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 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 SYSCTL_DECL(_vfs_ffs);
  74
  75 static int ffsrawbufcnt = 4;
  76 SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
  77            "Buffers available for raw reads");
  78
  79 static int allowrawread = 1;
  80 SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
  81            "Flag to enable raw reads");
  82
  83 static int rawreadahead = 1;
  84 SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
  85            "Flag to enable readahead for long raw reads");
  86
  87 static void
  88 ffs_rawread_setup(void *arg __unused)
  89 {
  90
  91         ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
  92 }
  93 SYSINIT(ffs_raw, SI_SUB_VM_CONF, SI_ORDER_ANY, ffs_rawread_setup, NULL);
  94
  95 static int
  96 ffs_rawread_sync(struct vnode *vp)
  97 {
  98         int error;
  99         int upgraded;
 100         struct bufobj *bo;
 101         struct mount *mp;
 102         vm_object_t obj;
 103
 104         /* Check for dirty mmap, pending writes and dirty buffers */
 105         bo = &vp->v_bufobj;
 106         BO_LOCK(bo);
 107         VI_LOCK(vp);
 108         if (bo->bo_numoutput > 0 ||
 109             bo->bo_dirty.bv_cnt > 0 ||
 110             ((obj = vp->v_object) != NULL &&
 111              (obj->flags & OBJ_MIGHTBEDIRTY) != 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 ((obj = vp->v_object) != NULL &&
 142                     (obj->flags & OBJ_MIGHTBEDIRTY) != 0) {
 143                         VI_UNLOCK(vp);
 144                         VM_OBJECT_WLOCK(obj);
 145                         vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
 146                         VM_OBJECT_WUNLOCK(obj);
 147                 } else
 148                         VI_UNLOCK(vp);
 149
 150                 /* Wait for pending writes to complete */
 151                 BO_LOCK(bo);
 152                 error = bufobj_wwait(&vp->v_bufobj, 0, 0);
 153                 if (error != 0) {
 154                         /* XXX: can't happen with a zero timeout ??? */
 155                         BO_UNLOCK(bo);
 156                         if (upgraded != 0)
 157                                 VOP_LOCK(vp, LK_DOWNGRADE);
 158                         vn_finished_write(mp);
 159                         return (error);
 160                 }
 161                 /* Flush dirty buffers */
 162                 if (bo->bo_dirty.bv_cnt > 0) {
 163                         BO_UNLOCK(bo);
 164                         if ((error = ffs_syncvnode(vp, MNT_WAIT, 0)) != 0) {
 165                                 if (upgraded != 0)
 166                                         VOP_LOCK(vp, LK_DOWNGRADE);
 167                                 vn_finished_write(mp);
 168                                 return (error);
 169                         }
 170                         BO_LOCK(bo);
 171                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 172                                 panic("ffs_rawread_sync: dirty bufs");
 173                 }
 174                 BO_UNLOCK(bo);
 175                 if (upgraded != 0)
 176                         VOP_LOCK(vp, LK_DOWNGRADE);
 177                 vn_finished_write(mp);
 178         } else {
 179                 VI_UNLOCK(vp);
 180                 BO_UNLOCK(bo);
 181         }
 182         return 0;
 183 }
 184
 185
 186 static int
 187 ffs_rawread_readahead(struct vnode *vp,
 188                       caddr_t udata,
 189                       off_t offset,
 190                       size_t len,
 191                       struct thread *td,
 192                       struct buf *bp)
 193 {
 194         int error;
 195         u_int iolen;
 196         off_t blockno;
 197         int blockoff;
 198         int bsize;
 199         struct vnode *dp;
 200         int bforwards;
 201         struct inode *ip;
 202         ufs2_daddr_t blkno;
 203
 204         bsize = vp->v_mount->mnt_stat.f_iosize;
 205
 206         ip = VTOI(vp);
 207         dp = ITODEVVP(ip);
 208
 209         iolen = ((vm_offset_t) udata) & PAGE_MASK;
 210         bp->b_bcount = len;
 211         if (bp->b_bcount + iolen > bp->b_kvasize) {
 212                 bp->b_bcount = bp->b_kvasize;
 213                 if (iolen != 0)
 214                         bp->b_bcount -= PAGE_SIZE;
 215         }
 216         bp->b_flags = 0;        /* XXX necessary ? */
 217         bp->b_iocmd = BIO_READ;
 218         bp->b_iodone = bdone;
 219         bp->b_data = udata;
 220         blockno = offset / bsize;
 221         blockoff = (offset % bsize) / DEV_BSIZE;
 222         if ((daddr_t) blockno != blockno) {
 223                 return EINVAL; /* blockno overflow */
 224         }
 225
 226         bp->b_lblkno = bp->b_blkno = blockno;
 227
 228         error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL);
 229         if (error != 0)
 230                 return error;
 231         if (blkno == -1) {
 232
 233                 /* Fill holes with NULs to preserve semantics */
 234
 235                 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
 236                         bp->b_bcount = bsize - blockoff * DEV_BSIZE;
 237                 bp->b_bufsize = bp->b_bcount;
 238
 239                 if (vmapbuf(bp, 1) < 0)
 240                         return EFAULT;
 241
 242                 maybe_yield();
 243                 bzero(bp->b_data, bp->b_bufsize);
 244
 245                 /* Mark operation completed (similar to bufdone()) */
 246
 247                 bp->b_resid = 0;
 248                 bp->b_flags |= B_DONE;
 249                 return 0;
 250         }
 251         bp->b_blkno = blkno + blockoff;
 252         bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE;
 253
 254         if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
 255                 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
 256         bp->b_bufsize = bp->b_bcount;
 257
 258         if (vmapbuf(bp, 1) < 0)
 259                 return EFAULT;
 260
 261         BO_STRATEGY(&dp->v_bufobj, bp);
 262         return 0;
 263 }
 264
 265
 266 static int
 267 ffs_rawread_main(struct vnode *vp,
 268                  struct uio *uio)
 269 {
 270         int error, nerror;
 271         struct buf *bp, *nbp, *tbp;
 272         u_int iolen;
 273         caddr_t udata;
 274         long resid;
 275         off_t offset;
 276         struct thread *td;
 277
 278         td = uio->uio_td ? uio->uio_td : curthread;
 279         udata = uio->uio_iov->iov_base;
 280         resid = uio->uio_resid;
 281         offset = uio->uio_offset;
 282
 283         /*
 284          * keep the process from being swapped
 285          */
 286         PHOLD(td->td_proc);
 287
 288         error = 0;
 289         nerror = 0;
 290
 291         bp = NULL;
 292         nbp = NULL;
 293
 294         while (resid > 0) {
 295
 296                 if (bp == NULL) { /* Setup first read */
 297                         /* XXX: Leave some bufs for swap */
 298                         bp = getpbuf(&ffsrawbufcnt);
 299                         pbgetvp(vp, bp);
 300                         error = ffs_rawread_readahead(vp, udata, offset,
 301                                                      resid, td, bp);
 302                         if (error != 0)
 303                                 break;
 304
 305                         if (resid > bp->b_bufsize) { /* Setup fist readahead */
 306                                 /* XXX: Leave bufs for swap */
 307                                 if (rawreadahead != 0)
 308                                         nbp = trypbuf(&ffsrawbufcnt);
 309                                 else
 310                                         nbp = NULL;
 311                                 if (nbp != NULL) {
 312                                         pbgetvp(vp, nbp);
 313
 314                                         nerror = ffs_rawread_readahead(vp,
 315                                                                        udata +
 316                                                                        bp->b_bufsize,
 317                                                                        offset +
 318                                                                        bp->b_bufsize,
 319                                                                        resid -
 320                                                                        bp->b_bufsize,
 321                                                                        td,
 322                                                                        nbp);
 323                                         if (nerror) {
 324                                                 pbrelvp(nbp);
 325                                                 relpbuf(nbp, &ffsrawbufcnt);
 326                                                 nbp = NULL;
 327                                         }
 328                                 }
 329                         }
 330                 }
 331
 332                 bwait(bp, PRIBIO, "rawrd");
 333                 vunmapbuf(bp);
 334
 335                 iolen = bp->b_bcount - bp->b_resid;
 336                 if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
 337                         nerror = 0;     /* Ignore possible beyond EOF error */
 338                         break; /* EOF */
 339                 }
 340
 341                 if ((bp->b_ioflags & BIO_ERROR) != 0) {
 342                         error = bp->b_error;
 343                         break;
 344                 }
 345                 resid -= iolen;
 346                 udata += iolen;
 347                 offset += iolen;
 348                 if (iolen < bp->b_bufsize) {
 349                         /* Incomplete read.  Try to read remaining part */
 350                         error = ffs_rawread_readahead(vp,
 351                                                       udata,
 352                                                       offset,
 353                                                       bp->b_bufsize - iolen,
 354                                                       td,
 355                                                       bp);
 356                         if (error != 0)
 357                                 break;
 358                 } else if (nbp != NULL) { /* Complete read with readahead */
 359
 360                         tbp = bp;
 361                         bp = nbp;
 362                         nbp = tbp;
 363
 364                         if (resid <= bp->b_bufsize) { /* No more readaheads */
 365                                 pbrelvp(nbp);
 366                                 relpbuf(nbp, &ffsrawbufcnt);
 367                                 nbp = NULL;
 368                         } else { /* Setup next readahead */
 369                                 nerror = ffs_rawread_readahead(vp,
 370                                                                udata +
 371                                                                bp->b_bufsize,
 372                                                                offset +
 373                                                                bp->b_bufsize,
 374                                                                resid -
 375                                                                bp->b_bufsize,
 376                                                                td,
 377                                                                nbp);
 378                                 if (nerror != 0) {
 379                                         pbrelvp(nbp);
 380                                         relpbuf(nbp, &ffsrawbufcnt);
 381                                         nbp = NULL;
 382                                 }
 383                         }
 384                 } else if (nerror != 0) {/* Deferred Readahead error */
 385                         break;
 386                 }  else if (resid > 0) { /* More to read, no readahead */
 387                         error = ffs_rawread_readahead(vp, udata, offset,
 388                                                       resid, td, bp);
 389                         if (error != 0)
 390                                 break;
 391                 }
 392         }
 393
 394         if (bp != NULL) {
 395                 pbrelvp(bp);
 396                 relpbuf(bp, &ffsrawbufcnt);
 397         }
 398         if (nbp != NULL) {                      /* Run down readahead buffer */
 399                 bwait(nbp, PRIBIO, "rawrd");
 400                 vunmapbuf(nbp);
 401                 pbrelvp(nbp);
 402                 relpbuf(nbp, &ffsrawbufcnt);
 403         }
 404
 405         if (error == 0)
 406                 error = nerror;
 407         PRELE(td->td_proc);
 408         uio->uio_iov->iov_base = udata;
 409         uio->uio_resid = resid;
 410         uio->uio_offset = offset;
 411         return error;
 412 }
 413
 414
 415 int
 416 ffs_rawread(struct vnode *vp,
 417             struct uio *uio,
 418             int *workdone)
 419 {
 420         if (allowrawread != 0 &&
 421             uio->uio_iovcnt == 1 &&
 422             uio->uio_segflg == UIO_USERSPACE &&
 423             uio->uio_resid == uio->uio_iov->iov_len &&
 424             (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags &
 425              TDP_DEADLKTREAT) == 0) {
 426                 int secsize;            /* Media sector size */
 427                 off_t filebytes;        /* Bytes left of file */
 428                 int blockbytes;         /* Bytes left of file in full blocks */
 429                 int partialbytes;       /* Bytes in last partial block */
 430                 int skipbytes;          /* Bytes not to read in ffs_rawread */
 431                 struct inode *ip;
 432                 int error;
 433
 434
 435                 /* Only handle sector aligned reads */
 436                 ip = VTOI(vp);
 437                 secsize = ITODEVVP(ip)->v_bufobj.bo_bsize;
 438                 if ((uio->uio_offset & (secsize - 1)) == 0 &&
 439                     (uio->uio_resid & (secsize - 1)) == 0) {
 440
 441                         /* Sync dirty pages and buffers if needed */
 442                         error = ffs_rawread_sync(vp);
 443                         if (error != 0)
 444                                 return error;
 445
 446                         /* Check for end of file */
 447                         if (ip->i_size > uio->uio_offset) {
 448                                 filebytes = ip->i_size - uio->uio_offset;
 449
 450                                 /* No special eof handling needed ? */
 451                                 if (uio->uio_resid <= filebytes) {
 452                                         *workdone = 1;
 453                                         return ffs_rawread_main(vp, uio);
 454                                 }
 455
 456                                 partialbytes = ((unsigned int) ip->i_size) %
 457                                     ITOFS(ip)->fs_bsize;
 458                                 blockbytes = (int) filebytes - partialbytes;
 459                                 if (blockbytes > 0) {
 460                                         skipbytes = uio->uio_resid -
 461                                                 blockbytes;
 462                                         uio->uio_resid = blockbytes;
 463                                         error = ffs_rawread_main(vp, uio);
 464                                         uio->uio_resid += skipbytes;
 465                                         if (error != 0)
 466                                                 return error;
 467                                         /* Read remaining part using buffer */
 468                                 }
 469                         }
 470                 }
 471         }
 472         *workdone = 0;
 473         return 0;
 474 }