mirror_zfs/module
Brian Behlendorf 751941e248 Fix dnode allocation race
When performing concurrent object allocations using the new
multi-threaded allocator and large dnodes it's possible to
allocate overlapping large dnodes.

This case should have been handled by detecting an error
returned by dnode_hold_impl().  But that logic only checked
the returned dnp was not-NULL, and the dnp variable was not
reset to NULL when retrying.  Resolve this issue by properly
checking the return value of dnode_hold_impl().

Additionally, it was possible that dnode_hold_impl() would
misreport a dnode as free when it was in fact in use.  This
could occurs for two reasons:

* The per-slot zrl_lock must be held over the entire critical
  section which includes the alloc/free until the new dnode
  is assigned to children_dnodes.  Additionally, all of the
  zrl_lock's in the range must be held to protect moving
  dnodes.

* The dn->dn_ot_type cannot be solely relied upon to check
  the type.  When allocating a new dnode its type will be
  DMU_OT_NONE after dnode_create().  Only latter when
  dnode_allocate() is called will it transition to the new
  type.  This means there's a window when allocating where
  it can mistaken for a free dnode.

Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Ned Bass <bass6@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #6414
Closes #6439
2017-08-08 10:17:33 -07:00
..
avl Fix uninitialized variable in avl_add() 2016-07-25 14:21:34 -07:00
icp Clang fixes 2017-07-05 10:38:20 -07:00
nvpair OpenZFS 7812 - Remove gender specific language 2017-02-24 11:07:04 -08:00
unicode codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
zcommon Fix buffer overflow in dsl_dataset_name() 2017-07-24 12:56:49 -07:00
zfs Fix dnode allocation race 2017-08-08 10:17:33 -07:00
zpios codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
.gitignore Improve gitignore 2017-05-25 10:14:13 -07:00
Makefile.in GZIP compression offloading with QAT accelerator 2017-03-22 17:58:47 -07:00