228 lines
8.3 KiB
C
228 lines
8.3 KiB
C
/*
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* Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_DIR_LEAF_H__
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#define __XFS_DIR_LEAF_H__
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/*
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* Directory layout, internal structure, access macros, etc.
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*
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* Large directories are structured around Btrees where all the data
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* elements are in the leaf nodes. Filenames are hashed into an int,
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* then that int is used as the index into the Btree. Since the hashval
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* of a filename may not be unique, we may have duplicate keys. The
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* internal links in the Btree are logical block offsets into the file.
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*/
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struct uio;
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struct xfs_bmap_free;
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struct xfs_dabuf;
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struct xfs_da_args;
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struct xfs_da_state;
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struct xfs_da_state_blk;
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struct xfs_dir_put_args;
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struct xfs_inode;
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struct xfs_mount;
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struct xfs_trans;
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/*========================================================================
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* Directory Structure when equal to XFS_LBSIZE(mp) bytes.
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*========================================================================*/
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/*
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* This is the structure of the leaf nodes in the Btree.
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*
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* Struct leaf_entry's are packed from the top. Names grow from the bottom
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* but are not packed. The freemap contains run-length-encoded entries
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* for the free bytes after the leaf_entry's, but only the N largest such,
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* smaller runs are dropped. When the freemap doesn't show enough space
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* for an allocation, we compact the namelist area and try again. If we
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* still don't have enough space, then we have to split the block.
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*
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* Since we have duplicate hash keys, for each key that matches, compare
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* the actual string. The root and intermediate node search always takes
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* the first-in-the-block key match found, so we should only have to work
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* "forw"ard. If none matches, continue with the "forw"ard leaf nodes
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* until the hash key changes or the filename is found.
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*
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* The parent directory and the self-pointer are explicitly represented
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* (ie: there are entries for "." and "..").
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*
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* Note that the count being a __uint16_t limits us to something like a
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* blocksize of 1.3MB in the face of worst case (short) filenames.
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*/
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#define XFS_DIR_LEAF_MAPSIZE 3 /* how many freespace slots */
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typedef struct xfs_dir_leafblock {
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struct xfs_dir_leaf_hdr { /* constant-structure header block */
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xfs_da_blkinfo_t info; /* block type, links, etc. */
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__uint16_t count; /* count of active leaf_entry's */
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__uint16_t namebytes; /* num bytes of name strings stored */
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__uint16_t firstused; /* first used byte in name area */
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__uint8_t holes; /* != 0 if blk needs compaction */
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__uint8_t pad1;
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struct xfs_dir_leaf_map {/* RLE map of free bytes */
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__uint16_t base; /* base of free region */
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__uint16_t size; /* run length of free region */
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} freemap[XFS_DIR_LEAF_MAPSIZE]; /* N largest free regions */
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} hdr;
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struct xfs_dir_leaf_entry { /* sorted on key, not name */
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xfs_dahash_t hashval; /* hash value of name */
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__uint16_t nameidx; /* index into buffer of name */
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__uint8_t namelen; /* length of name string */
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__uint8_t pad2;
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} entries[1]; /* var sized array */
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struct xfs_dir_leaf_name {
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xfs_dir_ino_t inumber; /* inode number for this key */
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__uint8_t name[1]; /* name string itself */
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} namelist[1]; /* grows from bottom of buf */
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} xfs_dir_leafblock_t;
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typedef struct xfs_dir_leaf_hdr xfs_dir_leaf_hdr_t;
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typedef struct xfs_dir_leaf_map xfs_dir_leaf_map_t;
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typedef struct xfs_dir_leaf_entry xfs_dir_leaf_entry_t;
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typedef struct xfs_dir_leaf_name xfs_dir_leaf_name_t;
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/*
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* Length of name for which a 512-byte block filesystem
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* can get a double split.
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*/
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#define XFS_DIR_LEAF_CAN_DOUBLE_SPLIT_LEN \
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(512 - (uint)sizeof(xfs_dir_leaf_hdr_t) - \
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(uint)sizeof(xfs_dir_leaf_entry_t) * 2 - \
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(uint)sizeof(xfs_dir_leaf_name_t) * 2 - (MAXNAMELEN - 2) + 1 + 1)
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typedef int (*xfs_dir_put_t)(struct xfs_dir_put_args *pa);
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typedef union {
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xfs_off_t o; /* offset (cookie) */
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/*
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* Watch the order here (endian-ness dependent).
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*/
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struct {
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#ifndef XFS_NATIVE_HOST
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xfs_dahash_t h; /* hash value */
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__uint32_t be; /* block and entry */
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#else
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__uint32_t be; /* block and entry */
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xfs_dahash_t h; /* hash value */
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#endif /* XFS_NATIVE_HOST */
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} s;
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} xfs_dircook_t;
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#define XFS_PUT_COOKIE(c,mp,bno,entry,hash) \
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((c).s.be = XFS_DA_MAKE_BNOENTRY(mp, bno, entry), (c).s.h = (hash))
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typedef struct xfs_dir_put_args
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{
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xfs_dircook_t cook; /* cookie of (next) entry */
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xfs_intino_t ino; /* inode number */
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struct xfs_dirent *dbp; /* buffer pointer */
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char *name; /* directory entry name */
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int namelen; /* length of name */
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int done; /* output: set if value was stored */
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xfs_dir_put_t put; /* put function ptr (i/o) */
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struct uio *uio; /* uio control structure */
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} xfs_dir_put_args_t;
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#define XFS_DIR_LEAF_ENTSIZE_BYNAME(len) xfs_dir_leaf_entsize_byname(len)
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static inline int xfs_dir_leaf_entsize_byname(int len)
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{
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return (uint)sizeof(xfs_dir_leaf_name_t)-1 + len;
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}
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#define XFS_DIR_LEAF_ENTSIZE_BYENTRY(entry) \
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xfs_dir_leaf_entsize_byentry(entry)
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static inline int xfs_dir_leaf_entsize_byentry(xfs_dir_leaf_entry_t *entry)
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{
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return (uint)sizeof(xfs_dir_leaf_name_t)-1 + (entry)->namelen;
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}
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#define XFS_DIR_LEAF_NAMESTRUCT(leafp,offset) \
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xfs_dir_leaf_namestruct(leafp,offset)
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static inline xfs_dir_leaf_name_t *
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xfs_dir_leaf_namestruct(xfs_dir_leafblock_t *leafp, int offset)
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{
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return (xfs_dir_leaf_name_t *)&((char *)(leafp))[offset];
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}
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/*========================================================================
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* Function prototypes for the kernel.
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*========================================================================*/
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/*
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* Internal routines when dirsize < XFS_LITINO(mp).
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*/
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int xfs_dir_shortform_create(struct xfs_da_args *args, xfs_ino_t parent);
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int xfs_dir_shortform_addname(struct xfs_da_args *args);
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int xfs_dir_shortform_lookup(struct xfs_da_args *args);
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int xfs_dir_shortform_to_leaf(struct xfs_da_args *args);
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int xfs_dir_shortform_removename(struct xfs_da_args *args);
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int xfs_dir_shortform_getdents(struct xfs_inode *dp, struct uio *uio, int *eofp,
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struct xfs_dirent *dbp, xfs_dir_put_t put);
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int xfs_dir_shortform_replace(struct xfs_da_args *args);
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/*
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* Internal routines when dirsize == XFS_LBSIZE(mp).
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*/
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int xfs_dir_leaf_to_node(struct xfs_da_args *args);
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int xfs_dir_leaf_to_shortform(struct xfs_da_args *args);
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/*
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* Routines used for growing the Btree.
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*/
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int xfs_dir_leaf_split(struct xfs_da_state *state,
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struct xfs_da_state_blk *oldblk,
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struct xfs_da_state_blk *newblk);
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int xfs_dir_leaf_add(struct xfs_dabuf *leaf_buffer,
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struct xfs_da_args *args, int insertion_index);
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int xfs_dir_leaf_addname(struct xfs_da_args *args);
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int xfs_dir_leaf_lookup_int(struct xfs_dabuf *leaf_buffer,
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struct xfs_da_args *args,
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int *index_found_at);
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int xfs_dir_leaf_remove(struct xfs_trans *trans,
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struct xfs_dabuf *leaf_buffer,
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int index_to_remove);
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int xfs_dir_leaf_getdents_int(struct xfs_dabuf *bp, struct xfs_inode *dp,
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xfs_dablk_t bno, struct uio *uio,
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int *eobp, struct xfs_dirent *dbp,
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xfs_dir_put_t put, xfs_daddr_t nextda);
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/*
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* Routines used for shrinking the Btree.
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*/
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int xfs_dir_leaf_toosmall(struct xfs_da_state *state, int *retval);
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void xfs_dir_leaf_unbalance(struct xfs_da_state *state,
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struct xfs_da_state_blk *drop_blk,
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struct xfs_da_state_blk *save_blk);
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/*
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* Utility routines.
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*/
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uint xfs_dir_leaf_lasthash(struct xfs_dabuf *bp, int *count);
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int xfs_dir_leaf_order(struct xfs_dabuf *leaf1_bp,
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struct xfs_dabuf *leaf2_bp);
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int xfs_dir_put_dirent64_direct(xfs_dir_put_args_t *pa);
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int xfs_dir_put_dirent64_uio(xfs_dir_put_args_t *pa);
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int xfs_dir_ino_validate(struct xfs_mount *mp, xfs_ino_t ino);
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/*
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* Global data.
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*/
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extern xfs_dahash_t xfs_dir_hash_dot, xfs_dir_hash_dotdot;
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#endif /* __XFS_DIR_LEAF_H__ */
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