On Tue, Jun 19, 2007 at 12:58:06PM +0200, Matthias Koenig wrote: > Hi, > > in addition to the race described recently > (http://article.gmane.org/gmane.linux.utilities.util-linux-ng/241), > there is also a race if you have concurring processes running > mount -o loop. Patch below. Good idea! We can also add the same logic to the losetup.c:main(). A few suggestions: > --- util-linux-devel.orig/mount/lomount.c > +++ util-linux-devel/mount/lomount.c > @@ -341,8 +341,15 @@ set_loop(const char *device, const char > } > > if (ioctl(fd, LOOP_SET_FD, ffd) < 0) { > - perror("ioctl: LOOP_SET_FD"); > - return 1; > + switch (errno) { > + case EBUSY: > + if (verbose) > + perror("ioctl: LOOP_SET_FD"); close (ffd); > + return 2; > + default: > + perror("ioctl: LOOP_SET_FD"); close (ffd); > + return 1; > + } > } > close (ffd); > --- util-linux-devel.orig/mount/mount.c > +++ util-linux-devel/mount/mount.c > @@ -846,20 +846,34 @@ loop_check(const char **spec, const char > + 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 (verbose) > + printf("mount: stolen loop=%s ...trying again\n", *loopdev); > + *loopdev = NULL; ^^^^^^^^^^^^^^ memory leak? free(*loopdev); *loopdev = NULL; > + continue; ^^^^^^^^ Please, don't use the find_unused_loop_device() if user explicitly define a device. if (!opt_loop) { if (verbose) printf("mount: stolen loop=%s ...trying again\n", *loopdev); continue; } return EX_FAIL; Because: mount foo.img /foo -o loop=/dev/loop0 Karel -- Karel Zak <kzak@xxxxxxxxxx> - To unsubscribe from this list: send the line "unsubscribe util-linux-ng" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
