From: Ye Bin <yebin10@xxxxxxxxxx> [ Upstream commit 558d6450c7755aa005d89021204b6cdcae5e848f ] 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: [ 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 ]--- Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210615090537.3423231-1-yebin10@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/ext4/ext4_jbd2.c | 2 +- fs/ext4/super.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 3 deletions(-) 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 62dd98189e32..265745154945 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; } -- 2.30.2
