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Commit a4dff304 authored by Nicholas Bellinger's avatar Nicholas Bellinger
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target/file: Use O_DSYNC by default for FILEIO backends 



Convert to use O_DSYNC for all cases at FILEIO backend creation time to
avoid the extra syncing of pure timestamp updates with legacy O_SYNC during
default operation as recommended by hch.  Continue to do this independently of
Write Cache Enable (WCE) bit, as WCE=0 is currently the default for all backend
devices and enabled by user on per device basis via attrib/emulate_write_cache.

This patch drops the now unnecessary fd_buffered_io= token usage that was
originally signalling when to explictly disable O_SYNC at backend creation
time for buffered I/O operation.  This can end up being dangerous for a number
of reasons during physical node failure, so go ahead and drop this option
for now when O_DSYNC is used as the default.

Also allow explict FUA WRITEs -> vfs_fsync_range() call to function in
fd_execute_cmd() independently of WCE bit setting.

Reported-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 5f2a3d61

drivers/target/target_core_file.c

+17 −53
Original line number Original line Diff line number Diff line
@@ -133,16 +133,11 @@ static struct se_device *fd_create_virtdevice( 
		ret = PTR_ERR(dev_p);

		ret = PTR_ERR(dev_p);

		goto fail;

		goto fail;

	}

	}



	/* O_DIRECT too? */

	flags = O_RDWR | O_CREAT | O_LARGEFILE;



	/*

	/*

	 * If fd_buffered_io=1 has not been set explicitly (the default),

	 * Use O_DSYNC by default instead of O_SYNC to forgo syncing

	 * use O_SYNC to force FILEIO writes to disk.

	 * of pure timestamp updates.

	 */

	 */

	if (!(fd_dev->fbd_flags & FDBD_USE_BUFFERED_IO))

	flags = O_RDWR | O_CREAT | O_LARGEFILE | O_DSYNC;

		flags |= O_SYNC;





	file = filp_open(dev_p, flags, 0600);

	file = filp_open(dev_p, flags, 0600);

	if (IS_ERR(file)) {

	if (IS_ERR(file)) {
@@ -380,23 +375,6 @@ 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,

static int fd_execute_cmd(struct se_cmd *cmd, struct scatterlist *sgl,

		u32 sgl_nents, enum dma_data_direction data_direction)

		u32 sgl_nents, enum dma_data_direction data_direction)

{

{
@@ -411,19 +389,21 @@ static int fd_execute_cmd(struct se_cmd *cmd, struct scatterlist *sgl, 
		ret = fd_do_readv(cmd, sgl, sgl_nents);

		ret = fd_do_readv(cmd, sgl, sgl_nents);

	} else {

	} else {

		ret = fd_do_writev(cmd, sgl, sgl_nents);

		ret = fd_do_writev(cmd, sgl, sgl_nents);



		/*

		 * Perform implict vfs_fsync_range() for fd_do_writev() ops

		 * for SCSI WRITEs with Forced Unit Access (FUA) set.

		 * Allow this to happen independent of WCE=0 setting.

		 */

		if (ret > 0 &&

		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 &&

		    dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 &&

		    (cmd->se_cmd_flags & SCF_FUA)) {

		    (cmd->se_cmd_flags & SCF_FUA)) {

			/*

			struct fd_dev *fd_dev = dev->dev_ptr;

			 * We might need to be a bit smarter here

			loff_t start = cmd->t_task_lba *

			 * and return some sense data to let the initiator

				dev->se_sub_dev->se_dev_attrib.block_size;

			 * know the FUA WRITE cache sync failed..?

			loff_t end = start + cmd->data_length;

			 */

			fd_emulate_write_fua(cmd);

		}





			vfs_fsync_range(fd_dev->fd_file, start, end, 1);

		}

	}

	}





	if (ret < 0) {

	if (ret < 0) {
@@ -442,7 +422,6 @@ enum { 
static match_table_t tokens = {

static match_table_t tokens = {

	{Opt_fd_dev_name, "fd_dev_name=%s"},

	{Opt_fd_dev_name, "fd_dev_name=%s"},

	{Opt_fd_dev_size, "fd_dev_size=%s"},

	{Opt_fd_dev_size, "fd_dev_size=%s"},

	{Opt_fd_buffered_io, "fd_buffered_io=%d"},

	{Opt_err, NULL}

	{Opt_err, NULL}

};

};
@@ -454,7 +433,7 @@ static ssize_t fd_set_configfs_dev_params( 
	struct fd_dev *fd_dev = se_dev->se_dev_su_ptr;

	struct fd_dev *fd_dev = se_dev->se_dev_su_ptr;

	char *orig, *ptr, *arg_p, *opts;

	char *orig, *ptr, *arg_p, *opts;

	substring_t args[MAX_OPT_ARGS];

	substring_t args[MAX_OPT_ARGS];

	int ret = 0, arg, token;

	int ret = 0, token;





	opts = kstrdup(page, GFP_KERNEL);

	opts = kstrdup(page, GFP_KERNEL);

	if (!opts)

	if (!opts)
@@ -498,19 +477,6 @@ static ssize_t fd_set_configfs_dev_params( 
					" bytes\n", fd_dev->fd_dev_size);

					" bytes\n", fd_dev->fd_dev_size);

			fd_dev->fbd_flags |= FBDF_HAS_SIZE;

			fd_dev->fbd_flags |= FBDF_HAS_SIZE;

			break;

			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:

		default:

			break;

			break;

		}

		}
@@ -542,10 +508,8 @@ static ssize_t fd_show_configfs_dev_params( 
	ssize_t bl = 0;

	ssize_t bl = 0;





	bl = sprintf(b + bl, "TCM FILEIO ID: %u", fd_dev->fd_dev_id);

	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: O_DSYNC\n",

		fd_dev->fd_dev_name, fd_dev->fd_dev_size,

		fd_dev->fd_dev_name, fd_dev->fd_dev_size);

		(fd_dev->fbd_flags & FDBD_USE_BUFFERED_IO) ?

		"Buffered" : "Synchronous");

	return bl;

	return bl;

}

}

drivers/target/target_core_file.h

+0 −1
Original line number Original line Diff line number Diff line
@@ -14,7 +14,6 @@ 




#define FBDF_HAS_PATH		0x01

#define FBDF_HAS_PATH		0x01

#define FBDF_HAS_SIZE		0x02

#define FBDF_HAS_SIZE		0x02

#define FDBD_USE_BUFFERED_IO	0x04





struct fd_dev {

struct fd_dev {

	u32		fbd_flags;

	u32		fbd_flags;