OpenZFS on Linux and FreeBSD
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Brian Behlendorf 76351672c2 Fix zfsctl_expire_snapshot() deadlock
It is possible for an automounted snapshot which is expiring to
deadlock with a manual unmount of the snapshot.  This can occur
because taskq_cancel_id() will block if the task is currently
executing until it completes.  But it will never complete because
zfsctl_unmount_snapshot() is holding the zsb->z_ctldir_lock which
zfsctl_expire_snapshot() must acquire.

---------------------- z_unmount/0:2153 ---------------------
  mutex_lock                <blocking on zsb->z_ctldir_lock>
  zfsctl_unmount_snapshot
  zfsctl_expire_snapshot
  taskq_thread

------------------------- zfs:10690 -------------------------
  taskq_wait_id             <waiting for z_unmount to exit>
  taskq_cancel_id
  __zfsctl_unmount_snapshot
  zfsctl_unmount_snapshot   <takes zsb->z_ctldir_lock>
  zfs_unmount_snap
  zfs_ioc_destroy_snaps_nvl
  zfsdev_ioctl
  do_vfs_ioctl

We resolve the deadlock by dropping the zsb->z_ctldir_lock before
calling __zfsctl_unmount_snapshot().  The lock is only there to
prevent concurrent modification to the zsb->z_ctldir_snaps AVL
tree.  Moreover, we're careful to remove the zfs_snapentry_t from
the AVL tree before dropping the lock which ensures no other tasks
can find it.  On failure it's added back to the tree.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlap <cdunlap@llnl.gov>
Closes #1527
2013-07-12 10:06:53 -07:00
cmd Add FreeBSD 'zpool labelclear' command 2013-07-09 15:58:05 -07:00
config 3.10 API change: block_device_operations->release() returns void 2013-07-08 15:41:57 -07:00
dracut Refresh dracut module setup 2013-03-21 12:51:06 -07:00
etc Improve OpenRC init script 2013-06-18 17:03:25 -07:00
include Add new kstat for monitoring time in dmu_tx_assign 2013-07-11 13:53:44 -07:00
lib Fix zpool_read_label() 2013-07-09 16:02:04 -07:00
man Add FreeBSD 'zpool labelclear' command 2013-07-09 15:58:05 -07:00
module Fix zfsctl_expire_snapshot() deadlock 2013-07-12 10:06:53 -07:00
patches Adding grub2 mkconfig support patch 2012-07-30 16:17:23 -07:00
rpm Add dkms_version conditional 2013-07-11 15:39:25 -07:00
scripts Open pools asynchronously after module load 2013-07-03 09:24:38 -07:00
udev Open pools asynchronously after module load 2013-07-03 09:24:38 -07:00
.gitignore Ignore *.{deb,rpm,tar.gz} files in the top directory. 2013-04-24 16:18:59 -07:00
AUTHORS Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
COPYRIGHT Refresh links to web site 2013-03-06 15:46:41 -08:00
DISCLAIMER Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
META Tag zfs-0.6.1 2013-03-26 08:50:29 -07:00
Makefile.am build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
OPENSOLARIS.LICENSE Add CDDL license file 2008-12-01 14:49:34 -08:00
README.markdown Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
autogen.sh build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
configure.ac Modified arcstat.py to run on linux 2013-06-18 15:43:15 -07:00
copy-builtin Consistent menuconfig name 2012-08-26 13:49:37 -07:00
zfs-script-config.sh.in Retire zpool_id infrastructure 2013-01-29 12:23:17 -08:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

README.markdown

Native ZFS for Linux!

ZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the Illumos community.

ZFS on Linux, which is also known as ZoL, is currently feature complete. It includes fully functional and stable SPA, DMU, ZVOL, and ZPL layers.

Full documentation for installing ZoL on your favorite Linux distribution can be found at: http://zfsonlinux.org