kernel/drivers/md/md.h, branch linux-2.6.37.y

md: Fix - again - partition detection when array becomes active

2011-03-07T23:05:12Z

commit f0b4f7e2f29af678bd9af43422c537dcb6008603 upstream. Revert b821eaa572fd737faaf6928ba046e571526c36c6 and f3b99be19ded511a1bf05a148276239d9f13eefa When I wrote the first of these I had a wrong idea about the lifetime of 'struct block_device'. It can disappear at any time that the block device is not open if it falls out of the inode cache. So relying on the 'size' recorded with it to detect when the device size has changed and so we need to revalidate, is wrong. Rather, we really do need the 'changed' attribute stored directly in the mddev and set/tested as appropriate. Without this patch, a sequence of: mknod / open / close / unlink (which can cause a block_device to be created and then destroyed) will result in a rescan of the partition table and consequence removal and addition of partitions. Several of these in a row can get udev racing to create and unlink and other code can get confused. With the patch, the rescan is only performed when needed and so there are no races. This is suitable for any stable kernel from 2.6.35. Reported-by: "Wojcik, Krzysztof" Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

md: Ensure no IO request to get md device before it is properly initialised.

2011-02-17T23:14:54Z

commit 0ca69886a8273ac1350143d562280bfcbe4760dc upstream. When an md device is in the process of coming on line it is possible for an IO request (typically a partition table probe) to get through before the array is fully initialised, which can cause unexpected behaviour (e.g. a crash). So explicitly record when the array is ready for IO and don't allow IO through until then. There is no possibility for a similar problem when the array is going off-line as there must only be one 'open' at that time, and it is busy off-lining the array and so cannot send IO requests. So no memory barrier is needed in md_stop() This has been a bug since commit 409c57f3801 in 2.6.30 which introduced md_make_request. Before then, each personality would register its own make_request_fn when it was ready. This is suitable for any stable kernel from 2.6.30.y onwards. Signed-off-by: NeilBrown Reported-by: "Hawrylewicz Czarnowski, Przemyslaw" Signed-off-by: Greg Kroah-Hartman

md: use separate bio pool for each md device.

2010-10-28T06:36:15Z

bio_clone and bio_alloc allocate from a common bio pool. If an md device is stacked with other devices that use this pool, or under something like swap which uses the pool, then the multiple calls on the pool can cause deadlocks. So allocate a local bio pool for each md array and use that rather than the common pool. This pool is used both for regular IO and metadata updates. Signed-off-by: NeilBrown

md: change type of first arg to sync_page_io.

2010-10-28T06:36:11Z

Currently sync_page_io takes a 'bdev'. Every caller passes 'rdev->bdev'. We will soon want another field out of the rdev in sync_page_io, So just pass the rdev instead of the bdev out of it. Signed-off-by: NeilBrown

Merge branch 'v2.6.36-rc8' into for-2.6.37/barrier

2010-10-19T07:13:04Z

Conflicts: block/blk-core.c drivers/block/loop.c mm/swapfile.c Signed-off-by: Jens Axboe

md: implment REQ_FLUSH/FUA support

2010-09-10T10:35:38Z

This patch converts md to support REQ_FLUSH/FUA instead of now deprecated REQ_HARDBARRIER. In the core part (md.c), the following changes are notable. * Unlike REQ_HARDBARRIER, REQ_FLUSH/FUA don't interfere with processing of other requests and thus there is no reason to mark the queue congested while FLUSH/FUA is in progress. * REQ_FLUSH/FUA failures are final and its users don't need retry logic. Retry logic is removed. * Preflush needs to be issued to all member devices but FUA writes can be handled the same way as other writes - their processing can be deferred to request_queue of member devices. md_barrier_request() is renamed to md_flush_request() and simplified accordingly. For linear, raid0 and multipath, the core changes are enough. raid1, 5 and 10 need the following conversions. * raid1: Handling of FLUSH/FUA bio's can simply be deferred to request_queues of member devices. Barrier related logic removed. * raid5: Queue draining logic dropped. FUA bit is propagated through biodrain and stripe resconstruction such that all the updated parts of the stripe are written out with FUA writes if any of the dirtying writes was FUA. preread_active_stripes handling in make_request() is updated as suggested by Neil Brown. * raid10: FUA bit needs to be propagated to write clones. linear, raid0, 1, 5 and 10 tested. Signed-off-by: Tejun Heo Reviewed-by: Neil Brown Signed-off-by: Jens Axboe

md: resolve confusion of MD_CHANGE_CLEAN

2010-08-30T08:06:21Z

MD_CHANGE_CLEAN is used for two different purposes and this leads to confusion. One of the purposes is largely mirrored by MD_CHANGE_PENDING which is not used for anything else, so have MD_CHANGE_PENDING take over that purpose fully. The two purposes are: 1/ tell md_update_sb that an update is needed and that it is just a clean/dirty transition. 2/ tell user-space that an transition from clean to dirty is pending (something wants to write), and tell te kernel (by clearin the flag) that the transition is OK. The first purpose remains wit MD_CHANGE_CLEAN, the second is moved fully to MD_CHANGE_PENDING. This means that various places which conditionally set or cleared MD_CHANGE_CLEAN no longer need to be conditional. Signed-off-by: NeilBrown

Merge branch 'for-linus' of git://neil.brown.name/md

2010-08-10T22:38:19Z

* 'for-linus' of git://neil.brown.name/md: (24 commits) md: clean up do_md_stop md: fix another deadlock with removing sysfs attributes. md: move revalidate_disk() back outside open_mutex md/raid10: fix deadlock with unaligned read during resync md/bitmap: separate out loading a bitmap from initialising the structures. md/bitmap: prepare for storing write-intent-bitmap via dm-dirty-log. md/bitmap: optimise scanning of empty bitmaps. md/bitmap: clean up plugging calls. md/bitmap: reduce dependence on sysfs. md/bitmap: white space clean up and similar. md/raid5: export raid5 unplugging interface. md/plug: optionally use plugger to unplug an array during resync/recovery. md/raid5: add simple plugging infrastructure. md/raid5: export is_congested test raid5: Don't set read-ahead when there is no queue md: add support for raising dm events. md: export various start/stop interfaces md: split out md_rdev_init md: be more careful setting MD_CHANGE_CLEAN md/raid5: ensure we create a unique name for kmem_cache when mddev has no gendisk ...

md: fix another deadlock with removing sysfs attributes.

2010-08-08T11:21:27Z

Move the deletion of sysfs attributes from reconfig_mutex to open_mutex didn't really help as a process can try to take open_mutex while holding reconfig_mutex, so the same deadlock can happen, just requiring one more process to be involved in the chain. I looks like I cannot easily use locking to wait for the sysfs deletion to complete, so don't. The only things that we cannot do while the deletions are still pending is other things which can change the sysfs namespace: run, takeover, stop. Each of these can fail with -EBUSY. So set a flag while doing a sysfs deletion, and fail run, takeover, stop if that flag is set. This is suitable for 2.6.35.x Cc: stable@kernel.org Signed-off-by: NeilBrown

block: unify flags for struct bio and struct request

2010-08-07T16:20:39Z

Remove the current bio flags and reuse the request flags for the bio, too. This allows to more easily trace the type of I/O from the filesystem down to the block driver. There were two flags in the bio that were missing in the requests: BIO_RW_UNPLUG and BIO_RW_AHEAD. Also I've renamed two request flags that had a superflous RW in them. Note that the flags are in bio.h despite having the REQ_ name - as blkdev.h includes bio.h that is the only way to go for now. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe