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 <sys/rwlock.h>
  46 #include <ufs/ufs/extattr.h>
  47 #include <ufs/ufs/quota.h>
  48 #include <ufs/ufs/inode.h>
  49 #include <ufs/ufs/ufsmount.h>
  50 #include <ufs/ufs/ufs_extern.h>
  51 #include <ufs/ffs/fs.h>
  52 #include <ufs/ffs/ffs_extern.h>
  53
  54 #include <vm/vm.h>
  55 #include <vm/vm_extern.h>
  56 #include <vm/vm_object.h>
  57 #include <sys/kernel.h>
  58 #include <sys/sysctl.h>
  59
  60 static int ffs_rawread_readahead(struct vnode *vp,
  61                                  caddr_t udata,
  62                                  off_t offset,
  63                                  size_t len,
  64                                  struct thread *td,
  65                                  struct buf *bp,
  66                                  caddr_t sa);
  67 static int ffs_rawread_main(struct vnode *vp,
  68                             struct uio *uio);
  69
  70 static int ffs_rawread_sync(struct vnode *vp);
  71
  72 int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
  73
  74 SYSCTL_DECL(_vfs_ffs);
  75
  76 static int ffsrawbufcnt = 4;
  77 SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
  78            "Buffers available for raw reads");
  79
  80 static int allowrawread = 1;
  81 SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
  82            "Flag to enable raw reads");
  83
  84 static int rawreadahead = 1;
  85 SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
  86            "Flag to enable readahead for long raw reads");
  87
  88 static void
  89 ffs_rawread_setup(void *arg __unused)
  90 {
  91
  92         ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
  93 }
  94 SYSINIT(ffs_raw, SI_SUB_VM_CONF, SI_ORDER_ANY, ffs_rawread_setup, NULL);
  95
  96 static int
  97 ffs_rawread_sync(struct vnode *vp)
  98 {
  99         int error;
 100         int upgraded;
 101         struct bufobj *bo;
 102         struct mount *mp;
 103         vm_object_t obj;
 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             ((obj = vp->v_object) != NULL &&
 112              (obj->flags & OBJ_MIGHTBEDIRTY) != 0)) {
 113                 VI_UNLOCK(vp);
 114                 BO_UNLOCK(bo);
 115
 116                 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 117                         if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
 118                                 upgraded = 1;
 119                         else
 120                                 upgraded = 0;
 121                         VOP_UNLOCK(vp, 0);
 122                         (void) vn_start_write(vp, &mp, V_WAIT);
 123                         VOP_LOCK(vp, LK_EXCLUSIVE);
 124                 } else if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
 125                         upgraded = 1;
 126                         /* Upgrade to exclusive lock, this might block */
 127                         VOP_LOCK(vp, LK_UPGRADE);
 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);
 138                         vn_finished_write(mp);
 139                         return (EIO);
 140                 }
 141                 /* Attempt to msync mmap() regions to clean dirty mmap */
 142                 if ((obj = vp->v_object) != NULL &&
 143                     (obj->flags & OBJ_MIGHTBEDIRTY) != 0) {
 144                         VI_UNLOCK(vp);
 145                         VM_OBJECT_WLOCK(obj);
 146                         vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
 147                         VM_OBJECT_WUNLOCK(obj);
 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)) != 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, 1) < 0)
 243                         return EFAULT;
 244
 245                 maybe_yield();
 246                 bzero(bp->b_data, bp->b_bufsize);
 247
 248                 /* Mark operation completed (similar to bufdone()) */
 249
 250                 bp->b_resid = 0;
 251                 bp->b_flags |= B_DONE;
 252                 return 0;
 253         }
 254         bp->b_blkno = blkno + blockoff;
 255         bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE;
 256
 257         if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
 258                 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
 259         bp->b_bufsize = bp->b_bcount;
 260
 261         if (vmapbuf(bp, 1) < 0)
 262                 return EFAULT;
 263
 264         BO_STRATEGY(&dp->v_bufobj, bp);
 265         return 0;
 266 }
 267
 268
 269 static int
 270 ffs_rawread_main(struct vnode *vp,
 271                  struct uio *uio)
 272 {
 273         int error, nerror;
 274         struct buf *bp, *nbp, *tbp;
 275         caddr_t sa, nsa, tsa;
 276         u_int iolen;
 277         caddr_t udata;
 278         long resid;
 279         off_t offset;
 280         struct thread *td;
 281
 282         td = uio->uio_td ? uio->uio_td : curthread;
 283         udata = uio->uio_iov->iov_base;
 284         resid = uio->uio_resid;
 285         offset = uio->uio_offset;
 286
 287         /*
 288          * keep the process from being swapped
 289          */
 290         PHOLD(td->td_proc);
 291
 292         error = 0;
 293         nerror = 0;
 294
 295         bp = NULL;
 296         nbp = NULL;
 297         sa = NULL;
 298         nsa = NULL;
 299
 300         while (resid > 0) {
 301
 302                 if (bp == NULL) { /* Setup first read */
 303                         /* XXX: Leave some bufs for swap */
 304                         bp = getpbuf(&ffsrawbufcnt);
 305                         sa = bp->b_data;
 306                         pbgetvp(vp, bp);
 307                         error = ffs_rawread_readahead(vp, udata, offset,
 308                                                      resid, td, bp, sa);
 309                         if (error != 0)
 310                                 break;
 311
 312                         if (resid > bp->b_bufsize) { /* Setup fist readahead */
 313                                 /* XXX: Leave bufs for swap */
 314                                 if (rawreadahead != 0)
 315                                         nbp = trypbuf(&ffsrawbufcnt);
 316                                 else
 317                                         nbp = NULL;
 318                                 if (nbp != NULL) {
 319                                         nsa = nbp->b_data;
 320                                         pbgetvp(vp, nbp);
 321
 322                                         nerror = ffs_rawread_readahead(vp,
 323                                                                        udata +
 324                                                                        bp->b_bufsize,
 325                                                                        offset +
 326                                                                        bp->b_bufsize,
 327                                                                        resid -
 328                                                                        bp->b_bufsize,
 329                                                                        td,
 330                                                                        nbp,
 331                                                                        nsa);
 332                                         if (nerror) {
 333                                                 pbrelvp(nbp);
 334                                                 relpbuf(nbp, &ffsrawbufcnt);
 335                                                 nbp = NULL;
 336                                         }
 337                                 }
 338                         }
 339                 }
 340
 341                 bwait(bp, PRIBIO, "rawrd");
 342                 vunmapbuf(bp);
 343
 344                 iolen = bp->b_bcount - bp->b_resid;
 345                 if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
 346                         nerror = 0;     /* Ignore possible beyond EOF error */
 347                         break; /* EOF */
 348                 }
 349
 350                 if ((bp->b_ioflags & BIO_ERROR) != 0) {
 351                         error = bp->b_error;
 352                         break;
 353                 }
 354                 resid -= iolen;
 355                 udata += iolen;
 356                 offset += iolen;
 357                 if (iolen < bp->b_bufsize) {
 358                         /* Incomplete read.  Try to read remaining part */
 359                         error = ffs_rawread_readahead(vp,
 360                                                       udata,
 361                                                       offset,
 362                                                       bp->b_bufsize - iolen,
 363                                                       td,
 364                                                       bp,
 365                                                       sa);
 366                         if (error != 0)
 367                                 break;
 368                 } else if (nbp != NULL) { /* Complete read with readahead */
 369
 370                         tbp = bp;
 371                         bp = nbp;
 372                         nbp = tbp;
 373
 374                         tsa = sa;
 375                         sa = nsa;
 376                         nsa = tsa;
 377
 378                         if (resid <= bp->b_bufsize) { /* No more readaheads */
 379                                 pbrelvp(nbp);
 380                                 relpbuf(nbp, &ffsrawbufcnt);
 381                                 nbp = NULL;
 382                         } else { /* Setup next readahead */
 383                                 nerror = ffs_rawread_readahead(vp,
 384                                                                udata +
 385                                                                bp->b_bufsize,
 386                                                                offset +
 387                                                                bp->b_bufsize,
 388                                                                resid -
 389                                                                bp->b_bufsize,
 390                                                                td,
 391                                                                nbp,
 392                                                                nsa);
 393                                 if (nerror != 0) {
 394                                         pbrelvp(nbp);
 395                                         relpbuf(nbp, &ffsrawbufcnt);
 396                                         nbp = NULL;
 397                                 }
 398                         }
 399                 } else if (nerror != 0) {/* Deferred Readahead error */
 400                         break;
 401                 }  else if (resid > 0) { /* More to read, no readahead */
 402                         error = ffs_rawread_readahead(vp, udata, offset,
 403                                                       resid, td, bp, sa);
 404                         if (error != 0)
 405                                 break;
 406                 }
 407         }
 408
 409         if (bp != NULL) {
 410                 pbrelvp(bp);
 411                 relpbuf(bp, &ffsrawbufcnt);
 412         }
 413         if (nbp != NULL) {                      /* Run down readahead buffer */
 414                 bwait(nbp, PRIBIO, "rawrd");
 415                 vunmapbuf(nbp);
 416                 pbrelvp(nbp);
 417                 relpbuf(nbp, &ffsrawbufcnt);
 418         }
 419
 420         if (error == 0)
 421                 error = nerror;
 422         PRELE(td->td_proc);
 423         uio->uio_iov->iov_base = udata;
 424         uio->uio_resid = resid;
 425         uio->uio_offset = offset;
 426         return error;
 427 }
 428
 429
 430 int
 431 ffs_rawread(struct vnode *vp,
 432             struct uio *uio,
 433             int *workdone)
 434 {
 435         if (allowrawread != 0 &&
 436             uio->uio_iovcnt == 1 &&
 437             uio->uio_segflg == UIO_USERSPACE &&
 438             uio->uio_resid == uio->uio_iov->iov_len &&
 439             (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags &
 440              TDP_DEADLKTREAT) == 0) {
 441                 int secsize;            /* Media sector size */
 442                 off_t filebytes;        /* Bytes left of file */
 443                 int blockbytes;         /* Bytes left of file in full blocks */
 444                 int partialbytes;       /* Bytes in last partial block */
 445                 int skipbytes;          /* Bytes not to read in ffs_rawread */
 446                 struct inode *ip;
 447                 int error;
 448
 449
 450                 /* Only handle sector aligned reads */
 451                 ip = VTOI(vp);
 452                 secsize = ip->i_devvp->v_bufobj.bo_bsize;
 453                 if ((uio->uio_offset & (secsize - 1)) == 0 &&
 454                     (uio->uio_resid & (secsize - 1)) == 0) {
 455
 456                         /* Sync dirty pages and buffers if needed */
 457                         error = ffs_rawread_sync(vp);
 458                         if (error != 0)
 459                                 return error;
 460
 461                         /* Check for end of file */
 462                         if (ip->i_size > uio->uio_offset) {
 463                                 filebytes = ip->i_size - uio->uio_offset;
 464
 465                                 /* No special eof handling needed ? */
 466                                 if (uio->uio_resid <= filebytes) {
 467                                         *workdone = 1;
 468                                         return ffs_rawread_main(vp, uio);
 469                                 }
 470
 471                                 partialbytes = ((unsigned int) ip->i_size) %
 472                                         ip->i_fs->fs_bsize;
 473                                 blockbytes = (int) filebytes - partialbytes;
 474                                 if (blockbytes > 0) {
 475                                         skipbytes = uio->uio_resid -
 476                                                 blockbytes;
 477                                         uio->uio_resid = blockbytes;
 478                                         error = ffs_rawread_main(vp, uio);
 479                                         uio->uio_resid += skipbytes;
 480                                         if (error != 0)
 481                                                 return error;
 482                                         /* Read remaining part using buffer */
 483                                 }
 484                         }
 485                 }
 486         }
 487         *workdone = 0;
 488         return 0;
 489 }