1 /* 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)buf.h 8.9 (Berkeley) 3/30/95 39 * $FreeBSD: src/sys/sys/buf.h,v 1.88.2.10 2003/01/25 19:02:23 dillon Exp $ 40 * $DragonFly: src/sys/sys/buf.h,v 1.24 2006/03/05 18:38:36 dillon Exp $ 41 */ 42 43 #ifndef _SYS_BUF_H_ 44 #define _SYS_BUF_H_ 45 46 #ifndef _SYS_QUEUE_H_ 47 #include <sys/queue.h> 48 #endif 49 #ifndef _SYS_LOCK_H_ 50 #include <sys/lock.h> 51 #endif 52 #ifndef _SYS_DEVICE_H_ 53 #include <sys/device.h> 54 #endif 55 56 #ifndef _SYS_XIO_H_ 57 #include <sys/xio.h> 58 #endif 59 #ifndef _SYS_TREE_H_ 60 #include <sys/tree.h> 61 #endif 62 #ifndef _SYS_BIO_H_ 63 #include <sys/bio.h> 64 #endif 65 #ifndef _SYS_SPINLOCK_H_ 66 #include <sys/spinlock.h> 67 #endif 68 69 struct buf; 70 struct bio; 71 struct mount; 72 struct vnode; 73 struct xio; 74 75 #define NBUF_BIO 4 76 77 struct buf_rb_tree; 78 struct buf_rb_hash; 79 RB_PROTOTYPE2(buf_rb_tree, buf, b_rbnode, rb_buf_compare, daddr_t, b_lblkno); 80 RB_PROTOTYPE2(buf_rb_hash, buf, b_rbhash, rb_buf_compare, daddr_t, b_lblkno); 81 82 /* 83 * To avoid including <ufs/ffs/softdep.h> 84 */ 85 LIST_HEAD(workhead, worklist); 86 /* 87 * These are currently used only by the soft dependency code, hence 88 * are stored once in a global variable. If other subsystems wanted 89 * to use these hooks, a pointer to a set of bio_ops could be added 90 * to each buffer. 91 */ 92 extern struct bio_ops { 93 void (*io_start) (struct buf *); 94 void (*io_complete) (struct buf *); 95 void (*io_deallocate) (struct buf *); 96 int (*io_fsync) (struct vnode *); 97 int (*io_sync) (struct mount *); 98 void (*io_movedeps) (struct buf *, struct buf *); 99 int (*io_countdeps) (struct buf *, int); 100 } bioops; 101 102 /* 103 * The buffer header describes an I/O operation in the kernel. 104 * 105 * NOTES: 106 * b_bufsize, b_bcount. b_bufsize is the allocation size of the 107 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the 108 * originally requested buffer size and can serve as a bounds check 109 * against EOF. For most, but not all uses, b_bcount == b_bufsize. 110 * 111 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned 112 * ranges of dirty data that need to be written to backing store. 113 * The range is typically clipped at b_bcount ( not b_bufsize ). 114 * 115 * b_resid. Number of bytes remaining in I/O. After an I/O operation 116 * completes, b_resid is usually 0 indicating 100% success. 117 * 118 * b_bio1 and b_bio2 represent the two primary I/O layers. Additional 119 * I/O layers are allocated out of the object cache and may also exist. 120 * 121 * b_bio1 is the logical layer and contains offset or block number 122 * data for the primary vnode, b_vp. I/O operations are almost 123 * universally initiated from the logical layer, so you will often 124 * see things like: vn_strategy(bp->b_vp, &bp->b_bio1). 125 * 126 * b_bio2 is the first physical layer (typically the slice-relative 127 * layer) and contains the translated offset or block number for 128 * the block device underlying a filesystem. Filesystems such as UFS 129 * will maintain cached translations and you may see them initiate 130 * a 'physical' I/O using vn_strategy(devvp, &bp->b_bio2). BUT, 131 * remember that the layering is relative to bp->b_vp, so the 132 * device-relative block numbers for buffer cache operations that occur 133 * directly on a block device will be in the first BIO layer. 134 * 135 * NOTE!!! Only the BIO subsystem accesses b_bio1 and b_bio2 directly. 136 * ALL STRATEGY LAYERS FOR BOTH VNODES AND DEVICES ONLY ACCESS THE BIO 137 * PASSED TO THEM, AND WILL PUSH ANOTHER BIO LAYER IF FORWARDING THE 138 * I/O DEEPER. In particular, a vn_strategy() or dev_dstrategy() 139 * call should not ever access buf->b_vp as this vnode may be totally 140 * unrelated to the vnode/device whos strategy routine was called. 141 */ 142 struct buf { 143 RB_ENTRY(buf) b_rbnode; /* RB node in vnode clean/dirty tree */ 144 RB_ENTRY(buf) b_rbhash; /* RB node in vnode hash tree */ 145 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */ 146 struct buf *b_cluster_next; /* Next buffer (cluster code) */ 147 struct vnode *b_vp; /* (vp, lblkno) index */ 148 struct bio b_bio_array[NBUF_BIO]; /* BIO translation layers */ 149 long b_flags; /* B_* flags. */ 150 unsigned short b_qindex; /* buffer queue index */ 151 unsigned char b_xflags; /* extra flags */ 152 struct lock b_lock; /* Buffer lock */ 153 long b_bufsize; /* Allocated buffer size. */ 154 long b_runningbufspace; /* when I/O is running, pipelining */ 155 long b_bcount; /* Valid bytes in buffer. */ 156 long b_resid; /* Remaining I/O */ 157 int b_error; /* Error return */ 158 caddr_t b_data; /* Memory, superblocks, indirect etc. */ 159 caddr_t b_kvabase; /* base kva for buffer */ 160 int b_kvasize; /* size of kva for buffer */ 161 int b_dirtyoff; /* Offset in buffer of dirty region. */ 162 int b_dirtyend; /* Offset of end of dirty region. */ 163 void *b_saveaddr; /* Original b_addr for physio. */ 164 struct xio b_xio; /* data buffer page list management */ 165 struct workhead b_dep; /* List of filesystem dependencies. */ 166 }; 167 168 /* 169 * XXX temporary 170 */ 171 #define b_bio1 b_bio_array[0] /* logical layer */ 172 #define b_bio2 b_bio_array[1] /* (typically) the disk layer */ 173 #define b_loffset b_bio1.bio_offset 174 #define b_lblkno b_bio1.bio_blkno 175 176 /* 177 * These flags are kept in b_flags. 178 * 179 * Notes: 180 * 181 * B_ASYNC VOP calls on bp's are usually async whether or not 182 * B_ASYNC is set, but some subsystems, such as NFS, like 183 * to know what is best for the caller so they can 184 * optimize the I/O. 185 * 186 * B_PAGING Indicates that bp is being used by the paging system or 187 * some paging system and that the bp is not linked into 188 * the b_vp's clean/dirty linked lists or ref counts. 189 * Buffer vp reassignments are illegal in this case. 190 * 191 * B_CACHE This may only be set if the buffer is entirely valid. 192 * The situation where B_DELWRI is set and B_CACHE is 193 * clear MUST be committed to disk by getblk() so 194 * B_DELWRI can also be cleared. See the comments for 195 * getblk() in kern/vfs_bio.c. If B_CACHE is clear, 196 * the caller is expected to clear B_ERROR|B_INVAL, 197 * set B_READ, and initiate an I/O. 198 * 199 * The 'entire buffer' is defined to be the range from 200 * 0 through b_bcount. 201 * 202 * B_MALLOC Request that the buffer be allocated from the malloc 203 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned. 204 * 205 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers 206 * by filesystems that allow clustering when the buffer 207 * is fully dirty and indicates that it may be clustered 208 * with other adjacent dirty buffers. Note the clustering 209 * may not be used with the stage 1 data write under NFS 210 * but may be used for the commit rpc portion. 211 * 212 * B_VMIO Indicates that the buffer is tied into an VM object. 213 * The buffer's data is always PAGE_SIZE aligned even 214 * if b_bufsize and b_bcount are not. ( b_bufsize is 215 * always at least DEV_BSIZE aligned, though ). 216 * 217 * B_DIRECT Hint that we should attempt to completely free 218 * the pages underlying the buffer. B_DIRECT is 219 * sticky until the buffer is released and typically 220 * only has an effect when B_RELBUF is also set. 221 * 222 * B_NOWDRAIN This flag should be set when a device (like VN) 223 * does a turn-around VOP_WRITE from its strategy 224 * routine. This flag prevents bwrite() from blocking 225 * in wdrain, avoiding a deadlock situation. 226 */ 227 228 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */ 229 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */ 230 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */ 231 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */ 232 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */ 233 #define B_CACHE 0x00000020 /* Bread found us in the cache. */ 234 #define B_HASHED 0x00000040 /* Indexed via v_rbhash_tree */ 235 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */ 236 #define B_FREEBUF 0x00000100 /* Instruct driver: free blocks */ 237 #define B_DONE 0x00000200 /* I/O completed. */ 238 #define B_EINTR 0x00000400 /* I/O was interrupted */ 239 #define B_ERROR 0x00000800 /* I/O error occurred. */ 240 #define B_UNUSED1000 0x00001000 /* Unused */ 241 #define B_INVAL 0x00002000 /* Does not contain valid info. */ 242 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */ 243 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */ 244 #define B_MALLOC 0x00010000 /* malloced b_data */ 245 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */ 246 #define B_PHYS 0x00040000 /* I/O to user memory. */ 247 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */ 248 #define B_READ 0x00100000 /* Read buffer. */ 249 #define B_DIRTY 0x00200000 /* Needs writing later. */ 250 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */ 251 #define B_WANT 0x00800000 /* Used by vm_pager.c */ 252 #define B_WRITE 0x00000000 /* Write buffer (pseudo flag). */ 253 #define B_UNUSED1000000 0x01000000 /* Unused */ 254 #define B_XXX 0x02000000 /* Debugging flag. */ 255 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */ 256 #define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */ 257 #define B_RAM 0x10000000 /* Read ahead mark (flag) */ 258 #define B_VMIO 0x20000000 /* VMIO flag */ 259 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */ 260 #define B_NOWDRAIN 0x80000000 /* Avoid wdrain deadlock */ 261 262 #define PRINT_BUF_FLAGS "\20\40nowdrain\37cluster\36vmio\35ram\34ordered" \ 263 "\33paging\32xxx\31writeinprog\30want\27relbuf\26dirty" \ 264 "\25read\24raw\23phys\22clusterok\21malloc\20nocache" \ 265 "\17locked\16inval\15scanned\14error\13eintr\12done\11freebuf" \ 266 "\10delwri\7call\6cache\4direct\3async\2needcommit\1age" 267 268 /* 269 * These flags are kept in b_xflags. 270 */ 271 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */ 272 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */ 273 #define BX_BKGRDWRITE 0x00000004 /* Do writes in background */ 274 #define BX_BKGRDINPROG 0x00000008 /* Background write in progress */ 275 #define BX_BKGRDWAIT 0x00000010 /* Background write waiting */ 276 #define BX_AUTOCHAINDONE 0x00000020 /* pager I/O chain auto mode */ 277 278 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */ 279 280 #ifdef _KERNEL 281 /* 282 * Buffer locking. See sys/buf2.h for inline functions. 283 */ 284 extern char *buf_wmesg; /* Default buffer lock message */ 285 #define BUF_WMESG "bufwait" 286 287 #endif /* _KERNEL */ 288 289 struct bio_queue_head { 290 TAILQ_HEAD(bio_queue, bio) queue; 291 daddr_t last_blkno; 292 struct bio *insert_point; 293 struct bio *switch_point; 294 }; 295 296 /* 297 * This structure describes a clustered I/O. It is stored in the b_saveaddr 298 * field of the buffer on which I/O is done. At I/O completion, cluster 299 * callback uses the structure to parcel I/O's to individual buffers, and 300 * then free's this structure. 301 */ 302 struct cluster_save { 303 long bs_bcount; /* Saved b_bcount. */ 304 long bs_bufsize; /* Saved b_bufsize. */ 305 void *bs_saveaddr; /* Saved b_addr. */ 306 int bs_nchildren; /* Number of associated buffers. */ 307 struct buf **bs_children; /* List of associated buffers. */ 308 }; 309 310 /* 311 * Zero out the buffer's data area. 312 */ 313 #define clrbuf(bp) { \ 314 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \ 315 (bp)->b_resid = 0; \ 316 } 317 318 /* 319 * Flags to low-level bitmap allocation routines (balloc). 320 * 321 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count 322 * to 127. 323 */ 324 #define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */ 325 #define B_SEQSHIFT 24 /* Sequential heuristic shift. */ 326 #define B_SEQMAX 0x7F 327 #define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */ 328 #define B_SYNC 0x02 /* Do all allocations synchronously. */ 329 330 #ifdef _KERNEL 331 extern int nbuf; /* The number of buffer headers */ 332 extern int maxswzone; /* Max KVA for swap structures */ 333 extern int maxbcache; /* Max KVA for buffer cache */ 334 extern int runningbufspace; 335 extern int buf_maxio; /* nominal maximum I/O for buffer */ 336 extern struct buf *buf; /* The buffer headers. */ 337 extern char *buffers; /* The buffer contents. */ 338 extern int bufpages; /* Number of memory pages in the buffer pool. */ 339 extern struct buf *swbuf; /* Swap I/O buffer headers. */ 340 extern int nswbuf; /* Number of swap I/O buffer headers. */ 341 342 struct uio; 343 344 void bufinit (void); 345 void bwillwrite (void); 346 int buf_dirty_count_severe (void); 347 void initbufbio(struct buf *); 348 void reinitbufbio(struct buf *); 349 void clearbiocache(struct bio *); 350 void bremfree (struct buf *); 351 int bread (struct vnode *, daddr_t, int, struct buf **); 352 int breadn (struct vnode *, daddr_t, int, daddr_t *, int *, int, 353 struct buf **); 354 int bwrite (struct buf *); 355 void bdwrite (struct buf *); 356 void bawrite (struct buf *); 357 void bdirty (struct buf *); 358 void bundirty (struct buf *); 359 int bowrite (struct buf *); 360 void brelse (struct buf *); 361 void bqrelse (struct buf *); 362 int vfs_bio_awrite (struct buf *); 363 struct buf *getpbuf (int *); 364 int inmem (struct vnode *, daddr_t); 365 struct buf *findblk (struct vnode *, daddr_t); 366 struct buf *getblk (struct vnode *, daddr_t, int, int, int); 367 struct buf *geteblk (int); 368 struct bio *push_bio(struct bio *); 369 void pop_bio(struct bio *); 370 int biowait (struct buf *); 371 void biodone (struct bio *); 372 373 void cluster_append(struct bio *, struct buf *); 374 int cluster_read (struct vnode *, u_quad_t, daddr_t, long, 375 long, int, struct buf **); 376 int cluster_wbuild (struct vnode *, long, daddr_t, int); 377 void cluster_write (struct buf *, u_quad_t, int); 378 int physio (dev_t dev, struct uio *uio, int ioflag); 379 #define physread physio 380 #define physwrite physio 381 void vfs_bio_set_validclean (struct buf *, int base, int size); 382 void vfs_bio_clrbuf (struct buf *); 383 void vfs_busy_pages (struct buf *, int clear_modify); 384 void vfs_unbusy_pages (struct buf *); 385 int vmapbuf (struct buf *); 386 void vunmapbuf (struct buf *); 387 void relpbuf (struct buf *, int *); 388 void brelvp (struct buf *); 389 void bgetvp (struct vnode *, struct buf *); 390 void pbgetvp (struct vnode *, struct buf *); 391 void pbrelvp (struct buf *); 392 int allocbuf (struct buf *bp, int size); 393 void reassignbuf (struct buf *); 394 struct buf *trypbuf (int *); 395 396 #endif /* _KERNEL */ 397 398 #endif /* !_SYS_BUF_H_ */ 399