linux-stable.git/drivers/md/dm.c, branch linux-3.7.y

dm: fix deadlock with request based dm and queue request_fn recursion

2012-11-23T13:32:54+00:00

Request based dm attempts to re-run the request queue off the
request completion path. If used with a driver that potentially does
end_io from its request_fn, we could deadlock trying to recurse
back into request dispatch. Fix this by punting the request queue
run to kblockd.

Tested to fix a quickly reproducible deadlock in such a scenario.

Cc: stable@kernel.org
Acked-by: Alasdair G Kergon 
Signed-off-by: Jens Axboe

dm: store dm_target_io in bio front_pad

2012-10-12T20:02:15+00:00

Use the recently-added bio front_pad field to allocate struct dm_target_io.

Prior to this patch, dm_target_io was allocated from a mempool. For each
dm_target_io, there is exactly one bio allocated from a bioset.

This patch merges these two allocations into one allocation: we create a
bioset with front_pad equal to the size of dm_target_io so that every
bio allocated from the bioset has sizeof(struct dm_target_io) bytes
before it. We allocate a bio and use the bytes before the bio as
dm_target_io.

_tio_cache is removed and the tio_pool mempool is now only used for
request-based devices.

This idea was introduced by Kent Overstreet.

Signed-off-by: Mikulas Patocka 
Cc: Kent Overstreet 
Cc: Jens Axboe 
Cc: tj@kernel.org
Cc: Vivek Goyal 
Cc: Bill Pemberton 
Signed-off-by: Alasdair G Kergon

Merge branch 'for-3.7/core' of git://git.kernel.dk/linux-block

2012-10-11T00:04:23+00:00

Pull block IO update from Jens Axboe:
 "Core block IO bits for 3.7.  Not a huge round this time, it contains:

   - First series from Kent cleaning up and generalizing bio allocation
     and freeing.

   - WRITE_SAME support from Martin.

   - Mikulas patches to prevent O_DIRECT crashes when someone changes
     the block size of a device.

   - Make bio_split() work on data-less bio's (like trim/discards).

   - A few other minor fixups."

Fixed up silent semantic mis-merge as per Mikulas Patocka and Andrew
Morton.  It is due to the VM no longer using a prio-tree (see commit
6b2dbba8b6ac: "mm: replace vma prio_tree with an interval tree").

So make set_blocksize() use mapping_mapped() instead of open-coding the
internal VM knowledge that has changed.

* 'for-3.7/core' of git://git.kernel.dk/linux-block: (26 commits)
  block: makes bio_split support bio without data
  scatterlist: refactor the sg_nents
  scatterlist: add sg_nents
  fs: fix include/percpu-rwsem.h export error
  percpu-rw-semaphore: fix documentation typos
  fs/block_dev.c:1644:5: sparse: symbol 'blkdev_mmap' was not declared
  blockdev: turn a rw semaphore into a percpu rw semaphore
  Fix a crash when block device is read and block size is changed at the same time
  block: fix request_queue->flags initialization
  block: lift the initial queue bypass mode on blk_register_queue() instead of blk_init_allocated_queue()
  block: ioctl to zero block ranges
  block: Make blkdev_issue_zeroout use WRITE SAME
  block: Implement support for WRITE SAME
  block: Consolidate command flag and queue limit checks for merges
  block: Clean up special command handling logic
  block/blk-tag.c: Remove useless kfree
  block: remove the duplicated setting for congestion_threshold
  block: reject invalid queue attribute values
  block: Add bio_clone_bioset(), bio_clone_kmalloc()
  block: Consolidate bio_alloc_bioset(), bio_kmalloc()
  ...

dm: retain table limits when swapping to new table with no devices

2012-09-26T22:45:45+00:00

Add a safety net that will re-use the DM device's existing limits in the
event that DM device has a temporary table that doesn't have any
component devices.  This is to reduce the chance that requests not
respecting the hardware limits will reach the device.

DM recalculates queue limits based only on devices which currently exist
in the table.  This creates a problem in the event all devices are
temporarily removed such as all paths being lost in multipath.  DM will
reset the limits to the maximum permissible, which can then assemble
requests which exceed the limits of the paths when the paths are
restored.  The request will fail the blk_rq_check_limits() test when
sent to a path with lower limits, and will be retried without end by
multipath.  This became a much bigger issue after v3.6 commit fe86cdcef
("block: do not artificially constrain max_sectors for stacking
drivers").

Reported-by: David Jeffery 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm: handle requests beyond end of device instead of using BUG_ON

2012-09-26T22:45:42+00:00

The access beyond the end of device BUG_ON that was introduced to
dm_request_fn via commit 29e4013de7ad950280e4b2208 ("dm: implement
REQ_FLUSH/FUA support for request-based dm") was an overly
drastic (but simple) response to this situation.

I have received a report that this BUG_ON was hit and now think
it would be better to use dm_kill_unmapped_request() to fail the clone
and original request with -EIO.

map_request() will assign the valid target returned by
dm_table_find_target to tio->ti.  But when the target
isn't valid tio->ti is never assigned (because map_request isn't
called); so add a check for tio->ti != NULL to dm_done().

Reported-by: Mike Christie 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jun'ichi Nomura 
Cc: stable@vger.kernel.org # v2.6.37+
Signed-off-by: Alasdair G Kergon

block: Add bio_clone_bioset(), bio_clone_kmalloc()

2012-09-09T08:35:39+00:00

Previously, there was bio_clone() but it only allocated from the fs bio
set; as a result various users were open coding it and using
__bio_clone().

This changes bio_clone() to become bio_clone_bioset(), and then we add
bio_clone() and bio_clone_kmalloc() as wrappers around it, making use of
the functionality the last patch adedd.

This will also help in a later patch changing how bio cloning works.

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
CC: NeilBrown 
CC: Alasdair Kergon 
CC: Boaz Harrosh 
CC: Jeff Garzik 
Acked-by: Jeff Garzik 
Signed-off-by: Jens Axboe

dm: Use bioset's front_pad for dm_rq_clone_bio_info

2012-09-09T08:35:38+00:00

Previously, dm_rq_clone_bio_info needed to be freed by the bio's
destructor to avoid a memory leak in the blk_rq_prep_clone() error path.
This gets rid of a memory allocation and means we can kill
dm_rq_bio_destructor.

The _rq_bio_info_cache kmem cache is unused now and needs to be deleted,
but due to the way io_pool is used and overloaded this looks not quite
trivial so I'm leaving it for a later patch.

v6: Fix comment on struct dm_rq_clone_bio_info, per Tejun

Signed-off-by: Kent Overstreet 
CC: Alasdair Kergon 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

block: Ues bi_pool for bio_integrity_alloc()

2012-09-09T08:35:38+00:00

Now that bios keep track of where they were allocated from,
bio_integrity_alloc_bioset() becomes redundant.

Remove bio_integrity_alloc_bioset() and drop bio_set argument from the
related functions and make them use bio->bi_pool.

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
CC: Martin K. Petersen 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

block: Generalized bio pool freeing

2012-09-09T08:35:38+00:00

With the old code, when you allocate a bio from a bio pool you have to
implement your own destructor that knows how to find the bio pool the
bio was originally allocated from.

This adds a new field to struct bio (bi_pool) and changes
bio_alloc_bioset() to use it. This makes various bio destructors
unnecessary, so they're then deleted.

v6: Explain the temporary if statement in bio_put

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
CC: NeilBrown 
CC: Alasdair Kergon 
CC: Nicholas Bellinger 
CC: Lars Ellenberg 
Acked-by: Tejun Heo 
Acked-by: Nicholas Bellinger 
Signed-off-by: Jens Axboe

dm: introduce split_discard_requests

2012-07-27T14:08:03+00:00

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 
Signed-off-by: Alasdair G Kergon