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* dm thin metadata: split __open or format metadataJoe Thornber2012-07-271-50/+74
| | | | | | | | | Split __open_or_format_metadata into __format_metadata and __open_metadata in dm-thin-metadata. 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 thin metadata: use struct dm_pool_metadata members in ↵Joe Thornber2012-07-271-23/+17
| | | | | | | | | | | __open_or_format_metadata Clean up __open_or_format_metadata in dm-thin-metadata by using struct dm_pool_metadata members to replace local variables. 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 thin metadata: zero unused superblock uuidJoe Thornber2012-07-271-0/+1
| | | | | | | | Zero the unused uuid when initialising the metadata superblock. 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 thin metadata: lift __begin_transaction out of __write_initial_superblockJoe Thornber2012-07-271-13/+6
| | | | | | | | | Lift the call to __begin_transaction out of __write_initial_superblock in dm-thin-metadata. Called higher up the call chain now. 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 thin metadata: move dm_commit_pool_metadata into __write_initial_superblockJoe Thornber2012-07-271-6/+38
| | | | | | | | Move dm_commit_pool_metadata inline into __write_initial_superblock in dm-thin-metadata. 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 thin metadata: factor out __write_initial_superblockJoe Thornber2012-07-271-51/+58
| | | | | | | | | Factor out __write_initial_superblock and also pull some other initial creation code out of dm_pool_metadata_open. 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 thin metadata: lift some initialisation out of __open_or_format_metadataJoe Thornber2012-07-271-4/+4
| | | | | | | | Lift some initialisation out of __open_or_format_metadata in dm-thin-metadata. 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 thin metadata: factor __destroy_persistent_data out of dm_pool_metadata_closeJoe Thornber2012-07-271-5/+10
| | | | | | | | Factor __destroy_persistent_data_objects out of dm_pool_metadata_close. 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 thin metadata: move bm creation code into create_persistent_data_objectsJoe Thornber2012-07-271-24/+32
| | | | | | | | | Move block manager creation and the check for unformatted metadata into __create_persistent_data_objects(). 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 thin metadata: rename init_pmd to __create_persistent_data_objectsJoe Thornber2012-07-271-4/+4
| | | | | | | | Rename init_pmd to __create_persistent_data_objects in dm-thin-metadata. 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 thin metadata: wrap superblock lockingJoe Thornber2012-07-271-21/+20
| | | | | | | | | Introduce wrappers to handle write locking the superblock appropriately. 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 persistent data: stop using dm_bm_unlock_move when shadowing blocks in tmJoe Thornber2012-07-273-27/+14
| | | | | | | | | | | | | | | | Stop using dm_bm_unlock_move when shadowing blocks in the transaction manager as an optimisation and remove the function as it is then no longer used. Some code, such as the space maps, keeps using on-disk data structures from the previous transaction. It can do this because blocks won't be reallocated until the subsequent transaction. Using dm_bm_unlock_move to copy blocks sounds like a win, but it forces a synchronous read should the old block be accessed. 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 persistent data: tidy transaction manager creation fnsJoe Thornber2012-07-274-55/+46
| | | | | | | | | | | | | Tidy the transaction manager creation functions. They no longer lock the superblock. Superblock locking is pulled out to the caller. Also export dm_bm_write_lock_zero. 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 thin metadata: stop tracking need for commitJoe Thornber2012-07-271-38/+2
| | | | | | | | | | | | | | Remove an optimisation that tracks whether or not a thin metadata commit is needed. If dm_pool_commit_metadata() is called and no changes have been made to the metadata then this optimisation avoided writing to disk. Removing because we're going to do something better later. 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 persistent data: create new dm_block_manager structJoe Thornber2012-07-272-23/+41
| | | | | | | | | | | | | | | This patch introduces a separate struct for the block_manager. It also uses IS_ERR to check the return value of dm_bufio_client_create instead of testing incorrectly for NULL. Prior to this patch a struct dm_block_manager was really an alias for a struct dm_bufio_client. We want to add some functionality to the block manager that will require extra fields, so this one to one mapping is no longer valid. 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 thin metadata: factor __setup_btree_details out of init_pmdJoe Thornber2012-07-271-35/+39
| | | | | | | | Factor __setup_btree_details out of init_pmd in dm-thin-metadata. 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: use bool bitfields in struct dm_targetAlasdair G Kergon2012-07-273-6/+6
| | | | | | Use boolean bit fields for flags in struct dm_target. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin: set flush_supportedJoe Thornber2012-07-271-0/+1
| | | | | | | | | | The thin provisioning target commits internal metadata on flush. So it should receive flushes regardless of whether the underlying devices support them. 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: allow targets to request flushes regardless of underlying device supportJoe Thornber2012-07-271-0/+3
| | | | | | | | | | | Allow targets to override the 'supports flush' calculation. Set 'flush_supported' if a target needs to receive flushes regardless of whether or not its underlying devices have support. 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 persistent data: only commit space map if index changedJoe Thornber2012-07-272-1/+12
| | | | | | | | | Introduce bitmap_index_changed to track whether or not the index changed then only commit a space map if it did. 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 persistent data: always unlock superblock in dm_bm_flush_and_unlockJoe Thornber2012-07-271-12/+4
| | | | | | | | | | | | | | Unlock the superblock even if initial dm_bufio_write_dirty_buffers fails. Also, remove redundant flush calls. dm_bm_flush_and_unlock's calls to dm_bufio_write_dirty_buffers already result in dm_bufio_issue_flush being called. This avoids warnings about unflushed dirty buffers from bufio. 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 thin: avoid unnecessarily breaking sharing for flushesJoe Thornber2012-07-271-1/+1
| | | | | | | | | There's no need to break sharing, triggering a copy, for a write that has no data (i.e. a flush). 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 thin: fix memory leak in process_prepared_mapping error pathsJoe Thornber2012-07-271-2/+3
| | | | | | | | | | | Fix memory leak in process_prepared_mapping by always freeing the dm_thin_new_mapping structs from the mapping_pool mempool on the error paths. Signed-off-by: Joe Thornber <ejt@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm crypt: rename struct convert_context sector fieldMikulas Patocka2012-07-271-6/+6
| | | | | | | | | | Rename sector to cc_sector in dm-crypt's convert_context struct. This is preparation for a future patch that merges dm_io and convert_context which both have a "sector" field. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm crypt: store crypt_config instead of dm_target structAlasdair G Kergon2012-07-271-20/+18
| | | | | | | | | | | Store the crypt_config struct pointer directly in struct dm_crypt_io instead of the dm_target struct pointer. Target information is never used - only target->private is referenced, thus we can change it to point directly to struct crypt_config. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm crypt: move cipher data out of per_cpu structMikulas Patocka2012-07-271-69/+65
| | | | | | | | | | Move static dm-crypt cipher data out of per-cpu structure. Cipher information is static, so it does not have to be in a per-cpu structure. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm crypt: rename pending fieldMikulas Patocka2012-07-271-13/+13
| | | | | | | | | | | | There are two dm crypt structures that have a field called "pending". This patch renames them to "cc_pending" and "io_pending" to reduce confusion and ease searching the code. Also remove unnecessary initialisation of r in crypt_convert_block(). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid: move sectors_per_dev calculationJonathan E Brassow2012-07-271-9/+9
| | | | | | | | | | In preparation for RAID10 inclusion in dm-raid, we move the sectors_per_dev calculation later in the device creation process. This is because we won't know up-front how many stripes vs how many mirrors there are which will change the calculation. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid: restructure parse_raid_paramsJonathan E Brassow2012-07-271-5/+20
| | | | | | | | | In preparation for RAID10 addition to dm-raid, we change an 'if' conditional to a 'switch' conditional to make it easier to see what is being checked for each RAID type. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm mpath: add retain_attached_hw_handler featureMike Snitzer2012-07-271-6/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A SCSI device handler might get attached to a device during the initial device scan. We do not necessarily want to override this when loading a multipath table, so this patch adds a new multipath feature argument "retain_attached_hw_handler". During SCSI device scan all loaded SCSI device handlers will be consulted for a match (via scsi_dh's provided .match). If a match is found that device handler will be attached. We need a way to have userspace multipathd's provided 'hw_handler' not override the already attached hardware handler. When specifying the new feature 'retain_attached_hw_handler' multipath will use the currently attached hardware handler instead of trying to attach the one specified during table load. If no hardware handler is attached the specified hardware handler will still be used. Leverages scsi_dh_attach's ability to increment the scsi_dh's reference count if the same scsi_dh name is provided when attaching - currently attached scsi_dh name is determined with scsi_dh_attached_handler_name. Depends upon commit 7e8a74b177f17d100916b6ad415450f7c9508691 ("[SCSI] scsi_dh: add scsi_dh_attached_handler_name"). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Tested-by: Babu Moger <babu.moger@netapp.com> Reviewed-by: Chandra Seetharaman <sekharan@us.ibm.com> Acked-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin: optimize power of two block sizeMikulas Patocka2012-07-271-7/+16
| | | | | | | | | | | | | | | | dm-thin will be most likely used with a block size that is a power of two. So it should be optimized for this case. This patch changes division and modulo operations to shifts and bit masks if block size is a power of two. A test that bi_sector is divisible by a block size is removed from io_overlaps_block. Device mapper never sends bios that span a block boundary. Consequently, if we tested that bi_size is equivalent to block size, bi_sector must already be on a block boundary. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin: split discards on block boundaryMikulas Patocka2012-07-271-9/+7
| | | | | | | | | | | | | | This patch sets the variable "ti->split_discard_requests" for the dm thin target so that device mapper core splits discard requests on a block boundary. Consequently, a discard request that spans multiple blocks is never sent to dm-thin. The patch also removes some code in process_discard that deals with discards that span multiple blocks. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: introduce split_discard_requestsMikulas Patocka2012-07-271-1/+4
| | | | | | | | | | | | This patch introduces a new variable split_discard_requests. It can be set by targets so that discard requests are split on max_io_len boundaries. When split_discard_requests is not set, discard requests are only split on boundaries between targets, as was the case before this patch. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin: support for non power of 2 pool blocksizeMike Snitzer2012-07-271-22/+37
| | | | | | | | | | | | | | | | | | | | Non power of 2 blocksize support is needed to properly align thinp IO on storage that has non power of 2 optimal IO sizes (e.g. RAID6 10+2). Use sector_div to support non power of 2 blocksize for the pool's data device. This provides comparable performance to the power of 2 math that was performed until now (as tested on modern x86_64 hardware). The kernel currently assumes that limits->discard_granularity is a power of two so the thin target only enables discard support if the block size is a power of two. Eliminate pool structure's 'block_shift', 'offset_mask' and remaining 4 byte holes. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm stripe: optimize chunk_size calculationsMikulas Patocka2012-07-271-3/+23
| | | | | | | | | | dm-stripe is usually used with a chunk size that is a power of two. Use faster shifts and bit masks in such cases. stripe_width is already optimized in a similar way. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm stripe: remove minimum stripe sizeMikulas Patocka2012-07-271-2/+1
| | | | | | | | | | | There is no technical limitation in device mapper that would prevent the dm-stripe target from using a stripe size smaller than page size. This patch removes the limit and makes stripe volumes portable across architectures with different page size. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm stripe: support for non power of 2 chunksizeMike Snitzer2012-07-271-25/+19
| | | | | | | | | | Support non-power-of-2 chunk sizes with dm striping for proper alignment of stripe IO on storage that has non-power-of-2 optimal IO sizes (e.g. RAID6 10+2). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: support non power of two target max_io_lenMike Snitzer2012-07-276-29/+60
| | | | | | | | | | | | | Remove the restriction that limits a target's specified maximum incoming I/O size to be a power of 2. Rename this setting from 'split_io' to the less-ambiguous 'max_io_len'. Change it from sector_t to uint32_t, which is plenty big enough, and introduce a wrapper function dm_set_target_max_io_len() to set it. Use sector_div() to process it now that it is not necessarily a power of 2. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm stripe: remove stripes_maskMikulas Patocka2012-07-271-6/+3
| | | | | | | | | | | The structure stripe_c contains a stripes_mask field. This field is useless because it can be trivially calculated by subtracting one from stripes. It is used only at one place. This patch removes it. The patch also changes ffs(stripes) - 1 to __ffs(stripes). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm stripe: fix size testMikulas Patocka2012-07-271-1/+0
| | | | | | | | | | | | | | | | | | | dm-stripe is supposed to ensure that all the space allocated to the stripes is fully used and that all stripes are the same size. This patch fixes the test. It checks that device length is divisible by the chunk size and checks that the resulting quotient is divisible by the number of stripes (which is equivalent to testing if device length is divisible by chunk_size * stripes). Previously, the code only tested that the number of sectors in the target was divisible by each of the chunk size and the number of stripes separately, which could leave entire stripes unused. (A setup that genuinely needs some stripes to be shorter than others can be created by concatenating striped targets.) Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin: provide specific errors for two table load failure casesMike Snitzer2012-07-271-2/+6
| | | | | | | | | | | Provide specific error message strings for two pool_ctr() failure cases that currently give just "Unknown error". Reference: test_two_pools_pointing_to_the_same_metadata_fails and test_different_pool_cant_replace_pool in thinp-test-suite. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: replace simple_strtoulmajianpeng2012-07-273-18/+7
| | | | | | | | Replace obsolete simple_strtoul() with kstrtou8/kstrtouint. Signed-off-by: majianpeng <majianpeng@gmail.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: remove redundant assignment in merge fnAlasdair G Kergon2012-07-271-1/+0
| | | | | | | Remove redundant bvm->bi_sector self-assignment in dm snapshot's origin_merge(). Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin metadata: introduce THIN_MAX_CONCURRENT_LOCKSJoe Thornber2012-07-271-6/+8
| | | | | | | | | Introduce THIN_MAX_CONCURRENT_LOCKS into dm-thin-metadata to give a name to an otherwise "magic" number. 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 thin metadata: remove pointless label from __commit_transactionJoe Thornber2012-07-271-8/+7
| | | | | | | | | Remove the pointless label 'out' from __commit_transaction in dm-thin-metadata.c 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 persistent data: remove debug space map checkerJoe Thornber2012-07-276-534/+11
| | | | | | | | | | | | | | | | | | Remove debug space map checker from dm persistent data. The space map checker is a wrapper for other space maps that double checks the reference counts are correct. It holds all these reference counts in memory rather than on disk, so uses a lot of memory and is thus restricted to small pools. As yet, this checker hasn't found any issues, but has caused a few of its own due to people turning it on by default with larger pools. Removing. 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 thin: clean up compiler warningMike Snitzer2012-07-273-3/+3
| | | | | | | | | Clean up "warning: dubious: !x & y". Also make it clear that __snapshotted_since() returns a bool and that dm_thin_lookup_result's 'shared' member is a flag. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin: reduce endio_hook pool sizeAlasdair G Kergon2012-07-271-1/+1
| | | | | | | | | | | | | Reduce the slab size used for the dm_thin_endio_hook mempool. Allocation has been seen to fail on machines with smaller amounts of memory due to fragmentation. lvm: page allocation failure. order:5, mode:0xd0 device-mapper: table: 253:38: thin-pool: Error creating pool's endio_hook mempool Cc: stable@vger.kernel.org Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* Merge tag 'dm-3.5-fixes-2' of ↵Linus Torvalds2012-07-203-3/+11
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm Pull device-mapper discard fixes from Alasdair G Kergon: - avoid a crash in dm-raid1 when discards coincide with mirror recovery; - avoid discarding shared data that's still needed in dm-thin; - don't guarantee that discarded blocks will be wiped in dm-raid1. * tag 'dm-3.5-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: dm raid1: set discard_zeroes_data_unsupported dm thin: do not send discards to shared blocks dm raid1: fix crash with mirror recovery and discard
| * dm raid1: set discard_zeroes_data_unsupportedMikulas Patocka2012-07-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We can't guarantee that REQ_DISCARD on dm-mirror zeroes the data even if the underlying disks support zero on discard. So this patch sets ti->discard_zeroes_data_unsupported. For example, if the mirror is in the process of resynchronizing, it may happen that kcopyd reads a piece of data, then discard is sent on the same area and then kcopyd writes the piece of data to another leg. Consequently, the data is not zeroed. The flag was made available by commit 983c7db347db8ce2d8453fd1d89b7a4bb6920d56 (dm crypt: always disable discard_zeroes_data). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@kernel.org Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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