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* dm kcopyd: return client directly and not through a pointerMikulas Patocka2011-05-293-9/+11
| | | | | | | | Return client directly from dm_kcopyd_client_create, not through a parameter, making it consistent with dm_io_client_create. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: reserve fewer pagesMikulas Patocka2011-05-293-11/+5
| | | | | | | | | | | Reserve just the minimum of pages needed to process one job. Because we allocate pages from page allocator, we don't need to reserve a large number of pages. The maximum job size is SUB_JOB_SIZE and we calculate the number of reserved pages based on this. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm io: use fixed initial mempool sizeMikulas Patocka2011-05-295-39/+9
| | | | | | | | | | | | | | | | | Replace the arbitrary calculation of an initial io struct mempool size with a constant. The code calculated the number of reserved structures based on the request size and used a "magic" multiplication constant of 4. This patch changes it to reserve a fixed number - itself still chosen quite arbitrarily. Further testing might show if there is a better number to choose. Note that if there is no memory pressure, we can still allocate an arbitrary number of "struct io" structures. One structure is enough to process the whole request. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: alloc pages from the main page allocatorMikulas Patocka2011-05-291-31/+60
| | | | | | | | | | This patch changes dm-kcopyd so that it allocates pages from the main page allocator with __GFP_NOWARN | __GFP_NORETRY flags (so that it can fail in case of memory pressure). If the allocation fails, dm-kcopyd allocates pages from its own reserve. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: add gfp parm to alloc_plMikulas Patocka2011-05-291-4/+4
| | | | | | | | Introduce a parameter for gfp flags to alloc_pl() for use in following patches. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: remove superfluous page allocation spinlockMikulas Patocka2011-05-291-10/+1
| | | | | | | | | | | | | | | | | | | | | | Remove the spinlock protecting the pages allocation. The spinlock is only taken on initialization or from single-threaded workqueue. Therefore, the spinlock is useless. The spinlock is taken in kcopyd_get_pages and kcopyd_put_pages. kcopyd_get_pages is only called from run_pages_job, which is only called from process_jobs called from do_work. kcopyd_put_pages is called from client_alloc_pages (which is initialization function) or from run_complete_job. run_complete_job is only called from process_jobs called from do_work. Another spinlock, kc->job_lock is taken each time someone pushes or pops some work for the worker thread. Once we take kc->job_lock, we guarantee that any written memory is visible to the other CPUs. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: preallocate sub jobs to avoid deadlockMikulas Patocka2011-05-291-20/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | There's a possible theoretical deadlock in dm-kcopyd because multiple allocations from the same mempool are required to finish a request. Avoid this by preallocating sub jobs. There is a mempool of 512 entries. Each request requires up to 9 entries from the mempool. If we have at least 57 concurrent requests running, the mempool may overflow and mempool allocations may start blocking until another entry is freed to the mempool. Because the same thread is used to free entries to the mempool and allocate entries from the mempool, this may result in a deadlock. This patch changes it so that one mempool entry contains all 9 "struct kcopyd_job" required to fulfill the whole request. The allocation is done only once in dm_kcopyd_copy and no further mempool allocations are done during request processing. If dm_kcopyd_copy is not run in the completion thread, this implementation is deadlock-free. MIN_JOBS needs reducing accordingly and we've chosen to reduce it further to 8. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: avoid pointless job splittingMikulas Patocka2011-05-291-1/+1
| | | | | | | | | | | Don't split SUB_JOB_SIZE jobs If the job size equals SUB_JOB_SIZE, there is no point in splitting it. Splitting it just unnecessarily wastes time, because the split job size is SUB_JOB_SIZE too. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm mpath: do not fail paths after integrity errorsMartin K. Petersen2011-05-291-1/+1
| | | | | | | | | | | Integrity errors need to be passed to the owner of the integrity metadata for processing. Consequently EILSEQ should be passed up the stack. Cc: stable@kernel.org Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm table: reject devices without request fnsMilan Broz2011-05-291-0/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds a check that a block device has a request function defined before it is used. Otherwise, misconfiguration can cause an oops. Because we are allowing devices with zero size e.g. an offline multipath device as in commit 2cd54d9bedb79a97f014e86c0da393416b264eb3 ("dm: allow offline devices") there needs to be an additional check to ensure devices are initialised. Some block devices, like a loop device without a backing file, exist but have no request function. Reproducer is trivial: dm-mirror on unbound loop device (no backing file on loop devices) dmsetup create x --table "0 8 mirror core 2 8 sync 2 /dev/loop0 0 /dev/loop1 0" and mirror resync will immediatelly cause OOps. BUG: unable to handle kernel NULL pointer dereference at (null) ? generic_make_request+0x2bd/0x590 ? kmem_cache_alloc+0xad/0x190 submit_bio+0x53/0xe0 ? bio_add_page+0x3b/0x50 dispatch_io+0x1ca/0x210 [dm_mod] ? read_callback+0x0/0xd0 [dm_mirror] dm_io+0xbb/0x290 [dm_mod] do_mirror+0x1e0/0x748 [dm_mirror] Signed-off-by: Milan Broz <mbroz@redhat.com> Reported-by: Zdenek Kabelac <zkabelac@redhat.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@kernel.org Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm table: allow targets to support discards internallyMike Snitzer2011-05-291-1/+5
| | | | | | | | Permit a target to support discards regardless of whether or not all its underlying devices do. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2011-05-231-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (39 commits) b43: fix comment typo reqest -> request Haavard Skinnemoen has left Atmel cris: typo in mach-fs Makefile Kconfig: fix copy/paste-ism for dell-wmi-aio driver doc: timers-howto: fix a typo ("unsgined") perf: Only include annotate.h once in tools/perf/util/ui/browsers/annotate.c md, raid5: Fix spelling error in comment ('Ofcourse' --> 'Of course'). treewide: fix a few typos in comments regulator: change debug statement be consistent with the style of the rest Revert "arm: mach-u300/gpio: Fix mem_region resource size miscalculations" audit: acquire creds selectively to reduce atomic op overhead rtlwifi: don't touch with treewide double semicolon removal treewide: cleanup continuations and remove logging message whitespace ath9k_hw: don't touch with treewide double semicolon removal include/linux/leds-regulator.h: fix syntax in example code tty: fix typo in descripton of tty_termios_encode_baud_rate xtensa: remove obsolete BKL kernel option from defconfig m68k: fix comment typo 'occcured' arch:Kconfig.locks Remove unused config option. treewide: remove extra semicolons ...
| * md, raid5: Fix spelling error in comment ('Ofcourse' --> 'Of course').Jesper Juhl2011-05-101-1/+1
| | | | | | | | | | | | | | | | There's a small typo in a comment in drivers/md/raid5.c - 'Of course' is misspelled as 'Ofcourse'. This patch fixes the spelling error. Signed-off-by: Jesper Juhl <jj@chaosbits.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* | md: allow resync_start to be set while an array is active.NeilBrown2011-05-113-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The sysfs attribute 'resync_start' (known internally as recovery_cp), records where a resync is up to. A value of 0 means the array is not known to be in-sync at all. A value of MaxSector means the array is believed to be fully in-sync. When the size of member devices of an array (RAID1,RAID4/5/6) is increased, the array can be increased to match. This process sets resync_start to the old end-of-device offset so that the new part of the array gets resynced. However with RAID1 (and RAID6) a resync is not technically necessary and may be undesirable. So it would be good if the implied resync after the array is resized could be avoided. So: change 'resync_start' so the value can be changed while the array is active, and as a precaution only allow it to be changed while resync/recovery is 'frozen'. Changing it once resync has started is not going to be useful anyway. This allows the array to be resized without a resync by: write 'frozen' to 'sync_action' write new size to 'component_size' (this will set resync_start) write 'none' to 'resync_start' write 'idle' to 'sync_action'. Also slightly improve some tests on recovery_cp when resizing raid1/raid5. Now that an arbitrary value could be set we should be more careful in our tests. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid10: reformat some loops with less indenting.NeilBrown2011-05-111-108/+120
| | | | | | | | | | | | | | | | | | | | When a loop ends with an 'if' with a large body, it is neater to make the if 'continue' on the inverse condition, and then the body is indented less. Apply this pattern 3 times, and wrap some other long lines. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid10: remove unused variable.NeilBrown2011-05-111-3/+0
| | | | | | | | | | | | This variable 'disk' is never used - how odd. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid10: make more use of 'slot' in raid10d.NeilBrown2011-05-111-4/+5
| | | | | | | | | | | | | | Now that we have a 'slot' variable, make better use of it to simplify some code a little. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid10: some tidying up in fix_read_errorNeilBrown2011-05-111-40/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently the rdev on which a read error happened could be removed before we perform the fix_error handling. This requires extra tests for NULL. So delay the rdev_dec_pending call until after the call to fix_read_error so that we can be sure that the rdev still exists. This allows an 'if' clause to be removed so the body gets re-indented back one level. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid1: improve handling of pages allocated for write-behind.NeilBrown2011-05-112-30/+29
| | | | | | | | | | | | | | | | | | | | | | The current handling and freeing of these pages is a bit fragile. We only keep the list of allocated pages in each bio, so we need to still have a valid bio when freeing the pages, which is a bit clumsy. So simply store the allocated page list in the r1_bio so it can easily be found and freed when we are finished with the r1_bio. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid1: try fix_sync_read_error before process_checks.NeilBrown2011-05-111-14/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we get a read error during resync/recovery we current repeat with single-page reads to find out just where the error is, and possibly read each page from a different device. With check/repair we don't currently do that, we just fail. However it is possible that while all devices fail on the large 64K read, we might be able to satisfy each 4K from one device or another. So call fix_sync_read_error before process_checks to maximise the chance of finding good data and writing it out to the devices with read errors. For this to work, we need to set the 'uptodate' flags properly after fix_sync_read_error has succeeded. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid1: tidy up new functions: process_checks and fix_sync_read_error.NeilBrown2011-05-111-89/+95
| | | | | | | | | | | | | | | | | | | | | | | | These changes are mostly cosmetic: 1/ change mddev->raid_disks to conf->raid_disks because the later is technically safer, though in current practice it doesn't matter in this particular context. 2/ Rearrange two for / if loops to have an early 'continue' so the body of the 'if' doesn't need to be indented so much. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid1: split out two sub-functions from sync_request_writeNeilBrown2011-05-111-173/+192
| | | | | | | | | | | | | | | | sync_request_write is too big and too deep. So split out two self-contains bits of functionality into separate function. Signed-off-by: NeilBrown <neilb@suse.de>
* | md: make error_handler functions more uniform and correct.NeilBrown2011-05-112-38/+40
| | | | | | | | | | | | | | | | | | | | | | | | - there is no need to test_bit Faulty, as that was already done in md_error which is the only caller of these functions. - MD_CHANGE_DEVS should be set *after* faulty is set to ensure metadata is updated correctly. - spinlock should be held while updating ->degraded. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/multipath: discard ->working_disks in favour of ->degradedNeilBrown2011-05-112-12/+11
| | | | | | | | | | | | | | | | conf->working_disks duplicates information already available in mddev->degraded. So remove working_disks. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/raid1: clean up read_balance.NeilBrown2011-05-111-49/+34
| | | | | | | | | | | | | | | | | | | | read_balance has two loops which both look for a 'best' device based on slightly different criteria. This is clumsy and makes is hard to add extra criteria. So replace it all with a single loop that combines everything. Signed-off-by: NeilBrown <neilb@suse.de>
* | md: simplify raid10 read_balanceNeilBrown2011-05-111-66/+44
| | | | | | | | | | | | | | | | | | raid10 read balance has two different loop for looking through possible devices to chose the best. Collapse those into one loop and generally make the code more readable. Signed-off-by: NeilBrown <neilb@suse.de>
* | md/bitmap: fix saving of events_cleared and other state.NeilBrown2011-05-111-4/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a bitmap is found to be 'stale' the events_cleared value is set to match 'events'. However if the array is degraded this does not get stored on disk. This can subsequently lead to incorrect behaviour. So change bitmap_update_sb to always update events_cleared in the superblock from the known events_cleared. For neatness also set ->state from ->flags. This requires updating ->state whenever we update ->flags, which makes sense anyway. This is suitable for any active -stable release. cc: stable@kernel.org Signed-off-by: NeilBrown <neilb@suse.de>
* | md: reject a re-add request that cannot be honoured.NeilBrown2011-05-111-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The 'add_new_disk' ioctl can be used to add a device either as a spare, or as an active disk that just needs to be resynced based on write-intent-bitmap information (re-add) Currently if a re-add is requested but fails we add as a spare instead. This makes it impossible for user-space to check for failure. So change to require that a re-add attempt will either succeed or completely fail. User-space can then decide what to do next. Signed-off-by: NeilBrown <neilb@suse.de>
* | md: Fix race when creating a new md device.NeilBrown2011-05-111-3/+8
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a race when creating an md device by opening /dev/mdXX. If two processes do this at much the same time they will follow the call path __blkdev_get -> get_gendisk -> kobj_lookup The first will call -> md_probe -> md_alloc -> add_disk -> blk_register_region and the race happens when the second gets to kobj_lookup after add_disk has called blk_register_region but before it returns to md_alloc. In the case the second will not call md_probe (as the probe is already done) but will get a handle on the gendisk, return to __blkdev_get which will then call md_open (via the ->open) pointer. As mddev->gendisk hasn't been set yet, md_open will think something is wrong an return with ERESTARTSYS. This can loop endlessly while the first thread makes no progress through add_disk. Nothing is blocking it, but due to scheduler behaviour it doesn't get a turn. So this is essentially a live-lock. We fix this by simply moving the assignment to mddev->gendisk before the call the add_disk() so md_open doesn't get confused. Also move blk_queue_flush earlier because add_disk should be as late as possible. To make sure that md_open doesn't complete until md_alloc has done all that is needed, we take mddev->open_mutex during the last part of md_alloc. md_open will wait for this. This can cause a lock-up on boot so Cc:ing for stable. For 2.6.36 and earlier a different patch will be needed as the 'blk_queue_flush' call isn't there. Signed-off-by: NeilBrown <neilb@suse.de> Reported-by: Thomas Jarosch <thomas.jarosch@intra2net.com> Tested-by: Thomas Jarosch <thomas.jarosch@intra2net.com> Cc: stable@kernel.org
* raid5: fix build error, sector_t usageRandy Dunlap2011-04-211-1/+1
| | | | | | | | | | Change <sectors> from unsigned long long to sector_t. This matches its source field. ERROR: "__udivdi3" [drivers/md/raid456.ko] undefined! Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* md: Cleanup after raid45->raid0 takeoverKrzysztof Wojcik2011-04-201-0/+1
| | | | | | | | | | | | | | Problem: After raid4->raid0 takeover operation, another takeover operation (e.g raid0->raid10) results "kernel oops". Root cause: Variables 'degraded' in mddev structure is not cleared on raid45->raid0 takeover. This patch reset this variable. Signed-off-by: Krzysztof Wojcik <krzysztof.wojcik@intel.com> Signed-off-by: NeilBrown <neilb@suse.de>
* md: Fix dev_sectors on takeover from raid0 to raid4/5NeilBrown2011-04-201-0/+4
| | | | | | | | | | | A raid0 array doesn't set 'dev_sectors' as each device might contribute a different number of sectors. So when converting to a RAID4 or RAID5 we need to set dev_sectors as they need the number. We have already verified that in fact all devices do contribute the same number of sectors, so use that number. Signed-off-by: NeilBrown <neilb@suse.de>
* md/raid5: remove setting of ->queue_lockNeilBrown2011-04-201-1/+0
| | | | | | | | | | | We previously needed to set ->queue_lock to match the raid5 device_lock so we could safely use queue_flag_* operations (e.g. for plugging). which test the ->queue_lock is in fact locked. However that need has completely gone away and is unlikely to come back to remove this now-pointless setting. Signed-off-by: NeilBrown <neilb@suse.de>
* md: fix up raid1/raid10 unplugging.NeilBrown2011-04-182-28/+20
| | | | | | | | | We just need to make sure that an unplug event wakes up the md thread, which is exactly what mddev_check_plugged does. Also remove some plug-related code that is no longer needed. Signed-off-by: NeilBrown <neilb@suse.de>
* md: incorporate new plugging into raid5.NeilBrown2011-04-181-7/+16
| | | | | | | | | | | | | | | | In raid5 plugging is used for 2 things: 1/ collecting writes that require a bitmap update 2/ collecting writes in the hope that we can create full stripes - or at least more-full. We now release these different sets of stripes when plug_cnt is zero. Also in make_request, we call mddev_check_plug to hopefully increase plug_cnt, and wake up the thread at the end if plugging wasn't achieved for some reason. Signed-off-by: NeilBrown <neilb@suse.de>
* md: provide generic support for handling unplug callbacks.NeilBrown2011-04-182-0/+60
| | | | | | | | | | | | | When an md device adds a request to a queue, it can call mddev_check_plugged. If this succeeds then we know that the md thread will be woken up shortly, and ->plug_cnt will be non-zero until then, so some processing can be delayed. If it fails, then no unplug callback is expected and the make_request function needs to do whatever is required to make the request happen. Signed-off-by: NeilBrown <neilb@suse.de>
* md - remove old plugging code.NeilBrown2011-04-184-104/+8
| | | | | | | | | | | | | md has some plugging infrastructure for RAID5 to use because the normal plugging infrastructure required a 'request_queue', and when called from dm, RAID5 doesn't have one of those available. This relied on the ->unplug_fn callback which doesn't exist any more. So remove all of that code, both in md and raid5. Subsequent patches with restore the plugging functionality. Signed-off-by: NeilBrown <neilb@suse.de>
* md/dm - remove remains of plug_fn callback.NeilBrown2011-04-181-8/+0
| | | | | | | Now that unplugging is done differently, the unplug_fn callback is never called, so it can be completely discarded. Signed-off-by: NeilBrown <neilb@suse.de>
* md: use new plugging interface for RAID IO.NeilBrown2011-04-183-1/+10
| | | | | | | | md/raid submits a lot of IO from the various raid threads. So adding start/finish plug calls to those so that some plugging happens. Signed-off-by: NeilBrown <neilb@suse.de>
* Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6Linus Torvalds2011-04-077-10/+10
|\ | | | | | | | | * 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6: Fix common misspellings
| * Fix common misspellingsLucas De Marchi2011-03-317-10/+10
| | | | | | | | | | | | Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
* | dm: improve block integrity supportMike Snitzer2011-04-051-34/+80
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current block integrity (DIF/DIX) support in DM is verifying that all devices' integrity profiles match during DM device resume (which is past the point of no return). To some degree that is unavoidable (stacked DM devices force this late checking). But for most DM devices (which aren't stacking on other DM devices) the ideal time to verify all integrity profiles match is during table load. Introduce the notion of an "initialized" integrity profile: a profile that was blk_integrity_register()'d with a non-NULL 'blk_integrity' template. Add blk_integrity_is_initialized() to allow checking if a profile was initialized. Update DM integrity support to: - check all devices with _initialized_ integrity profiles match during table load; uninitialized profiles (e.g. for underlying DM device(s) of a stacked DM device) are ignored. - disallow a table load that would result in an integrity profile that conflicts with a DM device's existing (in-use) integrity profile - avoid clearing an existing integrity profile - validate all integrity profiles match during resume; but if they don't all we can do is report the mismatch (during resume we're past the point of no return) Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* md: Fix integrity registration error when no devices are capableMartin K. Petersen2011-03-281-6/+2
| | | | | | | | | | | | We incorrectly returned -EINVAL when none of the devices in the array had an integrity profile. This in turn prevented mdadm from starting the metadevice. Fix this so we only return errors on mismatched profiles and memory allocation failures. Reported-by: Giacomo Catenazzi <cate@cateee.net> Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dmLinus Torvalds2011-03-259-28/+300
|\ | | | | | | | | | | | | | | | | | | | | | | * git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: dm stripe: implement merge method dm mpath: allow table load with no priority groups dm mpath: fail message ioctl if specified path is not valid dm ioctl: add flag to wipe buffers for secure data dm ioctl: prepare for crypt key wiping dm crypt: wipe keys string immediately after key is set dm: add flakey target dm: fix opening log and cow devices for read only tables
| * dm stripe: implement merge methodMustafa Mesanovic2011-03-241-1/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implement a merge function in the striped target. When the striped target's underlying devices provide a merge_bvec_fn (like all DM devices do via dm_merge_bvec) it is important to call down to them when building a biovec that doesn't span a stripe boundary. Without the merge method, a striped DM device stacked on DM devices causes bios with a single page to be submitted which results in unnecessary overhead that hurts performance. This change really helps filesystems (e.g. XFS and now ext4) which take care to assemble larger bios. By implementing stripe_merge(), DM and the stripe target no longer undermine the filesystem's work by only allowing a single page per bio. Buffered IO sees the biggest improvement (particularly uncached reads, buffered writes to a lesser degree). This is especially so for more capable "enterprise" storage LUNs. The performance improvement has been measured to be ~12-35% -- when a reasonable chunk_size is used (e.g. 64K) in conjunction with a stripe count that is a power of 2. In contrast, the performance penalty is ~5-7% for the pathological worst case stripe configuration (small chunk_size with a stripe count that is not a power of 2). The reason for this is that stripe_map_sector() is now called once for every call to dm_merge_bvec(). stripe_map_sector() will use slower division if stripe count isn't a power of 2. Signed-off-by: Mustafa Mesanovic <mume@linux.vnet.ibm.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| * dm mpath: allow table load with no priority groupsMike Snitzer2011-03-241-3/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adjusts the multipath target to allow a table with both 0 priority groups and 0 for the initial priority group number. If any mpath device is held open when all paths in the last priority group have failed, userspace multipathd will attempt to reload the associated DM table to reflect the fact that the device no longer has any priority groups. But the reload attempt always failed because the multipath target did not allow 0 priority groups. All multipath target messages related to priority group (enable_group, disable_group, switch_group) will handle a priority group of 0 (will cause error). When reloading a multipath table with 0 priority groups, userspace multipathd must be updated to specify an initial priority group number of 0 (rather than 1). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: Babu Moger <babu.moger@lsi.com> Acked-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| * dm mpath: fail message ioctl if specified path is not validMike Snitzer2011-03-241-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fail the reinstate_path and fail_path message ioctl if the specified path is not valid. The message ioctl would succeed for the 'reinistate_path' and 'fail_path' messages even if action was not taken because the specified device was not a valid path of the multipath device. Before, when /dev/vdb is not a path of mpathb: $ dmsetup message mpathb 0 reinstate_path /dev/vdb $ echo $? 0 After: $ dmsetup message mpathb 0 reinstate_path /dev/vdb device-mapper: message ioctl failed: Invalid argument Command failed $ echo $? 1 Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| * dm ioctl: add flag to wipe buffers for secure dataMilan Broz2011-03-241-2/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add DM_SECURE_DATA_FLAG which userspace can use to ensure that all buffers allocated for dm-ioctl are wiped immediately after use. The user buffer is wiped as well (we do not want to keep and return sensitive data back to userspace if the flag is set). Wiping is useful for cryptsetup to ensure that the key is present in memory only in defined places and only for the time needed. (For crypt, key can be present in table during load or table status, wait and message commands). Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| * dm ioctl: prepare for crypt key wipingMilan Broz2011-03-241-14/+11
| | | | | | | | | | | | | | | | | | Prepare code for implementing buffer wipe flag. No functional change in this patch. Signed-off-by: Milan Broz <mbroz@redhat.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| * dm crypt: wipe keys string immediately after key is setMilan Broz2011-03-241-5/+14
| | | | | | | | | | | | | | | | | | Always wipe the original copy of the key after processing it in crypt_set_key(). Signed-off-by: Milan Broz <mbroz@redhat.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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