linux-toradex.git/drivers/md/persistent-data/dm-block-manager.c, branch v3.18-rc5

dm transaction manager: fix corruption due to non-atomic transaction commit

2014-03-27T20:56:23+00:00

The persistent-data library used by dm-thin, dm-cache, etc is
transactional.  If anything goes wrong, such as an io error when writing
new metadata or a power failure, then we roll back to the last
transaction.

Atomicity when committing a transaction is achieved by:

a) Never overwriting data from the previous transaction.
b) Writing the superblock last, after all other metadata has hit the
   disk.

This commit and the following commit ("dm: take care to copy the space
map roots before locking the superblock") fix a bug associated with (b).
When committing it was possible for the superblock to still be written
in spite of an io error occurring during the preceeding metadata flush.
With these commits we're careful not to take the write lock out on the
superblock until after the metadata flush has completed.

Change the transaction manager's semantics for dm_tm_commit() to assume
all data has been flushed _before_ the single superblock that is passed
in.

As a prerequisite, split the block manager's block unlocking and
flushing by simplifying dm_bm_flush_and_unlock() to dm_bm_flush().  Now
the unlocking must be done separately.

This issue was discovered by forcing io errors at the crucial time
using dm-flakey.

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org

dm persistent data: cleanup dm-thin specific references in text

2014-01-07T15:11:54+00:00

DM's persistent-data library is now used my multiple targets so
exclusive references to "pool" or "thin provisioning" need to be
cleaned up.  Adjust Kconfig's DM_DEBUG_BLOCK_STACK_TRACING text
and remove "pool" from a block manager error message.

Signed-off-by: Mike Snitzer 
Acked-by: Joe Thornber

dm thin: allow pool in read-only mode to transition to read-write mode

2013-12-10T21:35:13+00:00

A thin-pool may be in read-only mode because the pool's data or metadata
space was exhausted.  To allow for recovery, by adding more space to the
pool, we must allow a pool to transition from PM_READ_ONLY to PM_WRITE
mode.  Otherwise, running out of space will render the pool permanently
read-only.

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org

dm btree: prefetch child nodes when walking tree for a dm_btree_del

2013-08-23T13:02:14+00:00

dm-btree now takes advantage of dm-bufio's ability to prefetch data via
dm_bm_prefetch().  Prior to this change many btree node visits were
causing a synchronous read.

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

dm: add cache target

2013-03-01T22:45:51+00:00

Add a target that allows a fast device such as an SSD to be used as a
cache for a slower device such as a disk.

A plug-in architecture was chosen so that the decisions about which data
to migrate and when are delegated to interchangeable tunable policy
modules.  The first general purpose module we have developed, called
"mq" (multiqueue), follows in the next patch.  Other modules are
under development.

Signed-off-by: Joe Thornber 
Signed-off-by: Heinz Mauelshagen 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

Merge tag 'dm-3.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

2012-12-22T01:08:06+00:00

Pull dm update from Alasdair G Kergon:
 "Miscellaneous device-mapper fixes, cleanups and performance
  improvements.

  Of particular note:
   - Disable broken WRITE SAME support in all targets except linear and
     striped.  Use it when kcopyd is zeroing blocks.
   - Remove several mempools from targets by moving the data into the
     bio's new front_pad area(which dm calls 'per_bio_data').
   - Fix a race in thin provisioning if discards are misused.
   - Prevent userspace from interfering with the ioctl parameters and
     use kmalloc for the data buffer if it's small instead of vmalloc.
   - Throttle some annoying error messages when I/O fails."

* tag 'dm-3.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: (36 commits)
  dm stripe: add WRITE SAME support
  dm: remove map_info
  dm snapshot: do not use map_context
  dm thin: dont use map_context
  dm raid1: dont use map_context
  dm flakey: dont use map_context
  dm raid1: rename read_record to bio_record
  dm: move target request nr to dm_target_io
  dm snapshot: use per_bio_data
  dm verity: use per_bio_data
  dm raid1: use per_bio_data
  dm: introduce per_bio_data
  dm kcopyd: add WRITE SAME support to dm_kcopyd_zero
  dm linear: add WRITE SAME support
  dm: add WRITE SAME support
  dm: prepare to support WRITE SAME
  dm ioctl: use kmalloc if possible
  dm ioctl: remove PF_MEMALLOC
  dm persistent data: improve improve space map block alloc failure message
  dm thin: use DMERR_LIMIT for errors
  ...

dm persistent data: use DMERR_LIMIT for errors

2012-12-21T20:23:34+00:00

Nearly all of persistent-data is in the IO path so throttle error
messages with DMERR_LIMIT to limit the amount logged when
something has gone wrong.

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

dm block manager: reinstate message when validator fails

2012-12-21T20:23:34+00:00

Reinstate a useful error message when the block manager buffer validator fails.
This was mistakenly eliminated when the block manager was converted to use
dm-bufio.

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

md: Fix typo in drivers/md

2012-10-29T21:57:50+00:00

Correct spelling typo in drivers/md.

Signed-off-by: Masanari Iida 
Signed-off-by: Jiri Kosina

dm persistent data: introduce dm_bm_set_read_only

2012-07-27T14:08:15+00:00

Introduce dm_bm_set_read_only to switch the block manager into a
read-only mode.  To be used when dm-thin degrades due to io errors on
the metadata device.

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