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path: root/drivers/md/persistent-data/dm-block-manager.h
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2015-10-31dm persistent data: eliminate unnecessary return valuesMikulas Patocka1-1/+1
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 <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-05-29dm thin metadata: remove in-core 'read_only' flagMike Snitzer1-0/+1
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 <snitzer@redhat.com>
2014-03-27dm transaction manager: fix corruption due to non-atomic transaction commitJoe Thornber1-2/+1
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 <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
2013-12-10dm thin: allow pool in read-only mode to transition to read-write modeJoe Thornber1-3/+4
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 <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
2013-08-23dm btree: prefetch child nodes when walking tree for a dm_btree_delJoe Thornber1-0/+5
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 <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-07-27dm persistent data: introduce dm_bm_set_read_onlyJoe Thornber1-0/+13
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 <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-07-27dm persistent data: stop using dm_bm_unlock_move when shadowing blocks in tmJoe Thornber1-8/+0
Stop using dm_bm_unlock_move when shadowing blocks in the transaction manager as an optimisation and remove the function as it is then no longer used. Some code, such as the space maps, keeps using on-disk data structures from the previous transaction. It can do this because blocks won't be reallocated until the subsequent transaction. Using dm_bm_unlock_move to copy blocks sounds like a win, but it forces a synchronous read should the old block be accessed. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-10-31dm: add persistent data libraryJoe Thornber1-0/+123
The persistent-data library offers a re-usable framework for the storage and management of on-disk metadata in device-mapper targets. It's used by the thin-provisioning target in the next patch and in an upcoming hierarchical storage target. For further information, please read Documentation/device-mapper/persistent-data.txt Signed-off-by: Joe Thornber <thornber@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>