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[2/5] jbd2: don't mark block as modified if the handle is out of credits

Message ID 20180618032232.25481-2-tytso@mit.edu
State Accepted, archived
Headers show
Series [1/5] ext4: never move the system.data xattr out of the inode body | expand

Commit Message

Theodore Ts'o June 18, 2018, 3:22 a.m. UTC
Do not set the b_modified flag in block's journal head should not
until after we're sure that jbd2_journal_dirty_metadat() will not
abort with an error due to there not being enough space reserved in
the jbd2 handle.

Otherwise, future attempts to modify the buffer may lead a large
number of spurious errors and warnings.

https://bugzilla.kernel.org/show_bug.cgi?id=200071

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/jbd2/transaction.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Comments

Andreas Dilger June 18, 2018, 6:27 p.m. UTC | #1
> On Jun 17, 2018, at 9:22 PM, Theodore Ts'o <tytso@mit.edu> wrote:
> 
> Do not set the b_modified flag in block's journal head should not
> until after we're sure that jbd2_journal_dirty_metadat() will not
> abort with an error due to there not being enough space reserved in
> the jbd2 handle.

Looks like you partially edited this sentence after it was written,
but didn't get it back to coherency?

> Otherwise, future attempts to modify the buffer may lead a large
> number of spurious errors and warnings.

... lead *to* a large number ...

> 
> https://bugzilla.kernel.org/show_bug.cgi?id=200071
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
> fs/jbd2/transaction.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index 51dd68e67b0f..c0b66a7a795b 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -1361,6 +1361,13 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
> 		if (jh->b_transaction == transaction &&
> 		    jh->b_jlist != BJ_Metadata) {
> 			jbd_lock_bh_state(bh);
> +			if (jh->b_transaction == transaction &&
> +			    jh->b_jlist != BJ_Metadata)
> +				pr_err("JBD2: assertion failure: h_type=%u "
> +				       "h_line_no=%u block_no=%llu jlist=%u\n",
> +				       handle->h_type, handle->h_line_no,
> +				       (unsigned long long) bh->b_blocknr,
> +				       jh->b_jlist);
> 			J_ASSERT_JH(jh, jh->b_transaction != transaction ||
> 					jh->b_jlist == BJ_Metadata);

Should the J_ASSERT_JH() be inside the second "if" block that is rechecked
under lock?  Otherwise, I don't see the point in getting the bh_state lock
since either jh->b_jlist can't change and there is no need to lock it, or
it *can* change and we shouldn't assert if the condition is no longer wrong
enough to print the error message.

> 			jbd_unlock_bh_state(bh);
> @@ -1380,11 +1387,11 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
> 		 * of the transaction. This needs to be done
> 		 * once a transaction -bzzz
> 		 */
> -		jh->b_modified = 1;
> 		if (handle->h_buffer_credits <= 0) {
> 			ret = -ENOSPC;
> 			goto out_unlock_bh;
> 		}
> +		jh->b_modified = 1;
> 		handle->h_buffer_credits--;
> 	}
> 
> --
> 2.18.0.rc0
> 


Cheers, Andreas
diff mbox series

Patch

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 51dd68e67b0f..c0b66a7a795b 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1361,6 +1361,13 @@  int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
 		if (jh->b_transaction == transaction &&
 		    jh->b_jlist != BJ_Metadata) {
 			jbd_lock_bh_state(bh);
+			if (jh->b_transaction == transaction &&
+			    jh->b_jlist != BJ_Metadata)
+				pr_err("JBD2: assertion failure: h_type=%u "
+				       "h_line_no=%u block_no=%llu jlist=%u\n",
+				       handle->h_type, handle->h_line_no,
+				       (unsigned long long) bh->b_blocknr,
+				       jh->b_jlist);
 			J_ASSERT_JH(jh, jh->b_transaction != transaction ||
 					jh->b_jlist == BJ_Metadata);
 			jbd_unlock_bh_state(bh);
@@ -1380,11 +1387,11 @@  int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
 		 * of the transaction. This needs to be done
 		 * once a transaction -bzzz
 		 */
-		jh->b_modified = 1;
 		if (handle->h_buffer_credits <= 0) {
 			ret = -ENOSPC;
 			goto out_unlock_bh;
 		}
+		jh->b_modified = 1;
 		handle->h_buffer_credits--;
 	}