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* dm cache: move hook_info into common portion of per_bio_data structureMike Snitzer2014-02-171-1/+1
| | | | | | | | | | | | | | | Commit c9d28d5d ("dm cache: promotion optimisation for writes") incorrectly placed the 'hook_info' member in the writethrough-only portion of the per_bio_data structure. Given that the overwrite optimization may be used for writeback the 'hook_info' member must be placed above the 'cache' member of the per_bio_data structure. Any members above 'cache' are available from both writeback and writethrough modes' per_bio_data structure. Signed-off-by: Mike Snitzer <[email protected]> Acked-by: Joe Thornber <[email protected]> Cc: [email protected] # 3.13+
* Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-blockLinus Torvalds2014-01-301-10/+18
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull core block IO changes from Jens Axboe: "The major piece in here is the immutable bio_ve series from Kent, the rest is fairly minor. It was supposed to go in last round, but various issues pushed it to this release instead. The pull request contains: - Various smaller blk-mq fixes from different folks. Nothing major here, just minor fixes and cleanups. - Fix for a memory leak in the error path in the block ioctl code from Christian Engelmayer. - Header export fix from CaiZhiyong. - Finally the immutable biovec changes from Kent Overstreet. This enables some nice future work on making arbitrarily sized bios possible, and splitting more efficient. Related fixes to immutable bio_vecs: - dm-cache immutable fixup from Mike Snitzer. - btrfs immutable fixup from Muthu Kumar. - bio-integrity fix from Nic Bellinger, which is also going to stable" * 'for-3.14/core' of git://git.kernel.dk/linux-block: (44 commits) xtensa: fixup simdisk driver to work with immutable bio_vecs block/blk-mq-cpu.c: use hotcpu_notifier() blk-mq: for_each_* macro correctness block: Fix memory leak in rw_copy_check_uvector() handling bio-integrity: Fix bio_integrity_verify segment start bug block: remove unrelated header files and export symbol blk-mq: uses page->list incorrectly blk-mq: use __smp_call_function_single directly btrfs: fix missing increment of bi_remaining Revert "block: Warn and free bio if bi_end_io is not set" block: Warn and free bio if bi_end_io is not set blk-mq: fix initializing request's start time block: blk-mq: don't export blk_mq_free_queue() block: blk-mq: make blk_sync_queue support mq block: blk-mq: support draining mq queue dm cache: increment bi_remaining when bi_end_io is restored block: fixup for generic bio chaining block: Really silence spurious compiler warnings block: Silence spurious compiler warnings block: Kill bio_pair_split() ...
| * Merge tag 'v3.13-rc6' into for-3.14/coreJens Axboe2013-12-311-1/+1
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Needed to bring blk-mq uptodate, since changes have been going in since for-3.14/core was established. Fixup merge issues related to the immutable biovec changes. Signed-off-by: Jens Axboe <[email protected]> Conflicts: block/blk-flush.c fs/btrfs/check-integrity.c fs/btrfs/extent_io.c fs/btrfs/scrub.c fs/logfs/dev_bdev.c
| * | dm cache: increment bi_remaining when bi_end_io is restoredMike Snitzer2013-12-041-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | Move the bio->bi_remaining increment into dm_unhook_bio() so the overwrite_endio() handler works as expected. Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
| * | block: Generic bio chainingKent Overstreet2013-11-241-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds a generic mechanism for chaining bio completions. This is going to be used for a bio_split() replacement, and it turns out to be very useful in a fair amount of driver code - a fair number of drivers were implementing this in their own roundabout ways, often painfully. Note that this means it's no longer to call bio_endio() more than once on the same bio! This can cause problems for drivers that save/restore bi_end_io. Arguably they shouldn't be saving/restoring bi_end_io at all - in all but the simplest cases they'd be better off just cloning the bio, and immutable biovecs is making bio cloning cheaper. But for now, we add a bio_endio_nodec() for these cases. Signed-off-by: Kent Overstreet <[email protected]> Cc: Jens Axboe <[email protected]>
| * | block: Abstract out bvec iteratorKent Overstreet2013-11-241-10/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Immutable biovecs are going to require an explicit iterator. To implement immutable bvecs, a later patch is going to add a bi_bvec_done member to this struct; for now, this patch effectively just renames things. Signed-off-by: Kent Overstreet <[email protected]> Cc: Jens Axboe <[email protected]> Cc: Geert Uytterhoeven <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: "Ed L. Cashin" <[email protected]> Cc: Nick Piggin <[email protected]> Cc: Lars Ellenberg <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Geoff Levand <[email protected]> Cc: Yehuda Sadeh <[email protected]> Cc: Sage Weil <[email protected]> Cc: Alex Elder <[email protected]> Cc: [email protected] Cc: Joshua Morris <[email protected]> Cc: Philip Kelleher <[email protected]> Cc: Rusty Russell <[email protected]> Cc: "Michael S. Tsirkin" <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Cc: Jeremy Fitzhardinge <[email protected]> Cc: Neil Brown <[email protected]> Cc: Alasdair Kergon <[email protected]> Cc: Mike Snitzer <[email protected]> Cc: [email protected] Cc: Martin Schwidefsky <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: [email protected] Cc: Boaz Harrosh <[email protected]> Cc: Benny Halevy <[email protected]> Cc: "James E.J. Bottomley" <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: "Nicholas A. Bellinger" <[email protected]> Cc: Alexander Viro <[email protected]> Cc: Chris Mason <[email protected]> Cc: "Theodore Ts'o" <[email protected]> Cc: Andreas Dilger <[email protected]> Cc: Jaegeuk Kim <[email protected]> Cc: Steven Whitehouse <[email protected]> Cc: Dave Kleikamp <[email protected]> Cc: Joern Engel <[email protected]> Cc: Prasad Joshi <[email protected]> Cc: Trond Myklebust <[email protected]> Cc: KONISHI Ryusuke <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Ben Myers <[email protected]> Cc: [email protected] Cc: Steven Rostedt <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Len Brown <[email protected]> Cc: Pavel Machek <[email protected]> Cc: "Rafael J. Wysocki" <[email protected]> Cc: Herton Ronaldo Krzesinski <[email protected]> Cc: Ben Hutchings <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Guo Chao <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Asai Thambi S P <[email protected]> Cc: Selvan Mani <[email protected]> Cc: Sam Bradshaw <[email protected]> Cc: Wei Yongjun <[email protected]> Cc: "Roger Pau Monné" <[email protected]> Cc: Jan Beulich <[email protected]> Cc: Stefano Stabellini <[email protected]> Cc: Ian Campbell <[email protected]> Cc: Sebastian Ott <[email protected]> Cc: Christian Borntraeger <[email protected]> Cc: Minchan Kim <[email protected]> Cc: Jiang Liu <[email protected]> Cc: Nitin Gupta <[email protected]> Cc: Jerome Marchand <[email protected]> Cc: Joe Perches <[email protected]> Cc: Peng Tao <[email protected]> Cc: Andy Adamson <[email protected]> Cc: fanchaoting <[email protected]> Cc: Jie Liu <[email protected]> Cc: Sunil Mushran <[email protected]> Cc: "Martin K. Petersen" <[email protected]> Cc: Namjae Jeon <[email protected]> Cc: Pankaj Kumar <[email protected]> Cc: Dan Magenheimer <[email protected]> Cc: Mel Gorman <[email protected]>6
* | | dm cache: add policy name to status outputMike Snitzer2014-01-161-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The cache's policy may have been established using the "default" alias, which is currently the "mq" policy but the default policy may change in the future. It is useful to know exactly which policy is being used. Add a 'real' member to the dm_cache_policy_type structure and have the "default" dm_cache_policy_type point to the real "mq" dm_cache_policy_type. Update dm_cache_policy_get_name() to check if real is set, if so report the name of the real policy (not the alias). Requested-by: Jonathan Brassow <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* | | dm cache: add block sizes and total cache blocks to status outputMike Snitzer2014-01-101-6/+10
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Improve cache_status to emit: <metadata block size> <#used metadata blocks>/<#total metadata blocks> <cache block size> <#used cache blocks>/<#total cache blocks> ... Adding the block sizes allows for easier calculation of the overall size of both the metadata and cache devices. Adding <#total cache blocks> provides useful context for how much of the cache is used. Unfortunately these additions to the status will require updates to users' scripts that monitor the cache status. But these changes help provide more comprehensive information about the cache device and will simplify tools that are being developed to manage dm-cache devices -- because they won't need to issue 3 operations to cobble together the information that we can easily provide via a single status ioctl. While updating the status documentation in cache.txt spaces were tabify'd. Requested-by: Jonathan Brassow <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Acked-by: Joe Thornber <[email protected]>
* | dm cache: actually resize cacheVincent Pelletier2013-12-101-1/+1
|/ | | | | | | | | | | | | | Commit f494a9c6b1b6dd9a9f21bbb75d9210d478eeb498 ("dm cache: cache shrinking support") broke cache resizing support. dm_cache_resize() is called with cache->cache_size before it gets updated to new_size, so it is a no-op. But the dm-cache superblock is updated with the new_size even though the backing dm-array is not resized. Fix this by passing the new_size to dm_cache_resize(). Signed-off-by: Vincent Pelletier <[email protected]> Acked-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: resolve small nits and improve DocumentationMike Snitzer2013-11-121-1/+1
| | | | | | | | Document passthrough mode, cache shrinking, and cache invalidation. Also, use strcasecmp() and hlist_unhashed(). Reported-by: Alasdair G Kergon <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: add cache block invalidation supportJoe Thornber2013-11-111-3/+222
| | | | | | | | | | | | | | Cache block invalidation is removing an entry from the cache without writing it back. Cache blocks can be invalidated via the 'invalidate_cblocks' message, which takes an arbitrary number of cblock ranges: invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]* E.g. dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789 Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: add passthrough modeJoe Thornber2013-11-111-35/+174
| | | | | | | | | | | | | | | | | | | | | | | | | | | | "Passthrough" is a dm-cache operating mode (like writethrough or writeback) which is intended to be used when the cache contents are not known to be coherent with the origin device. It behaves as follows: * All reads are served from the origin device (all reads miss the cache) * All writes are forwarded to the origin device; additionally, write hits cause cache block invalidates This mode decouples cache coherency checks from cache device creation, largely to avoid having to perform coherency checks while booting. Boot scripts can create cache devices in passthrough mode and put them into service (mount cached filesystems, for example) without having to worry about coherency. Coherency that exists is maintained, although the cache will gradually cool as writes take place. Later, applications can perform coherency checks, the nature of which will depend on the type of the underlying storage. If coherency can be verified, the cache device can be transitioned to writethrough or writeback mode while still warm; otherwise, the cache contents can be discarded prior to transitioning to the desired operating mode. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Heinz Mauelshagen <[email protected]> Signed-off-by: Morgan Mears <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: cache shrinking supportJoe Thornber2013-11-111-9/+54
| | | | | | | | Allow a cache to shrink if the blocks being removed from the cache are not dirty. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: promotion optimisation for writesJoe Thornber2013-11-091-6/+87
| | | | | | | | | | | | If a write block triggers promotion and covers a whole block we can avoid a copy. Introduce dm_{hook,unhook}_bio to simplify saving and restoring bio fields (bi_private is now used by overwrite). Switch writethrough support over to using these helpers too. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: optimize commit_if_neededHeinz Mauelshagen2013-11-091-5/+7
| | | | | | | | | | | | Check commit_requested flag _before_ calling dm_cache_changed_this_transaction() superfluously. Also, be sure to set last_commit_jiffies _after_ dm_cache_commit() completes. Signed-off-by: Heinz Mauelshagen <[email protected]> Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: log error message if dm_kcopyd_copy() failsHeinz Mauelshagen2013-11-091-1/+3
| | | | | | | | A migration failure should be logged (albeit limited). Signed-off-by: Heinz Mauelshagen <[email protected]> Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: use cell_defer() boolean argument consistentlyHeinz Mauelshagen2013-11-091-4/+4
| | | | | | | | Fix a few cell_defer() calls that weren't passing a bool. Signed-off-by: Heinz Mauelshagen <[email protected]> Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: return -EINVAL if the user specifies unknown cache policyMikulas Patocka2013-11-091-6/+7
| | | | | | | | Return -EINVAL when the specified cache policy is unknown rather than returning -ENOMEM. Signed-off-by: Mikulas Patocka <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: improve efficiency of quiescing flag managementJoe Thornber2013-11-091-22/+5
| | | | | | | | Make the quiescing flag an atomic_t and stop protecting it with a spin lock. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: fix a race condition between queuing new migrations and quiescing ↵Joe Thornber2013-11-091-14/+40
| | | | | | | | | | | | | | | | for a shutdown The code that was trying to do this was inadequate. The postsuspend method (in ioctl context), needs to wait for the worker thread to acknowledge the request to quiesce. Otherwise the migration count may drop to zero temporarily before the worker thread realises we're quiescing. In this case the target will be taken down, but the worker thread may have issued a new migration, which will cause an oops when it completes. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Cc: [email protected] # 3.9+
* dm cache: io destined for the cache device can now serve as tick biosJoe Thornber2013-11-091-0/+1
| | | | | | | | | | | | Previously only origin bios could trigger ticks, which meant if all the io was destined for the cache no ticks were generated. If no ticks are generated then multiple hits, and movements in general, are attributed to the same tick. Only a stop gap fix, we need a better solution. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
* dm cache: eliminate holes in cache structureMike Snitzer2013-08-231-15/+15
| | | | | | | | | | Reorder members in the cache structure to eliminate 6 out of 7 holes (reclaiming 24 bytes). Also, the 'worker' and 'waker' members no longer straddle cachelines. Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]> Acked-by: Joe Thornber <[email protected]>
* dm cache: fix stacking of geometry limitsMike Snitzer2013-08-231-2/+10
| | | | | | | | | | | | | | Do not blindly override the queue limits (specifically io_min and io_opt). Allow traditional stacking of these limits if io_opt is a factor of the cache's data block size. Without this patch mkfs.xfs does not recognize the cache device's provided limits as a useful geometry (e.g. raid) so these hints are ignored. This was due to setting io_min to a useless value. Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]> Acked-by: Joe Thornber <[email protected]>
* dm cache: add data block size limits to code and DocumentationMike Snitzer2013-08-231-7/+10
| | | | | | | | | | | | Place upper bound on the cache's data block size (1GB). Inform users that the data block size can't be any arbitrary number, i.e. its value must be between 32KB and 1GB. Also, it should be a multiple of 32KB. Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]> Acked-by: Joe Thornber <[email protected]>
* dm cache: fix arm link errors with inlineMikulas Patocka2013-07-101-0/+4
| | | | | | | | | | | | | Use __always_inline to avoid a link failure with gcc 4.6 on ARM. gcc 4.7 is OK. It creates a function block_div.part.8, it references __udivdi3 and __umoddi3 and it is never called. The references to __udivdi3 and __umoddi3 cause a link failure. Reported-by: Rob Herring <[email protected]> Signed-off-by: Mikulas Patocka <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: set config valueJoe Thornber2013-05-101-28/+31
| | | | | | | | Share configuration option processing code between the dm cache ctr and message functions. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: move config fnsAlasdair G Kergon2013-05-101-17/+17
| | | | | | | Move process_config_option() in dm-cache-target.c to make the next patch more readable. Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: replace memcpy with struct assignmentJoe Thornber2013-05-101-1/+1
| | | | | | | Use struct assignment rather than memcpy in dm cache. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: fix typos in commentsJoe Thornber2013-05-101-3/+4
| | | | | | | Fix up some typos in dm-cache comments. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: tune migration throttlingJoe Thornber2013-05-101-1/+2
| | | | | | | | | | | | Tune the dm cache migration throttling. i) Issue a tick every second, just in case there's no i/o going through. ii) Drop the migration threshold right down to something suitable for background work. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: fix error return code in cache_createWei Yongjun2013-05-101-0/+1
| | | | | | | | | Return -ENOMEM if memory allocation fails in cache_create instead of 0 (to avoid NULL pointer dereference). Signed-off-by: Wei Yongjun <[email protected]> Cc: [email protected] Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: reduce bio front_pad size in writeback modeMike Snitzer2013-04-051-13/+34
| | | | | | | | | | | | | | | | A recent patch to fix the dm cache target's writethrough mode extended the bio's front_pad to include a 1056-byte struct dm_bio_details. Writeback mode doesn't need this, so this patch reduces the per_bio_data_size to 16 bytes in this case instead of 1096. The dm_bio_details structure was added in "dm cache: fix writes to cache device in writethrough mode" which fixed commit e2e74d617e ("dm cache: fix race in writethrough implementation"). In writeback mode we avoid allocating the writethrough-specific members of the per_bio_data structure (the dm_bio_details structure included). Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: fix writes to cache device in writethrough modeDarrick J. Wong2013-04-051-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The dm-cache writethrough strategy introduced by commit e2e74d617eadc15 ("dm cache: fix race in writethrough implementation") issues a bio to the origin device, remaps and then issues the bio to the cache device. This more conservative in-series approach was selected to favor correctness over performance (of the previous parallel writethrough). However, this in-series implementation that reuses the same bio to write both the origin and cache device didn't take into account that the block layer's req_bio_endio() modifies a completing bio's bi_sector and bi_size. So the new writethrough strategy needs to preserve these bio fields, and restore them before submission to the cache device, otherwise nothing gets written to the cache (because bi_size is 0). This patch adds a struct dm_bio_details field to struct per_bio_data, and uses dm_bio_record() and dm_bio_restore() to ensure the bio is restored before reissuing to the cache device. Adding such a large structure to the per_bio_data is not ideal but we can improve this later, for now correctness is the important thing. This problem initially went unnoticed because the dm-cache test-suite uses a linear DM device for the dm-cache device's origin device. Writethrough worked as expected because DM submits a *clone* of the original bio, so the original bio which was reused for the cache was never touched. Signed-off-by: Darrick J. Wong <[email protected]> Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: policy ignore hints if generated by different versionMike Snitzer2013-03-201-2/+1
| | | | | | | | | | | | | | | When reading the dm cache metadata from disk, ignore the policy hints unless they were generated by the same major version number of the same policy module. The hints are considered to be private data belonging to the specific module that generated them and there is no requirement for them to make sense to different versions of the policy that generated them. Policy modules are all required to work fine if no previous hints are supplied (or if existing hints are lost). Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: fix race in writethrough implementationJoe Thornber2013-03-201-50/+88
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have found a race in the optimisation used in the dm cache writethrough implementation. Currently, dm core sends the cache target two bios, one for the origin device and one for the cache device and these are processed in parallel. This patch avoids the race by changing the code back to a simpler (slower) implementation which processes the two writes in series, one after the other, until we can develop a complete fix for the problem. When the cache is in writethrough mode it needs to send WRITE bios to both the origin and cache devices. Previously we've been implementing this by having dm core query the cache target on every write to find out how many copies of the bio it wants. The cache will ask for two bios if the block is in the cache, and one otherwise. Then main problem with this is it's racey. At the time this check is made the bio hasn't yet been submitted and so isn't being taken into account when quiescing a block for migration (promotion or demotion). This means a single bio may be submitted when two were needed because the block has since been promoted to the cache (catastrophic), or two bios where only one is needed (harmless). I really don't want to start entering bios into the quiescing system (deferred_set) in the get_num_write_bios callback. Instead this patch simplifies things; only one bio is submitted by the core, this is first written to the origin and then the cache device in series. Obviously this will have a latency impact. deferred_writethrough_bios is introduced to record bios that must be later issued to the cache device from the worker thread. This deferred submission, after the origin bio completes, is required given that we're in interrupt context (writethrough_endio). Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: avoid calling policy destructor twice on errorHeinz Mauelshagen2013-03-201-1/+4
| | | | | | | | | | If the cache policy's config values are not able to be set we must set the policy to NULL after destroying it in create_cache_policy() so we don't attempt to destroy it a second time later. Signed-off-by: Heinz Mauelshagen <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: detect cache_create failureHeinz Mauelshagen2013-03-201-0/+2
| | | | | | | | | | | | | Return error if cache_create() fails. A missing return check made cache_ctr continue even after an error in cache_create() resulting in the cache object being destroyed. So a simple failure like an odd number of cache policy config value arguments would result in an oops. Signed-off-by: Heinz Mauelshagen <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm cache: avoid 64 bit division on 32 bitJoe Thornber2013-03-201-7/+14
| | | | | | | | | | | | | Squash various 32bit link errors. >> on i386: >> drivers/built-in.o: In function `is_discarded_oblock': >> dm-cache-target.c:(.text+0x1ea28e): undefined reference to `__udivdi3' ... Reported-by: Randy Dunlap <[email protected]> Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
* dm: add cache targetJoe Thornber2013-03-011-0/+2584
Add a target that allows a fast device such as an SSD to be used as a cache for a slower device such as a disk. A plug-in architecture was chosen so that the decisions about which data to migrate and when are delegated to interchangeable tunable policy modules. The first general purpose module we have developed, called "mq" (multiqueue), follows in the next patch. Other modules are under development. Signed-off-by: Joe Thornber <[email protected]> Signed-off-by: Heinz Mauelshagen <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Signed-off-by: Alasdair G Kergon <[email protected]>
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