linux/fs/xfs/xfs_da_btree.h
Dave Chinner 32c5483a8a xfs: abstract the differences in dir2/dir3 via an ops vector
Lots of the dir code now goes through switches to determine what is
the correct on-disk format to parse. It generally involves a
"xfs_sbversion_hasfoo" check, deferencing the superblock version and
feature fields and hence touching several cache lines per operation
in the process. Some operations do multiple checks because they nest
conditional operations and they don't pass the information in a
direct fashion between each other.

Hence, add an ops vector to the xfs_inode structure that is
configured when the inode is initialised to point to all the correct
decode and encoding operations.  This will significantly reduce the
branchiness and cacheline footprint of the directory object decoding
and encoding.

This is the first patch in a series of conversion patches. It will
introduce the ops structure, the setup of it and add the first
operation to the vector. Subsequent patches will convert directory
ops one at a time to keep the changes simple and obvious.

Just this patch shows the benefit of such an approach on code size.
Just converting the two shortform dir operations as this patch does
decreases the built binary size by ~1500 bytes:

$ size fs/xfs/xfs.o.orig fs/xfs/xfs.o.p1
   text    data     bss     dec     hex filename
 794490   96802    1096  892388   d9de4 fs/xfs/xfs.o.orig
 792986   96802    1096  890884   d9804 fs/xfs/xfs.o.p1
$

That's a significant decrease in the instruction cache footprint of
the directory code for such a simple change, and indicates that this
approach is definitely worth pursuing further.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
2013-10-30 13:37:38 -05:00

204 lines
7.5 KiB
C

/*
* Copyright (c) 2000,2002,2005 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_DA_BTREE_H__
#define __XFS_DA_BTREE_H__
struct xfs_bmap_free;
struct xfs_inode;
struct xfs_trans;
struct zone;
struct xfs_dir_ops;
/*========================================================================
* Btree searching and modification structure definitions.
*========================================================================*/
/*
* Search comparison results
*/
enum xfs_dacmp {
XFS_CMP_DIFFERENT, /* names are completely different */
XFS_CMP_EXACT, /* names are exactly the same */
XFS_CMP_CASE /* names are same but differ in case */
};
/*
* Structure to ease passing around component names.
*/
typedef struct xfs_da_args {
const __uint8_t *name; /* string (maybe not NULL terminated) */
int namelen; /* length of string (maybe no NULL) */
__uint8_t filetype; /* filetype of inode for directories */
__uint8_t *value; /* set of bytes (maybe contain NULLs) */
int valuelen; /* length of value */
int flags; /* argument flags (eg: ATTR_NOCREATE) */
xfs_dahash_t hashval; /* hash value of name */
xfs_ino_t inumber; /* input/output inode number */
struct xfs_inode *dp; /* directory inode to manipulate */
xfs_fsblock_t *firstblock; /* ptr to firstblock for bmap calls */
struct xfs_bmap_free *flist; /* ptr to freelist for bmap_finish */
struct xfs_trans *trans; /* current trans (changes over time) */
xfs_extlen_t total; /* total blocks needed, for 1st bmap */
int whichfork; /* data or attribute fork */
xfs_dablk_t blkno; /* blkno of attr leaf of interest */
int index; /* index of attr of interest in blk */
xfs_dablk_t rmtblkno; /* remote attr value starting blkno */
int rmtblkcnt; /* remote attr value block count */
xfs_dablk_t blkno2; /* blkno of 2nd attr leaf of interest */
int index2; /* index of 2nd attr in blk */
xfs_dablk_t rmtblkno2; /* remote attr value starting blkno */
int rmtblkcnt2; /* remote attr value block count */
int op_flags; /* operation flags */
enum xfs_dacmp cmpresult; /* name compare result for lookups */
} xfs_da_args_t;
/*
* Operation flags:
*/
#define XFS_DA_OP_JUSTCHECK 0x0001 /* check for ok with no space */
#define XFS_DA_OP_RENAME 0x0002 /* this is an atomic rename op */
#define XFS_DA_OP_ADDNAME 0x0004 /* this is an add operation */
#define XFS_DA_OP_OKNOENT 0x0008 /* lookup/add op, ENOENT ok, else die */
#define XFS_DA_OP_CILOOKUP 0x0010 /* lookup to return CI name if found */
#define XFS_DA_OP_FLAGS \
{ XFS_DA_OP_JUSTCHECK, "JUSTCHECK" }, \
{ XFS_DA_OP_RENAME, "RENAME" }, \
{ XFS_DA_OP_ADDNAME, "ADDNAME" }, \
{ XFS_DA_OP_OKNOENT, "OKNOENT" }, \
{ XFS_DA_OP_CILOOKUP, "CILOOKUP" }
/*
* Storage for holding state during Btree searches and split/join ops.
*
* Only need space for 5 intermediate nodes. With a minimum of 62-way
* fanout to the Btree, we can support over 900 million directory blocks,
* which is slightly more than enough.
*/
typedef struct xfs_da_state_blk {
struct xfs_buf *bp; /* buffer containing block */
xfs_dablk_t blkno; /* filesystem blkno of buffer */
xfs_daddr_t disk_blkno; /* on-disk blkno (in BBs) of buffer */
int index; /* relevant index into block */
xfs_dahash_t hashval; /* last hash value in block */
int magic; /* blk's magic number, ie: blk type */
} xfs_da_state_blk_t;
typedef struct xfs_da_state_path {
int active; /* number of active levels */
xfs_da_state_blk_t blk[XFS_DA_NODE_MAXDEPTH];
} xfs_da_state_path_t;
typedef struct xfs_da_state {
xfs_da_args_t *args; /* filename arguments */
struct xfs_mount *mp; /* filesystem mount point */
unsigned int blocksize; /* logical block size */
unsigned int node_ents; /* how many entries in danode */
xfs_da_state_path_t path; /* search/split paths */
xfs_da_state_path_t altpath; /* alternate path for join */
unsigned char inleaf; /* insert into 1->lf, 0->splf */
unsigned char extravalid; /* T/F: extrablk is in use */
unsigned char extraafter; /* T/F: extrablk is after new */
xfs_da_state_blk_t extrablk; /* for double-splits on leaves */
/* for dirv2 extrablk is data */
} xfs_da_state_t;
/*
* Utility macros to aid in logging changed structure fields.
*/
#define XFS_DA_LOGOFF(BASE, ADDR) ((char *)(ADDR) - (char *)(BASE))
#define XFS_DA_LOGRANGE(BASE, ADDR, SIZE) \
(uint)(XFS_DA_LOGOFF(BASE, ADDR)), \
(uint)(XFS_DA_LOGOFF(BASE, ADDR)+(SIZE)-1)
/*
* Name ops for directory and/or attr name operations
*/
struct xfs_nameops {
xfs_dahash_t (*hashname)(struct xfs_name *);
enum xfs_dacmp (*compname)(struct xfs_da_args *,
const unsigned char *, int);
};
/*========================================================================
* Function prototypes.
*========================================================================*/
/*
* Routines used for growing the Btree.
*/
int xfs_da3_node_create(struct xfs_da_args *args, xfs_dablk_t blkno,
int level, struct xfs_buf **bpp, int whichfork);
int xfs_da3_split(xfs_da_state_t *state);
/*
* Routines used for shrinking the Btree.
*/
int xfs_da3_join(xfs_da_state_t *state);
void xfs_da3_fixhashpath(struct xfs_da_state *state,
struct xfs_da_state_path *path_to_to_fix);
/*
* Routines used for finding things in the Btree.
*/
int xfs_da3_node_lookup_int(xfs_da_state_t *state, int *result);
int xfs_da3_path_shift(xfs_da_state_t *state, xfs_da_state_path_t *path,
int forward, int release, int *result);
/*
* Utility routines.
*/
int xfs_da3_blk_link(xfs_da_state_t *state, xfs_da_state_blk_t *old_blk,
xfs_da_state_blk_t *new_blk);
int xfs_da3_node_read(struct xfs_trans *tp, struct xfs_inode *dp,
xfs_dablk_t bno, xfs_daddr_t mappedbno,
struct xfs_buf **bpp, int which_fork);
/*
* Utility routines.
*/
int xfs_da_grow_inode(xfs_da_args_t *args, xfs_dablk_t *new_blkno);
int xfs_da_grow_inode_int(struct xfs_da_args *args, xfs_fileoff_t *bno,
int count);
int xfs_da_get_buf(struct xfs_trans *trans, struct xfs_inode *dp,
xfs_dablk_t bno, xfs_daddr_t mappedbno,
struct xfs_buf **bp, int whichfork);
int xfs_da_read_buf(struct xfs_trans *trans, struct xfs_inode *dp,
xfs_dablk_t bno, xfs_daddr_t mappedbno,
struct xfs_buf **bpp, int whichfork,
const struct xfs_buf_ops *ops);
xfs_daddr_t xfs_da_reada_buf(struct xfs_trans *trans, struct xfs_inode *dp,
xfs_dablk_t bno, xfs_daddr_t mapped_bno,
int whichfork, const struct xfs_buf_ops *ops);
int xfs_da_shrink_inode(xfs_da_args_t *args, xfs_dablk_t dead_blkno,
struct xfs_buf *dead_buf);
uint xfs_da_hashname(const __uint8_t *name_string, int name_length);
enum xfs_dacmp xfs_da_compname(struct xfs_da_args *args,
const unsigned char *name, int len);
xfs_da_state_t *xfs_da_state_alloc(void);
void xfs_da_state_free(xfs_da_state_t *state);
extern struct kmem_zone *xfs_da_state_zone;
extern const struct xfs_nameops xfs_default_nameops;
#endif /* __XFS_DA_BTREE_H__ */