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* Support accessing .zfs/snapshot via NFSBrian Behlendorf2015-09-043-0/+141
| | | | | | | | | | | | | | | | | | | | 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 <[email protected]> Closes #2797 Closes #1655 Closes #616
* Fix invalid fileid for snapshot root dentryAndrey Vesnovaty2015-09-041-0/+10
| | | | | | | | Prevents NFS client from detection of different fileids of snapshot root dentry before & after snapshot mount. Signed-off-by: Andrey Vesnovaty <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]>
* Merge branch 'zvol'Brian Behlendorf2015-09-0421-700/+288
|\ | | | | | | | | | | | | | | Performance improvements for zvols. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3720
| * Remove blk_queue_nonrot() autotools checkRichard Yao2015-09-042-26/+0
| | | | | | | | | | | | | | | | | | | | This autotools check was never needed because we can check for the existence of QUEUE_FLAG_NONROT in the kernel headers. Also, the comment in config/kernel-blk-queue-nonrot.m4 is incorrect. This was a Linux 2.6.28 API change, not a Linux 2.6.27 API change. Signed-off-by: Richard Yao <[email protected]>
| * Remove blk_queue_discard() autotools checkRichard Yao2015-09-042-23/+0
| | | | | | | | | | | | | | This autotools check was never needed because we can check for the existence of QUEUE_FLAG_DISCARD in the kernel headers. Signed-off-by: Richard Yao <[email protected]>
| * Remove blk_rq_bytes()/blk_rq_sectors autotools checksRichard Yao2015-09-044-87/+0
| | | | | | | | Signed-off-by: Richard Yao <[email protected]>
| * Remove blk_rq_pos() autotools checkRichard Yao2015-09-043-30/+0
| | | | | | | | Signed-off-by: Richard Yao <[email protected]>
| * Remove blk_fetch_request() autotools checkRichard Yao2015-09-043-40/+0
| | | | | | | | Signed-off-by: Richard Yao <[email protected]>
| * Remove blk_requeue_request() autotools checkRichard Yao2015-09-043-34/+0
| | | | | | | | Signed-off-by: Richard Yao <[email protected]>
| * Remove blk_end_request() autotools check.Richard Yao2015-09-043-115/+0
| | | | | | | | Signed-off-by: Richard Yao <[email protected]>
| * Remove rq_is_sync() autotools checkRichard Yao2015-09-043-30/+0
| | | | | | | | Signed-off-by: Richard Yao <[email protected]>
| * Remove rq_for_each_segment() autotools checkRichard Yao2015-09-043-90/+0
| | | | | | | | Signed-off-by: Richard Yao <[email protected]>
| * Support secure discard on zvolsRichard Yao2015-09-041-7/+12
| | | | | | | | | | | | | | | | | | | | | | | | 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 <[email protected]>
| * zvol processing should use struct bioRichard Yao2015-09-0411-218/+276
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <[email protected]>
| * VDEV_REQ_FUA should be mapped to REQ_FUARichard Yao2015-09-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | Pre-2.6.37 kernels support REQ_FUA in request flags, but not in BIO flags. zvols are the only consumer of VDEV_REQ_FUA and since they are passed requests, they should be obey the REQ_FUA flag like later kernels. This optimization will only matter on 2.6.36 and 2.6.37 because the zvol rework changes things to use bio, where we no longer are able to distinguish on earlier kernels Signed-off-by: Richard Yao <[email protected]>
* | Prevent reclaim in the traverse prefetch threadTim Chase2015-09-041-0/+2
| | | | | | | | | | | | | | | | | | Reclaim in the traverse prefetch thread, which is run on the system taskq, can overrun the stack. Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Closes #3733
* | Add temporary mount optionsBrian Behlendorf2015-09-0313-62/+332
|/ | | | | | | | | | | | | 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 <[email protected]> Closes #985 Closes #3351
* Dbuf hash table should be sized as is the arc hash tableTim Chase2015-09-022-3/+7
| | | | | | | | | | | Commit 49ddb315066e372f31bda29a5c546a9eccc8b418 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 <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3721
* Add spa_slop_shift module optionBrian Behlendorf2015-09-022-0/+19
| | | | | | | | | | 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 <[email protected]> Closes #3724
* Reorder zfs-* services to allow /var on separate datasetJames Lee2015-09-025-46/+45
| | | | | | | | | | | | | | | | | | | | | | | | | ZED depends on /var. When /var is a separate dataset, it must be mounted before starting ZED. This change moves the zfs-zed service from starting first, to starting after zfs-mount, but before zfs-share. As discussed in issue #3513, ZED does not need to start first in order to consume events made during the zfs-import and zfs-mount services. The events will be queued and can be handled later in the boot process. ZED may, however, handle sharing in the future, so it should be started before the zfs-share service. This commit also stops the zfs-import service from writing temp files to /var/tmp on shutdown and it corrects the return code for the OpenRC service. Other OpenRC-specific changes noted in issue #3513 were reitereated in issue #3715 and committed in da619f3. Signed-off-by: James Lee <[email protected]> Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3513
* Disable LBA weighting on files and SSDsRichard Yao2015-09-015-2/+17
| | | | | | | | | | | | | | 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 <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3712
* Check for RW_WRITE_HELD in zfs_inactivetuxoko2015-09-011-3/+10
| | | | | | | | | | | | | | | 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 <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #2869
* Remove blk_queue_io_opt() autotools checkRichard Yao2015-09-013-34/+0
| | | | | | | | This is needed for supporting kernels earlier than 2.6.30. Support for those kernels was dropped, so we can safely remove this check. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]>
* Remove blk_queue_physical_block_size() autotools checkRichard Yao2015-09-013-36/+0
| | | | | | | | This is needed for supporting kernels earlier than 2.6.30. Support for those kernels was dropped, so we can safely remove this check. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]>
* Linux 4.2 compat: misc_deregister()Brian Behlendorf2015-09-012-10/+2
| | | | | | | | | 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 <[email protected]>
* Linux 3.18 compat: Snapshot auto-mountingBrian Behlendorf2015-08-3113-419/+496
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <[email protected]> Closes #3589 Closes #3344 Closes #3295 Closes #3257 Closes #3243 Closes #3030 Closes #2841
* zfsctl: No need to sync ctldir inodesAndrey Vesnovaty2015-08-311-0/+3
| | | | | | | | | | 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 <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #2797
* Clear QUEUE_FLAG_ADD_RANDOM on zvolsRichard Yao2015-08-301-0/+3
| | | | | | | | | | | zvols should not be an entropy source for the kernel. Disable it to be consistent with the upstream kernel. torvalds/linux@b277da0a8a594308e17881f4926879bd5fca2a2d Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3713
* Fix small typololi10K2015-08-301-1/+1
| | | | | | | | | | Add a missing space to the zfs_vdev_sync_write_min_active module parameter description. Signed-off-by: loli10K <[email protected]> Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3714
* Some OpenRC dependency logic belongs in mountRichard Yao2015-08-302-10/+12
| | | | | | | | | The dependencies for handling / on ZFS belong in the mount script, not the zed script. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3715
* Initialize the taskq entry embedded within struct vdevTim Chase2015-08-301-0/+1
| | | | | | | | | | | | | As part of the stack reduction effort in 50b25b2187134ac7b19cf93bd35a420223f1d343, 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 f467b05a265abcfb8e5a3269f79d08f36a58646a. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3709
* Add extra keyword 'slot' to vdev_id.confAndreas Buschmann2015-08-302-1/+40
| | | | | | | | | | | Add new keyword 'slot' to vdev_id.conf This selects from where to get the slot number for a SAS/SATA disk Needed to enable access to the physical position of a disk in a Supermicro 2027R-AR24NV . Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Ned Bass <[email protected]> Closes #3693
* Allow recovery from corrupted snapshot mapsTim Chase2015-08-281-0/+6
| | | | | | | | | | | | | | | | | | 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 <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3705
* Check large block feature flag on volumesBrian Behlendorf2015-08-284-5/+36
| | | | | | | | | | | | | | | 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 <[email protected]> Closes #3591
* Limit max_hw_sectors_kb to 16MBrian Behlendorf2015-08-281-1/+1
| | | | | | | | | | | | | | | | 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 <[email protected]> Closes #3684
* Linux 4.1 compat: loop device on ZFSChunwei Chen2015-08-245-137/+162
| | | | | | | | | | | | | | | | | | | 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 <[email protected]> Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3511 Closes #3640
* Add compatibility layer for {kmap,kunmap}_atomicChunwei Chen2015-08-244-1/+63
| | | | | | | | | Starting from linux-2.6.37, {kmap,kunmap}_atomic takes 1 argument instead of 2. We use zfs_{kmap,kunmap}_atomic as wrappers and always take 2 argument, but ignore the 2nd for newer kernel. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]>
* Linux 4.2 compat: vfs_rename()Brian Behlendorf2015-08-191-0/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <[email protected]> Closes #3653
* Handle zap_lookup() failure in ddt_object_load()Brian Behlendorf2015-08-191-3/+4
| | | | | | | | | 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 <[email protected]> Closes #3370
* Fix zvol detectionRichard Yao2015-08-191-0/+6
| | | | | | | | | The zpool create subcomand should not return an error on debug builds of the userland tools when given zvols. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3595
* Add parenthesis to the ternary operatortuxoko2015-08-191-1/+1
| | | | | | | | | Without the parenthesis, this particular ASSERT will evaluate to "(RW_READER == (!zap->zap_ismicro && fatreader)) ? RW_READER : lti" Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3685
* Fix build failure with Linux 4.1 and FTRACEChris Dunlop2015-08-181-0/+3
| | | | | | | | See also #3546, commit c1718e9 Signed-off-by: Chris Dunlop <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3673
* Linux 4.1 compat: configure bdi_setup_and_register()Chris Dunlop2015-08-181-2/+2
| | | | | | | | | | Pull struct backing_dev_info off the stack: by linux-4.1 it's grown past our 1024 byte stack frame warning limit resulting in an incorrect configure result. Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Chris Dunlop <[email protected]> Closes #3671
* ztest: display non-index properties properly at verbose level 6Tim Chase2015-07-301-3/+10
| | | | | | | | | | | | At verbosity levels of 6 or greater, ztest_dsl_prop_set_uint64() attempts to display the value of all properties as indexed values regardless of whether the property is an indexed value or simply an un-indexed integer. This patch causes the numeric value of the property to be displayed if zfs_prop_index_to_string() fails. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3649
* Rework zed_notify_email for configurable PROG/OPTSChris Dunlap2015-07-302-11/+51
| | | | | | | | | | | | | | | | | | | | | | | This commit reworks the zed_notify_email() function to allow configuration of the mail executable and command-line arguments. ZED_EMAIL_PROG specifies the name or path of the executable responsible for sending notifications via email. This variable defaults to "mail". ZED_EMAIL_OPTS specifies command-line options passed to ZED_EMAIL_PROG. The following keyword substitutions are performed: - @ADDRESS@ is replaced with the recipient email address(es) - @SUBJECT@ is replaced with the notification subject This variable defaults to "-s '@SUBJECT@' @ADDRESS@". ZED_EMAIL_ADDR replaces ZED_EMAIL (although the latter is retained for backward compatibility). This variable can contain multiple addresses as long as they are delimited by whitespace. Signed-off-by: Chris Dunlap <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3634 Closes #3631
* Fix whitespace in zed_log_errChris Dunlap2015-07-301-1/+1
| | | | | | | | This commit fixes the two adjacent spaces that appear in zed_log_err() messages when ZEVENT_EID is undefined. Signed-off-by: Chris Dunlap <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]>
* Update arc_memory_throttle() to check pageoutBrian Behlendorf2015-07-302-13/+44
| | | | | | | | | | | | | | | | | | | | | | | | 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 <[email protected]> Closes #3637
* Update arc_available_memory() to check freememBrian Behlendorf2015-07-302-31/+46
| | | | | | | | | | | | | | | | | | | | | | 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 <[email protected]> Closes #3637
* Bound zvol_threads module optionBrian Behlendorf2015-07-292-4/+5
| | | | | | | | | | 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 <[email protected]> Closes #3614
* Fix "BUG: Bad page state" caused by writeback flagChunwei Chen2015-07-291-0/+50
| | | | | | | | | | | | | | | | | | | | | | | | | 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 <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3075
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