Hi Ted,
On 2025/1/3 23:54, Theodore Ts'o wrote:
On Fri, Jan 03, 2025 at 10:35:17AM -0500, Theodore Ts'o wrote:
I don't see how setting the shutdown flag causes reads to fail. That
was true in an early version of the ext4 patch which implemented
shutdown support, but one of the XFS developers (I don't remember if
it was Dave or Cristoph) objected because XFS did not cause the
read_pages function to fail. Are you seeing this with an upstream
kernel, or with a patched kernel? The upstream kernel does *not* have
the check in ext4_readpages() or ext4_read_folio() (post folio
conversion).
OK, that's weird. Testing on 6.13-rc4, I don't see the problem simulating an ext4 error:
root@kvm-xfstests:~# mke2fs -t ext4 -Fq /dev/vdc
/dev/vdc contains a ext4 file system
last mounted on /vdc on Fri Jan 3 10:38:21 2025
root@kvm-xfstests:~# mount -t ext4 -o errors=continue /dev/vdc /vdc
We are discussing "errors=remount-ro," as the title states, not the
continue mode. The key code leading to the behavior change is as follows,
therefore the continue mode is not affected.
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -657,7 +657,7 @@ static void ext4_handle_error(struct super_block
*sb, bool force_ro, int error,
WARN_ON_ONCE(1);
if (!continue_fs && !sb_rdonly(sb)) {
- ext4_set_mount_flag(sb, EXT4_MF_FS_ABORTED);
+ set_bit(EXT4_FLAGS_SHUTDOWN, &EXT4_SB(sb)->s_ext4_flags);
if (journal)
jbd2_journal_abort(journal, -EIO);
}
See the end for problem reproduction.
[ 24.780982] EXT4-fs (vdc): mounted filesystem f8595206-fe57-486c-80dd-48b03d41ebdb r/w with ordered data mode. Quota mode: none.
root@kvm-xfstests:~# cp /etc/motd /vdc/motd
root@kvm-xfstests:~# echo testing > /sys/fs/ext4/vdc/trigger_fs_error
[ 42.943141] EXT4-fs error (device vdc): trigger_test_error:129: comm bash: testing
root@kvm-xfstests:~# cat /vdc/motd
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
root@kvm-xfstests:~#
HOWEVER, testing with shutdown ioctl, both ext4 and xfs are failing with EIO:
Yes, this is as expected.
root@kvm-xfstests:~# mount /dev/vdc /vdc
[ 7.969168] XFS (vdc): Mounting V5 Filesystem 7834ea96-eab0-46c5-9b18-c8f054fa9cf4
[ 7.978539] XFS (vdc): Ending clean mount
root@kvm-xfstests:~# cp /etc/motd /vdc
root@kvm-xfstests:~# /root/xfstests/src/godown -v /vdc
Opening "/vdc"
Calling XFS_IOC_GOINGDOWN
[ 29.354609] XFS (vdc): User initiated shutdown received.
[ 29.356123] XFS (vdc): Log I/O Error (0x6) detected at xfs_fs_goingdown+0x55/0xb0 (fs/xfs/xfs_fsops.c:452). Shutting down filesystem.
[ 29.357092] XFS (vdc): Please unmount the filesystem and rectify the problem(s)
root@kvm-xfstests:~# cat /vdc/motd
cat: /vdc/motd: Input/output error
root@kvm-xfstests:~#
So I take back what I said earlier, but I am a bit confused why it
worked after simulating an file system error using "echo testing >
/sys/fs/ext4/vdc/trigger_fs_error".
It's because "errors=remount-ro" wasn't used when mounting...
Here's a replication:
root@kvm-xfstests:~# mount -o errors=remount-ro /dev/vdc /mnt/test
[ 115.731007] EXT4-fs (vdc): mounted filesystem
0838f08f-c04e-440c-a9a5-417677efb03e r/w with ordered data mode. Quota
mode: none.
root@kvm-xfstests:~# echo test > /mnt/test/file
root@kvm-xfstests:~# cat /mnt/test/file
test
root@kvm-xfstests:~# echo 1 > /sys/fs/ext4/vdc/trigger_fs_error
[ 131.537649] EXT4-fs error (device vdc): trigger_test_error:129: comm
bash: 1
[ 131.538226] Aborting journal on device vdc-8.
[ 131.538844] EXT4-fs (vdc): Remounting filesystem read-only
root@kvm-xfstests:~# cat /mnt/test/file
cat: /mnt/test/file: Input/output error
root@kvm-xfstests:~# uname -a
Linux kvm-xfstests 6.13.0-rc4-xfstests-g6cfe3548f8f5-dirty #284 SMP
PREEMPT_DYNAMIC Fri Dec 27 10:39:02 CST 2024 x86_64 GNU/Linux
Regards,
Baokun
