Illumos 3464

[dweeezil]

Notes from the Illumos commit:

Description

The locking code around dsl_datasets and dsl_dir's is responsible for several deadlocks
and race conditions, most prominently:

a concurrent "zfs list" while running "zfs destroy" can cause the destroy to fail
with EBUSY. bug #3041 deadlock between dp->dp_config_rwlock and
ds->ds_opening_lock

To fix this, we must restructure the locking, and change the interface to synctasks.

The wad that will fix this also addresses the following:

improve performance of "zfs recv" by reducing the number of calls to txg_wait_synced()
fix zfs refquota can be violated by "zfs rollback" and "zfs receive" operations
fix ztest fails in ztest_dmu_snapshot_hold due to bad printf string
remove unused zc_top_ds from zfs_cmd_t
fix zdb crashes on pools < SPA_VERSION_DEADLISTS
remove undocumented "zfs hold -t" flag (for temporary hold)
use ASSERT0 / VERIFY0 in more places
new libzfs_core routines: lzc_hold(), lzc_release(), lzc_get_holds() (for user holds)
move some routines from dsl_dataset.c to dsl_destroy.c, dsl_userhold.c
make rrwlock.c work in userland (libzpool.so)
change all synctask consumers to new model
remove ds_recvlock; all receives use "%recv" child to prevent concurrent receives
"zfs destroy" destroys multiple snapshots at once, so it is much faster

This patch is based on the pull request #1496 which is based on master as of a day ago or so.

[dweeezil]

Pushed dweeezil/zfs@4a39697 to rebase to dweeezil/zfs@1826f91 of #1496.

[dweeezil]

Pushed dweeezil/zfs@f1632c7 to rebase to dweeezil/zfs@ac02a59 and, therefore, current zfsonlinux/zfs master (0.6.2).

[dweeezil]

Pushed dweeezil/zfs@6d3a0c7 to fix a long-standing porting issue in which zvol minors were re-created prior to a rename rather than after a rename. This is, of course, still based on dweeezil/zfs@ac02a59 which is, itself, based on zfsonlinux/zfs master as of 0.6.2.

[behlendorf]

@dweeezil I ran in to some minor build issues with the patch when building pacakges. Please include the new headers in include/sys/Makefile.am so make dist includes them in the tarball. Like this:

diff --git a/include/sys/Makefile.am b/include/sys/Makefile.am
index 2245ff4..008a3ac 100644
--- a/include/sys/Makefile.am
+++ b/include/sys/Makefile.am
@@ -13,17 +13,20 @@ COMMON_H = \
        $(top_srcdir)/include/sys/dmu_impl.h \
        $(top_srcdir)/include/sys/dmu_objset.h \
        $(top_srcdir)/include/sys/dmu_traverse.h \
+       $(top_srcdir)/include/sys/dmu_send.h \
        $(top_srcdir)/include/sys/dmu_tx.h \
        $(top_srcdir)/include/sys/dmu_zfetch.h \
        $(top_srcdir)/include/sys/dnode.h \
        $(top_srcdir)/include/sys/dsl_dataset.h \
        $(top_srcdir)/include/sys/dsl_deadlist.h \
        $(top_srcdir)/include/sys/dsl_deleg.h \
+       $(top_srcdir)/include/sys/dsl_destroy.h \
        $(top_srcdir)/include/sys/dsl_dir.h \
        $(top_srcdir)/include/sys/dsl_pool.h \
        $(top_srcdir)/include/sys/dsl_prop.h \
        $(top_srcdir)/include/sys/dsl_scan.h \
        $(top_srcdir)/include/sys/dsl_synctask.h \
+       $(top_srcdir)/include/sys/dsl_userhold.h \
        $(top_srcdir)/include/sys/efi_partition.h \
        $(top_srcdir)/include/sys/metaslab.h \
        $(top_srcdir)/include/sys/metaslab_impl.h \

[dweeezil]

@behlendorf I just pushed dweeezil/zfs@4789bce which adds the missing headers to include/sys/Makefile.am and also re-alphabetizes the list by re-generating it from scratch.

[behlendorf]

Merged. The patch passed all of the automated testing and it's been in Illumos for some time. However since it so large I expect that we missed something so let's keep an eye out for new regressions. @dweeezil thank you again for doing this it was a huge amount of work and I appreciate it greatly!

13fe019 Illumos #3464