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nbd: add set flags ioctl 

Add a set-flags ioctl, allowing various option flags to be set on an nbd
device.  This allows the nbd-client to set the device flags (to enable
read-only mode, or enable discard support, etc.).

Flags are typically specified by the nbd-server.  During the negotiation
phase of the nbd connection, the server sends its flags to the client.
The client then uses NBD_SET_FLAGS to inform the kernel of the options.

Also included is a one-line fix to debug output for the set-timeout ioctl.

Signed-off-by: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Paul Clements 2012-10-04 17:16:15 -07:00 committed by Linus Torvalds
parent de74e00a96
commit 2f01250888
2 changed files with 12 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/block/nbd.c
View File

@ -78,6 +78,8 @@ static const char *ioctl_cmd_to_ascii(int cmd)
case NBD_SET_SOCK: return "set-sock";
case NBD_SET_BLKSIZE: return "set-blksize";
case NBD_SET_SIZE: return "set-size";
case NBD_SET_TIMEOUT: return "set-timeout";
case NBD_SET_FLAGS: return "set-flags";
case NBD_DO_IT: return "do-it";
case NBD_CLEAR_SOCK: return "clear-sock";
case NBD_CLEAR_QUE: return "clear-que";
@ -468,7 +470,7 @@ static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
nbd_cmd(req) = NBD_CMD_READ;
if (rq_data_dir(req) == WRITE) {
nbd_cmd(req) = NBD_CMD_WRITE;
if (nbd->flags & NBD_READ_ONLY) {
if (nbd->flags & NBD_FLAG_READ_ONLY) {
dev_err(disk_to_dev(nbd->disk),
"Write on read-only\n");
goto error_out;
@ -651,6 +653,10 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
nbd->xmit_timeout = arg * HZ;
return 0;
case NBD_SET_FLAGS:
nbd->flags = arg;
return 0;
case NBD_SET_SIZE_BLOCKS:
nbd->bytesize = ((u64) arg) * nbd->blksize;
bdev->bd_inode->i_size = nbd->bytesize;

9
include/linux/nbd.h
View File

@ -27,6 +27,7 @@
#define NBD_SET_SIZE_BLOCKS _IO( 0xab, 7 )
#define NBD_DISCONNECT _IO( 0xab, 8 )
#define NBD_SET_TIMEOUT _IO( 0xab, 9 )
#define NBD_SET_FLAGS _IO( 0xab, 10)
enum {
NBD_CMD_READ = 0,
@ -34,6 +35,10 @@ enum {
NBD_CMD_DISC = 2
};
/* values for flags field */
#define NBD_FLAG_HAS_FLAGS (1 << 0) /* nbd-server supports flags */
#define NBD_FLAG_READ_ONLY (1 << 1) /* device is read-only */
#define nbd_cmd(req) ((req)->cmd[0])
/* userspace doesn't need the nbd_device structure */
@ -42,10 +47,6 @@ enum {
#include <linux/wait.h>
#include <linux/mutex.h>
/* values for flags field */
#define NBD_READ_ONLY 0x0001
#define NBD_WRITE_NOCHK 0x0002
struct request;
struct nbd_device {