linux.git/drivers/md/persistent-data/dm-block-manager.c, branch v4.10

dm block manager: make block locking optional

2016-11-14T20:17:47+00:00

The block manager's locking is useful for catching cycles that may
result from certain btree metadata corruption.  But in general it serves
as a developer tool to catch bugs in code.  Unless you're finding that
DM thin provisioning is hanging due to infinite loops within the block
manager's access to btree nodes you can safely disable this feature.

Signed-off-by: Joe Thornber 
Signed-off-by: Arnd Bergmann  # do/while(0) macro fix
Signed-off-by: Mike Snitzer

dm block manager: cleanup code that prints stacktrace

2015-12-10T15:38:56+00:00

There is no need to record stack trace and immediately print it.  Just
use dump_stack() to print the current stack.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer

dm persistent data: eliminate unnecessary return values

2015-10-31T23:06:02+00:00

dm_bm_unlock and dm_tm_unlock return an integer value but the returned
value is always 0.  The calling code sometimes checks the return value
and sometimes doesn't.

Eliminate these unnecessary return values and also the checks for them.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer

dm: remove unlikely() before IS_ERR()

2015-08-12T15:32:21+00:00

IS_ERR() already contains an 'unlikely' compiler flag so there is no
need to do that again from IS_ERR() callers.

Signed-off-by: Viresh Kumar 
Signed-off-by: Mike Snitzer

dm thin metadata: remove in-core 'read_only' flag

2015-05-29T18:18:59+00:00

Leverage the block manager's read_only flag instead of duplicating it;
access with new dm_bm_is_read_only() method.

Signed-off-by: Mike Snitzer

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