Fix race in mount -o loop
Retry acquiring a loop device if the setup failed with EBUSY.
Signed-Off-By: Matthias Koenig <[EMAIL PROTECTED]>
Index: util-linux-devel/mount/lomount.c
===================================================================
--- util-linux-devel.orig/mount/lomount.c
+++ util-linux-devel/mount/lomount.c
@@ -341,8 +341,17 @@ set_loop(const char *device, const char
}
if (ioctl(fd, LOOP_SET_FD, ffd) < 0) {
- perror("ioctl: LOOP_SET_FD");
- return 1;
+ close(fd);
+ close(ffd);
+ switch (errno) {
+ case EBUSY:
+ if (verbose)
+ perror("ioctl: LOOP_SET_FD");
+ return 2;
+ default:
+ perror("ioctl: LOOP_SET_FD");
+ return 1;
+ }
}
close (ffd);
Index: util-linux-devel/mount/mount.c
===================================================================
--- util-linux-devel.orig/mount/mount.c
+++ util-linux-devel/mount/mount.c
@@ -846,20 +846,39 @@ loop_check(const char **spec, const char
printf(_("mount: skipping the setup of a loop device\n"));
} else {
int loopro = (*flags & MS_RDONLY);
+ int res;
- if (!*loopdev || !**loopdev)
- *loopdev = find_unused_loop_device();
- if (!*loopdev)
- return EX_SYSERR; /* no more loop devices */
- if (verbose)
- printf(_("mount: going to use the loop device %s\n"), *loopdev);
- offset = opt_offset ? strtoull(opt_offset, NULL, 0) : 0;
- if (set_loop(*loopdev, *loopfile, offset,
- opt_encryption, pfd, &loopro)) {
+ do {
+ if (!*loopdev || !**loopdev)
+ *loopdev = find_unused_loop_device();
+ if (!*loopdev)
+ return EX_SYSERR; /* no more loop devices */
if (verbose)
- printf(_("mount: failed setting up loop device\n"));
- return EX_FAIL;
- }
+ printf(_("mount: going to use the loop device %s\n"), *loopdev);
+ offset = opt_offset ? strtoull(opt_offset, NULL, 0) : 0;
+ if (res = set_loop (*loopdev, *loopfile, offset,
+ opt_encryption, pfd, &loopro)) {
+ switch(res) {
+ case 2:
+ /* loop dev has been grabbed by some other process,
+ try again, if not given explicitly */
+ if (!opt_loopdev) {
+ if (verbose)
+ printf("mount: stolen loop=%s ...trying again\n", *loopdev);
+ free(*loopdev);
+ *loopdev = NULL;
+ continue;
+ }
+ printf("mount: stolen loop=%s\n", *loopdev);
+ return EX_FAIL;
+ default:
+ if (verbose)
+ printf(_("mount: failed setting up loop device\n"));
+ return EX_FAIL;
+ }
+ }
+ } while (!*loopdev);
+
if (verbose > 1)
printf(_("mount: setup loop device successfully\n"));
*spec = *loopdev;
-
To unsubscribe from this list: send the line "unsubscribe util-linux-ng" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
