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path: root/drivers/md/persistent-data/dm-transaction-manager.h
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* dm persistent data: eliminate unnecessary return valuesMikulas Patocka2015-10-311-1/+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>
* dm transaction manager: add support for prefetching blocks of metadataJoe Thornber2014-11-101-0/+7
| | | | | | | | | | Introduce the dm_tm_issue_prefetches interface. If you're using a non-blocking clone the tm will build up a list of requested blocks that weren't in core. dm_tm_issue_prefetches will request those blocks to be prefetched. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
* dm transaction manager: fix corruption due to non-atomic transaction commitJoe Thornber2014-03-271-9/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* dm persistent data: tidy transaction manager creation fnsJoe Thornber2012-07-271-5/+6
| | | | | | | | | | | | | Tidy the transaction manager creation functions. They no longer lock the superblock. Superblock locking is pulled out to the caller. Also export dm_bm_write_lock_zero. 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>
* dm: add persistent data libraryJoe Thornber2011-10-311-0/+130
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>
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