linux-kernel - [17/42] ext3: Dont warn from writepage when readonly inode is spotted after error

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Date:	Tue, 10 Jan 2012 13:48:27 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Jan Kara <jack@...e.cz>
Subject: [17/42] ext3: Dont warn from writepage when readonly inode is spotted after error

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@...e.cz>

commit 33c104d415e92a51aaf638dc3d93920cfa601e5c upstream.

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.

Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/ext3/inode.c |   24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -1617,7 +1617,13 @@ static int ext3_ordered_writepage(struct
 	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
@@ -1692,7 +1698,13 @@ static int ext3_writeback_writepage(stru
 	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;
@@ -1735,7 +1747,13 @@ static int ext3_journalled_writepage(str
 	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;


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