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-rw-r--r--src/basic/btrfs-util.c43
-rw-r--r--src/basic/btrfs-util.h1
2 files changed, 35 insertions, 9 deletions
diff --git a/src/basic/btrfs-util.c b/src/basic/btrfs-util.c
index 49528dbf01..074deeccda 100644
--- a/src/basic/btrfs-util.c
+++ b/src/basic/btrfs-util.c
@@ -352,6 +352,19 @@ int btrfs_subvol_get_id_fd(int fd, uint64_t *ret) {
return 0;
}
+int btrfs_subvol_get_id(int fd, const char *subvol, uint64_t *ret) {
+ _cleanup_close_ int subvol_fd = -1;
+
+ assert(fd >= 0);
+ assert(ret);
+
+ subvol_fd = openat(fd, subvol, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+ if (subvol_fd < 0)
+ return -errno;
+
+ return btrfs_subvol_get_id_fd(subvol_fd, ret);
+}
+
static bool btrfs_ioctl_search_args_inc(struct btrfs_ioctl_search_args *args) {
assert(args);
@@ -937,7 +950,7 @@ int btrfs_subvol_remove_fd(int fd, const char *subvolume, bool recursive) {
return subvol_remove_children(fd, subvolume, 0, recursive);
}
-static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolume, uint64_t subvol_id, BtrfsSnapshotFlags flags) {
+static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolume, uint64_t old_subvol_id, BtrfsSnapshotFlags flags) {
struct btrfs_ioctl_search_args args = {
.key.tree_id = BTRFS_ROOT_TREE_OBJECTID,
@@ -956,8 +969,9 @@ static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolum
.flags = flags & BTRFS_SNAPSHOT_READ_ONLY ? BTRFS_SUBVOL_RDONLY : 0,
.fd = old_fd,
};
- int r;
_cleanup_close_ int subvolume_fd = -1;
+ uint64_t new_subvol_id;
+ int r;
assert(old_fd >= 0);
assert(new_fd >= 0);
@@ -972,13 +986,17 @@ static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolum
if (!(flags & BTRFS_SNAPSHOT_RECURSIVE))
return 0;
- if (subvol_id == 0) {
- r = btrfs_subvol_get_id_fd(old_fd, &subvol_id);
+ if (old_subvol_id == 0) {
+ r = btrfs_subvol_get_id_fd(old_fd, &old_subvol_id);
if (r < 0)
return r;
}
- args.key.min_offset = args.key.max_offset = subvol_id;
+ r = btrfs_subvol_get_id(new_fd, vol_args.name, &new_subvol_id);
+ if (r < 0)
+ return r;
+
+ args.key.min_offset = args.key.max_offset = old_subvol_id;
while (btrfs_ioctl_search_args_compare(&args) <= 0) {
const struct btrfs_ioctl_search_header *sh;
@@ -1001,17 +1019,24 @@ static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolum
if (sh->type != BTRFS_ROOT_BACKREF_KEY)
continue;
- if (sh->offset != subvol_id)
+
+ /* Avoid finding the source subvolume a second
+ * time */
+ if (sh->offset != old_subvol_id)
continue;
- ref = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
+ /* Avoid running into loops if the new
+ * subvolume is below the old one. */
+ if (sh->objectid == new_subvol_id)
+ continue;
+ ref = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
p = strndup((char*) ref + sizeof(struct btrfs_root_ref), le64toh(ref->name_len));
if (!p)
return -ENOMEM;
zero(ino_args);
- ino_args.treeid = subvol_id;
+ ino_args.treeid = old_subvol_id;
ino_args.objectid = htole64(ref->dirid);
if (ioctl(old_fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0)
@@ -1056,7 +1081,7 @@ static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolum
}
/* When btrfs clones the subvolumes, child
- * subvolumes appear as directories. Remove
+ * subvolumes appear as empty directories. Remove
* them, so that we can create a new snapshot
* in their place */
if (unlinkat(new_child_fd, p, AT_REMOVEDIR) < 0) {
diff --git a/src/basic/btrfs-util.h b/src/basic/btrfs-util.h
index a7eb895c93..8632c3638c 100644
--- a/src/basic/btrfs-util.h
+++ b/src/basic/btrfs-util.h
@@ -61,6 +61,7 @@ int btrfs_subvol_snapshot(const char *old_path, const char *new_path, BtrfsSnaps
int btrfs_subvol_set_read_only_fd(int fd, bool b);
int btrfs_subvol_set_read_only(const char *path, bool b);
int btrfs_subvol_get_read_only_fd(int fd);
+int btrfs_subvol_get_id(int fd, const char *subvolume, uint64_t *ret);
int btrfs_subvol_get_id_fd(int fd, uint64_t *ret);
int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *info);
int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *quota);