Patchwork [v4,1/3] Update ioctl order in nbd_init() to detect EBUSY

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Submitter Chunyan Liu
Date Dec. 2, 2011, 3:27 p.m.
Message ID <1322839676-7559-1-git-send-email-cyliu@suse.com>
Download mbox | patch
Permalink /patch/128889/
State New
Headers show

Comments

Chunyan Liu - Dec. 2, 2011, 3:27 p.m.
Update ioctl(s) in nbd_init() to detect device busy early.

Current nbd_init() issues NBD_CLEAR_SOCKET before NBD_SET_SOCKET, if issuing
"qemu-nbd -c /dev/nbd0 disk.img" twice, the second time won't detect EBUSY in
nbd_init(), but in nbd_client will report EBUSY and do clear socket (the 1st
time command will be affacted too because of no socket any more.)

No change to previous version.

Signed-off-by: Chunyan Liu <cyliu@suse.com>
---
 nbd.c |   27 +++++++++------------------
 1 files changed, 9 insertions(+), 18 deletions(-)

Patch

diff --git a/nbd.c b/nbd.c
index e6c931c..4184614 100644
--- a/nbd.c
+++ b/nbd.c
@@ -348,6 +348,15 @@  int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
 #ifdef __linux__
 int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
 {
+    TRACE("Setting NBD socket");
+
+    if (ioctl(fd, NBD_SET_SOCK, csock) == -1) {
+        int serrno = errno;
+        LOG("Failed to set NBD socket");
+        errno = serrno;
+        return -1;
+    }
+
     TRACE("Setting block size to %lu", (unsigned long)blocksize);
 
     if (ioctl(fd, NBD_SET_BLKSIZE, blocksize) == -1) {
@@ -386,24 +395,6 @@  int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
         return -1;
     }
 
-    TRACE("Clearing NBD socket");
-
-    if (ioctl(fd, NBD_CLEAR_SOCK) == -1) {
-        int serrno = errno;
-        LOG("Failed clearing NBD socket");
-        errno = serrno;
-        return -1;
-    }
-
-    TRACE("Setting NBD socket");
-
-    if (ioctl(fd, NBD_SET_SOCK, csock) == -1) {
-        int serrno = errno;
-        LOG("Failed to set NBD socket");
-        errno = serrno;
-        return -1;
-    }
-
     TRACE("Negotiation ended");
 
     return 0;