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<p>Acked-by: Maxim Patlasov <a class="moz-txt-link-rfc2396E"
href="mailto:mpatlasov@virtuozzo.com"><mpatlasov@virtuozzo.com></a></p>
<br>
<div class="moz-cite-prefix">On 07/13/2017 05:10 PM, Andrei Vagin
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1499991005-19199-1-git-send-email-avagin@openvz.org">
<pre wrap="">Currently we can get an image file for a ploop delta from sysfs, but
there is a problem, if a ploop was mounted or snapshoted from another
mount namespace. In this case, we can't report a full path to a delta in
a current mount namespace, because the origin namespace may be already
destroyed or a mount with ploop deltas can be mounted into another place
in the current mntns.
Here is an example of one of such cases:
$ unshare -m ploop mount /mnt/vstorage/test/DiskDescriptor.xml
Opening delta /mnt/vstorage/test/test
Opening delta /mnt/vstorage/test/test
Adding delta dev=/dev/ploop64360 img=/mnt/vstorage/test/test (rw)
$ cat /sys/block/ploop64360/pdelta/0/image
/test/test
$ cat /sys/block/ploop64360/pdelta/0/image_info
ino:254
sdev:0:38
$ stat /mnt/vstorage/test/test
Device: 26h/38d Inode: 254 Links: 1
The ploop tool uses delta names to find a proper device by
Diskdescriptor.xml. Actually, a path to a delta file isn't required in
this case, it is enough to know a pair of ino and s_dev.
This patch introduces one more file in sysfs, which is called image_info
and contains an inode number and a source devices for a delta file.
<a class="moz-txt-link-freetext" href="https://jira.sw.ru/browse/PSBM-68404">https://jira.sw.ru/browse/PSBM-68404</a>
Signed-off-by: Andrei Vagin <a class="moz-txt-link-rfc2396E" href="mailto:avagin@openvz.org"><avagin@openvz.org></a>
---
drivers/block/ploop/sysfs.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/drivers/block/ploop/sysfs.c b/drivers/block/ploop/sysfs.c
index 0395ccf..acd18ff 100644
--- a/drivers/block/ploop/sysfs.c
+++ b/drivers/block/ploop/sysfs.c
@@ -102,6 +102,22 @@ static ssize_t delta_image_show(struct ploop_delta *delta, char *page)
return len;
}
+static ssize_t delta_image_info_show(struct ploop_delta *delta, char *page)
+{
+ int len = -ENOENT;
+
+ mutex_lock(&delta->plo->sysfs_mutex);
+ if (delta->io.files.file) {
+ struct inode *inode = file_inode(delta->io.files.file);
+ len = snprintf(page, PAGE_SIZE, "ino:%lu\nsdev:%u:%u\n",
+ inode->i_ino,
+ MAJOR(inode->i_sb->s_dev),
+ MINOR(inode->i_sb->s_dev));
+ }
+ mutex_unlock(&delta->plo->sysfs_mutex);
+ return len;
+}
+
static ssize_t delta_format_show(struct ploop_delta *delta, char *page)
{
return delta_string_show(delta->ops->name, page);
@@ -147,6 +163,12 @@ static struct delta_sysfs_entry delta_image_entry = {
.store = NULL,
};
+static struct delta_sysfs_entry delta_image_info_entry = {
+ .attr = {.name = "image_info", .mode = S_IRUGO },
+ .show = delta_image_info_show,
+ .store = NULL,
+};
+
static struct delta_sysfs_entry delta_format_entry = {
.attr = {.name = "format", .mode = S_IRUGO },
.show = delta_format_show,
@@ -179,6 +201,7 @@ static struct delta_sysfs_entry delta_dump_entry = {
static struct attribute *default_attrs[] = {
&delta_level_entry.attr,
&delta_image_entry.attr,
+ &delta_image_info_entry.attr,
&delta_format_entry.attr,
&delta_io_entry.attr,
&delta_ro_entry.attr,
</pre>
</blockquote>
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