[PATCH] ext3/jbd: Avoid WARN() messages when failing to write to the superblock

[PATCH] ext3/jbd: Avoid WARN() messages when failing to write to the superblock

[Theodore Ts'o]

This fixes some very common warnings reported by kerneloops.org

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 fs/ext3/super.c  |   23 ++++++++++++++++++++++-
 fs/jbd/journal.c |   29 +++++++++++++++++++++++++++--
 2 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index f38a5af..b3f8eb8 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2259,13 +2259,34 @@ static void ext3_commit_super (struct super_block * sb,
 
 	if (!sbh)
 		return;
+	if (buffer_write_io_error(sbh)) {
+		/*
+		 * Oh, dear.  A previous attempt to write the
+		 * superblock failed.  This could happen because the
+		 * USB device was yanked out.  Or it could happen to
+		 * be a transient write error and maybe the block will
+		 * be remapped.  Nothing we can do but to retry the
+		 * write and hope for the best.
+		 */
+		printk(KERN_ERR "ext3: previous I/O error to "
+		       "superblock detected for %s.\n", sb->s_id);
+		clear_buffer_write_io_error(sbh);
+		set_buffer_uptodate(sbh);
+	}
 	es->s_wtime = cpu_to_le32(get_seconds());
 	es->s_free_blocks_count = cpu_to_le32(ext3_count_free_blocks(sb));
 	es->s_free_inodes_count = cpu_to_le32(ext3_count_free_inodes(sb));
 	BUFFER_TRACE(sbh, "marking dirty");
 	mark_buffer_dirty(sbh);
-	if (sync)
+	if (sync) {
 		sync_dirty_buffer(sbh);
+		if (buffer_write_io_error(sbh)) {
+			printk(KERN_ERR "ext3: I/O error while writing "
+			       "superblock for %s.\n", sb->s_id);
+			clear_buffer_write_io_error(sbh);
+			set_buffer_uptodate(sbh);
+		}
+	}
 }
 
 
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index aa7143a..8214175 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -83,6 +83,7 @@ EXPORT_SYMBOL(journal_force_commit);
 
 static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
 static void __journal_abort_soft (journal_t *journal, int errno);
+static const char *journal_dev_name(journal_t *journal, char *buffer);
 
 /*
  * Helper function used to manage commit timeouts
@@ -931,6 +932,7 @@ void journal_update_superblock(journal_t *journal, int wait)
 {
 	journal_superblock_t *sb = journal->j_superblock;
 	struct buffer_head *bh = journal->j_sb_buffer;
+	char b[BDEVNAME_SIZE];
 
 	/*
 	 * As a special case, if the on-disk copy is already marked as needing
@@ -948,6 +950,22 @@ void journal_update_superblock(journal_t *journal, int wait)
 		goto out;
 	}
 
+	if (buffer_write_io_error(bh)) {
+		/*
+		 * Oh, dear.  A previous attempt to write the journal
+		 * superblock failed.  This could happen because the
+		 * USB device was yanked out.  Or it could happen to
+		 * be a transient write error and maybe the block will
+		 * be remapped.  Nothing we can do but to retry the
+		 * write and hope for the best.
+		 */
+		printk(KERN_ERR "JBD: previous I/O error detected "
+		       "for journal superblock update for %s.\n",
+		       journal_dev_name(journal, b));
+		clear_buffer_write_io_error(bh);
+		set_buffer_uptodate(bh);
+	}
+
 	spin_lock(&journal->j_state_lock);
 	jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
 		  journal->j_tail, journal->j_tail_sequence, journal->j_errno);
@@ -959,9 +977,16 @@ void journal_update_superblock(journal_t *journal, int wait)
 
 	BUFFER_TRACE(bh, "marking dirty");
 	mark_buffer_dirty(bh);
-	if (wait)
+	if (wait) {
 		sync_dirty_buffer(bh);
-	else
+		if (buffer_write_io_error(bh)) {
+			printk(KERN_ERR "JBD: I/O error detected "
+			       "when updating journal superblock for %s.\n",
+			       journal_dev_name(journal, b));
+			clear_buffer_write_io_error(bh);
+			set_buffer_uptodate(bh);
+		}
+	} else
 		ll_rw_block(SWRITE, 1, &bh);
 
 out:
-- 
1.5.6.1.205.ge2c7.dirty

Re: [PATCH] ext3/jbd: Avoid WARN() messages when failing to write to the superblock

[Arjan van de Ven]

On Sat, 20 Sep 2008 17:35:47 -0400
Theodore Ts'o <tytso@mit.edu> wrote:

> This fixes some very common warnings reported by kerneloops.org

just to quantify "very common"; I did a quick count on the database and
there have been 4920 reports of the WARNing fixed by this patch...
that's quite a bit.


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org

Re: [PATCH] ext3/jbd: Avoid WARN() messages when failing to write to the superblock

[Jan Kara]

> This fixes some very common warnings reported by kerneloops.org
> 
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  The patch looks nice but does it really fix the warnings? I see
at least ext3_put_super() calling mark_buffer_dirty() before calling
ext3_commit_super(). We should just remove that mark_buffer_dirty()
call.
  BTW: Do you plan doing a similar fix for ext2 and ext4?

								Honza
-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs

Re: [PATCH] ext3/jbd: Avoid WARN() messages when failing to write to the superblock

[Theodore Tso]

On Sun, Sep 21, 2008 at 07:33:28PM +0200, Jan Kara wrote:
> > This fixes some very common warnings reported by kerneloops.org
> > 
> > Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
>   The patch looks nice but does it really fix the warnings? I see
> at least ext3_put_super() calling mark_buffer_dirty() before calling
> ext3_commit_super(). We should just remove that mark_buffer_dirty()
> call.

I tested it, and in practice it works, since mark_buffer_dirty() only
causes a problem if an attempt to write to the superblock has already
failed.  I agree that we should just remove that mark_buffer_dirty()
call, though, since ext3_put_super() calls ext3_commit_super() which
calls mark_buffer_dirty() anyway.  I'll respin the patch.

>   BTW: Do you plan doing a similar fix for ext2 and ext4?

I have a similar fix for ext4 that is queued up to be pushed once the
merge window opens.  I haven't back-ported it to ext2 yet, but I will.

						- Ted