Ping? Almost 2 months has passed since initial patch... Thanks, /mjt On 25.10.2012 12:39, Michael Tokarev wrote: > 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. > > The proposed fix tests whenever both old mount flags and new mount > flags does not include MS_READONLY, and only in this case calls > ext4_commit_super(). > > Maybe it is sufficient to check for MS_READONLY just in old mount > options (old_sb_flags). Note this is journal-less mode, so, for > example, we weren't have journal replay operation, so if old flags > include MS_REASONLY, we shuold have no dirty blocks at all, and > there's no reason to call ext4_commit_super(). > > But only in case both old and new flags include MS_READONLY we're > certain we will not write anything - if new flag does not include > this bit, we will write sooner or later anyway, so preventing just > one commit_super() at the _beginning_ of mount is not really necessary. > > This change probably applicable to -stable, -- not because it fixes > a serious bug, but because the messages printed by the kernel are > rather scary for an average user. On the other hand, actual usage > of ext4 in nojournal mode on a read-only medium is very rare. > > Thanks to Eric Sandeen for help in diagnosing this issue. > > Signed-off-By: Michael Tokarev <mjt@xxxxxxxxxx> > --- > 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 3e0851e..2e896fd 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -4687,7 +4687,7 @@ 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 && !(sb->s_flags & old_sb_flags & MS_RDONLY)) > ext4_commit_super(sb, 1); > > unlock_super(sb); -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
