On Fri, Aug 12, 2016 at 02:20:25AM +0300, Slawa Olhovchenkov wrote: > On Thu, Aug 11, 2016 at 11:13:17PM +0000, Glen Barber wrote: > > > On Fri, Aug 12, 2016 at 02:07:47AM +0300, Slawa Olhovchenkov wrote: > > > On Thu, Aug 11, 2016 at 10:57:23PM +0000, Glen Barber wrote: > > > > > > > On Fri, Aug 12, 2016 at 01:52:02AM +0300, Slawa Olhovchenkov wrote: > > > > > On Thu, Aug 11, 2016 at 10:36:37PM +0000, Glen Barber wrote: > > > > > > > > > > > On Fri, Aug 12, 2016 at 01:33:31AM +0300, Slawa Olhovchenkov wrote: > > > > > > > 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? > > > > > > > > > > > > > > > > > > > As I understand it, this does not affect stable/10. > > > > > > > > > > Sure? > > > > > I think ZFS/VFS layers don't change between 9.x and 11.x > > > > > > > > > > > > > No, but as I understand it, a commit to head tickled this bug. avg@ can > > > > correct me if I am wrong. > > > > > > May be I am wrong, I see messages about like issuses in 9.x/10.x. > > > As I understund this is more clear implementation. > > > Also, unification in 12.x/10.x take benefit for MFC other ZFS diffs. > > > > > > > I agree with you. I am just unsure if this particular bug affects 10.x > > and 9.x. > > What purpose to limit (?) MFC to 9.x/10.x to bug fix only? > Or I am missing some in ypu point? >
I think you are missing what I mean. I am not sure if the change that introduced this issue made it to 10.x or 9.x. But, I know it is a long lasting issue that was around for a while, but the change in current that triggered this specific issue does not affect 10.x or 9.x. Glen
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