From ad74aa67b8cf06b159cf72b08efe42533db49685 Mon Sep 17 00:00:00 2001 From: Michael Tokarev Date: Tue, 25 Dec 2012 14:08:16 -0500 Subject: [PATCH] ext4: do not try to write superblock on ro remount w/o journal commit d096ad0f79a782935d2e06ae8fb235e8c5397775 upstream. When a journal-less ext4 filesystem is mounted on a read-only block device (blockdev --setro will do), each remount (for other, unrelated, flags, like suid=>nosuid etc) results in a series of scary messages from kernel telling about I/O errors on the device. This is becauese of the following code ext4_remount(): if (sbi->s_journal == NULL) ext4_commit_super(sb, 1); at the end of remount procedure, which forces writing (flushing) of a superblock regardless whenever it is dirty or not, if the filesystem is readonly or not, and whenever the device itself is readonly or not. We only need call ext4_commit_super when the file system had been previously mounted read/write. Thanks to Eric Sandeen for help in diagnosing this issue. Signed-off-By: Michael Tokarev Signed-off-by: "Theodore Ts'o" Signed-off-by: Ben Hutchings --- 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 4e03de4da83f..24ac7a293490 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4654,7 +4654,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data) } ext4_setup_system_zone(sb); - if (sbi->s_journal == NULL) + if (sbi->s_journal == NULL && !(old_sb_flags & MS_RDONLY)) ext4_commit_super(sb, 1); #ifdef CONFIG_QUOTA -- 2.39.2