linux-kernel - [PATCH 4/4] ext3: Warn if mounting rw on a disk requiring stable page writes

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Message-ID: <20121121020056.10225.15220.stgit@blackbox.djwong.org>
Date:	Tue, 20 Nov 2012 18:00:56 -0800
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	axboe@...nel.dk, lucho@...kov.net, jack@...e.cz, ericvh@...il.com,
	tytso@....edu, rminnich@...dia.gov, viro@...iv.linux.org.uk
Cc:	martin.petersen@...cle.com, neilb@...e.de, david@...morbit.com,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	adilger.kernel@...ger.ca, bharrosh@...asas.com, jlayton@...ba.org,
	v9fs-developer@...ts.sourceforge.net, linux-ext4@...r.kernel.org
Subject: [PATCH 4/4] ext3: Warn if mounting rw on a disk requiring stable page
 writes

ext3 doesn't properly isolate pages from changes during writeback.  Since the
recommended fix is to use ext4, for now we'll just print a warning if the user
tries to mount in write mode.

Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
 fs/ext3/super.c |    8 ++++++++
 1 file changed, 8 insertions(+)


diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 5366393..5b3725d 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -1325,6 +1325,14 @@ static int ext3_setup_super(struct super_block *sb, struct ext3_super_block *es,
 			"forcing read-only mode");
 		res = MS_RDONLY;
 	}
+	if (!read_only &&
+	    queue_requires_stable_pages(bdev_get_queue(sb->s_bdev))) {
+		ext3_msg(sb, KERN_ERR,
+			"error: ext3 cannot safely write data to a disk "
+			"requiring stable pages writes; forcing read-only "
+			"mode.  Upgrading to ext4 is recommended.");
+		res = MS_RDONLY;
+	}
 	if (read_only)
 		return res;
 	if (!(sbi->s_mount_state & EXT3_VALID_FS))

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