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* Disable EDONR on FreeBSDMatthew Macy2019-12-052-0/+5
| | | | | | | | | | | FreeBSD uses its own crypto framework in-kernel which, at this time, has no EDONR implementation. Reviewed-by: Jorgen Lundman <[email protected]> Reviewed-by: Allan Jude <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matt Macy <[email protected]> Signed-off-by: Ryan Moeller <[email protected]> Closes #9664
* Increase allowed 'special_small_blocks' maximum valueBrian Behlendorf2019-12-031-1/+1
| | | | | | | | | | | | | | There may be circumstances where it's desirable that all blocks in a specified dataset be stored on the special device. Relax the artificial 128K limit and allow the special_small_blocks property to be set up to 1M. When blocks >1MB have been enabled via the zfs_max_recordsize module option, this limit is increased accordingly. Reviewed-by: Don Brady <[email protected]> Reviewed-by: Kjeld Schouten <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #9131 Closes #9355
* Remove zfs_vdev_elevator module optionBrian Behlendorf2019-11-271-14/+0
| | | | | | | | | | | | | As described in commit f81d5ef6 the zfs_vdev_elevator module option is being removed. Users who require this functionality should update their systems to set the disk scheduler using a udev rule. Reviewed-by: Richard Laager <[email protected]> Reviewed-by: loli10K <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #8664 Closes #9417 Closes #9609
* Add display of checksums to zdb -RPaul Zuchowski2019-11-271-0/+2
| | | | | | | | | | | | | | | The function zdb_read_block (zdb -R) was always intended to have a :c flag which would read the DVA and length supplied by the user, and display the checksum. Since we don't know which checksum goes with the data, we should calculate and display them all. For each checksum in the table, read in the data at the supplied DVA:length, calculate the checksum, and display it. Update the man page and create a zfs test for the new feature. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Kjeld Schouten <[email protected]> Signed-off-by: Paul Zuchowski <[email protected]> Closes #9607
* Change zed.service to zfs-zed.service in man pageKjeld Schouten2019-11-131-2/+2
| | | | | | | | zed.service does not exist replaced with correct service name in man. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Kjeld Schouten-Lebbing <[email protected]> Closes #9581
* Reorganize zpool(8) man page into sectionsRoss Williams2019-11-1337-2446/+3959
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Moved subcommand topics into individual manpages. Reordered and grouped the list of subcommands by topic. Moved concepts overview to `zpoolconcepts.8` and the long list of available pool properties to `zpoolprops.8`. Internal cross-references copied from `zpool.8` needed to be converted to `.Xr` external references to new subcommand manual pages. Move `autotrim` into lexical order, autotrim tacked onto the end of a list. Now it is in alphabetical order. Clarify attach/detach description. Description was too specific to command syntax. Overview clarifies reason for attaching or detaching a device. Clarify replace description, don't refer to subcommand arguments. Clarify split command description, say what split actually does and why you'd want to do it. Clarify description of upgrade, and simplify the zpool.8 wording of the zpool-upgrade(8) description. Clarify description of import, detail what zpool-import(8) actually does. Add appropriate SEE ALSO sections. Divided zpool subcommand manual pages need their own SEE ALSO sections. Also modified fsck.zfs.8 to point directly to zfs-scrub.8 and zed.8.in to include a direct reference to zfs-events.8 Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Kjeld Schouten <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Ross Williams <[email protected]> Closes #9564
* Reorganize zfs(8) man page into sectionsRoss Williams2019-11-1236-4801/+5972
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Most subcommands got their own manpages (e.g. create). Some related commands grouped into a single manpage and symlinks created (e.g. set, get, and inherit). I did this when topics were either too short to warrant their own file or so interrelated that a user would want to refer between commands in the same file. Corrected .Sx internal references to .Xr cross refs; lots of .Sx references from when text was all in zfs.8 needed to be changed to .Xr zfs-$SUBCOMMAND 8 cross references. Divided subcommand list in zfs(8) into sections of related functionality. This required writing new descriptions for some commands. Preserved ".Os Linux", `.Os` macro parsing behavior differs between mandoc from the "BSD" mandoc package (available on Ubuntu) and man from Ubuntu's man-db package, which calls groff to format the manpages. Groff handles the `.Os` macro differently and wrongly, defaulting it to "BSD" in `/usr/share/groff/*/tmac/mdoc/doc-common`, instead of getting the default from `uname`. A future set of changes will introduce build-time preprocessing of manpages for platform-specific documentation and can insert the correct operating system name. Added SEE ALSO sections, the newly-divided zfs-*.8 subcommand man pages needed their own SEE ALSO sections pointing to related subcommands and, in some cases, documentation from other packages (e.g. zfs-share.8). Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Kjeld Schouten <[email protected]> Reviewed-by: Sean Eric Fagan <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Ross Williams <[email protected]> Closes #9559
* Add AVX512BW variant of fletcherRomain Dolbeau2019-10-301-1/+1
| | | | | | | | | | | It is much faster than AVX512F when byteswapping on Skylake-SP and newer, as we can do the byteswap in a single vshufb instead of many instructions. Reviewed by: Gvozden Neskovic <[email protected]> Reviewed-by: Chunwei Chen <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Romain Dolbeau <[email protected]> Closes #9517
* Modify sharenfs=on default behaviorBrian Behlendorf2019-10-131-1/+1
| | | | | | | | | | | | While it may sometimes be convenient to export an NFS filesystem with no_root_squash it should not be the default behavior. Align the default behavior with the Linux NFS server defaults. To restore the previous behavior use 'zfs set sharenfs="no_root_squash,..."'. Reviewed-by: loli10K <[email protected]> Reviewed-by: Richard Laager <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #9397 Closes #9425
* Implement ZPOOL_IMPORT_UDEV_TIMEOUT_MSRichard Yao2019-10-111-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since 0.7.0, zpool import would unconditionally block on udev for 30 seconds. This introduced a regression in initramfs environments that lack udev (particularly mdev based environments), yet use a zfs userland tools intended for the system that had been built against udev. Gentoo's genkernel is the main example, although custom user initramfs environments would be similarly impacted unless special builds of the ZFS userland utilities were done for them. Such environments already have their own mechanisms for blocking until device nodes are ready (such as genkernel's scandelay parameter), so it is unnecessary for zpool import to block on a non-existent udev until a timeout is reached inside of them. Rather than trying to intelligently determine whether udev is available on the system to avoid unnecessarily blocking in such environments, it seems best to just allow the environment to override the timeout. I propose that we add an environment variable called ZPOOL_IMPORT_UDEV_TIMEOUT_MS. Setting it to 0 would restore the 0.6.x behavior that was more desirable in mdev based initramfs environments. This allows the system user land utilities to be reused when building mdev-based initramfs archives. Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: Jorgen Lundman <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Georgy Yakovlev <[email protected]> Signed-off-by: Richard Yao <[email protected]> Closes #9436
* Update `zfs program` command usageBrian Behlendorf2019-10-101-2/+4
| | | | | | | | | | | | | | | | | Update the zfs(8) man page to clearly describe that arguments for channel programs are to be listed after the -- sentinel which terminates argument processing. This behavior is supported by getopt on Linux, FreeBSD, and Illumos according to each platforms respective man pages. zfs program [-jn] [-t instruction-limit] [-m memory-limit] pool script [--] arg1 ... Reviewed-by: Clint Armstrong <[email protected]> Reviewed-by: George Melikov <[email protected]> Reviewed-by: loli10K <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #9056 Closes #9428
* Add warning for zfs_vdev_elevator option removalBrian Behlendorf2019-09-251-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | Originally the zfs_vdev_elevator module option was added as a convenience so the requested elevator would be automatically set on the underlying block devices. At the time this was simple because the kernel provided an API function which did exactly this. This API was then removed in the Linux 4.12 kernel which prompted us to add compatibly code to set the elevator via a usermodehelper. While well intentioned this introduced a bug which could cause a system hang, that issue was subsequently fixed by commit 2a0d4188. In order to avoid future bugs in this area, and to simplify the code, this functionality is being deprecated. A console warning has been added to notify any existing consumers and the documentation updated accordingly. This option will remain for the lifetime of the 0.8.x series for compatibility but if planned to be phased out of master. Reviewed-by: Richard Laager <[email protected]> Reviewed-by: loli10K <[email protected]> Reviewed-by: Tony Hutter <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #8664 Closes #9317
* Add subcommand to wait for background zfs activity to completeJohn Gallagher2019-09-132-9/+104
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently the best way to wait for the completion of a long-running operation in a pool, like a scrub or device removal, is to poll 'zpool status' and parse its output, which is neither efficient nor convenient. This change adds a 'wait' subcommand to the zpool command. When invoked, 'zpool wait' will block until a specified type of background activity completes. Currently, this subcommand can wait for any of the following: - Scrubs or resilvers to complete - Devices to initialized - Devices to be replaced - Devices to be removed - Checkpoints to be discarded - Background freeing to complete For example, a scrub that is in progress could be waited for by running zpool wait -t scrub <pool> This also adds a -w flag to the attach, checkpoint, initialize, replace, remove, and scrub subcommands. When used, this flag makes the operations kicked off by these subcommands synchronous instead of asynchronous. This functionality is implemented using a new ioctl. The type of activity to wait for is provided as input to the ioctl, and the ioctl blocks until all activity of that type has completed. An ioctl was used over other methods of kernel-userspace communiction primarily for the sake of portability. Porting Notes: This is ported from Delphix OS change DLPX-44432. The following changes were made while porting: - Added ZoL-style ioctl input declaration. - Reorganized error handling in zpool_initialize in libzfs to integrate better with changes made for TRIM support. - Fixed check for whether a checkpoint discard is in progress. Previously it also waited if the pool had a checkpoint, instead of just if a checkpoint was being discarded. - Exposed zfs_initialize_chunk_size as a ZoL-style tunable. - Updated more existing tests to make use of new 'zpool wait' functionality, tests that don't exist in Delphix OS. - Used existing ZoL tunable zfs_scan_suspend_progress, together with zinject, in place of a new tunable zfs_scan_max_blks_per_txg. - Added support for a non-integral interval argument to zpool wait. Future work: ZoL has support for trimming devices, which Delphix OS does not. In the future, 'zpool wait' could be extended to add the ability to wait for trim operations to complete. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: John Kennedy <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: John Gallagher <[email protected]> Closes #9162
* Fix typos in man/Andrea Gelmini2019-08-308-16/+16
| | | | | | | Reviewed-by: Ryan Moeller <[email protected]> Reviewed-by: Richard Laager <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Andrea Gelmini <[email protected]> Closes #9233
* Keep more metaslabs loadedPaul Dagnelie2019-08-291-1/+29
| | | | | | | | | | | | | | | | | | | | | | | | With the other metaslab changes loaded onto a system, we can significantly reduce the memory usage of each loaded metaslab and unload them on demand if there is memory pressure. However, none of those changes actually result in us keeping more metaslabs loaded. If we don't keep more metaslabs loaded, we will still have to wait for demand-loading to finish when no loaded metaslab can satisfy our allocation, which can cause ZIL performance issues. In addition, performance is traditionally measured by IOs per unit time, while unloading is currently done on a txg-count basis. Txgs can take a widely varying range of times, from tenths of a second to several seconds. This can result in confusing, hard to predict behavior. This change simply adds a time-based component to metaslab unloading. A metaslab will remain loaded for one minute and 8 txgs (by default) after it was last used, unless it is evicted due to memory pressure. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> External-issue: DLPX-65016 External-issue: DLPX-65047 Closes #9197
* Cap metaslab memory usagePaul Dagnelie2019-08-161-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | On systems with large amounts of storage and high fragmentation, a huge amount of space can be used by storing metaslab range trees. Since metaslabs are only unloaded during a txg sync, and only if they have been inactive for 8 txgs, it is possible to get into a state where all of the system's memory is consumed by range trees and metaslabs, and txgs cannot sync. While ZFS knows how to evict ARC data when needed, it has no such mechanism for range tree data. This can result in boot hangs for some system configurations. First, we add the ability to unload metaslabs outside of syncing context. Second, we store a multilist of all loaded metaslabs, sorted by their selection txg, so we can quickly identify the oldest metaslabs. We use a multilist to reduce lock contention during heavy write workloads. Finally, we add logic that will unload a metaslab when we're loading a new metaslab, if we're using more than a certain fraction of the available memory on range trees. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Sebastien Roy <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Closes #9128
* spa_load_verify() may consume too much memoryGeorge Wilson2019-08-131-4/+4
| | | | | | | | | | | | | | | | | | | | When a pool is imported it will scan the pool to verify the integrity of the data and metadata. The amount it scans will depend on the import flags provided. On systems with small amounts of memory or when importing a pool from the crash kernel, it's possible for spa_load_verify to issue too many I/Os that it consumes all the memory of the system resulting in an OOM message or a hang. To prevent this, we limit the amount of memory that the initial pool scan can consume. This change will, by default, use 1/16th of the ARC for scan I/Os to prevent running the system out of memory during import. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Signed-off-by: George Wilson [email protected] External-issue: DLPX-65237 External-issue: DLPX-65238 Closes #9146
* Introduce getting holds and listing bookmarks through ZCPSerapheim Dimitropoulos2019-08-121-1/+27
| | | | | | | | | | | | | | | | Consumers of ZFS Channel Programs can now list bookmarks, and get holds from datasets. A minor-refactoring was also applied to distinguish between user and system properties in ZCP. Reviewed-by: Paul Dagnelie <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Ported-by: Serapheim Dimitropoulos <[email protected]> Signed-off-by: Dan Kimmel <[email protected]> OpenZFS-issue: https://illumos.org/issues/8862 Closes #7902
* Metaslab max_size should be persisted while unloadedPaul Dagnelie2019-08-051-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | When we unload metaslabs today in ZFS, the cached max_size value is discarded. We instead use the histogram to determine whether or not we think we can satisfy an allocation from the metaslab. This can result in situations where, if we're doing I/Os of a size not aligned to a histogram bucket, a metaslab is loaded even though it cannot satisfy the allocation we think it can. For example, a metaslab with 16 entries in the 16k-32k bucket may have entirely 16kB entries. If we try to allocate a 24kB buffer, we will load that metaslab because we think it should be able to handle the allocation. Doing so is expensive in CPU time, disk reads, and average IO latency. This is exacerbated if the write being attempted is a sync write. This change makes ZFS cache the max_size after the metaslab is unloaded. If we ever get a free (or a coalesced group of frees) larger than the max_size, we will update it. Otherwise, we leave it as is. When attempting to allocate, we use the max_size as a lower bound, and respect it unless we are in try_hard. However, we do age the max_size out at some point, since we expect the actual max_size to increase as we do more frees. A more sophisticated algorithm here might be helpful, but this works reasonably well. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Closes #9055
* List log_spacemap feature in zpool-features.5 manualSerapheim Dimitropoulos2019-07-311-0/+22
| | | | | | | | | Update zpool-features.5 manpage to describe the log_spacemap feature. Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Pavel Zakharov <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #9096
* Fast Clone DeletionSara Hartse2019-07-262-1/+112
| | | | | | | | | | | | | | | | | | | | | Deleting a clone requires finding blocks are clone-only, not shared with the snapshot. This was done by traversing the entire block tree which results in a large performance penalty for sparsely written clones. This is new method keeps track of clone blocks when they are modified in a "Livelist" so that, when it’s time to delete, the clone-specific blocks are already at hand. We see performance improvements because now deletion work is proportional to the number of clone-modified blocks, not the size of the original dataset. Reviewed-by: Sean Eric Fagan <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Signed-off-by: Sara Hartse <[email protected]> Closes #8416
* New service that waits on zvol links to be createdPavel Zakharov2019-07-172-1/+22
| | | | | | | | | | | | | | | | The zfs-volume-wait.service scans existing zvols and waits for their links under /dev to be created. Any service that depends on zvol links to be there should add a dependency on zfs-volumes.target. By default, this target is not enabled. Reviewed-by: Fabian Grünbichler <[email protected]> Reviewed-by: Antonio Russo <[email protected]> Reviewed-by: Richard Laager <[email protected]> Reviewed-by: loli10K <[email protected]> Reviewed-by: John Gallagher <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Pavel Zakharov <[email protected]> Closes #8975
* Add zfs create dryrunMike Gerdts2019-07-161-5/+93
| | | | | | | | | | | | | | | | | | | Adds the ability to sanity check zfs create arguments and to see the value of any additional properties that will local to the dataset. For example, automation that may need to adjust quota on a parent filesystem before creating a volume may call `zfs create -nP -V <size> <volume>` to obtain the value of refreservation. This adds the following options to zfs create: - -n dry-run (no-op) - -v verbose - -P parseable (implies verbose) Reviewed-by: Ryan Moeller <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Jerry Jelinek <[email protected]> Signed-off-by: Mike Gerdts <[email protected]> Closes #8974
* Log Spacemap ProjectSerapheim Dimitropoulos2019-07-162-1/+149
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | = Motivation At Delphix we've seen a lot of customer systems where fragmentation is over 75% and random writes take a performance hit because a lot of time is spend on I/Os that update on-disk space accounting metadata. Specifically, we seen cases where 20% to 40% of sync time is spend after sync pass 1 and ~30% of the I/Os on the system is spent updating spacemaps. The problem is that these pools have existed long enough that we've touched almost every metaslab at least once, and random writes scatter frees across all metaslabs every TXG, thus appending to their spacemaps and resulting in many I/Os. To give an example, assuming that every VDEV has 200 metaslabs and our writes fit within a single spacemap block (generally 4K) we have 200 I/Os. Then if we assume 2 levels of indirection, we need 400 additional I/Os and since we are talking about metadata for which we keep 2 extra copies for redundancy we need to triple that number, leading to a total of 1800 I/Os per VDEV every TXG. We could try and decrease the number of metaslabs so we have less I/Os per TXG but then each metaslab would cover a wider range on disk and thus would take more time to be loaded in memory from disk. In addition, after it's loaded, it's range tree would consume more memory. Another idea would be to just increase the spacemap block size which would allow us to fit more entries within an I/O block resulting in fewer I/Os per metaslab and a speedup in loading time. The problem is still that we don't deal with the number of I/Os going up as the number of metaslabs is increasing and the fact is that we generally write a lot to a few metaslabs and a little to the rest of them. Thus, just increasing the block size would actually waste bandwidth because we won't be utilizing our bigger block size. = About this patch This patch introduces the Log Spacemap project which provides the solution to the above problem while taking into account all the aforementioned tradeoffs. The details on how it achieves that can be found in the references sections below and in the code (see Big Theory Statement in spa_log_spacemap.c). Even though the change is fairly constraint within the metaslab and lower-level SPA codepaths, there is a side-change that is user-facing. The change is that VDEV IDs from VDEV holes will no longer be reused. To give some background and reasoning for this, when a log device is removed and its VDEV structure was replaced with a hole (or was compacted; if at the end of the vdev array), its vdev_id could be reused by devices added after that. Now with the pool-wide space maps recording the vdev ID, this behavior can cause problems (e.g. is this entry referring to a segment in the new vdev or the removed log?). Thus, to simplify things the ID reuse behavior is gone and now vdev IDs for top-level vdevs are truly unique within a pool. = Testing The illumos implementation of this feature has been used internally for a year and has been in production for ~6 months. For this patch specifically there don't seem to be any regressions introduced to ZTS and I have been running zloop for a week without any related problems. = Performance Analysis (Linux Specific) All performance results and analysis for illumos can be found in the links of the references. Redoing the same experiments in Linux gave similar results. Below are the specifics of the Linux run. After the pool reached stable state the percentage of the time spent in pass 1 per TXG was 64% on average for the stock bits while the log spacemap bits stayed at 95% during the experiment (graph: sdimitro.github.io/img/linux-lsm/PercOfSyncInPassOne.png). Sync times per TXG were 37.6 seconds on average for the stock bits and 22.7 seconds for the log spacemap bits (related graph: sdimitro.github.io/img/linux-lsm/SyncTimePerTXG.png). As a result the log spacemap bits were able to push more TXGs, which is also the reason why all graphs quantified per TXG have more entries for the log spacemap bits. Another interesting aspect in terms of txg syncs is that the stock bits had 22% of their TXGs reach sync pass 7, 55% reach sync pass 8, and 20% reach 9. The log space map bits reached sync pass 4 in 79% of their TXGs, sync pass 7 in 19%, and sync pass 8 at 1%. This emphasizes the fact that not only we spend less time on metadata but we also iterate less times to convergence in spa_sync() dirtying objects. [related graphs: stock- sdimitro.github.io/img/linux-lsm/NumberOfPassesPerTXGStock.png lsm- sdimitro.github.io/img/linux-lsm/NumberOfPassesPerTXGLSM.png] Finally, the improvement in IOPs that the userland gains from the change is approximately 40%. There is a consistent win in IOPS as you can see from the graphs below but the absolute amount of improvement that the log spacemap gives varies within each minute interval. sdimitro.github.io/img/linux-lsm/StockVsLog3Days.png sdimitro.github.io/img/linux-lsm/StockVsLog10Hours.png = Porting to Other Platforms For people that want to port this commit to other platforms below is a list of ZoL commits that this patch depends on: Make zdb results for checkpoint tests consistent db587941c5ff6dea01932bb78f70db63cf7f38ba Update vdev_is_spacemap_addressable() for new spacemap encoding 419ba5914552c6185afbe1dd17b3ed4b0d526547 Simplify spa_sync by breaking it up to smaller functions 8dc2197b7b1e4d7ebc1420ea30e51c6541f1d834 Factor metaslab_load_wait() in metaslab_load() b194fab0fb6caad18711abccaff3c69ad8b3f6d3 Rename range_tree_verify to range_tree_verify_not_present df72b8bebe0ebac0b20e0750984bad182cb6564a Change target size of metaslabs from 256GB to 16GB c853f382db731e15a87512f4ef1101d14d778a55 zdb -L should skip leak detection altogether 21e7cf5da89f55ce98ec1115726b150e19eefe89 vs_alloc can underflow in L2ARC vdevs 7558997d2f808368867ca7e5234e5793446e8f3f Simplify log vdev removal code 6c926f426a26ffb6d7d8e563e33fc176164175cb Get rid of space_map_update() for ms_synced_length 425d3237ee88abc53d8522a7139c926d278b4b7f Introduce auxiliary metaslab histograms 928e8ad47d3478a3d5d01f0dd6ae74a9371af65e Error path in metaslab_load_impl() forgets to drop ms_sync_lock 8eef997679ba54547f7d361553d21b3291f41ae7 = References Background, Motivation, and Internals of the Feature - OpenZFS 2017 Presentation: youtu.be/jj2IxRkl5bQ - Slides: slideshare.net/SerapheimNikolaosDim/zfs-log-spacemaps-project Flushing Algorithm Internals & Performance Results (Illumos Specific) - Blogpost: sdimitro.github.io/post/zfs-lsm-flushing/ - OpenZFS 2018 Presentation: youtu.be/x6D2dHRjkxw - Slides: slideshare.net/SerapheimNikolaosDim/zfs-log-spacemap-flushing-algorithm Upstream Delphix Issues: DLPX-51539, DLPX-59659, DLPX-57783, DLPX-61438, DLPX-41227, DLPX-59320 DLPX-63385 Reviewed-by: Sean Eric Fagan <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8442
* systemd encryption key supportAntonio Russo2019-07-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | Modify zfs-mount-generator to produce a dependency on new zfs-import-key-*.service units, dynamically created at boot to call zfs load-key for the encryption root, before attempting to mount any encrypted datasets. These units are created by zfs-mount-generator, and RequiresMountsFor on the keyfile, if present, or call systemd-ask-password if a passphrase is requested. This patch includes suggestions from @Fabian-Gruenbichler, @ryanjaeb and @rlaager, as well an adaptation of @rlaager's script to retry on incorrect password entry. Reviewed-by: Richard Laager <[email protected]> Reviewed-by: Fabian Grünbichler <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Antonio Russo <[email protected]> Closes #8750 Closes #8848
* Fix zfs "redact" misc issuesloli10K2019-07-051-2/+2
| | | | | | | | | | | * zfs redact error messages do not end with newline character * 30af21b0 inadvertently removed some ZFS_PROP comments * man/zfs: zfs redact <redaction_snapshot> is not optional Reviewed-by: Giuseppe Di Natale <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: George Melikov <[email protected]> Signed-off-by: loli10K <[email protected]> Closes #8988
* Fix typo in zpool-features.5, section bookmark_writtenMatthew Ahrens2019-07-031-1/+1
| | | | | | | | | | The full property name includes "delphix", not "delphxi". Reviewed-by: Richard Laager <[email protected]> Reviewed-by: George Melikov <[email protected]> Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> Closes #8985
* Fix zfs(8) mandoc errorsloli10K2019-07-021-1/+0
| | | | | | | | | | | | | | This was accidentally introduced in 765d1f06: mandoc: ./man/man8/zfs.8: ERROR: skipping item outside list: It Ar filesystem Ns | Ns Ar mountpoint mandoc: ./man/man8/zfs.8: ERROR: skipping item outside list: It Xo mandoc: ./man/man8/zfs.8: ERROR: skipping end of block that is not open: Xc mandoc: ./man/man8/zfs.8: ERROR: skipping item outside list: It Xo mandoc: ./man/man8/zfs.8: ERROR: skipping end of block that is not open: Xc Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: George Melikov <[email protected]> Signed-off-by: loli10K <[email protected]> Closes #8980
* Add 'zfs umount -u' for encrypted datasetsTom Caputi2019-06-281-5/+8
| | | | | | | | | | | This patch adds the ability for the user to unload keys for datasets as they are being unmounted. This is analogous to 'zfs mount -l'. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Alek Pinchuk <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes: #8917 Closes: #8952
* Remove dedupditto functionalityMatthew Ahrens2019-06-191-11/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If dedup is in use, the `dedupditto` property can be set, causing ZFS to keep an extra copy of data that is referenced many times (>100x). The idea was that this data is more important than other data and thus we want to be really sure that it is not lost if the disk experiences a small amount of random corruption. ZFS (and system administrators) rely on the pool-level redundancy to protect their data (e.g. mirroring or RAIDZ). Since the user/sysadmin doesn't have control over what data will be offered extra redundancy by dedupditto, this extra redundancy is not very useful. The bulk of the data is still vulnerable to loss based on the pool-level redundancy. For example, if particle strikes corrupt 0.1% of blocks, you will either be saved by mirror/raidz, or you will be sad. This is true even if dedupditto saved another 0.01% of blocks from being corrupted. Therefore, the dedupditto functionality is rarely enabled (i.e. the property is rarely set), and it fulfills its promise of increased redundancy even more rarely. Additionally, this feature does not work as advertised (on existing releases), because scrub/resilver did not repair the extra (dedupditto) copy (see https://github.com/zfsonlinux/zfs/pull/8270). In summary, this seldom-used feature doesn't work, and even if it did it wouldn't provide useful data protection. It has a non-trivial maintenance burden (again see https://github.com/zfsonlinux/zfs/pull/8270). We should remove the dedupditto functionality. For backwards compatibility with the existing CLI, "zpool set dedupditto" will still "succeed" (exit code zero), but won't have any effect. For backwards compatibility with existing pools that had dedupditto enabled at some point, the code will still be able to understand dedupditto blocks and free them when appropriate. However, ZFS won't write any new dedupditto blocks. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: Alek Pinchuk <[email protected]> Issue #8270 Closes #8310
* Implement Redacted Send/ReceivePaul Dagnelie2019-06-193-8/+340
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Redacted send/receive allows users to send subsets of their data to a target system. One possible use case for this feature is to not transmit sensitive information to a data warehousing, test/dev, or analytics environment. Another is to save space by not replicating unimportant data within a given dataset, for example in backup tools like zrepl. Redacted send/receive is a three-stage process. First, a clone (or clones) is made of the snapshot to be sent to the target. In this clone (or clones), all unnecessary or unwanted data is removed or modified. This clone is then snapshotted to create the "redaction snapshot" (or snapshots). Second, the new zfs redact command is used to create a redaction bookmark. The redaction bookmark stores the list of blocks in a snapshot that were modified by the redaction snapshot(s). Finally, the redaction bookmark is passed as a parameter to zfs send. When sending to the snapshot that was redacted, the redaction bookmark is used to filter out blocks that contain sensitive or unwanted information, and those blocks are not included in the send stream. When sending from the redaction bookmark, the blocks it contains are considered as candidate blocks in addition to those blocks in the destination snapshot that were modified since the creation_txg of the redaction bookmark. This step is necessary to allow the target to rehydrate data in the case where some blocks are accidentally or unnecessarily modified in the redaction snapshot. The changes to bookmarks to enable fast space estimation involve adding deadlists to bookmarks. There is also logic to manage the life cycles of these deadlists. The new size estimation process operates in cases where previously an accurate estimate could not be provided. In those cases, a send is performed where no data blocks are read, reducing the runtime significantly and providing a byte-accurate size estimate. Reviewed-by: Dan Kimmel <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Prashanth Sreenivasa <[email protected]> Reviewed-by: John Kennedy <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Chris Williamson <[email protected]> Reviewed-by: Pavel Zhakarov <[email protected]> Reviewed-by: Sebastien Roy <[email protected]> Reviewed-by: Prakash Surya <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Closes #7958
* panic in removal_remap test on 4K devicesMatthew Ahrens2019-06-131-0/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the zfs_remove_max_segment tunable is changed to be not a multiple of the sector size, then the device removal code will malfunction and try to create mappings that are smaller than one sector, leading to a panic. On debug bits this assertion will fail in spa_vdev_copy_segment(): ASSERT3U(DVA_GET_ASIZE(&dst), ==, size); On nondebug, the system panics with a stack like: metaslab_free_concrete() metaslab_free_impl() metaslab_free_impl_cb() vdev_indirect_remap() free_from_removing_vdev() metaslab_free_impl() metaslab_free_dva() metaslab_free() Fortunately, the default for zfs_remove_max_segment is 1MB, so this can't occur by default. We hit it during this test because removal_remap.ksh changes zfs_remove_max_segment to 1KB. When testing on 4KB-sector disks, we hit the bug. This change makes the zfs_remove_max_segment tunable more robust, automatically rounding it up to a multiple of the sector size. We also turn some key assertions into VERIFY's so that similar bugs would be caught before they are encoded on disk (and thus avoid a panic-reboot-loop). Reviewed-by: Sean Eric Fagan <[email protected]> Reviewed-by: Pavel Zakharov <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Sebastien Roy <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> External-issue: DLPX-61342 Closes #8893
* compress metadata in later sync passesMatthew Ahrens2019-06-131-2/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Starting in sync pass 5 (zfs_sync_pass_dont_compress), we disable compression (including of metadata). Ostensibly this helps the sync passes to converge (i.e. for a sync pass to not need to allocate anything because it is 100% overwrites). However, in practice it increases the average number of sync passes, because when we turn compression off, a lot of block's size will change and thus we have to re-allocate (not overwrite) them. It also increases the number of 128KB allocations (e.g. for indirect blocks and spacemaps) because these will not be compressed. The 128K allocations are especially detrimental to performance on highly fragmented systems, which may have very few free segments of this size, and may need to load new metaslabs to satisfy 128K allocations. We should increase zfs_sync_pass_dont_compress. In practice on a highly fragmented system we see a few 5-pass txg's, a tiny number of 6-pass txg's, and no txg's with more than 6 passes. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Richard Elling <[email protected]> Reviewed by: Pavel Zakharov <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: George Wilson <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> External-issue: DLPX-63431 Closes #8892
* looping in metaslab_block_picker impacts performance on fragmented poolsMatthew Ahrens2019-06-131-0/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On fragmented pools with high-performance storage, the looping in metaslab_block_picker() can become the performance-limiting bottleneck. When looking for a larger block (e.g. a 128K block for the ZIL), we may search through many free segments (up to hundreds of thousands) to find one that is large enough to satisfy the allocation. This can take a long time (up to dozens of ms), and is done while holding the ms_lock, which other threads may spin waiting for. When this performance problem is encountered, profiling will show high CPU time in metaslab_block_picker, as well as in mutex_enter from various callers. The problem is very evident on a test system with a sync write workload with 8K writes to a recordsize=8k filesystem, with 4TB of SSD storage, 84% full and 88% fragmented. It has also been observed on production systems with 90TB of storage, 76% full and 87% fragmented. The fix is to change metaslab_df_alloc() to search only up to 16MB from the previous allocation (of this alignment). After that, we will pick a segment that is of the exact size requested (or larger). This reduces the number of iterations to a few hundred on fragmented pools (a ~100x improvement). Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Paul Dagnelie <[email protected]> Reviewed-by: Tony Nguyen <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> External-issue: DLPX-62324 Closes #8877
* fat zap should prefetch when iteratingMatthew Ahrens2019-06-121-0/+25
| | | | | | | | | | | | | | | | | When iterating over a ZAP object, we're almost always certain to iterate over the entire object. If there are multiple leaf blocks, we can realize a performance win by issuing reads for all the leaf blocks in parallel when the iteration begins. For example, if we have 10,000 snapshots, "zfs destroy -nv pool/fs@1%9999" can take 30 minutes when the cache is cold. This change provides a >3x performance improvement, by issuing the reads for all ~64 blocks of each ZAP object in parallel. Reviewed-by: Andreas Dilger <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> External-issue: DLPX-58347 Closes #8862
* make zil max block size tunableMatthew Ahrens2019-06-101-0/+12
| | | | | | | | | | | | | | | | | | | | | | | We've observed that on some highly fragmented pools, most metaslab allocations are small (~2-8KB), but there are some large, 128K allocations. The large allocations are for ZIL blocks. If there is a lot of fragmentation, the large allocations can be hard to satisfy. The most common impact of this is that we need to check (and thus load) lots of metaslabs from the ZIL allocation code path, causing sync writes to wait for metaslabs to load, which can take a second or more. In the worst case, we may not be able to satisfy the allocation, in which case the ZIL will resort to txg_wait_synced() to ensure the change is on disk. To provide a workaround for this, this change adds a tunable that can reduce the size of ZIL blocks. External-issue: DLPX-61719 Reviewed-by: George Wilson <[email protected]> Reviewed-by: Paul Dagnelie <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> Closes #8865
* Reduced IOPS when all vdevs are in the zfs_mg_fragmentation_thresholdSerapheim Dimitropoulos2019-06-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | Historically while doing performance testing we've noticed that IOPS can be significantly reduced when all vdevs in the pool are hitting the zfs_mg_fragmentation_threshold percentage. Specifically in a hypothetical pool with two vdevs, what can happen is the following: Vdev A would go above that threshold and only vdev B would be used. Then vdev B would pass that threshold but vdev A would go below it (we've been freeing from A to allocate to B). The allocations would go back and forth utilizing one vdev at a time with IOPS taking a hit. Empirically, we've seen that our vdev selection for allocations is good enough that fragmentation increases uniformly across all vdevs the majority of the time. Thus we set the threshold percentage high enough to avoid hitting the speed bump on pools that are being pushed to the edge. We effectively disable its effect in the majority of the cases but we don't remove (at least for now) just in case we hit any weird behavior in the future. Reviewed-by: George Melikov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8859
* Fixed a small typo in man/man1/raidz_test.1Peter Wirdemo2019-06-051-1/+1
| | | | | | | Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: George Melikov <[email protected]> Reviewed-by: Chris Dunlop <[email protected]> Signed-off-by: Peter Wirdemo <[email protected]> Closes #8855
* Correct man page datesRichard Laager2019-05-085-5/+5
| | | | | | | | | | | Various changes (many by me) have been made to the man pages without bumping their dates. I have now corrected them based on the last commit to each file. I also added the script I used to make these changes. Reviewed-by: Olaf Faaland <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Richard Laager <[email protected]> Closes #8710
* Make zfs_special_class_metadata_reserve_pct into a parameterDeHackEd2019-05-071-0/+14
| | | | | | | | Exported and documented a new module parameter. Reviewed-by: Richard Laager <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: DHE <[email protected]> Closes #8706
* Fix send/recv lost spill blockBrian Behlendorf2019-05-071-1/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When receiving a DRR_OBJECT record the receive_object() function needs to determine how to handle a spill block associated with the object. It may need to be removed or kept depending on how the object was modified at the source. This determination is currently accomplished using a heuristic which takes in to account the DRR_OBJECT record and the existing object properties. This is a problem because there isn't quite enough information available to do the right thing under all circumstances. For example, when only the block size changes the spill block is removed when it should be kept. What's needed to resolve this is an additional flag in the DRR_OBJECT which indicates if the object being received references a spill block. The DRR_OBJECT_SPILL flag was added for this purpose. When set then the object references a spill block and it must be kept. Either it is update to date, or it will be replaced by a subsequent DRR_SPILL record. Conversely, if the object being received doesn't reference a spill block then any existing spill block should always be removed. Since previous versions of ZFS do not understand this new flag additional DRR_SPILL records will be inserted in to the stream. This has the advantage of being fully backward compatible. Existing ZFS systems receiving this stream will recreate the spill block if it was incorrectly removed. Updated ZFS versions will correctly ignore the additional spill blocks which can be identified by checking for the DRR_SPILL_UNMODIFIED flag. The small downside to this approach is that is may increase the size of the stream and of the received snapshot on previous versions of ZFS. Additionally, when receiving streams generated by previous unpatched versions of ZFS spill blocks may still be lost. OpenZFS-issue: https://www.illumos.org/issues/9952 FreeBSD-issue: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=233277 Reviewed-by: Paul Dagnelie <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Tom Caputi <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #8668
* Cleanup special/dedup languageRichard Laager2019-05-071-6/+6
| | | | | | | | | | | | | This standardizes the language on "deduplication tables" rather than "dedup data" (which might be read as the data blocks rather than the DDT). Likewise, it standardizes on "small file blocks". It also standardizes on "normal" rather than using both "normal" and "general" in the same paragraph. I also replaced "non-specified" with the more explicit "non-dedup/special". Reviewed-by: George Melikov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Richard Laager <[email protected]> Closes #8713
* OpenZFS 10473 - zfs(1M) missing cross-reference to zfs-program(1M)Richard Laager2019-05-061-1/+2
| | | | | | | | | | | | | | | Authored by: Jason King <[email protected]> Reviewed by: Toomas Soome <[email protected]> Reviewed by: Andy Fiddaman <[email protected]> Reviewed by: Peter Tribble <[email protected]> Reviewed by: Gergő Mihály Doma <[email protected]> Reviewed-by: George Melikov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Approved by: Dan McDonald <[email protected]> Ported-by: Richard Laager <[email protected]> OpenZFS-issue: https://www.illumos.org/issues/10473 OpenZFS-commit: https://github.com/illumos/illumos-gate/commit/736e67003 Closes #8711
* Add feature check for 'zpool resilver' commandTom Caputi2019-05-021-1/+3
| | | | | | | | | | | | The 'zpool resilver' command requires that the resilver_defer feature is active on the pool. Unfortunately, the check for this was left out of the original patch. This commit simply corrects this so that the command properly returns an error in this case. Reviewed by: Brian Behlendorf <[email protected]> Reviewed-by: Igor Kozhukhov <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #8700
* Fix estimated scrub completion timeTom Caputi2019-05-011-0/+4
| | | | | | | | | | | | | | | | | | | Currently, it is possible for the 'zpool scrub' command to progress slightly beyond 100% due to concurrent changes happening on the live pool. This behavior is expected, but the userspace code for 'zpool status' would subtract the expected amount of data from the amount of data already scrubbed, resulting in a negative integer being casted to a large positive one. This number was then used to calculate the estimated completion time, resulting in wildly wrong results. This code changes the behavior so that 'zpool status' does not attempt to report an estimate during this period. Reviewed by: Brian Behlendorf <[email protected]> Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: George Melikov <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #8611 Closes #8687
* Clarify that deduped data is encryptedRichard Laager2019-04-301-1/+2
| | | | | | | Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: George Melikov <[email protected]> Reviewed-by: Tom Caputi <[email protected]> Signed-off-by: Richard Laager <[email protected]> Closes #8691
* Clarify and improve encryption documentationRichard Laager2019-04-241-13/+14
| | | | | | | | | | | | | | | | | - Remove the language that "all user data" is encrypted. This is to avoid misunderstandings or arguments about what is "user data", especially in light of "user properties". - Document that properties are unencrypted. - Document that snapshot names are unencrypted. - For consistency with the rest of the zfs.8 man page, use "ZFS" as the generic noun, not (bolded) "zfs". The latter refers to the command. Likewise, use "ZFS" instead of "the kernel module". - Give "a passphrase" as an example of a "user's key". Reviewed-by: Tom Caputi <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: George Melikov <[email protected]> Signed-off-by: Richard Laager <[email protected]> Closes #8652
* Duplicate the encryption copies=3 limitationRichard Laager2019-04-241-0/+5
| | | | | | | | | This adds the encryption copies=3 limitation language into the copies property section. Reviewed-by: George Melikov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Richard Laager <[email protected]> Closes #8651
* Deprecate dedupdittoRichard Laager2019-04-241-0/+3
| | | | | | | | | | This documents, in zpool.8, that dedupditto is deprecated and will be made to have no effect in a future release. Reviewed-by: George Melikov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matthew Ahrens <[email protected]> Signed-off-by: Richard Laager <[email protected]> Closes #8650
* Eliminate useless double-bolding in man pagesRichard Laager2019-04-242-33/+33
| | | | | | | | | | As far as I know and can tell from testing, \fB\fB...\fR\fR is exactly equivalent to \fB...\fR. Reviewed-by: Tom Caputi <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Richard Laager <[email protected]> Closes #8641
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