[CRIU] [PATCH 2/4] mount: add support for external block devices

[Andrey Vagin]

From: Andrew Vagin <avagin at virtuozzo.com>

It works like enable-fs, in this case we allow to mount a specified block device.

Options:
dump:		--external mnt[MAJOR:MINOR]
restore:	--mnt-ext-map mnt[MAJOR:MINOR]:DEVPATH

https://jira.sw.ru/browse/PSBM-39381

Signed-off-by: Andrew Vagin <avagin at virtuozzo.com>
---
 criu/crtools.c    |  1 +
 criu/mount.c      | 11 +++++++++++
 criu/proc_parse.c | 10 ++++++++++
 3 files changed, 22 insertions(+)

diff --git a/criu/crtools.c b/criu/crtools.c
index 02a24e7..3598b1b 100644
--- a/criu/crtools.c
+++ b/criu/crtools.c
@@ -882,6 +882,7 @@ usage:
 "                        Formats of RES:\n"
 "                            tty[rdev:dev]\n"
 "                            file[mnt_id:inode]\n"
+"                            mnt[MAJOR/MINOR]\n"
 "  --inherit-fd fd[<num>]:<existing>\n"
 "                        Inherit file descriptors. This allows to treat file descriptor\n"
 "                        <num> as being already opened via <existing> one and instead of\n"
diff --git a/criu/mount.c b/criu/mount.c
index f57b10c..85eeeda 100644
--- a/criu/mount.c
+++ b/criu/mount.c
@@ -1818,6 +1818,8 @@ static struct fstype *__find_fstype_by_name(char *fst, bool force_auto)
 {
 	int i;
 
+	if (fst == (void *) FSTYPE__AUTO)
+		return &fstypes[1];
 	/*
 	 * This fn is required for two things.
 	 * 1st -- to check supported filesystems (as just mounting
@@ -2091,6 +2093,15 @@ static char *resolve_source(struct mount_info *mi)
 
 	if (mi->fstype->code == FSTYPE__AUTO) {
 		struct stat st;
+		char devstr[64];
+		struct ext_mount *key;
+
+		snprintf(devstr, sizeof(devstr), "mnt[%d/%d]",
+				kdev_major(mi->s_dev), kdev_minor(mi->s_dev));
+
+		key = ext_mount_lookup(devstr);
+		if (key)
+			return key->val;
 
 		if (!stat(mi->source, &st) && S_ISBLK(st.st_mode) &&
 		    major(st.st_rdev) == kdev_major(mi->s_dev) &&
diff --git a/criu/proc_parse.c b/criu/proc_parse.c
index 2dd8dc4..55f0f5e 100644
--- a/criu/proc_parse.c
+++ b/criu/proc_parse.c
@@ -1292,6 +1292,16 @@ static int parse_mountinfo_ent(char *str, struct mount_info *new, char **fsname)
 
 	new->fstype = find_fstype_by_name(*fsname);
 
+	if (new->fstype->code == FSTYPE__UNSUPPORTED) {
+		char devstr[64];
+
+		snprintf(devstr, sizeof(devstr), "mnt[%d/%d]",
+				kdev_major(new->s_dev),  kdev_minor(new->s_dev));
+
+		if (external_lookup_id(devstr))
+			new->fstype = find_fstype_by_name((void *)FSTYPE__AUTO);
+	}
+
 	new->options = xmalloc(strlen(opt) + 1);
 	if (!new->options)
 		goto err;
-- 
2.5.0