From 769031c92c8b85bd886f7e064430b7b512c68728 Mon Sep 17 00:00:00 2001 From: Andrei Vagin Date: Wed, 21 Mar 2018 23:55:02 -0700 Subject: scsi: target: target/file: Add support of direct and async I/O There are two advantages: * Direct I/O allows to avoid the write-back cache, so it reduces affects to other processes in the system. * Async I/O allows to handle a few commands concurrently. DIO + AIO shows a better perfomance for random write operations: Mode: O_DSYNC Async: 1 $ ./fio --bs=4K --direct=1 --rw=randwrite --ioengine=libaio --iodepth=64 --name=/dev/sda --runtime=20 --numjobs=2 WRITE: bw=45.9MiB/s (48.1MB/s), 21.9MiB/s-23.0MiB/s (22.0MB/s-25.2MB/s), io=919MiB (963MB), run=20002-20020msec Mode: O_DSYNC Async: 0 $ ./fio --bs=4K --direct=1 --rw=randwrite --ioengine=libaio --iodepth=64 --name=/dev/sdb --runtime=20 --numjobs=2 WRITE: bw=1607KiB/s (1645kB/s), 802KiB/s-805KiB/s (821kB/s-824kB/s), io=31.8MiB (33.4MB), run=20280-20295msec Known issue: DIF (PI) emulation doesn't work when a target uses async I/O, because DIF metadata is saved in a separate file, and it is another non-trivial task how to synchronize writing in two files, so that a following read operation always returns a consisten metadata for a specified block. Cc: "Nicholas A. Bellinger" Cc: Christoph Hellwig Cc: Bryant G. Ly Tested-by: Bryant G. Ly Signed-off-by: Andrei Vagin Reviewed-by: Christoph Hellwig Reviewed-by: Bryant G. Ly Reviewed-by: Mike Christie Signed-off-by: Martin K. Petersen --- drivers/target/target_core_file.c | 137 ++++++++++++++++++++++++++++++++++---- 1 file changed, 123 insertions(+), 14 deletions(-) (limited to 'drivers/target/target_core_file.c') diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c index 9b2c0c773022..16751ae55d7b 100644 --- a/drivers/target/target_core_file.c +++ b/drivers/target/target_core_file.c @@ -250,6 +250,84 @@ static void fd_destroy_device(struct se_device *dev) } } +struct target_core_file_cmd { + unsigned long len; + struct se_cmd *cmd; + struct kiocb iocb; +}; + +static void cmd_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) +{ + struct target_core_file_cmd *cmd; + + cmd = container_of(iocb, struct target_core_file_cmd, iocb); + + if (ret != cmd->len) + target_complete_cmd(cmd->cmd, SAM_STAT_CHECK_CONDITION); + else + target_complete_cmd(cmd->cmd, SAM_STAT_GOOD); + + kfree(cmd); +} + +static sense_reason_t +fd_execute_rw_aio(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, + enum dma_data_direction data_direction) +{ + int is_write = !(data_direction == DMA_FROM_DEVICE); + struct se_device *dev = cmd->se_dev; + struct fd_dev *fd_dev = FD_DEV(dev); + struct file *file = fd_dev->fd_file; + struct target_core_file_cmd *aio_cmd; + struct iov_iter iter = {}; + struct scatterlist *sg; + struct bio_vec *bvec; + ssize_t len = 0; + int ret = 0, i; + + aio_cmd = kmalloc(sizeof(struct target_core_file_cmd), GFP_KERNEL); + if (!aio_cmd) + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; + + bvec = kcalloc(sgl_nents, sizeof(struct bio_vec), GFP_KERNEL); + if (!bvec) { + kfree(aio_cmd); + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; + } + + for_each_sg(sgl, sg, sgl_nents, i) { + bvec[i].bv_page = sg_page(sg); + bvec[i].bv_len = sg->length; + bvec[i].bv_offset = sg->offset; + + len += sg->length; + } + + iov_iter_bvec(&iter, ITER_BVEC | is_write, bvec, sgl_nents, len); + + aio_cmd->cmd = cmd; + aio_cmd->len = len; + aio_cmd->iocb.ki_pos = cmd->t_task_lba * dev->dev_attrib.block_size; + aio_cmd->iocb.ki_filp = file; + aio_cmd->iocb.ki_complete = cmd_rw_aio_complete; + aio_cmd->iocb.ki_flags = IOCB_DIRECT; + + if (is_write && (cmd->se_cmd_flags & SCF_FUA)) + aio_cmd->iocb.ki_flags |= IOCB_DSYNC; + + if (is_write) + ret = call_write_iter(file, &aio_cmd->iocb, &iter); + else + ret = call_read_iter(file, &aio_cmd->iocb, &iter); + + kfree(bvec); + + if (ret != -EIOCBQUEUED) + cmd_rw_aio_complete(&aio_cmd->iocb, ret, 0); + + return 0; +} + static int fd_do_rw(struct se_cmd *cmd, struct file *fd, u32 block_size, struct scatterlist *sgl, u32 sgl_nents, u32 data_length, int is_write) @@ -527,7 +605,7 @@ fd_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb) } static sense_reason_t -fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, +fd_execute_rw_buffered(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, enum dma_data_direction data_direction) { struct se_device *dev = cmd->se_dev; @@ -536,16 +614,6 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, struct file *pfile = fd_dev->fd_prot_file; sense_reason_t rc; int ret = 0; - /* - * We are currently limited by the number of iovecs (2048) per - * single vfs_[writev,readv] call. - */ - if (cmd->data_length > FD_MAX_BYTES) { - pr_err("FILEIO: Not able to process I/O of %u bytes due to" - "FD_MAX_BYTES: %u iovec count limitation\n", - cmd->data_length, FD_MAX_BYTES); - return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; - } /* * Call vectorized fileio functions to map struct scatterlist * physical memory addresses to struct iovec virtual memory. @@ -620,14 +688,39 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, return 0; } +static sense_reason_t +fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, + enum dma_data_direction data_direction) +{ + struct se_device *dev = cmd->se_dev; + struct fd_dev *fd_dev = FD_DEV(dev); + + /* + * We are currently limited by the number of iovecs (2048) per + * single vfs_[writev,readv] call. + */ + if (cmd->data_length > FD_MAX_BYTES) { + pr_err("FILEIO: Not able to process I/O of %u bytes due to" + "FD_MAX_BYTES: %u iovec count limitation\n", + cmd->data_length, FD_MAX_BYTES); + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; + } + + if (fd_dev->fbd_flags & FDBD_HAS_ASYNC_IO) + return fd_execute_rw_aio(cmd, sgl, sgl_nents, data_direction); + return fd_execute_rw_buffered(cmd, sgl, sgl_nents, data_direction); +} + enum { - Opt_fd_dev_name, Opt_fd_dev_size, Opt_fd_buffered_io, Opt_err + Opt_fd_dev_name, Opt_fd_dev_size, Opt_fd_buffered_io, + Opt_fd_async_io, Opt_err }; static match_table_t tokens = { {Opt_fd_dev_name, "fd_dev_name=%s"}, {Opt_fd_dev_size, "fd_dev_size=%s"}, {Opt_fd_buffered_io, "fd_buffered_io=%d"}, + {Opt_fd_async_io, "fd_async_io=%d"}, {Opt_err, NULL} }; @@ -693,6 +786,21 @@ static ssize_t fd_set_configfs_dev_params(struct se_device *dev, fd_dev->fbd_flags |= FDBD_HAS_BUFFERED_IO_WCE; break; + case Opt_fd_async_io: + ret = match_int(args, &arg); + if (ret) + goto out; + if (arg != 1) { + pr_err("bogus fd_async_io=%d value\n", arg); + ret = -EINVAL; + goto out; + } + + pr_debug("FILEIO: Using async I/O" + " operations for struct fd_dev\n"); + + fd_dev->fbd_flags |= FDBD_HAS_ASYNC_IO; + break; default: break; } @@ -709,10 +817,11 @@ static ssize_t fd_show_configfs_dev_params(struct se_device *dev, char *b) ssize_t bl = 0; bl = sprintf(b + bl, "TCM FILEIO ID: %u", fd_dev->fd_dev_id); - bl += sprintf(b + bl, " File: %s Size: %llu Mode: %s\n", + bl += sprintf(b + bl, " File: %s Size: %llu Mode: %s Async: %d\n", fd_dev->fd_dev_name, fd_dev->fd_dev_size, (fd_dev->fbd_flags & FDBD_HAS_BUFFERED_IO_WCE) ? - "Buffered-WCE" : "O_DSYNC"); + "Buffered-WCE" : "O_DSYNC", + !!(fd_dev->fbd_flags & FDBD_HAS_ASYNC_IO)); return bl; } -- cgit v1.2.3