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Commit ac8e9819 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: add search and inode lookup ioctls 



The search ioctl is a generic tool for doing btree searches from
userland applications.  The first user of the search ioctl is a
subvolume listing feature, but we'll also use it to find new
files in a subvolume.

The search ioctl allows you to specify min and max keys to search for,
along with min and max transid.  It returns the items along with a
header that includes the item key.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 98d377a0

fs/btrfs/ioctl.c

+233 −16
Original line number Diff line number Diff line
@@ -744,16 +744,206 @@ static noinline int may_destroy_subvol(struct btrfs_root *root) 
	return ret;

}



static noinline int key_in_sk(struct btrfs_key *key,

			      struct btrfs_ioctl_search_key *sk)

{

	if (key->objectid < sk->min_objectid)

		return 0;

	if (key->offset < sk->min_offset)

		return 0;

	if (key->type < sk->min_type)

		return 0;

	if (key->objectid > sk->max_objectid)

		return 0;

	if (key->type > sk->max_type)

		return 0;

	if (key->offset > sk->max_offset)

		return 0;

	return 1;

}



static noinline int copy_to_sk(struct btrfs_root *root,

			       struct btrfs_path *path,

			       struct btrfs_key *key,

			       struct btrfs_ioctl_search_key *sk,

			       char *buf,

			       unsigned long *sk_offset,

			       int *num_found)

{

	u64 found_transid;

	struct extent_buffer *leaf;

	struct btrfs_ioctl_search_header sh;

	unsigned long item_off;

	unsigned long item_len;

	int nritems;

	int i;

	int slot;

	int found = 0;

	int ret = 0;



	leaf = path->nodes[0];

	slot = path->slots[0];

	nritems = btrfs_header_nritems(leaf);



	if (btrfs_header_generation(leaf) > sk->max_transid) {

		i = nritems;

		goto advance_key;

	}

	found_transid = btrfs_header_generation(leaf);



	for (i = slot; i < nritems; i++) {

		item_off = btrfs_item_ptr_offset(leaf, i);

		item_len = btrfs_item_size_nr(leaf, i);



		if (item_len > BTRFS_SEARCH_ARGS_BUFSIZE)

			item_len = 0;



		if (sizeof(sh) + item_len + *sk_offset >

		    BTRFS_SEARCH_ARGS_BUFSIZE) {

			ret = 1;

			goto overflow;

		}



		btrfs_item_key_to_cpu(leaf, key, i);

		if (!key_in_sk(key, sk))

			continue;



		sh.objectid = key->objectid;

		sh.offset = key->offset;

		sh.type = key->type;

		sh.len = item_len;

		sh.transid = found_transid;



		/* copy search result header */

		memcpy(buf + *sk_offset, &sh, sizeof(sh));

		*sk_offset += sizeof(sh);



		if (item_len) {

			char *p = buf + *sk_offset;

			/* copy the item */

			read_extent_buffer(leaf, p,

					   item_off, item_len);

			*sk_offset += item_len;

			found++;

		}



		if (*num_found >= sk->nr_items)

			break;

	}

advance_key:

	if (key->offset < (u64)-1)

		key->offset++;

	else if (key->type < (u64)-1)

		key->type++;

	else if (key->objectid < (u64)-1)

		key->objectid++;

	ret = 0;

overflow:

	*num_found += found;

	return ret;

}



static noinline int search_ioctl(struct inode *inode,

				 struct btrfs_ioctl_search_args *args)

{

	struct btrfs_root *root;

	struct btrfs_key key;

	struct btrfs_key max_key;

	struct btrfs_path *path;

	struct btrfs_ioctl_search_key *sk = &args->key;

	struct btrfs_fs_info *info = BTRFS_I(inode)->root->fs_info;

	int ret;

	int num_found = 0;

	unsigned long sk_offset = 0;



	path = btrfs_alloc_path();

	if (!path)

		return -ENOMEM;



	if (sk->tree_id == 0) {

		/* search the root of the inode that was passed */

		root = BTRFS_I(inode)->root;

	} else {

		key.objectid = sk->tree_id;

		key.type = BTRFS_ROOT_ITEM_KEY;

		key.offset = (u64)-1;

		root = btrfs_read_fs_root_no_name(info, &key);

		if (IS_ERR(root)) {

			printk(KERN_ERR "could not find root %llu\n",

			       sk->tree_id);

			btrfs_free_path(path);

			return -ENOENT;

		}

	}



	key.objectid = sk->min_objectid;

	key.type = sk->min_type;

	key.offset = sk->min_offset;



	max_key.objectid = sk->max_objectid;

	max_key.type = sk->max_type;

	max_key.offset = sk->max_offset;



	path->keep_locks = 1;



	while(1) {

		ret = btrfs_search_forward(root, &key, &max_key, path, 0,

					   sk->min_transid);

		if (ret != 0) {

			if (ret > 0)

				ret = 0;

			goto err;

		}

		ret = copy_to_sk(root, path, &key, sk, args->buf,

				 &sk_offset, &num_found);

		btrfs_release_path(root, path);

		if (ret || num_found >= sk->nr_items)

			break;



	}

	ret = 0;

err:

	sk->nr_items = num_found;

	btrfs_free_path(path);

	return ret;

}



static noinline int btrfs_ioctl_tree_search(struct file *file,

					   void __user *argp)

{

	 struct btrfs_ioctl_search_args *args;

	 struct inode *inode;

	 int ret;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	args = kmalloc(sizeof(*args), GFP_KERNEL);

	if (!args)

		return -ENOMEM;



	if (copy_from_user(args, argp, sizeof(*args))) {

		kfree(args);

		return -EFAULT;

	}

	inode = fdentry(file)->d_inode;

	ret = search_ioctl(inode, args);

	if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))

		ret = -EFAULT;

	kfree(args);

	return ret;

}



/*

  Search INODE_REFs to identify path name of 'dirid' directory

  in a 'tree_id' tree. and sets path name to 'name'.

 * Search INODE_REFs to identify path name of 'dirid' directory

 * in a 'tree_id' tree. and sets path name to 'name'.

 */

static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,

				u64 tree_id, u64 dirid, char *name)

{

	struct btrfs_root *root;

	struct btrfs_key key;

	char *name_stack, *ptr;

	char *ptr;

	int ret = -1;

	int slot;

	int len;
@@ -771,13 +961,7 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info, 
	if (!path)

		return -ENOMEM;



	name_stack = kzalloc(BTRFS_PATH_NAME_MAX+1, GFP_NOFS);

	if (!name_stack) {

		btrfs_free_path(path);

		return -ENOMEM;

	}



	ptr = &name_stack[BTRFS_PATH_NAME_MAX];

	ptr = &name[BTRFS_INO_LOOKUP_PATH_MAX];



	key.objectid = tree_id;

	key.type = BTRFS_ROOT_ITEM_KEY;
@@ -802,14 +986,16 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info, 
		btrfs_item_key_to_cpu(l, &key, slot);



		if (ret > 0 && (key.objectid != dirid ||

					key.type != BTRFS_INODE_REF_KEY))

				key.type != BTRFS_INODE_REF_KEY)) {

			ret = -ENOENT;

			goto out;

		}



		iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);

		len = btrfs_inode_ref_name_len(l, iref);

		ptr -= len + 1;

		total_len += len + 1;

		if (ptr < name_stack)

		if (ptr < name)

			goto out;



		*(ptr + len) = '/';
@@ -824,14 +1010,41 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info, 
		dirid = key.objectid;



	}

	if (ptr < name_stack)

	if (ptr < name)

		goto out;

	strncpy(name, ptr, total_len);

	memcpy(name, ptr, total_len);

	name[total_len]='\0';

	ret = 0;

out:

	btrfs_free_path(path);

	kfree(name_stack);

	return ret;

}



static noinline int btrfs_ioctl_ino_lookup(struct file *file,

					   void __user *argp)

{

	 struct btrfs_ioctl_ino_lookup_args *args;

	 struct inode *inode;

	 int ret;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	args = kmalloc(sizeof(*args), GFP_KERNEL);

	if (copy_from_user(args, argp, sizeof(*args))) {

		kfree(args);

		return -EFAULT;

	}

	inode = fdentry(file)->d_inode;



	ret = btrfs_search_path_in_tree(BTRFS_I(inode)->root->fs_info,

					args->treeid, args->objectid,

					args->name);



	if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))

		ret = -EFAULT;



	kfree(args);

	return ret;

}
@@ -1430,6 +1643,10 @@ long btrfs_ioctl(struct file *file, unsigned int 
		return btrfs_ioctl_trans_start(file);

	case BTRFS_IOC_TRANS_END:

		return btrfs_ioctl_trans_end(file);

	case BTRFS_IOC_TREE_SEARCH:

		return btrfs_ioctl_tree_search(file, argp);

	case BTRFS_IOC_INO_LOOKUP:

		return btrfs_ioctl_ino_lookup(file, argp);

	case BTRFS_IOC_SYNC:

		btrfs_sync_fs(file->f_dentry->d_sb, 1);

		return 0;

fs/btrfs/ioctl.h

+66 −0
Original line number Diff line number Diff line
@@ -30,6 +30,68 @@ struct btrfs_ioctl_vol_args { 
	char name[BTRFS_PATH_NAME_MAX + 1];

};



#define BTRFS_INO_LOOKUP_PATH_MAX 4080

struct btrfs_ioctl_ino_lookup_args {

	__u64 treeid;

	__u64 objectid;

	char name[BTRFS_INO_LOOKUP_PATH_MAX];

};



struct btrfs_ioctl_search_key {

	/* which root are we searching.  0 is the tree of tree roots */

	__u64 tree_id;



	/* keys returned will be >= min and <= max */

	__u64 min_objectid;

	__u64 max_objectid;



	/* keys returned will be >= min and <= max */

	__u64 min_offset;

	__u64 max_offset;



	/* max and min transids to search for */

	__u64 min_transid;

	__u64 max_transid;



	/* keys returned will be >= min and <= max */

	__u32 min_type;

	__u32 max_type;



	/*

	 * how many items did userland ask for, and how many are we

	 * returning

	 */

	__u32 nr_items;



	/* align to 64 bits */

	__u32 unused;



	/* some extra for later */

	__u64 unused1;

	__u64 unused2;

	__u64 unused3;

	__u64 unused4;

};



struct btrfs_ioctl_search_header {

	__u64 transid;

	__u64 objectid;

	__u64 offset;

	__u32 type;

	__u32 len;

};



#define BTRFS_SEARCH_ARGS_BUFSIZE (4096 - sizeof(struct btrfs_ioctl_search_key))

/*

 * the buf is an array of search headers where

 * each header is followed by the actual item

 * the type field is expanded to 32 bits for alignment

 */

struct btrfs_ioctl_search_args {

	struct btrfs_ioctl_search_key key;

	char buf[BTRFS_SEARCH_ARGS_BUFSIZE];

};



struct btrfs_ioctl_clone_range_args {

  __s64 src_fd;

  __u64 src_offset, src_length;
@@ -67,4 +129,8 @@ struct btrfs_ioctl_clone_range_args { 
				   struct btrfs_ioctl_vol_args)

#define BTRFS_IOC_SNAP_DESTROY _IOW(BTRFS_IOCTL_MAGIC, 15, \

				struct btrfs_ioctl_vol_args)

#define BTRFS_IOC_TREE_SEARCH _IOWR(BTRFS_IOCTL_MAGIC, 17, \

				   struct btrfs_ioctl_search_args)

#define BTRFS_IOC_INO_LOOKUP _IOWR(BTRFS_IOCTL_MAGIC, 18, \

				   struct btrfs_ioctl_ino_lookup_args)

#endif