linux/drivers/md/dm-bio-list.h, branch v2.6.31-rc2

block: move bio list helpers into bio.h

2009-04-15T06:28:09Z

It's used by DM and MD and generally useful, so move the bio list helpers into bio.h. Signed-off-by: Christoph Hellwig Acked-by: Alasdair G Kergon Signed-off-by: Jens Axboe

dm: bio list add bio_list_add_head

2009-04-02T18:55:36Z

Introduce a function that adds a bio to the head of the list for use by the patch that will support barriers. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm: bio_list macro renaming

2007-10-20T01:01:11Z

Remove BIO_LIST and DEFINE_BIO_LIST macros that gain us nothing since contents are initialised to NULL. Cc: Jan Engelhardt Signed-off-by: Alasdair G Kergon

Fix kernel buuild with (CONFIG_COMPAT && ! CONFIG_BLOCK)

2007-09-14T20:56:47Z

Commit 02a5e0acb3cb85d80d0fe834e366d38a92bbaa22 ("BLOCK: Hide the contents of linux/bio.h if CONFIG_BLOCK=n") broke the kernel build for the CONFIG_COMPAT && !CONFIG_BLOCK case: CC fs/compat_ioctl.o In file included from include/linux/raid/md_k.h:19, from include/linux/raid/md.h:54, from fs/compat_ioctl.c:25: include/linux/raid/../../../drivers/md/dm-bio-list.h: In bio_list_: include/linux/raid/../../../drivers/md/dm-bio-list.h:40: error: dereferencing pointer to incomplete type include/linux/raid/../../../drivers/md/dm-bio-list.h: In bio_list_: include/linux/raid/../../../drivers/md/dm-bio-list.h:48: error: dereferencing pointer to incomplete type include/linux/raid/../../../drivers/md/dm-bio-list.h:51: error: dereferencing pointer to incomplete type include/linux/raid/../../../drivers/md/dm-bio-list.h: In bio_list_: include/linux/raid/../../../drivers/md/dm-bio-list.h:64: error: dereferencing pointer to incomplete type include/linux/raid/../../../drivers/md/dm-bio-list.h: In bio_list_merge_: include/linux/raid/../../../drivers/md/dm-bio-list.h:78: error: dereferencing pointer to incomplete type include/linux/raid/../../../drivers/md/dm-bio-list.h: In bio_list_: include/linux/raid/../../../drivers/md/dm-bio-list.h:90: error: dereferencing pointer to incomplete type include/linux/raid/../../../drivers/md/dm-bio-list.h:94: error: dereferencing pointer to incomplete type make[1]: *** [fs/compat_ioctl.o] Error 1 make: *** [fs] Error 2 Signed-off-by: Andreas Herrmann Acked-By: David Howells Signed-off-by: Linus Torvalds

dm: bio_list prefetch removal

2007-07-12T22:01:08Z

Remove dubious prefetch from bio_list_for_each() macro. Cc: Jens Axboe Signed-off-by: Alasdair G Kergon Signed-off-by: Linus Torvalds

dm: bio list helpers

2007-05-09T19:30:47Z

More bio_list helper functions for new targets (including dm-delay and dm-loop) to manipulate lists of bios. Signed-off-by: Heinz Mauelshagen Signed-off-by: Bryn Reeves Signed-off-by: Milan Broz Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] dm: suspend: add noflush pushback

2006-12-08T16:29:09Z

In device-mapper I/O is sometimes queued within targets for later processing. For example the multipath target can be configured to store I/O when no paths are available instead of returning it -EIO. This patch allows the device-mapper core to instruct a target to transfer the contents of any such in-target queue back into the core. This frees up the resources used by the target so the core can replace that target with an alternative one and then resend the I/O to it. Without this patch the only way to change the target in such circumstances involves returning the I/O with an error back to the filesystem/application. In the multipath case, this patch will let us add new paths for existing I/O to try after all the existing paths have failed. DMF_NOFLUSH_SUSPENDING ---------------------- If the DM_NOFLUSH_FLAG ioctl option is specified at suspend time, the DMF_NOFLUSH_SUSPENDING flag is set in md->flags during dm_suspend(). It is always cleared before dm_suspend() returns. The flag must be visible while the target is flushing pending I/Os so it is set before presuspend where the flush starts and unset after the wait for md->pending where the flush ends. Target drivers can check this flag by calling dm_noflush_suspending(). DM_MAPIO_REQUEUE / DM_ENDIO_REQUEUE ----------------------------------- A target's map() function can now return DM_MAPIO_REQUEUE to request the device mapper core queue the bio. Similarly, a target's end_io() function can return DM_ENDIO_REQUEUE to request the same. This has been labelled 'pushback'. The __map_bio() and clone_endio() functions in the core treat these return values as errors and call dec_pending() to end the I/O. dec_pending ----------- dec_pending() saves the pushback request in struct dm_io->error. Once all the split clones have ended, dec_pending() will put the original bio on the md->pushback list. Note that this supercedes any I/O errors. It is possible for the suspend with DM_NOFLUSH_FLAG to be aborted while in progress (e.g. by user interrupt). dec_pending() checks for this and returns -EIO if it happened. pushdback list and pushback_lock -------------------------------- The bio is queued on md->pushback temporarily in dec_pending(), and after all pending I/Os return, md->pushback is merged into md->deferred in dm_suspend() for re-issuing at resume time. md->pushback_lock protects md->pushback. The lock should be held with irq disabled because dec_pending() can be called from interrupt context. Queueing bios to md->pushback in dec_pending() must be done atomically with the check for DMF_NOFLUSH_SUSPENDING flag. So md->pushback_lock is held when checking the flag. Otherwise dec_pending() may queue a bio to md->pushback after the interrupted dm_suspend() flushes md->pushback. Then the bio would be left in md->pushback. Flag setting in dm_suspend() can be done without md->pushback_lock because the flag is checked only after presuspend and the set value is already made visible via the target's presuspend function. The flag can be checked without md->pushback_lock (e.g. the first part of the dec_pending() or target drivers), because the flag is checked again with md->pushback_lock held when the bio is really queued to md->pushback as described above. So even if the flag is cleared after the lockless checkings, the bio isn't left in md->pushback but returned to applications with -EIO. Other notes on the current patch -------------------------------- - md->pushback is added to the struct mapped_device instead of using md->deferred directly because md->io_lock which protects md->deferred is rw_semaphore and can't be used in interrupt context like dec_pending(), and md->io_lock protects the DMF_BLOCK_IO flag of md->flags too. - Don't issue lock_fs() in dm_suspend() if the DM_NOFLUSH_FLAG ioctl option is specified, because I/Os generated by lock_fs() would be pushed back and never return if there were no valid devices. - If an error occurs in dm_suspend() after the DMF_NOFLUSH_SUSPENDING flag is set, md->pushback must be flushed because I/Os may be queued to the list already. (flush_and_out label in dm_suspend()) Test results ------------ I have tested using multipath target with the next patch. The following tests are for regression/compatibility: - I/Os succeed when valid paths exist; - I/Os fail when there are no valid paths and queue_if_no_path is not set; - I/Os are queued in the multipath target when there are no valid paths and queue_if_no_path is set; - The queued I/Os above fail when suspend is issued without the DM_NOFLUSH_FLAG ioctl option. I/Os spanning 2 multipath targets also fail. The following tests are for the normal code path of new pushback feature: - Queued I/Os in the multipath target are flushed from the target but don't return when suspend is issued with the DM_NOFLUSH_FLAG ioctl option; - The I/Os above are queued in the multipath target again when resume is issued without path recovery; - The I/Os above succeed when resume is issued after path recovery or table load; - Queued I/Os in the multipath target succeed when resume is issued with the DM_NOFLUSH_FLAG ioctl option after table load. I/Os spanning 2 multipath targets also succeed. The following tests are for the error paths of the new pushback feature: - When the bdget_disk() fails in dm_suspend(), the DMF_NOFLUSH_SUSPENDING flag is cleared and I/Os already queued to the pushback list are flushed properly. - When suspend with the DM_NOFLUSH_FLAG ioctl option is interrupted, o I/Os which had already been queued to the pushback list at the time don't return, and are re-issued at resume time; o I/Os which hadn't been returned at the time return with EIO. Signed-off-by: Kiyoshi Ueda Signed-off-by: Jun'ichi Nomura Signed-off-by: Alasdair G Kergon Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] device-mapper snapshot: bio_list fix

2005-11-22T17:14:31Z

bio_list_merge() should do nothing if the second list is empty - not oops. Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Linux-2.6.12-rc2

2005-04-16T22:20:36Z

Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!