[PATCH AUTOSEL 5.17 14/20] ext4: fix warning when submitting superblock in ext4_commit_super()

Sasha Levin
2022-06-21T21:01:20Z

From: Zhang Yi <yi.zhang@huawei.com>

[ Upstream commit 15baa7dcadf1c4f0b4f752dc054191855ff2d78e ]

We have already check the io_error and uptodate flag before submitting
the superblock buffer, and re-set the uptodate flag if it has been
failed to write out. But it was lockless and could be raced by another
ext4_commit_super(), and finally trigger '!uptodate' WARNING when
marking buffer dirty. Fix it by submit buffer directly.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220520023216.3065073-1-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/super.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 3e6e618019a2..5da37cbe1176 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6006,7 +6006,6 @@ static void ext4_update_super(struct super_block *sb)
static int ext4_commit_super(struct super_block *sb)
{
struct buffer_head *sbh = EXT4_SB(sb)->s_sbh;
- int error = 0;

if (!sbh)
return -EINVAL;
@@ -6015,6 +6014,13 @@ static int ext4_commit_super(struct super_block *sb)

ext4_update_super(sb);

+ lock_buffer(sbh);
+ /* Buffer got discarded which means block device got invalidated */
+ if (!buffer_mapped(sbh)) {
+ unlock_buffer(sbh);
+ return -EIO;
+ }
+
if (buffer_write_io_error(sbh) || !buffer_uptodate(sbh)) {
/*
* Oh, dear. A previous attempt to write the
@@ -6029,17 +6035,21 @@ static int ext4_commit_super(struct super_block *sb)
clear_buffer_write_io_error(sbh);
set_buffer_uptodate(sbh);
}
- BUFFER_TRACE(sbh, "marking dirty");
- mark_buffer_dirty(sbh);
- error = __sync_dirty_buffer(sbh,
- REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0));
+ get_bh(sbh);
+ /* Clear potential dirty bit if it was journalled update */
+ clear_buffer_dirty(sbh);
+ sbh->b_end_io = end_buffer_write_sync;
+ submit_bh(REQ_OP_WRITE,
+ REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0), sbh);
+ wait_on_buffer(sbh);
if (buffer_write_io_error(sbh)) {
ext4_msg(sb, KERN_ERR, "I/O error while writing "
"superblock");
clear_buffer_write_io_error(sbh);
set_buffer_uptodate(sbh);
+ return -EIO;
}
- return error;
+ return 0;
}

/*
--
2.35.1