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Tools: hv: vss: Skip freezing filesystems backed by loop

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Since a loop device is backed by a file, a backup will already result in
its parent filesystem being frozen. It's sufficient to just freeze the
parent filesystem, so we can skip the loop device.

This avoids a situation where a loop device and its parent filesystem are
both frozen and then thawed out of order. For example, if the loop device
is enumerated first, we would thaw it while its parent filesystem is still
frozen. The thaw operation fails and the loop device remains frozen.

Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: Vyronas Tsingaras <vyronas@vtsingaras.me>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alex Ng 2017-08-06 13:12:52 -07:00 committed by Greg Kroah-Hartman
parent 5f972797b1
commit ea81fdf098
1 changed files with 7 additions and 0 deletions
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7
tools/hv/hv_vss_daemon.c
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@ -21,6 +21,7 @@
#include <sys/types.h>
#include <sys/poll.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <mntent.h>
@ -30,6 +31,7 @@
#include <ctype.h>
#include <errno.h>
#include <linux/fs.h>
#include <linux/major.h>
#include <linux/hyperv.h>
#include <syslog.h>
#include <getopt.h>
@ -70,6 +72,7 @@ static int vss_operate(int operation)
char match[] = "/dev/";
FILE *mounts;
struct mntent *ent;
struct stat sb;
char errdir[1024] = {0};
unsigned int cmd;
int error = 0, root_seen = 0, save_errno = 0;
@ -92,6 +95,10 @@ static int vss_operate(int operation)
while ((ent = getmntent(mounts))) {
if (strncmp(ent->mnt_fsname, match, strlen(match)))
continue;
if (stat(ent->mnt_fsname, &sb) == -1)
continue;
if (S_ISBLK(sb.st_mode) && major(sb.st_rdev) == LOOP_MAJOR)
continue;
if (hasmntopt(ent, MNTOPT_RO) != NULL)
continue;
if (strcmp(ent->mnt_type, "vfat") == 0)