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         blockno = offset / bsize;
 220         blockoff = (offset % bsize) / DEV_BSIZE;
 221         if ((daddr_t) blockno != blockno) {
 222                 return EINVAL; /* blockno overflow */
 223         }
 224
 225         bp->b_lblkno = bp->b_blkno = blockno;
 226
 227         error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL);
 228         if (error != 0)
 229                 return error;
 230         if (blkno == -1) {
 231                 /* Fill holes with NULs to preserve semantics */
 232
 233                 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
 234                         bp->b_bcount = bsize - blockoff * DEV_BSIZE;
 235
 236                 if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
 237                         return EFAULT;
 238
 239                 maybe_yield();
 240                 bzero(bp->b_data, bp->b_bufsize);
 241
 242                 /* Mark operation completed (similar to bufdone()) */
 243
 244                 bp->b_resid = 0;
 245                 bp->b_flags |= B_DONE;
 246                 return 0;
 247         }
 248         bp->b_blkno = blkno + blockoff;
 249         bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE;
 250
 251         if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
 252                 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
 253
 254         if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
 255                 return EFAULT;
 256
 257         BO_STRATEGY(&dp->v_bufobj, bp);
 258         return 0;
 259 }
 260
 261 static int
 262 ffs_rawread_main(struct vnode *vp,
 263                  struct uio *uio)
 264 {
 265         int error, nerror;
 266         struct buf *bp, *nbp, *tbp;
 267         u_int iolen;
 268         caddr_t udata;
 269         long resid;
 270         off_t offset;
 271         struct thread *td;
 272
 273         td = uio->uio_td ? uio->uio_td : curthread;
 274         udata = uio->uio_iov->iov_base;
 275         resid = uio->uio_resid;
 276         offset = uio->uio_offset;
 277
 278         /*
 279          * keep the process from being swapped
 280          */
 281         PHOLD(td->td_proc);
 282
 283         error = 0;
 284         nerror = 0;
 285
 286         bp = NULL;
 287         nbp = NULL;
 288
 289         while (resid > 0) {
 290
 291                 if (bp == NULL) { /* Setup first read */
 292                         bp = uma_zalloc(ffsraw_pbuf_zone, M_WAITOK);
 293                         pbgetvp(vp, bp);
 294                         error = ffs_rawread_readahead(vp, udata, offset,
 295                                                      resid, td, bp);
 296                         if (error != 0)
 297                                 break;
 298
 299                         if (resid > bp->b_bufsize) { /* Setup fist readahead */
 300                                 if (rawreadahead != 0)
 301                                         nbp = uma_zalloc(ffsraw_pbuf_zone,
 302                                             M_NOWAIT);
 303                                 else
 304                                         nbp = NULL;
 305                                 if (nbp != NULL) {
 306                                         pbgetvp(vp, nbp);
 307
 308                                         nerror = ffs_rawread_readahead(vp,
 309                                                                        udata +
 310                                                                        bp->b_bufsize,
 311                                                                        offset +
 312                                                                        bp->b_bufsize,
 313                                                                        resid -
 314                                                                        bp->b_bufsize,
 315                                                                        td,
 316                                                                        nbp);
 317                                         if (nerror) {
 318                                                 pbrelvp(nbp);
 319                                                 uma_zfree(ffsraw_pbuf_zone,
 320                                                     nbp);
 321                                                 nbp = NULL;
 322                                         }
 323                                 }
 324                         }
 325                 }
 326
 327                 bwait(bp, PRIBIO, "rawrd");
 328                 vunmapbuf(bp);
 329
 330                 iolen = bp->b_bcount - bp->b_resid;
 331                 if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
 332                         nerror = 0;     /* Ignore possible beyond EOF error */
 333                         break; /* EOF */
 334                 }
 335
 336                 if ((bp->b_ioflags & BIO_ERROR) != 0) {
 337                         error = bp->b_error;
 338                         break;
 339                 }
 340                 resid -= iolen;
 341                 udata += iolen;
 342                 offset += iolen;
 343                 if (iolen < bp->b_bufsize) {
 344                         /* Incomplete read.  Try to read remaining part */
 345                         error = ffs_rawread_readahead(vp,
 346                                                       udata,
 347                                                       offset,
 348                                                       bp->b_bufsize - iolen,
 349                                                       td,
 350                                                       bp);
 351                         if (error != 0)
 352                                 break;
 353                 } else if (nbp != NULL) { /* Complete read with readahead */
 354
 355                         tbp = bp;
 356                         bp = nbp;
 357                         nbp = tbp;
 358
 359                         if (resid <= bp->b_bufsize) { /* No more readaheads */
 360                                 pbrelvp(nbp);
 361                                 uma_zfree(ffsraw_pbuf_zone, nbp);
 362                                 nbp = NULL;
 363                         } else { /* Setup next readahead */
 364                                 nerror = ffs_rawread_readahead(vp,
 365                                                                udata +
 366                                                                bp->b_bufsize,
 367                                                                offset +
 368                                                                bp->b_bufsize,
 369                                                                resid -
 370                                                                bp->b_bufsize,
 371                                                                td,
 372                                                                nbp);
 373                                 if (nerror != 0) {
 374                                         pbrelvp(nbp);
 375                                         uma_zfree(ffsraw_pbuf_zone, nbp);
 376                                         nbp = NULL;
 377                                 }
 378                         }
 379                 } else if (nerror != 0) {/* Deferred Readahead error */
 380                         break;
 381                 }  else if (resid > 0) { /* More to read, no readahead */
 382                         error = ffs_rawread_readahead(vp, udata, offset,
 383                                                       resid, td, bp);
 384                         if (error != 0)
 385                                 break;
 386                 }
 387         }
 388
 389         if (bp != NULL) {
 390                 pbrelvp(bp);
 391                 uma_zfree(ffsraw_pbuf_zone, bp);
 392         }
 393         if (nbp != NULL) {                      /* Run down readahead buffer */
 394                 bwait(nbp, PRIBIO, "rawrd");
 395                 vunmapbuf(nbp);
 396                 pbrelvp(nbp);
 397                 uma_zfree(ffsraw_pbuf_zone, nbp);
 398         }
 399
 400         if (error == 0)
 401                 error = nerror;
 402         PRELE(td->td_proc);
 403         uio->uio_iov->iov_base = udata;
 404         uio->uio_resid = resid;
 405         uio->uio_offset = offset;
 406         return error;
 407 }
 408
 409 int
 410 ffs_rawread(struct vnode *vp,
 411             struct uio *uio,
 412             int *workdone)
 413 {
 414         if (allowrawread != 0 &&
 415             uio->uio_iovcnt == 1 &&
 416             uio->uio_segflg == UIO_USERSPACE &&
 417             uio->uio_resid == uio->uio_iov->iov_len &&
 418             (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags &
 419              TDP_DEADLKTREAT) == 0) {
 420                 int secsize;            /* Media sector size */
 421                 off_t filebytes;        /* Bytes left of file */
 422                 int blockbytes;         /* Bytes left of file in full blocks */
 423                 int partialbytes;       /* Bytes in last partial block */
 424                 int skipbytes;          /* Bytes not to read in ffs_rawread */
 425                 struct inode *ip;
 426                 int error;
 427
 428
 429                 /* Only handle sector aligned reads */
 430                 ip = VTOI(vp);
 431                 secsize = ITODEVVP(ip)->v_bufobj.bo_bsize;
 432                 if ((uio->uio_offset & (secsize - 1)) == 0 &&
 433                     (uio->uio_resid & (secsize - 1)) == 0) {
 434
 435                         /* Sync dirty pages and buffers if needed */
 436                         error = ffs_rawread_sync(vp);
 437                         if (error != 0)
 438                                 return error;
 439
 440                         /* Check for end of file */
 441                         if (ip->i_size > uio->uio_offset) {
 442                                 filebytes = ip->i_size - uio->uio_offset;
 443
 444                                 /* No special eof handling needed ? */
 445                                 if (uio->uio_resid <= filebytes) {
 446                                         *workdone = 1;
 447                                         return ffs_rawread_main(vp, uio);
 448                                 }
 449
 450                                 partialbytes = ((unsigned int) ip->i_size) %
 451                                     ITOFS(ip)->fs_bsize;
 452                                 blockbytes = (int) filebytes - partialbytes;
 453                                 if (blockbytes > 0) {
 454                                         skipbytes = uio->uio_resid -
 455                                                 blockbytes;
 456                                         uio->uio_resid = blockbytes;
 457                                         error = ffs_rawread_main(vp, uio);
 458                                         uio->uio_resid += skipbytes;
 459                                         if (error != 0)
 460                                                 return error;
 461                                         /* Read remaining part using buffer */
 462                                 }
 463                         }
 464                 }
 465         }
 466         *workdone = 0;
 467         return 0;
 468 }