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patch-libxl-allow-PHY-backend-for-files-allocate-loop-devi.patch
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patch-libxl-allow-PHY-backend-for-files-allocate-loop-devi.patch
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From 33e6990e85a399b0c4dd51bdc9cd17e66d313c6e Mon Sep 17 00:00:00 2001
From: Marek Marczykowski <[email protected]>
Date: Tue, 16 Apr 2013 22:20:25 +0200
Subject: [PATCH] libxl: allow PHY backend for files - allocate loop device
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Organization: Invisible Things Lab
Cc: Marek Marczykowski-Górecki <[email protected]>
This is implementation of /etc/xen/scripts/block behaviour, but without
calling the script, which should be much faster.
Changes in v2:
- call libxl__loopdev_cleanup only on device remove and only
if no scripts already was called
- fix FD leak
Change in v3:
- set loopdev info
Changes in v3:
- update for Xen 4.8
Signed-off-by: Marek Marczykowski <[email protected]>
Signed-off-by: Marek Marczykowski-Górecki <[email protected]>
---
tools/libxl/libxl.c | 13 +++-
tools/libxl/libxl_device.c | 10 ++++
tools/libxl/libxl_internal.h | 9 +++
tools/libxl/libxl_linux.c | 138 ++++++++++++++++++++++++++++++++++++++++++-
tools/libxl/libxl_netbsd.c | 11 ++++
5 files changed, 179 insertions(+), 2 deletions(-)
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 2d29ad2..e5672e5 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2132,7 +2132,18 @@ static void device_disk_add(libxl__egc *egc, uint32_t domid,
if (!disk->script &&
disk->backend_domid == LIBXL_TOOLSTACK_DOMID) {
int major, minor;
- if (!libxl__device_physdisk_major_minor(dev, &major, &minor))
+ char *node;
+
+ node = libxl__loopdev_setup(gc, dev);
+ if (!node) {
+ /* error already reported by libxl__setup_loopdev */
+ goto out;
+ }
+ if (node != dev) {
+ flexarray_append_pair(back, "physical-device-path", node);
+ }
+
+ if (!libxl__device_physdisk_major_minor(node, &major, &minor))
flexarray_append_pair(back, "physical-device",
GCSPRINTF("%x:%x", major, minor));
}
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index ba7d100..6b2517b 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -954,6 +954,7 @@ static void device_hotplug(libxl__egc *egc, libxl__ao_device *aodev)
STATE_AO_GC(aodev->ao);
libxl__async_exec_state *aes = &aodev->aes;
char *be_path = libxl__device_backend_path(gc, aodev->dev);
+ char *node;
char **args = NULL, **env = NULL;
int rc = 0;
int hotplug, nullfd = -1;
@@ -997,6 +998,15 @@ static void device_hotplug(libxl__egc *egc, libxl__ao_device *aodev)
switch (hotplug) {
case 0:
/* no hotplug script to execute */
+ if (!aodev->num_exec && aodev->action == LIBXL__DEVICE_ACTION_REMOVE) {
+ /* check if we have loop device allocated - if so, try to release it */
+ node = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/physical-device-path", be_path));
+ if (node) {
+ /* ignore errors: if device is already released - no problem, if
+ * EBUSY - can be shared */
+ libxl__loopdev_cleanup(gc, node);
+ }
+ }
LOG(DEBUG, "No hotplug script to execute");
goto out;
case 1:
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 9d17586..8634f71 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1070,6 +1070,15 @@ static inline void libxl__domaindeathcheck_stop(libxl__gc *gc,
*/
_hidden int libxl__try_phy_backend(mode_t st_mode);
+/*
+ * libxl__setup_loopdev - Setup loop device if needed.
+ *
+ * Return its path on success or NULL in case of failure. If no loop device is
+ * needed, return original filename.
+ */
+_hidden char *libxl__loopdev_setup(libxl__gc *gc, char *filename);
+
+_hidden void libxl__loopdev_cleanup(libxl__gc *gc, char *devname);
_hidden char *libxl__devid_to_localdev(libxl__gc *gc, int devid);
diff --git a/tools/libxl/libxl_linux.c b/tools/libxl/libxl_linux.c
index ea5d8c1..a0bf8d8 100644
--- a/tools/libxl/libxl_linux.c
+++ b/tools/libxl/libxl_linux.c
@@ -16,16 +16,152 @@
#include "libxl_osdeps.h" /* must come before any other headers */
#include "libxl_internal.h"
+#include <linux/loop.h>
int libxl__try_phy_backend(mode_t st_mode)
{
if (S_ISBLK(st_mode) || S_ISREG(st_mode)) {
return 1;
}
return 0;
}
+char *libxl__loopdev_setup(libxl__gc *gc, char *filename) {
+ struct stat st;
+ DIR *sysblock;
+ int dir_fd;
+ int control_fd = -1;
+ int loop_fd = -1;
+ int file_fd = -1;
+ int devnr;
+ struct dirent *d;
+ struct loop_info64 info;
+ char *loop_name = NULL;
+ char *ret = NULL;
+
+ if (stat(filename, &st) < 0) {
+ LOG(ERROR, "unable to stat %s", filename);
+ return NULL;
+ }
+
+ /* do not do anything if filename already is block device */
+ if (S_ISBLK(st.st_mode))
+ return filename;
+
+ /* first check if file has already loop device assigned according to
+ *
+ * losetup implementation readdir on /sys/block + stat on
+ * loop/backing_file is faster than open each loop dev
+ */
+ sysblock = opendir("/sys/block");
+ if (!sysblock) {
+ LOG(ERROR, "unable to open /sys/block");
+ return NULL;
+ }
+
+ dir_fd = dirfd(sysblock);
+
+ while ((d = readdir(sysblock))) {
+ char name[300];
+ struct stat buf;
+
+ if (strcmp(d->d_name, ".") == 0
+ || strcmp(d->d_name, "..") == 0
+ || strncmp(d->d_name, "loop", 4) != 0)
+ continue;
+ snprintf(name, sizeof(name), "%s/loop/backing_file", d->d_name);
+ if (fstatat(dir_fd, name, &buf, 0) == 0) {
+ snprintf(name, sizeof(name), "/dev/%s", d->d_name);
+ loop_fd = open(name, O_RDWR);
+ if (loop_fd < 0) {
+ LOG(ERROR, "unable to open %s", name);
+ goto out;
+ }
+ if (ioctl(loop_fd, LOOP_GET_STATUS64, &info) < 0) {
+ LOG(ERROR, "unable to get %s info: %s", name, strerror(errno));
+ goto out;
+ }
+ if (info.lo_inode == st.st_ino && info.lo_device == st.st_dev) {
+ /* found */
+ ret = libxl__strdup(gc, name);
+ goto out;
+ }
+ close(loop_fd);
+ loop_fd = -1;
+ }
+ }
+
+ /* not found, so allocate new one */
+ file_fd = open(filename, O_RDWR);
+ if (file_fd < 0) {
+ LOG(ERROR, "unable to open %s: %s", filename, strerror(errno));
+ goto out;
+ }
+
+ control_fd = open("/dev/loop-control", O_RDWR);
+ if (control_fd < 0) {
+ LOG(ERROR, "unable to open /dev/loop-control: %s", strerror(errno));
+ goto out;
+ }
+ devnr = ioctl(control_fd, LOOP_CTL_GET_FREE);
+ if (devnr < 0) {
+ LOG(ERROR, "unable to get free loop device: %s", strerror(errno));
+ goto out;
+ }
+ loop_name = libxl__sprintf(gc, "/dev/loop%d", devnr);
+ loop_fd = open(loop_name, O_RDWR);
+ if (loop_fd < 0) {
+ LOG(ERROR, "unable to open %s: %s", loop_name, strerror(errno));
+ goto out;
+ }
+ if (ioctl(loop_fd, LOOP_SET_FD, file_fd) < 0) {
+ LOG(ERROR, "unable to set loop backing store: %s", strerror(errno));
+ goto out;
+ }
+ memset(&info, 0, sizeof(info));
+ strncpy((char*)info.lo_file_name, filename, LO_NAME_SIZE);
+ info.lo_file_name[LO_NAME_SIZE-1] = 0;
+ if (ioctl(loop_fd, LOOP_SET_STATUS64, &info) < 0) {
+ LOG(ERROR, "unable to set loop info: %s", strerror(errno));
+ goto out;
+ }
+ ret = loop_name;
+
+out:
+ if (file_fd >= 0)
+ close(file_fd);
+ if (control_fd >= 0)
+ close(control_fd);
+ if (loop_fd >= 0)
+ close(loop_fd);
+ if (sysblock)
+ closedir(sysblock);
+
+ return ret;
+}
+
+void libxl__loopdev_cleanup(libxl__gc *gc, char *devname)
+{
+ int loop_fd;
+
+ loop_fd = open(devname, O_RDWR);
+ if (loop_fd < 0) {
+ LOG(ERROR, "unable to open device %s: %s", devname, strerror(errno));
+ goto out;
+ }
+
+ if (ioctl(loop_fd, LOOP_CLR_FD) < 0) {
+ LOG(ERROR, "unable to release device %s: %s", devname, strerror(errno));
+ goto out;
+ }
+
+out:
+ if (loop_fd >= 0)
+ close(loop_fd);
+}
+
+
char *libxl__devid_to_localdev(libxl__gc *gc, int devid)
{
return libxl__devid_to_vdev(gc, devid);
diff --git a/tools/libxl/libxl_netbsd.c b/tools/libxl/libxl_netbsd.c
index 898e160..1e71572 100644
--- a/tools/libxl/libxl_netbsd.c
+++ b/tools/libxl/libxl_netbsd.c
@@ -25,6 +25,17 @@ int libxl__try_phy_backend(mode_t st_mode)
return 0;
}
+char *libxl__loopdev_setup(libxl__gc *gc, char *filename)
+{
+ /* files supported natively */
+ return filename;
+}
+
+void libxl__loopdev_cleanup(libxl__gc *gc, char *devname)
+{
+ /* nothing to do */
+}
+
char *libxl__devid_to_localdev(libxl__gc *gc, int devid)
{
/* TODO */
--
1.8.3.1