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Theodore Ts'o

2013-Dec-02 14:45 UTC

[Ocfs2-devel] [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space

If a handle runs out of space, we currently stop the kernel with a
BUG.  This makes it hard to figure out what might be going on.  So
return an error of ENOSPC, so we can let the file system layer figure
out what is going on, to make it more likely we can get useful
debugging information).  This should make it easier to debug problems
such as the one which was reported by:

    https://bugzilla.kernel.org/show_bug.cgi?id=44731

The only two callers of this function are ext4_handle_dirty_metadata()
and ocfs2_journal_dirty().  The ocfs2 function will trigger a
BUG_ON(), which means there will be no change in behavior.  The ext4
function will call ext4_error_inode() which will print the useful
debugging information and then handle the situation using ext4's error
handling mechanisms (i.e., which might mean halting the kernel or
remounting the file system read-only).

Also, since both file systems already call WARN_ON(), drop the WARN_ON
from jbd2_journal_dirty_metadata() to avoid two stack traces from
being displayed.

Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
Cc: ocfs2-devel at oss.oracle.com
---
 fs/jbd2/transaction.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 7aa9a32..b0b74e5 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1290,7 +1290,10 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct
buffer_head *bh)
 		 * once a transaction -bzzz
 		 */
 		jh->b_modified = 1;
-		J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
+		if (handle->h_buffer_credits <= 0) {
+			ret = -ENOSPC;
+			goto out_unlock_bh;
+		}
 		handle->h_buffer_credits--;
 	}
 
@@ -1373,7 +1376,6 @@ out_unlock_bh:
 	jbd2_journal_put_journal_head(jh);
 out:
 	JBUFFER_TRACE(jh, "exit");
-	WARN_ON(ret);	/* All errors are bugs, so dump the stack */
 	return ret;
 }
 
-- 
1.8.5.rc3.362.gdf10213

Jan Kara

2013-Dec-02 15:35 UTC

head link

[Ocfs2-devel] [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space

On Mon 02-12-13 09:45:02, Ted Tso wrote:> If a handle runs out of space, we currently stop the kernel with a
> BUG.  This makes it hard to figure out what might be going on.  So
> return an error of ENOSPC, so we can let the file system layer figure
> out what is going on, to make it more likely we can get useful
> debugging information).  This should make it easier to debug problems
> such as the one which was reported by:
> 
>     https://bugzilla.kernel.org/show_bug.cgi?id=44731
> 
> The only two callers of this function are ext4_handle_dirty_metadata()
> and ocfs2_journal_dirty().  The ocfs2 function will trigger a
> BUG_ON(), which means there will be no change in behavior.  The ext4
> function will call ext4_error_inode() which will print the useful
> debugging information and then handle the situation using ext4's error
> handling mechanisms (i.e., which might mean halting the kernel or
> remounting the file system read-only).
> 
> Also, since both file systems already call WARN_ON(), drop the WARN_ON
> from jbd2_journal_dirty_metadata() to avoid two stack traces from
> being displayed.
> 
> Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
> Cc: ocfs2-devel at oss.oracle.com  The patch looks good. You can add:
Reviewed-by: Jan Kara <jack at suse.cz>

								Honza
> ---
>  fs/jbd2/transaction.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index 7aa9a32..b0b74e5 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -1290,7 +1290,10 @@ int jbd2_journal_dirty_metadata(handle_t *handle,
struct buffer_head *bh)
>  		 * once a transaction -bzzz
>  		 */
>  		jh->b_modified = 1;
> -		J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
> +		if (handle->h_buffer_credits <= 0) {
> +			ret = -ENOSPC;
> +			goto out_unlock_bh;
> +		}
>  		handle->h_buffer_credits--;
>  	}
>  
> @@ -1373,7 +1376,6 @@ out_unlock_bh:
>  	jbd2_journal_put_journal_head(jh);
>  out:
>  	JBUFFER_TRACE(jh, "exit");
> -	WARN_ON(ret);	/* All errors are bugs, so dump the stack */
>  	return ret;
>  }
>  
> -- 
> 1.8.5.rc3.362.gdf10213
> 
> --
> To unsubscribe from this list: send the line "unsubscribe
linux-ext4" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html-- 
Jan Kara <jack at suse.cz>
SUSE Labs, CR

Joel Becker

2013-Dec-03 07:34 UTC

head link

[Ocfs2-devel] [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space

On Mon, Dec 02, 2013 at 09:45:02AM -0500, Theodore Ts'o
wrote:> If a handle runs out of space, we currently stop the kernel with a
> BUG.  This makes it hard to figure out what might be going on.  So
> return an error of ENOSPC, so we can let the file system layer figure
> out what is going on, to make it more likely we can get useful
> debugging information).  This should make it easier to debug problems
> such as the one which was reported by:
> 
>     https://bugzilla.kernel.org/show_bug.cgi?id=44731
> 
> The only two callers of this function are ext4_handle_dirty_metadata()
> and ocfs2_journal_dirty().  The ocfs2 function will trigger a
> BUG_ON(), which means there will be no change in behavior.  The ext4
> function will call ext4_error_inode() which will print the useful
> debugging information and then handle the situation using ext4's error
> handling mechanisms (i.e., which might mean halting the kernel or
> remounting the file system read-only).
> 
> Also, since both file systems already call WARN_ON(), drop the WARN_ON
> from jbd2_journal_dirty_metadata() to avoid two stack traces from
> being displayed.
> 
> Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
> Cc: ocfs2-devel at oss.oracle.com
Acked-by: Joel Becker <jlbec at evilplan.org>
> ---
>  fs/jbd2/transaction.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index 7aa9a32..b0b74e5 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -1290,7 +1290,10 @@ int jbd2_journal_dirty_metadata(handle_t *handle,
struct buffer_head *bh)
>  		 * once a transaction -bzzz
>  		 */
>  		jh->b_modified = 1;
> -		J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
> +		if (handle->h_buffer_credits <= 0) {
> +			ret = -ENOSPC;
> +			goto out_unlock_bh;
> +		}
>  		handle->h_buffer_credits--;
>  	}
>  
> @@ -1373,7 +1376,6 @@ out_unlock_bh:
>  	jbd2_journal_put_journal_head(jh);
>  out:
>  	JBUFFER_TRACE(jh, "exit");
> -	WARN_ON(ret);	/* All errors are bugs, so dump the stack */
>  	return ret;
>  }
>  
> -- 
> 1.8.5.rc3.362.gdf10213
> 
> --
> To unsubscribe from this list: send the line "unsubscribe
linux-ext4" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
--

Ocfs2 devel - Dec 2013 - [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space

[Ocfs2-devel] [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space

[Ocfs2-devel] [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space

[Ocfs2-devel] [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space