Add -f option to follow mounted subvolumes below the specified path, only
if it is the same filesystem.
[Example]
$ mkfs.btrfs -f $DEV
$ mkfs.btrfs -f $DEV2
$ mount $DEV /mnt
$ btrfs subvolume create /mnt/AAA
$ btrfs subvolume create /mnt/BBB
$ btrfs subvolume create /mnt/CCC
$ mkdir /mnt/AAA/bbb
$ mkdir /mnt/AAA/ccc
$ mkdir /mnt/AAA/other
$ umount /mnt
$ mount -o subvol=AAA $DEV /mnt
$ mount -o subvol=BBB $DEV /mnt/bbb
$ mount -o subvol=CCC $DEV /mnt/ccc
$ mount -o $DEV2 /mnt/other
$ btrfs subvolume list /mnt
ID 256 gen 9 top level 5 path .
$ btrfs subvolume list -f /mnt
ID 256 gen 9 top level 5 path .
ID 258 gen 7 top level 5 path bbb
ID 259 gen 8 top level 5 path ccc
Note that this option lists top-level subvolume if it is mounted in the
way.
Signed-off-by: Misono Tomohiro <misono.tomoh...@jp.fujitsu.com>
---
Documentation/btrfs-subvolume.asciidoc | 4 ++
cmds-subvolume.c | 116 +++++++++++++++++++++++++++++++--
2 files changed, 113 insertions(+), 7 deletions(-)
diff --git a/Documentation/btrfs-subvolume.asciidoc
b/Documentation/btrfs-subvolume.asciidoc
index fec4b769..b2461398 100644
--- a/Documentation/btrfs-subvolume.asciidoc
+++ b/Documentation/btrfs-subvolume.asciidoc
@@ -120,6 +120,10 @@ print only subvolumes below specified <path>.
-a::::
print all the subvolumes in the filesystem and distinguish between
absolute and relative path with respect to the given <path>.
+-f::::
+follow mounted subvolumes below <path> recursively and list them too
+(only if it is the same filesystem). If top-level subvolume is mounted
+in the way, it is also listed.
Field selection;;
-p::::
diff --git a/cmds-subvolume.c b/cmds-subvolume.c
index ea341d50..4ebe0377 100644
--- a/cmds-subvolume.c
+++ b/cmds-subvolume.c
@@ -28,6 +28,7 @@
#include <getopt.h>
#include <uuid/uuid.h>
#include <linux/magic.h>
+#include <mntent.h>
#include <btrfsutil.h>
@@ -1157,7 +1158,8 @@ static void get_subvols_info(struct subvol_list **subvols,
int fd,
int tree_id,
size_t *capacity,
- const char *prefix)
+ const char *prefix,
+ int show_top)
{
struct btrfs_util_subvolume_iterator *iter;
enum btrfs_util_error err;
@@ -1195,7 +1197,7 @@ static void get_subvols_info(struct subvol_list **subvols,
ret = -1;
goto out;
}
- if (id == BTRFS_FS_TREE_OBJECTID) {
+ if (!show_top && id == BTRFS_FS_TREE_OBJECTID) {
/* Skip top level subvolume */
ret = 0;
goto skip;
@@ -1280,6 +1282,7 @@ out:
static struct subvol_list *btrfs_list_subvols(int fd,
int is_list_all,
int absolute_path,
+ int follow_mount,
const char *path,
struct btrfs_list_filter_set_v2
*filter_set)
{
@@ -1295,7 +1298,8 @@ static struct subvol_list *btrfs_list_subvols(int fd,
if (is_list_all) {
get_subvols_info(&subvols, filter_set, fd,
- BTRFS_FS_TREE_OBJECTID, &capacity, NULL);
+ BTRFS_FS_TREE_OBJECTID, &capacity, NULL,
+ false);
} else {
char *fullpath;
@@ -1307,8 +1311,92 @@ static struct subvol_list *btrfs_list_subvols(int fd,
}
get_subvols_info(&subvols, filter_set, fd, 0, &capacity,
- (absolute_path ? fullpath : NULL));
+ (absolute_path ? fullpath : NULL), false);
+ if (subvols == NULL) {
+ free(fullpath);
+ return NULL;
+ }
+
+ /* Follow mounted subvolumes below @path */
+ if (follow_mount) {
+ struct mntent *mnt;
+ FILE *f;
+ DIR *dirstream;
+ u8 fsid[BTRFS_FSID_SIZE];
+ u8 fsid2[BTRFS_FSID_SIZE];
+ char *c;
+ int fd2;
+ int ret;
+
+ ret = get_fsid(path, fsid, 0);
+ if (ret < 0) {
+ error("failed to get fsid: %m");
+ free(fullpath);
+ free_subvol_list(subvols);
+ return NULL;
+ }
+
+ f = setmntent("/proc/self/mounts", "r");
+ if (f == NULL) {
+ error("failed to read mount entry: %m");
+ free(fullpath);
+ free_subvol_list(subvols);
+ return NULL;
+ }
+
+ /* Iterate for each mount entry */
+ while ((mnt = getmntent(f)) != NULL) {
+ if (strcmp(mnt->mnt_type, "btrfs"))
+ continue;
+
+ if (!strcmp(mnt->mnt_dir, fullpath))
+ continue;
+
+ c = strstr(mnt->mnt_dir, fullpath);
+ if (c != mnt->mnt_dir)
+ continue;
+
+ /* If fsid is different, skip it */
+ ret = get_fsid(mnt->mnt_dir, fsid2, 1);
+ if (ret < 0) {
+ /*
+ * ENOENT may happen when mount is
+ * stacked
+ */
+ if (errno == EACCES || errno == ENOENT)
+ continue;
+ error("failed to get fsid: %m");
+ free(fullpath);
+ free_subvol_list(subvols);
+ return NULL;
+ }
+ if (uuid_compare(fsid, fsid2))
+ continue;
+
+ fd2 = btrfs_open_dir(mnt->mnt_dir,
+ &dirstream, 1);
+ if (fd2 < 0) {
+ error("cannot open '%s': %m",
+ mnt->mnt_dir);
+ free(fullpath);
+ free_subvol_list(subvols);
+ return NULL;
+ }
+ get_subvols_info(&subvols, filter_set,
+ fd2, 0, &capacity,
+ (absolute_path ? mnt->mnt_dir :
+ (strlen(fullpath) == 1 ?
+ mnt->mnt_dir + 1 :
+ mnt->mnt_dir +
strlen(fullpath) + 1)),
+ true);
+ close_file_or_dir(fd2, dirstream);
+ if (subvols == NULL) {
+ free(fullpath);
+ return NULL;
+ }
+ }
+ }
free(fullpath);
}
@@ -1321,6 +1409,7 @@ static int btrfs_list_subvols_print_v2(int fd,
enum btrfs_list_layout layout,
int is_list_all,
int absolute_path,
+ int follow_mount,
const char *path,
const char *raw_prefix)
{
@@ -1330,7 +1419,7 @@ static int btrfs_list_subvols_print_v2(int fd,
subvols = btrfs_list_deleted_subvols(fd, filter_set);
else
subvols = btrfs_list_subvols(fd, is_list_all, absolute_path,
- path, filter_set);
+ follow_mount, path, filter_set);
if (!subvols)
return -1;
@@ -1454,6 +1543,8 @@ static const char * const cmd_subvol_list_usage[] = {
"-a print all the subvolumes in the filesystem and",
" distinguish absolute and relative path with respect",
" to the given <path> (require root privileges)",
+ "-f follow mounted subvolumes below the specified path",
+ " and list them too (only if it is the same filesystem)",
"",
"Field selection:",
"-p print parent ID",
@@ -1497,6 +1588,7 @@ static int cmd_subvol_list(int argc, char **argv)
int ret = -1, uerr = 0;
char *subvol;
int is_list_all = 0;
+ int follow_mount = 0;
int is_only_in_path = 0;
int absolute_path = 0;
DIR *dirstream = NULL;
@@ -1513,7 +1605,7 @@ static int cmd_subvol_list(int argc, char **argv)
};
c = getopt_long(argc, argv,
- "acdgopqsurARG:C:t", long_options, NULL);
+ "acdfgopqsurARG:C:t", long_options, NULL);
if (c < 0)
break;
@@ -1527,6 +1619,9 @@ static int cmd_subvol_list(int argc, char **argv)
case 'a':
is_list_all = 1;
break;
+ case 'f':
+ follow_mount = 1;
+ break;
case 'c':
btrfs_list_setup_print_column_v2(BTRFS_LIST_OGENERATION);
break;
@@ -1616,6 +1711,12 @@ static int cmd_subvol_list(int argc, char **argv)
goto out;
}
+ if (follow_mount && (is_list_all || is_only_in_path)) {
+ ret = -1;
+ error("cannot use -f with -a or -o option");
+ goto out;
+ }
+
subvol = argv[optind];
fd = btrfs_open_dir(subvol, &dirstream, 1);
if (fd < 0) {
@@ -1648,7 +1749,8 @@ static int cmd_subvol_list(int argc, char **argv)
btrfs_list_setup_print_column_v2(BTRFS_LIST_PATH);
ret = btrfs_list_subvols_print_v2(fd, filter_set, comparer_set,
- layout, is_list_all, absolute_path, subvol, NULL);
+ layout, is_list_all, absolute_path, follow_mount,
+ subvol, NULL);
out:
close_file_or_dir(fd, dirstream);
--
2.14.4
--
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