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 1.22 2006/02/17 19:18:07 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 RB_PROTOTYPE(buf_rb_tree, buf, b_rbnode, rb_buf_compare); 79 80 /* 81 * To avoid including <ufs/ffs/softdep.h> 82 */ 83 LIST_HEAD(workhead, worklist); 84 /* 85 * These are currently used only by the soft dependency code, hence 86 * are stored once in a global variable. If other subsystems wanted 87 * to use these hooks, a pointer to a set of bio_ops could be added 88 * to each buffer. 89 */ 90 extern struct bio_ops { 91 void (*io_start) (struct buf *); 92 void (*io_complete) (struct buf *); 93 void (*io_deallocate) (struct buf *); 94 int (*io_fsync) (struct vnode *); 95 int (*io_sync) (struct mount *); 96 void (*io_movedeps) (struct buf *, struct buf *); 97 int (*io_countdeps) (struct buf *, int); 98 } bioops; 99 100 /* 101 * The buffer header describes an I/O operation in the kernel. 102 * 103 * NOTES: 104 * b_bufsize, b_bcount. b_bufsize is the allocation size of the 105 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the 106 * originally requested buffer size and can serve as a bounds check 107 * against EOF. For most, but not all uses, b_bcount == b_bufsize. 108 * 109 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned 110 * ranges of dirty data that need to be written to backing store. 111 * The range is typically clipped at b_bcount ( not b_bufsize ). 112 * 113 * b_resid. Number of bytes remaining in I/O. After an I/O operation 114 * completes, b_resid is usually 0 indicating 100% success. 115 * 116 * b_bio1 and b_bio2 represent the two primary I/O layers. Additional 117 * I/O layers are allocated out of the object cache and may also exist. 118 * 119 * b_bio1 is the logical layer and contains offset or block number 120 * data for the primary vnode, b_vp. I/O operations are almost 121 * universally initiated from the logical layer, so you will often 122 * see things like: vn_strategy(bp->b_vp, &bp->b_bio1). 123 * 124 * b_bio2 is the first physical layer (typically the slice-relative 125 * layer) and contains the translated offset or block number for 126 * the block device underlying a filesystem. Filesystems such as UFS 127 * will maintain cached translations and you may see them initiate 128 * a 'physical' I/O using vn_strategy(devvp, &bp->b_bio2). BUT, 129 * remember that the layering is relative to bp->b_vp, so the 130 * device-relative block numbers for buffer cache operations that occur 131 * directly on a block device will be in the first BIO layer. 132 * 133 * NOTE!!! Only the BIO subsystem accesses b_bio1 and b_bio2 directly. 134 * ALL STRATEGY LAYERS FOR BOTH VNODES AND DEVICES ONLY ACCESS THE BIO 135 * PASSED TO THEM, AND WILL PUSH ANOTHER BIO LAYER IF FORWARDING THE 136 * I/O DEEPER. In particular, a vn_strategy() or dev_dstrategy() 137 * call should not ever access buf->b_vp as this vnode may be totally 138 * unrelated to the vnode/device whos strategy routine was called. 139 */ 140 struct buf { 141 LIST_ENTRY(buf) b_hash; /* Hash chain. */ 142 RB_ENTRY(buf) b_rbnode; /* Red-Black node in vnode RB tree */ 143 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */ 144 struct buf *b_cluster_next; /* Next buffer (cluster code) */ 145 struct vnode *b_vp; /* (vp, lblkno) index */ 146 struct bio b_bio_array[NBUF_BIO]; /* BIO translation layers */ 147 long b_flags; /* B_* flags. */ 148 unsigned short b_qindex; /* buffer queue index */ 149 unsigned char b_xflags; /* extra flags */ 150 struct lock b_lock; /* Buffer lock */ 151 long b_bufsize; /* Allocated buffer size. */ 152 long b_runningbufspace; /* when I/O is running, pipelining */ 153 long b_bcount; /* Valid bytes in buffer. */ 154 long b_resid; /* Remaining I/O */ 155 int b_error; /* Error return */ 156 caddr_t b_data; /* Memory, superblocks, indirect etc. */ 157 caddr_t b_kvabase; /* base kva for buffer */ 158 int b_kvasize; /* size of kva for buffer */ 159 int b_dirtyoff; /* Offset in buffer of dirty region. */ 160 int b_dirtyend; /* Offset of end of dirty region. */ 161 void *b_saveaddr; /* Original b_addr for physio. */ 162 struct xio b_xio; /* data buffer page list management */ 163 struct workhead b_dep; /* List of filesystem dependencies. */ 164 }; 165 166 /* 167 * XXX temporary 168 */ 169 #define b_bio1 b_bio_array[0] /* logical layer */ 170 #define b_bio2 b_bio_array[1] /* (typically) the disk layer */ 171 #define b_loffset b_bio1.bio_offset 172 #define b_lblkno b_bio1.bio_blkno 173 174 /* 175 * These flags are kept in b_flags. 176 * 177 * Notes: 178 * 179 * B_ASYNC VOP calls on bp's are usually async whether or not 180 * B_ASYNC is set, but some subsystems, such as NFS, like 181 * to know what is best for the caller so they can 182 * optimize the I/O. 183 * 184 * B_PAGING Indicates that bp is being used by the paging system or 185 * some paging system and that the bp is not linked into 186 * the b_vp's clean/dirty linked lists or ref counts. 187 * Buffer vp reassignments are illegal in this case. 188 * 189 * B_CACHE This may only be set if the buffer is entirely valid. 190 * The situation where B_DELWRI is set and B_CACHE is 191 * clear MUST be committed to disk by getblk() so 192 * B_DELWRI can also be cleared. See the comments for 193 * getblk() in kern/vfs_bio.c. If B_CACHE is clear, 194 * the caller is expected to clear B_ERROR|B_INVAL, 195 * set B_READ, and initiate an I/O. 196 * 197 * The 'entire buffer' is defined to be the range from 198 * 0 through b_bcount. 199 * 200 * B_MALLOC Request that the buffer be allocated from the malloc 201 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned. 202 * 203 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers 204 * by filesystems that allow clustering when the buffer 205 * is fully dirty and indicates that it may be clustered 206 * with other adjacent dirty buffers. Note the clustering 207 * may not be used with the stage 1 data write under NFS 208 * but may be used for the commit rpc portion. 209 * 210 * B_VMIO Indicates that the buffer is tied into an VM object. 211 * The buffer's data is always PAGE_SIZE aligned even 212 * if b_bufsize and b_bcount are not. ( b_bufsize is 213 * always at least DEV_BSIZE aligned, though ). 214 * 215 * B_DIRECT Hint that we should attempt to completely free 216 * the pages underlying the buffer. B_DIRECT is 217 * sticky until the buffer is released and typically 218 * only has an effect when B_RELBUF is also set. 219 * 220 * B_NOWDRAIN This flag should be set when a device (like VN) 221 * does a turn-around VOP_WRITE from its strategy 222 * routine. This flag prevents bwrite() from blocking 223 * in wdrain, avoiding a deadlock situation. 224 */ 225 226 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */ 227 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */ 228 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */ 229 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */ 230 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */ 231 #define B_CACHE 0x00000020 /* Bread found us in the cache. */ 232 #define B_UNUSED40 0x00000040 /* Unused */ 233 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */ 234 #define B_FREEBUF 0x00000100 /* Instruct driver: free blocks */ 235 #define B_DONE 0x00000200 /* I/O completed. */ 236 #define B_EINTR 0x00000400 /* I/O was interrupted */ 237 #define B_ERROR 0x00000800 /* I/O error occurred. */ 238 #define B_UNUSED1000 0x00001000 /* Unused */ 239 #define B_INVAL 0x00002000 /* Does not contain valid info. */ 240 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */ 241 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */ 242 #define B_MALLOC 0x00010000 /* malloced b_data */ 243 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */ 244 #define B_PHYS 0x00040000 /* I/O to user memory. */ 245 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */ 246 #define B_READ 0x00100000 /* Read buffer. */ 247 #define B_DIRTY 0x00200000 /* Needs writing later. */ 248 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */ 249 #define B_WANT 0x00800000 /* Used by vm_pager.c */ 250 #define B_WRITE 0x00000000 /* Write buffer (pseudo flag). */ 251 #define B_UNUSED1000000 0x01000000 /* Unused */ 252 #define B_XXX 0x02000000 /* Debugging flag. */ 253 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */ 254 #define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */ 255 #define B_RAM 0x10000000 /* Read ahead mark (flag) */ 256 #define B_VMIO 0x20000000 /* VMIO flag */ 257 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */ 258 #define B_NOWDRAIN 0x80000000 /* Avoid wdrain deadlock */ 259 260 #define PRINT_BUF_FLAGS "\20\40nowdrain\37cluster\36vmio\35ram\34ordered" \ 261 "\33paging\32xxx\31writeinprog\30want\27relbuf\26dirty" \ 262 "\25read\24raw\23phys\22clusterok\21malloc\20nocache" \ 263 "\17locked\16inval\15scanned\14error\13eintr\12done\11freebuf" \ 264 "\10delwri\7call\6cache\4direct\3async\2needcommit\1age" 265 266 /* 267 * These flags are kept in b_xflags. 268 */ 269 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */ 270 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */ 271 #define BX_BKGRDWRITE 0x00000004 /* Do writes in background */ 272 #define BX_BKGRDINPROG 0x00000008 /* Background write in progress */ 273 #define BX_BKGRDWAIT 0x00000010 /* Background write waiting */ 274 #define BX_AUTOCHAINDONE 0x00000020 /* pager I/O chain auto mode */ 275 276 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */ 277 278 #ifdef _KERNEL 279 /* 280 * Buffer locking. See sys/buf2.h for inline functions. 281 */ 282 extern struct spinlock buftimespinlock; /* Interlock on setting prio and timo */ 283 extern char *buf_wmesg; /* Default buffer lock message */ 284 #define BUF_WMESG "bufwait" 285 286 #endif /* _KERNEL */ 287 288 struct bio_queue_head { 289 TAILQ_HEAD(bio_queue, bio) queue; 290 daddr_t last_blkno; 291 struct bio *insert_point; 292 struct bio *switch_point; 293 }; 294 295 /* 296 * This structure describes a clustered I/O. It is stored in the b_saveaddr 297 * field of the buffer on which I/O is done. At I/O completion, cluster 298 * callback uses the structure to parcel I/O's to individual buffers, and 299 * then free's this structure. 300 */ 301 struct cluster_save { 302 long bs_bcount; /* Saved b_bcount. */ 303 long bs_bufsize; /* Saved b_bufsize. */ 304 void *bs_saveaddr; /* Saved b_addr. */ 305 int bs_nchildren; /* Number of associated buffers. */ 306 struct buf **bs_children; /* List of associated buffers. */ 307 }; 308 309 /* 310 * Zero out the buffer's data area. 311 */ 312 #define clrbuf(bp) { \ 313 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \ 314 (bp)->b_resid = 0; \ 315 } 316 317 /* 318 * Flags to low-level bitmap allocation routines (balloc). 319 * 320 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count 321 * to 127. 322 */ 323 #define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */ 324 #define B_SEQSHIFT 24 /* Sequential heuristic shift. */ 325 #define B_SEQMAX 0x7F 326 #define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */ 327 #define B_SYNC 0x02 /* Do all allocations synchronously. */ 328 329 #ifdef _KERNEL 330 extern int nbuf; /* The number of buffer headers */ 331 extern int maxswzone; /* Max KVA for swap structures */ 332 extern int maxbcache; /* Max KVA for buffer cache */ 333 extern int runningbufspace; 334 extern int buf_maxio; /* nominal maximum I/O for buffer */ 335 extern struct buf *buf; /* The buffer headers. */ 336 extern char *buffers; /* The buffer contents. */ 337 extern int bufpages; /* Number of memory pages in the buffer pool. */ 338 extern struct buf *swbuf; /* Swap I/O buffer headers. */ 339 extern int nswbuf; /* Number of swap I/O buffer headers. */ 340 341 struct uio; 342 343 caddr_t bufhashinit (caddr_t); 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 struct buf *incore (struct vnode *, daddr_t); 365 struct buf *gbincore (struct vnode *, daddr_t); 366 int inmem (struct vnode *, daddr_t); 367 struct buf *getblk (struct vnode *, daddr_t, int, int, int); 368 struct buf *geteblk (int); 369 struct bio *push_bio(struct bio *); 370 void pop_bio(struct bio *); 371 int biowait (struct buf *); 372 void biodone (struct bio *); 373 374 void cluster_append(struct bio *, struct buf *); 375 int cluster_read (struct vnode *, u_quad_t, daddr_t, long, 376 long, int, struct buf **); 377 int cluster_wbuild (struct vnode *, long, daddr_t, int); 378 void cluster_write (struct buf *, u_quad_t, int); 379 int physio (dev_t dev, struct uio *uio, int ioflag); 380 #define physread physio 381 #define physwrite physio 382 void vfs_bio_set_validclean (struct buf *, int base, int size); 383 void vfs_bio_clrbuf (struct buf *); 384 void vfs_busy_pages (struct buf *, int clear_modify); 385 void vfs_unbusy_pages (struct buf *); 386 int vmapbuf (struct buf *); 387 void vunmapbuf (struct buf *); 388 void relpbuf (struct buf *, int *); 389 void brelvp (struct buf *); 390 void bgetvp (struct vnode *, struct buf *); 391 void pbgetvp (struct vnode *, struct buf *); 392 void pbrelvp (struct buf *); 393 int allocbuf (struct buf *bp, int size); 394 void reassignbuf (struct buf *, struct vnode *); 395 void pbreassignbuf (struct buf *, struct vnode *); 396 struct buf *trypbuf (int *); 397 398 #endif /* _KERNEL */ 399 400 #endif /* !_SYS_BUF_H_ */ 401