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Jitendra Patidar 361a7e8211
log xattr=sa create/remove/update to ZIL
As such, there are no specific synchronous semantics defined for
the xattrs. But for xattr=on, it does log to ZIL and zil_commit() is
done, if sync=always is set on dataset. This provides sync semantics
for xattr=on with sync=always set on dataset.

For the xattr=sa implementation, it doesn't log to ZIL, so, even with
sync=always, xattrs are not guaranteed to be synced before xattr call
returns to caller. So, xattr can be lost if system crash happens, before
txg carrying xattr transaction is synced.

This change adds xattr=sa logging to ZIL on xattr create/remove/update
and xattrs are synced to ZIL (zil_commit() done) for sync=always.
This makes xattr=sa behavior similar to xattr=on.

Implementation notes:
The actual logging is fairly straight-forward and does not warrant
additional explanation.
However, it has been 14 years since we last added new TX types
to the ZIL [1], hence this is the first time we do it after the
introduction of zpool features. Therefore, here is an overview of the
feature activation and deactivation workflow:

1. The feature must be enabled. Otherwise, we don't log the new
    record type. This ensures compatibility with older software.
2. The feature is activated per-dataset, since the ZIL is per-dataset.
3. If the feature is enabled and dataset is not for zvol, any append to
    the ZIL chain will activate the feature for the dataset. Likewise
    for starting a new ZIL chain.
4. A dataset that doesn't have a ZIL chain has the feature deactivated.

We ensure (3) by activating on the first zil_commit() after the feature
was enabled. Since activating the features requires waiting for txg
sync, the first zil_commit() after enabling the feature will be slower
than usual. The downside is that this is really a conservative
approximation: even if we never append a 'TX_SETSAXATTR' to the ZIL
chain, we pay the penalty for feature activation. The upside is that the
user is in control of when we pay the penalty, i.e., upon enabling the
feature.

We ensure (4) by hooking into zil_sync(), where ZIL destroy actually
happens.

One more piece on feature activation, since it's spread across
multiple functions:

zil_commit()
  zil_process_commit_list()
    if lwb == NULL // first zil_commit since zil_open
      zil_create()
        if no log block pointer in ZIL header:
          if feature enabled and not active:
	    // CASE 1
            enable, COALESCE txg wait with dmu_tx that allocated the
	    log block
         else // log block was allocated earlier than this zil_open
          if feature enabled and not active:
	    // CASE 2
            enable, EXPLICIT txg wait
    else // already have an in-DRAM LWB
      if feature enabled and not active:
        // this happens when we enable the feature after zil_create
	// CASE 3
        enable, EXPLICIT txg wait

[1] da6c28aaf6

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Christian Schwarz <christian.schwarz@nutanix.com>
Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Reviewed-by: Ryan Moeller <freqlabs@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jitendra Patidar <jitendra.patidar@nutanix.com>
Closes #8768 
Closes #9078
2022-02-22 13:06:43 -08:00
.github Colorize the Github test output 2022-02-16 11:40:25 -08:00
cmd log xattr=sa create/remove/update to ZIL 2022-02-22 13:06:43 -08:00
config config: add -Wextra (sans sign-compare and missing-field-initializers) 2022-02-18 09:35:02 -08:00
contrib userspace: mark arguments used 2022-02-18 09:34:08 -08:00
etc systemd: read initconfdir 2022-02-22 12:59:11 -08:00
include log xattr=sa create/remove/update to ZIL 2022-02-22 13:06:43 -08:00
lib log xattr=sa create/remove/update to ZIL 2022-02-22 13:06:43 -08:00
man log xattr=sa create/remove/update to ZIL 2022-02-22 13:06:43 -08:00
module log xattr=sa create/remove/update to ZIL 2022-02-22 13:06:43 -08:00
rpm contrib: rename initrd READMEs to README.md 2022-02-11 11:44:27 -08:00
scripts cstyle: forbid ARGSUSED 2022-02-18 09:35:06 -08:00
tests log xattr=sa create/remove/update to ZIL 2022-02-22 13:06:43 -08:00
udev Udev rules: remove zvol compat symlinks (without the leading zvol/) 2021-07-06 13:41:17 -07:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore Add FreeBSD support to OpenZFS 2020-04-14 11:36:28 -07:00
.gitmodules .gitmodules: link to openzfs github repository 2021-04-12 09:37:23 -07:00
AUTHORS Add zstd support to zfs 2020-08-20 10:30:06 -07:00
autogen.sh Cause autogen.sh to fail if autoreconf fails 2018-07-06 09:27:37 -07:00
CODE_OF_CONDUCT.md Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
configure.ac Linux 5.16 compat: don't use XSTATE_XSAVE to save FPU state 2022-02-09 12:50:10 -08:00
copy-builtin copy-builtin: posix conformance 2021-05-08 08:58:26 -07:00
COPYRIGHT Fix typos 2020-06-09 21:24:09 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am checkabi/storeabi relevant only to x86_64 2022-02-16 11:48:01 -08:00
META Linux 5.15 compat: META (#12824) 2021-12-07 15:35:42 -08:00
NEWS Fix NEWS file 2020-08-26 21:44:41 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md README: Update OpenZFS website url 2022-01-06 16:25:01 -08:00
RELEASES.md Add RELEASES.md file 2021-04-02 16:33:40 -07:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are any supported branches and releases starting from 12.2-RELEASE.