On Mon, 02 Feb 2009 16:55:18 -0600
Eric Sandeen <sandeen@xxxxxxxxxx> wrote:
> (this version fixes a couple small issues raised by Randy Dunlap)
> (and adds sb_lock locking I forgot, as akpm pointed out)
> (Randy's CONFIG_BLOCK fix should still apply over this)
<converts it to a delta so I can see what you did>
--- a/fs/buffer.c~allow-sysrq-emergency-thaw-to-thaw-frozen-filesystems-v4
+++ a/fs/buffer.c
@@ -263,11 +263,13 @@ void do_thaw_all(unsigned long unused)
struct super_block *sb;
char b[BDEVNAME_SIZE];
+ spin_lock(&sb_lock);
list_for_each_entry(sb, &super_blocks, s_list) {
while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
printk(KERN_WARNING "Emergency Thaw on %s\n",
bdevname(sb->s_bdev, b));
}
+ spin_unlock(&sb_lock);
printk(KERN_WARNING "Emergency Thaw complete\n");
}
_
Can't call thaw_bdev() under spinlock.
If we're going to do this, I think it will need the whole
sb_lock/s_count/s_umount song-n-dance.
It's a pretty common operation. What you want is, I think, identical
to sync_supers(), only with one line changed.
so we could do
void apply_to_all_supers(void (fn)(struct super_block *))
{
struct super_block *sb;
spin_lock(&sb_lock);
restart:
list_for_each_entry(sb, &super_blocks, s_list) {
if (sb->s_dirt) {
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
(*fn)(sb);
up_read(&sb->s_umount);
spin_lock(&sb_lock);
if (__put_super_and_need_restart(sb))
goto restart;
}
}
spin_unlock(&sb_lock);
}
That isn't quite sufficient to use for get_super(), but I think it
could be made so.
Ditto user_get_super().
Ditto do_emergency_remount()
But that's a separate little project for someone. For the purposes of
this patch I guess you could do yet another copy-n-paste.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
