linux/drivers/block/loop.c, branch v4.7

Merge branch 'for-4.7/drivers' of git://git.kernel.dk/linux-block

2016-05-17T23:03:32Z

Pull block driver updates from Jens Axboe: "On top of the core pull request, this is the drivers pull request for this merge window. This contains: - Switch drivers to the new write back cache API, and kill off the flush flags. From me. - Kill the discard support for the STEC pci-e flash driver. It's trivially broken, and apparently unmaintained, so it's safer to just remove it. From Jeff Moyer. - A set of lightnvm updates from the usual suspects (Matias/Javier, and Simon), and fixes from Arnd, Jeff Mahoney, Sagi, and Wenwei Tao. - A set of updates for NVMe: - Turn the controller state management into a proper state machine. From Christoph. - Shuffling of code in preparation for NVMe-over-fabrics, also from Christoph. - Cleanup of the command prep part from Ming Lin. - Rewrite of the discard support from Ming Lin. - Deadlock fix for namespace removal from Ming Lin. - Use the now exported blk-mq tag helper for IO termination. From Sagi. - Various little fixes from Christoph, Guilherme, Keith, Ming Lin, Wang Sheng-Hui. - Convert mtip32xx to use the now exported blk-mq tag iter function, from Keith" * 'for-4.7/drivers' of git://git.kernel.dk/linux-block: (74 commits) lightnvm: reserved space calculation incorrect lightnvm: rename nr_pages to nr_ppas on nvm_rq lightnvm: add is_cached entry to struct ppa_addr lightnvm: expose gennvm_mark_blk to targets lightnvm: remove mgt targets on mgt removal lightnvm: pass dma address to hardware rather than pointer lightnvm: do not assume sequential lun alloc. nvme/lightnvm: Log using the ctrl named device lightnvm: rename dma helper functions lightnvm: enable metadata to be sent to device lightnvm: do not free unused metadata on rrpc lightnvm: fix out of bound ppa lun id on bb tbl lightnvm: refactor set_bb_tbl for accepting ppa list lightnvm: move responsibility for bad blk mgmt to target lightnvm: make nvm_set_rqd_ppalist() aware of vblks lightnvm: remove struct factory_blks lightnvm: refactor device ops->get_bb_tbl() lightnvm: introduce nvm_for_each_lun_ppa() macro lightnvm: refactor dev->online_target to global nvm_targets lightnvm: rename nvm_targets to nvm_tgt_type ...

block: loop: fix filesystem corruption in case of aio/dio

2016-04-15T14:25:56Z

Starting from commit e36f620428(block: split bios to max possible length), block core starts to split bio in the middle of bvec. Unfortunately loop dio/aio doesn't consider this situation, and always treat 'iter.iov_offset' as zero. Then filesystem corruption is observed. This patch figures out the offset of the base bvevc via 'bio->bi_iter.bi_bvec_done' and fixes the issue by passing the offset to iov iterator. Fixes: e36f6204288088f (block: split bios to max possible length) Cc: Keith Busch Cc: Al Viro Cc: stable@vger.kernel.org (4.5) Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

loop: switch to using blk_queue_write_cache()

2016-04-12T22:00:39Z

Signed-off-by: Jens Axboe Reviewed-by: Christoph Hellwig

Merge branch 'for-4.4/core' into for-4.4/drivers

2015-10-09T16:40:29Z

Signed-off-by: Jens Axboe

blk-mq: fix racy updates of rq->errors

2015-10-01T08:10:55Z

blk_mq_complete_request may be a no-op if the request has already been completed by others means (e.g. a timeout or cancellation), but currently drivers have to set rq->errors before calling blk_mq_complete_request, which might leave us with the wrong error value. Add an error parameter to blk_mq_complete_request so that we can defer setting rq->errors until we known we won the race to complete the request. Signed-off-by: Christoph Hellwig Reviewed-by: Sagi Grimberg Signed-off-by: Jens Axboe

block: loop: support DIO & AIO

2015-09-23T17:01:16Z

There are at least 3 advantages to use direct I/O and AIO on read/write loop's backing file: 1) double cache can be avoided, then memory usage gets decreased a lot 2) not like user space direct I/O, there isn't cost of pinning pages 3) avoid context switch for obtaining good throughput - in buffered file read, random I/O top throughput is often obtained only if they are submitted concurrently from lots of tasks; but for sequential I/O, most of times they can be hit from page cache, so concurrent submissions often introduce unnecessary context switch and can't improve throughput much. There was such discussion[1] to use non-blocking I/O to improve the problem for application. - with direct I/O and AIO, concurrent submissions can be avoided and random read throughput can't be affected meantime xfstests(-g auto, ext4) is basically passed when running with direct I/O(aio), one exception is generic/232, but it failed in loop buffered I/O(4.2-rc6-next-20150814) too. Follows the fio test result for performance purpose: 4 jobs fio test inside ext4 file system over loop block 1) How to run - KVM: 4 VCPUs, 2G RAM - linux kernel: 4.2-rc6-next-20150814(base) with the patchset - the loop block is over one image on SSD. - linux psync, 4 jobs, size 1500M, ext4 over loop block - test result: IOPS from fio output 2) Throughput(IOPS) becomes a bit better with direct I/O(aio) ------------------------------------------------------------- test cases |randread |read |randwrite |write | ------------------------------------------------------------- base |8015 |113811 |67442 |106978 ------------------------------------------------------------- base+loop aio |8136 |125040 |67811 |111376 ------------------------------------------------------------- - somehow, it should be caused by more page cache avaiable for application or one extra page copy is avoided in case of direct I/O 3) context switch - context switch decreased by ~50% with loop direct I/O(aio) compared with loop buffered I/O(4.2-rc6-next-20150814) 4) memory usage from /proc/meminfo ------------------------------------------------------------- | Buffers | Cached ------------------------------------------------------------- base | > 760MB | ~950MB ------------------------------------------------------------- base+loop direct I/O(aio) | < 5MB | ~1.6GB ------------------------------------------------------------- - so there are much more page caches available for application with direct I/O [1] https://lwn.net/Articles/612483/ Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

block: loop: introduce ioctl command of LOOP_SET_DIRECT_IO

2015-09-23T17:01:16Z

If loop block is mounted via 'mount -o loop', it isn't easy to pass file descriptor opened as O_DIRECT, so this patch introduces a new command to support direct IO for this case. Cc: linux-api@vger.kernel.org Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

block: loop: prepare for supporing direct IO

2015-09-23T17:01:16Z

This patches provides one interface for enabling direct IO from user space: - userspace(such as losetup) can pass 'file' which is opened/fcntl as O_DIRECT Also __loop_update_dio() is introduced to check if direct I/O can be used on current loop setting. The last big change is to introduce LO_FLAGS_DIRECT_IO flag for userspace to know if direct IO is used to access backing file. Cc: linux-api@vger.kernel.org Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

block: loop: use kthread_work

2015-09-23T17:01:16Z

The following patch will use dio/aio to submit IO to backing file, then it needn't to schedule IO concurrently from work, so use kthread_work for decreasing context switch cost a lot. For non-AIO case, single thread has been used for long long time, and it was just converted to work in v4.0, which has caused performance regression for fedora live booting already. In discussion[1], even though submitting I/O via work concurrently can improve random read IO throughput, meantime it might hurt sequential read IO performance, so better to restore to single thread behaviour. For the following AIO support, it is better to use multi hw-queue with per-hwq kthread than current work approach suppose there is so high performance requirement for loop. [1] http://marc.info/?t=143082678400002&r=1&w=2 Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

block: loop: set QUEUE_FLAG_NOMERGES for request queue of loop

2015-09-23T17:01:16Z

It doesn't make sense to enable merge because the I/O submitted to backing file is handled page by page. Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe