sys/ufs/ffs/ffs_rawread.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2000-2003 Tor Egge
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/systm.h>
  34 #include <sys/fcntl.h>
  35 #include <sys/file.h>
  36 #include <sys/stat.h>
  37 #include <sys/proc.h>
  38 #include <sys/limits.h>
  39 #include <sys/mount.h>
  40 #include <sys/namei.h>
  41 #include <sys/vnode.h>
  42 #include <sys/conf.h>
  43 #include <sys/filio.h>
  44 #include <sys/ttycom.h>
  45 #include <sys/bio.h>
  46 #include <sys/buf.h>
  47 #include <sys/rwlock.h>
  48 #include <ufs/ufs/extattr.h>
  49 #include <ufs/ufs/quota.h>
  50 #include <ufs/ufs/inode.h>
  51 #include <ufs/ufs/ufsmount.h>
  52 #include <ufs/ufs/ufs_extern.h>
  53 #include <ufs/ffs/fs.h>
  54 #include <ufs/ffs/ffs_extern.h>
  55
  56 #include <vm/vm.h>
  57 #include <vm/vm_extern.h>
  58 #include <vm/vm_object.h>
  59 #include <sys/kernel.h>
  60 #include <sys/sysctl.h>
  61
  62 static int ffs_rawread_readahead(struct vnode *vp,
  63                                  caddr_t udata,
  64                                  off_t offset,
  65                                  size_t len,
  66                                  struct thread *td,
  67                                  struct buf *bp);
  68 static int ffs_rawread_main(struct vnode *vp,
  69                             struct uio *uio);
  70
  71 static int ffs_rawread_sync(struct vnode *vp);
  72
  73 int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
  74
  75 SYSCTL_DECL(_vfs_ffs);
  76
  77 static uma_zone_t ffsraw_pbuf_zone;
  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         ffsraw_pbuf_zone = pbuf_zsecond_create("ffsrawpbuf",
  92             (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              vm_object_mightbedirty(obj))) {
 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);
 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 (VN_IS_DOOMED(vp)) {
 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                     vm_object_mightbedirty(obj)) {
 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 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                 /* Fill holes with NULs to preserve semantics */
 233
 234                 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
 235                         bp->b_bcount = bsize - blockoff * DEV_BSIZE;
 236                 bp->b_bufsize = bp->b_bcount;
 237
 238                 if (vmapbuf(bp, 1) < 0)
 239                         return EFAULT;
 240
 241                 maybe_yield();
 242                 bzero(bp->b_data, bp->b_bufsize);
 243
 244                 /* Mark operation completed (similar to bufdone()) */
 245
 246                 bp->b_resid = 0;
 247                 bp->b_flags |= B_DONE;
 248                 return 0;
 249         }
 250         bp->b_blkno = blkno + blockoff;
 251         bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE;
 252
 253         if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
 254                 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
 255         bp->b_bufsize = bp->b_bcount;
 256
 257         if (vmapbuf(bp, 1) < 0)
 258                 return EFAULT;
 259
 260         BO_STRATEGY(&dp->v_bufobj, bp);
 261         return 0;
 262 }
 263
 264 static int
 265 ffs_rawread_main(struct vnode *vp,
 266                  struct uio *uio)
 267 {
 268         int error, nerror;
 269         struct buf *bp, *nbp, *tbp;
 270         u_int iolen;
 271         caddr_t udata;
 272         long resid;
 273         off_t offset;
 274         struct thread *td;
 275
 276         td = uio->uio_td ? uio->uio_td : curthread;
 277         udata = uio->uio_iov->iov_base;
 278         resid = uio->uio_resid;
 279         offset = uio->uio_offset;
 280
 281         /*
 282          * keep the process from being swapped
 283          */
 284         PHOLD(td->td_proc);
 285
 286         error = 0;
 287         nerror = 0;
 288
 289         bp = NULL;
 290         nbp = NULL;
 291
 292         while (resid > 0) {
 293
 294                 if (bp == NULL) { /* Setup first read */
 295                         bp = uma_zalloc(ffsraw_pbuf_zone, M_WAITOK);
 296                         pbgetvp(vp, bp);
 297                         error = ffs_rawread_readahead(vp, udata, offset,
 298                                                      resid, td, bp);
 299                         if (error != 0)
 300                                 break;
 301
 302                         if (resid > bp->b_bufsize) { /* Setup fist readahead */
 303                                 if (rawreadahead != 0)
 304                                         nbp = uma_zalloc(ffsraw_pbuf_zone,
 305                                             M_NOWAIT);
 306                                 else
 307                                         nbp = NULL;
 308                                 if (nbp != NULL) {
 309                                         pbgetvp(vp, nbp);
 310
 311                                         nerror = ffs_rawread_readahead(vp,
 312                                                                        udata +
 313                                                                        bp->b_bufsize,
 314                                                                        offset +
 315                                                                        bp->b_bufsize,
 316                                                                        resid -
 317                                                                        bp->b_bufsize,
 318                                                                        td,
 319                                                                        nbp);
 320                                         if (nerror) {
 321                                                 pbrelvp(nbp);
 322                                                 uma_zfree(ffsraw_pbuf_zone,
 323                                                     nbp);
 324                                                 nbp = NULL;
 325                                         }
 326                                 }
 327                         }
 328                 }
 329
 330                 bwait(bp, PRIBIO, "rawrd");
 331                 vunmapbuf(bp);
 332
 333                 iolen = bp->b_bcount - bp->b_resid;
 334                 if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
 335                         nerror = 0;     /* Ignore possible beyond EOF error */
 336                         break; /* EOF */
 337                 }
 338
 339                 if ((bp->b_ioflags & BIO_ERROR) != 0) {
 340                         error = bp->b_error;
 341                         break;
 342                 }
 343                 resid -= iolen;
 344                 udata += iolen;
 345                 offset += iolen;
 346                 if (iolen < bp->b_bufsize) {
 347                         /* Incomplete read.  Try to read remaining part */
 348                         error = ffs_rawread_readahead(vp,
 349                                                       udata,
 350                                                       offset,
 351                                                       bp->b_bufsize - iolen,
 352                                                       td,
 353                                                       bp);
 354                         if (error != 0)
 355                                 break;
 356                 } else if (nbp != NULL) { /* Complete read with readahead */
 357
 358                         tbp = bp;
 359                         bp = nbp;
 360                         nbp = tbp;
 361
 362                         if (resid <= bp->b_bufsize) { /* No more readaheads */
 363                                 pbrelvp(nbp);
 364                                 uma_zfree(ffsraw_pbuf_zone, nbp);
 365                                 nbp = NULL;
 366                         } else { /* Setup next readahead */
 367                                 nerror = ffs_rawread_readahead(vp,
 368                                                                udata +
 369                                                                bp->b_bufsize,
 370                                                                offset +
 371                                                                bp->b_bufsize,
 372                                                                resid -
 373                                                                bp->b_bufsize,
 374                                                                td,
 375                                                                nbp);
 376                                 if (nerror != 0) {
 377                                         pbrelvp(nbp);
 378                                         uma_zfree(ffsraw_pbuf_zone, nbp);
 379                                         nbp = NULL;
 380                                 }
 381                         }
 382                 } else if (nerror != 0) {/* Deferred Readahead error */
 383                         break;
 384                 }  else if (resid > 0) { /* More to read, no readahead */
 385                         error = ffs_rawread_readahead(vp, udata, offset,
 386                                                       resid, td, bp);
 387                         if (error != 0)
 388                                 break;
 389                 }
 390         }
 391
 392         if (bp != NULL) {
 393                 pbrelvp(bp);
 394                 uma_zfree(ffsraw_pbuf_zone, bp);
 395         }
 396         if (nbp != NULL) {                      /* Run down readahead buffer */
 397                 bwait(nbp, PRIBIO, "rawrd");
 398                 vunmapbuf(nbp);
 399                 pbrelvp(nbp);
 400                 uma_zfree(ffsraw_pbuf_zone, nbp);
 401         }
 402
 403         if (error == 0)
 404                 error = nerror;
 405         PRELE(td->td_proc);
 406         uio->uio_iov->iov_base = udata;
 407         uio->uio_resid = resid;
 408         uio->uio_offset = offset;
 409         return error;
 410 }
 411
 412 int
 413 ffs_rawread(struct vnode *vp,
 414             struct uio *uio,
 415             int *workdone)
 416 {
 417         if (allowrawread != 0 &&
 418             uio->uio_iovcnt == 1 &&
 419             uio->uio_segflg == UIO_USERSPACE &&
 420             uio->uio_resid == uio->uio_iov->iov_len &&
 421             (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags &
 422              TDP_DEADLKTREAT) == 0) {
 423                 int secsize;            /* Media sector size */
 424                 off_t filebytes;        /* Bytes left of file */
 425                 int blockbytes;         /* Bytes left of file in full blocks */
 426                 int partialbytes;       /* Bytes in last partial block */
 427                 int skipbytes;          /* Bytes not to read in ffs_rawread */
 428                 struct inode *ip;
 429                 int error;
 430
 431
 432                 /* Only handle sector aligned reads */
 433                 ip = VTOI(vp);
 434                 secsize = ITODEVVP(ip)->v_bufobj.bo_bsize;
 435                 if ((uio->uio_offset & (secsize - 1)) == 0 &&
 436                     (uio->uio_resid & (secsize - 1)) == 0) {
 437
 438                         /* Sync dirty pages and buffers if needed */
 439                         error = ffs_rawread_sync(vp);
 440                         if (error != 0)
 441                                 return error;
 442
 443                         /* Check for end of file */
 444                         if (ip->i_size > uio->uio_offset) {
 445                                 filebytes = ip->i_size - uio->uio_offset;
 446
 447                                 /* No special eof handling needed ? */
 448                                 if (uio->uio_resid <= filebytes) {
 449                                         *workdone = 1;
 450                                         return ffs_rawread_main(vp, uio);
 451                                 }
 452
 453                                 partialbytes = ((unsigned int) ip->i_size) %
 454                                     ITOFS(ip)->fs_bsize;
 455                                 blockbytes = (int) filebytes - partialbytes;
 456                                 if (blockbytes > 0) {
 457                                         skipbytes = uio->uio_resid -
 458                                                 blockbytes;
 459                                         uio->uio_resid = blockbytes;
 460                                         error = ffs_rawread_main(vp, uio);
 461                                         uio->uio_resid += skipbytes;
 462                                         if (error != 0)
 463                                                 return error;
 464                                         /* Read remaining part using buffer */
 465                                 }
 466                         }
 467                 }
 468         }
 469         *workdone = 0;
 470         return 0;
 471 }