ..........
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00000040: 00 00 00 00 00 00 00 81 00 00 00 00 00 00 00 82 ................
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00000050: 00 00 00 01 00 0a 00 00 00 00 00 04 00 00 00 00 ................
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00000060: 00 00 0a 00 b4 b5 02 00 02 00 00 08 00 00 00 00 ................
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00000070: 00 00 00 00 00 00 00 00 0c 09 09 03 14 00 00 19 ................
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XFS (loop0): Corruption of in-memory data (0x8) detected at _xfs_buf_ioapply
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+0xe1e/0x10e0 (fs/xfs/xfs_buf.c:1580). Shutting down filesystem.
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XFS (loop0): Please unmount the filesystem and rectify the problem(s)
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XFS (loop0): log mount/recovery failed: error -117
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XFS (loop0): log mount failed
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This corruption will shutdown the file system and the file system will
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no longer be mountable. The following script can reproduce the problem,
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but it may take a long time.
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#!/bin/bash
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device=/dev/sda
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testdir=/mnt/test
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round=0
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function fail()
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{
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echo "$*"
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exit 1
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}
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mkdir -p $testdir
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while [ $round -lt 10000 ]
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do
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echo "******* round $round ********"
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mkfs.xfs -f $device
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mount $device $testdir || fail "mount failed!"
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fsstress -d $testdir -l 0 -n 10000 -p 4 >/dev/null &
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sleep 4
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killall -w fsstress
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umount $testdir
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xfs_repair -e $device > /dev/null
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if [ $? -eq 2 ];then
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echo "ERR CODE 2: Dirty log exception during repair."
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exit 1
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fi
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round=$(($round+1))
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done
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With lazysbcount is enabled, There is no additional lock protection for
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reading m_ifree and m_icount in xfs_log_sb(), if other cpu modifies the
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m_ifree, this will make the m_ifree greater than m_icount. For example,
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consider the following sequence and ifreedelta is postive:
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CPU0 CPU1
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xfs_log_sb xfs_trans_unreserve_and_mod_sb
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---------- ------------------------------
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percpu_counter_sum(&mp->m_icount)
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percpu_counter_add_batch(&mp->m_icount,
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idelta, XFS_ICOUNT_BATCH)
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percpu_counter_add(&mp->m_ifree, ifreedelta);
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percpu_counter_sum(&mp->m_ifree)
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After this, incorrect inode count (sb_ifree > sb_icount) will be writen to
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the log. In the subsequent writing of sb, incorrect inode count (sb_ifree >
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sb_icount) will fail to pass the boundary check in xfs_validate_sb_write()
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that cause the file system shutdown.
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When lazysbcount is enabled, we don't need to guarantee that Lazy sb
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counters are completely correct, but we do need to guarantee that sb_ifree
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<= sb_icount. On the other hand, the constraint that m_ifree <= m_icount
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must be satisfied any time that there /cannot/ be other threads allocating
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or freeing inode chunks. If the constraint is violated under these
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circumstances, sb_i{count,free} (the ondisk superblock inode counters)
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maybe incorrect and need to be marked sick at unmount, the count will
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be rebuilt on the next mount.
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Fixes: 8756a5af1819 ("libxfs: add more bounds checking to sb sanity checks")
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Signed-off-by: Long Li <leo.lilong@huawei.com>
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Reviewed-by: Darrick J. Wong <djwong@kernel.org>
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Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Signed-off-by: Pavel Reichl <preichl@redhat.com>
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---
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libxfs/xfs_sb.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/libxfs/xfs_sb.c b/libxfs/xfs_sb.c
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index fc33dc4a..d05f0e6e 100644
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--- a/libxfs/xfs_sb.c
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+++ b/libxfs/xfs_sb.c
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@@ -970,7 +970,9 @@ xfs_log_sb(
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*/
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if (xfs_has_lazysbcount(mp)) {
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mp->m_sb.sb_icount = percpu_counter_sum(&mp->m_icount);
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- mp->m_sb.sb_ifree = percpu_counter_sum(&mp->m_ifree);
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+ mp->m_sb.sb_ifree = min_t(uint64_t,
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+ percpu_counter_sum(&mp->m_ifree),
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+ mp->m_sb.sb_icount);
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mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
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}
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--
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2.40.0
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