ext4: do not try to write superblock on ro remount w/o journal
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>
Cc: stable@vger.kernel.org
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 @@
}
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