bcachefs: new subvol ioctlsbcachefs_subvol_ioctls

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

3 files changed, 83 insertions, 13 deletions

diff --git a/fs/bcachefs/bcachefs_ioctl.h b/fs/bcachefs/bcachefs_ioctl.h
index 4b8fba754b1c..2d3a2f9ea123 100644
--- a/fs/bcachefs/bcachefs_ioctl.h
+++ b/fs/bcachefs/bcachefs_ioctl.h
@@ -85,6 +85,8 @@ struct bch_ioctl_incremental {
 
 #define BCH_IOCTL_FSCK_OFFLINE	_IOW(0xbc,	19,  struct bch_ioctl_fsck_offline)
 #define BCH_IOCTL_FSCK_ONLINE	_IOW(0xbc,	20,  struct bch_ioctl_fsck_online)
+#define BCH_IOCTL_SUBVOLUME_LIST _IOW(0xbc,	21,  struct bch_ioctl_subvolume_list)
+#define BCH_IOCTL_SUBVOLUME_PATH _IOW(0xbc,	22,  struct bch_ioctl_subvolume_path)
 
 /* ioctl below act on a particular file, not the filesystem as a whole: */
 
@@ -409,4 +411,21 @@ struct bch_ioctl_fsck_online {
 	__u64			opts;		/* string */
 };
 
+/*
+ * BCH_IOCTL_SUBVOLUME_LIST: List child subvolumes of current subvolume
+ */
+struct bch_ioctl_subvolume_list {
+	__u64			buflen;
+	__u64			buf[];
+};
+
+/*
+ * BCH_IOCTL_SUBVOLUME_PATH: Get path to a given subvolid
+ */
+struct bch_ioctl_subvolume_path {
+	__u64			subvolid;
+	__u64			buflen;
+	__u8			buf[];
+};
+
 #endif /* _BCACHEFS_IOCTL_H */
diff --git a/fs/bcachefs/fs-common.c b/fs/bcachefs/fs-common.c
index 7d1180036954..55ee914ddba0 100644
--- a/fs/bcachefs/fs-common.c
+++ b/fs/bcachefs/fs-common.c
@@ -557,9 +557,12 @@ static void memreverse(char *dst, const char *src, size_t len)
 
 static void memreverse_inplace(char *p1, size_t len)
 {
-	char *p2  = p1 + len;
-	while (p2 > p1)
-		swap(*p1++, *--p2);
+	char *p2 = p1 + len;
+	while (p2 > p1) {
+		--p2;
+		swap(*p1, *p2);
+		p1++;
+	}
 }
 
 int bch2_inum_to_path_trans(struct btree_trans *trans, subvol_inum inum, darray_char *path)
@@ -570,9 +573,11 @@ int bch2_inum_to_path_trans(struct btree_trans *trans, subvol_inum inum, darray_
 	darray_init(path);
 
 	while (true) {
-		ret = darray_push(path, '/');
-		if (ret)
-			goto err;
+		if (path->nr) {
+			ret = darray_push(path, '/');
+			if (ret)
+				goto err;
+		}
 
 		if (inum.subvol == BCACHEFS_ROOT_SUBVOL &&
 		    inum.inum	== BCACHEFS_ROOT_INO)
@@ -580,13 +585,10 @@ int bch2_inum_to_path_trans(struct btree_trans *trans, subvol_inum inum, darray_
 
 		struct bch_inode_unpacked inode_u;
 		ret = bch2_inode_find_by_inum_trans(trans, inum, &inode_u);
-		if (ret)
-			goto err;
-
-		if (!inode_u.bi_dir) {
+		if (!ret && !inode_u.bi_dir)
 			ret = -BCH_ERR_ENOENT_no_backpointer;
+		if (ret)
 			goto err;
-		}
 
 		u32 subvol = inode_u.bi_parent_subvol ?: inum.subvol;
 		u32 snapshot;
@@ -619,9 +621,9 @@ int bch2_inum_to_path_trans(struct btree_trans *trans, subvol_inum inum, darray_
 
 	ret = darray_push(path, '\0');
 err:
+	bch2_trans_iter_exit(trans, &iter);
 	if (ret)
 		darray_exit(path);
-	bch2_trans_iter_exit(trans, &iter);
 	return ret;
 }
 
@@ -629,6 +631,6 @@ int bch2_subvol_to_path_trans(struct btree_trans *trans, u32 subvol, darray_char
 {
 	struct bch_subvolume s;
 
-	return  bch2_subvolume_get(trans, subvol, true, 0, &s) ?:
+	return  bch2_subvolume_get(trans, subvol, false, 0, &s) ?:
 		bch2_inum_to_path_trans(trans, (subvol_inum) { subvol, le64_to_cpu(s.inode) }, path);
 }
diff --git a/fs/bcachefs/fs-ioctl.c b/fs/bcachefs/fs-ioctl.c
index 3dc8630ff9fe..3f90fad039da 100644
--- a/fs/bcachefs/fs-ioctl.c
+++ b/fs/bcachefs/fs-ioctl.c
@@ -476,6 +476,47 @@ err:
 	return ret;
 }
 
+static long bch2_ioctl_subvolume_list(struct bch_fs *c, struct file *file,
+				      struct bch_ioctl_subvolume_list __user *user_arg)
+{
+	struct bch_inode_info *inode = file_bch_inode(file);
+	struct bch_ioctl_subvolume_list arg;
+	DARRAY(u64) children = {};
+
+	int ret = copy_from_user_errcode(&arg, user_arg, sizeof(arg)) ?:
+		  bch2_trans_run(c,
+		  for_each_btree_key_upto(trans, iter, BTREE_ID_subvolume_children,
+					  POS(inode->ei_subvol, 0),
+					  POS(inode->ei_subvol, U64_MAX), 0, k, ({
+			darray_push(&children, k.k->p.offset);
+		}))) ?:
+		(children.nr > arg.buflen ? -ERANGE : 0) ?:
+		(arg.buflen = children.nr, 0) ?:
+		copy_to_user_errcode(user_arg, &arg, sizeof(arg)) ?:
+		copy_to_user_errcode(&user_arg->buf, children.data,
+				     sizeof(children.data[0]) * children.nr);
+
+	darray_exit(&children);
+	return ret;
+}
+
+static long bch2_ioctl_subvolume_path(struct bch_fs *c, struct file *file,
+				      struct bch_ioctl_subvolume_path __user *user_arg)
+{
+	struct bch_ioctl_subvolume_path arg;
+	darray_char path = {};
+
+	int ret = copy_from_user_errcode(&arg, user_arg, sizeof(arg)) ?:
+		  bch2_subvol_to_path_checked(c, file->f_path.mnt, arg.subvolid, &path);
+		  (path.nr > arg.buflen ? -ERANGE : 0) ?:
+		  (arg.buflen = path.nr, 0) ?:
+		  copy_to_user_errcode(user_arg, &arg, sizeof(arg)) ?:
+		  copy_to_user_errcode(&user_arg->buf, path.data, path.nr);
+
+	darray_exit(&path);
+	return ret;
+}
+
 long bch2_fs_file_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 {
 	struct bch_inode_info *inode = file_bch_inode(file);
@@ -535,6 +576,14 @@ long bch2_fs_file_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 		break;
 	}
 
+	case BCH_IOCTL_SUBVOLUME_LIST:
+		ret = bch2_ioctl_subvolume_list(c, file, (void __user *) arg);
+		break;
+
+	case BCH_IOCTL_SUBVOLUME_PATH:
+		ret = bch2_ioctl_subvolume_path(c, file, (void __user *) arg);
+		break;
+
 	default:
 		ret = bch2_fs_ioctl(c, cmd, (void __user *) arg);
 		break;