ZFS v15 slowness

[Martin Matuska]

 Hi Pawel and Xin,

I have a user report and I can confirm myself of ZFS v15 acting slower
than before the import on several systems.
I would therefore like to propose the combined stat() and rrwlock
speedup patch as this has noticeable impact on this issue in my tests
and the overall impression of system responsiveness.

http://mfsbsd.vx.sk/zfs/head-9981-10143-10232-10250-10269.patch

The patch code remained in OpenSolaris like that until today and it was
part of the original zfs v16 patch I posted so it has already been
tested by the users.
A small part of the 10143 patch is not imported, see notes below. The
patch covers the following opensolaris revisions and bug IDs:

9981:b4907297e740
-----------------
stat() performance on files on zfs should be improved
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6775100

rrwlock is overly protective of its counters
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6827779

10143:d2d432dfe597 (small part not included, see below)
-----------------
memory leaks found at: zfs_acl_alloc/zfs_acl_node_alloc
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6857433

truncate() on zfsroot succeeds when file has a component of its path set
without access permission
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6860318

10232:f37b85f7e03e
-----------------
zfs sometimes incorrectly giving search access to a dir
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6865875

10250:b179ceb34b62
-----------------
zpool_upgrade_007_pos testcase panic'd with BAD TRAP: type=e (#pf Page
fault)
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6867395

10269:2788675568fd
-----------------
zfs_rezget() can be hazardous when znode has a cached ACL
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6868276

----------------------------------

If the import of a small part of 10143
(http://mfsbsd.vx.sk/zfs/head-10143-addon.patch) is possible only after
importing ABE:
http://mfsbsd.vx.sk/zfs/head-9749-9866.patch

9749:105f407a2680
-----------------
Support for Access Based Enumeration
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6802734

A test driver for some ZFS features would be beneficial (this is the yet
unused zlook program)
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6826760

inconsistent xattr readdir behavior with too-small buffer
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6844861

9866:ddc5f1d8eb4e
-----------------
zfs with rstchown=0 or file_chown_self privilege allows user to "take"
ownership
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6848431