Re: ext3 updates for 2.4.20

Chris Mason (mason@suse.com)
16 Dec 2002 16:28:12 -0500


Hmmm, this took me a while to find the first time around in the
commit_super code, and I almost forgot about it.

Looking at the loop in sync_supers()

while (sb != sb_entry(&super_blocks))
if (sb->s_dirt) {
sb->s_count++;
spin_unlock(&sb_lock);

Right here, we can race against kill_super, which means an unmount can
make the FS go away completely. The only thing that saves the
write_super() call is a check for s->s_root != NULL. Since we don't
check that before calling sync_fs, it should race against an unmount.

down_read(&sb->s_umount);
write_super(sb);
if (wait && sb->s_op && sb->s_op->sync_fs)
sb->s_op->sync_fs(sb);
drop_super(sb);
goto restart;
} else

Any reason ext3 can't have a check for s_root in there?

-chris

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