On Fri, Aug 05, 2016 at 06:23:06AM +0000, Andriy Gapon wrote: > Author: avg > Date: Fri Aug 5 06:23:06 2016 > New Revision: 303763 > URL: https://svnweb.freebsd.org/changeset/base/303763 > > Log: > 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 > > PR: 209158 > Reported by: many > Tested by: many (thank you all!) > MFC after: 5 days > Sponsored by: HybridCluster / ClusterHQ > Differential Revision: https://reviews.freebsd.org/D6533 >
Thank you very much for working on this. Glen
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