[PATCH RFC] ext4:fix warning in mark_buffer_dirty as IO error when mount with errors=continue

From: Ye Bin
Date: Mon Jun 14 2021 - 23:18:26 EST


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@xxxxxxxxxx>
---
fs/ext4/ext4_jbd2.c | 2 +-
fs/ext4/super.c | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)

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..1bd50d3d6a47 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5584,6 +5584,7 @@ static void ext4_update_super(struct super_block *sb)
spin_unlock(&sbi->s_error_lock);

ext4_superblock_csum_set(sb);
+ set_buffer_uptodate(sbh);
unlock_buffer(sbh);
}

--
2.31.1