talos-obmc-linux/include/linux/elevator.h, branch dev-4.13-fsi

blk-mq-sched: unify request prepare methods

2017-06-18T16:08:55+00:00

This patch makes sure we always allocate requests in the core blk-mq code and use a common prepare_request method to initialize them for both mq I/O schedulers. For Kyber and additional limit_depth method is added that is called before allocating the request. Also because none of the intializations can really fail the new method does not return an error - instead the bfq finish method is hardened to deal with the no-IOC case. Last but not least this removes the abuse of RQF_QUEUE by the blk-mq scheduling code as RQF_ELFPRIV is all that is needed now. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe

blk-mq-sched: unify request finished methods

2017-06-18T16:08:55+00:00

No need to have two different callouts of bfq vs kyber. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe

elevator: fix truncation of icq_cache_name

2017-06-06T17:20:47+00:00

gcc 7.1 reports the following warning: block/elevator.c: In function ‘elv_register’: block/elevator.c:898:5: warning: ‘snprintf’ output may be truncated before the last format character [-Wformat-truncation=] "%s_io_cq", e->elevator_name); ^~~~~~~~~~ block/elevator.c:897:3: note: ‘snprintf’ output between 7 and 22 bytes into a destination of size 21 snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "%s_io_cq", e->elevator_name); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The bug is that the name of the icq_cache is 6 characters longer than the elevator name, but only ELV_NAME_MAX + 5 characters were reserved for it --- so in the case of a maximum-length elevator name, the 'q' character in "_io_cq" would be truncated by snprintf(). Fix it by reserving ELV_NAME_MAX + 6 characters instead. Signed-off-by: Eric Biggers Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe

blk-mq-debugfs: allow schedulers to register debugfs attributes

2017-05-04T14:24:40+00:00

This provides the infrastructure for schedulers to expose their internal state through debugfs. We add a list of queue attributes and a list of hctx attributes to struct elevator_type and wire them up when switching schedulers. Signed-off-by: Omar Sandoval Reviewed-by: Hannes Reinecke Add missing seq_file.h header in blk-mq-debugfs.h Signed-off-by: Jens Axboe

block: Remove elevator_change()

2017-05-02T13:52:08+00:00

Since commit 84253394927c ("remove the mg_disk driver") removed the only caller of elevator_change(), also remove the elevator_change() function itself. Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Markus Trippelsdorf Signed-off-by: Jens Axboe

blk-mq-sched: make completed_request() callback more useful

2017-04-14T20:06:57+00:00

Currently, this callback is called right after put_request() and has no distinguishable purpose. Instead, let's call it before put_request() as soon as I/O has completed on the request, before we account it in blk-stat. With this, Kyber can enable stats when it sees a latency outlier and make sure the outlier gets accounted. Signed-off-by: Omar Sandoval Signed-off-by: Jens Axboe

blk-mq-sched: provide hooks for initializing hardware queue data

2017-04-07T18:45:41+00:00

Schedulers need to be informed when a hardware queue is added or removed at runtime so they can allocate/free per-hardware queue data. So, replace the blk_mq_sched_init_hctx_data() helper, which only makes sense at init time, with .init_hctx() and .exit_hctx() hooks. Signed-off-by: Omar Sandoval Signed-off-by: Jens Axboe

blk-mq-sched: fix crash in switch error path

2017-04-07T14:56:48+00:00

In elevator_switch(), if blk_mq_init_sched() fails, we attempt to fall back to the original scheduler. However, at this point, we've already torn down the original scheduler's tags, so this causes a crash. Doing the fallback like the legacy elevator path is much harder for mq, so fix it by just falling back to none, instead. Signed-off-by: Omar Sandoval Signed-off-by: Jens Axboe

blk-mq: pass bio to blk_mq_sched_get_rq_priv

2017-02-10T16:09:59+00:00

bio is used in bfq-mq's get_rq_priv, to get the request group. We could pass directly the group here, but I thought that passing the bio was more general, giving the possibility to get other pieces of information if needed. Signed-off-by: Paolo Valente Signed-off-by: Jens Axboe

block: optionally merge discontiguous discard bios into a single request

2017-02-08T20:43:08+00:00

Add a new merge strategy that merges discard bios into a request until the maximum number of discard ranges (or the maximum discard size) is reached from the plug merging code. I/O scheduler merging is not wired up yet but might also be useful, although not for fast devices like NVMe which are the only user for now. Note that for now we don't support limiting the size of each discard range, but if needed that can be added later. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe