kernel/linux.git/drivers/md/dm-snap.c, branch linux-2.6.18.y

[PATCH] dm snapshot: fix freeing pending exception

2006-12-17T00:20:47+00:00

Fix oops when removing full snapshot kernel bugzilla bug 7040 If a snapshot became invalid (full) while there is outstanding pending_exception, pending_complete() forgets to remove the corresponding exception from its exception table before freeing it. Already fixed in 2.6.19. Signed-off-by: Milan Broz Signed-off-by: Chris Wright

Remove obsolete #include

2006-06-30T17:25:36+00:00

Signed-off-by: Jörn Engel Signed-off-by: Adrian Bunk

[PATCH] dm: improve error message consistency

2006-06-26T16:58:36+00:00

Tidy device-mapper error messages to include context information automatically. Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] dm snapshot: unify chunk_size

2006-06-26T16:58:34+00:00

Persistent snapshots currently store a private copy of the chunk size. Userspace also supplies the chunk size when loading a snapshot. Ensure consistency by only storing the chunk_size in one place instead of two. Currently the two sizes will differ if the chunk size supplied by userspace does not match the chunk size an existing snapshot actually uses. Amongst other problems, this causes an incorrect 'percentage full' to be reported. The patch ensures consistency by only storing the chunk_size in one place, removing it from struct pstore. Some initialisation is delayed until the correct chunk_size is known. If read_header() discovers that the wrong chunk size was supplied, the 'area' buffer (which the header already got read into) is reinitialised to the correct size. [akpm: too late for 2.6.17 - suitable for 2.6.17.x after it has settled] Signed-off-by: Alasdair G Kergon Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] dm snapshot: fix kcopyd destructor

2006-03-27T16:44:59+00:00

Before removing a snapshot, wait for the completion of any kcopyd jobs using it. Do this by maintaining a count (nr_jobs) of how many outstanding jobs each kcopyd_client has. The snapshot destructor first unregisters the snapshot so that no new kcopyd jobs (created by writes to the origin) will reference that particular snapshot. kcopyd_client_destroy() is now run next to wait for the completion of any outstanding jobs before the snapshot exception structures (that those jobs reference) are freed. Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] dm: remove SECTOR_FORMAT

2006-03-27T16:44:58+00:00

We don't know what type sector_t has. Sometimes it's unsigned long, sometimes it's unsigned long long. For example on ppc64 it's unsigned long with CONFIG_LBD=n and on x86_64 it's unsigned long long with CONFIG_LBD=n. The way to handle all of this is to always use unsigned long long and to always typecast the sector_t when printing it. Acked-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] device-mapper snapshot: fix invalidation

2006-03-27T16:44:58+00:00

When a snapshot becomes invalid, s->valid is set to 0. In this state, a snapshot can no longer be accessed. When s->lock is acquired, before doing anything else, s->valid must be checked to ensure the snapshot remains valid. This patch eliminates some races (that may cause panics) by adding some missing checks. At the same time, some unnecessary levels of indentation are removed and snapshot invalidation is moved into a single function that always generates a device-mapper event. Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] device-mapper snapshot: replace sibling list

2006-03-27T16:44:58+00:00

The siblings "list" is used unsafely at the moment. Firstly, only the element on the list being changed gets locked (via the snapshot lock), not the next and previous elements which have pointers that are also being changed. Secondly, if you have two or more snapshots and write to the same chunk a second time before every snapshot has finished making its private copy of the data, if you're unlucky, _origin_write() could attempt its list_merge() and dereference a 'last' pointer to a pending_exception structure that has just been freed. Analysis reveals that the list is actually only there for reference counting. If 5 pending_exceptions are needed in origin_write, then the 5 are joined together into a 5-element list - without a separate list head because there's nowhere suitable to store it. As the pending_exceptions complete, they are removed from the list one-by-one and any contents of origin_bios get moved across to one of the remaining pending_exceptions on the list. Whichever one is last is detected because list_empty() is then true and the origin_bios get submitted. The fix proposed here uses an alternative reference counting mechanism by choosing one of the pending_exceptions as primary and maintaining an atomic counter there. Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] device-mapper snapshot: fix origin_write pending_exception submission

2006-03-27T16:44:58+00:00

Say you have several snapshots of the same origin and then you issue a write to some place in the origin for the first time. Before the device-mapper snapshot target lets the write go through to the underlying device, it needs to make a copy of the data that is about to be overwritten. Each snapshot is independent, so it makes one copy for each snapshot. __origin_write() loops through each snapshot and checks to see whether a copy is needed for that snapshot. (A copy is only needed the first time that data changes.) If a copy is needed, the code allocates a 'pending_exception' structure holding the details. It links these together for all the snapshots, then works its way through this list and submits the copying requests to the kcopyd thread by calling start_copy(). When each request is completed, the original pending_exception structure gets freed in pending_complete(). If you're very unlucky, this structure can get freed *before* the submission process has finished walking the list. This patch: 1) Creates a new temporary list pe_queue to hold the pending exception structures; 2) Does all the bookkeeping up-front, then walks through the new list safely and calls start_copy() for each pending_exception that needed it; 3) Avoids attempting to add pe->siblings to the list if it's already connected. [NB This does not fix all the races in this code. More patches will follow.] Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] mempool: use mempool_create_slab_pool()

2006-03-26T16:57:00+00:00

Modify well over a dozen mempool users to call mempool_create_slab_pool() rather than calling mempool_create() with extra arguments, saving about 30 lines of code and increasing readability. Signed-off-by: Matthew Dobson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds