Date: Fri, 12 Aug 2016 01:33:31 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Andriy Gapon <avg@FreeBSD.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: Re: svn commit: r303970 - in stable/11/sys/cddl: compat/opensolaris/sys contrib/opensolaris/uts/common/fs/zfs contrib/opensolaris/uts/common/fs/zfs/sys Message-ID: <20160811223331.GF22212@zxy.spb.ru> In-Reply-To: <201608112048.u7BKm4OH076291@repo.freebsd.org> References: <201608112048.u7BKm4OH076291@repo.freebsd.org>
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On Thu, Aug 11, 2016 at 08:48:04PM +0000, Andriy Gapon wrote: > Author: avg > Date: Thu Aug 11 20:48:03 2016 > New Revision: 303970 > URL: https://svnweb.freebsd.org/changeset/base/303970 > > Log: > MFC r303763,303791,303869: zfs: honour and make use of vfs vnode locking protocol > > ZFS POSIX Layer is originally written for Solaris VFS which is very > different from FreeBSD VFS. Most importantly many things that FreeBSD VFS > manages on behalf of all filesystems are implemented in ZPL in a different > way. > Thus, ZPL contains code that is redundant on FreeBSD or duplicates VFS > functionality or, in the worst cases, badly interacts / interferes > with VFS. > > The most prominent problem is a deadlock caused by the lock order reversal > of vnode locks that may happen with concurrent zfs_rename() and lookup(). > The deadlock is a result of zfs_rename() not observing the vnode locking > contract expected by VFS. > > This commit removes all ZPL internal locking that protects parent-child > relationships of filesystem nodes. These relationships are protected > by vnode locks and the code is changed to take advantage of that fact > and to properly interact with VFS. > > Removal of the internal locking allowed all ZPL dmu_tx_assign calls to > use TXG_WAIT mode. > > Another victim, disputable perhaps, is ZFS support for filesystems with > mixed case sensitivity. That support is not provided by the OS anyway, > so in ZFS it was a buch of dead code. > > To do: > - replace ZFS_ENTER mechanism with VFS managed / visible mechanism > - replace zfs_zget with zfs_vget[f] as much as possible > - get rid of not really useful now zfs_freebsd_* adapters > - more cleanups of unneeded / unused code > - fix / replace .zfs support MFC to 10.x/9.x planed?
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