From c41303ced67c4ebf51bf2e7d0f139155e09e0939 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Maciej=20=C5=BBenczykowski?= Date: Wed, 27 Oct 2010 21:30:06 -0400 Subject: [PATCH] ext4: don't update sb journal_devnum when RO dev MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit An ext4 filesystem on a read-only device, with an external journal which is at a different device number then recorded in the superblock will fail to honor the read-only setting of the device and trigger a superblock update (write). For example: - ext4 on a software raid which is in read-only mode - external journal on a read-write device which has changed device num - attempt to mount with -o journal_dev= - hits BUG_ON(mddev->ro = 1) in md.c Cc: Theodore Ts'o Signed-off-by: Maciej Żenczykowski Signed-off-by: "Theodore Ts'o" --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c5b890140d01..8a24e9be7cb0 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3908,7 +3908,7 @@ static int ext4_load_journal(struct super_block *sb, EXT4_SB(sb)->s_journal = journal; ext4_clear_journal_err(sb, es); - if (journal_devnum && + if (!really_read_only && journal_devnum && journal_devnum != le32_to_cpu(es->s_journal_dev)) { es->s_journal_dev = cpu_to_le32(journal_devnum); -- 2.20.1