BMC/Intel-BMC/linux.git/block/blk-mq-tag.c, branch dev

blk-mq: Shared tag enhancements

2015-06-01T20:35:56+00:00

Storage controllers may expose multiple block devices that share hardware resources managed by blk-mq. This patch enhances the shared tags so a low-level driver can access the shared resources not tied to the unshared h/w contexts. This way the LLD can dynamically add and delete disks and request queues without having to track all the request_queue hctx's to iterate outstanding tags. Signed-off-by: Keith Busch Signed-off-by: Jens Axboe

blkmq: Fix NULL pointer deref when all reserved tags in

2015-03-18T23:06:18+00:00

When allocating from the reserved tags pool, bt_get() is called with a NULL hctx. If all tags are in use, the hw queue is kicked to push out any pending IO, potentially freeing tags, and tag allocation is retried. The problem is that blk_mq_run_hw_queue() doesn't check for a NULL hctx. So we avoid it with a simple NULL hctx test. Tested by hammering mtip32xx with concurrent smartctl/hdparm. Signed-off-by: Sam Bradshaw Signed-off-by: Selvan Mani Fixes: b32232073e80 ("blk-mq: fix hang in bt_get()") Cc: stable@kernel.org Added appropriate comment. Signed-off-by: Jens Axboe

blk-mq: fix double-free in error path

2015-02-11T16:35:21+00:00

If the allocation of bt->bs fails, then bt->map can be freed twice, once in blk_mq_init_bitmap_tags() -> bt_alloc(), and once in blk_mq_init_bitmap_tags() -> bt_free(). Fix by setting the pointer to NULL after the first free. Cc: Signed-off-by: Tony Battersby Signed-off-by: Jens Axboe

blk-mq: add tag allocation policy

2015-01-23T21:18:00+00:00

This is the blk-mq part to support tag allocation policy. The default allocation policy isn't changed (though it's not a strict FIFO). The new policy is round-robin for libata. But it's a try-best implementation. If multiple tasks are competing, the tags returned will be mixed (which is unavoidable even with !mq, as requests from different tasks can be mixed in queue) Cc: Jens Axboe Cc: Tejun Heo Cc: Christoph Hellwig Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe

blk-mq: fix false negative out-of-tags condition

2015-01-14T15:49:55+00:00

The blk-mq tagging tries to maintain some locality between CPUs and the tags issued. The tags are split into groups of words, and the words may not be fully populated. When searching for a new free tag, blk-mq may look at partial words, hence it passes in an offset/size to find_next_zero_bit(). However, it does that wrong, the size must always be the full length of the number of tags in that word, otherwise we'll potentially miss some near the end. Another issue is when __bt_get() goes from one word set to the next. It bumps the index, but not the last_tag associated with the previous index. Bump that to be in the range of the new word. Finally, clean up __bt_get() and __bt_get_word() a bit and get rid of the goto in there, and the unnecessary 'wrap' variable. Signed-off-by: Jens Axboe

block: wake up waiters when a queue is marked dying

2014-12-31T16:39:16+00:00

If it's dying, we can't expect new request to complete and come in an wake up other tasks waiting for requests. So after we have marked it as dying, wake up everybody currently waiting for a request. Once they wake, they will retry their allocation and fail appropriately due to the state of the queue. Tested-by: Keith Busch Signed-off-by: Jens Axboe

Revert "blk-mq: Micro-optimize bt_get()"

2014-12-15T15:30:26+00:00

This reverts commit 52f7eb945f2ba62b324bb9ae16d945326a961dcf. The optimization is only really safe for a single queue, otherwise 'bs' and 'bt' can indeed change, and if we don't do a finish_wait() for each loop, we'll potentially change the wait structure and corrupt task wait list. Reported-by: Jan Kara

Merge branch 'for-3.19/core' of git://git.kernel.dk/linux-block

2014-12-13T22:14:23+00:00

Pull block driver core update from Jens Axboe: "This is the pull request for the core block IO changes for 3.19. Not a huge round this time, mostly lots of little good fixes: - Fix a bug in sysfs blktrace interface causing a NULL pointer dereference, when enabled/disabled through that API. From Arianna Avanzini. - Various updates/fixes/improvements for blk-mq: - A set of updates from Bart, mostly fixing buts in the tag handling. - Cleanup/code consolidation from Christoph. - Extend queue_rq API to be able to handle batching issues of IO requests. NVMe will utilize this shortly. From me. - A few tag and request handling updates from me. - Cleanup of the preempt handling for running queues from Paolo. - Prevent running of unmapped hardware queues from Ming Lei. - Move the kdump memory limiting check to be in the correct location, from Shaohua. - Initialize all software queues at init time from Takashi. This prevents a kobject warning when CPUs are brought online that weren't online when a queue was registered. - Single writeback fix for I_DIRTY clearing from Tejun. Queued with the core IO changes, since it's just a single fix. - Version X of the __bio_add_page() segment addition retry from Maurizio. Hope the Xth time is the charm. - Documentation fixup for IO scheduler merging from Jan. - Introduce (and use) generic IO stat accounting helpers for non-rq drivers, from Gu Zheng. - Kill off artificial limiting of max sectors in a request from Christoph" * 'for-3.19/core' of git://git.kernel.dk/linux-block: (26 commits) bio: modify __bio_add_page() to accept pages that don't start a new segment blk-mq: Fix uninitialized kobject at CPU hotplugging blktrace: don't let the sysfs interface remove trace from running list blk-mq: Use all available hardware queues blk-mq: Micro-optimize bt_get() blk-mq: Fix a race between bt_clear_tag() and bt_get() blk-mq: Avoid that __bt_get_word() wraps multiple times blk-mq: Fix a use-after-free blk-mq: prevent unmapped hw queue from being scheduled blk-mq: re-check for available tags after running the hardware queue blk-mq: fix hang in bt_get() blk-mq: move the kdump check to blk_mq_alloc_tag_set blk-mq: cleanup tag free handling blk-mq: use 'nr_cpu_ids' as highest CPU ID count for hwq <-> cpu map blk: introduce generic io stat accounting help function blk-mq: handle the single queue case in blk_mq_hctx_next_cpu genhd: check for int overflow in disk_expand_part_tbl() blk-mq: add blk_mq_free_hctx_request() blk-mq: export blk_mq_free_request() blk-mq: use get_cpu/put_cpu instead of preempt_disable/preempt_enable ...

blk-mq: Micro-optimize bt_get()

2014-12-09T16:07:28+00:00

Remove a superfluous finish_wait() call. Convert the two bt_wait_ptr() calls into a single call. Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Robert Elliott Cc: Ming Lei Cc: Alexander Gordeev Signed-off-by: Jens Axboe

blk-mq: Fix a race between bt_clear_tag() and bt_get()

2014-12-09T16:07:16+00:00

What we need is the following two guarantees: * Any thread that observes the effect of the test_and_set_bit() by __bt_get_word() also observes the preceding addition of 'current' to the appropriate wait list. This is guaranteed by the semantics of the spin_unlock() operation performed by prepare_and_wait(). Hence the conversion of test_and_set_bit_lock() into test_and_set_bit(). * The wait lists are examined by bt_clear() after the tag bit has been cleared. clear_bit_unlock() guarantees that any thread that observes that the bit has been cleared also observes the store operations preceding clear_bit_unlock(). However, clear_bit_unlock() does not prevent that the wait lists are examined before that the tag bit is cleared. Hence the addition of a memory barrier between clear_bit() and the wait list examination. Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Robert Elliott Cc: Ming Lei Cc: Alexander Gordeev Cc: # v3.13+ Signed-off-by: Jens Axboe