user/sven/linux.git/include/linux/blkdev.h, branch v3.17

blk-mq: use percpu_ref for mq usage count

2014-07-01T16:34:38Z

Currently, blk-mq uses a percpu_counter to keep track of how many usages are in flight. The percpu_counter is drained while freezing to ensure that no usage is left in-flight after freezing is complete. blk_mq_queue_enter/exit() and blk_mq_[un]freeze_queue() implement this per-cpu gating mechanism. This type of code has relatively high chance of subtle bugs which are extremely difficult to trigger and it's way too hairy to be open coded in blk-mq. percpu_ref can serve the same purpose after the recent changes. This patch replaces the open-coded per-cpu usage counting and draining mechanism with percpu_ref. blk_mq_queue_enter() performs tryget_live on the ref and exit() performs put. blk_mq_freeze_queue() kills the ref and waits until the reference count reaches zero. blk_mq_unfreeze_queue() revives the ref and wakes up the waiters. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Nicholas A. Bellinger Cc: Kent Overstreet Signed-off-by: Jens Axboe

blk-mq: decouble blk-mq freezing from generic bypassing

2014-07-01T16:31:13Z

blk_mq freezing is entangled with generic bypassing which bypasses blkcg and io scheduler and lets IO requests fall through the block layer to the drivers in FIFO order. This allows forward progress on IOs with the advanced features disabled so that those features can be configured or altered without worrying about stalling IO which may lead to deadlock through memory allocation. However, generic bypassing doesn't quite fit blk-mq. blk-mq currently doesn't make use of blkcg or ioscheds and it maps bypssing to freezing, which blocks request processing and drains all the in-flight ones. This causes problems as bypassing assumes that request processing is online. blk-mq works around this by conditionally allowing request processing for the problem case - during queue initialization. Another weirdity is that except for during queue cleanup, bypassing started on the generic side prevents blk-mq from processing new requests but doesn't drain the in-flight ones. This shouldn't break anything but again highlights that something isn't quite right here. The root cause is conflating blk-mq freezing and generic bypassing which are two different mechanisms. The only intersecting purpose that they serve is during queue cleanup. Let's properly separate blk-mq freezing from generic bypassing and simply use it where necessary. * request_queue->mq_freeze_depth is added and blk_mq_[un]freeze_queue() now operate on this counter instead of ->bypass_depth. The replacement for QUEUE_FLAG_BYPASS isn't added but the counter is tested directly. This will be further updated by later changes. * blk_mq_drain_queue() is dropped and "__" prefix is dropped from blk_mq_freeze_queue(). Queue cleanup path now calls blk_mq_freeze_queue() directly. * blk_queue_enter()'s fast path condition is simplified to simply check @q->mq_freeze_depth. Previously, the condition was !blk_queue_dying(q) && (!blk_queue_bypass(q) || !blk_queue_init_done(q)) mq_freeze_depth is incremented right after dying is set and blk_queue_init_done() exception isn't necessary as blk-mq doesn't start frozen, which only leaves the blk_queue_bypass() test which can be replaced by @q->mq_freeze_depth test. This change simplifies the code and reduces confusion in the area. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Nicholas A. Bellinger Signed-off-by: Jens Axboe

block: add support for limiting gaps in SG lists

2014-06-24T22:22:24Z

Another restriction inherited for NVMe - those devices don't support SG lists that have "gaps" in them. Gaps refers to cases where the previous SG entry doesn't end on a page boundary. For NVMe, all SG entries must start at offset 0 (except the first) and end on a page boundary (except the last). Signed-off-by: Jens Axboe

block: blk_max_size_offset() should check ->max_sectors

2014-06-18T05:12:02Z

Commit 762380ad9322 inadvertently changed a check for max_sectors to max_hw_sectors. Revert that part, so we still compare against max_sectors. Signed-off-by: Jens Axboe

block: add blk_rq_set_block_pc()

2014-06-06T13:57:37Z

With the optimizations around not clearing the full request at alloc time, we are leaving some of the needed init for REQ_TYPE_BLOCK_PC up to the user allocating the request. Add a blk_rq_set_block_pc() that sets the command type to REQ_TYPE_BLOCK_PC, and properly initializes the members associated with this type of request. Update callers to use this function instead of manipulating rq->cmd_type directly. Includes fixes from Christoph Hellwig for my half-assed attempt. Signed-off-by: Jens Axboe

block: add notion of a chunk size for request merging

2014-06-05T19:38:39Z

Some drivers have different limits on what size a request should optimally be, depending on the offset of the request. Similar to dividing a device into chunks. Add a setting that allows the driver to inform the block layer of such a chunk size. The block layer will then prevent merging across the chunks. This is needed to optimally support NVMe with a non-zero stripe size. Signed-off-by: Jens Axboe

Merge branch 'akpm' (patchbomb from Andrew) into next

2014-06-04T23:55:13Z

Merge misc updates from Andrew Morton: - a few fixes for 3.16. Cc'ed to stable so they'll get there somehow. - various misc fixes and cleanups - most of the ocfs2 queue. Review is slow... - most of MM. The MM queue is pretty huge this time, but not much in the way of feature work. - some tweaks under kernel/ - printk maintenance work - updates to lib/ - checkpatch updates - tweaks to init/ * emailed patches from Andrew Morton : (276 commits) fs/autofs4/dev-ioctl.c: add __init to autofs_dev_ioctl_init fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul init/main.c: remove an ifdef kthreads: kill CLONE_KERNEL, change kernel_thread(kernel_init) to avoid CLONE_SIGHAND init/main.c: add initcall_blacklist kernel parameter init/main.c: don't use pr_debug() fs/binfmt_flat.c: make old_reloc() static fs/binfmt_elf.c: fix bool assignements fs/efs: convert printk(KERN_DEBUG to pr_debug fs/efs: add pr_fmt / use __func__ fs/efs: convert printk to pr_foo() scripts/checkpatch.pl: device_initcall is not the only __initcall substitute checkpatch: check stable email address checkpatch: warn on unnecessary void function return statements checkpatch: prefer kstrto to sscanf(buf, "%", &bar); checkpatch: add warning for kmalloc/kzalloc with multiply checkpatch: warn on #defines ending in semicolon checkpatch: make --strict a default for files in drivers/net and net/ checkpatch: always warn on missing blank line after variable declaration block checkpatch: fix wildcard DT compatible string checking ...

fs/block_dev.c: add bdev_read_page() and bdev_write_page()

2014-06-04T23:54:02Z

A block device driver may choose to provide a rw_page operation. These will be called when the filesystem is attempting to do page sized I/O to page cache pages (ie not for direct I/O). This does preclude I/Os that are larger than page size, so this may only be a performance gain for some devices. Signed-off-by: Matthew Wilcox Tested-by: Dheeraj Reddy Cc: Dave Chinner Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs/libfs.c: add generic data flush to fsync

2014-06-04T23:53:55Z

Description by Jan Kara: "A lot of older filesystems don't properly flush volatile disk caches on fsync(2) which can lead to loss of fsynced data after power failure. This patch makes generic_file_fsync() issue proper cache flush to fix the problem. Sysadmin can use /sys/devices/.../cache_type to tell the system it should not send the cache flush." [akpm@linux-foundation.org: nuke ifdef] [akpm@linux-foundation.org: fix warning] Signed-off-by: Fabian Frederick Suggested-by: Jan Kara Suggested-by: Christoph Hellwig Cc: Jan Kara Cc: Christoph Hellwig Cc: Alexander Viro Cc: "Theodore Ts'o" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

blk-mq: fix sparse warning on missed __percpu annotation

2014-06-04T03:04:39Z

'struct blk_mq_ctx' is __percpu, so add the annotation and fix the sparse warning reported from Fengguang: [block:for-linus 2/3] block/blk-mq.h:75:16: sparse: incorrect type in initializer (different address spaces) Reported-by: kbuild test robot Signed-off-by: Ming Lei Signed-off-by: Jens Axboe