Hi.
On 24/03/10 02:09, Al Viro wrote:
On Tue, Mar 23, 2010 at 11:03:01AM -0400, Josef Bacik wrote:
sb is an active reference
I don't understand how this is an active reference? We are talking about
s_active right?
It's an opened file, for crying out loud! If there is anything that makes
sure that superblock will stay alive, that is it...
And lose the "locked" argument, please. The sane solution is to make
get_active_super() return it unlocked and have your freeze_bdev() simply
grab s_umount. Unconditionally. I'll do the first part in #untested in
a minute or so (and make it grab s_umount in the current variant of code in
fs/block_dev.c); then your patch would shift taking s_umount down into
freeze_super().
Since TuxOnIce was mentioned, I guess he's thinking on the following
routine.
Regards,
Nigel
/**
* freeze_filesystems - lock all filesystems and force them into a
consistent
* state
* @which: What combination of fuse & non-fuse to freeze.
*/
void freeze_filesystems(int which)
{
struct super_block *sb;
lockdep_off();
/*
* Freeze in reverse order so filesystems dependant upon others are
* frozen in the right order (eg. loopback on ext3).
*/
list_for_each_entry_reverse(sb, &super_blocks, s_list) {
FS_PRINTK(KERN_INFO "Considering %s.%s: (root %p, bdev
%x)",
sb->s_type->name ? sb->s_type->name : "?",
sb->s_subtype ? sb->s_subtype : "", sb->s_root,
sb->s_bdev ? sb->s_bdev->bd_dev : 0);
if (sb->s_type->fs_flags & FS_IS_FUSE &&
sb->s_frozen == SB_UNFROZEN &&
which & FS_FREEZER_FUSE) {
sb->s_frozen = SB_FREEZE_TRANS;
sb->s_flags |= MS_FROZEN;
FS_PRINTK("Fuse filesystem done.\n");
continue;
}
if (!sb->s_root || !sb->s_bdev ||
(sb->s_frozen == SB_FREEZE_TRANS) ||
(sb->s_flags & MS_RDONLY) ||
(sb->s_flags & MS_FROZEN) ||
!(which & FS_FREEZER_NORMAL)) {
FS_PRINTK(KERN_INFO "Nope.\n");
continue;
}
FS_PRINTK(KERN_INFO "Freezing %x... ", sb->s_bdev->bd_dev);
freeze_bdev(sb->s_bdev);
sb->s_flags |= MS_FROZEN;
FS_PRINTK(KERN_INFO "Done.\n");
}
lockdep_on();
}
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