- 11 12月, 2009 17 次提交
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由 Mike Snitzer 提交于
Sets num_flush_requests=2 to support flushing both the origin and cow devices used by the snapshot-merge target. Also, snapshot_ctr() now gets the origin device using FMODE_WRITE if the target is snapshot-merge (which writes to the origin device). Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
The snapshot-merge target should not allocate new exceptions because the intent is to merge all of its exceptions as quickly and safely as possible. This patch introduces the snapshot-merge mapping function and updates __origin_write() so that it doesn't allocate exceptions on any snapshots that are being merged. If a write request to a merging snapshot device is to be dispatched directly to the origin (because the chunk is not remapped or was already merged), snapshot_merge_map() must make exceptions in other snapshots so calls do_origin(). Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
To track the completion of exceptions relating to the same location on the device, the current code selects one exception as primary_pe, links the other exceptions to it and uses reference counting to wait until all the reallocations are complete. It is considered too complicated to extend this code to handle the new snapshot-merge target, where sets of non-overlapping chunks would also need to become linked. Instead, a simpler (but less efficient) approach is taken. Bios are linked to one exception. When it completes, bios are simply retried, and if other related exceptions are still outstanding, they'll get queued again to wait for another one. Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
The snapshot-merge target allows a snapshot to be merged back into the snapshot's origin device. One anticipated use of snapshot merging is the rollback of filesystems to back out problematic system upgrades. This patch adds snapshot-merge target management to both dm_snapshot_init() and dm_snapshot_exit(). As an initial place-holder, snapshot-merge is identical to the snapshot target. Documentation is provided. Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
Move the __chunk_is_tracked() loop into a separate function as we will also need to call it from the write path in the rare case of conflicting writes to the same chunk. Originally introduced in commit a8d41b59 ("dm snapshot: fix race during exception creation"). Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
To support the merging of snapshots back into their origin we need to trigger exceptions in other snapshots not being merged without any incoming bio on the origin device. The bio parameter to __origin_write() becomes optional and the sector needs supplying separately. Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
Permit in-use snapshot exception data to be 'handed over' from one snapshot instance to another. This is a pre-requisite for patches that allow the changes made in a snapshot device to be merged back into its origin device and also allows device resizing. The basic call sequence is: dmsetup load new_snapshot (referencing the existing in-use cow device) - the ctr code detects that the cow is already in use and allows the two snapshot target instances to be linked together dmsetup suspend original_snapshot dmsetup resume new_snapshot - the new_snapshot becomes live, and if anything now tries to access the original one it will receive -EIO dmsetup remove original_snapshot (There can only be two snapshot targets referencing the same cow device simultaneously.) Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
Keep track of whether or not the device is suspended within the snapshot target module, the same as we do in dm-raid1. We will use this later to enforce the correct sequence of ioctls to transfer the in-core exceptions from a snapshot target instance in one table to a replacement one capable of merging them back into the origin. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com> Reviewed-by: NJonathan Brassow <jbrassow@redhat.com> Cc: Mikulas Patocka <mpatocka@redhat.com>
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由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jon Brassow 提交于
Rename exception functions. Preparing to pull them out of dm-snap.c for broader use. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Reviewed-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jon Brassow 提交于
Rename exception_table for broader use outside dm-snap.c Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Reviewed-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jon Brassow 提交于
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: NJonathan Brassow <jbrassow@redhat.com> Reviewed-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jon Brassow 提交于
Consolidate the insert_*exception functions. 'insert_completed_exception' already contains all the logic to handle 'insert_exception' (via check for a hash_shift of 0), so remove redundant function. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Reviewed-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
The origin needs to find minimum chunksize of all snapshots. This logic is moved to a separate function because it will be used at another place in the snapshot merge patches. Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Reviewed-by: NMike Snitzer <snitzer@redhat.com> Reviewed-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
Under some special conditions the snapshot hash_size is calculated as zero. This patch instead sets a minimum value of 64, the same as for the pending exception table. rounddown_pow_of_two(0) is an undefined operation (it expands to shift by -1). init_exception_table with an argument of 0 would fail with -ENOMEM. The way to trigger the problem is to create a snapshot with a chunk size that is larger than the origin device. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
Take snapshot lock only for STATUSTYPE_INFO, not STATUSTYPE_TABLE. Commit 4c6fff44 (dm-snapshot-lock-snapshot-while-supplying-status.patch) introduced this use of the lock, but userspace applications using libdevmapper have been found to request STATUSTYPE_TABLE while the device is suspended and the lock is already held, leading to deadlock. Since the lock is not necessary in this case, don't try to take it. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 17 10月, 2009 5 次提交
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由 Mikulas Patocka 提交于
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: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Reviewed-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
This patch locks the snapshot when returning status. It fixes a race when it could return an invalid number of free chunks if someone was simultaneously modifying it. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
If we are creating snapshot with memory-stored exception store, fail if the user didn't specify chunk size. Zero chunk size would probably crash a lot of places in the rest of snapshot code. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Reviewed-by: NJonathan Brassow <jbrassow@redhat.com> Reviewed-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
While initializing the snapshot module, if we fail to register the snapshot target then we must back-out the exception store module initialization. Cc: stable@kernel.org Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Reviewed-by: NMikulas Patocka <mpatocka@redhat.com> Reviewed-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
Avoid a race causing corruption when snapshots of the same origin have different chunk sizes by sorting the internal list of snapshots by chunk size, largest first. https://bugzilla.redhat.com/show_bug.cgi?id=182659 For example, let's have two snapshots with different chunk sizes. The first snapshot (1) has small chunk size and the second snapshot (2) has large chunk size. Let's have chunks A, B, C in these snapshots: snapshot1: ====A==== ====B==== snapshot2: ==========C========== (Chunk size is a power of 2. Chunks are aligned.) A write to the origin at a position within A and C comes along. It triggers reallocation of A, then reallocation of C and links them together using A as the 'primary' exception. Then another write to the origin comes along at a position within B and C. It creates pending exception for B. C already has a reallocation in progress and it already has a primary exception (A), so nothing is done to it: B and C are not linked. If the reallocation of B finishes before the reallocation of C, because there is no link with the pending exception for C it does not know to wait for it and, the second write is dispatched to the origin and causes data corruption in the chunk C in snapshot2. To avoid this situation, we maintain snapshots sorted in descending order of chunk size. This leads to a guaranteed ordering on the links between the pending exceptions and avoids the problem explained above - both A and B now get linked to C. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 05 9月, 2009 1 次提交
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由 Mike Snitzer 提交于
Implement the .iterate_devices for the origin and snapshot targets. dm-snapshot's lack of .iterate_devices resulted in the inability to properly establish queue_limits for both targets. With 4K sector drives: an unfortunate side-effect of not establishing proper limits in either targets' DM device was that IO to the devices would fail even though both had been created without error. Commit af4874e0 ("dm target:s introduce iterate devices fn") in 2.6.31-rc1 should have implemented .iterate_devices for dm-snap.c's origin and snapshot targets. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 22 6月, 2009 1 次提交
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由 Mikulas Patocka 提交于
Flush support for dm-snapshot target. This patch just forwards the flush request to either the origin or the snapshot device. (It doesn't flush exception store metadata.) Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 15 4月, 2009 1 次提交
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由 Christoph Hellwig 提交于
It's used by DM and MD and generally useful, so move the bio list helpers into bio.h. Signed-off-by: NChristoph Hellwig <hch@lst.de> Acked-by: NAlasdair G Kergon <agk@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 03 4月, 2009 13 次提交
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由 Jonathan Brassow 提交于
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: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
First step of having the exception stores parse their own arguments - generalizing the interface. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Use DMEMIT in place of snprintf. This makes it easier later when other modules are helping to populate our status output. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Move some of the last bits from dm-snap.h into dm-snap.c where they belong and remove dm-snap.h. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Move useful functions out of dm-snap.h and stop using dm-snap.h. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Move COW device from snapshot to exception store. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Move chunk fields from snapshot to exception store. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Move target pointer from snapshot to exception store. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Move exception stores into a registry. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Jonathan Brassow 提交于
Introduce struct dm_exception_store_type. Signed-off-by: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
We need to check if the exception was completed after dropping the lock. After regaining the lock, __find_pending_exception checks if the exception was already placed into &s->pending hash. But we don't check if the exception was already completed and placed into &s->complete hash. If the process waiting in alloc_pending_exception was delayed at this point because of a scheduling latency and the exception was meanwhile completed, we'd miss that and allocate another pending exception for already completed chunk. It would lead to a situation where two records for the same chunk exist and potential data corruption because multiple snapshot I/Os to the affected chunk could be redirected to different locations in the snapshot. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
It is uncommon and bug-prone to drop a lock in a function that is called with the lock held, so this is moved to the caller. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
Move looking-up of a pending exception from __find_pending_exception to another function. Cc: stable@kernel.org Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 06 1月, 2009 2 次提交
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由 Jonathan Brassow 提交于
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: NJonathan Brassow <jbrassow@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Alasdair G Kergon 提交于
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: NAlasdair G Kergon <agk@redhat.com>
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