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);
  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         vm_object_t obj;
 105
 106         /* Check for dirty mmap, pending writes and dirty buffers */
 107         bo = &vp->v_bufobj;
 108         BO_LOCK(bo);
 109         VI_LOCK(vp);
 110         if (bo->bo_numoutput > 0 ||
 111             bo->bo_dirty.bv_cnt > 0 ||
 112             ((obj = vp->v_object) != NULL &&
 113              (obj->flags & OBJ_MIGHTBEDIRTY) != 0)) {
 114                 VI_UNLOCK(vp);
 115                 BO_UNLOCK(bo);
 116
 117                 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 118                         if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
 119                                 upgraded = 1;
 120                         else
 121                                 upgraded = 0;
 122                         VOP_UNLOCK(vp, 0);
 123                         (void) vn_start_write(vp, &mp, V_WAIT);
 124                         VOP_LOCK(vp, LK_EXCLUSIVE);
 125                 } else if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
 126                         upgraded = 1;
 127                         /* Upgrade to exclusive lock, this might block */
 128                         VOP_LOCK(vp, LK_UPGRADE);
 129                 } else
 130                         upgraded = 0;
 131
 132
 133                 VI_LOCK(vp);
 134                 /* Check if vnode was reclaimed while unlocked. */
 135                 if ((vp->v_iflag & VI_DOOMED) != 0) {
 136                         VI_UNLOCK(vp);
 137                         if (upgraded != 0)
 138                                 VOP_LOCK(vp, LK_DOWNGRADE);
 139                         vn_finished_write(mp);
 140                         return (EIO);
 141                 }
 142                 /* Attempt to msync mmap() regions to clean dirty mmap */
 143                 if ((obj = vp->v_object) != NULL &&
 144                     (obj->flags & OBJ_MIGHTBEDIRTY) != 0) {
 145                         VI_UNLOCK(vp);
 146                         VM_OBJECT_LOCK(obj);
 147                         vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
 148                         VM_OBJECT_UNLOCK(obj);
 149                 } else
 150                         VI_UNLOCK(vp);
 151
 152                 /* Wait for pending writes to complete */
 153                 BO_LOCK(bo);
 154                 error = bufobj_wwait(&vp->v_bufobj, 0, 0);
 155                 if (error != 0) {
 156                         /* XXX: can't happen with a zero timeout ??? */
 157                         BO_UNLOCK(bo);
 158                         if (upgraded != 0)
 159                                 VOP_LOCK(vp, LK_DOWNGRADE);
 160                         vn_finished_write(mp);
 161                         return (error);
 162                 }
 163                 /* Flush dirty buffers */
 164                 if (bo->bo_dirty.bv_cnt > 0) {
 165                         BO_UNLOCK(bo);
 166                         if ((error = ffs_syncvnode(vp, MNT_WAIT, 0)) != 0) {
 167                                 if (upgraded != 0)
 168                                         VOP_LOCK(vp, LK_DOWNGRADE);
 169                                 vn_finished_write(mp);
 170                                 return (error);
 171                         }
 172                         BO_LOCK(bo);
 173                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 174                                 panic("ffs_rawread_sync: dirty bufs");
 175                 }
 176                 BO_UNLOCK(bo);
 177                 if (upgraded != 0)
 178                         VOP_LOCK(vp, LK_DOWNGRADE);
 179                 vn_finished_write(mp);
 180         } else {
 181                 VI_UNLOCK(vp);
 182                 BO_UNLOCK(bo);
 183         }
 184         return 0;
 185 }
 186
 187
 188 static int
 189 ffs_rawread_readahead(struct vnode *vp,
 190                       caddr_t udata,
 191                       off_t offset,
 192                       size_t len,
 193                       struct thread *td,
 194                       struct buf *bp,
 195                       caddr_t sa)
 196 {
 197         int error;
 198         u_int iolen;
 199         off_t blockno;
 200         int blockoff;
 201         int bsize;
 202         struct vnode *dp;
 203         int bforwards;
 204         struct inode *ip;
 205         ufs2_daddr_t blkno;
 206
 207         bsize = vp->v_mount->mnt_stat.f_iosize;
 208
 209         ip = VTOI(vp);
 210         dp = ip->i_devvp;
 211
 212         iolen = ((vm_offset_t) udata) & PAGE_MASK;
 213         bp->b_bcount = len;
 214         if (bp->b_bcount + iolen > bp->b_kvasize) {
 215                 bp->b_bcount = bp->b_kvasize;
 216                 if (iolen != 0)
 217                         bp->b_bcount -= PAGE_SIZE;
 218         }
 219         bp->b_flags = 0;        /* XXX necessary ? */
 220         bp->b_iocmd = BIO_READ;
 221         bp->b_iodone = bdone;
 222         bp->b_data = udata;
 223         bp->b_saveaddr = sa;
 224         blockno = offset / bsize;
 225         blockoff = (offset % bsize) / DEV_BSIZE;
 226         if ((daddr_t) blockno != blockno) {
 227                 return EINVAL; /* blockno overflow */
 228         }
 229
 230         bp->b_lblkno = bp->b_blkno = blockno;
 231
 232         error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL);
 233         if (error != 0)
 234                 return error;
 235         if (blkno == -1) {
 236
 237                 /* Fill holes with NULs to preserve semantics */
 238
 239                 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
 240                         bp->b_bcount = bsize - blockoff * DEV_BSIZE;
 241                 bp->b_bufsize = bp->b_bcount;
 242
 243                 if (vmapbuf(bp, 1) < 0)
 244                         return EFAULT;
 245
 246                 maybe_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, 1) < 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 }