- 06 Mar, 2019 2 commits
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Jens Axboe authored
Right now we punt any buffered request that ends up triggering an -EAGAIN to an async workqueue. This works fine in terms of providing async execution of them, but it also can create quite a lot of work queue items. For sequentially buffered IO, it's advantageous to serialize the issue of them. For reads, the first one will trigger a read-ahead, and subsequent request merely end up waiting on later pages to complete. For writes, devices usually respond better to streamed sequential writes. Add state to track the last buffered request we punted to a work queue, and if the next one is sequential to the previous, attempt to get the previous work item to handle it. We limit the number of sequential add-ons to the a multiple (8) of the max read-ahead size of the file. This should be a good number for both reads and wries, as it defines the max IO size the device can do directly. This drastically cuts down on the number of context switches we need to handle buffered sequential IO, and a basic test case of copying a big file with io_uring sees a 5x speedup. Reviewed-by:
Hannes Reinecke <hare@suse.com> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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Jens Axboe authored
This is basically a direct port of bfe4037e, which implements a one-shot poll command through aio. Description below is based on that commit as well. However, instead of adding a POLL command and relying on io_cancel(2) to remove it, we mimic the epoll(2) interface of having a command to add a poll notification, IORING_OP_POLL_ADD, and one to remove it again, IORING_OP_POLL_REMOVE. To poll for a file descriptor the application should submit an sqe of type IORING_OP_POLL. It will poll the fd for the events specified in the poll_events field. Unlike poll or epoll without EPOLLONESHOT this interface always works in one shot mode, that is once the sqe is completed, it will have to be resubmitted. Reviewed-by:
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- 28 Feb, 2019 13 commits
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Jens Axboe authored
We'll use this for the POLL implementation. Regular requests will NOT be using references, so initialize it to 0. Any real use of the io_kiocb ref will initialize it to at least 2. Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
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Jens Axboe authored
This enables an application to do IO, without ever entering the kernel. By using the SQ ring to fill in new sqes and watching for completions on the CQ ring, we can submit and reap IOs without doing a single system call. The kernel side thread will poll for new submissions, and in case of HIPRI/polled IO, it'll also poll for completions. By default, we allow 1 second of active spinning. This can by changed by passing in a different grace period at io_uring_register(2) time. If the thread exceeds this idle time without having any work to do, it will set: sq_ring->flags |= IORING_SQ_NEED_WAKEUP. The application will have to call io_uring_enter() to start things back up again. If IO is kept busy, that will never be needed. Basically an application that has this feature enabled will guard it's io_uring_enter(2) call with: read_barrier(); if (*sq_ring->flags & IORING_SQ_NEED_WAKEUP) io_uring_enter(fd, 0, 0, IORING_ENTER_SQ_WAKEUP); instead of calling it unconditionally. It's mandatory to use fixed files with this feature. Failure to do so will result in the application getting an -EBADF CQ entry when submitting IO. Reviewed-by:
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Jens Axboe authored
We normally have to fget/fput for each IO we do on a file. Even with the batching we do, the cost of the atomic inc/dec of the file usage count adds up. This adds IORING_REGISTER_FILES, and IORING_UNREGISTER_FILES opcodes for the io_uring_register(2) system call. The arguments passed in must be an array of __s32 holding file descriptors, and nr_args should hold the number of file descriptors the application wishes to pin for the duration of the io_uring instance (or until IORING_UNREGISTER_FILES is called). When used, the application must set IOSQE_FIXED_FILE in the sqe->flags member. Then, instead of setting sqe->fd to the real fd, it sets sqe->fd to the index in the array passed in to IORING_REGISTER_FILES. Files are automatically unregistered when the io_uring instance is torn down. An application need only unregister if it wishes to register a new set of fds. Reviewed-by:
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Jens Axboe authored
We need this functionality for the io_uring file registration, but we cannot rely on it since CONFIG_UNIX can be modular. Move the helpers to a separate file, that's always builtin to the kernel if CONFIG_UNIX is m/y. No functional changes in this patch, just moving code around. Reviewed-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
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Jens Axboe authored
If we have fixed user buffers, we can map them into the kernel when we setup the io_uring. That avoids the need to do get_user_pages() for each and every IO. To utilize this feature, the application must call io_uring_register() after having setup an io_uring instance, passing in IORING_REGISTER_BUFFERS as the opcode. The argument must be a pointer to an iovec array, and the nr_args should contain how many iovecs the application wishes to map. If successful, these buffers are now mapped into the kernel, eligible for IO. To use these fixed buffers, the application must use the IORING_OP_READ_FIXED and IORING_OP_WRITE_FIXED opcodes, and then set sqe->index to the desired buffer index. sqe->addr..sqe->addr+seq->len must point to somewhere inside the indexed buffer. The application may register buffers throughout the lifetime of the io_uring instance. It can call io_uring_register() with IORING_UNREGISTER_BUFFERS as the opcode to unregister the current set of buffers, and then register a new set. The application need not unregister buffers explicitly before shutting down the io_uring instance. It's perfectly valid to setup a larger buffer, and then sometimes only use parts of it for an IO. As long as the range is within the originally mapped region, it will work just fine. For now, buffers must not be file backed. If file backed buffers are passed in, the registration will fail with -1/EOPNOTSUPP. This restriction may be relaxed in the future. RLIMIT_MEMLOCK is used to check how much memory we can pin. A somewhat arbitrary 1G per buffer size is also imposed. Reviewed-by:
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Jens Axboe authored
For an ITER_BVEC, we can just iterate the iov and add the pages to the bio directly. For now, we grab a reference to those pages, and release them normally on IO completion. This isn't really needed for the normal case of O_DIRECT from/to a file, but some of the more esoteric use cases (like splice(2)) will unconditionally put the pipe buffer pages when the buffers are released. Until we can manage that case properly, ITER_BVEC pages are treated like normal pages in terms of reference counting. Reviewed-by:
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Jens Axboe authored
Similarly to how we use the state->ios_left to know how many references to get to a file, we can use it to allocate the io_kiocb's we need in bulk. Reviewed-by:
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Jens Axboe authored
Add a separate io_submit_state structure, to cache some of the things we need for IO submission. One such example is file reference batching. io_submit_state. We get as many references as the number of sqes we are submitting, and drop unused ones if we end up switching files. The assumption here is that we're usually only dealing with one fd, and if there are multiple, hopefuly they are at least somewhat ordered. Could trivially be extended to cover multiple fds, if needed. On the completion side we do the same thing, except this is trivially done just locally in io_iopoll_reap(). Reviewed-by:
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Jens Axboe authored
Some uses cases repeatedly get and put references to the same file, but the only exposed interface is doing these one at the time. As each of these entail an atomic inc or dec on a shared structure, that cost can add up. Add fget_many(), which works just like fget(), except it takes an argument for how many references to get on the file. Ditto fput_many(), which can drop an arbitrary number of references to a file. Reviewed-by:
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Jens Axboe authored
Add support for a polled io_uring instance. When a read or write is submitted to a polled io_uring, the application must poll for completions on the CQ ring through io_uring_enter(2). Polled IO may not generate IRQ completions, hence they need to be actively found by the application itself. To use polling, io_uring_setup() must be used with the IORING_SETUP_IOPOLL flag being set. It is illegal to mix and match polled and non-polled IO on an io_uring. Reviewed-by:
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Christoph Hellwig authored
Add a new fsync opcode, which either syncs a range if one is passed, or the whole file if the offset and length fields are both cleared to zero. A flag is provided to use fdatasync semantics, that is only force out metadata which is required to retrieve the file data, but not others like metadata. Reviewed-by:
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Jens Axboe authored
The submission queue (SQ) and completion queue (CQ) rings are shared between the application and the kernel. This eliminates the need to copy data back and forth to submit and complete IO. IO submissions use the io_uring_sqe data structure, and completions are generated in the form of io_uring_cqe data structures. The SQ ring is an index into the io_uring_sqe array, which makes it possible to submit a batch of IOs without them being contiguous in the ring. The CQ ring is always contiguous, as completion events are inherently unordered, and hence any io_uring_cqe entry can point back to an arbitrary submission. Two new system calls are added for this: io_uring_setup(entries, params) Sets up an io_uring instance for doing async IO. On success, returns a file descriptor that the application can mmap to gain access to the SQ ring, CQ ring, and io_uring_sqes. io_uring_enter(fd, to_submit, min_complete, flags, sigset, sigsetsize) Initiates IO against the rings mapped to this fd, or waits for them to complete, or both. The behavior is controlled by the parameters passed in. If 'to_submit' is non-zero, then we'll try and submit new IO. If IORING_ENTER_GETEVENTS is set, the kernel will wait for 'min_complete' events, if they aren't already available. It's valid to set IORING_ENTER_GETEVENTS and 'min_complete' == 0 at the same time, this allows the kernel to return already completed events without waiting for them. This is useful only for polling, as for IRQ driven IO, the application can just check the CQ ring without entering the kernel. With this setup, it's possible to do async IO with a single system call. Future developments will enable polled IO with this interface, and polled submission as well. The latter will enable an application to do IO without doing ANY system calls at all. For IRQ driven IO, an application only needs to enter the kernel for completions if it wants to wait for them to occur. Each io_uring is backed by a workqueue, to support buffered async IO as well. We will only punt to an async context if the command would need to wait for IO on the device side. Any data that can be accessed directly in the page cache is done inline. This avoids the slowness issue of usual threadpools, since cached data is accessed as quickly as a sync interface. Sample application: http://git.kernel.dk/cgit/fio/plain/t/io_uring.cReviewed-by:
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Ming Lei authored
mp_bvec_for_each_segment() is a bit big for the iteration, so introduce a light-weight helper for iterating over pages, then 32bytes stack space can be saved. Signed-off-by:
Ming Lei <ming.lei@redhat.com> Signed-off-by:
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- 27 Feb, 2019 3 commits
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Ming Lei authored
Introduce a fast path for single-page bvec IO, then we can avoid to call bvec_split_segs() unnecessarily. Signed-off-by:
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Ming Lei authored
Introduce a fast path for single-page bvec IO, then blk_bvec_map_sg() can be avoided. Signed-off-by:
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Ming Lei authored
Single-page bvec can often be seen in small BS workloads, so introduce bvec_nth_page() for avoiding to call nth_page() unnecessarily, which looks not cheap. Signed-off-by:
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- 24 Feb, 2019 4 commits
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Christoph Hellwig authored
Store the request queue the last bio was submitted to in the iocb private data in addition to the cookie so that we find the right block device. Also refactor the common direct I/O bio submission code into a nice little helper. Signed-off-by:
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Jens Axboe authored
For the upcoming async polled IO, we can't sleep allocating requests. If we do, then we introduce a deadlock where the submitter already has async polled IO in-flight, but can't wait for them to complete since polled requests must be active found and reaped. Utilize the helper in the blockdev DIRECT_IO code. Reviewed-by:
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Christoph Hellwig authored
Just call blk_poll on the iocb cookie, we can derive the block device from the inode trivially. Reviewed-by:
Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by:
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Christoph Hellwig authored
This new methods is used to explicitly poll for I/O completion for an iocb. It must be called for any iocb submitted asynchronously (that is with a non-null ki_complete) which has the IOCB_HIPRI flag set. The method is assisted by a new ki_cookie field in struct iocb to store the polling cookie. Reviewed-by:
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- 22 Feb, 2019 2 commits
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Dongli Zhang authored
Commit 0da03cab ("loop: Fix deadlock when calling blkdev_reread_part()") moves blkdev_reread_part() out of the loop_ctl_mutex. However, GENHD_FL_NO_PART_SCAN is set before __blkdev_reread_part(). As a result, __blkdev_reread_part() will fail the check of GENHD_FL_NO_PART_SCAN and will not rescan the loop device to delete all partitions. Below are steps to reproduce the issue: step1 # dd if=/dev/zero of=tmp.raw bs=1M count=100 step2 # losetup -P /dev/loop0 tmp.raw step3 # parted /dev/loop0 mklabel gpt step4 # parted -a none -s /dev/loop0 mkpart primary 64s 1 step5 # losetup -d /dev/loop0 Step5 will not be able to delete /dev/loop0p1 (introduced by step4) and there is below kernel warning message: [ 464.414043] __loop_clr_fd: partition scan of loop0 failed (rc=-22) This patch sets GENHD_FL_NO_PART_SCAN after blkdev_reread_part(). Fixes: 0da03cab ("loop: Fix deadlock when calling blkdev_reread_part()") Signed-off-by:
Dongli Zhang <dongli.zhang@oracle.com> Reviewed-by:
Jan Kara <jack@suse.cz> Signed-off-by:
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Dongli Zhang authored
Do not print warn message when the partition scan returns 0. Fixes: d57f3374 ("loop: Move special partition reread handling in loop_clr_fd()") Signed-off-by:
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- 21 Feb, 2019 3 commits
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Ming Lei authored
Block bounce needs to allocate new page for doing IO, and the new page has to be updated to bvec table. Commit 6dc4f100 switches __blk_queue_bounce() to use the new bio_for_each_segment_all() interface. Unfortunately the new bio_for_each_segment_all() can't be used to update bvec table. This patch fixes this issue by retrieving bvec from the table directly, then the new allocated page can be updated to the bio. This way is safe because the cloned bio is single page bvec. Fixes: 6dc4f100 ("block: allow bio_for_each_segment_all() to iterate over multi-page bvec") Cc: Christoph Hellwig <hch@lst.de> Cc: Omar Sandoval <osandov@fb.com> Signed-off-by:
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git://git.infradead.org/nvmeJens Axboe authored
Pull NVMe changes for 5.1 from Christoph * 'nvme-5.1' of git://git.infradead.org/nvme: (22 commits) nvme-rdma: use nr_phys_segments when map rq to sgl nvmet: convert to SPDX identifiers nvmet-rdma: convert to SPDX identifiers nvme-loop: convert to SPDX identifiers nvmet-fcloop: convert to SPDX identifiers nvmet-fc: convert to SPDX identifiers nvme: convert to SPDX identifiers nvme-pci: convert to SPDX identifiers nvme-lightnvm: convert to SPDX identifiers nvme-rdma: convert to SPDX identifiers nvme-fc: convert to SPDX identifiers nvme-fabrics: convert to SPDX identifiers nvme-tcp.h: fix SPDX header nvme_ioctl.h: remove duplicate GPL boilerplate nvme: return error from nvme_alloc_ns() nvme: avoid that deleting a controller triggers a circular locking complaint nvme: introduce a helper function for controller deletion nvme: unexport nvme_delete_ctrl_sync() nvme-pci: check kstrtoint() return value in queue_count_set() nvme-fabrics: document the poll function argument ...
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Chaitanya Kulkarni authored
Use blk_rq_nr_phys_segments() instead of blk_rq_payload_bytes() to check if a command contains data to be mapped. This fixes the case where a struct request contains LBAs, but it has no payload, such as Write Zeroes support. Fixes: 6e02318e ("nvme: add support for the Write Zeroes command") Reported-by:
Ming Lei <tom.leiming@gmail.com> Signed-off-by:
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Tested-by:
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- 20 Feb, 2019 13 commits
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
Sagi Grimberg <sagi@grimberg.me>
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
Update license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by:
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Christoph Hellwig authored
For .h files we need to use /* */ style comments. Signed-off-by:
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Christoph Hellwig authored
We already have a ЅPDX header, so no need to duplicate the information. Signed-off-by:
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