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fsnotify: open_handle -- Handle multiple mounts with same s_dev

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When inotify is laying on uovermounted fs we should walk over
all mountpoints with same s_dev to find openable path.

Note on restore the path is usually already allocated during
dump stage so get_mark_path won't call for open_handle(), in
turn on dump stage the positive return from open_handle()
will cause fsnotify engine to find openable path, thus there
is kind of double work to be optimized in future.

For example we got a container where systemd-udevd inside
opens inotify for /dev/X entry then overmount ./dev path
with slave option and in result irmap engine on predump
can't figure out where the inotify is sitting causing
migrtion to abort.

Signed-off-by: Cyrill Gorcunov <gorcunov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
This commit is contained in:
Cyrill Gorcunov 2017-08-04 17:20:00 +03:00 • committed by Andrei Vagin
parent d541bc797c
commit e6537f3d8d
1 changed files with 16 additions and 11 deletions
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27
criu/fsnotify.c
View file

@ -196,6 +196,7 @@ err:
static int open_handle(unsigned int s_dev, unsigned long i_ino,
FhEntry *f_handle)
{
struct mount_info *m;
int mntfd, fd = -1;
fh_t handle;
@ -204,19 +205,23 @@ static int open_handle(unsigned int s_dev, unsigned long i_ino,
pr_debug("Opening fhandle %x:%Lx...\n",
s_dev, (unsigned long long)handle.__handle[0]);
mntfd = open_mount(s_dev);
if (mntfd < 0) {
pr_err("Mount root for %#08x not found\n", s_dev);
goto out;
}
for (m = mntinfo; m; m = m->next) {
if (m->s_dev != s_dev || !mnt_is_dir(m))
continue;
fd = userns_call(open_by_handle, UNS_FDOUT, &handle, sizeof(handle), mntfd);
if (fd < 0) {
pr_perror("Can't open file handle for %#08x:%#016lx",
s_dev, i_ino);
}
mntfd = __open_mountpoint(m, -1);
if (mntfd < 0) {
pr_err("Can't open mount for s_dev %x, continue\n", s_dev);
continue;
}
close(mntfd);
fd = userns_call(open_by_handle, UNS_FDOUT, &handle, sizeof(handle), mntfd);
if (fd >= 0) {
close(mntfd);
goto out;
}
close(mntfd);
}
out:
return fd;
}