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authorLauri Kasanen <curaga@operamail.com>2010-04-14 19:31:26 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2010-04-14 19:31:26 (GMT)
commit375a8ef5ea38ea10134c125c75a12bbf9d5ba7bd (patch)
tree1bd21b3e2ed9e15f92e5d0bdb03b276cac6f7a74
parent0ecc11659285337c0430f1b7004eb3b2901a93d3 (diff)
downloadbusybox-375a8ef5ea38ea10134c125c75a12bbf9d5ba7bd.tar.gz
busybox-375a8ef5ea38ea10134c125c75a12bbf9d5ba7bd.tar.bz2
mount: add an optional capability to create new /dev/loopN as needed
Signed-off-by: Lauri Kasanen <curaga@operamail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--libbb/loop.c14
-rw-r--r--scripts/defconfig1
-rw-r--r--util-linux/Config.in12
3 files changed, 25 insertions, 2 deletions
diff --git a/libbb/loop.c b/libbb/loop.c
index abf05dc..204fcc9 100644
--- a/libbb/loop.c
+++ b/libbb/loop.c
@@ -104,14 +104,24 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse
/* Find a loop device. */
try = *device ? *device : dev;
- for (i = 0; rc; i++) {
+ for (i = 0; rc && i < 256; i++) {
sprintf(dev, LOOP_FORMAT, i);
- /* Ran out of block devices, return failure. */
+ IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
+ if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
+ && errno == ENOENT
+ && try == dev
+ ) {
+ /* Node doesn't exist, try to create it. */
+ if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
+ goto try_to_open;
+ }
+ /* Ran out of block devices, return failure. */
rc = -ENOENT;
break;
}
+ try_to_open:
/* Open the sucker and check its loopiness. */
dfd = open(try, mode);
if (dfd < 0 && errno == EROFS) {
diff --git a/scripts/defconfig b/scripts/defconfig
index d13f5b1..0a748fe 100644
--- a/scripts/defconfig
+++ b/scripts/defconfig
@@ -574,6 +574,7 @@ CONFIG_FEATURE_UMOUNT_ALL=y
# Common options for mount/umount
#
CONFIG_FEATURE_MOUNT_LOOP=y
+# CONFIG_FEATURE_MOUNT_LOOP_CREATE is not set
# CONFIG_FEATURE_MTAB_SUPPORT is not set
#
diff --git a/util-linux/Config.in b/util-linux/Config.in
index acd74a2..a59cc1d 100644
--- a/util-linux/Config.in
+++ b/util-linux/Config.in
@@ -901,6 +901,18 @@ config FEATURE_MOUNT_LOOP
specify an offset or cryptographic options to the loopback device.
(If you don't want umount to free the loop device, use "umount -D".)
+config FEATURE_MOUNT_LOOP_CREATE
+ bool "Create new loopback devices if needed"
+ default n
+ depends on FEATURE_MOUNT_LOOP
+ help
+ Linux kernels >= 2.6.24 support unlimited loopback devices. They are
+ allocated for use when trying to use a loop device. The loop device
+ must however exist.
+
+ This feature lets mount to try to create next /dev/loopN device
+ if it does not find a free one.
+
config FEATURE_MTAB_SUPPORT
bool "Support for the old /etc/mtab file"
default n