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* dm cache metadata: Fix loading discard bitsetNikos Tsironis2019-04-181-1/+8
| | | | | | | | | | | | | Add missing dm_bitset_cursor_next() to properly advance the bitset cursor. Otherwise, the discarded state of all blocks is set according to the discarded state of the first block. Fixes: ae4a46a1f6 ("dm cache metadata: use bitset cursor api to load discard bitset") Cc: stable@vger.kernel.org Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: verify cache has blocks in blocks_are_clean_separate_dirty()Mike Snitzer2018-12-071-0/+4
| | | | | | | | | | | | | Otherwise dm_bitset_cursor_begin() return -ENODATA. Other calls to dm_bitset_cursor_begin() have similar negative checks. Fixes inability to create a cache in passthrough mode (even though doing so makes no sense). Fixes: 0d963b6e65 ("dm cache metadata: fix metadata2 format's blocks_are_clean_separate_dirty") Cc: stable@vger.kernel.org Reported-by: David Teigland <teigland@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: ignore hints array being too small during resizeJoe Thornber2018-10-041-2/+2
| | | | | | | | | | | | | | | | | Commit fd2fa9541 ("dm cache metadata: save in-core policy_hint_size to on-disk superblock") enabled previously written policy hints to be used after a cache is reactivated. But in doing so the cache metadata's hint array was left exposed to out of bounds access because on resize the metadata's on-disk hint array wasn't ever extended. Fix this by ignoring that there are no on-disk hints associated with the newly added cache blocks. An expanded on-disk hint array is later rewritten upon the next clean shutdown of the cache. Fixes: fd2fa9541 ("dm cache metadata: save in-core policy_hint_size to on-disk superblock") Cc: stable@vger.kernel.org Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: set dirty on all cache blocks after a crashIlya Dryomov2018-08-091-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Quoting Documentation/device-mapper/cache.txt: The 'dirty' state for a cache block changes far too frequently for us to keep updating it on the fly. So we treat it as a hint. In normal operation it will be written when the dm device is suspended. If the system crashes all cache blocks will be assumed dirty when restarted. This got broken in commit f177940a8091 ("dm cache metadata: switch to using the new cursor api for loading metadata") in 4.9, which removed the code that consulted cmd->clean_when_opened (CLEAN_SHUTDOWN on-disk flag) when loading cache blocks. This results in data corruption on an unclean shutdown with dirty cache blocks on the fast device. After the crash those blocks are considered clean and may get evicted from the cache at any time. This can be demonstrated by doing a lot of reads to trigger individual evictions, but uncache is more predictable: ### Disable auto-activation in lvm.conf to be able to do uncache in ### time (i.e. see uncache doing flushing) when the fix is applied. # xfs_io -d -c 'pwrite -b 4M -S 0xaa 0 1G' /dev/vdb # vgcreate vg_cache /dev/vdb /dev/vdc # lvcreate -L 1G -n lv_slowdev vg_cache /dev/vdb # lvcreate -L 512M -n lv_cachedev vg_cache /dev/vdc # lvcreate -L 256M -n lv_metadev vg_cache /dev/vdc # lvconvert --type cache-pool --cachemode writeback vg_cache/lv_cachedev --poolmetadata vg_cache/lv_metadev # lvconvert --type cache vg_cache/lv_slowdev --cachepool vg_cache/lv_cachedev # xfs_io -d -c 'pwrite -b 4M -S 0xbb 0 512M' /dev/mapper/vg_cache-lv_slowdev # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2 0fe00000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ 0fe00010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ # dmsetup status vg_cache-lv_slowdev 0 2097152 cache 8 27/65536 128 8192/8192 1 100 0 0 0 8192 7065 2 metadata2 writeback 2 migration_threshold 2048 smq 0 rw - ^^^^ 7065 * 64k = 441M yet to be written to the slow device # echo b >/proc/sysrq-trigger # vgchange -ay vg_cache # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2 0fe00000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ 0fe00010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ # lvconvert --uncache vg_cache/lv_slowdev Flushing 0 blocks for cache vg_cache/lv_slowdev. Logical volume "lv_cachedev" successfully removed Logical volume vg_cache/lv_slowdev is not cached. # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2 0fe00000: aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................ 0fe00010: aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................ This is the case with both v1 and v2 cache pool metatata formats. After applying this patch: # vgchange -ay vg_cache # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2 0fe00000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ 0fe00010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ # lvconvert --uncache vg_cache/lv_slowdev Flushing 3724 blocks for cache vg_cache/lv_slowdev. ... Flushing 71 blocks for cache vg_cache/lv_slowdev. Logical volume "lv_cachedev" successfully removed Logical volume vg_cache/lv_slowdev is not cached. # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2 0fe00000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ 0fe00010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Cc: stable@vger.kernel.org Fixes: f177940a8091 ("dm cache metadata: switch to using the new cursor api for loading metadata") Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: save in-core policy_hint_size to on-disk superblockMike Snitzer2018-08-071-1/+2
| | | | | | | | | | | | | | | | | | | | | | policy_hint_size starts as 0 during __write_initial_superblock(). It isn't until the policy is loaded that policy_hint_size is set in-core (cmd->policy_hint_size). But it never got recorded in the on-disk superblock because __commit_transaction() didn't deal with transfering the in-core cmd->policy_hint_size to the on-disk superblock. The in-core cmd->policy_hint_size gets initialized by metadata_open()'s __begin_transaction_flags() which re-reads all superblock fields. Because the superblock's policy_hint_size was never properly stored, when the cache was created, hints_array_available() would always return false when re-activating a previously created cache. This means __load_mappings() always considered the hints invalid and never made use of the hints (these hints served to optimize). Another detremental side-effect of this oversight is the cache_check utility would fail with: "invalid hint width: 0" Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache: convert dm_cache_metadata.ref_count from atomic_t to refcount_tElena Reshetova2017-10-241-4/+5
| | | | | | | | | | | | | | | | | | | | | | | | | atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable dm_cache_metadata.ref_count is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: fail operations if fail_io mode has been establishedMike Snitzer2017-05-051-4/+8
| | | | | | | | | | Otherwise it is possible to trigger crashes due to the metadata being inaccessible yet these methods don't safely account for that possibility without these checks. Cc: stable@vger.kernel.org Reported-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* Merge tag 'for-4.12/dm-changes' of ↵Linus Torvalds2017-05-031-3/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - A major update for DM cache that reduces the latency for deciding whether blocks should migrate to/from the cache. The bio-prison-v2 interface supports this improvement by enabling direct dispatch of work to workqueues rather than having to delay the actual work dispatch to the DM cache core. So the dm-cache policies are much more nimble by being able to drive IO as they see fit. One immediate benefit from the improved latency is a cache that should be much more adaptive to changing workloads. - Add a new DM integrity target that emulates a block device that has additional per-sector tags that can be used for storing integrity information. - Add a new authenticated encryption feature to the DM crypt target that builds on the capabilities provided by the DM integrity target. - Add MD interface for switching the raid4/5/6 journal mode and update the DM raid target to use it to enable aid4/5/6 journal write-back support. - Switch the DM verity target over to using the asynchronous hash crypto API (this helps work better with architectures that have access to off-CPU algorithm providers, which should reduce CPU utilization). - Various request-based DM and DM multipath fixes and improvements from Bart and Christoph. - A DM thinp target fix for a bio structure leak that occurs for each discard IFF discard passdown is enabled. - A fix for a possible deadlock in DM bufio and a fix to re-check the new buffer allocation watermark in the face of competing admin changes to the 'max_cache_size_bytes' tunable. - A couple DM core cleanups. * tag 'for-4.12/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (50 commits) dm bufio: check new buffer allocation watermark every 30 seconds dm bufio: avoid a possible ABBA deadlock dm mpath: make it easier to detect unintended I/O request flushes dm mpath: cleanup QUEUE_IF_NO_PATH bit manipulation by introducing assign_bit() dm mpath: micro-optimize the hot path relative to MPATHF_QUEUE_IF_NO_PATH dm: introduce enum dm_queue_mode to cleanup related code dm mpath: verify __pg_init_all_paths locking assumptions at runtime dm: verify suspend_locking assumptions at runtime dm block manager: remove an unused argument from dm_block_manager_create() dm rq: check blk_mq_register_dev() return value in dm_mq_init_request_queue() dm mpath: delay requeuing while path initialization is in progress dm mpath: avoid that path removal can trigger an infinite loop dm mpath: split and rename activate_path() to prepare for its expanded use dm ioctl: prevent stack leak in dm ioctl call dm integrity: use previously calculated log2 of sectors_per_block dm integrity: use hex2bin instead of open-coded variant dm crypt: replace custom implementation of hex2bin() dm crypt: remove obsolete references to per-CPU state dm verity: switch to using asynchronous hash crypto API dm crypt: use WQ_HIGHPRI for the IO and crypt workqueues ...
| * dm block manager: remove an unused argument from dm_block_manager_create()Bart Van Assche2017-04-271-3/+0
| | | | | | | | | | | | | | | | | | | | The 'cache_size' argument of dm_block_manager_create() has never been used. Remove it along with the definitions of the constants passed as the 'cache_size' argument. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* | dm cache metadata: fix metadata2 format's blocks_are_clean_separate_dirtyJoe Thornber2017-03-201-3/+5
|/ | | | | | | | | | The dm_bitset_cursor_begin() call was using the incorrect nr_entries. Also, the last dm_bitset_cursor_next() must be avoided if we're at the end of the cursor. Fixes: 7f1b21591a6 ("dm cache metadata: use cursor api in blocks_are_clean_separate_dirty()") Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: use cursor api in blocks_are_clean_separate_dirty()Mike Snitzer2017-02-161-7/+26
| | | | Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: use dm_bitset_new() to create the dirty bitset in format 2Joe Thornber2017-02-161-11/+11
| | | | | | | Big speed up with large configs. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: name the cache block that couldn't be loadedMike Snitzer2017-02-161-4/+8
| | | | | | | | Improves __load_mapping_v1() and __load_mapping_v2() DMERR messages to explicitly name the cache block number whose mapping couldn't be loaded. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: add "metadata2" featureJoe Thornber2017-02-161-33/+245
| | | | | | | | | If "metadata2" is provided as a table argument when creating/loading a cache target a more compact metadata format, with separate dirty bits, is used. "metadata2" improves speed of shutting down a cache target. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: use bitset cursor api to load discard bitsetJoe Thornber2017-02-161-20/+28
| | | | | Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: remove an extra newline in DMERR and codeMike Snitzer2016-11-211-2/+1
| | | | Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: switch to using the new cursor api for loading metadataJoe Thornber2016-09-221-23/+80
| | | | | | | This change offers a pretty significant performance improvement. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache: speed up writing of the hint arrayJoe Thornber2016-09-221-53/+27
| | | | | | | | | | | It's far quicker to always delete the hint array and recreate with dm_array_new() because we avoid the copying caused by mutation. Also simplifies the policy interface, replacing the walk_hints() with the simpler get_hint(). Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: fix cmd_read_lock() acquiring write lockAhmed Samy2016-04-171-2/+2
| | | | | | | | | | | | Commit 9567366fefdd ("dm cache metadata: fix READ_LOCK macros and cleanup WRITE_LOCK macros") uses down_write() instead of down_read() in cmd_read_lock(), yet up_read() is used to release the lock in READ_UNLOCK(). Fix it. Fixes: 9567366fefdd ("dm cache metadata: fix READ_LOCK macros and cleanup WRITE_LOCK macros") Cc: stable@vger.kernel.org Signed-off-by: Ahmed Samy <f.fallen45@gmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: fix READ_LOCK macros and cleanup WRITE_LOCK macrosMike Snitzer2016-04-141-24/+40
| | | | | | | | | | | | | | | | | | | The READ_LOCK macro was incorrectly returning -EINVAL if dm_bm_is_read_only() was true -- it will always be true once the cache metadata transitions to read-only by dm_cache_metadata_set_read_only(). Wrap READ_LOCK and WRITE_LOCK multi-statement macros in do {} while(0). Also, all accesses of the 'cmd' argument passed to these related macros are now encapsulated in parenthesis. A follow-up patch can be developed to eliminate the use of macros in favor of pure C code. Avoiding that now given that this needs to apply to stable@. Reported-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Fixes: d14fcf3dd79 ("dm cache: make sure every metadata function checks fail_io") Cc: stable@vger.kernel.org
* dm cache: make sure every metadata function checks fail_ioJoe Thornber2016-03-101-39/+59
| | | | | | | | | | Otherwise operations may be attempted that will only ever go on to crash (since the metadata device is either missing or unreliable if 'fail_io' is set). Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
* Merge tag 'dm-4.4-changes' of ↵Linus Torvalds2015-11-041-2/+6
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: "Smaller set of DM changes for this merge. I've based these changes on Jens' for-4.4/reservations branch because the associated DM changes required it. - Revert a dm-multipath change that caused a regression for unprivledged users (e.g. kvm guests) that issued ioctls when a multipath device had no available paths. - Include Christoph's refactoring of DM's ioctl handling and add support for passing through persistent reservations with DM multipath. - All other changes are very simple cleanups" * tag 'dm-4.4-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm switch: simplify conditional in alloc_region_table() dm delay: document that offsets are specified in sectors dm delay: capitalize the start of an delay_ctr() error message dm delay: Use DM_MAPIO macros instead of open-coded equivalents dm linear: remove redundant target name from error messages dm persistent data: eliminate unnecessary return values dm: eliminate unused "bioset" process for each bio-based DM device dm: convert ffs to __ffs dm: drop NULL test before kmem_cache_destroy() and mempool_destroy() dm: add support for passing through persistent reservations dm: refactor ioctl handling Revert "dm mpath: fix stalls when handling invalid ioctls" dm: initialize non-blk-mq queue data before queue is used
| * dm persistent data: eliminate unnecessary return valuesMikulas Patocka2015-10-311-2/+6
| | | | | | | | | | | | | | | | | | | | | | dm_bm_unlock and dm_tm_unlock return an integer value but the returned value is always 0. The calling code sometimes checks the return value and sometimes doesn't. Eliminate these unnecessary return values and also the checks for them. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* | dm cache: the CLEAN_SHUTDOWN flag was not being setJoe Thornber2015-10-231-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the CLEAN_SHUTDOWN flag is not set when a cache is loaded then all cache blocks are marked as dirty and a full writeback occurs. __commit_transaction() is responsible for setting/clearing CLEAN_SHUTDOWN (based the flags_mutator that is passed in). Fix this issue, of the cache's on-disk flags being wrong, by making sure __commit_transaction() does not reset the flags after the mutator has altered the flags in preparation for them being serialized to disk. before: sb_flags = mutator(le32_to_cpu(disk_super->flags)); disk_super->flags = cpu_to_le32(sb_flags); disk_super->flags = cpu_to_le32(cmd->flags); after: disk_super->flags = cpu_to_le32(cmd->flags); sb_flags = mutator(le32_to_cpu(disk_super->flags)); disk_super->flags = cpu_to_le32(sb_flags); Reported-by: Bogdan Vasiliev <bogdan.vasiliev@gmail.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
* dm cache: add fail io mode and needs_check flagJoe Thornber2015-06-111-19/+114
| | | | | | | | | | | | | | | | | | | | If a cache metadata operation fails (e.g. transaction commit) the cache's metadata device will abort the current transaction, set a new needs_check flag, and the cache will transition to "read-only" mode. If aborting the transaction or setting the needs_check flag fails the cache will transition to "fail-io" mode. Once needs_check is set the cache device will not be allowed to activate. Activation requires write access to metadata. Future work is needed to add proper support for running the cache in read-only mode. Once in fail-io mode the cache will report a status of "Fail". Also, add commit() wrapper that will disallow commits if in read_only or fail mode. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache: fix missing ERR_PTR returns and handlingJoe Thornber2015-01-281-4/+5
| | | | | | | | | | | | Commit 9b1cc9f251 ("dm cache: share cache-metadata object across inactive and active DM tables") mistakenly ignored the use of ERR_PTR returns. Restore missing IS_ERR checks and ERR_PTR returns where appropriate. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
* dm cache: share cache-metadata object across inactive and active DM tablesJoe Thornber2015-01-231-6/+95
| | | | | | | | | | | | | | | | If a DM table is reloaded with an inactive table when the device is not suspended (normal procedure for LVM2), then there will be two dm-bufio objects that can diverge. This can lead to a situation where the inactive table uses bufio to read metadata at the same time the active table writes metadata -- resulting in the inactive table having stale metadata buffers once it is promoted to the active table slot. Fix this by using reference counting and a global list of cache metadata objects to ensure there is only one metadata object per metadata device. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
* dm cache: revert "remove remainder of distinct discard block size"Joe Thornber2014-11-101-17/+17
| | | | | | | | | | This reverts commit 64ab346a360a4b15c28fb8531918d4a01f4eabd9 because we actually do want to allow the discard blocksize to be larger than the cache blocksize. Further dm-cache discard changes will make this possible. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: use dm-space-map-metadata.h defined size limitsMike Snitzer2014-08-011-2/+2
| | | | | | | | | | | | | Commit 7d48935e cleaned up the persistent-data's space-map-metadata limits by elevating them to dm-space-map-metadata.h. Update dm-cache-metadata to use these same limits. The calculation for DM_CACHE_METADATA_MAX_SECTORS didn't account for the sizeof the disk_bitmap_header. So the supported maximum metadata size is a bit smaller (reduced from 33423360 to 33292800 sectors). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Joe Thornber <ejt@redhat.com>
* dm cache metadata: do not allow the data block size to changeMike Snitzer2014-07-151-0/+9
| | | | | | | | | | The block size for the dm-cache's data device must remained fixed for the life of the cache. Disallow any attempt to change the cache's data block size. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Joe Thornber <ejt@redhat.com> Cc: stable@vger.kernel.org
* dm cache: fix a lock-inversionJoe Thornber2014-04-041-18/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: Marian Csontos <mcsontos@redhat.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
* dm: take care to copy the space map roots before locking the superblockJoe Thornber2014-03-271-22/+38
| | | | | | | | | | | | In theory copying the space map root can fail, but in practice it never does because we're careful to check what size buffer is needed. But make certain we're able to copy the space map roots before locking the superblock. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # drop dm-era and dm-cache changes as needed
* dm transaction manager: fix corruption due to non-atomic transaction commitJoe Thornber2014-03-271-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The persistent-data library used by dm-thin, dm-cache, etc is transactional. If anything goes wrong, such as an io error when writing new metadata or a power failure, then we roll back to the last transaction. Atomicity when committing a transaction is achieved by: a) Never overwriting data from the previous transaction. b) Writing the superblock last, after all other metadata has hit the disk. This commit and the following commit ("dm: take care to copy the space map roots before locking the superblock") fix a bug associated with (b). When committing it was possible for the superblock to still be written in spite of an io error occurring during the preceeding metadata flush. With these commits we're careful not to take the write lock out on the superblock until after the metadata flush has completed. Change the transaction manager's semantics for dm_tm_commit() to assume all data has been flushed _before_ the single superblock that is passed in. As a prerequisite, split the block manager's block unlocking and flushing by simplifying dm_bm_flush_and_unlock() to dm_bm_flush(). Now the unlocking must be done separately. This issue was discovered by forcing io errors at the crucial time using dm-flakey. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
* dm cache: remove remainder of distinct discard block sizeHeinz Mauelshagen2014-03-271-17/+17
| | | | | | | | | | | | | 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: Heinz Mauelshagen <heinzm@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: check the metadata version when reading the superblockJoe Thornber2013-11-111-3/+21
| | | | | | | Need to check the version to verify on-disk metadata is supported. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache: add passthrough modeJoe Thornber2013-11-111-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | "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 <ejt@redhat.com> Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com> Signed-off-by: Morgan Mears <Morgan.Mears@netapp.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache: cache shrinking supportJoe Thornber2013-11-111-0/+66
| | | | | | | | Allow a cache to shrink if the blocks being removed from the cache are not dirty. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache metadata: return bool from __superblock_all_zeroesJoe Thornber2013-11-091-4/+5
| | | | | Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm cache: replace memcpy with struct assignmentJoe Thornber2013-05-101-2/+2
| | | | | | | Use struct assignment rather than memcpy in dm cache. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm cache: policy ignore hints if generated by different versionMike Snitzer2013-03-201-10/+37
| | | | | | | | | | | | | | | 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 <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm cache: policy change version from string to integer setMike Snitzer2013-03-201-2/+13
| | | | | | | | | | Separate dm cache policy version string into 3 unsigned numbers corresponding to major, minor and patchlevel and store them at the end of the on-disk metadata so we know which version of the policy generated the hints in case a future version wants to use them differently. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm cache: metadata clear dirty bits on clean shutdownJoe Thornber2013-03-201-1/+1
| | | | | | | | | | | | When writing the dirty bitset to the metadata device on a clean shutdown, clear the dirty bits. Previously they were left indicating the cache was dirty. This led to confusion about whether there really was dirty data in the cache or not. (This was a harmless bug.) Reported-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: add cache targetJoe Thornber2013-03-011-0/+1146
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 <ejt@redhat.com> Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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