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![Jens Axboe](/assets/img/avatar_default.png)
If IOCB_DIO_CALLER_COMP is set, utilize that to set kiocb->dio_complete handler and data for that callback. Rather than punt the completion to a workqueue, we pass back the handler and data to the issuer and will get a callback from a safe task context. Using the following fio job to randomly dio write 4k blocks at queue depths of 1..16: fio --name=dio-write --filename=/data1/file --time_based=1 \ --runtime=10 --bs=4096 --rw=randwrite --norandommap --buffered=0 \ --cpus_allowed=4 --ioengine=io_uring --iodepth=$depth shows the following results before and after this patch: Stock Patched Diff ======================================= QD1 155K 162K + 4.5% QD2 290K 313K + 7.9% QD4 533K 597K +12.0% QD8 604K 827K +36.9% QD16 615K 845K +37.4% which shows nice wins all around. If we factored in per-IOP efficiency, the wins look even nicer. This becomes apparent as queue depth rises, as the offloaded workqueue completions runs out of steam. Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
754 lines
21 KiB
C
754 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2010 Red Hat, Inc.
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* Copyright (c) 2016-2021 Christoph Hellwig.
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*/
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#include <linux/module.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/fscrypt.h>
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#include <linux/pagemap.h>
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#include <linux/iomap.h>
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#include <linux/backing-dev.h>
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#include <linux/uio.h>
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#include <linux/task_io_accounting_ops.h>
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#include "trace.h"
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#include "../internal.h"
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/*
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* Private flags for iomap_dio, must not overlap with the public ones in
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* iomap.h:
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*/
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#define IOMAP_DIO_CALLER_COMP (1U << 26)
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#define IOMAP_DIO_INLINE_COMP (1U << 27)
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#define IOMAP_DIO_WRITE_THROUGH (1U << 28)
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#define IOMAP_DIO_NEED_SYNC (1U << 29)
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#define IOMAP_DIO_WRITE (1U << 30)
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#define IOMAP_DIO_DIRTY (1U << 31)
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struct iomap_dio {
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struct kiocb *iocb;
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const struct iomap_dio_ops *dops;
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loff_t i_size;
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loff_t size;
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atomic_t ref;
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unsigned flags;
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int error;
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size_t done_before;
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bool wait_for_completion;
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union {
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/* used during submission and for synchronous completion: */
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struct {
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struct iov_iter *iter;
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struct task_struct *waiter;
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} submit;
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/* used for aio completion: */
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struct {
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struct work_struct work;
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} aio;
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};
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};
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static struct bio *iomap_dio_alloc_bio(const struct iomap_iter *iter,
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struct iomap_dio *dio, unsigned short nr_vecs, blk_opf_t opf)
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{
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if (dio->dops && dio->dops->bio_set)
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return bio_alloc_bioset(iter->iomap.bdev, nr_vecs, opf,
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GFP_KERNEL, dio->dops->bio_set);
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return bio_alloc(iter->iomap.bdev, nr_vecs, opf, GFP_KERNEL);
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}
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static void iomap_dio_submit_bio(const struct iomap_iter *iter,
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struct iomap_dio *dio, struct bio *bio, loff_t pos)
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{
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struct kiocb *iocb = dio->iocb;
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atomic_inc(&dio->ref);
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/* Sync dio can't be polled reliably */
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if ((iocb->ki_flags & IOCB_HIPRI) && !is_sync_kiocb(iocb)) {
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bio_set_polled(bio, iocb);
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WRITE_ONCE(iocb->private, bio);
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}
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if (dio->dops && dio->dops->submit_io)
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dio->dops->submit_io(iter, bio, pos);
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else
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submit_bio(bio);
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}
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ssize_t iomap_dio_complete(struct iomap_dio *dio)
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{
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const struct iomap_dio_ops *dops = dio->dops;
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struct kiocb *iocb = dio->iocb;
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loff_t offset = iocb->ki_pos;
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ssize_t ret = dio->error;
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if (dops && dops->end_io)
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ret = dops->end_io(iocb, dio->size, ret, dio->flags);
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if (likely(!ret)) {
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ret = dio->size;
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/* check for short read */
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if (offset + ret > dio->i_size &&
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!(dio->flags & IOMAP_DIO_WRITE))
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ret = dio->i_size - offset;
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}
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/*
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* Try again to invalidate clean pages which might have been cached by
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* non-direct readahead, or faulted in by get_user_pages() if the source
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* of the write was an mmap'ed region of the file we're writing. Either
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* one is a pretty crazy thing to do, so we don't support it 100%. If
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* this invalidation fails, tough, the write still worked...
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*
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* And this page cache invalidation has to be after ->end_io(), as some
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* filesystems convert unwritten extents to real allocations in
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* ->end_io() when necessary, otherwise a racing buffer read would cache
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* zeros from unwritten extents.
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*/
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if (!dio->error && dio->size && (dio->flags & IOMAP_DIO_WRITE))
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kiocb_invalidate_post_direct_write(iocb, dio->size);
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inode_dio_end(file_inode(iocb->ki_filp));
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if (ret > 0) {
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iocb->ki_pos += ret;
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/*
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* If this is a DSYNC write, make sure we push it to stable
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* storage now that we've written data.
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*/
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if (dio->flags & IOMAP_DIO_NEED_SYNC)
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ret = generic_write_sync(iocb, ret);
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if (ret > 0)
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ret += dio->done_before;
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}
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trace_iomap_dio_complete(iocb, dio->error, ret);
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kfree(dio);
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return ret;
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}
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EXPORT_SYMBOL_GPL(iomap_dio_complete);
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static ssize_t iomap_dio_deferred_complete(void *data)
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{
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return iomap_dio_complete(data);
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}
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static void iomap_dio_complete_work(struct work_struct *work)
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{
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struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
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struct kiocb *iocb = dio->iocb;
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iocb->ki_complete(iocb, iomap_dio_complete(dio));
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}
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/*
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* Set an error in the dio if none is set yet. We have to use cmpxchg
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* as the submission context and the completion context(s) can race to
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* update the error.
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*/
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static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
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{
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cmpxchg(&dio->error, 0, ret);
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}
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void iomap_dio_bio_end_io(struct bio *bio)
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{
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struct iomap_dio *dio = bio->bi_private;
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bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
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struct kiocb *iocb = dio->iocb;
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if (bio->bi_status)
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iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
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if (!atomic_dec_and_test(&dio->ref))
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goto release_bio;
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/*
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* Synchronous dio, task itself will handle any completion work
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* that needs after IO. All we need to do is wake the task.
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*/
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if (dio->wait_for_completion) {
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struct task_struct *waiter = dio->submit.waiter;
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WRITE_ONCE(dio->submit.waiter, NULL);
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blk_wake_io_task(waiter);
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goto release_bio;
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}
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/*
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* Flagged with IOMAP_DIO_INLINE_COMP, we can complete it inline
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*/
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if (dio->flags & IOMAP_DIO_INLINE_COMP) {
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WRITE_ONCE(iocb->private, NULL);
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iomap_dio_complete_work(&dio->aio.work);
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goto release_bio;
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}
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/*
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* If this dio is flagged with IOMAP_DIO_CALLER_COMP, then schedule
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* our completion that way to avoid an async punt to a workqueue.
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*/
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if (dio->flags & IOMAP_DIO_CALLER_COMP) {
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/* only polled IO cares about private cleared */
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iocb->private = dio;
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iocb->dio_complete = iomap_dio_deferred_complete;
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/*
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* Invoke ->ki_complete() directly. We've assigned our
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* dio_complete callback handler, and since the issuer set
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* IOCB_DIO_CALLER_COMP, we know their ki_complete handler will
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* notice ->dio_complete being set and will defer calling that
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* handler until it can be done from a safe task context.
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*
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* Note that the 'res' being passed in here is not important
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* for this case. The actual completion value of the request
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* will be gotten from dio_complete when that is run by the
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* issuer.
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*/
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iocb->ki_complete(iocb, 0);
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goto release_bio;
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}
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/*
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* Async DIO completion that requires filesystem level completion work
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* gets punted to a work queue to complete as the operation may require
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* more IO to be issued to finalise filesystem metadata changes or
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* guarantee data integrity.
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*/
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INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
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queue_work(file_inode(iocb->ki_filp)->i_sb->s_dio_done_wq,
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&dio->aio.work);
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release_bio:
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if (should_dirty) {
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bio_check_pages_dirty(bio);
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} else {
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bio_release_pages(bio, false);
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bio_put(bio);
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}
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}
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EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io);
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static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
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loff_t pos, unsigned len)
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{
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struct inode *inode = file_inode(dio->iocb->ki_filp);
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struct page *page = ZERO_PAGE(0);
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struct bio *bio;
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bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
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fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
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GFP_KERNEL);
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bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
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bio->bi_private = dio;
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bio->bi_end_io = iomap_dio_bio_end_io;
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__bio_add_page(bio, page, len, 0);
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iomap_dio_submit_bio(iter, dio, bio, pos);
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}
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/*
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* Figure out the bio's operation flags from the dio request, the
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* mapping, and whether or not we want FUA. Note that we can end up
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* clearing the WRITE_THROUGH flag in the dio request.
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*/
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static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
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const struct iomap *iomap, bool use_fua)
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{
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blk_opf_t opflags = REQ_SYNC | REQ_IDLE;
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if (!(dio->flags & IOMAP_DIO_WRITE))
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return REQ_OP_READ;
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opflags |= REQ_OP_WRITE;
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if (use_fua)
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opflags |= REQ_FUA;
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else
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dio->flags &= ~IOMAP_DIO_WRITE_THROUGH;
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return opflags;
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}
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static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
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struct iomap_dio *dio)
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{
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const struct iomap *iomap = &iter->iomap;
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struct inode *inode = iter->inode;
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unsigned int fs_block_size = i_blocksize(inode), pad;
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loff_t length = iomap_length(iter);
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loff_t pos = iter->pos;
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blk_opf_t bio_opf;
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struct bio *bio;
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bool need_zeroout = false;
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bool use_fua = false;
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int nr_pages, ret = 0;
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size_t copied = 0;
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size_t orig_count;
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if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
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!bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
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return -EINVAL;
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if (iomap->type == IOMAP_UNWRITTEN) {
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dio->flags |= IOMAP_DIO_UNWRITTEN;
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need_zeroout = true;
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}
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if (iomap->flags & IOMAP_F_SHARED)
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dio->flags |= IOMAP_DIO_COW;
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if (iomap->flags & IOMAP_F_NEW) {
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need_zeroout = true;
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} else if (iomap->type == IOMAP_MAPPED) {
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/*
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* Use a FUA write if we need datasync semantics, this is a pure
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* data IO that doesn't require any metadata updates (including
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* after IO completion such as unwritten extent conversion) and
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* the underlying device either supports FUA or doesn't have
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* a volatile write cache. This allows us to avoid cache flushes
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* on IO completion. If we can't use writethrough and need to
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* sync, disable in-task completions as dio completion will
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* need to call generic_write_sync() which will do a blocking
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* fsync / cache flush call.
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*/
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if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) &&
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(dio->flags & IOMAP_DIO_WRITE_THROUGH) &&
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(bdev_fua(iomap->bdev) || !bdev_write_cache(iomap->bdev)))
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use_fua = true;
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else if (dio->flags & IOMAP_DIO_NEED_SYNC)
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dio->flags &= ~IOMAP_DIO_CALLER_COMP;
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}
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/*
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* Save the original count and trim the iter to just the extent we
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* are operating on right now. The iter will be re-expanded once
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* we are done.
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*/
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orig_count = iov_iter_count(dio->submit.iter);
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iov_iter_truncate(dio->submit.iter, length);
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if (!iov_iter_count(dio->submit.iter))
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goto out;
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/*
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* We can only do deferred completion for pure overwrites that
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* don't require additional IO at completion. This rules out
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* writes that need zeroing or extent conversion, extend
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* the file size, or issue journal IO or cache flushes
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* during completion processing.
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*/
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if (need_zeroout ||
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((dio->flags & IOMAP_DIO_NEED_SYNC) && !use_fua) ||
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((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode)))
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dio->flags &= ~IOMAP_DIO_CALLER_COMP;
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/*
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* The rules for polled IO completions follow the guidelines as the
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* ones we set for inline and deferred completions. If none of those
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* are available for this IO, clear the polled flag.
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*/
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if (!(dio->flags & (IOMAP_DIO_INLINE_COMP|IOMAP_DIO_CALLER_COMP)))
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dio->iocb->ki_flags &= ~IOCB_HIPRI;
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if (need_zeroout) {
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/* zero out from the start of the block to the write offset */
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pad = pos & (fs_block_size - 1);
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if (pad)
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iomap_dio_zero(iter, dio, pos - pad, pad);
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}
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/*
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* Set the operation flags early so that bio_iov_iter_get_pages
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* can set up the page vector appropriately for a ZONE_APPEND
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* operation.
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*/
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bio_opf = iomap_dio_bio_opflags(dio, iomap, use_fua);
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nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS);
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do {
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size_t n;
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if (dio->error) {
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iov_iter_revert(dio->submit.iter, copied);
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copied = ret = 0;
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goto out;
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}
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bio = iomap_dio_alloc_bio(iter, dio, nr_pages, bio_opf);
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fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
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GFP_KERNEL);
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bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
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bio->bi_ioprio = dio->iocb->ki_ioprio;
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bio->bi_private = dio;
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bio->bi_end_io = iomap_dio_bio_end_io;
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ret = bio_iov_iter_get_pages(bio, dio->submit.iter);
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if (unlikely(ret)) {
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/*
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* We have to stop part way through an IO. We must fall
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* through to the sub-block tail zeroing here, otherwise
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* this short IO may expose stale data in the tail of
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* the block we haven't written data to.
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*/
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bio_put(bio);
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goto zero_tail;
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}
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n = bio->bi_iter.bi_size;
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if (dio->flags & IOMAP_DIO_WRITE) {
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task_io_account_write(n);
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} else {
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if (dio->flags & IOMAP_DIO_DIRTY)
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bio_set_pages_dirty(bio);
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}
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dio->size += n;
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copied += n;
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nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter,
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BIO_MAX_VECS);
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/*
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* We can only poll for single bio I/Os.
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*/
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if (nr_pages)
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dio->iocb->ki_flags &= ~IOCB_HIPRI;
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iomap_dio_submit_bio(iter, dio, bio, pos);
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pos += n;
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} while (nr_pages);
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/*
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* We need to zeroout the tail of a sub-block write if the extent type
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* requires zeroing or the write extends beyond EOF. If we don't zero
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* the block tail in the latter case, we can expose stale data via mmap
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* reads of the EOF block.
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*/
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zero_tail:
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if (need_zeroout ||
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((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
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/* zero out from the end of the write to the end of the block */
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pad = pos & (fs_block_size - 1);
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if (pad)
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iomap_dio_zero(iter, dio, pos, fs_block_size - pad);
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}
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out:
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/* Undo iter limitation to current extent */
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iov_iter_reexpand(dio->submit.iter, orig_count - copied);
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if (copied)
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return copied;
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return ret;
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}
|
|
|
|
static loff_t iomap_dio_hole_iter(const struct iomap_iter *iter,
|
|
struct iomap_dio *dio)
|
|
{
|
|
loff_t length = iov_iter_zero(iomap_length(iter), dio->submit.iter);
|
|
|
|
dio->size += length;
|
|
if (!length)
|
|
return -EFAULT;
|
|
return length;
|
|
}
|
|
|
|
static loff_t iomap_dio_inline_iter(const struct iomap_iter *iomi,
|
|
struct iomap_dio *dio)
|
|
{
|
|
const struct iomap *iomap = &iomi->iomap;
|
|
struct iov_iter *iter = dio->submit.iter;
|
|
void *inline_data = iomap_inline_data(iomap, iomi->pos);
|
|
loff_t length = iomap_length(iomi);
|
|
loff_t pos = iomi->pos;
|
|
size_t copied;
|
|
|
|
if (WARN_ON_ONCE(!iomap_inline_data_valid(iomap)))
|
|
return -EIO;
|
|
|
|
if (dio->flags & IOMAP_DIO_WRITE) {
|
|
loff_t size = iomi->inode->i_size;
|
|
|
|
if (pos > size)
|
|
memset(iomap_inline_data(iomap, size), 0, pos - size);
|
|
copied = copy_from_iter(inline_data, length, iter);
|
|
if (copied) {
|
|
if (pos + copied > size)
|
|
i_size_write(iomi->inode, pos + copied);
|
|
mark_inode_dirty(iomi->inode);
|
|
}
|
|
} else {
|
|
copied = copy_to_iter(inline_data, length, iter);
|
|
}
|
|
dio->size += copied;
|
|
if (!copied)
|
|
return -EFAULT;
|
|
return copied;
|
|
}
|
|
|
|
static loff_t iomap_dio_iter(const struct iomap_iter *iter,
|
|
struct iomap_dio *dio)
|
|
{
|
|
switch (iter->iomap.type) {
|
|
case IOMAP_HOLE:
|
|
if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
|
|
return -EIO;
|
|
return iomap_dio_hole_iter(iter, dio);
|
|
case IOMAP_UNWRITTEN:
|
|
if (!(dio->flags & IOMAP_DIO_WRITE))
|
|
return iomap_dio_hole_iter(iter, dio);
|
|
return iomap_dio_bio_iter(iter, dio);
|
|
case IOMAP_MAPPED:
|
|
return iomap_dio_bio_iter(iter, dio);
|
|
case IOMAP_INLINE:
|
|
return iomap_dio_inline_iter(iter, dio);
|
|
case IOMAP_DELALLOC:
|
|
/*
|
|
* DIO is not serialised against mmap() access at all, and so
|
|
* if the page_mkwrite occurs between the writeback and the
|
|
* iomap_iter() call in the DIO path, then it will see the
|
|
* DELALLOC block that the page-mkwrite allocated.
|
|
*/
|
|
pr_warn_ratelimited("Direct I/O collision with buffered writes! File: %pD4 Comm: %.20s\n",
|
|
dio->iocb->ki_filp, current->comm);
|
|
return -EIO;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
return -EIO;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
|
|
* is being issued as AIO or not. This allows us to optimise pure data writes
|
|
* to use REQ_FUA rather than requiring generic_write_sync() to issue a
|
|
* REQ_FLUSH post write. This is slightly tricky because a single request here
|
|
* can be mapped into multiple disjoint IOs and only a subset of the IOs issued
|
|
* may be pure data writes. In that case, we still need to do a full data sync
|
|
* completion.
|
|
*
|
|
* When page faults are disabled and @dio_flags includes IOMAP_DIO_PARTIAL,
|
|
* __iomap_dio_rw can return a partial result if it encounters a non-resident
|
|
* page in @iter after preparing a transfer. In that case, the non-resident
|
|
* pages can be faulted in and the request resumed with @done_before set to the
|
|
* number of bytes previously transferred. The request will then complete with
|
|
* the correct total number of bytes transferred; this is essential for
|
|
* completing partial requests asynchronously.
|
|
*
|
|
* Returns -ENOTBLK In case of a page invalidation invalidation failure for
|
|
* writes. The callers needs to fall back to buffered I/O in this case.
|
|
*/
|
|
struct iomap_dio *
|
|
__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
|
|
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
|
|
unsigned int dio_flags, void *private, size_t done_before)
|
|
{
|
|
struct inode *inode = file_inode(iocb->ki_filp);
|
|
struct iomap_iter iomi = {
|
|
.inode = inode,
|
|
.pos = iocb->ki_pos,
|
|
.len = iov_iter_count(iter),
|
|
.flags = IOMAP_DIRECT,
|
|
.private = private,
|
|
};
|
|
bool wait_for_completion =
|
|
is_sync_kiocb(iocb) || (dio_flags & IOMAP_DIO_FORCE_WAIT);
|
|
struct blk_plug plug;
|
|
struct iomap_dio *dio;
|
|
loff_t ret = 0;
|
|
|
|
trace_iomap_dio_rw_begin(iocb, iter, dio_flags, done_before);
|
|
|
|
if (!iomi.len)
|
|
return NULL;
|
|
|
|
dio = kmalloc(sizeof(*dio), GFP_KERNEL);
|
|
if (!dio)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
dio->iocb = iocb;
|
|
atomic_set(&dio->ref, 1);
|
|
dio->size = 0;
|
|
dio->i_size = i_size_read(inode);
|
|
dio->dops = dops;
|
|
dio->error = 0;
|
|
dio->flags = 0;
|
|
dio->done_before = done_before;
|
|
|
|
dio->submit.iter = iter;
|
|
dio->submit.waiter = current;
|
|
|
|
if (iocb->ki_flags & IOCB_NOWAIT)
|
|
iomi.flags |= IOMAP_NOWAIT;
|
|
|
|
if (iov_iter_rw(iter) == READ) {
|
|
/* reads can always complete inline */
|
|
dio->flags |= IOMAP_DIO_INLINE_COMP;
|
|
|
|
if (iomi.pos >= dio->i_size)
|
|
goto out_free_dio;
|
|
|
|
if (user_backed_iter(iter))
|
|
dio->flags |= IOMAP_DIO_DIRTY;
|
|
|
|
ret = kiocb_write_and_wait(iocb, iomi.len);
|
|
if (ret)
|
|
goto out_free_dio;
|
|
} else {
|
|
iomi.flags |= IOMAP_WRITE;
|
|
dio->flags |= IOMAP_DIO_WRITE;
|
|
|
|
/*
|
|
* Flag as supporting deferred completions, if the issuer
|
|
* groks it. This can avoid a workqueue punt for writes.
|
|
* We may later clear this flag if we need to do other IO
|
|
* as part of this IO completion.
|
|
*/
|
|
if (iocb->ki_flags & IOCB_DIO_CALLER_COMP)
|
|
dio->flags |= IOMAP_DIO_CALLER_COMP;
|
|
|
|
if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) {
|
|
ret = -EAGAIN;
|
|
if (iomi.pos >= dio->i_size ||
|
|
iomi.pos + iomi.len > dio->i_size)
|
|
goto out_free_dio;
|
|
iomi.flags |= IOMAP_OVERWRITE_ONLY;
|
|
}
|
|
|
|
/* for data sync or sync, we need sync completion processing */
|
|
if (iocb_is_dsync(iocb)) {
|
|
dio->flags |= IOMAP_DIO_NEED_SYNC;
|
|
|
|
/*
|
|
* For datasync only writes, we optimistically try using
|
|
* WRITE_THROUGH for this IO. This flag requires either
|
|
* FUA writes through the device's write cache, or a
|
|
* normal write to a device without a volatile write
|
|
* cache. For the former, Any non-FUA write that occurs
|
|
* will clear this flag, hence we know before completion
|
|
* whether a cache flush is necessary.
|
|
*/
|
|
if (!(iocb->ki_flags & IOCB_SYNC))
|
|
dio->flags |= IOMAP_DIO_WRITE_THROUGH;
|
|
}
|
|
|
|
/*
|
|
* Try to invalidate cache pages for the range we are writing.
|
|
* If this invalidation fails, let the caller fall back to
|
|
* buffered I/O.
|
|
*/
|
|
ret = kiocb_invalidate_pages(iocb, iomi.len);
|
|
if (ret) {
|
|
if (ret != -EAGAIN) {
|
|
trace_iomap_dio_invalidate_fail(inode, iomi.pos,
|
|
iomi.len);
|
|
ret = -ENOTBLK;
|
|
}
|
|
goto out_free_dio;
|
|
}
|
|
|
|
if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) {
|
|
ret = sb_init_dio_done_wq(inode->i_sb);
|
|
if (ret < 0)
|
|
goto out_free_dio;
|
|
}
|
|
}
|
|
|
|
inode_dio_begin(inode);
|
|
|
|
blk_start_plug(&plug);
|
|
while ((ret = iomap_iter(&iomi, ops)) > 0) {
|
|
iomi.processed = iomap_dio_iter(&iomi, dio);
|
|
|
|
/*
|
|
* We can only poll for single bio I/Os.
|
|
*/
|
|
iocb->ki_flags &= ~IOCB_HIPRI;
|
|
}
|
|
|
|
blk_finish_plug(&plug);
|
|
|
|
/*
|
|
* We only report that we've read data up to i_size.
|
|
* Revert iter to a state corresponding to that as some callers (such
|
|
* as the splice code) rely on it.
|
|
*/
|
|
if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size)
|
|
iov_iter_revert(iter, iomi.pos - dio->i_size);
|
|
|
|
if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) {
|
|
if (!(iocb->ki_flags & IOCB_NOWAIT))
|
|
wait_for_completion = true;
|
|
ret = 0;
|
|
}
|
|
|
|
/* magic error code to fall back to buffered I/O */
|
|
if (ret == -ENOTBLK) {
|
|
wait_for_completion = true;
|
|
ret = 0;
|
|
}
|
|
if (ret < 0)
|
|
iomap_dio_set_error(dio, ret);
|
|
|
|
/*
|
|
* If all the writes we issued were already written through to the
|
|
* media, we don't need to flush the cache on IO completion. Clear the
|
|
* sync flag for this case.
|
|
*/
|
|
if (dio->flags & IOMAP_DIO_WRITE_THROUGH)
|
|
dio->flags &= ~IOMAP_DIO_NEED_SYNC;
|
|
|
|
/*
|
|
* We are about to drop our additional submission reference, which
|
|
* might be the last reference to the dio. There are three different
|
|
* ways we can progress here:
|
|
*
|
|
* (a) If this is the last reference we will always complete and free
|
|
* the dio ourselves.
|
|
* (b) If this is not the last reference, and we serve an asynchronous
|
|
* iocb, we must never touch the dio after the decrement, the
|
|
* I/O completion handler will complete and free it.
|
|
* (c) If this is not the last reference, but we serve a synchronous
|
|
* iocb, the I/O completion handler will wake us up on the drop
|
|
* of the final reference, and we will complete and free it here
|
|
* after we got woken by the I/O completion handler.
|
|
*/
|
|
dio->wait_for_completion = wait_for_completion;
|
|
if (!atomic_dec_and_test(&dio->ref)) {
|
|
if (!wait_for_completion) {
|
|
trace_iomap_dio_rw_queued(inode, iomi.pos, iomi.len);
|
|
return ERR_PTR(-EIOCBQUEUED);
|
|
}
|
|
|
|
for (;;) {
|
|
set_current_state(TASK_UNINTERRUPTIBLE);
|
|
if (!READ_ONCE(dio->submit.waiter))
|
|
break;
|
|
|
|
blk_io_schedule();
|
|
}
|
|
__set_current_state(TASK_RUNNING);
|
|
}
|
|
|
|
return dio;
|
|
|
|
out_free_dio:
|
|
kfree(dio);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__iomap_dio_rw);
|
|
|
|
ssize_t
|
|
iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
|
|
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
|
|
unsigned int dio_flags, void *private, size_t done_before)
|
|
{
|
|
struct iomap_dio *dio;
|
|
|
|
dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags, private,
|
|
done_before);
|
|
if (IS_ERR_OR_NULL(dio))
|
|
return PTR_ERR_OR_ZERO(dio);
|
|
return iomap_dio_complete(dio);
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_dio_rw);
|