linux-toradex.git/drivers/md/dm-snap.c, branch v2.6.34.8

dm snapshot: test chunk size against both origin and snapshot

2010-08-26T23:43:35+00:00

commit c24110450650f17f7d3ba4fbe01f01ac5a115456 upstream.

Validate chunk size against both origin and snapshot sector size

Don't allow chunk size smaller than either origin or snapshot logical
sector size. Reading or writing data not aligned to sector size is not
allowed and causes immediate errors.

This requires us to open the origin before initialising the
exception store and to export dm_snap_origin.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon 
Signed-off-by: Greg Kroah-Hartman

dm snapshot: iterate origin and cow devices

2010-08-26T23:43:35+00:00

commit 1e5554c8428bc7209a83e2d07ca724be4d981ce3 upstream.

Iterate both origin and snapshot devices

iterate_devices method should call the callback for all the devices where
the bio may be remapped. Thus, snapshot_iterate_devices should call the callback
for both snapshot and origin underlying devices because it remaps some bios
to the snapshot and some to the origin.

snapshot_iterate_devices called the callback only for the origin device.
This led to badly calculated device limits if snapshot and origin were placed
on different types of disks.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon 
Signed-off-by: Greg Kroah-Hartman

dm: eliminate some holes data structures

2010-03-06T02:32:33+00:00

Eliminate a 4-byte hole in 'struct dm_io_memory' by moving 'offset' above the
'ptr' to which it applies (size reduced from 24 to 16 bytes).  And by
association, 1-4 byte hole is eliminated in 'struct dm_io_request' (size
reduced from 56 to 48 bytes).

Eliminate all 6 4-byte holes and 1 cache-line in 'struct dm_snapshot' (size
reduced from 392 to 368 bytes).

Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm table: remove unused dm_get_device range parameters

2010-03-06T02:32:27+00:00

Remove unused parameters(start and len) of dm_get_device()
and fix the callers.

Signed-off-by: Nikanth Karthikesan 
Signed-off-by: Alasdair G Kergon

dm snapshot: use merge origin if snapshot invalid

2009-12-10T23:52:36+00:00

If the snapshot we are merging became invalid (e.g. it ran out of
space) redirect all I/O directly to the origin device.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm snapshot: report merge failure in status

2009-12-10T23:52:35+00:00

Set 'merge_failed' flag if a snapshot fails to merge.  Update
snapshot_status() to report "Merge failed" if 'merge_failed' is set.

Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm snapshot: merge consecutive chunks together

2009-12-10T23:52:34+00:00

s->store->type->prepare_merge returns the number of chunks that can be
copied linearly working backwards from the returned chunk number.

For example, if it returns 3 chunks with old_chunk == 10 and new_chunk
== 20, then chunk 20 can be copied to 10, chunk 19 to 9 and 18 to 8.

Until now kcopyd only copied one chunk at a time.  This patch now copies
the full set at once.

Consequently, snapshot_merge_process() needs to delay the merging of all
chunks if any have writes in progress, not just the first chunk in the
region that is to be merged.

snapshot-merge's performance is now comparable to the original
snapshot-origin target.

Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm snapshot: trigger exceptions in remaining snapshots during merge

2009-12-10T23:52:34+00:00

When there is one merging snapshot and other non-merging snapshots,
snapshot_merge_process() must make exceptions in the non-merging
snapshots.

Use a sequence count to resolve the race between I/O to chunks that are
about to be merged.  The count increases each time an exception
reallocation finishes.  Use wait_event() to wait until the count
changes.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm snapshot: delay merging a chunk until writes to it complete

2009-12-10T23:52:33+00:00

Track writes to chunks that are currently being merged and delay merging
a chunk until all writes to that chunk finish.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm snapshot: queue writes to chunks being merged

2009-12-10T23:52:33+00:00

While a set of chunks is being merged, any overlapping writes need to be
queued.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon