linux/block/blk-barrier.c, branch v2.6.39-rc2

block: rename blk-barrier.c to blk-flush.c

2010-09-10T10:35:36Z

Without ordering requirements, barrier and ordering are minomers. Rename block/blk-barrier.c to block/blk-flush.c. Rename of symbols will follow. Signed-off-by: Tejun Heo Cc: Christoph Hellwig Signed-off-by: Jens Axboe

block: drop barrier ordering by queue draining

2010-09-10T10:35:36Z

Filesystems will take all the responsibilities for ordering requests around commit writes and will only indicate how the commit writes themselves should be handled by block layers. This patch drops barrier ordering by queue draining from block layer. Ordering by draining implementation was somewhat invasive to request handling. List of notable changes follow. * Each queue has 1 bit color which is flipped on each barrier issue. This is used to track whether a given request is issued before the current barrier or not. REQ_ORDERED_COLOR flag and coloring implementation in __elv_add_request() are removed. * Requests which shouldn't be processed yet for draining were stalled by returning -EAGAIN from blk_do_ordered() according to the test result between blk_ordered_req_seq() and blk_blk_ordered_cur_seq(). This logic is removed. * Draining completion logic in elv_completed_request() removed. * All barrier sequence requests were queued to request queue and then trckled to lower layer according to progress and thus maintaining request orders during requeue was necessary. This is replaced by queueing the next request in the barrier sequence only after the current one is complete from blk_ordered_complete_seq(), which removes the need for multiple proxy requests in struct request_queue and the request sorting logic in the ELEVATOR_INSERT_REQUEUE path of elv_insert(). * As barriers no longer have ordering constraints, there's no need to dump the whole elevator onto the dispatch queue on each barrier. Insert barriers at the front instead. * If other barrier requests come to the front of the dispatch queue while one is already in progress, they are stored in q->pending_barriers and restored to dispatch queue one-by-one after each barrier completion from blk_ordered_complete_seq(). Signed-off-by: Tejun Heo Cc: Christoph Hellwig Signed-off-by: Jens Axboe

block: misc cleanups in barrier code

2010-09-10T10:35:36Z

Make the following cleanups in preparation of barrier/flush update. * blk_do_ordered() declaration is moved from include/linux/blkdev.h to block/blk.h. * blk_do_ordered() now returns pointer to struct request, with %NULL meaning "try the next request" and ERR_PTR(-EAGAIN) "try again later". The third case will be dropped with further changes. * In the initialization of proxy barrier request, data direction is already set by init_request_from_bio(). Drop unnecessary explicit REQ_WRITE setting and move init_request_from_bio() above REQ_FUA flag setting. * add_request() is collapsed into __make_request(). These changes don't make any functional difference. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe

block: deprecate barrier and replace blk_queue_ordered() with blk_queue_flush()

2010-09-10T10:35:36Z

Barrier is deemed too heavy and will soon be replaced by FLUSH/FUA requests. Deprecate barrier. All REQ_HARDBARRIERs are failed with -EOPNOTSUPP and blk_queue_ordered() is replaced with simpler blk_queue_flush(). blk_queue_flush() takes combinations of REQ_FLUSH and FUA. If a device has write cache and can flush it, it should set REQ_FLUSH. If the device can handle FUA writes, it should also set REQ_FUA. All blk_queue_ordered() users are converted. * ORDERED_DRAIN is mapped to 0 which is the default value. * ORDERED_DRAIN_FLUSH is mapped to REQ_FLUSH. * ORDERED_DRAIN_FLUSH_FUA is mapped to REQ_FLUSH | REQ_FUA. Signed-off-by: Tejun Heo Acked-by: Boaz Harrosh Cc: Christoph Hellwig Cc: Nick Piggin Cc: Michael S. Tsirkin Cc: Jeremy Fitzhardinge Cc: Chris Wright Cc: FUJITA Tomonori Cc: Geert Uytterhoeven Cc: David S. Miller Cc: Alasdair G Kergon Cc: Pierre Ossman Cc: Stefan Weinhuber Signed-off-by: Jens Axboe

block: kill QUEUE_ORDERED_BY_TAG

2010-09-10T10:35:36Z

Nobody is making meaningful use of ORDERED_BY_TAG now and queue draining for barrier requests will be removed soon which will render the advantage of tag ordering moot. Kill ORDERED_BY_TAG. The following users are affected. * brd: converted to ORDERED_DRAIN. * virtio_blk: ORDERED_TAG path was already marked deprecated. Removed. * xen-blkfront: ORDERED_TAG case dropped. Signed-off-by: Tejun Heo Cc: Christoph Hellwig Cc: Nick Piggin Cc: Michael S. Tsirkin Cc: Jeremy Fitzhardinge Cc: Chris Wright Signed-off-by: Jens Axboe

block: set up rq->rq_disk properly for flush requests

2010-08-07T16:52:41Z

q->bar_rq.rq_disk is NULL. Use the rq_disk of the original request instead. Signed-off-by: FUJITA Tomonori Signed-off-by: Jens Axboe

block: set REQ_TYPE_FS on flush requests

2010-08-07T16:52:40Z

the block layer doesn't set rq->cmd_type on flush requests. By definition, it should be REQ_TYPE_FS (the lower layers build a command and interpret the result of it, that is, the block layer doesn't know the details). Signed-off-by: FUJITA Tomonori Signed-off-by: Jens Axboe

blkdev: check for valid request queue before issuing flush

2010-08-07T16:26:29Z

Issuing a blkdev_issue_flush() on an unconfigured loop device causes a panic as q->make_request_fn is not configured. This can occur when trying to mount the unconfigured loop device as an XFS filesystem. There are no guards that catch the bio before the request function is called because we don't add a payload to the bio. Instead, manually check this case as soon as we have a pointer to the queue to flush. Signed-off-by: Dave Chinner Signed-off-by: Jens Axboe

block: remove q->prepare_flush_fn completely

2010-08-07T16:24:15Z

This removes q->prepare_flush_fn completely (changes the blk_queue_ordered API). Signed-off-by: FUJITA Tomonori Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

block: permit PREFLUSH and POSTFLUSH without prepare_flush_fn

2010-08-07T16:23:56Z

This is preparation for removing q->prepare_flush_fn. Temporarily, blk_queue_ordered() permits QUEUE_ORDERED_DO_PREFLUSH and QUEUE_ORDERED_DO_POSTFLUSH without prepare_flush_fn. Signed-off-by: FUJITA Tomonori Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe