linux/drivers/target/target_core_file.h
Nicholas Bellinger b32f4c7ed8 target/file: Re-enable optional fd_buffered_io=1 operation
This patch re-adds the ability to optionally run in buffered FILEIO mode
(eg: w/o O_DSYNC) for device backends in order to once again use the
Linux buffered cache as a write-back storage mechanism.

This logic was originally dropped with mainline v3.5-rc commit:

commit a4dff3043c
Author: Nicholas Bellinger <nab@linux-iscsi.org>
Date:   Wed May 30 16:25:41 2012 -0700

    target/file: Use O_DSYNC by default for FILEIO backends

This difference with this patch is that fd_create_virtdevice() now
forces the explicit setting of emulate_write_cache=1 when buffered FILEIO
operation has been enabled.

(v2: Switch to FDBD_HAS_BUFFERED_IO_WCE + add more detailed
     comment as requested by hch)

Reported-by: Ferry <iscsitmp@bananateam.nl>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2012-10-02 13:15:21 -07:00

40 lines
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C

#ifndef TARGET_CORE_FILE_H
#define TARGET_CORE_FILE_H
#define FD_VERSION "4.0"
#define FD_MAX_DEV_NAME 256
#define FD_DEVICE_QUEUE_DEPTH 32
#define FD_MAX_DEVICE_QUEUE_DEPTH 128
#define FD_BLOCKSIZE 512
#define FD_MAX_SECTORS 1024
#define RRF_EMULATE_CDB 0x01
#define RRF_GOT_LBA 0x02
#define FBDF_HAS_PATH 0x01
#define FBDF_HAS_SIZE 0x02
#define FDBD_HAS_BUFFERED_IO_WCE 0x04
struct fd_dev {
u32 fbd_flags;
unsigned char fd_dev_name[FD_MAX_DEV_NAME];
/* Unique Ramdisk Device ID in Ramdisk HBA */
u32 fd_dev_id;
/* Number of SG tables in sg_table_array */
u32 fd_table_count;
u32 fd_queue_depth;
u32 fd_block_size;
unsigned long long fd_dev_size;
struct file *fd_file;
/* FILEIO HBA device is connected to */
struct fd_host *fd_host;
} ____cacheline_aligned;
struct fd_host {
u32 fd_host_dev_id_count;
/* Unique FILEIO Host ID */
u32 fd_host_id;
} ____cacheline_aligned;
#endif /* TARGET_CORE_FILE_H */