| From: Michael Tokarev <mjt@tls.msk.ru> |
| Date: Tue, 25 Dec 2012 14:08:16 -0500 |
| Subject: 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 <mjt@tls.msk.ru> |
| Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| 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 4969167..183ae34 100644 |
| --- a/fs/ext4/super.c |
| +++ b/fs/ext4/super.c |
| @@ -4729,7 +4729,7 @@ 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 |
