linux-toradex.git/drivers/md/persistent-data/dm-space-map-metadata.c, branch v5.0

dm space map metadata: use ARRAY_SIZE

2017-11-10T20:44:52+00:00

Using the ARRAY_SIZE macro improves the readability of the code.

Found with Coccinelle with the following semantic patch:
@r depends on (org || report)@
type T;
T[] E;
position p;
@@
(
 (sizeof(E)@p /sizeof(*E))
|
 (sizeof(E)@p /sizeof(E[...]))
|
 (sizeof(E)@p /sizeof(T))
)

Signed-off-by: Jérémy Lefaure 
Signed-off-by: Mike Snitzer

dm space map metadata: constify dm_space_map structures

2017-02-16T19:14:36+00:00

Declare dm_space_map structures as const as they are only passed as an
argument to the function memcpy. This argument is of type const void *,
so dm_space_map structures having this property can be declared as
const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   4889	    240	      0	   5129	   1409 dm-space-map-metadata.o

File size after:
   text	   data	    bss	    dec	    hex	filename
   5139	      0	      0	   5139	   1413 dm-space-map-metadata.o

Signed-off-by: Bhumika Goyal 
Signed-off-by: Mike Snitzer

dm space map metadata: fix 'struct sm_metadata' leak on failed create

2016-12-08T19:13:14+00:00

In dm_sm_metadata_create() we temporarily change the dm_space_map
operations from 'ops' (whose .destroy function deallocates the
sm_metadata) to 'bootstrap_ops' (whose .destroy function doesn't).

If dm_sm_metadata_create() fails in sm_ll_new_metadata() or
sm_ll_extend(), it exits back to dm_tm_create_internal(), which calls
dm_sm_destroy() with the intention of freeing the sm_metadata, but it
doesn't (because the dm_space_map operations is still set to
'bootstrap_ops').

Fix this by setting the dm_space_map operations back to 'ops' if
dm_sm_metadata_create() fails when it is set to 'bootstrap_ops'.

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

dm space map metadata: remove unused variable in brb_pop()

2015-12-14T14:26:01+00:00

Remove the unused struct block_op pointer that was inadvertantly
introduced, via cut-and-paste of previous brb_op() code, as part of
commit 50dd842ad.

(Cc'ing stable@ because commit 50dd842ad did)

Fixes: 50dd842ad ("dm space map metadata: fix ref counting bug when bootstrapping a new space map")
Reported-by: David Binderman 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org

dm space map metadata: fix ref counting bug when bootstrapping a new space map

2015-12-09T18:27:25+00:00

When applying block operations (BOPs) do not remove them from the
uncommitted BOP ring-buffer until after they've been applied -- in case
we recurse.

Also, perform BOP_INC operation, in dm_sm_metadata_create() and
sm_metadata_extend(), in terms of the uncommitted BOP ring-buffer rather
than using direct calls to sm_ll_inc().

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

dm space map metadata: fix occasional leak of a metadata block on resize

2015-06-17T14:09:23+00:00

The metadata space map has a simplified 'bootstrap' mode that is
operational when extending the space maps.  Whilst in this mode it's
possible for some refcount decrement operations to become queued (eg, as
a result of shadowing one of the bitmap indexes).  These decrements were
not being applied when switching out of bootstrap mode.

The effect of this bug was the leaking of a 4k metadata block.  This is
detected by the latest version of thin_check as a non fatal error.

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

dm space map metadata: fix sm_bootstrap_get_count()

2014-12-02T15:25:06+00:00

Must set 'result' accordingly rather than return it.

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

dm space map metadata: fix sm_bootstrap_get_nr_blocks()

2014-12-01T16:31:58+00:00

This function isn't right and it causes a static checker warning:

	drivers/md/dm-thin.c:3016 maybe_resize_data_dev()
	error: potentially using uninitialized 'sb_data_size'.

It should set "*count" and return zero on success the same as the
sm_metadata_get_nr_blocks() function does earlier.

Fixes: 3241b1d3e0aa ('dm: add persistent data library')
Signed-off-by: Dan Carpenter 
Acked-by: Joe Thornber 
Signed-off-by: Mike Snitzer

dm space map metadata: fix refcount decrement below 0 which caused corruption

2014-03-07T17:02:47+00:00

This has been a relatively long-standing issue that wasn't nailed down
until Teng-Feng Yang's meticulous bug report to dm-devel on 3/7/2014,
see: http://www.redhat.com/archives/dm-devel/2014-March/msg00021.html

From that report:
  "When decreasing the reference count of a metadata block with its
  reference count equals 3, we will call dm_btree_remove() to remove
  this enrty from the B+tree which keeps the reference count info in
  metadata device.

  The B+tree will try to rebalance the entry of the child nodes in each
  node it traversed, and the rebalance process contains the following
  steps.

  (1) Finding the corresponding children in current node (shadow_current(s))
  (2) Shadow the children block (issue BOP_INC)
  (3) redistribute keys among children, and free children if necessary (issue BOP_DEC)

  Since the update of a metadata block's reference count could be
  recursive, we will stash these reference count update operations in
  smm->uncommitted and then process them in a FILO fashion.

  The problem is that step(3) could free the children which is created
  in step(2), so the BOP_DEC issued in step(3) will be carried out
  before the BOP_INC issued in step(2) since these BOPs will be
  processed in FILO fashion. Once the BOP_DEC from step(3) tries to
  decrease the reference count of newly shadow block, it will report
  failure for its reference equals 0 before decreasing. It looks like we
  can solve this issue by processing these BOPs in a FIFO fashion
  instead of FILO."

Commit 5b564d80 ("dm space map: disallow decrementing a reference count
below zero") changed the code to report an error for this temporary
refcount decrement below zero.  So what was previously a harmless
invalid refcount became a hard failure due to the new error path:

 device-mapper: space map common: unable to decrement a reference count below 0
 device-mapper: thin: 253:6: dm_thin_insert_block() failed: error = -22
 device-mapper: thin: 253:6: switching pool to read-only mode

This bug is in dm persistent-data code that is common to the DM thin and
cache targets.  So any users of those targets should apply this fix.

Fix this by applying recursive space map operations in FIFO order rather
than FILO.

Resolves: https://bugzilla.kernel.org/show_bug.cgi?id=68801

Reported-by: Apollon Oikonomopoulos 
Reported-by: edwillam1007@gmail.com
Reported-by: Teng-Feng Yang 
Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # 3.13+

dm thin: allow metadata space larger than supported to go unused

2014-02-27T16:49:08+00:00

It was always intended that a user could provide a thin metadata device
that is larger than the max supported by the on-disk format.  The extra
space would just go unused.

Unfortunately that never worked.  If the user attempted to use a larger
metadata device on creation they would get an error like the following:

 device-mapper: space map common: space map too large
 device-mapper: transaction manager: couldn't create metadata space map
 device-mapper: thin metadata: tm_create_with_sm failed
 device-mapper: table: 252:17: thin-pool: Error creating metadata object
 device-mapper: ioctl: error adding target to table

Fix this by allowing the initial metadata space map creation to cap its
size at the max number of blocks supported (DM_SM_METADATA_MAX_BLOCKS).
get_metadata_dev_size() must also impose DM_SM_METADATA_MAX_BLOCKS (via
THIN_METADATA_MAX_SECTORS), otherwise extending metadata would cap at
THIN_METADATA_MAX_SECTORS_WARNING (which is larger than supported).

Also, the calculation for THIN_METADATA_MAX_SECTORS didn't account for
the sizeof the disk_bitmap_header.  So the supported maximum metadata
size is a bit smaller (reduced from 33423360 to 33292800 sectors).

Lastly, remove the "excess space will not be used" warning message from
get_metadata_dev_size(); it resulted in printing the warning multiple
times.  Factor out warn_if_metadata_device_too_big(), call it from
pool_ctr() and maybe_resize_metadata_dev().

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