Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/ufs/ffs/ffs_rawread.c
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1 /*- 2 * Copyright (c) 2000-2003 Tor Egge 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD: releng/8.0/sys/ufs/ffs/ffs_rawread.c 177493 2008-03-22 09:15:16Z jeff $"); 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/fcntl.h> 33 #include <sys/file.h> 34 #include <sys/stat.h> 35 #include <sys/proc.h> 36 #include <sys/limits.h> 37 #include <sys/mount.h> 38 #include <sys/namei.h> 39 #include <sys/vnode.h> 40 #include <sys/conf.h> 41 #include <sys/filio.h> 42 #include <sys/ttycom.h> 43 #include <sys/bio.h> 44 #include <sys/buf.h> 45 #include <ufs/ufs/extattr.h> 46 #include <ufs/ufs/quota.h> 47 #include <ufs/ufs/inode.h> 48 #include <ufs/ufs/ufsmount.h> 49 #include <ufs/ufs/ufs_extern.h> 50 #include <ufs/ffs/fs.h> 51 #include <ufs/ffs/ffs_extern.h> 52 53 #include <vm/vm.h> 54 #include <vm/vm_extern.h> 55 #include <vm/vm_object.h> 56 #include <sys/kernel.h> 57 #include <sys/sysctl.h> 58 59 static int ffs_rawread_readahead(struct vnode *vp, 60 caddr_t udata, 61 off_t offset, 62 size_t len, 63 struct thread *td, 64 struct buf *bp, 65 caddr_t sa); 66 static int ffs_rawread_main(struct vnode *vp, 67 struct uio *uio); 68 69 static int ffs_rawread_sync(struct vnode *vp); 70 71 int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone); 72 73 void ffs_rawread_setup(void); 74 75 SYSCTL_DECL(_vfs_ffs); 76 77 static int ffsrawbufcnt = 4; 78 SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0, 79 "Buffers available for raw reads"); 80 81 static int allowrawread = 1; 82 SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0, 83 "Flag to enable raw reads"); 84 85 static int rawreadahead = 1; 86 SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0, 87 "Flag to enable readahead for long raw reads"); 88 89 90 void 91 ffs_rawread_setup(void) 92 { 93 ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8; 94 } 95 96 97 static int 98 ffs_rawread_sync(struct vnode *vp) 99 { 100 int error; 101 int upgraded; 102 struct bufobj *bo; 103 struct mount *mp; 104 105 /* Check for dirty mmap, pending writes and dirty buffers */ 106 bo = &vp->v_bufobj; 107 BO_LOCK(bo); 108 VI_LOCK(vp); 109 if (bo->bo_numoutput > 0 || 110 bo->bo_dirty.bv_cnt > 0 || 111 (vp->v_iflag & VI_OBJDIRTY) != 0) { 112 VI_UNLOCK(vp); 113 BO_UNLOCK(bo); 114 115 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 116 if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) 117 upgraded = 1; 118 else 119 upgraded = 0; 120 VOP_UNLOCK(vp, 0); 121 (void) vn_start_write(vp, &mp, V_WAIT); 122 VOP_LOCK(vp, LK_EXCLUSIVE); 123 } else if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) { 124 upgraded = 1; 125 /* Upgrade to exclusive lock, this might block */ 126 VOP_LOCK(vp, LK_UPGRADE); 127 } else 128 upgraded = 0; 129 130 131 VI_LOCK(vp); 132 /* Check if vnode was reclaimed while unlocked. */ 133 if ((vp->v_iflag & VI_DOOMED) != 0) { 134 VI_UNLOCK(vp); 135 if (upgraded != 0) 136 VOP_LOCK(vp, LK_DOWNGRADE); 137 vn_finished_write(mp); 138 return (EIO); 139 } 140 /* Attempt to msync mmap() regions to clean dirty mmap */ 141 if ((vp->v_iflag & VI_OBJDIRTY) != 0) { 142 VI_UNLOCK(vp); 143 if (vp->v_object != NULL) { 144 VM_OBJECT_LOCK(vp->v_object); 145 vm_object_page_clean(vp->v_object, 0, 0, OBJPC_SYNC); 146 VM_OBJECT_UNLOCK(vp->v_object); 147 } 148 } else 149 VI_UNLOCK(vp); 150 151 /* Wait for pending writes to complete */ 152 BO_LOCK(bo); 153 error = bufobj_wwait(&vp->v_bufobj, 0, 0); 154 if (error != 0) { 155 /* XXX: can't happen with a zero timeout ??? */ 156 BO_UNLOCK(bo); 157 if (upgraded != 0) 158 VOP_LOCK(vp, LK_DOWNGRADE); 159 vn_finished_write(mp); 160 return (error); 161 } 162 /* Flush dirty buffers */ 163 if (bo->bo_dirty.bv_cnt > 0) { 164 BO_UNLOCK(bo); 165 if ((error = ffs_syncvnode(vp, MNT_WAIT)) != 0) { 166 if (upgraded != 0) 167 VOP_LOCK(vp, LK_DOWNGRADE); 168 vn_finished_write(mp); 169 return (error); 170 } 171 BO_LOCK(bo); 172 if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0) 173 panic("ffs_rawread_sync: dirty bufs"); 174 } 175 BO_UNLOCK(bo); 176 if (upgraded != 0) 177 VOP_LOCK(vp, LK_DOWNGRADE); 178 vn_finished_write(mp); 179 } else { 180 VI_UNLOCK(vp); 181 BO_UNLOCK(bo); 182 } 183 return 0; 184 } 185 186 187 static int 188 ffs_rawread_readahead(struct vnode *vp, 189 caddr_t udata, 190 off_t offset, 191 size_t len, 192 struct thread *td, 193 struct buf *bp, 194 caddr_t sa) 195 { 196 int error; 197 u_int iolen; 198 off_t blockno; 199 int blockoff; 200 int bsize; 201 struct vnode *dp; 202 int bforwards; 203 struct inode *ip; 204 ufs2_daddr_t blkno; 205 206 bsize = vp->v_mount->mnt_stat.f_iosize; 207 208 ip = VTOI(vp); 209 dp = ip->i_devvp; 210 211 iolen = ((vm_offset_t) udata) & PAGE_MASK; 212 bp->b_bcount = len; 213 if (bp->b_bcount + iolen > bp->b_kvasize) { 214 bp->b_bcount = bp->b_kvasize; 215 if (iolen != 0) 216 bp->b_bcount -= PAGE_SIZE; 217 } 218 bp->b_flags = 0; /* XXX necessary ? */ 219 bp->b_iocmd = BIO_READ; 220 bp->b_iodone = bdone; 221 bp->b_data = udata; 222 bp->b_saveaddr = sa; 223 blockno = offset / bsize; 224 blockoff = (offset % bsize) / DEV_BSIZE; 225 if ((daddr_t) blockno != blockno) { 226 return EINVAL; /* blockno overflow */ 227 } 228 229 bp->b_lblkno = bp->b_blkno = blockno; 230 231 error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL); 232 if (error != 0) 233 return error; 234 if (blkno == -1) { 235 236 /* Fill holes with NULs to preserve semantics */ 237 238 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize) 239 bp->b_bcount = bsize - blockoff * DEV_BSIZE; 240 bp->b_bufsize = bp->b_bcount; 241 242 if (vmapbuf(bp) < 0) 243 return EFAULT; 244 245 if (ticks - PCPU_GET(switchticks) >= hogticks) 246 uio_yield(); 247 bzero(bp->b_data, bp->b_bufsize); 248 249 /* Mark operation completed (similar to bufdone()) */ 250 251 bp->b_resid = 0; 252 bp->b_flags |= B_DONE; 253 return 0; 254 } 255 bp->b_blkno = blkno + blockoff; 256 bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE; 257 258 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards)) 259 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE; 260 bp->b_bufsize = bp->b_bcount; 261 262 if (vmapbuf(bp) < 0) 263 return EFAULT; 264 265 BO_STRATEGY(&dp->v_bufobj, bp); 266 return 0; 267 } 268 269 270 static int 271 ffs_rawread_main(struct vnode *vp, 272 struct uio *uio) 273 { 274 int error, nerror; 275 struct buf *bp, *nbp, *tbp; 276 caddr_t sa, nsa, tsa; 277 u_int iolen; 278 int spl; 279 caddr_t udata; 280 long resid; 281 off_t offset; 282 struct thread *td; 283 284 td = uio->uio_td ? uio->uio_td : curthread; 285 udata = uio->uio_iov->iov_base; 286 resid = uio->uio_resid; 287 offset = uio->uio_offset; 288 289 /* 290 * keep the process from being swapped 291 */ 292 PHOLD(td->td_proc); 293 294 error = 0; 295 nerror = 0; 296 297 bp = NULL; 298 nbp = NULL; 299 sa = NULL; 300 nsa = NULL; 301 302 while (resid > 0) { 303 304 if (bp == NULL) { /* Setup first read */ 305 /* XXX: Leave some bufs for swap */ 306 bp = getpbuf(&ffsrawbufcnt); 307 sa = bp->b_data; 308 pbgetvp(vp, bp); 309 error = ffs_rawread_readahead(vp, udata, offset, 310 resid, td, bp, sa); 311 if (error != 0) 312 break; 313 314 if (resid > bp->b_bufsize) { /* Setup fist readahead */ 315 /* XXX: Leave bufs for swap */ 316 if (rawreadahead != 0) 317 nbp = trypbuf(&ffsrawbufcnt); 318 else 319 nbp = NULL; 320 if (nbp != NULL) { 321 nsa = nbp->b_data; 322 pbgetvp(vp, nbp); 323 324 nerror = ffs_rawread_readahead(vp, 325 udata + 326 bp->b_bufsize, 327 offset + 328 bp->b_bufsize, 329 resid - 330 bp->b_bufsize, 331 td, 332 nbp, 333 nsa); 334 if (nerror) { 335 pbrelvp(nbp); 336 relpbuf(nbp, &ffsrawbufcnt); 337 nbp = NULL; 338 } 339 } 340 } 341 } 342 343 spl = splbio(); 344 bwait(bp, PRIBIO, "rawrd"); 345 splx(spl); 346 347 vunmapbuf(bp); 348 349 iolen = bp->b_bcount - bp->b_resid; 350 if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) { 351 nerror = 0; /* Ignore possible beyond EOF error */ 352 break; /* EOF */ 353 } 354 355 if ((bp->b_ioflags & BIO_ERROR) != 0) { 356 error = bp->b_error; 357 break; 358 } 359 resid -= iolen; 360 udata += iolen; 361 offset += iolen; 362 if (iolen < bp->b_bufsize) { 363 /* Incomplete read. Try to read remaining part */ 364 error = ffs_rawread_readahead(vp, 365 udata, 366 offset, 367 bp->b_bufsize - iolen, 368 td, 369 bp, 370 sa); 371 if (error != 0) 372 break; 373 } else if (nbp != NULL) { /* Complete read with readahead */ 374 375 tbp = bp; 376 bp = nbp; 377 nbp = tbp; 378 379 tsa = sa; 380 sa = nsa; 381 nsa = tsa; 382 383 if (resid <= bp->b_bufsize) { /* No more readaheads */ 384 pbrelvp(nbp); 385 relpbuf(nbp, &ffsrawbufcnt); 386 nbp = NULL; 387 } else { /* Setup next readahead */ 388 nerror = ffs_rawread_readahead(vp, 389 udata + 390 bp->b_bufsize, 391 offset + 392 bp->b_bufsize, 393 resid - 394 bp->b_bufsize, 395 td, 396 nbp, 397 nsa); 398 if (nerror != 0) { 399 pbrelvp(nbp); 400 relpbuf(nbp, &ffsrawbufcnt); 401 nbp = NULL; 402 } 403 } 404 } else if (nerror != 0) {/* Deferred Readahead error */ 405 break; 406 } else if (resid > 0) { /* More to read, no readahead */ 407 error = ffs_rawread_readahead(vp, udata, offset, 408 resid, td, bp, sa); 409 if (error != 0) 410 break; 411 } 412 } 413 414 if (bp != NULL) { 415 pbrelvp(bp); 416 relpbuf(bp, &ffsrawbufcnt); 417 } 418 if (nbp != NULL) { /* Run down readahead buffer */ 419 spl = splbio(); 420 bwait(nbp, PRIBIO, "rawrd"); 421 splx(spl); 422 vunmapbuf(nbp); 423 pbrelvp(nbp); 424 relpbuf(nbp, &ffsrawbufcnt); 425 } 426 427 if (error == 0) 428 error = nerror; 429 PRELE(td->td_proc); 430 uio->uio_iov->iov_base = udata; 431 uio->uio_resid = resid; 432 uio->uio_offset = offset; 433 return error; 434 } 435 436 437 int 438 ffs_rawread(struct vnode *vp, 439 struct uio *uio, 440 int *workdone) 441 { 442 if (allowrawread != 0 && 443 uio->uio_iovcnt == 1 && 444 uio->uio_segflg == UIO_USERSPACE && 445 uio->uio_resid == uio->uio_iov->iov_len && 446 (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags & 447 TDP_DEADLKTREAT) == 0) { 448 int secsize; /* Media sector size */ 449 off_t filebytes; /* Bytes left of file */ 450 int blockbytes; /* Bytes left of file in full blocks */ 451 int partialbytes; /* Bytes in last partial block */ 452 int skipbytes; /* Bytes not to read in ffs_rawread */ 453 struct inode *ip; 454 int error; 455 456 457 /* Only handle sector aligned reads */ 458 ip = VTOI(vp); 459 secsize = ip->i_devvp->v_bufobj.bo_bsize; 460 if ((uio->uio_offset & (secsize - 1)) == 0 && 461 (uio->uio_resid & (secsize - 1)) == 0) { 462 463 /* Sync dirty pages and buffers if needed */ 464 error = ffs_rawread_sync(vp); 465 if (error != 0) 466 return error; 467 468 /* Check for end of file */ 469 if (ip->i_size > uio->uio_offset) { 470 filebytes = ip->i_size - uio->uio_offset; 471 472 /* No special eof handling needed ? */ 473 if (uio->uio_resid <= filebytes) { 474 *workdone = 1; 475 return ffs_rawread_main(vp, uio); 476 } 477 478 partialbytes = ((unsigned int) ip->i_size) % 479 ip->i_fs->fs_bsize; 480 blockbytes = (int) filebytes - partialbytes; 481 if (blockbytes > 0) { 482 skipbytes = uio->uio_resid - 483 blockbytes; 484 uio->uio_resid = blockbytes; 485 error = ffs_rawread_main(vp, uio); 486 uio->uio_resid += skipbytes; 487 if (error != 0) 488 return error; 489 /* Read remaining part using buffer */ 490 } 491 } 492 } 493 } 494 *workdone = 0; 495 return 0; 496 }
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