The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/fuse/fuse_io.c

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    1 /*
    2  * Copyright (c) 2007-2009 Google Inc.
    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 are
    7  * met:
    8  *
    9  * * Redistributions of source code must retain the above copyright
   10  *   notice, this list of conditions and the following disclaimer.
   11  * * Redistributions in binary form must reproduce the above
   12  *   copyright notice, this list of conditions and the following disclaimer
   13  *   in the documentation and/or other materials provided with the
   14  *   distribution.
   15  * * Neither the name of Google Inc. nor the names of its
   16  *   contributors may be used to endorse or promote products derived from
   17  *   this software without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   30  *
   31  * Copyright (C) 2005 Csaba Henk.
   32  * All rights reserved.
   33  *
   34  * Redistribution and use in source and binary forms, with or without
   35  * modification, are permitted provided that the following conditions
   36  * are met:
   37  * 1. Redistributions of source code must retain the above copyright
   38  *    notice, this list of conditions and the following disclaimer.
   39  * 2. Redistributions in binary form must reproduce the above copyright
   40  *    notice, this list of conditions and the following disclaimer in the
   41  *    documentation and/or other materials provided with the distribution.
   42  *
   43  * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   44  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   45  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   46  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
   47  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   48  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   49  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   50  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   51  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   52  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   53  * SUCH DAMAGE.
   54  */
   55 
   56 #include <sys/cdefs.h>
   57 __FBSDID("$FreeBSD$");
   58 
   59 #include <sys/types.h>
   60 #include <sys/module.h>
   61 #include <sys/systm.h>
   62 #include <sys/errno.h>
   63 #include <sys/param.h>
   64 #include <sys/kernel.h>
   65 #include <sys/conf.h>
   66 #include <sys/uio.h>
   67 #include <sys/malloc.h>
   68 #include <sys/queue.h>
   69 #include <sys/lock.h>
   70 #include <sys/sx.h>
   71 #include <sys/mutex.h>
   72 #include <sys/rwlock.h>
   73 #include <sys/proc.h>
   74 #include <sys/mount.h>
   75 #include <sys/vnode.h>
   76 #include <sys/stat.h>
   77 #include <sys/unistd.h>
   78 #include <sys/filedesc.h>
   79 #include <sys/file.h>
   80 #include <sys/fcntl.h>
   81 #include <sys/bio.h>
   82 #include <sys/buf.h>
   83 #include <sys/sysctl.h>
   84 
   85 #include <vm/vm.h>
   86 #include <vm/vm_extern.h>
   87 #include <vm/pmap.h>
   88 #include <vm/vm_map.h>
   89 #include <vm/vm_page.h>
   90 #include <vm/vm_object.h>
   91 
   92 #include "fuse.h"
   93 #include "fuse_file.h"
   94 #include "fuse_node.h"
   95 #include "fuse_internal.h"
   96 #include "fuse_ipc.h"
   97 #include "fuse_io.h"
   98 
   99 #define FUSE_DEBUG_MODULE IO
  100 #include "fuse_debug.h"
  101 
  102 
  103 static int 
  104 fuse_read_directbackend(struct vnode *vp, struct uio *uio,
  105     struct ucred *cred, struct fuse_filehandle *fufh);
  106 static int 
  107 fuse_read_biobackend(struct vnode *vp, struct uio *uio,
  108     struct ucred *cred, struct fuse_filehandle *fufh);
  109 static int 
  110 fuse_write_directbackend(struct vnode *vp, struct uio *uio,
  111     struct ucred *cred, struct fuse_filehandle *fufh, int ioflag);
  112 static int 
  113 fuse_write_biobackend(struct vnode *vp, struct uio *uio,
  114     struct ucred *cred, struct fuse_filehandle *fufh, int ioflag);
  115 
  116 int
  117 fuse_io_dispatch(struct vnode *vp, struct uio *uio, int ioflag,
  118     struct ucred *cred)
  119 {
  120         struct fuse_filehandle *fufh;
  121         int err, directio;
  122 
  123         MPASS(vp->v_type == VREG || vp->v_type == VDIR);
  124 
  125         err = fuse_filehandle_getrw(vp,
  126             (uio->uio_rw == UIO_READ) ? FUFH_RDONLY : FUFH_WRONLY, &fufh);
  127         if (err) {
  128                 printf("FUSE: io dispatch: filehandles are closed\n");
  129                 return err;
  130         }
  131         /*
  132          * Ideally, when the daemon asks for direct io at open time, the
  133          * standard file flag should be set according to this, so that would
  134          * just change the default mode, which later on could be changed via
  135          * fcntl(2).
  136          * But this doesn't work, the O_DIRECT flag gets cleared at some point
  137          * (don't know where). So to make any use of the Fuse direct_io option,
  138          * we hardwire it into the file's private data (similarly to Linux,
  139          * btw.).
  140          */
  141         directio = (ioflag & IO_DIRECT) || !fsess_opt_datacache(vnode_mount(vp));
  142 
  143         switch (uio->uio_rw) {
  144         case UIO_READ:
  145                 if (directio) {
  146                         FS_DEBUG("direct read of vnode %ju via file handle %ju\n",
  147                             (uintmax_t)VTOILLU(vp), (uintmax_t)fufh->fh_id);
  148                         err = fuse_read_directbackend(vp, uio, cred, fufh);
  149                 } else {
  150                         FS_DEBUG("buffered read of vnode %ju\n", 
  151                               (uintmax_t)VTOILLU(vp));
  152                         err = fuse_read_biobackend(vp, uio, cred, fufh);
  153                 }
  154                 break;
  155         case UIO_WRITE:
  156                 if (directio) {
  157                         FS_DEBUG("direct write of vnode %ju via file handle %ju\n",
  158                             (uintmax_t)VTOILLU(vp), (uintmax_t)fufh->fh_id);
  159                         err = fuse_write_directbackend(vp, uio, cred, fufh, ioflag);
  160                 } else {
  161                         FS_DEBUG("buffered write of vnode %ju\n", 
  162                               (uintmax_t)VTOILLU(vp));
  163                         err = fuse_write_biobackend(vp, uio, cred, fufh, ioflag);
  164                 }
  165                 break;
  166         default:
  167                 panic("uninterpreted mode passed to fuse_io_dispatch");
  168         }
  169 
  170         return (err);
  171 }
  172 
  173 static int
  174 fuse_read_biobackend(struct vnode *vp, struct uio *uio,
  175     struct ucred *cred, struct fuse_filehandle *fufh)
  176 {
  177         struct buf *bp;
  178         daddr_t lbn;
  179         int bcount;
  180         int err = 0, n = 0, on = 0;
  181         off_t filesize;
  182 
  183         const int biosize = fuse_iosize(vp);
  184 
  185         FS_DEBUG("resid=%zx offset=%jx fsize=%jx\n",
  186             uio->uio_resid, uio->uio_offset, VTOFUD(vp)->filesize);
  187 
  188         if (uio->uio_resid == 0)
  189                 return (0);
  190         if (uio->uio_offset < 0)
  191                 return (EINVAL);
  192 
  193         bcount = MIN(MAXBSIZE, biosize);
  194         filesize = VTOFUD(vp)->filesize;
  195 
  196         do {
  197                 if (fuse_isdeadfs(vp)) {
  198                         err = ENXIO;
  199                         break;
  200                 }
  201                 lbn = uio->uio_offset / biosize;
  202                 on = uio->uio_offset & (biosize - 1);
  203 
  204                 FS_DEBUG2G("biosize %d, lbn %d, on %d\n", biosize, (int)lbn, on);
  205 
  206                 /*
  207                  * Obtain the buffer cache block.  Figure out the buffer size
  208                  * when we are at EOF.  If we are modifying the size of the
  209                  * buffer based on an EOF condition we need to hold
  210                  * nfs_rslock() through obtaining the buffer to prevent
  211                  * a potential writer-appender from messing with n_size.
  212                  * Otherwise we may accidentally truncate the buffer and
  213                  * lose dirty data.
  214                  *
  215                  * Note that bcount is *not* DEV_BSIZE aligned.
  216                  */
  217                 if ((off_t)lbn * biosize >= filesize) {
  218                         bcount = 0;
  219                 } else if ((off_t)(lbn + 1) * biosize > filesize) {
  220                         bcount = filesize - (off_t)lbn *biosize;
  221                 }
  222                 bp = getblk(vp, lbn, bcount, PCATCH, 0, 0);
  223 
  224                 if (!bp)
  225                         return (EINTR);
  226 
  227                 /*
  228                  * If B_CACHE is not set, we must issue the read.  If this
  229                  * fails, we return an error.
  230                  */
  231 
  232                 if ((bp->b_flags & B_CACHE) == 0) {
  233                         bp->b_iocmd = BIO_READ;
  234                         vfs_busy_pages(bp, 0);
  235                         err = fuse_io_strategy(vp, bp);
  236                         if (err) {
  237                                 brelse(bp);
  238                                 return (err);
  239                         }
  240                 }
  241                 /*
  242                  * on is the offset into the current bp.  Figure out how many
  243                  * bytes we can copy out of the bp.  Note that bcount is
  244                  * NOT DEV_BSIZE aligned.
  245                  *
  246                  * Then figure out how many bytes we can copy into the uio.
  247                  */
  248 
  249                 n = 0;
  250                 if (on < bcount)
  251                         n = MIN((unsigned)(bcount - on), uio->uio_resid);
  252                 if (n > 0) {
  253                         FS_DEBUG2G("feeding buffeater with %d bytes of buffer %p,"
  254                                 " saying %d was asked for\n",
  255                                 n, bp->b_data + on, n + (int)bp->b_resid);
  256                         err = uiomove(bp->b_data + on, n, uio);
  257                 }
  258                 brelse(bp);
  259                 FS_DEBUG2G("end of turn, err %d, uio->uio_resid %zd, n %d\n",
  260                     err, uio->uio_resid, n);
  261         } while (err == 0 && uio->uio_resid > 0 && n > 0);
  262 
  263         return (err);
  264 }
  265 
  266 static int
  267 fuse_read_directbackend(struct vnode *vp, struct uio *uio,
  268     struct ucred *cred, struct fuse_filehandle *fufh)
  269 {
  270         struct fuse_dispatcher fdi;
  271         struct fuse_read_in *fri;
  272         int err = 0;
  273 
  274         if (uio->uio_resid == 0)
  275                 return (0);
  276 
  277         fdisp_init(&fdi, 0);
  278 
  279         /*
  280          * XXX In "normal" case we use an intermediate kernel buffer for
  281          * transmitting data from daemon's context to ours. Eventually, we should
  282          * get rid of this. Anyway, if the target uio lives in sysspace (we are
  283          * called from pageops), and the input data doesn't need kernel-side
  284          * processing (we are not called from readdir) we can already invoke
  285          * an optimized, "peer-to-peer" I/O routine.
  286          */
  287         while (uio->uio_resid > 0) {
  288                 fdi.iosize = sizeof(*fri);
  289                 fdisp_make_vp(&fdi, FUSE_READ, vp, uio->uio_td, cred);
  290                 fri = fdi.indata;
  291                 fri->fh = fufh->fh_id;
  292                 fri->offset = uio->uio_offset;
  293                 fri->size = MIN(uio->uio_resid,
  294                     fuse_get_mpdata(vp->v_mount)->max_read);
  295 
  296                 FS_DEBUG2G("fri->fh %ju, fri->offset %ju, fri->size %ju\n",
  297                         (uintmax_t)fri->fh, (uintmax_t)fri->offset, 
  298                         (uintmax_t)fri->size);
  299 
  300                 if ((err = fdisp_wait_answ(&fdi)))
  301                         goto out;
  302 
  303                 FS_DEBUG2G("complete: got iosize=%d, requested fri.size=%zd; "
  304                         "resid=%zd offset=%ju\n",
  305                         fri->size, fdi.iosize, uio->uio_resid, 
  306                         (uintmax_t)uio->uio_offset);
  307 
  308                 if ((err = uiomove(fdi.answ, MIN(fri->size, fdi.iosize), uio)))
  309                         break;
  310                 if (fdi.iosize < fri->size)
  311                         break;
  312         }
  313 
  314 out:
  315         fdisp_destroy(&fdi);
  316         return (err);
  317 }
  318 
  319 static int
  320 fuse_write_directbackend(struct vnode *vp, struct uio *uio,
  321     struct ucred *cred, struct fuse_filehandle *fufh, int ioflag)
  322 {
  323         struct fuse_vnode_data *fvdat = VTOFUD(vp);
  324         struct fuse_write_in *fwi;
  325         struct fuse_dispatcher fdi;
  326         size_t chunksize;
  327         int diff;
  328         int err = 0;
  329 
  330         if (uio->uio_resid == 0)
  331                 return (0);
  332         if (ioflag & IO_APPEND)
  333                 uio_setoffset(uio, fvdat->filesize);
  334 
  335         fdisp_init(&fdi, 0);
  336 
  337         while (uio->uio_resid > 0) {
  338                 chunksize = MIN(uio->uio_resid,
  339                     fuse_get_mpdata(vp->v_mount)->max_write);
  340 
  341                 fdi.iosize = sizeof(*fwi) + chunksize;
  342                 fdisp_make_vp(&fdi, FUSE_WRITE, vp, uio->uio_td, cred);
  343 
  344                 fwi = fdi.indata;
  345                 fwi->fh = fufh->fh_id;
  346                 fwi->offset = uio->uio_offset;
  347                 fwi->size = chunksize;
  348 
  349                 if ((err = uiomove((char *)fdi.indata + sizeof(*fwi),
  350                     chunksize, uio)))
  351                         break;
  352 
  353                 if ((err = fdisp_wait_answ(&fdi)))
  354                         break;
  355 
  356                 diff = chunksize - ((struct fuse_write_out *)fdi.answ)->size;
  357                 if (diff < 0) {
  358                         err = EINVAL;
  359                         break;
  360                 }
  361                 uio->uio_resid += diff;
  362                 uio->uio_offset -= diff;
  363                 if (uio->uio_offset > fvdat->filesize)
  364                         fuse_vnode_setsize(vp, uio->uio_offset);
  365         }
  366 
  367         fdisp_destroy(&fdi);
  368 
  369         return (err);
  370 }
  371 
  372 static int
  373 fuse_write_biobackend(struct vnode *vp, struct uio *uio,
  374     struct ucred *cred, struct fuse_filehandle *fufh, int ioflag)
  375 {
  376         struct fuse_vnode_data *fvdat = VTOFUD(vp);
  377         struct buf *bp;
  378         daddr_t lbn;
  379         int bcount;
  380         int n, on, err = 0;
  381 
  382         const int biosize = fuse_iosize(vp);
  383 
  384         KASSERT(uio->uio_rw == UIO_WRITE, ("ncl_write mode"));
  385         FS_DEBUG("resid=%zx offset=%jx fsize=%jx\n",
  386             uio->uio_resid, uio->uio_offset, fvdat->filesize);
  387         if (vp->v_type != VREG)
  388                 return (EIO);
  389         if (uio->uio_offset < 0)
  390                 return (EINVAL);
  391         if (uio->uio_resid == 0)
  392                 return (0);
  393         if (ioflag & IO_APPEND)
  394                 uio_setoffset(uio, fvdat->filesize);
  395 
  396         /*
  397          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  398          * would exceed the local maximum per-file write commit size when
  399          * combined with those, we must decide whether to flush,
  400          * go synchronous, or return err.  We don't bother checking
  401          * IO_UNIT -- we just make all writes atomic anyway, as there's
  402          * no point optimizing for something that really won't ever happen.
  403          */
  404         do {
  405                 if (fuse_isdeadfs(vp)) {
  406                         err = ENXIO;
  407                         break;
  408                 }
  409                 lbn = uio->uio_offset / biosize;
  410                 on = uio->uio_offset & (biosize - 1);
  411                 n = MIN((unsigned)(biosize - on), uio->uio_resid);
  412 
  413                 FS_DEBUG2G("lbn %ju, on %d, n %d, uio offset %ju, uio resid %zd\n",
  414                         (uintmax_t)lbn, on, n, 
  415                         (uintmax_t)uio->uio_offset, uio->uio_resid);
  416 
  417 again:
  418                 /*
  419                  * Handle direct append and file extension cases, calculate
  420                  * unaligned buffer size.
  421                  */
  422                 if (uio->uio_offset == fvdat->filesize && n) {
  423                         /*
  424                          * Get the buffer (in its pre-append state to maintain
  425                          * B_CACHE if it was previously set).  Resize the
  426                          * nfsnode after we have locked the buffer to prevent
  427                          * readers from reading garbage.
  428                          */
  429                         bcount = on;
  430                         FS_DEBUG("getting block from OS, bcount %d\n", bcount);
  431                         bp = getblk(vp, lbn, bcount, PCATCH, 0, 0);
  432 
  433                         if (bp != NULL) {
  434                                 long save;
  435 
  436                                 err = fuse_vnode_setsize(vp,
  437                                                          uio->uio_offset + n);
  438                                 if (err) {
  439                                         brelse(bp);
  440                                         break;
  441                                 }
  442                                 save = bp->b_flags & B_CACHE;
  443                                 bcount += n;
  444                                 allocbuf(bp, bcount);
  445                                 bp->b_flags |= save;
  446                         }
  447                 } else {
  448                         /*
  449                          * Obtain the locked cache block first, and then
  450                          * adjust the file's size as appropriate.
  451                          */
  452                         bcount = on + n;
  453                         if ((off_t)lbn * biosize + bcount < fvdat->filesize) {
  454                                 if ((off_t)(lbn + 1) * biosize < fvdat->filesize)
  455                                         bcount = biosize;
  456                                 else
  457                                         bcount = fvdat->filesize - 
  458                                           (off_t)lbn *biosize;
  459                         }
  460                         FS_DEBUG("getting block from OS, bcount %d\n", bcount);
  461                         bp = getblk(vp, lbn, bcount, PCATCH, 0, 0);
  462                         if (bp && uio->uio_offset + n > fvdat->filesize) {
  463                                 err = fuse_vnode_setsize(vp,
  464                                                          uio->uio_offset + n);
  465                                 if (err) {
  466                                         brelse(bp);
  467                                         break;
  468                                 }
  469                         }
  470                 }
  471 
  472                 if (!bp) {
  473                         err = EINTR;
  474                         break;
  475                 }
  476                 /*
  477                  * Issue a READ if B_CACHE is not set.  In special-append
  478                  * mode, B_CACHE is based on the buffer prior to the write
  479                  * op and is typically set, avoiding the read.  If a read
  480                  * is required in special append mode, the server will
  481                  * probably send us a short-read since we extended the file
  482                  * on our end, resulting in b_resid == 0 and, thusly,
  483                  * B_CACHE getting set.
  484                  *
  485                  * We can also avoid issuing the read if the write covers
  486                  * the entire buffer.  We have to make sure the buffer state
  487                  * is reasonable in this case since we will not be initiating
  488                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
  489                  * more information.
  490                  *
  491                  * B_CACHE may also be set due to the buffer being cached
  492                  * normally.
  493                  */
  494 
  495                 if (on == 0 && n == bcount) {
  496                         bp->b_flags |= B_CACHE;
  497                         bp->b_flags &= ~B_INVAL;
  498                         bp->b_ioflags &= ~BIO_ERROR;
  499                 }
  500                 if ((bp->b_flags & B_CACHE) == 0) {
  501                         bp->b_iocmd = BIO_READ;
  502                         vfs_busy_pages(bp, 0);
  503                         fuse_io_strategy(vp, bp);
  504                         if ((err = bp->b_error)) {
  505                                 brelse(bp);
  506                                 break;
  507                         }
  508                 }
  509                 if (bp->b_wcred == NOCRED)
  510                         bp->b_wcred = crhold(cred);
  511 
  512                 /*
  513                  * If dirtyend exceeds file size, chop it down.  This should
  514                  * not normally occur but there is an append race where it
  515                  * might occur XXX, so we log it.
  516                  *
  517                  * If the chopping creates a reverse-indexed or degenerate
  518                  * situation with dirtyoff/end, we 0 both of them.
  519                  */
  520 
  521                 if (bp->b_dirtyend > bcount) {
  522                         FS_DEBUG("FUSE append race @%lx:%d\n",
  523                             (long)bp->b_blkno * biosize,
  524                             bp->b_dirtyend - bcount);
  525                         bp->b_dirtyend = bcount;
  526                 }
  527                 if (bp->b_dirtyoff >= bp->b_dirtyend)
  528                         bp->b_dirtyoff = bp->b_dirtyend = 0;
  529 
  530                 /*
  531                  * If the new write will leave a contiguous dirty
  532                  * area, just update the b_dirtyoff and b_dirtyend,
  533                  * otherwise force a write rpc of the old dirty area.
  534                  *
  535                  * While it is possible to merge discontiguous writes due to
  536                  * our having a B_CACHE buffer ( and thus valid read data
  537                  * for the hole), we don't because it could lead to
  538                  * significant cache coherency problems with multiple clients,
  539                  * especially if locking is implemented later on.
  540                  *
  541                  * as an optimization we could theoretically maintain
  542                  * a linked list of discontinuous areas, but we would still
  543                  * have to commit them separately so there isn't much
  544                  * advantage to it except perhaps a bit of asynchronization.
  545                  */
  546 
  547                 if (bp->b_dirtyend > 0 &&
  548                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
  549                         /*
  550                          * Yes, we mean it. Write out everything to "storage"
  551                          * immediately, without hesitation. (Apart from other
  552                          * reasons: the only way to know if a write is valid
  553                          * if its actually written out.)
  554                          */
  555                         bwrite(bp);
  556                         if (bp->b_error == EINTR) {
  557                                 err = EINTR;
  558                                 break;
  559                         }
  560                         goto again;
  561                 }
  562                 err = uiomove((char *)bp->b_data + on, n, uio);
  563 
  564                 /*
  565                  * Since this block is being modified, it must be written
  566                  * again and not just committed.  Since write clustering does
  567                  * not work for the stage 1 data write, only the stage 2
  568                  * commit rpc, we have to clear B_CLUSTEROK as well.
  569                  */
  570                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
  571 
  572                 if (err) {
  573                         bp->b_ioflags |= BIO_ERROR;
  574                         bp->b_error = err;
  575                         brelse(bp);
  576                         break;
  577                 }
  578                 /*
  579                  * Only update dirtyoff/dirtyend if not a degenerate
  580                  * condition.
  581                  */
  582                 if (n) {
  583                         if (bp->b_dirtyend > 0) {
  584                                 bp->b_dirtyoff = MIN(on, bp->b_dirtyoff);
  585                                 bp->b_dirtyend = MAX((on + n), bp->b_dirtyend);
  586                         } else {
  587                                 bp->b_dirtyoff = on;
  588                                 bp->b_dirtyend = on + n;
  589                         }
  590                         vfs_bio_set_valid(bp, on, n);
  591                 }
  592                 err = bwrite(bp);
  593                 if (err)
  594                         break;
  595         } while (uio->uio_resid > 0 && n > 0);
  596 
  597         if (fuse_sync_resize && (fvdat->flag & FN_SIZECHANGE) != 0)
  598                 fuse_vnode_savesize(vp, cred);
  599 
  600         return (err);
  601 }
  602 
  603 int
  604 fuse_io_strategy(struct vnode *vp, struct buf *bp)
  605 {
  606         struct fuse_filehandle *fufh;
  607         struct fuse_vnode_data *fvdat = VTOFUD(vp);
  608         struct ucred *cred;
  609         struct uio *uiop;
  610         struct uio uio;
  611         struct iovec io;
  612         int error = 0;
  613 
  614         const int biosize = fuse_iosize(vp);
  615 
  616         MPASS(vp->v_type == VREG || vp->v_type == VDIR);
  617         MPASS(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE);
  618         FS_DEBUG("inode=%ju offset=%jd resid=%ld\n",
  619             (uintmax_t)VTOI(vp), (intmax_t)(((off_t)bp->b_blkno) * biosize),
  620             bp->b_bcount);
  621 
  622         error = fuse_filehandle_getrw(vp,
  623             (bp->b_iocmd == BIO_READ) ? FUFH_RDONLY : FUFH_WRONLY, &fufh);
  624         if (error) {
  625                 printf("FUSE: strategy: filehandles are closed\n");
  626                 bp->b_ioflags |= BIO_ERROR;
  627                 bp->b_error = error;
  628                 return (error);
  629         }
  630         cred = bp->b_iocmd == BIO_READ ? bp->b_rcred : bp->b_wcred;
  631 
  632         uiop = &uio;
  633         uiop->uio_iov = &io;
  634         uiop->uio_iovcnt = 1;
  635         uiop->uio_segflg = UIO_SYSSPACE;
  636         uiop->uio_td = curthread;
  637 
  638         /*
  639          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
  640          * do this here so we do not have to do it in all the code that
  641          * calls us.
  642          */
  643         bp->b_flags &= ~B_INVAL;
  644         bp->b_ioflags &= ~BIO_ERROR;
  645 
  646         KASSERT(!(bp->b_flags & B_DONE),
  647             ("fuse_io_strategy: bp %p already marked done", bp));
  648         if (bp->b_iocmd == BIO_READ) {
  649                 io.iov_len = uiop->uio_resid = bp->b_bcount;
  650                 io.iov_base = bp->b_data;
  651                 uiop->uio_rw = UIO_READ;
  652 
  653                 uiop->uio_offset = ((off_t)bp->b_blkno) * biosize;
  654                 error = fuse_read_directbackend(vp, uiop, cred, fufh);
  655 
  656                 if ((!error && uiop->uio_resid) ||
  657                     (fsess_opt_brokenio(vnode_mount(vp)) && error == EIO &&
  658                     uiop->uio_offset < fvdat->filesize && fvdat->filesize > 0 &&
  659                     uiop->uio_offset >= fvdat->cached_attrs.va_size)) {
  660                         /*
  661                          * If we had a short read with no error, we must have
  662                          * hit a file hole.  We should zero-fill the remainder.
  663                          * This can also occur if the server hits the file EOF.
  664                          *
  665                          * Holes used to be able to occur due to pending
  666                          * writes, but that is not possible any longer.
  667                          */
  668                         int nread = bp->b_bcount - uiop->uio_resid;
  669                         int left = uiop->uio_resid;
  670 
  671                         if (error != 0) {
  672                                 printf("FUSE: Fix broken io: offset %ju, "
  673                                        " resid %zd, file size %ju/%ju\n", 
  674                                        (uintmax_t)uiop->uio_offset,
  675                                     uiop->uio_resid, fvdat->filesize,
  676                                     fvdat->cached_attrs.va_size);
  677                                 error = 0;
  678                         }
  679                         if (left > 0)
  680                                 bzero((char *)bp->b_data + nread, left);
  681                         uiop->uio_resid = 0;
  682                 }
  683                 if (error) {
  684                         bp->b_ioflags |= BIO_ERROR;
  685                         bp->b_error = error;
  686                 }
  687         } else {
  688                 /*
  689                  * If we only need to commit, try to commit
  690                  */
  691                 if (bp->b_flags & B_NEEDCOMMIT) {
  692                         FS_DEBUG("write: B_NEEDCOMMIT flags set\n");
  693                 }
  694                 /*
  695                  * Setup for actual write
  696                  */
  697                 if ((off_t)bp->b_blkno * biosize + bp->b_dirtyend > 
  698                     fvdat->filesize)
  699                         bp->b_dirtyend = fvdat->filesize - 
  700                                 (off_t)bp->b_blkno * biosize;
  701 
  702                 if (bp->b_dirtyend > bp->b_dirtyoff) {
  703                         io.iov_len = uiop->uio_resid = bp->b_dirtyend
  704                             - bp->b_dirtyoff;
  705                         uiop->uio_offset = (off_t)bp->b_blkno * biosize
  706                             + bp->b_dirtyoff;
  707                         io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
  708                         uiop->uio_rw = UIO_WRITE;
  709 
  710                         error = fuse_write_directbackend(vp, uiop, cred, fufh, 0);
  711 
  712                         if (error == EINTR || error == ETIMEDOUT
  713                             || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
  714 
  715                                 bp->b_flags &= ~(B_INVAL | B_NOCACHE);
  716                                 if ((bp->b_flags & B_PAGING) == 0) {
  717                                         bdirty(bp);
  718                                         bp->b_flags &= ~B_DONE;
  719                                 }
  720                                 if ((error == EINTR || error == ETIMEDOUT) &&
  721                                     (bp->b_flags & B_ASYNC) == 0)
  722                                         bp->b_flags |= B_EINTR;
  723                         } else {
  724                                 if (error) {
  725                                         bp->b_ioflags |= BIO_ERROR;
  726                                         bp->b_flags |= B_INVAL;
  727                                         bp->b_error = error;
  728                                 }
  729                                 bp->b_dirtyoff = bp->b_dirtyend = 0;
  730                         }
  731                 } else {
  732                         bp->b_resid = 0;
  733                         bufdone(bp);
  734                         return (0);
  735                 }
  736         }
  737         bp->b_resid = uiop->uio_resid;
  738         bufdone(bp);
  739         return (error);
  740 }
  741 
  742 int
  743 fuse_io_flushbuf(struct vnode *vp, int waitfor, struct thread *td)
  744 {
  745         struct vop_fsync_args a = {
  746                 .a_vp = vp,
  747                 .a_waitfor = waitfor,
  748                 .a_td = td,
  749         };
  750 
  751         return (vop_stdfsync(&a));
  752 }
  753 
  754 /*
  755  * Flush and invalidate all dirty buffers. If another process is already
  756  * doing the flush, just wait for completion.
  757  */
  758 int
  759 fuse_io_invalbuf(struct vnode *vp, struct thread *td)
  760 {
  761         struct fuse_vnode_data *fvdat = VTOFUD(vp);
  762         int error = 0;
  763 
  764         if (vp->v_iflag & VI_DOOMED)
  765                 return 0;
  766 
  767         ASSERT_VOP_ELOCKED(vp, "fuse_io_invalbuf");
  768 
  769         while (fvdat->flag & FN_FLUSHINPROG) {
  770                 struct proc *p = td->td_proc;
  771 
  772                 if (vp->v_mount->mnt_kern_flag & MNTK_UNMOUNTF)
  773                         return EIO;
  774                 fvdat->flag |= FN_FLUSHWANT;
  775                 tsleep(&fvdat->flag, PRIBIO + 2, "fusevinv", 2 * hz);
  776                 error = 0;
  777                 if (p != NULL) {
  778                         PROC_LOCK(p);
  779                         if (SIGNOTEMPTY(p->p_siglist) ||
  780                             SIGNOTEMPTY(td->td_siglist))
  781                                 error = EINTR;
  782                         PROC_UNLOCK(p);
  783                 }
  784                 if (error == EINTR)
  785                         return EINTR;
  786         }
  787         fvdat->flag |= FN_FLUSHINPROG;
  788 
  789         if (vp->v_bufobj.bo_object != NULL) {
  790                 VM_OBJECT_WLOCK(vp->v_bufobj.bo_object);
  791                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
  792                 VM_OBJECT_WUNLOCK(vp->v_bufobj.bo_object);
  793         }
  794         error = vinvalbuf(vp, V_SAVE, PCATCH, 0);
  795         while (error) {
  796                 if (error == ERESTART || error == EINTR) {
  797                         fvdat->flag &= ~FN_FLUSHINPROG;
  798                         if (fvdat->flag & FN_FLUSHWANT) {
  799                                 fvdat->flag &= ~FN_FLUSHWANT;
  800                                 wakeup(&fvdat->flag);
  801                         }
  802                         return EINTR;
  803                 }
  804                 error = vinvalbuf(vp, V_SAVE, PCATCH, 0);
  805         }
  806         fvdat->flag &= ~FN_FLUSHINPROG;
  807         if (fvdat->flag & FN_FLUSHWANT) {
  808                 fvdat->flag &= ~FN_FLUSHWANT;
  809                 wakeup(&fvdat->flag);
  810         }
  811         return (error);
  812 }

Cache object: debbc19aa8ca0d7a5c1415d021bf82de


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