[net-next-2.6.git] / fs / btrfs / export.c

#include <linux/fs.h>
#include <linux/types.h>
#include "ctree.h"
#include "disk-io.h"
#include "btrfs_inode.h"
#include "print-tree.h"
#include "export.h"
#include "compat.h"

#define BTRFS_FID_SIZE_NON_CONNECTABLE		(offsetof(struct btrfs_fid, parent_objectid)/4)
#define BTRFS_FID_SIZE_CONNECTABLE		(offsetof(struct btrfs_fid, parent_root_objectid)/4)
#define BTRFS_FID_SIZE_CONNECTABLE_ROOT		(sizeof(struct btrfs_fid)/4)

static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
			   int connectable)
{
	struct btrfs_fid *fid = (struct btrfs_fid *)fh;
	struct inode *inode = dentry->d_inode;
	int len = *max_len;
	int type;

	if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
	    (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
		return 255;

	len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
	type = FILEID_BTRFS_WITHOUT_PARENT;

	fid->objectid = BTRFS_I(inode)->location.objectid;
	fid->root_objectid = BTRFS_I(inode)->root->objectid;
	fid->gen = inode->i_generation;

	if (connectable && !S_ISDIR(inode->i_mode)) {
		struct inode *parent;
		u64 parent_root_id;

		spin_lock(&dentry->d_lock);

		parent = dentry->d_parent->d_inode;
		fid->parent_objectid = BTRFS_I(parent)->location.objectid;
		fid->parent_gen = parent->i_generation;
		parent_root_id = BTRFS_I(parent)->root->objectid;

		spin_unlock(&dentry->d_lock);

		if (parent_root_id != fid->root_objectid) {
			fid->parent_root_objectid = parent_root_id;
			len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
			type = FILEID_BTRFS_WITH_PARENT_ROOT;
		} else {
			len = BTRFS_FID_SIZE_CONNECTABLE;
			type = FILEID_BTRFS_WITH_PARENT;
		}
	}

	*max_len = len;
	return type;
}

static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
				       u64 root_objectid, u32 generation)
{
	struct btrfs_root *root;
	struct inode *inode;
	struct btrfs_key key;

	key.objectid = root_objectid;
	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
	key.offset = (u64)-1;

	root = btrfs_read_fs_root_no_name(btrfs_sb(sb)->fs_info, &key);
	if (IS_ERR(root))
		return ERR_CAST(root);

	key.objectid = objectid;
	btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
	key.offset = 0;

	inode = btrfs_iget(sb, &key, root, NULL);
	if (IS_ERR(inode))
		return (void *)inode;

	if (generation != inode->i_generation) {
		iput(inode);
		return ERR_PTR(-ESTALE);
	}

	return d_obtain_alias(inode);
}

static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
					 int fh_len, int fh_type)
{
	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
	u64 objectid, root_objectid;
	u32 generation;

	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
		if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
			return NULL;
		root_objectid = fid->root_objectid;
	} else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
		if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
			return NULL;
		root_objectid = fid->parent_root_objectid;
	} else
		return NULL;

	objectid = fid->parent_objectid;
	generation = fid->parent_gen;

	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
}

static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
					 int fh_len, int fh_type)
{
	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
	u64 objectid, root_objectid;
	u32 generation;

	if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
	     fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
	    (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
	     fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
	    (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
	     fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
		return NULL;

	objectid = fid->objectid;
	root_objectid = fid->root_objectid;
	generation = fid->gen;

	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
}

static struct dentry *btrfs_get_parent(struct dentry *child)
{
	struct inode *dir = child->d_inode;
	struct btrfs_root *root = BTRFS_I(dir)->root;
	struct btrfs_key key;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	int slot;
	u64 objectid;
	int ret;

	path = btrfs_alloc_path();

	key.objectid = dir->i_ino;
	btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
	key.offset = (u64)-1;

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0) {
		/* Error */
		btrfs_free_path(path);
		return ERR_PTR(ret);
	}
	leaf = path->nodes[0];
	slot = path->slots[0];
	if (ret) {
		/* btrfs_search_slot() returns the slot where we'd want to
		   insert a backref for parent inode #0xFFFFFFFFFFFFFFFF.
		   The _real_ backref, telling us what the parent inode
		   _actually_ is, will be in the slot _before_ the one
		   that btrfs_search_slot() returns. */
		if (!slot) {
			/* Unless there is _no_ key in the tree before... */
			btrfs_free_path(path);
			return ERR_PTR(-EIO);
		}
		slot--;
	}

	btrfs_item_key_to_cpu(leaf, &key, slot);
	btrfs_free_path(path);

	if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY)
		return ERR_PTR(-EINVAL);

	objectid = key.offset;

	/* If we are already at the root of a subvol, return the real root */
	if (objectid == dir->i_ino)
		return dget(dir->i_sb->s_root);

	/* Build a new key for the inode item */
	key.objectid = objectid;
	btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
	key.offset = 0;

	return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
}

const struct export_operations btrfs_export_ops = {
	.encode_fh	= btrfs_encode_fh,
	.fh_to_dentry	= btrfs_fh_to_dentry,
	.fh_to_parent	= btrfs_fh_to_parent,
	.get_parent	= btrfs_get_parent,
};
Commit	Line	Data
be6e8dc0 BR	1	#include <linux/fs.h>
	2	#include <linux/types.h>
	3	#include "ctree.h"
	4	#include "disk-io.h"
	5	#include "btrfs_inode.h"
	6	#include "print-tree.h"
	7	#include "export.h"
	8	#include "compat.h"
	9
be6e8dc0 BR	10	#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, parent_objectid)/4)
	11	#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, parent_root_objectid)/4)
	12	#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid)/4)
	13
	14	static int btrfs_encode_fh(struct dentry dentry, u32 fh, int *max_len,
	15	int connectable)
	16	{
	17	struct btrfs_fid fid = (struct btrfs_fid )fh;
	18	struct inode *inode = dentry->d_inode;
	19	int len = *max_len;
	20	int type;
	21
	22	if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) \|\|
	23	(connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
	24	return 255;
	25
	26	len = BTRFS_FID_SIZE_NON_CONNECTABLE;
	27	type = FILEID_BTRFS_WITHOUT_PARENT;
	28
	29	fid->objectid = BTRFS_I(inode)->location.objectid;
	30	fid->root_objectid = BTRFS_I(inode)->root->objectid;
	31	fid->gen = inode->i_generation;
	32
	33	if (connectable && !S_ISDIR(inode->i_mode)) {
	34	struct inode *parent;
	35	u64 parent_root_id;
	36
	37	spin_lock(&dentry->d_lock);
	38
	39	parent = dentry->d_parent->d_inode;
	40	fid->parent_objectid = BTRFS_I(parent)->location.objectid;
	41	fid->parent_gen = parent->i_generation;
	42	parent_root_id = BTRFS_I(parent)->root->objectid;
	43
	44	spin_unlock(&dentry->d_lock);
	45
	46	if (parent_root_id != fid->root_objectid) {
	47	fid->parent_root_objectid = parent_root_id;
	48	len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
	49	type = FILEID_BTRFS_WITH_PARENT_ROOT;
	50	} else {
	51	len = BTRFS_FID_SIZE_CONNECTABLE;
	52	type = FILEID_BTRFS_WITH_PARENT;
	53	}
	54	}
	55
	56	*max_len = len;
	57	return type;
	58	}
	59
	60	static struct dentry btrfs_get_dentry(struct super_block sb, u64 objectid,
	61	u64 root_objectid, u32 generation)
	62	{
	63	struct btrfs_root *root;
	64	struct inode *inode;
be6e8dc0 BR	65	struct btrfs_key key;
be6e8dc0 BR	66
2d4d9fbd DW	67	key.objectid = root_objectid;
	68	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
	69	key.offset = (u64)-1;
	70
	71	root = btrfs_read_fs_root_no_name(btrfs_sb(sb)->fs_info, &key);
	72	if (IS_ERR(root))
	73	return ERR_CAST(root);
	74
be6e8dc0 BR	75	key.objectid = objectid;
	76	btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
	77	key.offset = 0;
	78
be6e8dc0 BR	79	inode = btrfs_iget(sb, &key, root, NULL);
	80	if (IS_ERR(inode))
	81	return (void *)inode;
	82
	83	if (generation != inode->i_generation) {
	84	iput(inode);
	85	return ERR_PTR(-ESTALE);
	86	}
	87
50ec891c	88	return d_obtain_alias(inode);
be6e8dc0 BR	89	}
	90
	91	static struct dentry btrfs_fh_to_parent(struct super_block sb, struct fid *fh,
	92	int fh_len, int fh_type)
	93	{
	94	struct btrfs_fid fid = (struct btrfs_fid ) fh;
	95	u64 objectid, root_objectid;
	96	u32 generation;
	97
	98	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
	99	if (fh_len != BTRFS_FID_SIZE_CONNECTABLE)
	100	return NULL;
	101	root_objectid = fid->root_objectid;
	102	} else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
	103	if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
	104	return NULL;
	105	root_objectid = fid->parent_root_objectid;
	106	} else
	107	return NULL;
	108
	109	objectid = fid->parent_objectid;
	110	generation = fid->parent_gen;
	111
	112	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
	113	}
	114
	115	static struct dentry btrfs_fh_to_dentry(struct super_block sb, struct fid *fh,
	116	int fh_len, int fh_type)
	117	{
	118	struct btrfs_fid fid = (struct btrfs_fid ) fh;
	119	u64 objectid, root_objectid;
	120	u32 generation;
	121
	122	if ((fh_type != FILEID_BTRFS_WITH_PARENT \|\|
	123	fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
	124	(fh_type != FILEID_BTRFS_WITH_PARENT_ROOT \|\|
	125	fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
	126	(fh_type != FILEID_BTRFS_WITHOUT_PARENT \|\|
	127	fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
	128	return NULL;
	129
	130	objectid = fid->objectid;
	131	root_objectid = fid->root_objectid;
	132	generation = fid->gen;
	133
	134	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
	135	}
	136
	137	static struct dentry btrfs_get_parent(struct dentry child)
	138	{
	139	struct inode *dir = child->d_inode;
be6e8dc0 BR	140	struct btrfs_root *root = BTRFS_I(dir)->root;
	141	struct btrfs_key key;
	142	struct btrfs_path *path;
	143	struct extent_buffer *leaf;
be6e8dc0 BR	144	int slot;
	145	u64 objectid;
	146	int ret;
	147
	148	path = btrfs_alloc_path();
	149
	150	key.objectid = dir->i_ino;
	151	btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
87acb4ef	152	key.offset = (u64)-1;
be6e8dc0	153
87acb4ef	154	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
d54a8390 DW	155	if (ret < 0) {
	156	/* Error */
	157	btrfs_free_path(path);
	158	return ERR_PTR(ret);
	159	}
be6e8dc0 BR	160	leaf = path->nodes[0];
be6e8dc0 BR	161	slot = path->slots[0];
d54a8390 DW	162	if (ret) {
	163	/* btrfs_search_slot() returns the slot where we'd want to
	164	insert a backref for parent inode #0xFFFFFFFFFFFFFFFF.
	165	The _real_ backref, telling us what the parent inode
	166	_actually_ is, will be in the slot _before_ the one
	167	that btrfs_search_slot() returns. */
	168	if (!slot) {
	169	/* Unless there is _no_ key in the tree before... */
	170	btrfs_free_path(path);
	171	return ERR_PTR(-EIO);
	172	}
	173	slot--;
be6e8dc0 BR	174	}
be6e8dc0 BR	175
87acb4ef	176	btrfs_item_key_to_cpu(leaf, &key, slot);
be6e8dc0 BR	177	btrfs_free_path(path);
be6e8dc0 BR	178
be6e8dc0	179	if (key.objectid != dir->i_ino \|\| key.type != BTRFS_INODE_REF_KEY)
d54a8390	180	return ERR_PTR(-EINVAL);
be6e8dc0 BR	181
	182	objectid = key.offset;
	183
2d4d9fbd DW	184	/* If we are already at the root of a subvol, return the real root */
	185	if (objectid == dir->i_ino)
	186	return dget(dir->i_sb->s_root);
	187
be6e8dc0 BR	188	/* Build a new key for the inode item */
	189	key.objectid = objectid;
	190	btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
	191	key.offset = 0;
	192
50ec891c	193	return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
be6e8dc0 BR	194	}
	195
	196	const struct export_operations btrfs_export_ops = {
	197	.encode_fh = btrfs_encode_fh,
	198	.fh_to_dentry = btrfs_fh_to_dentry,
	199	.fh_to_parent = btrfs_fh_to_parent,
	200	.get_parent = btrfs_get_parent,
	201	};