Re: [PATCH] ext3: Don't warn from writepage when readonly inode is spotted after error

Jan Kara
2011-12-22T16:19:14Z

On Thu 22-12-11 10:11:36, Eric Sandeen wrote:
> On 12/22/11 9:56 AM, Jan Kara wrote:
> > WARN_ON_ONCE(IS_RDONLY(inode)) tends to trip when filesystem hits error and is
> > remounted read-only. This unnecessarily scares users (well, they should be
> > scared because of filesystem error, but the stack trace distracts them from the
> > right source of their fear ;-). We could as well just remove the WARN_ON but
> > it's not hard to fix it to not trip on filesystem with errors and not use more
> > cycles in the common case so that's what we do.
>
> I've seen that too and it is distracting.
>
> Looks good to me, aside from the rather long lines ;)
Ah, right. My internal style checker had a coffee break I assume ;).
Below is a version with long lines fixed.

Honza

>From 0588350bf10c8dad70cc299971dfdeec10754b29 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Thu, 22 Dec 2011 16:49:05 +0100
Subject: [PATCH] ext3: Don't warn from writepage when readonly inode is spotted after error

WARN_ON_ONCE(IS_RDONLY(inode)) tends to trip when filesystem hits error and is
remounted read-only. This unnecessarily scares users (well, they should be
scared because of filesystem error, but the stack trace distracts them from the
right source of their fear ;-). We could as well just remove the WARN_ON but
it's not hard to fix it to not trip on filesystem with errors and not use more
cycles in the common case so that's what we do.

CC: stable@kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/ext3/inode.c | 24 +++++++++++++++++++++---
1 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index a8d3217..fbf6599 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -1623,7 +1623,13 @@ static int ext3_ordered_writepage(struct page *page,
int err;

J_ASSERT(PageLocked(page));
- WARN_ON_ONCE(IS_RDONLY(inode));
+ /*
+ * We don't want to warn for emergency remount. The condition is
+ * ordered to avoid dereferencing inode->i_sb in non-error case to
+ * avoid slow-downs.
+ */
+ WARN_ON_ONCE(IS_RDONLY(inode) &&
+ !(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS));

/*
* We give up here if we're reentered, because it might be for a
@@ -1698,7 +1704,13 @@ static int ext3_writeback_writepage(struct page *page,
int err;

J_ASSERT(PageLocked(page));
- WARN_ON_ONCE(IS_RDONLY(inode));
+ /*
+ * We don't want to warn for emergency remount. The condition is
+ * ordered to avoid dereferencing inode->i_sb in non-error case to
+ * avoid slow-downs.
+ */
+ WARN_ON_ONCE(IS_RDONLY(inode) &&
+ !(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS));

if (ext3_journal_current_handle())
goto out_fail;
@@ -1741,7 +1753,13 @@ static int ext3_journalled_writepage(struct page *page,
int err;

J_ASSERT(PageLocked(page));
- WARN_ON_ONCE(IS_RDONLY(inode));
+ /*
+ * We don't want to warn for emergency remount. The condition is
+ * ordered to avoid dereferencing inode->i_sb in non-error case to
+ * avoid slow-downs.
+ */
+ WARN_ON_ONCE(IS_RDONLY(inode) &&
+ !(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS));

if (ext3_journal_current_handle())
goto no_write;
--
1.7.1