Support atomic writes by submitting a single BIO with the REQ_ATOMIC set. It must be ensured that the atomic write adheres to its rules, like naturally aligned offset, so call blkdev_dio_invalid() -> blkdev_atomic_write_valid() [with renaming blkdev_dio_unaligned() to blkdev_dio_invalid()] for this purpose. The BIO submission path currently checks for atomic writes which are too large, so no need to check here.
In blkdev_direct_IO(), if the nr_pages exceeds BIO_MAX_VECS, then we cannot produce a single BIO, so error in this case. Finally set FMODE_CAN_ATOMIC_WRITE when the bdev can support atomic writes and the associated file flag is for O_DIRECT. Signed-off-by: John Garry <[email protected]> --- block/fops.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/block/fops.c b/block/fops.c index 376265935714..be36c9fbd500 100644 --- a/block/fops.c +++ b/block/fops.c @@ -34,9 +34,12 @@ static blk_opf_t dio_bio_write_op(struct kiocb *iocb) return opf; } -static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos, - struct iov_iter *iter) +static bool blkdev_dio_invalid(struct block_device *bdev, loff_t pos, + struct iov_iter *iter, bool is_atomic) { + if (is_atomic && !generic_atomic_write_valid(iter, pos)) + return true; + return pos & (bdev_logical_block_size(bdev) - 1) || !bdev_iter_is_aligned(bdev, iter); } @@ -72,6 +75,8 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT; bio.bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint; bio.bi_ioprio = iocb->ki_ioprio; + if (iocb->ki_flags & IOCB_ATOMIC) + bio.bi_opf |= REQ_ATOMIC; ret = bio_iov_iter_get_pages(&bio, iter); if (unlikely(ret)) @@ -343,6 +348,9 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, task_io_account_write(bio->bi_iter.bi_size); } + if (iocb->ki_flags & IOCB_ATOMIC) + bio->bi_opf |= REQ_ATOMIC; + if (iocb->ki_flags & IOCB_NOWAIT) bio->bi_opf |= REQ_NOWAIT; @@ -359,12 +367,13 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) { struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host); + bool is_atomic = iocb->ki_flags & IOCB_ATOMIC; unsigned int nr_pages; if (!iov_iter_count(iter)) return 0; - if (blkdev_dio_unaligned(bdev, iocb->ki_pos, iter)) + if (blkdev_dio_invalid(bdev, iocb->ki_pos, iter, is_atomic)) return -EINVAL; nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1); @@ -373,6 +382,8 @@ static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) return __blkdev_direct_IO_simple(iocb, iter, bdev, nr_pages); return __blkdev_direct_IO_async(iocb, iter, bdev, nr_pages); + } else if (is_atomic) { + return -EINVAL; } return __blkdev_direct_IO(iocb, iter, bdev, bio_max_segs(nr_pages)); } @@ -612,6 +623,9 @@ static int blkdev_open(struct inode *inode, struct file *filp) if (!bdev) return -ENXIO; + if (bdev_can_atomic_write(bdev) && filp->f_flags & O_DIRECT) + filp->f_mode |= FMODE_CAN_ATOMIC_WRITE; + ret = bdev_open(bdev, mode, filp->private_data, NULL, filp); if (ret) blkdev_put_no_open(bdev); -- 2.31.1
