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* dm bufio: move dm-bufio.h to include/linux/Mikulas Patocka2018-04-031-1/+1
| | | | | | | | | | | | | | | | Move dm-bufio.h to include/linux/ so that external GPL'd DM target modules can use it. It is better to allow the use of dm-bufio than force external modules to implement the equivalent buffered IO mechanism in some new way. The hope is this will encourage the use of dm-bufio; which will then make it easier for a GPL'd external DM target module to be included upstream. A couple dm-bufio EXPORT_SYMBOL exports have also been updated to use EXPORT_SYMBOL_GPL. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm: make flush bios explicitly syncJan Kara2017-05-311-1/+2
| | | | | | | | | | | | | | | | | Commit b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous") removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...} definitions. generic_make_request_checks() however strips REQ_FUA and REQ_PREFLUSH flags from a bio when the storage doesn't report volatile write cache and thus write effectively becomes asynchronous which can lead to performance regressions. Fix the problem by making sure all bios which are synchronous are properly marked with REQ_SYNC. Fixes: b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous") Cc: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* block,fs: use REQ_* flags directlyChristoph Hellwig2016-11-011-2/+2
| | | | | | | | | Remove the WRITE_* and READ_SYNC wrappers, and just use the flags directly. Where applicable this also drops usage of the bio_set_op_attrs wrapper. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* dm: use bio op accessorsMike Christie2016-06-071-11/+13
| | | | | | | | | Separate the op from the rq_flag_bits and have dm set/get the bio using bio_set_op_attrs/bio_op. Signed-off-by: Mike Christie <mchristi@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* dm snapshot: fix hung bios when copy error occursMikulas Patocka2016-01-091-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When there is an error copying a chunk dm-snapshot can incorrectly hold associated bios indefinitely, resulting in hung IO. The function copy_callback sets pe->error if there was error copying the chunk, and then calls complete_exception. complete_exception calls pending_complete on error, otherwise it calls commit_exception with commit_callback (and commit_callback calls complete_exception). The persistent exception store (dm-snap-persistent.c) assumes that calls to prepare_exception and commit_exception are paired. persistent_prepare_exception increases ps->pending_count and persistent_commit_exception decreases it. If there is a copy error, persistent_prepare_exception is called but persistent_commit_exception is not. This results in the variable ps->pending_count never returning to zero and that causes some pending exceptions (and their associated bios) to be held forever. Fix this by unconditionally calling commit_exception regardless of whether the copy was successful. A new "valid" parameter is added to commit_exception -- when the copy fails this parameter is set to zero so that the chunk that failed to copy (and all following chunks) is not recorded in the snapshot store. Also, remove commit_callback now that it is merely a wrapper around pending_complete. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
* Merge tag 'dm-4.4-changes' of ↵Linus Torvalds2015-11-051-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: convert ffs to __ffsMikulas Patocka2015-11-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | ffs counts bit starting with 1 (for the least significant bit), __ffs counts bits starting with 0. This patch changes various occurrences of ffs to __ffs and removes subtraction of 1 from the result. Note that __ffs (unlike ffs) is not defined when called with zero argument, but it is not called with zero argument in any of these cases. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* | dm snapshot persistent: fix missing cleanup in persistent_ctr error pathSudip Mukherjee2015-10-131-3/+12
| | | | | | | | | | | | | | | | | | | | If an unsupported option is given then the early return from persistent_ctr() leaked memory allocated for the 'pstore' and never destroyed the 'metadata_wq'. Fixes: b0d3cc011e53 ("dm snapshot: add new persistent store option to support overflow") Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* | dm snapshot: add new persistent store option to support overflowMike Snitzer2015-10-091-3/+14
|/ | | | | | | | | | | | | | | Commit 76c44f6d80 introduced the possibly for "Overflow" to be reported by the snapshot device's status. Older userspace (e.g. lvm2) does not handle the "Overflow" status response. Fix this incompatibility by requiring newer userspace code, that can cope with "Overflow", request the persistent store with overflow support by using "PO" (Persistent with Overflow) for the snapshot store type. Reported-by: Zdenek Kabelac <zkabelac@redhat.com> Fixes: 76c44f6d80 ("dm snapshot: don't invalidate on-disk image on snapshot write overflow") Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm: remove unlikely() before IS_ERR()viresh kumar2015-08-121-1/+1
| | | | | | | | IS_ERR() already contains an 'unlikely' compiler flag so there is no need to do that again from IS_ERR() callers. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm snapshot: remove unnecessary NULL checks before vfree() callsMarkus Elfring2015-02-091-10/+4
| | | | | | | | | | The vfree() function performs input parameter validation. Thus the NULL pointer test around vfree() calls is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm snapshot: fix metadata corruptionMikulas Patocka2014-03-031-0/+3
| | | | | | | | | | | | | | | | | | Commit 55494bf2947dccdf2 ("dm snapshot: use dm-bufio") broke snapshots. Before that 3.14-rc1 commit, loading a snapshot's list of exceptions involved reading exception areas one by one into ps->area and inserting those exceptions into the hash table. Commit 55494bf2947dccdf2 changed it so that dm-bufio with prefetch is used to load exceptions in batchs. Exceptions are loaded correctly, but ps->area is left uninitialized. When a new exception is allocated, it is stored in this uninitialized ps->area which will be written to the disk. This causes metadata corruption. Fix this corruption by copying the last area that was read via dm-bufio into ps->area. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm snapshot: use dm-bufio prefetchMikulas Patocka2014-01-151-1/+24
| | | | | | | | | | | | | | | | | | | | This patch modifies dm-snapshot so that it prefetches the buffers when loading the exceptions. The number of buffers read ahead is specified in the DM_PREFETCH_CHUNKS macro. The current value for DM_PREFETCH_CHUNKS (12) was found to provide the best performance on a single 15k SCSI spindle. In the future we may modify this default or make it configurable. Also, introduce the function dm_bufio_set_minimum_buffers to setup bufio's number of internal buffers before freeing happens. dm-bufio may hold more buffers if enough memory is available. There is no guarantee that the specified number of buffers will be available - if you need a guarantee, use the argument reserved_buffers for dm_bufio_client_create. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm snapshot: use dm-bufioMikulas Patocka2014-01-151-7/+32
| | | | | | | | Use dm-bufio for initial loading of the exceptions. Introduce a new function dm_bufio_forget that frees the given buffer. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm snapshot: prepare for switch to using dm-bufioMikulas Patocka2014-01-141-12/+14
| | | | | | | | | | | Change the functions get_exception, read_exception and insert_exceptions so that ps->area is passed as an argument. This patch doesn't change any functionality, but it refactors the code to allow for a cleaner switch over to using dm-bufio. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm snapshot: call destroy_work_on_stack() to pair with INIT_WORK_ONSTACK()Chuansheng Liu2014-01-071-0/+1
| | | | | | | | | In case CONFIG_DEBUG_OBJECTS_WORK is defined, it is needed to call destroy_work_on_stack() which frees the debug object to pair with INIT_WORK_ONSTACK(). Signed-off-by: Liu, Chuansheng <chuansheng.liu@intel.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm snapshot: fix data corruptionMikulas Patocka2013-10-161-6/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes a particular type of data corruption that has been encountered when loading a snapshot's metadata from disk. When we allocate a new chunk in persistent_prepare, we increment ps->next_free and we make sure that it doesn't point to a metadata area by further incrementing it if necessary. When we load metadata from disk on device activation, ps->next_free is positioned after the last used data chunk. However, if this last used data chunk is followed by a metadata area, ps->next_free is positioned erroneously to the metadata area. A newly-allocated chunk is placed at the same location as the metadata area, resulting in data or metadata corruption. This patch changes the code so that ps->next_free skips the metadata area when metadata are loaded in function read_exceptions. The patch also moves a piece of code from persistent_prepare_exception to a separate function skip_metadata to avoid code duplication. CVE-2013-4299 Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Cc: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: workaround for a false positive lockdep warningMikulas Patocka2013-09-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | The kernel reports a lockdep warning if a snapshot is invalidated because it runs out of space. The lockdep warning was triggered by commit 0976dfc1d0cd80a4e9dfaf87bd87 ("workqueue: Catch more locking problems with flush_work()") in v3.5. The warning is false positive. The real cause for the warning is that the lockdep engine treats different instances of md->lock as a single lock. This patch is a workaround - we use flush_workqueue instead of flush_work. This code path is not performance sensitive (it is called only on initialization or invalidation), thus it doesn't matter that we flush the whole workqueue. The real fix for the problem would be to teach the lockdep engine to treat different instances of md->lock as separate locks. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Acked-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # 3.5+
* md: Add in export.h for files using EXPORT_SYMBOLPaul Gortmaker2011-11-011-0/+1
| | | | | | | | These files were getting the defines for EXPORT_SYMBOL because device.h was including module.h. But we are going to put an end to that. So add the proper export.h include now. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
* dm snapshot: style cleanupsJonathan Brassow2011-08-021-2/+2
| | | | | | | Coding style cleanups. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
* dm: use vzallocJoe Perches2011-08-021-2/+1
| | | | | | | Use vzalloc() instead of vmalloc()+memset(). Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: suppress endian warningsAlasdair G Kergon2011-08-021-33/+38
| | | | | | | Suppress sparse warnings about cpu_to_le32() by using __le32 types for on-disk data etc. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: flush disk cache when mergingMikulas Patocka2011-08-021-1/+1
| | | | | | | | | | | | | This patch makes dm-snapshot flush disk cache when writing metadata for merging snapshot. Without cache flushing the disk may reorder metadata write and other data writes and there is a possibility of data corruption in case of power fault. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm io: use fixed initial mempool sizeMikulas Patocka2011-05-291-12/+1
| | | | | | | | | | | | | | | | | Replace the arbitrary calculation of an initial io struct mempool size with a constant. The code calculated the number of reserved structures based on the request size and used a "magic" multiplication constant of 4. This patch changes it to reserve a fixed number - itself still chosen quite arbitrarily. Further testing might show if there is a better number to choose. Note that if there is no memory pressure, we can still allocate an arbitrary number of "struct io" structures. One structure is enough to process the whole request. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: persistent make metadata_wq multithreadedTejun Heo2011-01-131-2/+2
| | | | | | | | | | | | | | metadata_wq serves on-stack work items from chunk_io(). Even if multiple chunk_io() are simultaneously in progress, each is independent and queued only once, so multithreaded workqueue can be safely used. Switch metadata_wq to multithread and flush the work item instead of the workqueue in chunk_io(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: convert workqueues to alloc_orderedTejun Heo2011-01-131-1/+1
| | | | | | | | | | Convert all create[_singlethread]_work() users to the new alloc[_ordered]_workqueue(). This conversion is mechanical and doesn't introduce any behavior change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* workqueues: s/ON_STACK/ONSTACK/Andrew Morton2010-10-271-1/+1
| | | | | | | | | | | | | | | Silly though it is, completions and wait_queue_heads use foo_ONSTACK (COMPLETION_INITIALIZER_ONSTACK, DECLARE_COMPLETION_ONSTACK, __WAIT_QUEUE_HEAD_INIT_ONSTACK and DECLARE_WAIT_QUEUE_HEAD_ONSTACK) so I guess workqueues should do the same thing. s/INIT_WORK_ON_STACK/INIT_WORK_ONSTACK/ s/INIT_DELAYED_WORK_ON_STACK/INIT_DELAYED_WORK_ONSTACK/ Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dm: implement REQ_FLUSH/FUA support for bio-based dmTejun Heo2010-09-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch converts bio-based dm to support REQ_FLUSH/FUA instead of now deprecated REQ_HARDBARRIER. * -EOPNOTSUPP handling logic dropped. * Preflush is handled as before but postflush is dropped and replaced with passing down REQ_FUA to member request_queues. This replaces one array wide cache flush w/ member specific FUA writes. * __split_and_process_bio() now calls __clone_and_map_flush() directly for flushes and guarantees all FLUSH bio's going to targets are zero ` length. * It's now guaranteed that all FLUSH bio's which are passed onto dm targets are zero length. bio_empty_barrier() tests are replaced with REQ_FLUSH tests. * Empty WRITE_BARRIERs are replaced with WRITE_FLUSHes. * Dropped unlikely() around REQ_FLUSH tests. Flushes are not unlikely enough to be marked with unlikely(). * Block layer now filters out REQ_FLUSH/FUA bio's if the request_queue doesn't support cache flushing. Advertise REQ_FLUSH | REQ_FUA capability. * Request based dm isn't converted yet. dm_init_request_based_queue() resets flush support to 0 for now. To avoid disturbing request based dm code, dm->flush_error is added for bio based dm while requested based dm continues to use dm->barrier_error. Lightly tested linear, stripe, raid1, snap and crypt targets. Please proceed with caution as I'm not familiar with the code base. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: dm-devel@redhat.com Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* dm snapshot: persistent use define for disk header chunk sizeTomohiro Kusumi2010-08-121-3/+3
| | | | | | | | | | This patch fixes hard-coded value for the size of a chunk that includes disk header for persistent snapshot. It should be changed to existing macro NUM_SNAPSHOT_HDR_CHUNKS instead of using hard-coded value 1. Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@jp.fujitsu.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: persistent annotate work_queue as on stackMike Snitzer2010-02-161-1/+1
| | | | | | | | | | chunk_io() declares its 'struct mdata_req' on the stack and then initializes its 'struct work_struct' member. Annotate the initialization of this workqueue with INIT_WORK_ON_STACK to suppress a debugobjects warning seen when CONFIG_DEBUG_OBJECTS_WORK is enabled. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm exception store: add merge specific methodsMikulas Patocka2009-12-111-2/+112
| | | | | | | | | | | | | | | | | | | | Add functions that decide how many consecutive chunks of snapshot to merge back into the origin next and to update the metadata afterwards. prepare_merge provides a pointer to the most recent still-to-be-merged chunk and returns how many previous ones are consecutive and can be processed together. commit_merge removes the nr_merged most-recent chunks permanently from the exception store. The number must not exceed that returned by prepare_merge. Introduce NUM_SNAPSHOT_HDR_CHUNKS to show where the snapshot header chunk is accounted for. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: move cow ref from exception store to snap coreMike Snitzer2009-12-111-6/+6
| | | | | | | | | | | | | | Store the reference to the snapshot cow device in the core snapshot code instead of each exception store. It can be accessed through the new function dm_snap_cow(). Exception stores should each now maintain a reference to their parent snapshot struct. This is cleaner and makes part of the forthcoming snapshot merge code simpler. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Reviewed-by: Jonathan Brassow <jbrassow@redhat.com> Cc: Mikulas Patocka <mpatocka@redhat.com>
* dm snapshot: add allocated metadata to snapshot statusMike Snitzer2009-12-111-6/+17
| | | | | | | | | | | | Add number of sectors used by metadata to the end of the snapshot's status line. Renamed dm_exception_store_type's 'fraction_full' to 'usage'. Renamed arguments to be clearer about what is being returned. Also added 'metadata_sectors'. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: rename dm_snap_exception to dm_exceptionJon Brassow2009-12-111-2/+2
| | | | | | | | | | | The exception structure is not necessarily just a snapshot element (especially after we pull it out of dm-snap.c). Renaming appropriately. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: avoid else clause in persistent_read_metadataJon Brassow2009-12-111-25/+21
| | | | | | | | | Minor code touch-up. We don't need the 'else'. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: use unsigned integer chunk sizeMikulas Patocka2009-10-171-8/+8
| | | | | | | | | | | | | | Use unsigned integer chunk size. Maximum chunk size is 512kB, there won't ever be need to use 4GB chunk size, so the number can be 32-bit. This fixes compiler failure on 32-bit systems with large block devices. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: fix on disk chunk size validationMikulas Patocka2009-09-041-8/+14
| | | | | | | | | | | | | | | | | | | | | | | Fix some problems seen in the chunk size processing when activating a pre-existing snapshot. For a new snapshot, the chunk size can either be supplied by the creator or a default value can be used. For an existing snapshot, the chunk size in the snapshot header on disk should always be used. If someone attempts to load an existing snapshot and has the 'default chunk size' option set, the kernel uses its default value even when it is incorrect for the snapshot being loaded. This patch ensures the correct on-disk value is always used. Secondly, when the code does use the chunk size stored on the disk it is prudent to revalidate it, so the code can exit cleanly if it got corrupted as happened in https://bugzilla.redhat.com/show_bug.cgi?id=461506 . Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: fix header corruption race on invalidationMikulas Patocka2009-09-041-10/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a persistent snapshot fills up, a race can corrupt the on-disk header which causes a crash on any future attempt to activate the snapshot (typically while booting). This patch fixes the race. When the snapshot overflows, __invalidate_snapshot is called, which calls snapshot store method drop_snapshot. It goes to persistent_drop_snapshot that calls write_header. write_header constructs the new header in the "area" location. Concurrently, an existing kcopyd job may finish, call copy_callback and commit_exception method, that goes to persistent_commit_exception. persistent_commit_exception doesn't do locking, relying on the fact that callbacks are single-threaded, but it can race with snapshot invalidation and overwrite the header that is just being written while the snapshot is being invalidated. The result of this race is a corrupted header being written that can lead to a crash on further reactivation (if chunk_size is zero in the corrupted header). The fix is to use separate memory areas for each. See the bug: https://bugzilla.redhat.com/show_bug.cgi?id=461506 Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: refactor zero_disk_area to use chunk_ioMikulas Patocka2009-09-041-19/+7
| | | | | | | | | | | Refactor chunk_io to prepare for the fix in the following patch. Pass an area pointer to chunk_io and simplify zero_disk_area to use chunk_io. No functional change. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: use barrier when writing exception storeMikulas Patocka2009-06-221-1/+1
| | | | | | | | | | Send barrier requests when updating the exception area. Exception area updates need to be ordered w.r.t. data writes, so that the writes are not reordered in hardware disk cache. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* block: Do away with the notion of hardsect_sizeMartin K. Petersen2009-05-221-1/+1
| | | | | | | | | | | | | | Until now we have had a 1:1 mapping between storage device physical block size and the logical block sized used when addressing the device. With SATA 4KB drives coming out that will no longer be the case. The sector size will be 4KB but the logical block size will remain 512-bytes. Hence we need to distinguish between the physical block size and the logical ditto. This patch renames hardsect_size to logical_block_size. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* dm snapshot: persistent fix dtr cleanupJonathan Brassow2009-04-021-5/+15
| | | | | | | | | | | The persistent exception store destructor does not properly account for all conditions in which it can be called. If it is called after 'ctr' but before 'read_metadata' (e.g. if something else in 'snapshot_ctr' fails) then it will attempt to free areas of memory that haven't been allocated yet. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: move status to exception storeJonathan Brassow2009-04-021-4/+12
| | | | | | | | | | | Let the exception store types print out their status through the new API, rather than having the snapshot code do it. Adjust the buffer position to allow for the preceding DMEMIT in the arguments to type->status(). Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: remove dm_snap header useJonathan Brassow2009-04-021-29/+27
| | | | | | | Move useful functions out of dm-snap.h and stop using dm-snap.h. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm exception store: move cow pointerJonathan Brassow2009-04-021-5/+5
| | | | | | | Move COW device from snapshot to exception store. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm exception store: move chunk_fieldsJonathan Brassow2009-04-021-23/+24
| | | | | | | Move chunk fields from snapshot to exception store. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm exception store: introduce registryJonathan Brassow2009-04-021-10/+57
| | | | | | | Move exception stores into a registry. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm exception store: separate type from instanceJonathan Brassow2009-04-021-6/+7
| | | | | | | Introduce struct dm_exception_store_type. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: extend exception store functionsJonathan Brassow2009-01-061-16/+26
| | | | | | | | | Supply dm_add_exception as a callback to the read_metadata function. Add a status function ready for a later patch and name the functions consistently. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: split out exception store implementationsAlasdair G Kergon2009-01-061-0/+694
Move the existing snapshot exception store implementations out into separate files. Later patches will place these behind a new interface in preparation for alternative implementations. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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