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d592a99691
linux/drivers/md
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Shaohua Li d592a99691 raid5: add an option to avoid copy data from bio to stripe cache 
The stripe cache has two goals:
1. cache data, so next time if data can be found in stripe cache, disk access
can be avoided.
2. stable data. data is copied from bio to stripe cache and calculated parity.
data written to disk is from stripe cache, so if upper layer changes bio data,
data written to disk isn't impacted.

In my environment, I can guarantee 2 will not happen. And BDI_CAP_STABLE_WRITES
can guarantee 2 too. For 1, it's not common too. block plug mechanism will
dispatch a bunch of sequentail small requests together. And since I'm using
SSD, I'm using small chunk size. It's rare case stripe cache is really useful.

So I'd like to avoid the copy from bio to stripe cache and it's very helpful
for performance. In my 1M randwrite tests, avoid the copy can increase the
performance more than 30%.

Of course, this shouldn't be enabled by default. It's reported enabling
BDI_CAP_STABLE_WRITES can harm some workloads before, so I added an option to
control it.

Neilb:
  changed BUG_ON to WARN_ON
  Removed some assignments from raid5_build_block which are now not needed.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2014-05-29 16:59:47 +10:00
..
bcache bcache: remove nested function usage 2014-03-18 12:39:28 -07:00
persistent-data dm transaction manager: fix corruption due to non-atomic transaction commit 2014-03-27 16:56:23 -04:00
bitmap.c md/bitmap: remove confusing code from filemap_get_page. 2014-05-29 16:59:47 +10:00
bitmap.h kernfs: s/sysfs_dirent/kernfs_node/ and rename its friends accordingly 2013-12-11 15:28:36 -08:00
dm-bio-prison.c dm: add cache target 2013-03-01 22:45:51 +00:00
dm-bio-prison.h dm: add cache target 2013-03-01 22:45:51 +00:00
dm-bio-record.h dm: Refactor for new bio cloning/splitting 2013-11-23 22:33:55 -08:00
dm-bufio.c Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block 2014-01-30 11:19:05 -08:00
dm-bufio.h dm snapshot: use dm-bufio prefetch 2014-01-14 23:23:03 -05:00
dm-builtin.c dm sysfs: fix a module unload race 2014-01-14 23:23:04 -05:00
dm-cache-block-types.h dm cache: remove remainder of distinct discard block size 2014-03-27 16:56:23 -04:00
dm-cache-metadata.c dm cache: fix a lock-inversion 2014-04-04 14:53:05 -04:00
dm-cache-metadata.h dm cache: fix a lock-inversion 2014-04-04 14:53:05 -04:00
dm-cache-policy-cleaner.c dm cache: policy change version from string to integer set 2013-03-20 17:21:27 +00:00
dm-cache-policy-internal.h dm cache: add remove_cblock method to policy interface 2013-11-11 11:37:50 -05:00
dm-cache-policy-mq.c dm cache mq: fix memory allocation failure for large cache devices 2014-02-28 12:18:29 -05:00
dm-cache-policy.c dm cache: add policy name to status output 2014-01-16 13:44:11 -05:00
dm-cache-policy.h dm cache: add policy name to status output 2014-01-16 13:44:11 -05:00
dm-cache-target.c dm cache: fix writethrough mode quiescing in cache_map 2014-05-01 16:14:24 -04:00
dm-crypt.c dm crypt: fix cpu hotplug crash by removing per-cpu structure 2014-05-14 16:11:35 -04:00
dm-delay.c Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block 2014-01-30 11:19:05 -08:00
dm-era-target.c dm: take care to copy the space map roots before locking the superblock 2014-03-27 16:56:23 -04:00
dm-exception-store.c dm: replace simple_strtoul 2012-07-27 15:07:59 +01:00
dm-exception-store.h
dm-flakey.c block: Abstract out bvec iterator 2013-11-23 22:33:47 -08:00
dm-io.c dm io: fix I/O to multiple destinations 2014-02-17 11:00:05 -05:00
dm-ioctl.c dm: allow remove to be deferred 2013-11-09 18:20:22 -05:00
dm-kcopyd.c dm: stop using WQ_NON_REENTRANT 2013-08-23 09:02:13 -04:00
dm-linear.c block: Abstract out bvec iterator 2013-11-23 22:33:47 -08:00
dm-log-userspace-base.c dm log userspace: allow mark requests to piggyback on flush requests 2014-01-21 23:46:27 -05:00
dm-log-userspace-transfer.c connector: add portid to unicast in addition to broadcasting 2014-02-07 15:40:17 -08:00
dm-log-userspace-transfer.h
dm-log.c dm: use memweight() 2012-07-30 17:25:16 -07:00
dm-mpath.c dm mpath: fix lock order inconsistency in multipath_ioctl 2014-05-14 16:12:17 -04:00
dm-mpath.h
dm-path-selector.c
dm-path-selector.h
dm-queue-length.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-raid1.c dm raid1: fix immutable biovec related BUG when retrying read bio 2014-02-18 10:48:57 -05:00
dm-raid.c MD: Remember the last sync operation that was performed 2013-06-26 12:38:24 +10:00
dm-region-hash.c block: Abstract out bvec iterator 2013-11-23 22:33:47 -08:00
dm-round-robin.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-service-time.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-snap-persistent.c dm snapshot: fix metadata corruption 2014-03-03 17:58:13 -05:00
dm-snap-transient.c md: Add in export.h for files using EXPORT_SYMBOL 2011-10-31 19:31:19 -04:00
dm-snap.c Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block 2014-01-30 11:19:05 -08:00
dm-stats.c dm stats: initialize read-only module parameter 2013-12-10 19:13:21 -05:00
dm-stats.h dm: add statistics support 2013-09-05 20:46:06 -04:00
dm-stripe.c block: Abstract out bvec iterator 2013-11-23 22:33:47 -08:00
dm-switch.c block: Abstract out bvec iterator 2013-11-23 22:33:47 -08:00
dm-sysfs.c dm sysfs: fix a module unload race 2014-01-14 23:23:04 -05:00
dm-table.c dm table: add dm_table_run_md_queue_async 2014-03-27 16:56:24 -04:00
dm-target.c dm: allow error target to replace bio-based and request-based targets 2013-09-05 20:46:05 -04:00
dm-thin-metadata.c dm: take care to copy the space map roots before locking the superblock 2014-03-27 16:56:23 -04:00
dm-thin-metadata.h dm thin: ensure user takes action to validate data and metadata consistency 2014-03-05 15:25:35 -05:00
dm-thin.c dm thin: add timeout to stop out-of-data-space mode holding IO forever 2014-05-14 16:11:37 -04:00
dm-uevent.c md: Add in export.h for files using EXPORT_SYMBOL 2011-10-31 19:31:19 -04:00
dm-uevent.h
dm-verity.c dm verity: fix biovecs hash calculation regression 2014-04-15 12:19:24 -04:00
dm-zero.c dm: rename request variables to bios 2013-03-01 22:45:47 +00:00
dm.c dm table: add dm_table_run_md_queue_async 2014-03-27 16:56:24 -04:00
dm.h dm table: add dm_table_run_md_queue_async 2014-03-27 16:56:24 -04:00
faulty.c block: Abstract out bvec iterator 2013-11-23 22:33:47 -08:00
Kconfig dm: add era target 2014-03-27 16:56:23 -04:00
linear.c block: Introduce new bio_split() 2013-11-23 22:33:57 -08:00
linear.h
Makefile dm: add era target 2014-03-27 16:56:23 -04:00
md.c md: md_clear_badblocks should return an error code on failure. 2014-05-29 16:59:46 +10:00
md.h md/bitmap: don't abuse i_writecount for bitmap files. 2014-04-09 12:26:59 +10:00
multipath.c block: Abstract out bvec iterator 2013-11-23 22:33:47 -08:00
multipath.h
raid0.c block: Introduce new bio_split() 2013-11-23 22:33:57 -08:00
raid0.h md: add proper merge_bvec handling to RAID0 and Linear. 2012-03-19 12:46:39 +11:00
raid1.c md/raid1: r1buf_pool_alloc: free allocate pages when subsequent allocation fails. 2014-04-09 14:42:23 +10:00
raid1.h raid1: Rewrite the implementation of iobarrier. 2013-11-19 15:19:18 +11:00
raid5.c raid5: add an option to avoid copy data from bio to stripe cache 2014-05-29 16:59:47 +10:00
raid5.h raid5: add an option to avoid copy data from bio to stripe cache 2014-05-29 16:59:47 +10:00
raid10.c md/raid10: call wait_barrier() for each request submitted. 2014-05-06 09:49:26 +10:00
raid10.h MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 1) 2013-02-26 11:55:30 +11:00