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Subject[70/85] nbd: correct disconnect behavior
3.2.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Clements <paul.clements@steeleye.com>

commit c378f70adbc1bbecd9e6db145019f14b2f688c7c upstream.

Currently, when a disconnect is requested by the user (via NBD_DISCONNECT
ioctl) the return from NBD_DO_IT is undefined (it is usually one of
several error codes). This means that nbd-client does not know if a
manual disconnect was performed or whether a network error occurred.
Because of this, nbd-client's persist mode (which tries to reconnect after
error, but not after manual disconnect) does not always work correctly.

This change fixes this by causing NBD_DO_IT to always return 0 if a user
requests a disconnect. This means that nbd-client can correctly either
persist the connection (if an error occurred) or disconnect (if the user
requested it).

Signed-off-by: Paul Clements <paul.clements@steeleye.com>
Acked-by: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2: adjust device pointer name]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/block/nbd.c | 7 ++++++-
include/linux/nbd.h | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -598,8 +598,10 @@ static int __nbd_ioctl(struct block_devi
if (!lo->sock)
return -EINVAL;

+ lo->disconnect = 1;
+
nbd_send_req(lo, &sreq);
- return 0;
+ return 0;
}

case NBD_CLEAR_SOCK: {
@@ -629,6 +631,7 @@ static int __nbd_ioctl(struct block_devi
lo->sock = SOCKET_I(inode);
if (max_part > 0)
bdev->bd_invalidated = 1;
+ lo->disconnect = 0; /* we're connected now */
return 0;
} else {
fput(file);
@@ -701,6 +704,8 @@ static int __nbd_ioctl(struct block_devi
set_capacity(lo->disk, 0);
if (max_part > 0)
ioctl_by_bdev(bdev, BLKRRPART, 0);
+ if (lo->disconnect) /* user requested, ignore socket errors */
+ return 0;
return lo->harderror;
}

--- a/include/linux/nbd.h
+++ b/include/linux/nbd.h
@@ -68,6 +68,7 @@ struct nbd_device {
u64 bytesize;
pid_t pid; /* pid of nbd-client, if attached */
int xmit_timeout;
+ int disconnect; /* a disconnect has been requested by user */
};

#endif


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