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()
>
> Honza
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