sys/vfs/ufs/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  * $FreeBSD: src/sys/ufs/ffs/ffs_rawread.c,v 1.3.2.2 2003/05/29 06:15:35 alc Exp $
  27  * $DragonFly: src/sys/vfs/ufs/ffs_rawread.c,v 1.2 2003/06/17 04:28:59 dillon Exp $
  28  */
  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/mount.h>
  37 #include <sys/namei.h>
  38 #include <sys/vnode.h>
  39 #include <sys/conf.h>
  40 #include <sys/filio.h>
  41 #include <sys/ttycom.h>
  42 #include <sys/buf.h>
  43 #include <ufs/ufs/quota.h>
  44 #include <ufs/ufs/inode.h>
  45 #include <ufs/ffs/fs.h>
  46
  47 #include <machine/limits.h>
  48 #include <vm/vm.h>
  49 #include <vm/vm_extern.h>
  50 #include <vm/vm_object.h>
  51 #include <sys/kernel.h>
  52 #include <sys/sysctl.h>
  53
  54 static int ffs_rawread_readahead(struct vnode *vp,
  55                                  caddr_t udata,
  56                                  off_t offset,
  57                                  size_t len,
  58                                  struct proc *p,
  59                                  struct buf *bp,
  60                                  caddr_t sa);
  61 static int ffs_rawread_main(struct vnode *vp,
  62                             struct uio *uio);
  63
  64 static int ffs_rawread_sync(struct vnode *vp, struct proc *p);
  65
  66 int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
  67
  68 void ffs_rawread_setup(void);
  69
  70 static void ffs_rawreadwakeup(struct buf *bp);
  71
  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
  88 void
  89 ffs_rawread_setup(void)
  90 {
  91         ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
  92 }
  93
  94
  95 static int
  96 ffs_rawread_sync(struct vnode *vp, struct proc *p)
  97 {
  98         int spl;
  99         int error;
 100         int upgraded;
 101
 102         /* Check for dirty mmap, pending writes and dirty buffers */
 103         spl = splbio();
 104         if (vp->v_numoutput > 0 ||
 105             !TAILQ_EMPTY(&vp->v_dirtyblkhd) ||
 106             (vp->v_flag & VOBJDIRTY) != 0) {
 107                 splx(spl);
 108
 109                 if (VOP_ISLOCKED(vp, p) != LK_EXCLUSIVE) {
 110                         upgraded = 1;
 111                         /* Upgrade to exclusive lock, this might block */
 112                         VOP_LOCK(vp, LK_UPGRADE | LK_NOPAUSE, p);
 113                 } else
 114                         upgraded = 0;
 115
 116                 /* Attempt to msync mmap() regions to clean dirty mmap */
 117                 if ((vp->v_flag & VOBJDIRTY) != 0) {
 118                         struct vm_object *obj;
 119                         if (VOP_GETVOBJECT(vp, &obj) == 0)
 120                                 vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
 121                 }
 122
 123                 /* Wait for pending writes to complete */
 124                 spl = splbio();
 125                 while (vp->v_numoutput) {
 126                         vp->v_flag |= VBWAIT;
 127                         error = tsleep((caddr_t)&vp->v_numoutput,
 128                                        PRIBIO + 1,
 129                                        "rawrdfls", 0);
 130                         if (error != 0) {
 131                                 splx(spl);
 132                                 if (upgraded != 0)
 133                                         VOP_LOCK(vp, LK_DOWNGRADE, p);
 134                                 return (error);
 135                         }
 136                 }
 137                 /* Flush dirty buffers */
 138                 if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
 139                         splx(spl);
 140                         if ((error = VOP_FSYNC(vp, NOCRED, MNT_WAIT, p)) != 0) {
 141                                 if (upgraded != 0)
 142                                         VOP_LOCK(vp, LK_DOWNGRADE, p);
 143                                 return (error);
 144                         }
 145                         spl = splbio();
 146                         if (vp->v_numoutput > 0 ||
 147                             !TAILQ_EMPTY(&vp->v_dirtyblkhd))
 148                                 panic("ffs_rawread_sync: dirty bufs");
 149                 }
 150                 splx(spl);
 151                 if (upgraded != 0)
 152                         VOP_LOCK(vp, LK_DOWNGRADE, p);
 153         } else {
 154                 splx(spl);
 155         }
 156         return 0;
 157 }
 158
 159
 160 static int
 161 ffs_rawread_readahead(struct vnode *vp,
 162                       caddr_t udata,
 163                       off_t offset,
 164                       size_t len,
 165                       struct proc *p,
 166                       struct buf *bp,
 167                       caddr_t sa)
 168 {
 169         int error;
 170         u_int iolen;
 171         off_t blockno;
 172         int blockoff;
 173         int bsize;
 174         struct vnode *dp;
 175         int bforwards;
 176
 177         bsize = vp->v_mount->mnt_stat.f_iosize;
 178
 179         iolen = ((vm_offset_t) udata) & PAGE_MASK;
 180         bp->b_bcount = len;
 181         if (bp->b_bcount + iolen > bp->b_kvasize) {
 182                 bp->b_bcount = bp->b_kvasize;
 183                 if (iolen != 0)
 184                         bp->b_bcount -= PAGE_SIZE;
 185         }
 186         bp->b_flags = B_PHYS | B_CALL | B_READ;
 187         bp->b_iodone = ffs_rawreadwakeup;
 188         bp->b_data = udata;
 189         bp->b_saveaddr = sa;
 190         bp->b_offset = offset;
 191         blockno = bp->b_offset / bsize;
 192         blockoff = (bp->b_offset % bsize) / DEV_BSIZE;
 193         if ((daddr_t) blockno != blockno) {
 194                 return EINVAL; /* blockno overflow */
 195         }
 196
 197         bp->b_lblkno = bp->b_blkno = blockno;
 198
 199         error = VOP_BMAP(vp, bp->b_lblkno, &dp, &bp->b_blkno, &bforwards,
 200                          NULL);
 201         if (error != 0) {
 202                 return error;
 203         }
 204         if (bp->b_blkno == -1) {
 205
 206                 /* Fill holes with NULs to preserve semantics */
 207
 208                 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
 209                         bp->b_bcount = bsize - blockoff * DEV_BSIZE;
 210                 bp->b_bufsize = bp->b_bcount;
 211
 212                 if (vmapbuf(bp) < 0)
 213                         return EFAULT;
 214
 215                 if (ticks - switchticks >= hogticks)
 216                         uio_yield();
 217                 bzero(bp->b_data, bp->b_bufsize);
 218
 219                 /* Mark operation completed (similar to bufdone()) */
 220
 221                 bp->b_resid = 0;
 222                 bp->b_flags |= B_DONE;
 223                 return 0;
 224         }
 225
 226         if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
 227                 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
 228         bp->b_bufsize = bp->b_bcount;
 229         bp->b_blkno += blockoff;
 230         bp->b_dev = dp->v_rdev;
 231
 232         if (vmapbuf(bp) < 0)
 233                 return EFAULT;
 234
 235         (void) VOP_STRATEGY(dp, bp);
 236         return 0;
 237 }
 238
 239
 240 static int
 241 ffs_rawread_main(struct vnode *vp,
 242                  struct uio *uio)
 243 {
 244         int error, nerror;
 245         struct buf *bp, *nbp, *tbp;
 246         caddr_t sa, nsa, tsa;
 247         u_int iolen;
 248         int spl;
 249         caddr_t udata;
 250         long resid;
 251         off_t offset;
 252         struct proc *p;
 253
 254         p = uio->uio_procp ? uio->uio_procp : curproc;
 255         udata = uio->uio_iov->iov_base;
 256         resid = uio->uio_resid;
 257         offset = uio->uio_offset;
 258
 259         /*
 260          * keep the process from being swapped
 261          */
 262         PHOLD(p);
 263
 264         error = 0;
 265         nerror = 0;
 266
 267         bp = NULL;
 268         nbp = NULL;
 269         sa = NULL;
 270         nsa = NULL;
 271
 272         while (resid > 0) {
 273
 274                 if (bp == NULL) { /* Setup first read */
 275                         /* XXX: Leave some bufs for swap */
 276                         bp = getpbuf(&ffsrawbufcnt);
 277                         sa = bp->b_data;
 278                         bp->b_vp = vp;
 279                         error = ffs_rawread_readahead(vp, udata, offset,
 280                                                      resid, p, bp, sa);
 281                         if (error != 0)
 282                                 break;
 283
 284                         if (resid > bp->b_bufsize) { /* Setup fist readahead */
 285                                 /* XXX: Leave bufs for swap */
 286                                 if (rawreadahead != 0)
 287                                         nbp = trypbuf(&ffsrawbufcnt);
 288                                 else
 289                                         nbp = NULL;
 290                                 if (nbp != NULL) {
 291                                         nsa = nbp->b_data;
 292                                         nbp->b_vp = vp;
 293
 294                                         nerror = ffs_rawread_readahead(vp,
 295                                                                        udata +
 296                                                                        bp->b_bufsize,
 297                                                                        offset +
 298                                                                        bp->b_bufsize,
 299                                                                        resid -
 300                                                                        bp->b_bufsize,
 301                                                                        p,
 302                                                                        nbp,
 303                                                                        nsa);
 304                                         if (nerror) {
 305                                                 relpbuf(nbp, &ffsrawbufcnt);
 306                                                 nbp = NULL;
 307                                         }
 308                                 }
 309                         }
 310                 }
 311
 312                 spl = splbio();
 313                 while ((bp->b_flags & B_DONE) == 0) {
 314                         tsleep((caddr_t)bp, PRIBIO, "rawrd", 0);
 315                 }
 316                 splx(spl);
 317
 318                 vunmapbuf(bp);
 319
 320                 iolen = bp->b_bcount - bp->b_resid;
 321                 if (iolen == 0 && (bp->b_flags & B_ERROR) == 0) {
 322                         nerror = 0;     /* Ignore possible beyond EOF error */
 323                         break; /* EOF */
 324                 }
 325
 326                 if ((bp->b_flags & B_ERROR) != 0) {
 327                         error = bp->b_error;
 328                         break;
 329                 }
 330                 resid -= iolen;
 331                 udata += iolen;
 332                 offset += iolen;
 333                 if (iolen < bp->b_bufsize) {
 334                         /* Incomplete read.  Try to read remaining part */
 335                         error = ffs_rawread_readahead(vp,
 336                                                       udata,
 337                                                       offset,
 338                                                       bp->b_bufsize - iolen,
 339                                                       p,
 340                                                       bp,
 341                                                       sa);
 342                         if (error != 0)
 343                                 break;
 344                 } else if (nbp != NULL) { /* Complete read with readahead */
 345
 346                         tbp = bp;
 347                         bp = nbp;
 348                         nbp = tbp;
 349
 350                         tsa = sa;
 351                         sa = nsa;
 352                         nsa = tsa;
 353
 354                         if (resid <= bp->b_bufsize) { /* No more readaheads */
 355                                 relpbuf(nbp, &ffsrawbufcnt);
 356                                 nbp = NULL;
 357                         } else { /* Setup next readahead */
 358                                 nerror = ffs_rawread_readahead(vp,
 359                                                                udata +
 360                                                                bp->b_bufsize,
 361                                                                offset +
 362                                                                bp->b_bufsize,
 363                                                                resid -
 364                                                                bp->b_bufsize,
 365                                                                p,
 366                                                                nbp,
 367                                                                nsa);
 368                                 if (nerror != 0) {
 369                                         relpbuf(nbp, &ffsrawbufcnt);
 370                                         nbp = NULL;
 371                                 }
 372                         }
 373                 } else if (nerror != 0) {/* Deferred Readahead error */
 374                         break;
 375                 }  else if (resid > 0) { /* More to read, no readahead */
 376                         error = ffs_rawread_readahead(vp, udata, offset,
 377                                                       resid, p, bp, sa);
 378                         if (error != 0)
 379                                 break;
 380                 }
 381         }
 382
 383         if (bp != NULL)
 384                 relpbuf(bp, &ffsrawbufcnt);
 385         if (nbp != NULL) {                      /* Run down readahead buffer */
 386                 spl = splbio();
 387                 while ((nbp->b_flags & B_DONE) == 0) {
 388                         tsleep((caddr_t)nbp, PRIBIO, "rawrd", 0);
 389                 }
 390                 splx(spl);
 391                 vunmapbuf(nbp);
 392                 relpbuf(nbp, &ffsrawbufcnt);
 393         }
 394
 395         if (error == 0)
 396                 error = nerror;
 397         PRELE(p);
 398         uio->uio_iov->iov_base = udata;
 399         uio->uio_resid = resid;
 400         uio->uio_offset = offset;
 401         return error;
 402 }
 403
 404
 405 int
 406 ffs_rawread(struct vnode *vp,
 407             struct uio *uio,
 408             int *workdone)
 409 {
 410         if (allowrawread != 0 &&
 411             uio->uio_iovcnt == 1 &&
 412             uio->uio_segflg == UIO_USERSPACE &&
 413             uio->uio_resid == uio->uio_iov->iov_len &&
 414             (((uio->uio_procp != NULL) ? uio->uio_procp : curproc)->p_flag &
 415              P_DEADLKTREAT) == 0) {
 416                 int secsize;            /* Media sector size */
 417                 off_t filebytes;        /* Bytes left of file */
 418                 int blockbytes;         /* Bytes left of file in full blocks */
 419                 int partialbytes;       /* Bytes in last partial block */
 420                 int skipbytes;          /* Bytes not to read in ffs_rawread */
 421                 struct inode *ip;
 422                 int error;
 423
 424
 425                 /* Only handle sector aligned reads */
 426                 ip = VTOI(vp);
 427                 secsize = ip->i_devvp->v_rdev->si_bsize_phys;
 428                 if ((uio->uio_offset & (secsize - 1)) == 0 &&
 429                     (uio->uio_resid & (secsize - 1)) == 0) {
 430
 431                         /* Sync dirty pages and buffers if needed */
 432                         error = ffs_rawread_sync(vp,
 433                                                  (uio->uio_procp != NULL) ?
 434                                                  uio->uio_procp : curproc);
 435                         if (error != 0)
 436                                 return error;
 437
 438                         /* Check for end of file */
 439                         if (ip->i_size > uio->uio_offset) {
 440                                 filebytes = ip->i_size - uio->uio_offset;
 441
 442                                 /* No special eof handling needed ? */
 443                                 if (uio->uio_resid <= filebytes) {
 444                                         *workdone = 1;
 445                                         return ffs_rawread_main(vp, uio);
 446                                 }
 447
 448                                 partialbytes = ((unsigned int) ip->i_size) %
 449                                         ip->i_fs->fs_bsize;
 450                                 blockbytes = (int) filebytes - partialbytes;
 451                                 if (blockbytes > 0) {
 452                                         skipbytes = uio->uio_resid -
 453                                                 blockbytes;
 454                                         uio->uio_resid = blockbytes;
 455                                         error = ffs_rawread_main(vp, uio);
 456                                         uio->uio_resid += skipbytes;
 457                                         if (error != 0)
 458                                                 return error;
 459                                         /* Read remaining part using buffer */
 460                                 }
 461                         }
 462                 }
 463         }
 464         *workdone = 0;
 465         return 0;
 466 }
 467
 468
 469 static void
 470 ffs_rawreadwakeup(struct buf *bp)
 471 {
 472         wakeup((caddr_t) bp);
 473 }