sys/ufs/ffs/ffs_rawread.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   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/systm.h>
  30 #include <sys/bio.h>
  31 #include <sys/buf.h>
  32 #include <sys/conf.h>
  33 #include <sys/fcntl.h>
  34 #include <sys/kernel.h>
  35 #include <sys/limits.h>
  36 #include <sys/mount.h>
  37 #include <sys/namei.h>
  38 #include <sys/proc.h>
  39 #include <sys/rwlock.h>
  40 #include <sys/stat.h>
  41 #include <sys/sysctl.h>
  42 #include <sys/vnode.h>
  43
  44 #include <ufs/ufs/extattr.h>
  45 #include <ufs/ufs/quota.h>
  46 #include <ufs/ufs/inode.h>
  47 #include <ufs/ufs/ufsmount.h>
  48 #include <ufs/ufs/ufs_extern.h>
  49 #include <ufs/ffs/fs.h>
  50 #include <ufs/ffs/ffs_extern.h>
  51
  52 #include <vm/vm.h>
  53 #include <vm/vm_extern.h>
  54 #include <vm/vm_object.h>
  55 #include <vm/vnode_pager.h>
  56
  57 static int ffs_rawread_readahead(struct vnode *vp,
  58                                  caddr_t udata,
  59                                  off_t offset,
  60                                  size_t len,
  61                                  struct thread *td,
  62                                  struct buf *bp);
  63 static int ffs_rawread_main(struct vnode *vp,
  64                             struct uio *uio);
  65
  66 static int ffs_rawread_sync(struct vnode *vp);
  67
  68 int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
  69
  70 SYSCTL_DECL(_vfs_ffs);
  71
  72 static uma_zone_t ffsraw_pbuf_zone;
  73
  74 static int allowrawread = 1;
  75 SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
  76            "Flag to enable raw reads");
  77
  78 static int rawreadahead = 1;
  79 SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
  80            "Flag to enable readahead for long raw reads");
  81
  82 static void
  83 ffs_rawread_setup(void *arg __unused)
  84 {
  85
  86         ffsraw_pbuf_zone = pbuf_zsecond_create("ffsrawpbuf",
  87             (nswbuf > 100 ) ?  (nswbuf - (nswbuf >> 4)) : nswbuf - 8);
  88 }
  89 SYSINIT(ffs_raw, SI_SUB_VM_CONF, SI_ORDER_ANY, ffs_rawread_setup, NULL);
  90
  91 static int
  92 ffs_rawread_sync(struct vnode *vp)
  93 {
  94         int error;
  95         int upgraded;
  96         struct bufobj *bo;
  97         struct mount *mp;
  98         vm_object_t obj;
  99
 100         /* Check for dirty mmap, pending writes and dirty buffers */
 101         bo = &vp->v_bufobj;
 102         BO_LOCK(bo);
 103         VI_LOCK(vp);
 104         if (bo->bo_numoutput > 0 ||
 105             bo->bo_dirty.bv_cnt > 0 ||
 106             ((obj = vp->v_object) != NULL &&
 107              vm_object_mightbedirty(obj))) {
 108                 VI_UNLOCK(vp);
 109                 BO_UNLOCK(bo);
 110
 111                 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 112                         if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
 113                                 upgraded = 1;
 114                         else
 115                                 upgraded = 0;
 116                         VOP_UNLOCK(vp);
 117                         (void) vn_start_write(vp, &mp, V_WAIT);
 118                         VOP_LOCK(vp, LK_EXCLUSIVE);
 119                 } else if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
 120                         upgraded = 1;
 121                         /* Upgrade to exclusive lock, this might block */
 122                         VOP_LOCK(vp, LK_UPGRADE);
 123                 } else
 124                         upgraded = 0;
 125
 126
 127                 VI_LOCK(vp);
 128                 /* Check if vnode was reclaimed while unlocked. */
 129                 if (VN_IS_DOOMED(vp)) {
 130                         VI_UNLOCK(vp);
 131                         if (upgraded != 0)
 132                                 VOP_LOCK(vp, LK_DOWNGRADE);
 133                         vn_finished_write(mp);
 134                         return (EIO);
 135                 }
 136                 VI_UNLOCK(vp);
 137
 138                 /* Attempt to msync mmap() regions to clean dirty mmap */
 139                 vnode_pager_clean_sync(vp);
 140
 141                 /* Wait for pending writes to complete */
 142                 BO_LOCK(bo);
 143                 error = bufobj_wwait(&vp->v_bufobj, 0, 0);
 144                 if (error != 0) {
 145                         /* XXX: can't happen with a zero timeout ??? */
 146                         BO_UNLOCK(bo);
 147                         if (upgraded != 0)
 148                                 VOP_LOCK(vp, LK_DOWNGRADE);
 149                         vn_finished_write(mp);
 150                         return (error);
 151                 }
 152                 /* Flush dirty buffers */
 153                 if (bo->bo_dirty.bv_cnt > 0) {
 154                         BO_UNLOCK(bo);
 155                         if ((error = ffs_syncvnode(vp, MNT_WAIT, 0)) != 0) {
 156                                 if (upgraded != 0)
 157                                         VOP_LOCK(vp, LK_DOWNGRADE);
 158                                 vn_finished_write(mp);
 159                                 return (error);
 160                         }
 161                         BO_LOCK(bo);
 162                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 163                                 panic("ffs_rawread_sync: dirty bufs");
 164                 }
 165                 BO_UNLOCK(bo);
 166                 if (upgraded != 0)
 167                         VOP_LOCK(vp, LK_DOWNGRADE);
 168                 vn_finished_write(mp);
 169         } else {
 170                 VI_UNLOCK(vp);
 171                 BO_UNLOCK(bo);
 172         }
 173         return 0;
 174 }
 175
 176 static int
 177 ffs_rawread_readahead(struct vnode *vp,
 178                       caddr_t udata,
 179                       off_t offset,
 180                       size_t len,
 181                       struct thread *td,
 182                       struct buf *bp)
 183 {
 184         int error;
 185         uint64_t iolen;
 186         off_t blockno;
 187         int blockoff;
 188         int bsize;
 189         struct vnode *dp;
 190         int bforwards;
 191         struct inode *ip;
 192         ufs2_daddr_t blkno;
 193
 194         bsize = vp->v_mount->mnt_stat.f_iosize;
 195
 196         ip = VTOI(vp);
 197         dp = ITODEVVP(ip);
 198
 199         iolen = ((vm_offset_t) udata) & PAGE_MASK;
 200         bp->b_bcount = len;
 201         if (bp->b_bcount + iolen > bp->b_kvasize) {
 202                 bp->b_bcount = bp->b_kvasize;
 203                 if (iolen != 0)
 204                         bp->b_bcount -= PAGE_SIZE;
 205         }
 206         bp->b_flags = 0;        /* XXX necessary ? */
 207         bp->b_iocmd = BIO_READ;
 208         bp->b_iodone = bdone;
 209         blockno = offset / bsize;
 210         blockoff = (offset % bsize) / DEV_BSIZE;
 211         if ((daddr_t) blockno != blockno) {
 212                 return EINVAL; /* blockno overflow */
 213         }
 214
 215         bp->b_lblkno = bp->b_blkno = blockno;
 216
 217         error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL);
 218         if (error != 0)
 219                 return error;
 220         if (blkno == -1) {
 221                 /* Fill holes with NULs to preserve semantics */
 222
 223                 if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
 224                         bp->b_bcount = bsize - blockoff * DEV_BSIZE;
 225
 226                 if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
 227                         return EFAULT;
 228
 229                 maybe_yield();
 230                 bzero(bp->b_data, bp->b_bufsize);
 231
 232                 /* Mark operation completed (similar to bufdone()) */
 233
 234                 bp->b_resid = 0;
 235                 bp->b_flags |= B_DONE;
 236                 return 0;
 237         }
 238         bp->b_blkno = blkno + blockoff;
 239         bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE;
 240
 241         if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
 242                 bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
 243
 244         if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
 245                 return EFAULT;
 246
 247         BO_STRATEGY(&dp->v_bufobj, bp);
 248         return 0;
 249 }
 250
 251 static int
 252 ffs_rawread_main(struct vnode *vp,
 253                  struct uio *uio)
 254 {
 255         int error, nerror;
 256         struct buf *bp, *nbp, *tbp;
 257         uint64_t iolen;
 258         caddr_t udata;
 259         long resid;
 260         off_t offset;
 261         struct thread *td;
 262
 263         td = uio->uio_td ? uio->uio_td : curthread;
 264         udata = uio->uio_iov->iov_base;
 265         resid = uio->uio_resid;
 266         offset = uio->uio_offset;
 267
 268         /*
 269          * keep the process from being swapped
 270          */
 271         PHOLD(td->td_proc);
 272
 273         error = 0;
 274         nerror = 0;
 275
 276         bp = NULL;
 277         nbp = NULL;
 278
 279         while (resid > 0) {
 280
 281                 if (bp == NULL) { /* Setup first read */
 282                         bp = uma_zalloc(ffsraw_pbuf_zone, M_WAITOK);
 283                         pbgetvp(vp, bp);
 284                         error = ffs_rawread_readahead(vp, udata, offset,
 285                                                      resid, td, bp);
 286                         if (error != 0)
 287                                 break;
 288
 289                         if (resid > bp->b_bufsize) { /* Setup fist readahead */
 290                                 if (rawreadahead != 0)
 291                                         nbp = uma_zalloc(ffsraw_pbuf_zone,
 292                                             M_NOWAIT);
 293                                 else
 294                                         nbp = NULL;
 295                                 if (nbp != NULL) {
 296                                         pbgetvp(vp, nbp);
 297
 298                                         nerror = ffs_rawread_readahead(vp,
 299                                                                        udata +
 300                                                                        bp->b_bufsize,
 301                                                                        offset +
 302                                                                        bp->b_bufsize,
 303                                                                        resid -
 304                                                                        bp->b_bufsize,
 305                                                                        td,
 306                                                                        nbp);
 307                                         if (nerror) {
 308                                                 pbrelvp(nbp);
 309                                                 uma_zfree(ffsraw_pbuf_zone,
 310                                                     nbp);
 311                                                 nbp = NULL;
 312                                         }
 313                                 }
 314                         }
 315                 }
 316
 317                 bwait(bp, PRIBIO, "rawrd");
 318                 vunmapbuf(bp);
 319
 320                 iolen = bp->b_bcount - bp->b_resid;
 321                 if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
 322                         nerror = 0;     /* Ignore possible beyond EOF error */
 323                         break; /* EOF */
 324                 }
 325
 326                 if ((bp->b_ioflags & BIO_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                                                       td,
 340                                                       bp);
 341                         if (error != 0)
 342                                 break;
 343                 } else if (nbp != NULL) { /* Complete read with readahead */
 344
 345                         tbp = bp;
 346                         bp = nbp;
 347                         nbp = tbp;
 348
 349                         if (resid <= bp->b_bufsize) { /* No more readaheads */
 350                                 pbrelvp(nbp);
 351                                 uma_zfree(ffsraw_pbuf_zone, nbp);
 352                                 nbp = NULL;
 353                         } else { /* Setup next readahead */
 354                                 nerror = ffs_rawread_readahead(vp,
 355                                                                udata +
 356                                                                bp->b_bufsize,
 357                                                                offset +
 358                                                                bp->b_bufsize,
 359                                                                resid -
 360                                                                bp->b_bufsize,
 361                                                                td,
 362                                                                nbp);
 363                                 if (nerror != 0) {
 364                                         pbrelvp(nbp);
 365                                         uma_zfree(ffsraw_pbuf_zone, nbp);
 366                                         nbp = NULL;
 367                                 }
 368                         }
 369                 } else if (nerror != 0) {/* Deferred Readahead error */
 370                         break;
 371                 }  else if (resid > 0) { /* More to read, no readahead */
 372                         error = ffs_rawread_readahead(vp, udata, offset,
 373                                                       resid, td, bp);
 374                         if (error != 0)
 375                                 break;
 376                 }
 377         }
 378
 379         if (bp != NULL) {
 380                 pbrelvp(bp);
 381                 uma_zfree(ffsraw_pbuf_zone, bp);
 382         }
 383         if (nbp != NULL) {                      /* Run down readahead buffer */
 384                 bwait(nbp, PRIBIO, "rawrd");
 385                 vunmapbuf(nbp);
 386                 pbrelvp(nbp);
 387                 uma_zfree(ffsraw_pbuf_zone, nbp);
 388         }
 389
 390         if (error == 0)
 391                 error = nerror;
 392         PRELE(td->td_proc);
 393         uio->uio_iov->iov_base = udata;
 394         uio->uio_resid = resid;
 395         uio->uio_offset = offset;
 396         return error;
 397 }
 398
 399 int
 400 ffs_rawread(struct vnode *vp,
 401             struct uio *uio,
 402             int *workdone)
 403 {
 404         if (allowrawread != 0 &&
 405             uio->uio_iovcnt == 1 &&
 406             uio->uio_segflg == UIO_USERSPACE &&
 407             uio->uio_resid == uio->uio_iov->iov_len &&
 408             (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags &
 409              TDP_DEADLKTREAT) == 0) {
 410                 int secsize;            /* Media sector size */
 411                 off_t filebytes;        /* Bytes left of file */
 412                 int blockbytes;         /* Bytes left of file in full blocks */
 413                 int partialbytes;       /* Bytes in last partial block */
 414                 int skipbytes;          /* Bytes not to read in ffs_rawread */
 415                 struct inode *ip;
 416                 int error;
 417
 418
 419                 /* Only handle sector aligned reads */
 420                 ip = VTOI(vp);
 421                 secsize = ITODEVVP(ip)->v_bufobj.bo_bsize;
 422                 if ((uio->uio_offset & (secsize - 1)) == 0 &&
 423                     (uio->uio_resid & (secsize - 1)) == 0) {
 424
 425                         /* Sync dirty pages and buffers if needed */
 426                         error = ffs_rawread_sync(vp);
 427                         if (error != 0)
 428                                 return error;
 429
 430                         /* Check for end of file */
 431                         if (ip->i_size > uio->uio_offset) {
 432                                 filebytes = ip->i_size - uio->uio_offset;
 433
 434                                 /* No special eof handling needed ? */
 435                                 if (uio->uio_resid <= filebytes) {
 436                                         *workdone = 1;
 437                                         return ffs_rawread_main(vp, uio);
 438                                 }
 439
 440                                 partialbytes = ((unsigned int) ip->i_size) %
 441                                     ITOFS(ip)->fs_bsize;
 442                                 blockbytes = (int) filebytes - partialbytes;
 443                                 if (blockbytes > 0) {
 444                                         skipbytes = uio->uio_resid -
 445                                                 blockbytes;
 446                                         uio->uio_resid = blockbytes;
 447                                         error = ffs_rawread_main(vp, uio);
 448                                         uio->uio_resid += skipbytes;
 449                                         if (error != 0)
 450                                                 return error;
 451                                         /* Read remaining part using buffer */
 452                                 }
 453                         }
 454                 }
 455         }
 456         *workdone = 0;
 457         return 0;
 458 }