[pve-devel] [PATCH 2/2] Add patch to use /dev/loop-control

[Wolfgang Bumiller]

LXC iterates through the /dev directory trying to attach to
existing loop devices, meaning it only uses nodes that
already exist. This patch makes it /dev/loop-control to find
and allocate new ones on the fly.

Fixes #651
---
 .../0001-Use-dev-loop-control-if-it-exists.patch   | 59 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 2 files changed, 60 insertions(+)
 create mode 100644 debian/patches/0001-Use-dev-loop-control-if-it-exists.patch

diff --git a/debian/patches/0001-Use-dev-loop-control-if-it-exists.patch b/debian/patches/0001-Use-dev-loop-control-if-it-exists.patch
new file mode 100644
index 0000000..23732d8
--- /dev/null
+++ b/debian/patches/0001-Use-dev-loop-control-if-it-exists.patch
@@ -0,0 +1,59 @@
+From edd7414a642a52005ebcdd92d5d643b105bbe041 Mon Sep 17 00:00:00 2001
+From: Wolfgang Bumiller <w.bumiller at proxmox.com>
+Date: Fri, 3 Jul 2015 14:10:17 +0200
+Subject: [PATCH] Use /dev/loop-control if it exists
+
+Loop devices can be added on the fly when needed, they're
+not always created beforehand. The loop-control device can
+be used to find and allocate the next available number
+instead of going through the /dev directory contents (which
+is now only a fallback mechanism).
+
+Signed-off-by: Wolfgang Bumiller <w.bumiller at proxmox.com>
+---
+ src/lxc/bdev.c | 22 +++++++++++++++++++++-
+ 1 file changed, 21 insertions(+), 1 deletion(-)
+
+diff --git a/src/lxc/bdev.c b/src/lxc/bdev.c
+index 520652c..5540b49 100644
+--- a/src/lxc/bdev.c
++++ b/src/lxc/bdev.c
+@@ -1868,7 +1868,7 @@ static int loop_detect(const char *path)
+ 	return 0;
+ }
+ 
+-static int find_free_loopdev(int *retfd, char *namep)
++static int find_free_loopdev_no_control(int *retfd, char *namep)
+ {
+ 	struct dirent dirent, *direntp;
+ 	struct loop_info64 lo;
+@@ -1908,6 +1908,26 @@ static int find_free_loopdev(int *retfd, char *namep)
+ 	return 0;
+ }
+ 
++static int find_free_loopdev(int *retfd, char *namep)
++{
++	int rc, fd = -1;
++	int ctl = open("/dev/loop-control", O_RDWR);
++	if (ctl < 0)
++		return find_free_loopdev_no_control(retfd, namep);
++	rc = ioctl(ctl, LOOP_CTL_GET_FREE);
++	if (rc >= 0) {
++		snprintf(namep, 100, "/dev/loop%d", rc);
++		fd = open(namep, O_RDWR);
++	}
++	close(ctl);
++	if (fd == -1) {
++		ERROR("No loop device found");
++		return -1;
++	}
++	*retfd = fd;
++	return 0;
++}
++
+ static int loop_mount(struct bdev *bdev)
+ {
+ 	int lfd, ffd = -1, ret = -1;
+-- 
+2.1.4
+
diff --git a/debian/patches/series b/debian/patches/series
index 5c40332..d4cae20 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -6,3 +6,4 @@ do-dot-call-chown_mapped_root-on-etc-pve.patch
 use-var-lib-vz-as-default-dir.patch
 do-not-use-config-path-for-rootfs.patch
 run-lxcnetaddbr.patch
+0001-Use-dev-loop-control-if-it-exists.patch
-- 
2.1.4