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btrfs: extended inode refs
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This patch adds basic support for extended inode refs. This includes support
for link and unlink of the refs, which basically gets us support for rename
as well.

Inode creation does not need changing - extended refs are only added after
the ref array is full.

Signed-off-by: Mark Fasheh <[email protected]>
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Mark Fasheh authored and Chris Mason committed Oct 9, 2012
1 parent 5a1d784 commit f186373
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Showing 7 changed files with 710 additions and 79 deletions.
68 changes: 68 additions & 0 deletions fs/btrfs/backref.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1109,6 +1109,74 @@ static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
found_key);
}

int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
u64 start_off, struct btrfs_path *path,
struct btrfs_inode_extref **ret_extref,
u64 *found_off)
{
int ret, slot;
struct btrfs_key key;
struct btrfs_key found_key;
struct btrfs_inode_extref *extref;
struct extent_buffer *leaf;
unsigned long ptr;

key.objectid = inode_objectid;
btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
key.offset = start_off;

ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
return ret;

while (1) {
leaf = path->nodes[0];
slot = path->slots[0];
if (slot >= btrfs_header_nritems(leaf)) {
/*
* If the item at offset is not found,
* btrfs_search_slot will point us to the slot
* where it should be inserted. In our case
* that will be the slot directly before the
* next INODE_REF_KEY_V2 item. In the case
* that we're pointing to the last slot in a
* leaf, we must move one leaf over.
*/
ret = btrfs_next_leaf(root, path);
if (ret) {
if (ret >= 1)
ret = -ENOENT;
break;
}
continue;
}

btrfs_item_key_to_cpu(leaf, &found_key, slot);

/*
* Check that we're still looking at an extended ref key for
* this particular objectid. If we have different
* objectid or type then there are no more to be found
* in the tree and we can exit.
*/
ret = -ENOENT;
if (found_key.objectid != inode_objectid)
break;
if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
break;

ret = 0;
ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
extref = (struct btrfs_inode_extref *)ptr;
*ret_extref = extref;
if (found_off)
*found_off = found_key.offset;
break;
}

return ret;
}

/*
* this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
* of the path are separated by '/' and the path is guaranteed to be
Expand Down
5 changes: 5 additions & 0 deletions fs/btrfs/backref.h
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Original file line number Diff line number Diff line change
Expand Up @@ -70,4 +70,9 @@ struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
struct btrfs_path *path);
void free_ipath(struct inode_fs_paths *ipath);

int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
u64 start_off, struct btrfs_path *path,
struct btrfs_inode_extref **ret_extref,
u64 *found_off);

#endif
53 changes: 46 additions & 7 deletions fs/btrfs/ctree.h
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Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,13 @@ struct btrfs_ordered_sum;
*/
#define BTRFS_NAME_LEN 255

/*
* Theoretical limit is larger, but we keep this down to a sane
* value. That should limit greatly the possibility of collisions on
* inode ref items.
*/
#define BTRFS_LINK_MAX 65535U

/* 32 bytes in various csum fields */
#define BTRFS_CSUM_SIZE 32

Expand Down Expand Up @@ -489,14 +496,17 @@ struct btrfs_super_block {
*/
#define BTRFS_FEATURE_INCOMPAT_BIG_METADATA (1ULL << 5)

#define BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF (1ULL << 6)

#define BTRFS_FEATURE_COMPAT_SUPP 0ULL
#define BTRFS_FEATURE_COMPAT_RO_SUPP 0ULL
#define BTRFS_FEATURE_INCOMPAT_SUPP \
(BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF | \
BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL | \
BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS | \
BTRFS_FEATURE_INCOMPAT_BIG_METADATA | \
BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO)
BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO | \
BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)

/*
* A leaf is full of items. offset and size tell us where to find
Expand Down Expand Up @@ -643,6 +653,14 @@ struct btrfs_inode_ref {
/* name goes here */
} __attribute__ ((__packed__));

struct btrfs_inode_extref {
__le64 parent_objectid;
__le64 index;
__le16 name_len;
__u8 name[0];
/* name goes here */
} __attribute__ ((__packed__));

struct btrfs_timespec {
__le64 sec;
__le32 nsec;
Expand Down Expand Up @@ -1601,6 +1619,7 @@ struct btrfs_ioctl_defrag_range_args {
*/
#define BTRFS_INODE_ITEM_KEY 1
#define BTRFS_INODE_REF_KEY 12
#define BTRFS_INODE_EXTREF_KEY 13
#define BTRFS_XATTR_ITEM_KEY 24
#define BTRFS_ORPHAN_ITEM_KEY 48
/* reserve 2-15 close to the inode for later flexibility */
Expand Down Expand Up @@ -1987,6 +2006,13 @@ BTRFS_SETGET_STACK_FUNCS(block_group_flags,
BTRFS_SETGET_FUNCS(inode_ref_name_len, struct btrfs_inode_ref, name_len, 16);
BTRFS_SETGET_FUNCS(inode_ref_index, struct btrfs_inode_ref, index, 64);

/* struct btrfs_inode_extref */
BTRFS_SETGET_FUNCS(inode_extref_parent, struct btrfs_inode_extref,
parent_objectid, 64);
BTRFS_SETGET_FUNCS(inode_extref_name_len, struct btrfs_inode_extref,
name_len, 16);
BTRFS_SETGET_FUNCS(inode_extref_index, struct btrfs_inode_extref, index, 64);

/* struct btrfs_inode_item */
BTRFS_SETGET_FUNCS(inode_generation, struct btrfs_inode_item, generation, 64);
BTRFS_SETGET_FUNCS(inode_sequence, struct btrfs_inode_item, sequence, 64);
Expand Down Expand Up @@ -3184,19 +3210,32 @@ int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
const char *name, int name_len,
u64 inode_objectid, u64 ref_objectid, u64 *index);
struct btrfs_inode_ref *
btrfs_lookup_inode_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
const char *name, int name_len,
u64 inode_objectid, u64 ref_objectid, int mod);
int btrfs_get_inode_ref_index(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
const char *name, int name_len,
u64 inode_objectid, u64 ref_objectid, int mod,
u64 *ret_index);
int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, u64 objectid);
int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path,
struct btrfs_key *location, int mod);

struct btrfs_inode_extref *
btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
const char *name, int name_len,
u64 inode_objectid, u64 ref_objectid, int ins_len,
int cow);

int btrfs_find_name_in_ext_backref(struct btrfs_path *path,
u64 ref_objectid, const char *name,
int name_len,
struct btrfs_inode_extref **extref_ret);

/* file-item.c */
int btrfs_del_csums(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 bytenr, u64 len);
Expand Down
10 changes: 10 additions & 0 deletions fs/btrfs/hash.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,4 +24,14 @@ static inline u64 btrfs_name_hash(const char *name, int len)
{
return crc32c((u32)~1, name, len);
}

/*
* Figure the key offset of an extended inode ref
*/
static inline u64 btrfs_extref_hash(u64 parent_objectid, const char *name,
int len)
{
return (u64) crc32c(parent_objectid, name, len);
}

#endif
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