| From | Greg Kroah-Hartman <> | Subject | [ 35/71] ext4: do not try to write superblock on ro remount w/o journal | Date | Tue, 15 Jan 2013 14:54:32 -0800 |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Michael Tokarev <mjt@tls.msk.ru>
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4438,7 +4438,7 @@ static int ext4_remount(struct super_blo } 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
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