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38 * @(#)ufs_bmap.c 8.7 (Berkeley) 3/21/95
39 * $FreeBSD: src/sys/ufs/ufs/ufs_bmap.c,v 1.34.2.1 2000/03/17 10:12:14 ps Exp $
40 * $DragonFly: src/sys/vfs/ufs/ufs_bmap.c,v 1.13 2007/08/13 17:31:57 dillon Exp $
43 #include <sys/param.h>
44 #include <sys/systm.h>
47 #include <sys/vnode.h>
48 #include <sys/mount.h>
49 #include <sys/resourcevar.h>
55 #include "ufs_extern.h"
59 * Bmap converts the logical block number of a file to its physical block
60 * number on the disk. The conversion is done by using the logical block
61 * number to index into the array of block pointers described by the dinode.
63 * BMAP must return the contiguous before and after run in bytes, inclusive
64 * of the returned block.
66 * ufs_bmap(struct vnode *a_vp, off_t a_loffset,
67 * off_t *a_doffsetp, int *a_runp, int *a_runb)
70 ufs_bmap(struct vop_bmap_args
*ap
)
78 * Check for underlying vnode requests and ensure that logical
79 * to physical mapping is requested.
81 if (ap
->a_doffsetp
== NULL
)
84 fs
= VTOI(ap
->a_vp
)->i_fs
;
85 KKASSERT(((int)ap
->a_loffset
& ((1 << fs
->fs_bshift
) - 1)) == 0);
86 lbn
= ap
->a_loffset
>> fs
->fs_bshift
;
88 error
= ufs_bmaparray(ap
->a_vp
, lbn
, &dbn
, NULL
, NULL
,
89 ap
->a_runp
, ap
->a_runb
);
91 if (error
|| dbn
== (ufs_daddr_t
)-1) {
92 *ap
->a_doffsetp
= NOOFFSET
;
94 *ap
->a_doffsetp
= dbtodoff(fs
, dbn
);
96 *ap
->a_runp
= (*ap
->a_runp
+ 1) << fs
->fs_bshift
;
98 *ap
->a_runb
= *ap
->a_runb
<< fs
->fs_bshift
;
104 * Indirect blocks are now on the vnode for the file. They are given negative
105 * logical block numbers. Indirect blocks are addressed by the negative
106 * address of the first data block to which they point. Double indirect blocks
107 * are addressed by one less than the address of the first indirect block to
108 * which they point. Triple indirect blocks are addressed by one less than
109 * the address of the first double indirect block to which they point.
111 * ufs_bmaparray does the bmap conversion, and if requested returns the
112 * array of logical blocks which must be traversed to get to a block.
113 * Each entry contains the offset into that block that gets you to the
114 * next block and the disk address of the block (if it is assigned).
117 ufs_bmaparray(struct vnode
*vp
, ufs_daddr_t bn
, ufs_daddr_t
*bnp
,
118 struct indir
*ap
, int *nump
, int *runp
, int *runb
)
122 struct ufsmount
*ump
;
126 struct indir a
[NIADDR
+1], *xap
;
129 int error
, maxrun
, num
;
134 devvp
= ump
->um_devvp
;
137 if ((ap
!= NULL
&& nump
== NULL
) || (ap
== NULL
&& nump
!= NULL
))
138 panic("ufs_bmaparray: invalid arguments");
149 maxrun
= mp
->mnt_iosize_max
/ mp
->mnt_stat
.f_iosize
- 1;
151 xap
= ap
== NULL
? a
: ap
;
154 error
= ufs_getlbns(vp
, bn
, xap
, nump
);
160 *bnp
= blkptrtodb(ump
, ip
->i_db
[bn
]);
165 for (++bn
; bn
< NDADDR
&& *runp
< maxrun
&&
166 is_sequential(ump
, ip
->i_db
[bn
- 1], ip
->i_db
[bn
]);
169 if (runb
&& (bn
> 0)) {
170 for (--bn
; (bn
>= 0) && (*runb
< maxrun
) &&
171 is_sequential(ump
, ip
->i_db
[bn
],
180 /* Get disk address out of indirect block array */
181 daddr
= ip
->i_ib
[xap
->in_off
];
183 for (bp
= NULL
, ++xap
; --num
; ++xap
) {
185 * Exit the loop if there is no disk address assigned yet and
186 * the indirect block isn't in the cache, or if we were
187 * looking for an indirect block and we've found it.
190 metalbn
= xap
->in_lbn
;
191 if ((daddr
== 0 && !findblk(vp
, dbtodoff(fs
, metalbn
))) || metalbn
== bn
)
194 * If we get here, we've either got the block in the cache
195 * or we have a disk address for it, go fetch it.
201 bp
= getblk(vp
, lblktodoff(fs
, metalbn
),
202 mp
->mnt_stat
.f_iosize
, 0, 0);
203 if ((bp
->b_flags
& B_CACHE
) == 0) {
206 panic("ufs_bmaparray: indirect block not in cache");
208 bp
->b_bio2
.bio_offset
= fsbtodoff(fs
, daddr
);
209 bp
->b_flags
&= ~(B_INVAL
|B_ERROR
);
210 bp
->b_cmd
= BUF_CMD_READ
;
211 vfs_busy_pages(bp
->b_vp
, bp
);
212 vn_strategy(bp
->b_vp
, &bp
->b_bio1
);
220 daddr
= ((ufs_daddr_t
*)bp
->b_data
)[xap
->in_off
];
221 if (num
== 1 && daddr
&& runp
) {
222 for (bn
= xap
->in_off
+ 1;
223 bn
< MNINDIR(ump
) && *runp
< maxrun
&&
225 ((ufs_daddr_t
*)bp
->b_data
)[bn
- 1],
226 ((ufs_daddr_t
*)bp
->b_data
)[bn
]);
230 for(--bn
; bn
>= 0 && *runb
< maxrun
&&
231 is_sequential(ump
, ((daddr_t
*)bp
->b_data
)[bn
],
232 ((daddr_t
*)bp
->b_data
)[bn
+1]);
240 daddr
= blkptrtodb(ump
, daddr
);
241 *bnp
= daddr
== 0 ? -1 : daddr
;
246 * Create an array of logical block number/offset pairs which represent the
247 * path of indirect blocks required to access a data block. The first "pair"
248 * contains the logical block number of the appropriate single, double or
249 * triple indirect block and the offset into the inode indirect block array.
250 * Note, the logical block number of the inode single/double/triple indirect
251 * block appears twice in the array, once with the offset into the i_ib and
252 * once with the offset into the page itself.
255 ufs_getlbns(struct vnode
*vp
, ufs_daddr_t bn
, struct indir
*ap
, int *nump
)
257 long blockcnt
, metalbn
, realbn
;
258 struct ufsmount
*ump
;
259 int i
, numlevels
, off
;
262 ump
= VFSTOUFS(vp
->v_mount
);
270 /* The first NDADDR blocks are direct blocks. */
275 * Determine the number of levels of indirection. After this loop
276 * is done, blockcnt indicates the number of data blocks possible
277 * at the previous level of indirection, and NIADDR - i is the number
278 * of levels of indirection needed to locate the requested block.
280 for (blockcnt
= 1, i
= NIADDR
, bn
-= NDADDR
;; i
--, bn
-= blockcnt
) {
284 * Use int64_t's here to avoid overflow for triple indirect
285 * blocks when longs have 32 bits and the block size is more
288 qblockcnt
= (int64_t)blockcnt
* MNINDIR(ump
);
291 blockcnt
= qblockcnt
;
294 /* Calculate the address of the first meta-block. */
296 metalbn
= -(realbn
- bn
+ NIADDR
- i
);
298 metalbn
= -(-realbn
- bn
+ NIADDR
- i
);
301 * At each iteration, off is the offset into the bap array which is
302 * an array of disk addresses at the current level of indirection.
303 * The logical block number and the offset in that block are stored
304 * into the argument array.
306 ap
->in_lbn
= metalbn
;
307 ap
->in_off
= off
= NIADDR
- i
;
310 for (++numlevels
; i
<= NIADDR
; i
++) {
311 /* If searching for a meta-data block, quit when found. */
312 if (metalbn
== realbn
)
315 off
= (bn
/ blockcnt
) % MNINDIR(ump
);
318 ap
->in_lbn
= metalbn
;
323 metalbn
-= -1 + off
* blockcnt
;
324 blockcnt
/= MNINDIR(ump
);