If losetup --find is called with parameters matching to an existing loop device,
re-use this loop device instead of allocating new one.
If --force is used, fall back to the old behavior.
Signed-off-by: Stanislav Brabec <sbrabec@xxxxxxx>
---
sys-utils/losetup.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/sys-utils/losetup.c b/sys-utils/losetup.c
index 0a323a9..ef6f52b 100644
--- a/sys-utils/losetup.c
+++ b/sys-utils/losetup.c
@@ -682,6 +682,51 @@ int main(int argc, char **argv)
{
int hasdev = loopcxt_has_device(&lc);
+ if (!hasdev && !force) {
+ res = loopcxt_find_by_backing_file(&lc,
+ file, offset, sizelimit,
+ LOOPDEV_FL_OFFSET | LOOPDEV_FL_SIZELIMIT);
+ if (res < 0) {
+ loopcxt_deinit(&lc);
+ errx(EXIT_FAILURE, _("failed to inspect loop devices"));
+ }
+ if (res == 0) {
+ uint32_t lc_encrypt_type;
+
+ res = -1;
+
+ /* Once a loop is initialized RO, there is no
+ way to change its parameters. */
+ if (loopcxt_is_readonly(&lc) && !(lo_flags & LO_FLAGS_READ_ONLY)) {
+ loopcxt_deinit(&lc);
+ errx(EXIT_FAILURE, _("%s: overlapping read-only loop device exists; use --force to ignore"),
+ loopcxt_get_device(&lc));
+ }
+
+ /* This is no more supported, but check to be
+ * safe. */
+ if (loopcxt_get_encrypt_type(&lc, &lc_encrypt_type)) {
+ loopcxt_deinit(&lc);
+ errx(EXIT_FAILURE, _("%s: encryption check failed"),
+ loopcxt_get_device(&lc));
+ }
+ if (lc_encrypt_type != LO_CRYPT_NONE) {
+ loopcxt_deinit(&lc);
+ errx(EXIT_FAILURE, _("%s: encryption check failed"),
+ loopcxt_get_device(&lc));
+ }
+
+ res = 0;
+ /* We found a device to recycle. Do not check
+ * for conflict. If it is conflicting, then
+ * user was already warned in past. */
+ goto got_device;
+ }
+ loopcxt_deinit(&lc);
+ if (loopcxt_init(&lc, 0))
+ err(EXIT_FAILURE, _("failed to initialize loopcxt"));
+ }
+
if (hasdev && !is_loopdev(loopcxt_get_device(&lc)))
loopcxt_add_device(&lc);
do {
@@ -718,6 +763,7 @@ int main(int argc, char **argv)
break;
} while (hasdev == 0);
+ got_device:
if (res == 0) {
if (showdev)
printf("%s\n", loopcxt_get_device(&lc));
--
2.9.2
--
Best Regards / S pozdravem,
Stanislav Brabec
software developer
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