block: new direct I/O implementation
Similar to the simple fast path, but we now need a dio structure to track multiple-bio completions. It's basically a cut-down version of the new iomap-based direct I/O code for filesystems, but without all the logic to call into the filesystem for extent lookup or allocation, and without the complex I/O completion workqueue handler for AIO - instead we just use the FUA bit on the bios to ensure data is flushed to stable storage. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>hifive-unleashed-5.1
Christoph Hellwig
Jens Axboe
parent
78250c02d9
commit
542ff7bf18
166
fs/block_dev.c
166
fs/block_dev.c
|
|
@ -270,11 +270,161 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
|
|||
return ret;
|
||||
}
|
||||
|
||||
struct blkdev_dio {
|
||||
union {
|
||||
struct kiocb *iocb;
|
||||
struct task_struct *waiter;
|
||||
};
|
||||
size_t size;
|
||||
atomic_t ref;
|
||||
bool multi_bio : 1;
|
||||
bool should_dirty : 1;
|
||||
bool is_sync : 1;
|
||||
struct bio bio;
|
||||
};
|
||||
|
||||
static struct bio_set *blkdev_dio_pool __read_mostly;
|
||||
|
||||
static void blkdev_bio_end_io(struct bio *bio)
|
||||
{
|
||||
struct blkdev_dio *dio = bio->bi_private;
|
||||
bool should_dirty = dio->should_dirty;
|
||||
|
||||
if (dio->multi_bio && !atomic_dec_and_test(&dio->ref)) {
|
||||
if (bio->bi_error && !dio->bio.bi_error)
|
||||
dio->bio.bi_error = bio->bi_error;
|
||||
} else {
|
||||
if (!dio->is_sync) {
|
||||
struct kiocb *iocb = dio->iocb;
|
||||
ssize_t ret = dio->bio.bi_error;
|
||||
|
||||
if (likely(!ret)) {
|
||||
ret = dio->size;
|
||||
iocb->ki_pos += ret;
|
||||
}
|
||||
|
||||
dio->iocb->ki_complete(iocb, ret, 0);
|
||||
bio_put(&dio->bio);
|
||||
} else {
|
||||
struct task_struct *waiter = dio->waiter;
|
||||
|
||||
WRITE_ONCE(dio->waiter, NULL);
|
||||
wake_up_process(waiter);
|
||||
}
|
||||
}
|
||||
|
||||
if (should_dirty) {
|
||||
bio_check_pages_dirty(bio);
|
||||
} else {
|
||||
struct bio_vec *bvec;
|
||||
int i;
|
||||
|
||||
bio_for_each_segment_all(bvec, bio, i)
|
||||
put_page(bvec->bv_page);
|
||||
bio_put(bio);
|
||||
}
|
||||
}
|
||||
|
||||
static ssize_t
|
||||
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
|
||||
__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
|
||||
{
|
||||
struct file *file = iocb->ki_filp;
|
||||
struct inode *inode = bdev_file_inode(file);
|
||||
struct block_device *bdev = I_BDEV(inode);
|
||||
unsigned blkbits = blksize_bits(bdev_logical_block_size(bdev));
|
||||
struct blkdev_dio *dio;
|
||||
struct bio *bio;
|
||||
bool is_read = (iov_iter_rw(iter) == READ);
|
||||
loff_t pos = iocb->ki_pos;
|
||||
blk_qc_t qc = BLK_QC_T_NONE;
|
||||
int ret;
|
||||
|
||||
if ((pos | iov_iter_alignment(iter)) & ((1 << blkbits) - 1))
|
||||
return -EINVAL;
|
||||
|
||||
bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, blkdev_dio_pool);
|
||||
bio_get(bio); /* extra ref for the completion handler */
|
||||
|
||||
dio = container_of(bio, struct blkdev_dio, bio);
|
||||
dio->is_sync = is_sync_kiocb(iocb);
|
||||
if (dio->is_sync)
|
||||
dio->waiter = current;
|
||||
else
|
||||
dio->iocb = iocb;
|
||||
|
||||
dio->size = 0;
|
||||
dio->multi_bio = false;
|
||||
dio->should_dirty = is_read && (iter->type == ITER_IOVEC);
|
||||
|
||||
for (;;) {
|
||||
bio->bi_bdev = bdev;
|
||||
bio->bi_iter.bi_sector = pos >> blkbits;
|
||||
bio->bi_private = dio;
|
||||
bio->bi_end_io = blkdev_bio_end_io;
|
||||
|
||||
ret = bio_iov_iter_get_pages(bio, iter);
|
||||
if (unlikely(ret)) {
|
||||
bio->bi_error = ret;
|
||||
bio_endio(bio);
|
||||
break;
|
||||
}
|
||||
|
||||
if (is_read) {
|
||||
bio->bi_opf = REQ_OP_READ;
|
||||
if (dio->should_dirty)
|
||||
bio_set_pages_dirty(bio);
|
||||
} else {
|
||||
bio->bi_opf = dio_bio_write_op(iocb);
|
||||
task_io_account_write(bio->bi_iter.bi_size);
|
||||
}
|
||||
|
||||
dio->size += bio->bi_iter.bi_size;
|
||||
pos += bio->bi_iter.bi_size;
|
||||
|
||||
nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
|
||||
if (!nr_pages) {
|
||||
qc = submit_bio(bio);
|
||||
break;
|
||||
}
|
||||
|
||||
if (!dio->multi_bio) {
|
||||
dio->multi_bio = true;
|
||||
atomic_set(&dio->ref, 2);
|
||||
} else {
|
||||
atomic_inc(&dio->ref);
|
||||
}
|
||||
|
||||
submit_bio(bio);
|
||||
bio = bio_alloc(GFP_KERNEL, nr_pages);
|
||||
}
|
||||
|
||||
if (!dio->is_sync)
|
||||
return -EIOCBQUEUED;
|
||||
|
||||
for (;;) {
|
||||
set_current_state(TASK_UNINTERRUPTIBLE);
|
||||
if (!READ_ONCE(dio->waiter))
|
||||
break;
|
||||
|
||||
if (!(iocb->ki_flags & IOCB_HIPRI) ||
|
||||
!blk_mq_poll(bdev_get_queue(bdev), qc))
|
||||
io_schedule();
|
||||
}
|
||||
__set_current_state(TASK_RUNNING);
|
||||
|
||||
ret = dio->bio.bi_error;
|
||||
if (likely(!ret)) {
|
||||
ret = dio->size;
|
||||
iocb->ki_pos += ret;
|
||||
}
|
||||
|
||||
bio_put(&dio->bio);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static ssize_t
|
||||
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
|
||||
{
|
||||
int nr_pages;
|
||||
|
||||
nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1);
|
||||
|
|
@ -282,11 +432,19 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
|
|||
return 0;
|
||||
if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)
|
||||
return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
|
||||
return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter,
|
||||
blkdev_get_block, NULL, NULL,
|
||||
DIO_SKIP_DIO_COUNT);
|
||||
|
||||
return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES));
|
||||
}
|
||||
|
||||
static __init int blkdev_init(void)
|
||||
{
|
||||
blkdev_dio_pool = bioset_create(4, offsetof(struct blkdev_dio, bio));
|
||||
if (!blkdev_dio_pool)
|
||||
return -ENOMEM;
|
||||
return 0;
|
||||
}
|
||||
module_init(blkdev_init);
|
||||
|
||||
int __sync_blockdev(struct block_device *bdev, int wait)
|
||||
{
|
||||
if (!bdev)
|
||||
|
|
|
|||
Loading…
Reference in New Issue