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Message-Id: <1338422263-19874-1-git-send-email-nab@linux-iscsi.org>
Date: Wed, 30 May 2012 23:57:43 +0000
From: "Nicholas A. Bellinger" <nab@...ux-iscsi.org>
To: target-devel <target-devel@...r.kernel.org>
Cc: linux-scsi <linux-scsi@...r.kernel.org>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Nicholas Bellinger <nab@...ux-iscsi.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Christoph Hellwig <hch@....de>
Subject: [PATCH] target/file: Drop O_SYNC in favor of implict vfs_fsync_range for writes
From: Nicholas Bellinger <nab@...ux-iscsi.org>
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@...ux-foundation.org>
Cc: Christoph Hellwig <hch@....de>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
---
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
--
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