mirror_zfs/module
Brian Behlendorf 3982d959c5 Linux 5.3 compat: retire rw_tryupgrade()
The Linux kernel's rwsem's have never provided an interface to
allow a reader to be upgraded to a writer.  Historically, this
functionality has been implemented by a SPL wrapper function.
However, this approach depends on internal knowledge of the
rw_semaphore and is therefore rather brittle.

Since the ZFS code must always be able to fallback to rw_exit()
and rw_enter() when an rw_tryupgrade() fails; this functionality
isn't critical.  Furthermore, the only potentially performance
sensitive consumer is dmu_zfetch() and no decrease in performance
was observed with this change applied.  See the PR comments for
additional testing details.

Therefore, it is being retired to make the build more robust and
to simplify the rwlock implementation.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #9029
2019-09-25 11:27:49 -07:00
..
avl Update build system and packaging 2018-05-29 16:00:33 -07:00
icp Minor style cleanup 2019-09-25 11:27:49 -07:00
lua Update build system and packaging 2018-05-29 16:00:33 -07:00
nvpair Use NV_ENCODE_NATIVE for nvlist encoding variable 2019-04-26 11:24:31 -07:00
spl Linux 5.3 compat: retire rw_tryupgrade() 2019-09-25 11:27:49 -07:00
unicode Update build system and packaging 2018-05-29 16:00:33 -07:00
zcommon Minor style cleanup 2019-09-25 11:27:49 -07:00
zfs Fix lockdep recursive locking false positive in dbuf_destroy 2019-09-25 11:27:49 -07:00
.gitignore Prepare SPL repo to merge with ZFS repo 2018-05-29 14:51:39 -07:00
Makefile.in Fix out-of-tree build failures 2019-09-25 11:27:48 -07:00