| Message ID | 20210615090537.3423231-1-yebin10@huawei.com |
|---|---|
| State | Awaiting Upstream |
| Headers | show |
| Series | [RFC,v2] ext4:fix warning in mark_buffer_dirty as IO error when mount with errors=continue | expand |
Thanks, applied. I reworded the commit description a bit, putting the
explanation first, and cleaning up the text a bit to make it more
readable:
commit 558d6450c7755aa005d89021204b6cdcae5e848f
Author: Ye Bin <yebin10@huawei.com>
Date: Tue Jun 15 17:05:37 2021 +0800
ext4: fix WARN_ON_ONCE(!buffer_uptodate) after an error writing the superblock
If a writeback of the superblock fails with an I/O error, the buffer
is marked not uptodate. However, this can cause a WARN_ON to trigger
when we attempt to write superblock a second time. (Which might
succeed this time, for cerrtain types of block devices such as iSCSI
devices over a flaky network.)
Try to detect this case in flush_stashed_error_work(), and also change
__ext4_handle_dirty_metadata() so we always set the uptodate flag, not
just in the nojournal case.
Before this commit, this problem can be repliciated via:
1. dmsetup create dust1 --table '0 2097152 dust /dev/sdc 0 4096'
2. mount /dev/mapper/dust1 /home/test
3. dmsetup message dust1 0 addbadblock 0 10
4. cd /home/test
5. echo "XXXXXXX" > t
After a few seconds, we got following warning:
... <rest of commit description was unchanged, and omitted here>
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c index be799040a415..b96ecba91899 100644 --- a/fs/ext4/ext4_jbd2.c +++ b/fs/ext4/ext4_jbd2.c @@ -327,6 +327,7 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line, set_buffer_meta(bh); set_buffer_prio(bh); + set_buffer_uptodate(bh); if (ext4_handle_valid(handle)) { err = jbd2_journal_dirty_metadata(handle, bh); /* Errors can only happen due to aborted journal or a nasty bug */ @@ -355,7 +356,6 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line, err); } } else { - set_buffer_uptodate(bh); if (inode) mark_buffer_dirty_inode(bh, inode); else diff --git a/fs/ext4/super.c b/fs/ext4/super.c index d29f6aa7d96e..67a92c11a45c 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -705,15 +705,23 @@ static void flush_stashed_error_work(struct work_struct *work) * ext4 error handling code during handling of previous errors. */ if (!sb_rdonly(sbi->s_sb) && journal) { + struct buffer_head *sbh = sbi->s_sbh; handle = jbd2_journal_start(journal, 1); if (IS_ERR(handle)) goto write_directly; - if (jbd2_journal_get_write_access(handle, sbi->s_sbh)) { + if (jbd2_journal_get_write_access(handle, sbh)) { jbd2_journal_stop(handle); goto write_directly; } ext4_update_super(sbi->s_sb); - if (jbd2_journal_dirty_metadata(handle, sbi->s_sbh)) { + if (buffer_write_io_error(sbh) || !buffer_uptodate(sbh)) { + ext4_msg(sbi->s_sb, KERN_ERR, "previous I/O error to " + "superblock detected"); + clear_buffer_write_io_error(sbh); + set_buffer_uptodate(sbh); + } + + if (jbd2_journal_dirty_metadata(handle, sbh)) { jbd2_journal_stop(handle); goto write_directly; }
We test with following step: 1. dmsetup create dust1 --table '0 2097152 dust /dev/sdc 0 4096' 2. mount /dev/mapper/dust1 /home/test 3. dmsetup message dust1 0 addbadblock 0 10 4. cd /home/test 5. echo "XXXXXXX" > t 6. wait a moment we got following warning: [ 80.654487] end_buffer_async_write: bh=0xffff88842f18bdd0 [ 80.656134] Buffer I/O error on dev dm-0, logical block 0, lost async page write [ 85.774450] EXT4-fs error (device dm-0): ext4_check_bdev_write_error:193: comm kworker/u16:8: Error while async write back metadata [ 91.415513] mark_buffer_dirty: bh=0xffff88842f18bdd0 [ 91.417038] ------------[ cut here ]------------ [ 91.418450] WARNING: CPU: 1 PID: 1944 at fs/buffer.c:1092 mark_buffer_dirty.cold+0x1c/0x5e [ 91.440322] Call Trace: [ 91.440652] __jbd2_journal_temp_unlink_buffer+0x135/0x220 [ 91.441354] __jbd2_journal_unfile_buffer+0x24/0x90 [ 91.441981] __jbd2_journal_refile_buffer+0x134/0x1d0 [ 91.442628] jbd2_journal_commit_transaction+0x249a/0x3240 [ 91.443336] ? put_prev_entity+0x2a/0x200 [ 91.443856] ? kjournald2+0x12e/0x510 [ 91.444324] kjournald2+0x12e/0x510 [ 91.444773] ? woken_wake_function+0x30/0x30 [ 91.445326] kthread+0x150/0x1b0 [ 91.445739] ? commit_timeout+0x20/0x20 [ 91.446258] ? kthread_flush_worker+0xb0/0xb0 [ 91.446818] ret_from_fork+0x1f/0x30 [ 91.447293] ---[ end trace 66f0b6bf3d1abade ]--- If super block write back with IO error, then will call clear_buffer_uptodate clear uptodate flag. But there is no chance to set buffer uptodate again. So call set_buffer_uptodate before call jbd2_journal_dirty_metadata to make sure that buffer is uptodate when buffer is jbddirty. Signed-off-by: Ye Bin <yebin10@huawei.com> --- fs/ext4/ext4_jbd2.c | 2 +- fs/ext4/super.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 3 deletions(-)