Messages in this thread | | | Date | Wed, 6 May 2009 07:48:27 +0100 | From | Al Viro <> | Subject | Re: [PATCH vfs-2.6:for-next] vfs: remount_fs BKL pushdown |
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On Wed, May 06, 2009 at 02:26:30AM -0400, Christoph Hellwig wrote: > On Wed, May 06, 2009 at 04:51:38AM +0100, Al Viro wrote: > > Actually, I'm not sure that you are right. Especially if we go for your > > "always hold s_umount for sync_filesystem()"; in that case we are guaranteed > > that we'll have an exclusion between ->write_super() and that sucker, so > > there's no reason to push it down into filesystems that do not use lock_super() > > The interesting cases are locking against internal s_lock which at least > extN needs or ->write_super. And I'd really be rather safe than sorry > and audit individual filesystems than introducing bug in an obscure one.
write_super() can *not* get contention against remount. That's the point. And other that write_super, we have very few filesystems that even mention lock_super() anywhere. Yes, ext3 and ext4. Also fat, sysv, ufs and hpfs. That's it. Compare with the number of suckers that have write_super() and especially remount_fs()...
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