From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> This patch converts fd_execute_cmd() code to drop O_SYNC usage (the original default) in favor of always preforming an implict SCSI forced unit access (FUA) operation using vfs_fsync_range() based on LBA + SectorCount after each completed FILEIO backend write. This conversion was inspired by Linus's thoughts on O_SYNC usage in the thread: http://www.spinics.net/lists/linux-fsdevel/msg55681.html "O_SYNC is the absolutely anti-thesis of that kind of "multiple levels of overlapping IO". Because it requires that the IO is _done_ by the time you start more, which is against the whole point." This patch also drops the now unnecessary fd_buffered_io= token usage at createvirtdev time. Tested with lio-core code using fio writeverify to local tcm_loop + FILEIO <-> scsi_debug backed LUNs. Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> --- drivers/target/target_core_file.c | 68 +++++++------------------------------ drivers/target/target_core_file.h | 1 - 2 files changed, 13 insertions(+), 56 deletions(-) diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c index 686dba1..334b01c 100644 --- a/drivers/target/target_core_file.c +++ b/drivers/target/target_core_file.c @@ -137,13 +137,6 @@ static struct se_device *fd_create_virtdevice( /* O_DIRECT too? */ flags = O_RDWR | O_CREAT | O_LARGEFILE; - /* - * If fd_buffered_io=1 has not been set explicitly (the default), - * use O_SYNC to force FILEIO writes to disk. - */ - if (!(fd_dev->fbd_flags & FDBD_USE_BUFFERED_IO)) - flags |= O_SYNC; - file = filp_open(dev_p, flags, 0600); if (IS_ERR(file)) { pr_err("filp_open(%s) failed\n", dev_p); @@ -380,23 +373,6 @@ static void fd_emulate_sync_cache(struct se_cmd *cmd) } } -static void fd_emulate_write_fua(struct se_cmd *cmd) -{ - struct se_device *dev = cmd->se_dev; - struct fd_dev *fd_dev = dev->dev_ptr; - loff_t start = cmd->t_task_lba * - dev->se_sub_dev->se_dev_attrib.block_size; - loff_t end = start + cmd->data_length; - int ret; - - pr_debug("FILEIO: FUA WRITE LBA: %llu, bytes: %u\n", - cmd->t_task_lba, cmd->data_length); - - ret = vfs_fsync_range(fd_dev->fd_file, start, end, 1); - if (ret != 0) - pr_err("FILEIO: vfs_fsync_range() failed: %d\n", ret); -} - static int fd_execute_cmd(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, enum dma_data_direction data_direction) { @@ -410,20 +386,18 @@ static int fd_execute_cmd(struct se_cmd *cmd, struct scatterlist *sgl, if (data_direction == DMA_FROM_DEVICE) { ret = fd_do_readv(cmd, sgl, sgl_nents); } else { - ret = fd_do_writev(cmd, sgl, sgl_nents); - - if (ret > 0 && - dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0 && - dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 && - (cmd->se_cmd_flags & SCF_FUA)) { - /* - * We might need to be a bit smarter here - * and return some sense data to let the initiator - * know the FUA WRITE cache sync failed..? - */ - fd_emulate_write_fua(cmd); - } + struct fd_dev *fd_dev = dev->dev_ptr; + loff_t start = cmd->t_task_lba * + dev->se_sub_dev->se_dev_attrib.block_size; + loff_t end = start + cmd->data_length; + ret = fd_do_writev(cmd, sgl, sgl_nents); + /* + * Perform implict vfs_fsync_range() for fd_do_writev() ops + * instead of having to use O_SYNC for struct file. + */ + if (ret > 0) + vfs_fsync_range(fd_dev->fd_file, start, end, 1); } if (ret < 0) { @@ -442,7 +416,6 @@ enum { 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_err, NULL} }; @@ -498,19 +471,6 @@ static ssize_t fd_set_configfs_dev_params( " bytes\n", fd_dev->fd_dev_size); fd_dev->fbd_flags |= FBDF_HAS_SIZE; break; - case Opt_fd_buffered_io: - match_int(args, &arg); - if (arg != 1) { - pr_err("bogus fd_buffered_io=%d value\n", arg); - ret = -EINVAL; - goto out; - } - - pr_debug("FILEIO: Using buffered I/O" - " operations for struct fd_dev\n"); - - fd_dev->fbd_flags |= FDBD_USE_BUFFERED_IO; - break; default: break; } @@ -542,10 +502,8 @@ static ssize_t fd_show_configfs_dev_params( 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", - fd_dev->fd_dev_name, fd_dev->fd_dev_size, - (fd_dev->fbd_flags & FDBD_USE_BUFFERED_IO) ? - "Buffered" : "Synchronous"); + bl += sprintf(b + bl, " File: %s Size: %llu Mode: fsync\n", + fd_dev->fd_dev_name, fd_dev->fd_dev_size); return bl; } diff --git a/drivers/target/target_core_file.h b/drivers/target/target_core_file.h index fbd59ef..70ce7fd 100644 --- a/drivers/target/target_core_file.h +++ b/drivers/target/target_core_file.h @@ -14,7 +14,6 @@ #define FBDF_HAS_PATH 0x01 #define FBDF_HAS_SIZE 0x02 -#define FDBD_USE_BUFFERED_IO 0x04 struct fd_dev { u32 fbd_flags; -- 1.7.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
