On Tue 02-03-10 17:04:26, Dmitry Monakhov wrote:
> Jan Kara <jack@xxxxxxx> writes:
>
> > On Sat 27-02-10 03:25:49, Dmitry Monakhov wrote:
> >> +/**
> >> + * Check whenever is it possible to remount given sb to readonly.
> >> + * @sb : super block in question
> >> + *
> >> + * Caller is responsible to set ST_REMOUNT_RO state before the call.
> >> + */
> >> +int fs_may_remount_ro(struct super_block *sb)
> >> +{
> >> + struct vfsmount *mnt;
> >> + int ret = 1;
> >> + spin_lock(&vfsmount_lock);
> >> + list_for_each_entry(mnt, &sb->s_vfsmount, mnt_sb_list) {
> >> + ret = !mnt_check_writers(mnt, 0);
> >> + if (ret)
> >> + break;
> >> + }
> >> + spin_unlock(&vfsmount_lock);
> >> + /*
> >> + * If new writer appears after we have checked all vfsmounts.
> >> + * Then ST_REMOUNT_RO bit will be cleared.
> >> + */
> >> + if (!test_bit(ST_REMOUNT_RO, &sb->s_state))
> >> + ret = 0;
> >> + return ret;
> >> +}
> > This misses the case when the superblock as unlinked-but-open files.
> > In such case we have to fail remount RO as well. The original
> > fs_may_remount_ro checks for that..
> Since file is opened for write one of vfsmnt struct would have non
> zero write count. So -EBUSY will be returned from fs_may_remount_ro()
But file can be open for reading only...
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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