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mount: add an optional capability to create new /dev/loopN as needed

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Signed-off-by: Lauri Kasanen <curaga@operamail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Lauri Kasanen 2010-04-14 12:31:26 -07:00 committed by Denys Vlasenko
parent 0ecc116592
commit 375a8ef5ea
3 changed files with 25 additions and 2 deletions
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14
libbb/loop.c
View File

@ -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) {

1
scripts/defconfig
View File

@ -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
#

12
util-linux/Config.in
View File

@ -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