- 27 5月, 2014 1 次提交
-
-
由 Heinz Mauelshagen 提交于
The DM cache target cannot cope with discards that span multiple cache blocks, so each discard bio that spans more than one cache block must get split by the DM core. Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # v3.9+
-
- 02 5月, 2014 1 次提交
-
-
由 Mike Snitzer 提交于
Commit 2ee57d58 ("dm cache: add passthrough mode") inadvertently removed the deferred set reference that was taken in cache_map()'s writethrough mode support. Restore taking this reference. This issue was found with code inspection. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com> Cc: stable@vger.kernel.org # 3.13+
-
- 05 4月, 2014 1 次提交
-
-
由 Joe Thornber 提交于
When suspending a cache the policy is walked and the individual policy hints written to the metadata via sync_metadata(). This led to this lock order: policy->lock cache_metadata->root_lock When loading the cache target the policy is populated while the metadata lock is held: cache_metadata->root_lock policy->lock Fix this potential lock-inversion (ABBA) deadlock in sync_metadata() by ensuring the cache_metadata root_lock is held whilst all the hints are written, rather than being repeatedly locked while policy->lock is held (as was the case with each callout that policy_walk_mappings() made to the old save_hint() method). Found by turning on the CONFIG_PROVE_LOCKING ("Lock debugging: prove locking correctness") build option. However, it is not clear how the LOCKDEP reported paths can lead to a deadlock since the two paths, suspending a target and loading a target, never occur at the same time. But that doesn't mean the same lock-inversion couldn't have occurred elsewhere. Reported-by: NMarian Csontos <mcsontos@redhat.com> Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
-
- 28 3月, 2014 2 次提交
-
-
由 Heinz Mauelshagen 提交于
Discard block size not being equal to cache block size causes data corruption by erroneously avoiding migrations in issue_copy() because the discard state is being cleared for a group of cache blocks when it should not. Completely remove all code that enabled a distinction between the cache block size and discard block size. Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Mike Snitzer 提交于
If the discard block size is larger than the cache block size we will not properly quiesce IO to a region that is about to be discarded. This results in a race between a cache migration where no copy is needed, and a write to an adjacent cache block that's within the same large discard block. Workaround this by limiting the discard_block_size to cache_block_size. Also limit the max_discard_sectors to cache_block_size. A more comprehensive fix that introduces range locking support in the bio_prison and proper quiescing of a discard range that spans multiple cache blocks is already in development. Reported-by: NMorgan Mears <Morgan.Mears@netapp.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com> Acked-by: NHeinz Mauelshagen <heinzm@redhat.com> Cc: stable@vger.kernel.org
-
- 13 3月, 2014 2 次提交
-
-
由 Heinz Mauelshagen 提交于
In order to avoid wasting cache space a partial block at the end of the origin device is not cached. Unfortunately, the check for such a partial block at the end of the origin device was flawed. Fix accesses beyond the end of the origin device that occured due to attempted promotion of an undetected partial block by: - initializing the per bio data struct to allow cache_end_io to work properly - recognizing access to the partial block at the end of the origin device - avoiding out of bounds access to the discard bitset Otherwise, users can experience errors like the following: attempt to access beyond end of device dm-5: rw=0, want=20971520, limit=20971456 ... device-mapper: cache: promotion failed; couldn't copy block Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
-
由 Heinz Mauelshagen 提交于
During demotion or promotion to a cache's >2TB fast device we must not truncate the cache block's associated sector to 32bits. The 32bit temporary result of from_cblock() caused a 32bit multiplication when calculating the sector of the fast device in issue_copy_real(). Use an intermediate 64bit type to store the 32bit from_cblock() to allow for proper 64bit multiplication. Here is an example of how this bug manifests on an ext4 filesystem: EXT4-fs error (device dm-0): ext4_mb_generate_buddy:756: group 17136, 32768 clusters in bitmap, 30688 in gd; block bitmap corrupt. JBD2: Spotted dirty metadata buffer (dev = dm-0, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
-
- 28 2月, 2014 1 次提交
-
-
由 Heinz Mauelshagen 提交于
When remapping a block to the cache's fast device that is larger than 2TB we must not truncate the destination sector to 32bits. The 32bit temporary result of from_cblock() was being overflowed in remap_to_cache() due to the logical left shift. Use an intermediate 64bit type to store the 32bit from_cblock() result to fix the overflow. Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
-
- 18 2月, 2014 2 次提交
-
-
由 Mike Snitzer 提交于
When completing an overwrite bio, in overwrite_endio(), the associated migration should not be added to the 'completed_migrations' until the bio's fields are restored with dm_unhook_bio(). Otherwise, do_worker() can race to process 'completed_migrations' before dm_unhook_bio() -- so the bio's bi_end_io is incorrect. This is unlikely to cause any problems given the current code but should be fixed on the basis of correctness. Also, the cache's spinlock only needs to be held when manipulating the 'completed_migrations' list -- other changes don't need protection. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com>
-
由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com> Cc: stable@vger.kernel.org # 3.13+
-
- 17 1月, 2014 1 次提交
-
-
由 Mike Snitzer 提交于
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: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
- 10 1月, 2014 1 次提交
-
-
由 Mike Snitzer 提交于
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: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com>
-
- 11 12月, 2013 1 次提交
-
-
由 Vincent Pelletier 提交于
Commit f494a9c6 ("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: NVincent Pelletier <plr.vincent@gmail.com> Acked-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
- 04 12月, 2013 1 次提交
-
-
由 Mike Snitzer 提交于
Move the bio->bi_remaining increment into dm_unhook_bio() so the overwrite_endio() handler works as expected. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 24 11月, 2013 2 次提交
-
-
由 Kent Overstreet 提交于
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: NKent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk>
-
由 Kent Overstreet 提交于
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: NKent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "Ed L. Cashin" <ecashin@coraid.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Lars Ellenberg <drbd-dev@lists.linbit.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Yehuda Sadeh <yehuda@inktank.com> Cc: Sage Weil <sage@inktank.com> Cc: Alex Elder <elder@inktank.com> Cc: ceph-devel@vger.kernel.org Cc: Joshua Morris <josh.h.morris@us.ibm.com> Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Neil Brown <neilb@suse.de> Cc: Alasdair Kergon <agk@redhat.com> Cc: Mike Snitzer <snitzer@redhat.com> Cc: dm-devel@redhat.com Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: linux390@de.ibm.com Cc: Boaz Harrosh <bharrosh@panasas.com> Cc: Benny Halevy <bhalevy@tonian.com> Cc: "James E.J. Bottomley" <JBottomley@parallels.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Chris Mason <chris.mason@fusionio.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Jaegeuk Kim <jaegeuk.kim@samsung.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Dave Kleikamp <shaggy@kernel.org> Cc: Joern Engel <joern@logfs.org> Cc: Prasad Joshi <prasadjoshi.linux@gmail.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Ben Myers <bpm@sgi.com> Cc: xfs@oss.sgi.com Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Len Brown <len.brown@intel.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com> Cc: Ben Hutchings <ben@decadent.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Guo Chao <yan@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Cc: "Roger Pau Monné" <roger.pau@citrix.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Cc: Ian Campbell <Ian.Campbell@citrix.com> Cc: Sebastian Ott <sebott@linux.vnet.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Jiang Liu <jiang.liu@huawei.com> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Jerome Marchand <jmarchand@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Peng Tao <tao.peng@emc.com> Cc: Andy Adamson <andros@netapp.com> Cc: fanchaoting <fanchaoting@cn.fujitsu.com> Cc: Jie Liu <jeff.liu@oracle.com> Cc: Sunil Mushran <sunil.mushran@gmail.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Pankaj Kumar <pankaj.km@samsung.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Mel Gorman <mgorman@suse.de>6
-
- 13 11月, 2013 1 次提交
-
-
由 Mike Snitzer 提交于
Document passthrough mode, cache shrinking, and cache invalidation. Also, use strcasecmp() and hlist_unhashed(). Reported-by: NAlasdair G Kergon <agk@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
- 12 11月, 2013 3 次提交
-
-
由 Joe Thornber 提交于
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: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Joe Thornber 提交于
"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: NJoe Thornber <ejt@redhat.com> Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Signed-off-by: NMorgan Mears <Morgan.Mears@netapp.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Joe Thornber 提交于
Allow a cache to shrink if the blocks being removed from the cache are not dirty. Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
- 10 11月, 2013 8 次提交
-
-
由 Joe Thornber 提交于
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: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Heinz Mauelshagen 提交于
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: NHeinz Mauelshagen <heinzm@redhat.com> Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Heinz Mauelshagen 提交于
A migration failure should be logged (albeit limited). Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Heinz Mauelshagen 提交于
Fix a few cell_defer() calls that weren't passing a bool. Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com> Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Mikulas Patocka 提交于
Return -EINVAL when the specified cache policy is unknown rather than returning -ENOMEM. Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Joe Thornber 提交于
Make the quiescing flag an atomic_t and stop protecting it with a spin lock. Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
由 Joe Thornber 提交于
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: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # 3.9+
-
由 Joe Thornber 提交于
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: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com>
-
- 23 8月, 2013 3 次提交
-
-
由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com>
-
由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com>
-
由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com> Acked-by: NJoe Thornber <ejt@redhat.com>
-
- 11 7月, 2013 1 次提交
-
-
由 Mikulas Patocka 提交于
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: NRob Herring <robherring2@gmail.com> Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
- 10 5月, 2013 6 次提交
-
-
由 Joe Thornber 提交于
Share configuration option processing code between the dm cache ctr and message functions. Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
由 Alasdair G Kergon 提交于
Move process_config_option() in dm-cache-target.c to make the next patch more readable. Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
由 Joe Thornber 提交于
Use struct assignment rather than memcpy in dm cache. Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
由 Joe Thornber 提交于
Fix up some typos in dm-cache comments. Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
由 Joe Thornber 提交于
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: NJoe Thornber <ejt@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
由 Wei Yongjun 提交于
Return -ENOMEM if memory allocation fails in cache_create instead of 0 (to avoid NULL pointer dereference). Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn> Cc: stable@vger.kernel.org Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
- 05 4月, 2013 2 次提交
-
-
由 Mike Snitzer 提交于
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 e2e74d61 ("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: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-
由 Darrick J. Wong 提交于
The dm-cache writethrough strategy introduced by commit e2e74d61 ("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: NDarrick J. Wong <darrick.wong@oracle.com> Signed-off-by: NJoe Thornber <ejt@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
-