sys/ufs/ffs/ffs_rawread.c

   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("$FreeBSD$");
  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, struct thread *td);
  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, struct thread *td)
  99 {
 100         int spl;
 101         int error;
 102         int upgraded;
 103         struct bufobj *bo;
 104         struct mount *mp;
 105
 106         /* Check for dirty mmap, pending writes and dirty buffers */
 107         spl = splbio();
 108         VI_LOCK(vp);
 109         bo = &vp->v_bufobj;
 110         if (bo->bo_numoutput > 0 ||
 111             bo->bo_dirty.bv_cnt > 0 ||
 112             (vp->v_iflag & VI_OBJDIRTY) != 0) {
 113                 splx(spl);
 114                 VI_UNLOCK(vp);
 115
 116                 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 117                         if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE)
 118                                 upgraded = 1;
 119                         else
 120                                 upgraded = 0;
 121                         VOP_UNLOCK(vp, 0, td);
 122                         (void) vn_start_write(vp, &mp, V_WAIT);
 123                         VOP_LOCK(vp, LK_EXCLUSIVE, td);
 124                 } else if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE) {
 125                         upgraded = 1;
 126                         /* Upgrade to exclusive lock, this might block */
 127                         VOP_LOCK(vp, LK_UPGRADE, td);
 128                 } else
 129                         upgraded = 0;
 130
 131
 132                 VI_LOCK(vp);
 133                 /* Check if vnode was reclaimed while unlocked. */
 134                 if ((vp->v_iflag & VI_DOOMED) != 0) {
 135                         VI_UNLOCK(vp);
 136                         if (upgraded != 0)
 137                                 VOP_LOCK(vp, LK_DOWNGRADE, td);
 138                         vn_finished_write(mp);
 139                         return (EIO);
 140                 }
 141                 /* Attempt to msync mmap() regions to clean dirty mmap */
 142                 if ((vp->v_iflag & VI_OBJDIRTY) != 0) {
 143                         VI_UNLOCK(vp);
 144                         if (vp->v_object != NULL) {
 145                                 VM_OBJECT_LOCK(vp->v_object);
 146                                 vm_object_page_clean(vp->v_object, 0, 0, OBJPC_SYNC);
 147                                 VM_OBJECT_UNLOCK(vp->v_object);
 148                         }
 149                         VI_LOCK(vp);
 150                 }
 151
 152                 /* Wait for pending writes to complete */
 153                 spl = splbio();
 154                 error = bufobj_wwait(&vp->v_bufobj, 0, 0);
 155                 if (error != 0) {
 156                         /* XXX: can't happen with a zero timeout ??? */
 157                         splx(spl);
 158                         VI_UNLOCK(vp);
 159                         if (upgraded != 0)
 160                                 VOP_LOCK(vp, LK_DOWNGRADE, td);
 161                         vn_finished_write(mp);
 162                         return (error);
 163                 }
 164                 /* Flush dirty buffers */
 165                 if (bo->bo_dirty.bv_cnt > 0) {
 166                         splx(spl);
 167                         VI_UNLOCK(vp);
 168                         if ((error = ffs_syncvnode(vp, MNT_WAIT)) != 0) {
 169                                 if (upgraded != 0)
 170                                         VOP_LOCK(vp, LK_DOWNGRADE, td);
 171                                 vn_finished_write(mp);
 172                                 return (error);
 173                         }
 174                         VI_LOCK(vp);
 175                         spl = splbio();
 176                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 177                                 panic("ffs_rawread_sync: dirty bufs");
 178                 }
 179                 splx(spl);
 180                 VI_UNLOCK(vp);
 181                 if (upgraded != 0)
 182                         VOP_LOCK(vp, LK_DOWNGRADE, td);
 183                 vn_finished_write(mp);
 184         } else {
 185                 splx(spl);
 186                 VI_UNLOCK(vp);
 187         }
 188         return 0;
 189 }
 190
 191
 192 static int
 193 ffs_rawread_readahead(struct vnode *vp,
 194                       caddr_t udata,
 195                       off_t offset,
 196                       size_t len,
 197                       struct thread *td,
 198                       struct buf *bp,
 199                       caddr_t sa)
 200 {
 201         int error;
 202         u_int iolen;
 203         off_t blockno;
 204         int blockoff;
 205         int bsize;
 206         struct vnode *dp;
 207         int bforwards;
 208         struct inode *ip;
 209         ufs2_daddr_t blkno;
 210
 211         bsize = vp->v_mount->mnt_stat.f_iosize;
 212
 213         ip = VTOI(vp);
 214         dp = ip->i_devvp;
 215
 216         iolen = ((vm_offset_t) udata) & PAGE_MASK;
 217         bp->b_bcount = len;
 218         if (bp->b_bcount + iolen > bp->b_kvasize) {
 219                 bp->b_bcount = bp->b_kvasize;
 220                 if (iolen != 0)
 221                         bp->b_bcount -= PAGE_SIZE;
 222         }
 223         bp->b_flags = 0;        /* XXX necessary ? */
 224         bp->b_iocmd = BIO_READ;
 225         bp->b_iodone = bdone;
 226         bp->b_data = udata;
 227         bp->b_saveaddr = sa;
 228         blockno = offset / bsize;
 229         blockoff = (offset % bsize) / DEV_BSIZE;
 230         if ((daddr_t) blockno != blockno) {
 231                 return EINVAL; /* blockno overflow */
 232         }
 233
 234         bp->b_lblkno = bp->b_blkno = blockno;
 235
 236         error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL);
 237         if (error != 0)
 238                 return error;
 239         if (blkno == -1) {
 240
 241                 /* Fill holes with NULs to preserve semantics */
 242
 243                 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
 244                         bp->b_bcount = bsize - blockoff * DEV_BSIZE;
 245                 bp->b_bufsize = bp->b_bcount;
 246
 247                 if (vmapbuf(bp) < 0)
 248                         return EFAULT;
 249
 250                 if (ticks - PCPU_GET(switchticks) >= hogticks)
 251                         uio_yield();
 252                 bzero(bp->b_data, bp->b_bufsize);
 253
 254                 /* Mark operation completed (similar to bufdone()) */
 255
 256                 bp->b_resid = 0;
 257                 bp->b_flags |= B_DONE;
 258                 return 0;
 259         }
 260         bp->b_blkno = blkno + blockoff;
 261         bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE;
 262
 263         if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
 264                 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
 265         bp->b_bufsize = bp->b_bcount;
 266
 267         if (vmapbuf(bp) < 0)
 268                 return EFAULT;
 269
 270         BO_STRATEGY(&dp->v_bufobj, bp);
 271         return 0;
 272 }
 273
 274
 275 static int
 276 ffs_rawread_main(struct vnode *vp,
 277                  struct uio *uio)
 278 {
 279         int error, nerror;
 280         struct buf *bp, *nbp, *tbp;
 281         caddr_t sa, nsa, tsa;
 282         u_int iolen;
 283         int spl;
 284         caddr_t udata;
 285         long resid;
 286         off_t offset;
 287         struct thread *td;
 288
 289         td = uio->uio_td ? uio->uio_td : curthread;
 290         udata = uio->uio_iov->iov_base;
 291         resid = uio->uio_resid;
 292         offset = uio->uio_offset;
 293
 294         /*
 295          * keep the process from being swapped
 296          */
 297         PHOLD(td->td_proc);
 298
 299         error = 0;
 300         nerror = 0;
 301
 302         bp = NULL;
 303         nbp = NULL;
 304         sa = NULL;
 305         nsa = NULL;
 306
 307         while (resid > 0) {
 308
 309                 if (bp == NULL) { /* Setup first read */
 310                         /* XXX: Leave some bufs for swap */
 311                         bp = getpbuf(&ffsrawbufcnt);
 312                         sa = bp->b_data;
 313                         pbgetvp(vp, bp);
 314                         error = ffs_rawread_readahead(vp, udata, offset,
 315                                                      resid, td, bp, sa);
 316                         if (error != 0)
 317                                 break;
 318
 319                         if (resid > bp->b_bufsize) { /* Setup fist readahead */
 320                                 /* XXX: Leave bufs for swap */
 321                                 if (rawreadahead != 0)
 322                                         nbp = trypbuf(&ffsrawbufcnt);
 323                                 else
 324                                         nbp = NULL;
 325                                 if (nbp != NULL) {
 326                                         nsa = nbp->b_data;
 327                                         pbgetvp(vp, nbp);
 328
 329                                         nerror = ffs_rawread_readahead(vp,
 330                                                                        udata +
 331                                                                        bp->b_bufsize,
 332                                                                        offset +
 333                                                                        bp->b_bufsize,
 334                                                                        resid -
 335                                                                        bp->b_bufsize,
 336                                                                        td,
 337                                                                        nbp,
 338                                                                        nsa);
 339                                         if (nerror) {
 340                                                 pbrelvp(nbp);
 341                                                 relpbuf(nbp, &ffsrawbufcnt);
 342                                                 nbp = NULL;
 343                                         }
 344                                 }
 345                         }
 346                 }
 347
 348                 spl = splbio();
 349                 bwait(bp, PRIBIO, "rawrd");
 350                 splx(spl);
 351
 352                 vunmapbuf(bp);
 353
 354                 iolen = bp->b_bcount - bp->b_resid;
 355                 if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
 356                         nerror = 0;     /* Ignore possible beyond EOF error */
 357                         break; /* EOF */
 358                 }
 359
 360                 if ((bp->b_ioflags & BIO_ERROR) != 0) {
 361                         error = bp->b_error;
 362                         break;
 363                 }
 364                 resid -= iolen;
 365                 udata += iolen;
 366                 offset += iolen;
 367                 if (iolen < bp->b_bufsize) {
 368                         /* Incomplete read.  Try to read remaining part */
 369                         error = ffs_rawread_readahead(vp,
 370                                                       udata,
 371                                                       offset,
 372                                                       bp->b_bufsize - iolen,
 373                                                       td,
 374                                                       bp,
 375                                                       sa);
 376                         if (error != 0)
 377                                 break;
 378                 } else if (nbp != NULL) { /* Complete read with readahead */
 379
 380                         tbp = bp;
 381                         bp = nbp;
 382                         nbp = tbp;
 383
 384                         tsa = sa;
 385                         sa = nsa;
 386                         nsa = tsa;
 387
 388                         if (resid <= bp->b_bufsize) { /* No more readaheads */
 389                                 pbrelvp(nbp);
 390                                 relpbuf(nbp, &ffsrawbufcnt);
 391                                 nbp = NULL;
 392                         } else { /* Setup next readahead */
 393                                 nerror = ffs_rawread_readahead(vp,
 394                                                                udata +
 395                                                                bp->b_bufsize,
 396                                                                offset +
 397                                                                bp->b_bufsize,
 398                                                                resid -
 399                                                                bp->b_bufsize,
 400                                                                td,
 401                                                                nbp,
 402                                                                nsa);
 403                                 if (nerror != 0) {
 404                                         pbrelvp(nbp);
 405                                         relpbuf(nbp, &ffsrawbufcnt);
 406                                         nbp = NULL;
 407                                 }
 408                         }
 409                 } else if (nerror != 0) {/* Deferred Readahead error */
 410                         break;
 411                 }  else if (resid > 0) { /* More to read, no readahead */
 412                         error = ffs_rawread_readahead(vp, udata, offset,
 413                                                       resid, td, bp, sa);
 414                         if (error != 0)
 415                                 break;
 416                 }
 417         }
 418
 419         if (bp != NULL) {
 420                 pbrelvp(bp);
 421                 relpbuf(bp, &ffsrawbufcnt);
 422         }
 423         if (nbp != NULL) {                      /* Run down readahead buffer */
 424                 spl = splbio();
 425                 bwait(nbp, PRIBIO, "rawrd");
 426                 splx(spl);
 427                 vunmapbuf(nbp);
 428                 pbrelvp(nbp);
 429                 relpbuf(nbp, &ffsrawbufcnt);
 430         }
 431
 432         if (error == 0)
 433                 error = nerror;
 434         PRELE(td->td_proc);
 435         uio->uio_iov->iov_base = udata;
 436         uio->uio_resid = resid;
 437         uio->uio_offset = offset;
 438         return error;
 439 }
 440
 441
 442 int
 443 ffs_rawread(struct vnode *vp,
 444             struct uio *uio,
 445             int *workdone)
 446 {
 447         if (allowrawread != 0 &&
 448             uio->uio_iovcnt == 1 &&
 449             uio->uio_segflg == UIO_USERSPACE &&
 450             uio->uio_resid == uio->uio_iov->iov_len &&
 451             (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags &
 452              TDP_DEADLKTREAT) == 0) {
 453                 int secsize;            /* Media sector size */
 454                 off_t filebytes;        /* Bytes left of file */
 455                 int blockbytes;         /* Bytes left of file in full blocks */
 456                 int partialbytes;       /* Bytes in last partial block */
 457                 int skipbytes;          /* Bytes not to read in ffs_rawread */
 458                 struct inode *ip;
 459                 int error;
 460
 461
 462                 /* Only handle sector aligned reads */
 463                 ip = VTOI(vp);
 464                 secsize = ip->i_devvp->v_bufobj.bo_bsize;
 465                 if ((uio->uio_offset & (secsize - 1)) == 0 &&
 466                     (uio->uio_resid & (secsize - 1)) == 0) {
 467
 468                         /* Sync dirty pages and buffers if needed */
 469                         error = ffs_rawread_sync(vp,
 470                                                  (uio->uio_td != NULL) ?
 471                                                  uio->uio_td : curthread);
 472                         if (error != 0)
 473                                 return error;
 474
 475                         /* Check for end of file */
 476                         if (ip->i_size > uio->uio_offset) {
 477                                 filebytes = ip->i_size - uio->uio_offset;
 478
 479                                 /* No special eof handling needed ? */
 480                                 if (uio->uio_resid <= filebytes) {
 481                                         *workdone = 1;
 482                                         return ffs_rawread_main(vp, uio);
 483                                 }
 484
 485                                 partialbytes = ((unsigned int) ip->i_size) %
 486                                         ip->i_fs->fs_bsize;
 487                                 blockbytes = (int) filebytes - partialbytes;
 488                                 if (blockbytes > 0) {
 489                                         skipbytes = uio->uio_resid -
 490                                                 blockbytes;
 491                                         uio->uio_resid = blockbytes;
 492                                         error = ffs_rawread_main(vp, uio);
 493                                         uio->uio_resid += skipbytes;
 494                                         if (error != 0)
 495                                                 return error;
 496                                         /* Read remaining part using buffer */
 497                                 }
 498                         }
 499                 }
 500         }
 501         *workdone = 0;
 502         return 0;
 503 }