| 1 | /*␊ |
| 2 | * Copyright (c) 2000-2005 Apple Computer, Inc. All rights reserved.␊ |
| 3 | *␊ |
| 4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@␊ |
| 5 | * ␊ |
| 6 | * This file contains Original Code and/or Modifications of Original Code␊ |
| 7 | * as defined in and that are subject to the Apple Public Source License␊ |
| 8 | * Version 2.0 (the 'License'). You may not use this file except in␊ |
| 9 | * compliance with the License. The rights granted to you under the License␊ |
| 10 | * may not be used to create, or enable the creation or redistribution of,␊ |
| 11 | * unlawful or unlicensed copies of an Apple operating system, or to␊ |
| 12 | * circumvent, violate, or enable the circumvention or violation of, any␊ |
| 13 | * terms of an Apple operating system software license agreement.␊ |
| 14 | * ␊ |
| 15 | * Please obtain a copy of the License at␊ |
| 16 | * http://www.opensource.apple.com/apsl/ and read it before using this file.␊ |
| 17 | * ␊ |
| 18 | * The Original Code and all software distributed under the License are␊ |
| 19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER␊ |
| 20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,␊ |
| 21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,␊ |
| 22 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.␊ |
| 23 | * Please see the License for the specific language governing rights and␊ |
| 24 | * limitations under the License.␊ |
| 25 | * ␊ |
| 26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@␊ |
| 27 | */␊ |
| 28 | /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */␊ |
| 29 | /*␊ |
| 30 | * Copyright (c) 1982, 1986, 1989, 1993␊ |
| 31 | *␉The Regents of the University of California. All rights reserved.␊ |
| 32 | * (c) UNIX System Laboratories, Inc.␊ |
| 33 | * All or some portions of this file are derived from material licensed␊ |
| 34 | * to the University of California by American Telephone and Telegraph␊ |
| 35 | * Co. or Unix System Laboratories, Inc. and are reproduced herein with␊ |
| 36 | * the permission of UNIX System Laboratories, Inc.␊ |
| 37 | *␊ |
| 38 | * Redistribution and use in source and binary forms, with or without␊ |
| 39 | * modification, are permitted provided that the following conditions␊ |
| 40 | * are met:␊ |
| 41 | * 1. Redistributions of source code must retain the above copyright␊ |
| 42 | * notice, this list of conditions and the following disclaimer.␊ |
| 43 | * 2. Redistributions in binary form must reproduce the above copyright␊ |
| 44 | * notice, this list of conditions and the following disclaimer in the␊ |
| 45 | * documentation and/or other materials provided with the distribution.␊ |
| 46 | * 3. All advertising materials mentioning features or use of this software␊ |
| 47 | * must display the following acknowledgement:␊ |
| 48 | *␉This product includes software developed by the University of␊ |
| 49 | *␉California, Berkeley and its contributors.␊ |
| 50 | * 4. Neither the name of the University nor the names of its contributors␊ |
| 51 | * may be used to endorse or promote products derived from this software␊ |
| 52 | * without specific prior written permission.␊ |
| 53 | *␊ |
| 54 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND␊ |
| 55 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE␊ |
| 56 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE␊ |
| 57 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE␊ |
| 58 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL␊ |
| 59 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS␊ |
| 60 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)␊ |
| 61 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT␊ |
| 62 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY␊ |
| 63 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF␊ |
| 64 | * SUCH DAMAGE.␊ |
| 65 | *␊ |
| 66 | *␉@(#)buf.h␉8.9 (Berkeley) 3/30/95␊ |
| 67 | */␊ |
| 68 | ␊ |
| 69 | #ifndef _SYS_BUF_H_␊ |
| 70 | #define␉_SYS_BUF_H_␊ |
| 71 | ␊ |
| 72 | #include <sys/cdefs.h>␊ |
| 73 | #include <sys/kernel_types.h>␊ |
| 74 | #include <mach/memory_object_types.h>␊ |
| 75 | ␊ |
| 76 | ␊ |
| 77 | #define␉B_WRITE␉␉0x00000000␉/* Write buffer (pseudo flag). */␊ |
| 78 | #define␉B_READ␉␉0x00000001␉/* Read buffer. */␊ |
| 79 | #define␉B_ASYNC␉␉0x00000002␉/* Start I/O, do not wait. */␊ |
| 80 | #define␉B_NOCACHE␉0x00000004␉/* Do not cache block after use. */␊ |
| 81 | #define␉B_DELWRI␉0x00000008␉/* Delay I/O until buffer reused. */␊ |
| 82 | #define␉B_LOCKED␉0x00000010␉/* Locked in core (not reusable). */␊ |
| 83 | #define␉B_PHYS␉␉0x00000020␉/* I/O to user memory. */␊ |
| 84 | #define B_CLUSTER␉0x00000040␉/* UPL based I/O generated by cluster layer */␊ |
| 85 | #define␉B_PAGEIO␉0x00000080␉/* Page in/out */␊ |
| 86 | #define␉B_META␉␉0x00000100␉/* buffer contains meta-data. */␊ |
| 87 | #define␉B_RAW␉␉0x00000200␉/* Set by physio for raw transfers. */␊ |
| 88 | #define␉B_FUA␉␉0x00000400␉/* Write-through disk cache(if supported) */␊ |
| 89 | #define B_PASSIVE␉0x00000800␉/* PASSIVE I/Os are ignored by THROTTLE I/O */␊ |
| 90 | #define␉B_IOSTREAMING␉0x00001000␉/* sequential access pattern detected */␊ |
| 91 | #define B_THROTTLED_IO␉0x00002000␉/* low priority I/O */␊ |
| 92 | /*␊ |
| 93 | * make sure to check when adding flags that␊ |
| 94 | * that the new flags don't overlap the definitions␊ |
| 95 | * in buf_internal.h␊ |
| 96 | */␊ |
| 97 | ␊ |
| 98 | __BEGIN_DECLS␊ |
| 99 | ␊ |
| 100 | /*!␊ |
| 101 | @function buf_markaged␊ |
| 102 | @abstract Mark a buffer as "aged," i.e. as a good candidate to be discarded and reused after buf_brelse().␊ |
| 103 | @param bp Buffer to mark.␊ |
| 104 | */␊ |
| 105 | void␉buf_markaged(buf_t);␊ |
| 106 | ␊ |
| 107 | /*!␊ |
| 108 | @function buf_markinvalid␊ |
| 109 | @abstract Mark a buffer as not having valid data and being ready for immediate reuse after buf_brelse().␊ |
| 110 | @param bp Buffer to mark.␊ |
| 111 | */␊ |
| 112 | void␉buf_markinvalid(buf_t);␊ |
| 113 | ␊ |
| 114 | /*!␊ |
| 115 | @function buf_markdelayed␊ |
| 116 | @abstract Mark a buffer as a delayed write: mark it dirty without actually scheduling I/O.␊ |
| 117 | @discussion Data will be flushed to disk at some later time, not with brelse(). A sync()/fsync()␊ |
| 118 | or pressure necessitating reuse of the buffer will cause it to be written back to disk.␊ |
| 119 | @param bp Buffer to mark.␊ |
| 120 | */␊ |
| 121 | void␉buf_markdelayed(buf_t);␊ |
| 122 | ␊ |
| 123 | /*!␊ |
| 124 | @function buf_markeintr␊ |
| 125 | @abstract Mark a buffer as having been interrupted during I/O.␊ |
| 126 | @discussion Waiters for I/O to complete (buf_biowait()) will return with EINTR when woken up. ␊ |
| 127 | buf_markeintr does not itself do a wakeup.␊ |
| 128 | @param bp Buffer to mark.␊ |
| 129 | */␊ |
| 130 | void␉buf_markeintr(buf_t);␊ |
| 131 | ␊ |
| 132 | /*!␊ |
| 133 | @function buf_markfua␊ |
| 134 | @abstract Mark a buffer for write through disk cache, if disk supports it.␊ |
| 135 | @param bp Buffer to mark.␊ |
| 136 | */␊ |
| 137 | void␉buf_markfua(buf_t);␊ |
| 138 | ␊ |
| 139 | /*!␊ |
| 140 | @function buf_fua␊ |
| 141 | @abstract Check if a buffer is marked for write through disk caches.␊ |
| 142 | @param bp Buffer to test.␊ |
| 143 | @return Nonzero if buffer is marked for write-through, 0 if not.␊ |
| 144 | */␊ |
| 145 | int␉buf_fua(buf_t);␊ |
| 146 | ␊ |
| 147 | /*!␊ |
| 148 | @function buf_valid␊ |
| 149 | @abstract Check if a buffer contains valid data.␊ |
| 150 | @param bp Buffer to test.␊ |
| 151 | @return Nonzero if buffer has valid data, 0 if not.␊ |
| 152 | */␊ |
| 153 | int␉buf_valid(buf_t);␊ |
| 154 | ␊ |
| 155 | /*!␊ |
| 156 | @function buf_fromcache␊ |
| 157 | @abstract Check if a buffer's data was found in core.␊ |
| 158 | @discussion Will return truth after a buf_getblk that finds a valid buffer in the cache or the relevant␊ |
| 159 | data in core (but not in a buffer).␊ |
| 160 | @param bp Buffer to test.␊ |
| 161 | @return Nonzero if we got this buffer's data without doing I/O, 0 if not.␊ |
| 162 | */␊ |
| 163 | int␉buf_fromcache(buf_t);␊ |
| 164 | ␊ |
| 165 | /*!␊ |
| 166 | @function buf_upl␊ |
| 167 | @abstract Get the upl (Universal Page List) associated with a buffer.␊ |
| 168 | @discussion Buffers allocated with buf_alloc() are not returned with a upl, and␊ |
| 169 | traditional buffers only have a upl while an I/O is in progress.␊ |
| 170 | @param bp Buffer whose upl to grab.␊ |
| 171 | @return Buffer's upl if it has one, else NULL.␊ |
| 172 | */␊ |
| 173 | void *␉buf_upl(buf_t);␊ |
| 174 | ␊ |
| 175 | /*!␊ |
| 176 | @function buf_uploffset␊ |
| 177 | @abstract Get the offset into a UPL at which this buffer begins.␊ |
| 178 | @discussion This function should only be called on iobufs, i.e. buffers allocated with buf_alloc().␊ |
| 179 | @param bp Buffer whose uploffset to grab.␊ |
| 180 | @return Buffer's uploffset--does not check whether that value makes sense for this buffer.␊ |
| 181 | */␊ |
| 182 | uint32_t buf_uploffset(buf_t);␊ |
| 183 | ␊ |
| 184 | ␊ |
| 185 | ␊ |
| 186 | /*!␊ |
| 187 | @function buf_proc␊ |
| 188 | @abstract Get the process associated with this buffer.␊ |
| 189 | @discussion buf_proc() will generally return NULL; a process is currently only associated with␊ |
| 190 | a buffer in the event of a physio() call. ␊ |
| 191 | @param bp Buffer whose associated process to find.␊ |
| 192 | @return Associated process, possibly NULL.␊ |
| 193 | */␊ |
| 194 | proc_t␉buf_proc(buf_t);␊ |
| 195 | ␊ |
| 196 | /*!␊ |
| 197 | @function buf_dirtyoff␊ |
| 198 | @abstract Get the starting offset of the dirty region associated with a buffer.␊ |
| 199 | @discussion The dirty offset is zero unless someone explicitly calls buf_setdirtyoff() (which the kernel does not).␊ |
| 200 | @param bp Buffer whose dirty offset to get.␊ |
| 201 | @return Dirty offset (0 if not explicitly changed).␊ |
| 202 | */␊ |
| 203 | uint32_t buf_dirtyoff(buf_t);␊ |
| 204 | ␊ |
| 205 | /*!␊ |
| 206 | @function buf_dirtyend␊ |
| 207 | @abstract Get the ending offset of the dirty region associated with a buffer.␊ |
| 208 | @discussion If the buffer's data was found incore and dirty, the dirty end is the size of the block; otherwise, unless␊ |
| 209 | someone outside of xnu explicitly changes it by calling buf_setdirtyend(), it will be zero.␊ |
| 210 | @param bp Buffer whose dirty end to get.␊ |
| 211 | @return 0 if buffer is found clean; size of buffer if found dirty. Can be set to any value by callers of buf_setdirtyend().␊ |
| 212 | */␊ |
| 213 | uint32_t buf_dirtyend(buf_t);␊ |
| 214 | ␊ |
| 215 | /*!␊ |
| 216 | @function buf_setdirtyoff␊ |
| 217 | @abstract Set the starting offset of the dirty region associated with a buffer.␊ |
| 218 | @discussion This value is zero unless someone set it explicitly.␊ |
| 219 | @param bp Buffer whose dirty end to set.␊ |
| 220 | @return void.␊ |
| 221 | */␊ |
| 222 | void␉buf_setdirtyoff(buf_t, uint32_t);␊ |
| 223 | ␊ |
| 224 | /*!␊ |
| 225 | @function buf_setdirtyend␊ |
| 226 | @abstract Set the ending offset of the dirty region associated with a buffer.␊ |
| 227 | @discussion If the buffer's data was found incore and dirty, the dirty end is the size of the block; otherwise, unless␊ |
| 228 | someone outside of xnu explicitly changes it by calling buf_setdirtyend(), it will be zero.␊ |
| 229 | @param bp Buffer whose dirty end to set.␊ |
| 230 | @return void.␊ |
| 231 | */␊ |
| 232 | void␉buf_setdirtyend(buf_t, uint32_t);␊ |
| 233 | ␊ |
| 234 | /*!␊ |
| 235 | @function buf_error␊ |
| 236 | @abstract Get the error value associated with a buffer.␊ |
| 237 | @discussion Errors are set with buf_seterror().␊ |
| 238 | @param bp Buffer whose error value to retrieve.␊ |
| 239 | @return Error value, directly.␊ |
| 240 | */␊ |
| 241 | errno_t␉buf_error(buf_t);␊ |
| 242 | ␊ |
| 243 | /*!␊ |
| 244 | @function buf_seterror␊ |
| 245 | @abstract Set an error value on a buffer.␊ |
| 246 | @param bp Buffer whose error value to set.␊ |
| 247 | @return void.␊ |
| 248 | */␊ |
| 249 | void␉buf_seterror(buf_t, errno_t);␊ |
| 250 | ␊ |
| 251 | /*!␊ |
| 252 | @function buf_setflags␊ |
| 253 | @abstract Set flags on a buffer.␊ |
| 254 | @discussion: buffer_flags |= flags␊ |
| 255 | @param bp Buffer whose flags to set.␊ |
| 256 | @param flags Flags to add to buffer's mask. B_LOCKED/B_NOCACHE/B_ASYNC/B_READ/B_WRITE/B_PAGEIO/B_FUA␊ |
| 257 | @return void.␊ |
| 258 | */␊ |
| 259 | void␉buf_setflags(buf_t, int32_t);␊ |
| 260 | ␊ |
| 261 | /*!␊ |
| 262 | @function buf_clearflags␊ |
| 263 | @abstract Clear flags on a buffer.␊ |
| 264 | @discussion: buffer_flags &= ~flags␊ |
| 265 | @param bp Buffer whose flags to clear.␊ |
| 266 | @param flags Flags to remove from buffer's mask. B_LOCKED/B_NOCACHE/B_ASYNC/B_READ/B_WRITE/B_PAGEIO/B_FUA␊ |
| 267 | @return void.␊ |
| 268 | */␊ |
| 269 | void␉buf_clearflags(buf_t, int32_t);␊ |
| 270 | ␊ |
| 271 | /*!␊ |
| 272 | @function buf_flags␊ |
| 273 | @abstract Get flags set on a buffer.␊ |
| 274 | @discussion Valid flags are B_LOCKED/B_NOCACHE/B_ASYNC/B_READ/B_WRITE/B_PAGEIO/B_FUA.␊ |
| 275 | @param bp Buffer whose flags to grab.␊ |
| 276 | @return flags.␊ |
| 277 | */␊ |
| 278 | int32_t␉buf_flags(buf_t);␊ |
| 279 | ␊ |
| 280 | /*!␊ |
| 281 | @function buf_reset␊ |
| 282 | @abstract Reset I/O flag state on a buffer.␊ |
| 283 | @discussion Clears current flags on a buffer (internal and external) and allows some new flags to be set.␊ |
| 284 | Used perhaps to prepare an iobuf for reuse.␊ |
| 285 | @param bp Buffer whose flags to grab. ␊ |
| 286 | @param flags Flags to set on buffer: B_READ, B_WRITE, B_ASYNC, B_NOCACHE.␊ |
| 287 | @return void.␊ |
| 288 | */␊ |
| 289 | void␉buf_reset(buf_t, int32_t);␊ |
| 290 | ␊ |
| 291 | /*!␊ |
| 292 | @function buf_map␊ |
| 293 | @abstract Get virtual mappings for buffer data.␊ |
| 294 | @discussion For buffers created through buf_getblk() (i.e. traditional buffer cache usage), ␊ |
| 295 | buf_map() just returns the address at which data was mapped by but_getblk(). For a B_CLUSTER buffer, i.e. an iobuf␊ |
| 296 | whose upl state is managed manually, there are two possibilities. If the buffer was created␊ |
| 297 | with an underlying "real" buffer through cluster_bp(), the mapping of the "real" buffer is returned.␊ |
| 298 | Otherwise, the buffer was created with buf_alloc() and buf_setupl() was subsequently called; buf_map()␊ |
| 299 | will call ubc_upl_map() to get a mapping for the buffer's upl and return the start of that mapping␊ |
| 300 | plus the buffer's upl offset (set in buf_setupl()). In the last case, buf_unmap() must later be called␊ |
| 301 | to tear down the mapping. NOTE: buf_map() does not set the buffer data pointer; this must be done with buf_setdataptr().␊ |
| 302 | @param bp Buffer whose mapping to find or create.␊ |
| 303 | @param io_addr Destination for mapping address.␊ |
| 304 | @return 0 for success, ENOMEM if unable to map the buffer.␊ |
| 305 | */␊ |
| 306 | errno_t␉buf_map(buf_t, caddr_t *);␊ |
| 307 | ␊ |
| 308 | /*!␊ |
| 309 | @function buf_unmap␊ |
| 310 | @abstract Release mappings for buffer data.␊ |
| 311 | @discussion For buffers created through buf_getblk() (i.e. traditional buffer cache usage), ␊ |
| 312 | buf_unmap() does nothing; buf_brelse() will take care of unmapping. For a B_CLUSTER buffer, i.e. an iobuf␊ |
| 313 | whose upl state is managed manually, there are two possibilities. If the buffer was created␊ |
| 314 | with an underlying "real" buffer through cluster_bp(), buf_unmap() does nothing; buf_brelse() on the␊ |
| 315 | underlying buffer will tear down the mapping. Otherwise, the buffer was created with buf_alloc() and ␊ |
| 316 | buf_setupl() was subsequently called; buf_map() created the mapping. In this case, buf_unmap() will␊ |
| 317 | unmap the buffer.␊ |
| 318 | @param bp Buffer whose mapping to find or create.␊ |
| 319 | @param io_addr Destination for mapping address.␊ |
| 320 | @return 0 for success, EINVAL if unable to unmap buffer.␊ |
| 321 | */␊ |
| 322 | errno_t␉buf_unmap(buf_t);␊ |
| 323 | ␊ |
| 324 | /*!␊ |
| 325 | @function buf_setdrvdata␊ |
| 326 | @abstract Set driver-specific data on a buffer.␊ |
| 327 | @param bp Buffer whose driver-data to set.␊ |
| 328 | @param drvdata Opaque driver data.␊ |
| 329 | @return void.␊ |
| 330 | */␊ |
| 331 | void ␉buf_setdrvdata(buf_t, void *);␊ |
| 332 | ␊ |
| 333 | /*!␊ |
| 334 | @function buf_setdrvdata␊ |
| 335 | @abstract Get driver-specific data from a buffer.␊ |
| 336 | @param bp Buffer whose driver data to get.␊ |
| 337 | @return Opaque driver data.␊ |
| 338 | */␊ |
| 339 | void *␉buf_drvdata(buf_t);␊ |
| 340 | ␊ |
| 341 | /*!␊ |
| 342 | @function buf_setfsprivate␊ |
| 343 | @abstract Set filesystem-specific data on a buffer.␊ |
| 344 | @param bp Buffer whose filesystem data to set.␊ |
| 345 | @param fsprivate Opaque filesystem data.␊ |
| 346 | @return void.␊ |
| 347 | */␊ |
| 348 | void ␉buf_setfsprivate(buf_t, void *);␊ |
| 349 | ␊ |
| 350 | /*!␊ |
| 351 | @function buf_fsprivate␊ |
| 352 | @abstract Get filesystem-specific data from a buffer.␊ |
| 353 | @param bp Buffer whose filesystem data to get.␊ |
| 354 | @return Opaque filesystem data.␊ |
| 355 | */␊ |
| 356 | void *␉buf_fsprivate(buf_t);␊ |
| 357 | ␊ |
| 358 | /*!␊ |
| 359 | @function buf_blkno␊ |
| 360 | @abstract Get physical block number associated with a buffer, in the sense of VNOP_BLOCKMAP.␊ |
| 361 | @discussion When a buffer's physical block number is the same is its logical block number, then the physical␊ |
| 362 | block number is considered uninitialized. A physical block number of -1 indicates that there is no valid␊ |
| 363 | physical mapping (e.g. the logical block is invalid or corresponds to a sparse region in a file). Physical␊ |
| 364 | block number is normally set by the cluster layer or by buf_getblk().␊ |
| 365 | @param bp Buffer whose physical block number to get.␊ |
| 366 | @return Block number.␊ |
| 367 | */␊ |
| 368 | daddr64_t buf_blkno(buf_t);␊ |
| 369 | ␊ |
| 370 | /*!␊ |
| 371 | @function buf_lblkno␊ |
| 372 | @abstract Get logical block number associated with a buffer.␊ |
| 373 | @discussion Logical block number is set on traditionally-used buffers by an argument passed to buf_getblk(),␊ |
| 374 | for example by buf_bread().␊ |
| 375 | @param bp Buffer whose logical block number to get.␊ |
| 376 | @return Block number.␊ |
| 377 | */␊ |
| 378 | daddr64_t buf_lblkno(buf_t);␊ |
| 379 | ␊ |
| 380 | /*!␊ |
| 381 | @function buf_setblkno␊ |
| 382 | @abstract Set physical block number associated with a buffer.␊ |
| 383 | @discussion Physical block number is generally set by the cluster layer or by buf_getblk().␊ |
| 384 | @param bp Buffer whose physical block number to set.␊ |
| 385 | @param blkno Block number to set.␊ |
| 386 | @return void.␊ |
| 387 | */␊ |
| 388 | void␉buf_setblkno(buf_t, daddr64_t);␊ |
| 389 | ␊ |
| 390 | /*!␊ |
| 391 | @function buf_setlblkno␊ |
| 392 | @abstract Set logical block number associated with a buffer.␊ |
| 393 | @discussion Logical block number is set on traditionally-used buffers by an argument passed to buf_getblk(),␊ |
| 394 | for example by buf_bread().␊ |
| 395 | @param bp Buffer whose logical block number to set.␊ |
| 396 | @param lblkno Block number to set.␊ |
| 397 | @return void.␊ |
| 398 | */␊ |
| 399 | void␉buf_setlblkno(buf_t, daddr64_t);␊ |
| 400 | ␊ |
| 401 | /*!␊ |
| 402 | @function buf_count␊ |
| 403 | @abstract Get count of valid bytes in a buffer. This may be less than the space allocated to the buffer.␊ |
| 404 | @param bp Buffer whose byte count to get.␊ |
| 405 | @return Byte count.␊ |
| 406 | */␊ |
| 407 | uint32_t buf_count(buf_t);␊ |
| 408 | ␊ |
| 409 | /*!␊ |
| 410 | @function buf_size␊ |
| 411 | @abstract Get size of data region allocated to a buffer.␊ |
| 412 | @discussion May be larger than amount of valid data in buffer.␊ |
| 413 | @param bp Buffer whose size to get.␊ |
| 414 | @return Size.␊ |
| 415 | */␊ |
| 416 | uint32_t buf_size(buf_t);␊ |
| 417 | ␊ |
| 418 | /*!␊ |
| 419 | @function buf_resid␊ |
| 420 | @abstract Get a count of bytes which were not consumed by an I/O on a buffer.␊ |
| 421 | @discussion Set when an I/O operations completes.␊ |
| 422 | @param bp Buffer whose outstanding count to get.␊ |
| 423 | @return Count of unwritten/unread bytes.␊ |
| 424 | */␊ |
| 425 | uint32_t buf_resid(buf_t);␊ |
| 426 | ␊ |
| 427 | /*!␊ |
| 428 | @function buf_setcount␊ |
| 429 | @abstract Set count of valid bytes in a buffer. This may be less than the space allocated to the buffer.␊ |
| 430 | @param bp Buffer whose byte count to set.␊ |
| 431 | @param bcount Count to set.␊ |
| 432 | @return void.␊ |
| 433 | */␊ |
| 434 | void␉buf_setcount(buf_t, uint32_t);␊ |
| 435 | ␊ |
| 436 | /*!␊ |
| 437 | @function buf_setsize␊ |
| 438 | @abstract Set size of data region allocated to a buffer.␊ |
| 439 | @discussion May be larger than amount of valid data in buffer. Should be used by ␊ |
| 440 | code which is manually providing storage for an iobuf, one allocated with buf_alloc().␊ |
| 441 | @param bp Buffer whose size to set.␊ |
| 442 | @return void.␊ |
| 443 | */␊ |
| 444 | void␉buf_setsize(buf_t, uint32_t);␊ |
| 445 | ␊ |
| 446 | /*!␊ |
| 447 | @function buf_setresid␊ |
| 448 | @abstract Set a count of bytes outstanding for I/O in a buffer.␊ |
| 449 | @discussion Set when an I/O operations completes. Examples: called by IOStorageFamily when I/O␊ |
| 450 | completes, often called on an "original" buffer when using a manipulated buffer to perform I/O ␊ |
| 451 | on behalf of the first.␊ |
| 452 | @param bp Buffer whose outstanding count to set.␊ |
| 453 | @return Count of unwritten/unread bytes.␊ |
| 454 | */␊ |
| 455 | void␉buf_setresid(buf_t, uint32_t);␊ |
| 456 | ␊ |
| 457 | /*!␊ |
| 458 | @function buf_setdataptr␊ |
| 459 | @abstract Set the address at which a buffer's data will be stored.␊ |
| 460 | @discussion In traditional buffer use, the data pointer will be set automatically. This routine is␊ |
| 461 | useful with iobufs (allocated with buf_alloc()).␊ |
| 462 | @param bp Buffer whose data pointer to set.␊ |
| 463 | @param data Pointer to data region.␊ |
| 464 | @return void.␊ |
| 465 | */␊ |
| 466 | void␉buf_setdataptr(buf_t, uintptr_t);␊ |
| 467 | ␊ |
| 468 | /*!␊ |
| 469 | @function buf_dataptr␊ |
| 470 | @abstract Get the address at which a buffer's data is stored; for iobufs, this must␊ |
| 471 | be set with buf_setdataptr(). See buf_map().␊ |
| 472 | @param bp Buffer whose data pointer to retrieve.␊ |
| 473 | @return Data pointer; NULL if unset.␊ |
| 474 | */␊ |
| 475 | uintptr_t buf_dataptr(buf_t);␊ |
| 476 | ␊ |
| 477 | /*!␊ |
| 478 | @function buf_vnode␊ |
| 479 | @abstract Get the vnode associated with a buffer.␊ |
| 480 | @discussion Every buffer is associated with a file. Because there is an I/O in flight,␊ |
| 481 | there is an iocount on this vnode; it is returned WITHOUT an extra iocount, and vnode_put()␊ |
| 482 | need NOT be called.␊ |
| 483 | @param bp Buffer whose vnode to retrieve.␊ |
| 484 | @return Buffer's vnode.␊ |
| 485 | */␊ |
| 486 | vnode_t␉buf_vnode(buf_t);␊ |
| 487 | ␊ |
| 488 | /*!␊ |
| 489 | @function buf_setvnode␊ |
| 490 | @abstract Set the vnode associated with a buffer.␊ |
| 491 | @discussion This call need not be used on traditional buffers; it is for use with iobufs.␊ |
| 492 | @param bp Buffer whose vnode to set.␊ |
| 493 | @param vp The vnode to attach to the buffer.␊ |
| 494 | @return void.␊ |
| 495 | */␊ |
| 496 | void␉buf_setvnode(buf_t, vnode_t);␊ |
| 497 | ␊ |
| 498 | /*!␊ |
| 499 | @function buf_setdevice␊ |
| 500 | @abstract Set the device associated with a buffer.␊ |
| 501 | @discussion A buffer's device is set in buf_strategy() (or in buf_getblk() if the file is a device). ␊ |
| 502 | It is also set on an iobuf if buf_alloc() is passed a device vnode.␊ |
| 503 | @param bp Buffer whose device ID to set.␊ |
| 504 | @param vp Device to set on the buffer.␊ |
| 505 | @return 0 for success, EINVAL if vp is not a device file.␊ |
| 506 | */␊ |
| 507 | errno_t␉buf_setdevice(buf_t, vnode_t);␊ |
| 508 | ␊ |
| 509 | /*!␊ |
| 510 | @function buf_strategy␊ |
| 511 | @abstract Pass an I/O request for a buffer down to the device layer.␊ |
| 512 | @discussion This is one of the most important routines in the buffer cache layer. For buffers obtained␊ |
| 513 | through buf_getblk, it handles finding physical block numbers for the I/O (with VNOP_BLKTOOFF and ␊ |
| 514 | VNOP_BLOCKMAP), packaging the I/O into page-sized chunks, and initiating I/O on the disk by calling ␊ |
| 515 | the device's strategy routine. If a buffer's UPL has been set manually with buf_setupl(), it assumes ␊ |
| 516 | that the request is already correctly configured with a block number and a size divisible by page size␊ |
| 517 | and will just call directly to the device.␊ |
| 518 | @param devvp Device on which to perform I/O␊ |
| 519 | @param ap vnop_strategy_args structure (most importantly, a buffer).␊ |
| 520 | @return 0 for success, or errors from filesystem or device layers.␊ |
| 521 | */␊ |
| 522 | errno_t␉buf_strategy(vnode_t, void *);␊ |
| 523 | ␊ |
| 524 | /* ␊ |
| 525 | * Flags for buf_invalblkno() ␊ |
| 526 | */␊ |
| 527 | #define␉BUF_WAIT␉0x01␊ |
| 528 | ␊ |
| 529 | /*!␊ |
| 530 | @function buf_invalblkno␊ |
| 531 | @abstract Invalidate a filesystem logical block in a file.␊ |
| 532 | @discussion buf_invalblkno() tries to make the data for a given block in a file␊ |
| 533 | invalid; if the buffer for that block is found in core and is not busy, we mark it ␊ |
| 534 | invalid and call buf_brelse() (see "flags" param for what happens if the buffer is busy).␊ |
| 535 | buf_brelse(), noticing that it is invalid, will ␊ |
| 536 | will return the buffer to the empty-buffer list and tell the VM subsystem to abandon ␊ |
| 537 | the relevant pages. Data will not be written to backing store--it will be cast aside.␊ |
| 538 | Note that this function will only work if the block in question has been␊ |
| 539 | obtained with a buf_getblk(). If data has been read into core without using␊ |
| 540 | traditional buffer cache routines, buf_invalblkno() will not be able to invalidate it--this␊ |
| 541 | includes the use of iobufs.␊ |
| 542 | @param bp Buffer whose block to invalidate.␊ |
| 543 | @param lblkno Logical block number.␊ |
| 544 | @param flags BUF_WAIT: wait for busy buffers to become unbusy and invalidate them then. Otherwise,␊ |
| 545 | just return EBUSY for busy blocks.␊ |
| 546 | @return 0 for success, EINVAL if vp is not a device file.␊ |
| 547 | */␊ |
| 548 | errno_t␉buf_invalblkno(vnode_t, daddr64_t, int);␊ |
| 549 | ␊ |
| 550 | /*!␊ |
| 551 | @function buf_callback␊ |
| 552 | @abstract Get the function set to be called when I/O on a buffer completes.␊ |
| 553 | @discussion A function returned by buf_callback was originally set with buf_setcallback().␊ |
| 554 | @param bp Buffer whose callback to get.␊ |
| 555 | @return 0 for success, or errors from filesystem or device layers.␊ |
| 556 | */␊ |
| 557 | void * buf_callback(buf_t);␊ |
| 558 | ␊ |
| 559 | /*!␊ |
| 560 | @function buf_setcallback␊ |
| 561 | @abstract Set a function to be called once when I/O on a buffer completes.␊ |
| 562 | @discussion A one-shot callout set with buf_setcallback() will be called from buf_biodone()␊ |
| 563 | when I/O completes. It will be passed the "transaction" argument as well as the buffer.␊ |
| 564 | buf_setcallback() also marks the buffer as B_ASYNC.␊ |
| 565 | @param bp Buffer whose callback to set.␊ |
| 566 | @param callback function to use as callback.␊ |
| 567 | @param transaction Additional argument to callback function.␊ |
| 568 | @return 0; always succeeds.␊ |
| 569 | */␊ |
| 570 | errno_t␉buf_setcallback(buf_t, void (*)(buf_t, void *), void *);␊ |
| 571 | ␊ |
| 572 | /*!␊ |
| 573 | @function buf_setupl␊ |
| 574 | @abstract Set the UPL (Universal Page List), and offset therein, on a buffer.␊ |
| 575 | @discussion buf_setupl() should only be called on buffers allocated with buf_alloc().␊ |
| 576 | A subsequent call to buf_map() will map the UPL and give back the address at which data␊ |
| 577 | begins. After buf_setupl() is called, a buffer is marked B_CLUSTER; when this is the case,␊ |
| 578 | buf_strategy() assumes that a buffer is correctly configured to be passed to the device␊ |
| 579 | layer without modification. Passing a NULL upl will clear the upl and the B_CLUSTER flag on the␊ |
| 580 | buffer.␊ |
| 581 | @param bp Buffer whose upl to set.␊ |
| 582 | @param upl UPL to set in the buffer.␊ |
| 583 | @parma offset Offset within upl at which relevant data begin.␊ |
| 584 | @return 0 for success, EINVAL if the buffer was not allocated with buf_alloc().␊ |
| 585 | */␊ |
| 586 | errno_t␉buf_setupl(buf_t, upl_t, uint32_t);␊ |
| 587 | ␊ |
| 588 | /*!␊ |
| 589 | @function buf_clone␊ |
| 590 | @abstract Clone a buffer with a restricted range and an optional callback.␊ |
| 591 | @discussion Generates a buffer which is identical to its "bp" argument except that␊ |
| 592 | it spans a subset of the data of the original. The buffer to be cloned should␊ |
| 593 | have been allocated with buf_alloc(). Checks its arguments to make sure␊ |
| 594 | that the data subset is coherent. Optionally, adds a callback function and argument to it␊ |
| 595 | to be called when I/O completes (as with buf_setcallback(), but B_ASYNC is not set). If the original buffer had␊ |
| 596 | a upl set through buf_setupl(), this upl is copied to the new buffer; otherwise, the original's␊ |
| 597 | data pointer is used raw. The buffer must be released with buf_free().␊ |
| 598 | @param bp Buffer to clone.␊ |
| 599 | @param io_offset Offset, relative to start of data in original buffer, at which new buffer's data will begin. ␊ |
| 600 | @param io_size Size of buffer region in new buffer, in the sense of buf_count().␊ |
| 601 | @param iodone Callback to be called from buf_biodone() when I/O completes, in the sense of buf_setcallback().␊ |
| 602 | @param arg Argument to pass to iodone() callback.␊ |
| 603 | @return NULL if io_offset/io_size combination is invalid for the buffer to be cloned; otherwise, the new buffer.␊ |
| 604 | */␊ |
| 605 | buf_t␉buf_clone(buf_t, int, int, void (*)(buf_t, void *), void *);␊ |
| 606 | ␊ |
| 607 | /*!␊ |
| 608 | @function buf_alloc␊ |
| 609 | @abstract Allocate an uninitialized buffer.␊ |
| 610 | @discussion A buffer returned by buf_alloc() is marked as busy and as an iobuf; it has no storage set up and must be␊ |
| 611 | set up using buf_setdataptr() or buf_setupl()/buf_map().␊ |
| 612 | @param vp vnode to associate with the buffer: optionally NULL. If vp is a device file, then␊ |
| 613 | the buffer's associated device will be set. If vp is NULL, it can be set later with buf_setvnode().␊ |
| 614 | @return New buffer.␊ |
| 615 | */␊ |
| 616 | buf_t ␉buf_alloc(vnode_t);␊ |
| 617 | ␊ |
| 618 | /*!␊ |
| 619 | @function buf_free␊ |
| 620 | @abstract Free a buffer that was allocated with buf_alloc().␊ |
| 621 | @discussion The storage (UPL, data pointer) associated with an iobuf must be freed manually.␊ |
| 622 | @param bp The buffer to free.␊ |
| 623 | @return void.␊ |
| 624 | */␊ |
| 625 | void␉buf_free(buf_t);␊ |
| 626 | ␊ |
| 627 | /*␊ |
| 628 | * flags for buf_invalidateblks␊ |
| 629 | */␊ |
| 630 | #define␉BUF_WRITE_DATA␉0x0001␉␉/* write data blocks first */␊ |
| 631 | #define␉BUF_SKIP_META␉0x0002␉␉/* skip over metadata blocks */␊ |
| 632 | ␊ |
| 633 | /*!␊ |
| 634 | @function buf_invalidateblks␊ |
| 635 | @abstract Invalidate all the blocks associated with a vnode.␊ |
| 636 | @discussion This function does for all blocks associated with a vnode what buf_invalblkno does for one block.␊ |
| 637 | Again, it will only be able to invalidate data which were populated with traditional buffer cache routines,␊ |
| 638 | i.e. by buf_getblk() and callers thereof. Unlike buf_invalblkno(), it can be made to write dirty data to disk␊ |
| 639 | rather than casting it aside.␊ |
| 640 | @param bp The buffer whose data to invalidate.␊ |
| 641 | @param flags BUF_WRITE_DATA: write dirty data to disk with VNOP_BWRITE() before kicking buffer cache entries out.␊ |
| 642 | BUF_SKIP_META: do not invalidate metadata blocks.␊ |
| 643 | @param slpflag Flags to pass to "msleep" while waiting to acquire busy buffers. ␊ |
| 644 | @param slptimeo Timeout in "hz" (1/100 second) to wait for a buffer to become unbusy before waking from sleep␊ |
| 645 | and re-starting the scan.␊ |
| 646 | @return 0 for success, error values from msleep().␊ |
| 647 | */␊ |
| 648 | int␉buf_invalidateblks(vnode_t, int, int, int);␊ |
| 649 | ␊ |
| 650 | /*␊ |
| 651 | * flags for buf_flushdirtyblks and buf_iterate␊ |
| 652 | */␊ |
| 653 | #define BUF_SKIP_NONLOCKED␉0x01␊ |
| 654 | #define BUF_SKIP_LOCKED␉␉0x02␊ |
| 655 | #define BUF_SCAN_CLEAN␉␉0x04␉/* scan the clean buffers */␊ |
| 656 | #define BUF_SCAN_DIRTY␉␉0x08␉/* scan the dirty buffers */␊ |
| 657 | #define BUF_NOTIFY_BUSY␉␉0x10␉/* notify the caller about the busy pages during the scan */␊ |
| 658 | ␊ |
| 659 | ␊ |
| 660 | #define␉BUF_RETURNED␉␉0␊ |
| 661 | #define BUF_RETURNED_DONE␉1␊ |
| 662 | #define BUF_CLAIMED␉␉2␊ |
| 663 | #define␉BUF_CLAIMED_DONE␉3␊ |
| 664 | /*!␊ |
| 665 | @function buf_flushdirtyblks␊ |
| 666 | @abstract Write dirty file blocks to disk.␊ |
| 667 | @param vp The vnode whose blocks to flush.␊ |
| 668 | @param wait Wait for writes to complete before returning.␊ |
| 669 | @param flags Can pass zero, meaning "flush all dirty buffers." ␊ |
| 670 | BUF_SKIP_NONLOCKED: Skip buffers which are not busy when we encounter them.␊ |
| 671 | BUF_SKIP_LOCKED: Skip buffers which are busy when we encounter them.␊ |
| 672 | @param msg String to pass to msleep().␊ |
| 673 | @return void.␊ |
| 674 | */␊ |
| 675 | void␉buf_flushdirtyblks(vnode_t, int, int, const char *);␊ |
| 676 | ␊ |
| 677 | /*!␊ |
| 678 | @function buf_iterate␊ |
| 679 | @abstract Perform some operation on all buffers associated with a vnode.␊ |
| 680 | @param vp The vnode whose buffers to scan.␊ |
| 681 | @param callout Function to call on each buffer. Should return one of:␊ |
| 682 | BUF_RETURNED: buf_iterate() should call buf_brelse() on the buffer.␊ |
| 683 | BUF_RETURNED_DONE: buf_iterate() should call buf_brelse() on the buffer and then stop iterating.␊ |
| 684 | BUF_CLAIMED: buf_iterate() should continue iterating (and not call buf_brelse()).␊ |
| 685 | BUF_CLAIMED_DONE: buf_iterate() should stop iterating (and not call buf_brelse()).␊ |
| 686 | @param flag␊ |
| 687 | BUF_SKIP_NONLOCKED: Skip buffers which are not busy when we encounter them. BUF_SKIP_LOCKED: Skip buffers which are busy when we encounter them.␊ |
| 688 | BUF_SCAN_CLEAN: Call out on clean buffers.␊ |
| 689 | BUF_SCAN_DIRTY: Call out on dirty buffers.␊ |
| 690 | BUF_NOTIFY_BUSY: If a buffer cannot be acquired, pass a NULL buffer to callout; otherwise,␊ |
| 691 | that buffer will be silently skipped.␊ |
| 692 | @param arg Argument to pass to callout in addition to buffer.␊ |
| 693 | @return void.␊ |
| 694 | */␊ |
| 695 | void␉buf_iterate(vnode_t, int (*)(buf_t, void *), int, void *);␊ |
| 696 | ␊ |
| 697 | /*!␊ |
| 698 | @function buf_clear␊ |
| 699 | @abstract Zero out the storage associated with a buffer. ␊ |
| 700 | @discussion Calls buf_map() to get the buffer's data address; for a B_CLUSTER␊ |
| 701 | buffer (one which has had buf_setupl() called on it), it tries to map the buffer's␊ |
| 702 | UPL into memory; should only be called once during the life cycle of an iobuf (one allocated␊ |
| 703 | with buf_alloc()). ␊ |
| 704 | @param bp The buffer to zero out.␊ |
| 705 | @return void.␊ |
| 706 | */␊ |
| 707 | void␉buf_clear(buf_t);␊ |
| 708 | ␊ |
| 709 | /*!␊ |
| 710 | @function buf_bawrite␊ |
| 711 | @abstract Start an asychronous write on a buffer.␊ |
| 712 | @discussion Calls VNOP_BWRITE to start the process of propagating an asynchronous write down to the device layer.␊ |
| 713 | Callers can wait for writes to complete at their discretion using buf_biowait(). When this function is called,␊ |
| 714 | data should already have been written to the buffer's data region.␊ |
| 715 | @param bp The buffer on which to initiate I/O.␊ |
| 716 | @param throttle If "throttle" is nonzero and more than VNODE_ASYNC_THROTTLE writes are in progress on this file,␊ |
| 717 | buf_bawrite() will block until the write count drops below VNODE_ASYNC_THROTTLE. If "throttle" is zero and the write␊ |
| 718 | count is high, it will fail with EWOULDBLOCK; the caller can decide whether to make a blocking call or pursue␊ |
| 719 | other opportunities.␊ |
| 720 | @return EWOULDBLOCK if write count is high and "throttle" is zero; otherwise, errors from VNOP_BWRITE.␊ |
| 721 | */␊ |
| 722 | errno_t␉buf_bawrite(buf_t);␊ |
| 723 | ␊ |
| 724 | /*!␊ |
| 725 | @function buf_bdwrite␊ |
| 726 | @abstract Mark a buffer for delayed write.␊ |
| 727 | @discussion Marks a buffer as waiting for delayed write and the current I/O as complete; data will be written to backing store␊ |
| 728 | before the buffer is reused, but it will not be queued for I/O immediately. Note that for buffers allocated␊ |
| 729 | with buf_alloc(), there are no such guarantees; you must take care of your own flushing to disk. If␊ |
| 730 | the number of delayed writes pending on the system is greater than an internal limit and the caller has not␊ |
| 731 | requested otherwise [see return_error] , buf_bdwrite() will unilaterally launch an asynchronous I/O with buf_bawrite() to keep the pile of␊ |
| 732 | delayed writes from getting too large.␊ |
| 733 | @param bp The buffer to mark for delayed write.␊ |
| 734 | @param return_error If the number of pending delayed writes systemwide is larger than an internal limit,␊ |
| 735 | return EAGAIN rather than doing an asynchronous write.␊ |
| 736 | @return EAGAIN for return_error != 0 case, 0 for succeess, errors from buf_bawrite.␊ |
| 737 | */␊ |
| 738 | errno_t␉buf_bdwrite(buf_t);␊ |
| 739 | ␊ |
| 740 | /*!␊ |
| 741 | @function buf_bwrite␊ |
| 742 | @abstract Write a buffer's data to backing store.␊ |
| 743 | @discussion Once the data in a buffer has been modified, buf_bwrite() starts sending it to disk by calling␊ |
| 744 | VNOP_STRATEGY. Unless B_ASYNC has been set on the buffer (by buf_setflags() or otherwise), data will have ␊ |
| 745 | been written to disk when buf_bwrite() returns. See Bach (p 56).␊ |
| 746 | @param bp The buffer to write to disk.␊ |
| 747 | @return 0 for success; errors from buf_biowait().␊ |
| 748 | */␊ |
| 749 | errno_t␉buf_bwrite(buf_t);␊ |
| 750 | ␊ |
| 751 | /*!␊ |
| 752 | @function buf_biodone␊ |
| 753 | @abstract Mark an I/O as completed.␊ |
| 754 | @discussion buf_biodone() should be called by whosoever decides that an I/O on a buffer is complete; for example,␊ |
| 755 | IOStorageFamily. It clears the dirty flag on a buffer and signals on the vnode that a write has completed␊ |
| 756 | with vnode_writedone(). If a callout or filter has been set on the buffer, that function is called. In the case␊ |
| 757 | of a callout, that function is expected to take care of cleaning up and freeing the buffer.␊ |
| 758 | Otherwise, if the buffer is marked B_ASYNC (e.g. it was passed to buf_bawrite()), then buf_biodone()␊ |
| 759 | considers itself justified in calling buf_brelse() to return it to free lists--no one is waiting for it. Finally, ␊ |
| 760 | waiters on the bp (e.g. in buf_biowait()) are woken up.␊ |
| 761 | @param bp The buffer to mark as done with I/O.␊ |
| 762 | @return void.␊ |
| 763 | */␊ |
| 764 | void␉buf_biodone(buf_t);␊ |
| 765 | ␊ |
| 766 | /*!␊ |
| 767 | @function buf_biowait␊ |
| 768 | @abstract Wait for I/O on a buffer to complete.␊ |
| 769 | @discussion Waits for I/O on a buffer to finish, as marked by a buf_biodone() call. ␊ |
| 770 | @param bp The buffer to wait on.␊ |
| 771 | @return 0 for a successful wait; nonzero the buffer has been marked as EINTR or had an error set on it.␊ |
| 772 | */␊ |
| 773 | errno_t␉buf_biowait(buf_t);␊ |
| 774 | ␊ |
| 775 | /*!␊ |
| 776 | @function buf_brelse␊ |
| 777 | @abstract Release any claim to a buffer, sending it back to free lists.␊ |
| 778 | @discussion buf_brelse() cleans up buffer state and releases a buffer to the free lists. If the buffer␊ |
| 779 | is not marked invalid and its pages are dirty (e.g. a delayed write was made), its data will be commited␊ |
| 780 | to backing store. If it is marked invalid, its data will be discarded completely. ␊ |
| 781 | A valid, cacheable buffer will be put on a list and kept in the buffer hash so it␊ |
| 782 | can be found again; otherwise, it will be dissociated from its vnode and treated as empty. Which list a valid␊ |
| 783 | buffer is placed on depends on the use of buf_markaged(), whether it is metadata, and the B_LOCKED flag. A␊ |
| 784 | B_LOCKED buffer will not be available for reuse by other files, though its data may be paged out.␊ |
| 785 | Note that buf_brelse() is intended for use with traditionally allocated buffers.␊ |
| 786 | @param bp The buffer to release.␊ |
| 787 | @retrn void.␊ |
| 788 | */␊ |
| 789 | void␉buf_brelse(buf_t);␊ |
| 790 | ␊ |
| 791 | /*!␊ |
| 792 | @function minphys␊ |
| 793 | @abstract Adjust a buffer's count to be no more than maximum physical I/O transfer size for the host architecture.␊ |
| 794 | @discussion physio() takes as a parameter a function to bound transfer sizes for each VNOP_STRATEGY() call. minphys()␊ |
| 795 | is a default implementation. It calls buf_setcount() to make the buffer's count the min() of its current count␊ |
| 796 | and the max I/O size for the host architecture.␊ |
| 797 | @param bp The buffer whose byte count to modify.␊ |
| 798 | @return New byte count.␊ |
| 799 | */␊ |
| 800 | u_int␉minphys(buf_t bp);␊ |
| 801 | ␊ |
| 802 | /*␊ |
| 803 | * Flags for operation type in getblk()␊ |
| 804 | */␊ |
| 805 | #define␉BLK_READ␉0x01␉/* buffer for read */␊ |
| 806 | #define␉BLK_WRITE␉0x02␉/* buffer for write */␊ |
| 807 | #define␉BLK_META␉0x10␉/* buffer for metadata */␊ |
| 808 | /*␊ |
| 809 | * modifier for above flags... if set, getblk will only return␊ |
| 810 | * a bp that is already valid... i.e. found in the cache␊ |
| 811 | */␊ |
| 812 | #define BLK_ONLYVALID␉0x80000000␊ |
| 813 | ␊ |
| 814 | /*!␊ |
| 815 | @function buf_getblk␊ |
| 816 | @abstract Traditional buffer cache routine to get a buffer corresponding to a logical block in a file.␊ |
| 817 | @discussion buf_getblk() gets a buffer, not necessarily containing valid data, representing a block in a file. ␊ |
| 818 | A metadata buffer will be returned with its own zone-allocated storage, managed by the traditional buffer-cache␊ |
| 819 | layer, whereas data buffers will be returned hooked into backing by the UBC (which in fact controls the caching of data).␊ |
| 820 | buf_getblk() first looks for the buffer header in cache; if the buffer is in-core but busy, buf_getblk() will wait for it to become␊ |
| 821 | unbusy, depending on the slpflag and slptimeo parameters. If the buffer is found unbusy and is a metadata buffer,␊ |
| 822 | it must already contain valid data and will be returned directly; data buffers will have a UPL configured to␊ |
| 823 | prepare for interaction with the underlying UBC. If the buffer is found in core, it will be marked as such␊ |
| 824 | and buf_fromcache() will return truth. A buffer is allocated and initialized (but not filled with data)␊ |
| 825 | if none is found in core. buf_bread(), buf_breadn(), buf_meta_bread(), and buf_meta_breadn() all ␊ |
| 826 | return buffers obtained with buf_getblk().␊ |
| 827 | @param vp File for which to get block.␊ |
| 828 | @param blkno Logical block number.␊ |
| 829 | @param size Size of block.␊ |
| 830 | @param slpflag Flag to pass to msleep() while waiting for buffer to become unbusy.␊ |
| 831 | @param slptimeo Time, in milliseconds, to wait for buffer to become unbusy. 0 means to wait indefinitely.␊ |
| 832 | @param operation BLK_READ: want a read buffer. BLK_WRITE: want a write buffer. BLK_META: want a metadata buffer. BLK_ONLYVALID: ␊ |
| 833 | only return buffers which are found in core (do not allocate anew), and do not change buffer size. The last remark means␊ |
| 834 | that if a given logical block is found in core with a different size than what is requested, the buffer size will not be modified.␊ |
| 835 | @return Buffer found in core or newly allocated, either containing valid data or ready for I/O.␊ |
| 836 | */␊ |
| 837 | buf_t␉buf_getblk(vnode_t, daddr64_t, int, int, int, int);␊ |
| 838 | ␊ |
| 839 | /*!␊ |
| 840 | @function buf_geteblk␊ |
| 841 | @abstract Get a metadata buffer which is marked invalid and not associated with any vnode.␊ |
| 842 | @discussion A buffer is returned with zone-allocated storage of the specified size, marked B_META and invalid. ␊ |
| 843 | It has no vnode and is not visible in the buffer hash. ␊ |
| 844 | @param size Size of buffer.␊ |
| 845 | @return Always returns a new buffer.␊ |
| 846 | */␊ |
| 847 | buf_t␉buf_geteblk(int);␊ |
| 848 | ␊ |
| 849 | ␊ |
| 850 | __END_DECLS␊ |
| 851 | ␊ |
| 852 | ␊ |
| 853 | /* Macros to clear/set/test flags. */␊ |
| 854 | #define␉SET(t, f)␉(t) |= (f)␊ |
| 855 | #define␉CLR(t, f)␉(t) &= ~(f)␊ |
| 856 | #define␉ISSET(t, f)␉((t) & (f))␊ |
| 857 | ␊ |
| 858 | ␊ |
| 859 | #endif /* !_SYS_BUF_H_ */␊ |
| 860 | |
