Commit Graph

980 Commits

Author SHA1 Message Date
Brian Behlendorf
a3000f9358 Revert "dmu_objset_userquota_get_ids uses dn_bonus unsafely"
This reverts commit 5f8e1e8505.  It
was determined that this patch introduced the quota regression
described in #3789.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3443
Issue #3789
2015-09-25 12:50:24 -07:00
Brian Behlendorf
5592404784 Fix synchronous behavior in __vdev_disk_physio()
Commit b39c22b set the READ_SYNC and WRITE_SYNC flags for a bio
based on the ZIO_PRIORITY_* flag passed in.  This had the unnoticed
side-effect of making the vdev_disk_io_start() synchronous for
certain I/Os.

This in turn resulted in vdev_disk_io_start() being able to
re-dispatch zio's which would result in a RCU stalls when a disk
was removed from the system.  Additionally, this could negatively
impact performance and explains the performance regressions reported
in both #3829 and #3780.

This patch resolves the issue by making the blocking behavior
dependent on a 'wait' flag being passed rather than overloading
the passed bio flags.

Finally, the WRITE_SYNC and READ_SYNC behavior is restricted to
non-rotational devices where there is no benefit to queuing to
aggregate the I/O.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3652
Issue #3780
Issue #3785
Issue #3817
Issue #3821
Issue #3829
Issue #3832
Issue #3870
2015-09-25 12:47:31 -07:00
Brian Behlendorf
ef5b2e1048 Avoid blocking in arc_reclaim_thread()
As described in the comment above arc_reclaim_thread() it's critical
that the reclaim thread be careful about blocking.  Just like it must
never wait on a hash lock, it must never wait on a task which can in
turn wait on the CV in arc_get_data_buf().  This will deadlock, see
issue #3822 for full backtraces showing the problem.

To resolve this issue arc_kmem_reap_now() has been updated to use the
asynchronous arc prune function.  This means that arc_prune_async()
may now be called while there are still outstanding arc_prune_tasks.
However, this isn't a problem because arc_prune_async() already
keeps a reference count preventing multiple outstanding tasks per
registered consumer.  Functionally, this behavior is the same as
the counterpart illumos function dnlc_reduce_cache().

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue #3808
Issue #3834
Issue #3822
2015-09-25 12:45:47 -07:00
Brian Behlendorf
04870568e6 Disable zpl_nr_cached_objects() callback
The zpl_nr_cached_objects() function has been disabled because in the
current code it doesn't provide any critical functionality and it may
result in a deadlock under certain circumstances.  However, because
we expect to need these hooks in the future this code has not been
entirely removed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3719
2015-09-25 12:45:42 -07:00
Brian Behlendorf
d4787d55ad Allow NFS activity to defer snapshot unmounts
Accessing a snapshot via NFS should cause an auto-unmount of that
snapshot to be deferred until such as time as the snapshot is idle.
This is analogous to the zpl_revalidate logic employed by locally
mounted snapshots.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3794
2015-09-25 12:45:38 -07:00
Lukas Wunner
784a7fe5d9 Linux 4.3 compat: bio_end_io_t / BIO_UPTODATE
Commit torvalds/linux@4246a0b63b
("block: add a bi_error field to struct bio") dropped the error
argument from bio_endio in favor of newly introduced bio->bi_error.
This also replaces bio->bi_flags value BIO_UPTODATE.

bio_endio was a 3 argument function until Linux 2.6.24, which made it
a 2 argument function, and now the prototype has changed yet again to
a 1 argument function. Support for pre 2.6.24 kernels was already
dropped with 37f9dac592 ("zvol processing should use struct bio")
which assumed the 2 argument version in zvol_request(). Remaining code
to support the 3 argument version is hereby removed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Issue #3799
2015-09-25 12:44:54 -07:00
Ned Bass
3af56fd95f Honor xattr=sa dataset property
ZFS incorrectly uses directory-based extended attributes even when
xattr=sa is specified as a dataset property or mount option. Support to
honor temporary mount options including "xattr" was added in commit
0282c4137e. There are two issues with the
mount option handling:

* Libzfs has historically included "xattr" in its list of default mount
  options. This overrides the dataset property, so the dataset is always
  configured to use directory-based xattrs even when the xattr dataset
  property is set to off or sa. Address this by removing "xattr" from
  the set of default mount options in libzfs.

* There was no way to enable system attribute-based extended attributes
  using temporary mount options. Add the mount options "saxattr" and
  "dirxattr" which enable the xattr behavior their names suggest.  This
  approach has the advantages of mirroring the valid xattr dataset
  property values and following existing conventions for mount option
  names.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3787
2015-09-19 14:04:14 -07:00
Brian Behlendorf
66aad10ce8 Fix NULL as mount(2) syscall data parameter
Passing NULL for the mount data should not result in EINVAL.  It
should be treated as if an empty string were passed and succeed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #3771
2015-09-19 14:03:01 -07:00
Richard Yao
f52ebcb3eb Discard on zvols should not exceed the length of a block
37f9dac592 replaced the end-start
calculation with a cached value, but neglected to update it on discard
operations. This can cause us to discard data not requested, causing
data loss on zvols.

Reported-by: Richard Connon <richard.connon@zynstra.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3798
2015-09-19 14:00:14 -07:00
Arne Jansen
4e0f33ffe0 Illumos 6214 - zpools going south
6214 zpools going south
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>

References:
  https://www.illumos.org/issues/6214
  http://cr.illumos.org/~webrev/sensille/6214_zpools_going_south/

Porting Notes:

Reintroduce b_compress to the l2arc_buf_hdr_t.  In commit b9541d6
the compression flags were moved to the generic b_flags in the
arc_buf_hdr_t.  This is a problem because l2arc_compress_buf()
may manipulate the compression flags and this can only be done
safely under the hash lock which is not held.  See Illumos 6214
for a detailed analysis of the race.

HDR_GET_COMPRESS() macro was removed from arc_buf_info().

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3757
2015-09-11 11:14:38 -07:00
Brian Behlendorf
9965059ab9 Prefetch start and end of volumes
When adding a zvol to the system prefetch zvol_prefetch_bytes from the
start and end of the volume.  Prefetching these regions of the volume is
desirable because they are likely to be accessed immediately by blkid(8),
the kernel scanning for a partition table, or another task which probes
the devices.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3659
2015-09-09 14:38:29 -07:00
Richard Yao
8198d18ca7 Reintroduce IO accounting on zvols on Linux 3.19+
zfsonlinux/zfs@e20cd6f7a8 caused us to
lose IO accounting on zvols. When I originally wrote that last year, the
symbols we needed to maintain IO accounting were GPL exported, but
torvalds/linux@394ffa503b provided
suitable symbols for restoring this functionality 4 months later.  We
can call them to restore the IO accounting on Linux 3.19 and later as
well as any older kernels where that patch is backported.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3741
2015-09-09 09:29:24 -07:00
Brian Behlendorf
3b36f8319d Add dbgmsg kstat
Internally ZFS keeps a small log to facilitate debugging.  By default
the log is disabled, to enable it set zfs_dbgmsg_enable=1.  The contents
of the log can be accessed by reading the /proc/spl/kstat/zfs/dbgmsg file.
Writing 0 to this proc file clears the log.

$ echo 1 >/sys/module/zfs/parameters/zfs_dbgmsg_enable
$ echo 0 >/proc/spl/kstat/zfs/dbgmsg
$ zpool import tank
$ cat /proc/spl/kstat/zfs/dbgmsg
1 0 0x01 -1 0 2492357525542 2525836565501
timestamp    message
1441141408   spa=tank async request task=1
1441141408   txg 70 open pool version 5000; software version 5000/5; ...
1441141409   spa=tank async request task=32
1441141409   txg 72 import pool version 5000; software version 5000/5; ...
1441141414   command: lt-zpool import tank

Note the zfs_dbgmsg() and dprintf() functions are both now mapped to
the same log.  As mentioned above the kernel debug log can be accessed
though the /proc/spl/kstat/zfs/dbgmsg kstat.  For user space consumers
log messages are immediately written to stdout after applying the
ZFS_DEBUG environment variable.

$ ZFS_DEBUG=on ./cmd/ztest/ztest -V

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #3728
2015-09-04 16:08:14 -07:00
Brian Behlendorf
0500e835af Support accessing .zfs/snapshot via NFS
This patch is based on the previous work done by @andrey-ve and
@yshui.  It triggers the automount by using kern_path() to traverse
to the known snapshout mount point.  Once the snapshot is mounted
NFS can access the contents of the snapshot.

Allowing NFS clients to access to the .zfs/snapshot directory would
normally mean that a root user on a client mounting an export with
'no_root_squash' would be able to use mkdir/rmdir/mv to manipulate
snapshots on the server.  To prevent configuration mistakes a
zfs_admin_snapshot module option was added which disables the
mkdir/rmdir/mv functionally.  System administators desiring this
functionally must explicitly enable it.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2797
Closes #1655
Closes #616
2015-09-04 13:23:53 -07:00
Andrey Vesnovaty
aa9b27080b Fix invalid fileid for snapshot root dentry
Prevents NFS client from detection of different fileids of snapshot root dentry
before & after snapshot mount.

Signed-off-by: Andrey Vesnovaty <andrey.vesnovaty@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2015-09-04 13:23:06 -07:00
Brian Behlendorf
e20cd6f7a8 Merge branch 'zvol'
Performance improvements for zvols.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3720
2015-09-04 13:14:21 -07:00
Richard Yao
fa56567630 Support secure discard on zvols
Linux 2.6.36 introduced REQ_SECURE to indicate when discards *must* be
processed, such that we cannot do optimizations like block alignment.
Consequently, the discard semantics prior to 2.6.36 require us to always
process unaligned discards. Previously, we would do this optimization
regardless. This patch changes things to correctly restrict this
optimization to situations where REQ_SECURE exists, but is not included
in the flags.

Signed-off-by: Richard Yao <ryao@gentoo.org>
2015-09-04 15:37:24 -04:00
Richard Yao
37f9dac592 zvol processing should use struct bio
Internally, zvols are files exposed through the block device API. This
is intended to reduce overhead when things require block devices.
However, the ZoL zvol code emulates a traditional block device in that
it has a top half and a bottom half. This is an unnecessary source of
overhead that does not exist on any other OpenZFS platform does this.
This patch removes it. Early users of this patch reported double digit
performance gains in IOPS on zvols in the range of 50% to 80%.

Comments in the code suggest that the current implementation was done to
obtain IO merging from Linux's IO elevator. However, the DMU already
does write merging while arc_read() should implicitly merge read IOs
because only 1 thread is permitted to fetch the buffer into ARC. In
addition, commercial ZFSOnLinux distributions report that regular files
are more performant than zvols under the current implementation, and the
main consumers of zvols are VMs and iSCSI targets, which have their own
elevators to merge IOs.

Some minor refactoring allows us to register zfs_request() as our
->make_request() handler in place of the generic_make_request()
function. This eliminates the layer of code that broke IO requests on
zvols into a top half and a bottom half. This has several benefits:

1. No per zvol spinlocks.
2. No redundant IO elevator processing.
3. Interrupts are disabled only when actually necessary.
4. No redispatching of IOs when all taskq threads are busy.
5. Linux's page out routines will properly block.
6. Many autotools checks become obsolete.

An unfortunate consequence of eliminating the layer that
generic_make_request() is that we no longer calls the instrumentation
hooks for block IO accounting. Those hooks are GPL-exported, so we
cannot call them ourselves and consequently, we lose the ability to do
IO monitoring via iostat.  Since zvols are internally files mapped as
block devices, this should be okay. Anyone who is willing to accept the
performance penalty for the block IO layer's accounting could use the
loop device in between the zvol and its consumer. Alternatively, perf
and ftrace likely could be used. Also, tools like latencytop will still
work. Tools such as latencytop sometimes provide a better view of
performance bottlenecks than the traditional block IO accounting tools
do.

Lastly, if direct reclaim occurs during spacemap loading and swap is on
a zvol, this code will deadlock. That deadlock could already occur with
sync=always on zvols. Given that swap on zvols is not yet production
ready, this is not a blocker.

Signed-off-by: Richard Yao <ryao@gentoo.org>
2015-09-04 15:30:24 -04:00
Tim Chase
dca8c34da4 Prevent reclaim in the traverse prefetch thread
Reclaim in the traverse prefetch thread, which is run on the system
taskq, can overrun the stack.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #3733
2015-09-04 08:43:28 -07:00
Brian Behlendorf
0282c4137e Add temporary mount options
Add the required kernel side infrastructure to parse arbitrary
mount options.  This enables us to support temporary mount
options in largely the same way it is handled on other platforms.

See the 'Temporary Mount Point Properties' section of zfs(8)
for complete details.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #985
Closes #3351
2015-09-03 14:14:55 -07:00
Tim Chase
69de34219a Dbuf hash table should be sized as is the arc hash table
Commit 49ddb31506 added the
zfs_arc_average_blocksize parameter to allow control over the size of
the arc hash table.  The dbuf hash table's size should be determined
similarly.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3721
2015-09-02 09:33:02 -07:00
Brian Behlendorf
6cde64351e Add spa_slop_shift module option
Allow for easy turning of a pools reserved free space.  Previous
versions of ZFS (v0.6.4 and earlier) held 1/64 of the pools capacity
in reserve.  Commits 3d45fdd and 0c60cc3 increased this to 1/32.
Setting spa_slop_shift=6 will restore the previous default setting.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3724
2015-09-02 09:30:18 -07:00
Richard Yao
fb40095f5f Disable LBA weighting on files and SSDs
The LBA weighting makes sense on rotational media where the outer tracks
have twice the bandwidth of the inner tracks. However, it is detrimental
on nonrotational media such as solid state disks, where the only effect
is to ensure that metaslabs enter the best-fit allocation behavior
sooner, which is detrimental to performance. It also makes no sense on
files where the underlying filesystem can arrange things however it
wants.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3712
2015-09-01 15:22:07 -07:00
tuxoko
cafbd2aca3 Check for RW_WRITE_HELD in zfs_inactive
Before read locking z_teardown_inactive_lock, we need to check if we have
already had write lock on it. Otherwise, we would deadlock on ourself when
doing rollback:

zfs_ioc_rollback
->zfs_suspend_fs (z_teardown_inactive_lock, RW_WRITER)
->zfs_resume_fs->zfs_rezget->zfs_iput_async->iput-> ...
  ->zfs_inactive (z_teardown_inactive_lock, RW_READER)

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2869
2015-09-01 10:17:57 -07:00
Brian Behlendorf
324dcd3733 Linux 4.2 compat: misc_deregister()
The misc_deregister() function was changed to a void return type.
Rather than add compatibility code to detect this change simply
ignore the return code on all kernels.  It was only used to log
an informational error message of no real value.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2015-09-01 09:33:18 -07:00
Brian Behlendorf
278bee9319 Linux 3.18 compat: Snapshot auto-mounting
Re-factor the .zfs/snapshot auto-mouting code to take in to account
changes made to the upstream kernels.  And to lay the groundwork for
enabling access to .zfs snapshots via NFS clients.  This patch makes
the following core improvements.

* All actively auto-mounted snapshots are now tracked in two global
trees which are indexed by snapshot name and objset id respectively.
This allows for fast lookups of any auto-mounted snapshot regardless
without needing access to the parent dataset.

* Snapshot entries are added to the tree in zfsctl_snapshot_mount().
However, they are now removed from the tree in the context of the
unmount process.  This eliminates the need complicated error logic
in zfsctl_snapshot_unmount() to handle unmount failures.

* References are now taken on the snapshot entries in the tree to
ensure they always remain valid while a task is outstanding.

* The MNT_SHRINKABLE flag is set on the snapshot vfsmount_t right
after the auto-mount succeeds.  This allows to kernel to unmount
idle auto-mounted snapshots if needed removing the need for the
zfsctl_unmount_snapshots() function.

* Snapshots in active use will not be automatically unmounted.  As
long as at least one dentry is revalidated every zfs_expire_snapshot/2
seconds the auto-unmount expiration timer will be extended.

* Commit torvalds/linux@bafc9b7 caused snapshots auto-mounted by ZFS
to be immediately unmounted when the dentry was revalidated.  This
was a consequence of ZFS invaliding all snapdir dentries to ensure that
negative dentries didn't mask new snapshots.  This patch modifies the
behavior such that only negative dentries are invalidated.  This solves
the issue and may result in a performance improvement.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3589
Closes #3344
Closes #3295
Closes #3257
Closes #3243
Closes #3030
Closes #2841
2015-08-31 13:54:39 -07:00
Andrey Vesnovaty
b23975cbe0 zfsctl: No need to sync ctldir inodes
There's no metadata to write to disk for ctldir inodes. So we check if
a inode belongs to the ctldir in zpl_commit_metadata, and returns
immediately if it is.

Signed-off-by: Andrey Vesnovaty <andrey.vesnovaty@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2797
2015-08-31 13:54:39 -07:00
Richard Yao
c6a3a222d3 Clear QUEUE_FLAG_ADD_RANDOM on zvols
zvols should not be an entropy source for the kernel. Disable it to be
consistent with the upstream kernel.

torvalds/linux@b277da0a8a

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3713
2015-08-30 10:11:57 -07:00
loli10K
3757bff3b1 Fix small typo
Add a missing space to the zfs_vdev_sync_write_min_active module
parameter description.

Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3714
2015-08-30 10:10:16 -07:00
Tim Chase
36b454ab4c Initialize the taskq entry embedded within struct vdev
As part of the stack reduction effort in
50b25b2187, a zio_t containing a taskq_ent
was added to struct vdev_queue which itself is part of struct vdev.
The taskq entry should be initialized as is currently done in zio_create()
for newly-created bare zio_t object.  The rationale is the same as is
described in f467b05a26.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3709
2015-08-30 10:04:56 -07:00
Tim Chase
d439f63ff5 Allow recovery from corrupted snapshot maps
If the ZAP object containing a snapshot map is corrupted due to an
unrecoverable checksum error or otherwise, dsl_dataset_name() will
normally panic the system due to its VERIFY.

This patch attempts to allow a recovery avenue from such situations by
manufacturing a descriptive snapshot name and then ignoring the error.
Scrubbing a pool with this type of corruption will then show the affected
object in the error list rather than panicking.

The recovery code is only enabled when the zfs_recover module parameter
is set.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3705
2015-08-28 11:56:32 -07:00
Brian Behlendorf
4cb7b9c5d4 Check large block feature flag on volumes
Since ZoL allows large blocks to be used by volumes, unlike upstream
illumos, the feature flag must be checked prior to volume creation.
This is critical because unlike filesystems, volumes will create a
object which uses large blocks as part of the create.  Therefore, it
cannot be safely checked in zfs_check_settable() after the dataset
can been created.

In addition this patch updates the relevant error messages to use
zfs_nicenum() to print the maximum blocksize.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3591
2015-08-28 09:25:03 -07:00
Brian Behlendorf
c495fe2c1c Limit max_hw_sectors_kb to 16M
When support for large blocks was added DMU_MAX_ACCESS was increased
to allow for blocks of up to 16M to fit in a transaction handle.
This had the side effect of increasing the max_hw_sectors_kb for
volumes, which are scaled off DMU_MAX_ACCESS, to 64M from 10M.

This is an issue for volumes which by default use an 8K block size
because it results in dmu_buf_hold_array_by_dnode() allocating a
64K array for the dbufs.  The solution is to restore the maximum
size to ~10M.  This patch specifically changes it to 16M which is
close enough.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3684
2015-08-28 09:16:59 -07:00
Chunwei Chen
5475aada94 Linux 4.1 compat: loop device on ZFS
Starting from Linux 4.1 allows iov_iter with bio_vec to be passed into
iter_read/iter_write. Notably, the loop device will pass bio_vec to backend
filesystem. However, current ZFS code assumes iovec without any check, so it
will always crash when using loop device.

With the restructured uio_t, we can safely pass bio_vec in uio_t with UIO_BVEC
set. The uio* functions are modified to handle bio_vec case separately.

The const uio_iov causes some warning in xuio related stuff, so explicit
convert them to non const.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3511
Closes #3640
2015-08-24 10:17:06 -07:00
Brian Behlendorf
efc412b645 Linux 4.2 compat: vfs_rename()
The spa_config_write() function relies on the classic method of
making sure updates to the /etc/zfs/zpool.cache file are atomic.
It writes out a temporary version of the file and then uses
vn_rename() to switch it in to place.  This way there can never
exist a partial version of the file, it's all or nothing.

Conceptually this is a good strategy and it makes good sense
for platforms where it's easy to do a rename within the kernel.
Unfortunately, Linux is not one of those platforms.  Even doing
basic I/O to a file system from within the kernel is strongly
discouraged.  In order to support this at all the vn_rename()
implementation ends up being complex and fragile.  So fragile
that recent Linux 4.2 changes have broken it.

While it is possible to update vn_rename() to work with the
latest kernels a better long term strategy is to stop using
vn_rename() entirely.  Then all this complex, fragile code can
be removed.  Achieving this is straight forward because
config_write() is the only consumer of vn_rename().

This patch reworks spa_config_write() to update the cache file
in place.  The file will be truncated, written out, and then
synced to disk.  If an error is encountered the file will be
unlinked leaving the system in a consistent state.

This does expose a tiny tiny tiny window where a system could
crash at exactly the wrong moment could leave a partially written
cache file.  However, this is highly unlikely because the cache
file is 1) infrequently updated, 2) only a few kilobytes in size,
and 3) written with a single vn_rdwr() call.

If this were to somehow happen it poses no risk to pool.  Simply
removing the cache file will allow the pool to be imported cleanly.
Going forward this will be even less of an issue as we intend to
disable the use of a cache file by default.

Bottom line not using vn_rename() allows us to make ZoL more
robust against upstream kernel changes.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3653
2015-08-19 16:04:33 -07:00
Brian Behlendorf
ff9b1d0725 Handle zap_lookup() failure in ddt_object_load()
Failing to lookup a name in the spa_ddt_stat_object should not result
in a panic in ddt_object_load().  The error can be safely returned to
the caller for handling resulting in a useful user error message.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3370
2015-08-19 14:32:50 -07:00
tuxoko
6d79eabf9f Add parenthesis to the ternary operator
Without the parenthesis, this particular ASSERT will evaluate to
"(RW_READER == (!zap->zap_ismicro && fatreader)) ? RW_READER : lti"

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3685
2015-08-19 11:28:41 -07:00
Brian Behlendorf
7e8bddd019 Update arc_memory_throttle() to check pageout
This brings the behavior of arc_memory_throttle() back in sync with
illumos.  The updated memory throttling policy roughly goes like this:

* Never throttle if more than 10% of memory is free.  This threshold
  is configurable with the zfs_arc_lotsfree_percent module option.

* Minimize any throttling of kswapd even when free memory is below
  the set threshold.  Allow it to write out pages as quickly as
  possible to help alleviate the memory pressure.

* Delay all other threads when free memory is below the set threshold
  in order to avoid compounding the memory pressure.  Buffers will be
  evicted from the ARC to reduce the issue.

The Linux specific zfs_arc_memory_throttle_disable module option has
been removed in favor of the existing zfs_arc_lotsfree_percent tuning.
Setting zfs_arc_lotsfree_percent=0 will have the same effect as
zfs_arc_memory_throttle_disable and it was therefore redundant.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3637
2015-07-30 11:52:12 -07:00
Brian Behlendorf
11f552fa90 Update arc_available_memory() to check freemem
While Linux doesn't provide detailed information about the state of
the VM it does provide us total free pages.  This information should
be incorporated in to the arc_available_memory() calculation rather
than solely relying on a signal from direct reclaim.  Conceptually
this brings arc_available_memory() back in sync with illumos.

It is also desirable that the target amount of free memory be tunable
on a system.  While the default values are expected to work well
for most workloads there may be cases where custom values are needed.
The zfs_arc_sys_free module option was added for this purpose.

zfs_arc_sys_free - The target number of bytes the ARC should leave
                   as free memory on the system.  This value can
                   checked in /proc/spl/kstat/zfs/arcstats and
                   setting this module option will override the
                   default value.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3637
2015-07-30 11:50:22 -07:00
Brian Behlendorf
6339c1b9dc Bound zvol_threads module option
The zvol_threads module option should be bounded to a reasonable
range.  The taskq must have at least 1 thread and shouldn't have
more than 1,024 at most.  The default value of 32 is a reasonable
default.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3614
2015-07-29 07:42:11 -07:00
Chunwei Chen
21a96fb635 Fix "BUG: Bad page state" caused by writeback flag
Commit d958324 fixed the deadlock between page lock and range lock by
unlocking the page lock before acquiring the range lock. However,
this created a new issue #3075.

The problem is that if we can't set the write back bit before releasing
the page lock.  Then other processes will be unaware that the page is
under active write back.  They may therefore truncate the page,
invalidate the page, or not honor the sync semantics.

To workaround this problem we re-dirty the page before dropping the
page lock.  While this doesn't prevent the page from being truncated
it does ensure it won't be invalidated.  Then the range lock and the
page lock are reacquired in the correct deadlock-free order.

Once both locks are safely held the page state can be rechecked.  If
all is well and the page is in the expect state the dirty bit can be
removed, the write back bit set, and the page removed from the skip
count.  If not the page will be handled as appropriate.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3075
2015-07-29 07:38:15 -07:00
Brian Behlendorf
1229323d5f Align thread priority with Linux defaults
Under Linux filesystem threads responsible for handling I/O are
normally created with the maximum priority.  Non-I/O filesystem
processes run with the default priority.  ZFS should adopt the
same priority scheme under Linux to maintain good performance
and so that it will complete fairly when other Linux filesystems
are active.  The priorities have been updated to the following:

$ ps -eLo rtprio,cls,pid,pri,nice,cmd | egrep 'z_|spl_|zvol|arc|dbu|meta'
     -  TS 10743  19 -20 [spl_kmem_cache]
     -  TS 10744  19 -20 [spl_system_task]
     -  TS 10745  19 -20 [spl_dynamic_tas]
     -  TS 10764  19   0 [dbu_evict]
     -  TS 10765  19   0 [arc_prune]
     -  TS 10766  19   0 [arc_reclaim]
     -  TS 10767  19   0 [arc_user_evicts]
     -  TS 10768  19   0 [l2arc_feed]
     -  TS 10769  39   0 [z_unmount]
     -  TS 10770  39 -20 [zvol]
     -  TS 11011  39 -20 [z_null_iss]
     -  TS 11012  39 -20 [z_null_int]
     -  TS 11013  39 -20 [z_rd_iss]
     -  TS 11014  39 -20 [z_rd_int_0]
     -  TS 11022  38 -19 [z_wr_iss]
     -  TS 11023  39 -20 [z_wr_iss_h]
     -  TS 11024  39 -20 [z_wr_int_0]
     -  TS 11032  39 -20 [z_wr_int_h]
     -  TS 11033  39 -20 [z_fr_iss_0]
     -  TS 11041  39 -20 [z_fr_int]
     -  TS 11042  39 -20 [z_cl_iss]
     -  TS 11043  39 -20 [z_cl_int]
     -  TS 11044  39 -20 [z_ioctl_iss]
     -  TS 11045  39 -20 [z_ioctl_int]
     -  TS 11046  39 -20 [metaslab_group_]
     -  TS 11050  19   0 [z_iput]
     -  TS 11121  38 -19 [z_wr_iss]

Note that under Linux the meaning of a processes priority is inverted
with respect to illumos.  High values on Linux indicate a _low_ priority
while high value on illumos indicate a _high_ priority.

In order to preserve the logical meaning of the minclsyspri and
maxclsyspri macros when they are used by the illumos wrapper functions
their values have been inverted.  This way when changes are merged
from upstream illumos we won't need to remember to invert the macro.
It could also lead to confusion.

This patch depends on https://github.com/zfsonlinux/spl/pull/466.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #3607
2015-07-28 13:36:47 -07:00
Brian Behlendorf
c97d30691c Check for NULL in dmu_free_long_range_impl()
A NULL should never be passed as the dnode_t pointer to the function
dmu_free_long_range_impl().  Regardless, because we have a reported
occurrence of this let's add some error handling to catch this.
Better to report a reasonable error to caller than panic the system.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3445
2015-07-28 13:30:53 -07:00
Brian Behlendorf
96c080cb9c Minor style cleanup
Address minor differences in style between upstream and ZoL.  This
patch contains no functional differences and is solely designed to
minimize the delta from upstream.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3533
2015-07-23 09:42:54 -07:00
Brian Behlendorf
3056818343 Remove double counting HDR_L2ONLY_SIZE
Commit d962d5d didn't quite properly resolve the HDR_L2ONLY_SIZE
accounting.  Accounting is now performed only in the constructor
and destructor which is a nice simplification.  It should have
been removed the from create and destroy functions.  This brings
up back in sync with upstream.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3533
2015-07-23 09:42:44 -07:00
Brian Behlendorf
8c8af9d807 Add hdr_recl() reclaim callback
Originally removed because it wasn't required under Linux.  However,
there may still be some utility in signaling the arc reclaim thread
under Linux via reclaim.  This should already have happened by other
means but it's not harmless and reduces another point of divergence
with upstream.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3533
2015-07-23 09:42:40 -07:00
Brian Behlendorf
728d6ae91e Reinstate zfs_arc_p_min_shift
Commit f521ce1 removed the minimum value for "arc_p" allowing it to
drop to zero or grow to "arc_c".  This was done to improve specific
workload which constantly dirties new "metadata" but also frequently
touches a "small" amount of mfu data (e.g. mkdir's).

This change may still be desirable but it needs to be re-investigated.
in the context of the recent ARC changes from upstream.  Therefore
this code is being restored to facilitate benchmarking.  By setting
"zfs_arc_p_min_shift=64" we easily compare the performance.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3533
2015-07-23 09:42:32 -07:00
Prakash Surya
36da08ef9b Illumos 5817 - change type of arcs_size from uint64_t to refcount_t
5817 change type of arcs_size from uint64_t to refcount_t
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Richard Elling <richard.elling@richardelling.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/5817
  https://github.com/illumos/illumos-gate/commit/2fd872a

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3533
2015-07-23 09:42:28 -07:00
Prakash Surya
500445c046 Illumos 5445 - Add more visibility via arcstats
5445 Add more visibility via arcstats; specifically arc_state_t
stats and differentiate between "data" and "metadata"
Reviewed by: Basil Crow <basil.crow@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Bayard Bell <bayard.bell@nexenta.com>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  https://www.illumos.org/issues/5445
  https://github.com/illumos/illumos-gate/commit/4076b1b

Porting Notes:

This patch is an improved version of cc7f677 which was previously
merged in ZoL.  This patch incorporates the additional improvements
which were made upstream.

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3533
2015-07-23 09:42:06 -07:00
Matthew Ahrens
ca67b33aba Illumos 5376 - arc_kmem_reap_now() should not result in clearing arc_no_grow
5376 arc_kmem_reap_now() should not result in clearing arc_no_grow
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Reviewed by: Richard Elling <richard.elling@richardelling.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/issues/5376
  https://github.com/illumos/illumos-gate/commit/2ec99e3

Porting Notes:

The good news is that many of the recent changes made upstream to the
ARC tackled issues previously observed by ZoL with similar solutions.
The bad news is those solution weren't identical to the ones we applied.
This patch is designed to split the difference and apply as much of the
upstream work as possible.

* The arc_available_memory() function was removed previous in ZoL but
due to the upstream changes it makes sense to add it back.  This function
has been customized for Linux so that it can be used to determine a low
memory.  This provides the same basic functionality as the illumos version
allowing us to minimize changes through the rest of the code base.  The
exact mechanism used to detect a low memory state remains unchanged so
this change isn't a significant as it might first appear.

* This patch includes the long standing fix for arc_shrink() which was
originally proposed in #2167.  Since there were related changes to this
function it made sense to include that work.

* The arc_init() function has been re-factored.  As before it sets sane
default values for the ARC but then calls arc_tuning_update() to apply
user specific tuning made via module options.  The arc_tuning_update()
function is then called periodically by the arc_reclaim_thread() to
apply changes to the tunings made during normal operation.

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3616
Closes #2167
2015-07-23 09:41:28 -07:00