- 根目录:
- fs
- xfs
- xfs_attr_leaf.h
/*
* Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
* Copyright (c) 2013 Red Hat, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef __XFS_ATTR_LEAF_H__
#define __XFS_ATTR_LEAF_H__
/*
* Attribute storage layout, internal structure, access macros, etc.
*
* Attribute lists are structured around Btrees where all the data
* elements are in the leaf nodes. Attribute names are hashed into an int,
* then that int is used as the index into the Btree. Since the hashval
* of an attribute name may not be unique, we may have duplicate keys. The
* internal links in the Btree are logical block offsets into the file.
*/
struct attrlist;
struct attrlist_cursor_kern;
struct xfs_attr_list_context;
struct xfs_da_args;
struct xfs_da_state;
struct xfs_da_state_blk;
struct xfs_inode;
struct xfs_trans;
/*========================================================================
* Attribute structure when equal to XFS_LBSIZE(mp) bytes.
*========================================================================*/
/*
* This is the structure of the leaf nodes in the Btree.
*
* Struct leaf_entry's are packed from the top. Name/values grow from the
* bottom but are not packed. The freemap contains run-length-encoded entries
* for the free bytes after the leaf_entry's, but only the N largest such,
* smaller runs are dropped. When the freemap doesn't show enough space
* for an allocation, we compact the name/value area and try again. If we
* still don't have enough space, then we have to split the block. The
* name/value structs (both local and remote versions) must be 32bit aligned.
*
* Since we have duplicate hash keys, for each key that matches, compare
* the actual name string. The root and intermediate node search always
* takes the first-in-the-block key match found, so we should only have
* to work "forw"ard. If none matches, continue with the "forw"ard leaf
* nodes until the hash key changes or the attribute name is found.
*
* We store the fact that an attribute is a ROOT/USER/SECURE attribute in
* the leaf_entry. The namespaces are independent only because we also look
* at the namespace bit when we are looking for a matching attribute name.
*
* We also store an "incomplete" bit in the leaf_entry. It shows that an
* attribute is in the middle of being created and should not be shown to
* the user if we crash during the time that the bit is set. We clear the
* bit when we have finished setting up the attribute. We do this because
* we cannot create some large attributes inside a single transaction, and we
* need some indication that we weren't finished if we crash in the middle.
*/
#define XFS_ATTR_LEAF_MAPSIZE 3 /* how many freespace slots */
typedef struct xfs_attr_leaf_map { /* RLE map of free bytes */
__be16 base; /* base of free region */
__be16 size; /* length of free region */
} xfs_attr_leaf_map_t;
typedef struct xfs_attr_leaf_hdr { /* constant-structure header block */
xfs_da_blkinfo_t info; /* block type, links, etc. */
__be16 count; /* count of active leaf_entry's */
__be16 usedbytes; /* num bytes of names/values stored */
__be16 firstused; /* first used byte in name area */
__u8 holes; /* != 0 if blk needs compaction */
__u8 pad1;
xfs_attr_leaf_map_t freemap[XFS_ATTR_LEAF_MAPSIZE];
/* N largest free regions */
} xfs_attr_leaf_hdr_t;
typedef struct xfs_attr_leaf_entry { /* sorted on key, not name */
__be32 hashval; /* hash value of name */
__be16 nameidx; /* index into buffer of name/value */
__u8 flags; /* LOCAL/ROOT/SECURE/INCOMPLETE flag */
__u8 pad2; /* unused pad byte */
} xfs_attr_leaf_entry_t;
typedef struct xfs_attr_leaf_name_local {
__be16 valuelen; /* number of bytes in value */
__u8 namelen; /* length of name bytes */
__u8 nameval[1]; /* name/value bytes */
} xfs_attr_leaf_name_local_t;
typedef struct xfs_attr_leaf_name_remote {
__be32 valueblk; /* block number of value bytes */
__be32 valuelen; /* number of bytes in value */
__u8 namelen; /* length of name bytes */
__u8 name[1]; /* name bytes */
} xfs_attr_leaf_name_remote_t;
typedef struct xfs_attr_leafblock {
xfs_attr_leaf_hdr_t hdr; /* constant-structure header block */
xfs_attr_leaf_entry_t entries[1]; /* sorted on key, not name */
xfs_attr_leaf_name_local_t namelist; /* grows from bottom of buf */
xfs_attr_leaf_name_remote_t valuelist; /* grows from bottom of buf */
} xfs_attr_leafblock_t;
/*
* CRC enabled leaf structures. Called "version 3" structures to match the
* version number of the directory and dablk structures for this feature, and
* attr2 is already taken by the variable inode attribute fork size feature.
*/
struct xfs_attr3_leaf_hdr {
struct xfs_da3_blkinfo info;
__be16 count;
__be16 usedbytes;
__be16 firstused;
__u8 holes;
__u8 pad1;
struct xfs_attr_leaf_map freemap[XFS_ATTR_LEAF_MAPSIZE];
__be32 pad2; /* 64 bit alignment */
};
#define XFS_ATTR3_LEAF_CRC_OFF (offsetof(struct xfs_attr3_leaf_hdr, info.crc))
struct xfs_attr3_leafblock {
struct xfs_attr3_leaf_hdr hdr;
struct xfs_attr_leaf_entry entries[1];
/*
* The rest of the block contains the following structures after the
* leaf entries, growing from the bottom up. The variables are never
* referenced, the locations accessed purely from helper functions.
*
* struct xfs_attr_leaf_name_local
* struct xfs_attr_leaf_name_remote
*/
};
/*
* incore, neutral version of the attribute leaf header
*/
struct xfs_attr3_icleaf_hdr {
__uint32_t forw;
__uint32_t back;
__uint16_t magic;
__uint16_t count;
__uint16_t usedbytes;
__uint16_t firstused;
__u8 holes;
struct {
__uint16_t base;
__uint16_t size;
} freemap[XFS_ATTR_LEAF_MAPSIZE];
};
/*
* Flags used in the leaf_entry[i].flags field.
* NOTE: the INCOMPLETE bit must not collide with the flags bits specified
* on the system call, they are "or"ed together for various operations.
*/
#define XFS_ATTR_LOCAL_BIT 0 /* attr is stored locally */
#define XFS_ATTR_ROOT_BIT 1 /* limit access to trusted attrs */
#define XFS_ATTR_SECURE_BIT 2 /* limit access to secure attrs */
#define XFS_ATTR_INCOMPLETE_BIT 7 /* attr in middle of create/delete */
#define XFS_ATTR_LOCAL (1 << XFS_ATTR_LOCAL_BIT)
#define XFS_ATTR_ROOT (1 << XFS_ATTR_ROOT_BIT)
#define XFS_ATTR_SECURE (1 << XFS_ATTR_SECURE_BIT)
#define XFS_ATTR_INCOMPLETE (1 << XFS_ATTR_INCOMPLETE_BIT)
/*
* Conversion macros for converting namespace bits from argument flags
* to ondisk flags.
*/
#define XFS_ATTR_NSP_ARGS_MASK (ATTR_ROOT | ATTR_SECURE)
#define XFS_ATTR_NSP_ONDISK_MASK (XFS_ATTR_ROOT | XFS_ATTR_SECURE)
#define XFS_ATTR_NSP_ONDISK(flags) ((flags) & XFS_ATTR_NSP_ONDISK_MASK)
#define XFS_ATTR_NSP_ARGS(flags) ((flags) & XFS_ATTR_NSP_ARGS_MASK)
#define XFS_ATTR_NSP_ARGS_TO_ONDISK(x) (((x) & ATTR_ROOT ? XFS_ATTR_ROOT : 0) |\
((x) & ATTR_SECURE ? XFS_ATTR_SECURE : 0))
#define XFS_ATTR_NSP_ONDISK_TO_ARGS(x) (((x) & XFS_ATTR_ROOT ? ATTR_ROOT : 0) |\
((x) & XFS_ATTR_SECURE ? ATTR_SECURE : 0))
/*
* Alignment for namelist and valuelist entries (since they are mixed
* there can be only one alignment value)
*/
#define XFS_ATTR_LEAF_NAME_ALIGN ((uint)sizeof(xfs_dablk_t))
static inline int
xfs_attr3_leaf_hdr_size(struct xfs_attr_leafblock *leafp)
{
if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
return sizeof(struct xfs_attr3_leaf_hdr);
return sizeof(struct xfs_attr_leaf_hdr);
}
static inline struct xfs_attr_leaf_entry *
xfs_attr3_leaf_entryp(xfs_attr_leafblock_t *leafp)
{
if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
return &((struct xfs_attr3_leafblock *)leafp)->entries[0];
return &leafp->entries[0];
}
/*
* Cast typed pointers for "local" and "remote" name/value structs.
*/
static inline char *
xfs_attr3_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
{
struct xfs_attr_leaf_entry *entries = xfs_attr3_leaf_entryp(leafp);
return &((char *)leafp)[be16_to_cpu(entries[idx].nameidx)];
}
static inline xfs_attr_leaf_name_remote_t *
xfs_attr3_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
{
return (xfs_attr_leaf_name_remote_t *)xfs_attr3_leaf_name(leafp, idx);
}
static inline xfs_attr_leaf_name_local_t *
xfs_attr3_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
{
return (xfs_attr_leaf_name_local_t *)xfs_attr3_leaf_name(leafp, idx);
}
/*
* Calculate total bytes used (including trailing pad for alignment) for
* a "local" name/value structure, a "remote" name/value structure, and
* a pointer which might be either.
*/
static inline int xfs_attr_leaf_entsize_remote(int nlen)
{
return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \
XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
}
static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
{
return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) +
XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
}
static inline int xfs_attr_leaf_entsize_local_max(int bsize)
{
return (((bsize) >> 1) + ((bsize) >> 2));
}
/*
* Used to keep a list of "remote value" extents when unlinking an inode.
*/
typedef struct xfs_attr_inactive_list {
xfs_dablk_t valueblk; /* block number of value bytes */
int valuelen; /* number of bytes in value */
} xfs_attr_inactive_list_t;
/*========================================================================
* Function prototypes for the kernel.
*========================================================================*/
/*
* Internal routines when attribute fork size < XFS_LITINO(mp).
*/
void xfs_attr_shortform_create(struct xfs_da_args *args);
void xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff);
int xfs_attr_shortform_lookup(struct xfs_da_args *args);
int xfs_attr_shortform_getvalue(struct xfs_da_args *args);
int xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
int xfs_attr_shortform_remove(struct xfs_da_args *args);
int xfs_attr_shortform_list(struct xfs_attr_list_context *context);
int xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
int xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
/*
* Internal routines when attribute fork size == XFS_LBSIZE(mp).
*/
int xfs_attr3_leaf_to_node(struct xfs_da_args *args);
int xfs_attr3_leaf_to_shortform(struct xfs_buf *bp,
struct xfs_da_args *args, int forkoff);
int xfs_attr3_leaf_clearflag(struct xfs_da_args *args);
int xfs_attr3_leaf_setflag(struct xfs_da_args *args);
int xfs_attr3_leaf_flipflags(struct xfs_da_args *args);
/*
* Routines used for growing the Btree.
*/
int xfs_attr3_leaf_split(struct xfs_da_state *state,
struct xfs_da_state_blk *oldblk,
struct xfs_da_state_blk *newblk);
int xfs_attr3_leaf_lookup_int(struct xfs_buf *leaf,
struct xfs_da_args *args);
int xfs_attr3_leaf_getvalue(struct xfs_buf *bp, struct xfs_da_args *args);
int xfs_attr3_leaf_add(struct xfs_buf *leaf_buffer,
struct xfs_da_args *args);
int xfs_attr3_leaf_remove(struct xfs_buf *leaf_buffer,
struct xfs_da_args *args);
int xfs_attr3_leaf_list_int(struct xfs_buf *bp,
struct xfs_attr_list_context *context);
/*
* Routines used for shrinking the Btree.
*/
int xfs_attr3_leaf_toosmall(struct xfs_da_state *state, int *retval);
void xfs_attr3_leaf_unbalance(struct xfs_da_state *state,
struct xfs_da_state_blk *drop_blk,
struct xfs_da_state_blk *save_blk);
int xfs_attr3_root_inactive(struct xfs_trans **trans, struct xfs_inode *dp);
/*
* Utility routines.
*/
xfs_dahash_t xfs_attr_leaf_lasthash(struct xfs_buf *bp, int *count);
int xfs_attr_leaf_order(struct xfs_buf *leaf1_bp,
struct xfs_buf *leaf2_bp);
int xfs_attr_leaf_newentsize(int namelen, int valuelen, int blocksize,
int *local);
int xfs_attr3_leaf_read(struct xfs_trans *tp, struct xfs_inode *dp,
xfs_dablk_t bno, xfs_daddr_t mappedbno,
struct xfs_buf **bpp);
void xfs_attr3_leaf_hdr_from_disk(struct xfs_attr3_icleaf_hdr *to,
struct xfs_attr_leafblock *from);
extern const struct xfs_buf_ops xfs_attr3_leaf_buf_ops;
#endif /* __XFS_ATTR_LEAF_H__ */