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

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    1 /*-
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Rick Macklem at The University of Guelph.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 4. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  *      @(#)nfs_bio.c   8.9 (Berkeley) 3/30/95
   33  */
   34 
   35 #include <sys/cdefs.h>
   36 __FBSDID("$FreeBSD: releng/11.0/sys/fs/nfsclient/nfs_clbio.c 303909 2016-08-10 12:53:30Z kib $");
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/bio.h>
   41 #include <sys/buf.h>
   42 #include <sys/kernel.h>
   43 #include <sys/mount.h>
   44 #include <sys/rwlock.h>
   45 #include <sys/vmmeter.h>
   46 #include <sys/vnode.h>
   47 
   48 #include <vm/vm.h>
   49 #include <vm/vm_param.h>
   50 #include <vm/vm_extern.h>
   51 #include <vm/vm_page.h>
   52 #include <vm/vm_object.h>
   53 #include <vm/vm_pager.h>
   54 #include <vm/vnode_pager.h>
   55 
   56 #include <fs/nfs/nfsport.h>
   57 #include <fs/nfsclient/nfsmount.h>
   58 #include <fs/nfsclient/nfs.h>
   59 #include <fs/nfsclient/nfsnode.h>
   60 #include <fs/nfsclient/nfs_kdtrace.h>
   61 
   62 extern int newnfs_directio_allow_mmap;
   63 extern struct nfsstats newnfsstats;
   64 extern struct mtx ncl_iod_mutex;
   65 extern int ncl_numasync;
   66 extern enum nfsiod_state ncl_iodwant[NFS_MAXASYNCDAEMON];
   67 extern struct nfsmount *ncl_iodmount[NFS_MAXASYNCDAEMON];
   68 extern int newnfs_directio_enable;
   69 extern int nfs_keep_dirty_on_error;
   70 
   71 int ncl_pbuf_freecnt = -1;      /* start out unlimited */
   72 
   73 static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
   74     struct thread *td);
   75 static int nfs_directio_write(struct vnode *vp, struct uio *uiop,
   76     struct ucred *cred, int ioflag);
   77 
   78 /*
   79  * Vnode op for VM getpages.
   80  */
   81 int
   82 ncl_getpages(struct vop_getpages_args *ap)
   83 {
   84         int i, error, nextoff, size, toff, count, npages;
   85         struct uio uio;
   86         struct iovec iov;
   87         vm_offset_t kva;
   88         struct buf *bp;
   89         struct vnode *vp;
   90         struct thread *td;
   91         struct ucred *cred;
   92         struct nfsmount *nmp;
   93         vm_object_t object;
   94         vm_page_t *pages;
   95         struct nfsnode *np;
   96 
   97         vp = ap->a_vp;
   98         np = VTONFS(vp);
   99         td = curthread;                         /* XXX */
  100         cred = curthread->td_ucred;             /* XXX */
  101         nmp = VFSTONFS(vp->v_mount);
  102         pages = ap->a_m;
  103         npages = ap->a_count;
  104 
  105         if ((object = vp->v_object) == NULL) {
  106                 printf("ncl_getpages: called with non-merged cache vnode\n");
  107                 return (VM_PAGER_ERROR);
  108         }
  109 
  110         if (newnfs_directio_enable && !newnfs_directio_allow_mmap) {
  111                 mtx_lock(&np->n_mtx);
  112                 if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  113                         mtx_unlock(&np->n_mtx);
  114                         printf("ncl_getpages: called on non-cacheable vnode\n");
  115                         return (VM_PAGER_ERROR);
  116                 } else
  117                         mtx_unlock(&np->n_mtx);
  118         }
  119 
  120         mtx_lock(&nmp->nm_mtx);
  121         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  122             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  123                 mtx_unlock(&nmp->nm_mtx);
  124                 /* We'll never get here for v4, because we always have fsinfo */
  125                 (void)ncl_fsinfo(nmp, vp, cred, td);
  126         } else
  127                 mtx_unlock(&nmp->nm_mtx);
  128 
  129         /*
  130          * If the requested page is partially valid, just return it and
  131          * allow the pager to zero-out the blanks.  Partially valid pages
  132          * can only occur at the file EOF.
  133          *
  134          * XXXGL: is that true for NFS, where short read can occur???
  135          */
  136         VM_OBJECT_WLOCK(object);
  137         if (pages[npages - 1]->valid != 0 && --npages == 0)
  138                 goto out;
  139         VM_OBJECT_WUNLOCK(object);
  140 
  141         /*
  142          * We use only the kva address for the buffer, but this is extremely
  143          * convenient and fast.
  144          */
  145         bp = getpbuf(&ncl_pbuf_freecnt);
  146 
  147         kva = (vm_offset_t) bp->b_data;
  148         pmap_qenter(kva, pages, npages);
  149         PCPU_INC(cnt.v_vnodein);
  150         PCPU_ADD(cnt.v_vnodepgsin, npages);
  151 
  152         count = npages << PAGE_SHIFT;
  153         iov.iov_base = (caddr_t) kva;
  154         iov.iov_len = count;
  155         uio.uio_iov = &iov;
  156         uio.uio_iovcnt = 1;
  157         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  158         uio.uio_resid = count;
  159         uio.uio_segflg = UIO_SYSSPACE;
  160         uio.uio_rw = UIO_READ;
  161         uio.uio_td = td;
  162 
  163         error = ncl_readrpc(vp, &uio, cred);
  164         pmap_qremove(kva, npages);
  165 
  166         relpbuf(bp, &ncl_pbuf_freecnt);
  167 
  168         if (error && (uio.uio_resid == count)) {
  169                 printf("ncl_getpages: error %d\n", error);
  170                 return (VM_PAGER_ERROR);
  171         }
  172 
  173         /*
  174          * Calculate the number of bytes read and validate only that number
  175          * of bytes.  Note that due to pending writes, size may be 0.  This
  176          * does not mean that the remaining data is invalid!
  177          */
  178 
  179         size = count - uio.uio_resid;
  180         VM_OBJECT_WLOCK(object);
  181         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  182                 vm_page_t m;
  183                 nextoff = toff + PAGE_SIZE;
  184                 m = pages[i];
  185 
  186                 if (nextoff <= size) {
  187                         /*
  188                          * Read operation filled an entire page
  189                          */
  190                         m->valid = VM_PAGE_BITS_ALL;
  191                         KASSERT(m->dirty == 0,
  192                             ("nfs_getpages: page %p is dirty", m));
  193                 } else if (size > toff) {
  194                         /*
  195                          * Read operation filled a partial page.
  196                          */
  197                         m->valid = 0;
  198                         vm_page_set_valid_range(m, 0, size - toff);
  199                         KASSERT(m->dirty == 0,
  200                             ("nfs_getpages: page %p is dirty", m));
  201                 } else {
  202                         /*
  203                          * Read operation was short.  If no error
  204                          * occurred we may have hit a zero-fill
  205                          * section.  We leave valid set to 0, and page
  206                          * is freed by vm_page_readahead_finish() if
  207                          * its index is not equal to requested, or
  208                          * page is zeroed and set valid by
  209                          * vm_pager_get_pages() for requested page.
  210                          */
  211                         ;
  212                 }
  213         }
  214 out:
  215         VM_OBJECT_WUNLOCK(object);
  216         if (ap->a_rbehind)
  217                 *ap->a_rbehind = 0;
  218         if (ap->a_rahead)
  219                 *ap->a_rahead = 0;
  220         return (VM_PAGER_OK);
  221 }
  222 
  223 /*
  224  * Vnode op for VM putpages.
  225  */
  226 int
  227 ncl_putpages(struct vop_putpages_args *ap)
  228 {
  229         struct uio uio;
  230         struct iovec iov;
  231         vm_offset_t kva;
  232         struct buf *bp;
  233         int iomode, must_commit, i, error, npages, count;
  234         off_t offset;
  235         int *rtvals;
  236         struct vnode *vp;
  237         struct thread *td;
  238         struct ucred *cred;
  239         struct nfsmount *nmp;
  240         struct nfsnode *np;
  241         vm_page_t *pages;
  242 
  243         vp = ap->a_vp;
  244         np = VTONFS(vp);
  245         td = curthread;                         /* XXX */
  246         /* Set the cred to n_writecred for the write rpcs. */
  247         if (np->n_writecred != NULL)
  248                 cred = crhold(np->n_writecred);
  249         else
  250                 cred = crhold(curthread->td_ucred);     /* XXX */
  251         nmp = VFSTONFS(vp->v_mount);
  252         pages = ap->a_m;
  253         count = ap->a_count;
  254         rtvals = ap->a_rtvals;
  255         npages = btoc(count);
  256         offset = IDX_TO_OFF(pages[0]->pindex);
  257 
  258         mtx_lock(&nmp->nm_mtx);
  259         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  260             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  261                 mtx_unlock(&nmp->nm_mtx);
  262                 (void)ncl_fsinfo(nmp, vp, cred, td);
  263         } else
  264                 mtx_unlock(&nmp->nm_mtx);
  265 
  266         mtx_lock(&np->n_mtx);
  267         if (newnfs_directio_enable && !newnfs_directio_allow_mmap &&
  268             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  269                 mtx_unlock(&np->n_mtx);
  270                 printf("ncl_putpages: called on noncache-able vnode\n");
  271                 mtx_lock(&np->n_mtx);
  272         }
  273 
  274         for (i = 0; i < npages; i++)
  275                 rtvals[i] = VM_PAGER_ERROR;
  276 
  277         /*
  278          * When putting pages, do not extend file past EOF.
  279          */
  280         if (offset + count > np->n_size) {
  281                 count = np->n_size - offset;
  282                 if (count < 0)
  283                         count = 0;
  284         }
  285         mtx_unlock(&np->n_mtx);
  286 
  287         /*
  288          * We use only the kva address for the buffer, but this is extremely
  289          * convenient and fast.
  290          */
  291         bp = getpbuf(&ncl_pbuf_freecnt);
  292 
  293         kva = (vm_offset_t) bp->b_data;
  294         pmap_qenter(kva, pages, npages);
  295         PCPU_INC(cnt.v_vnodeout);
  296         PCPU_ADD(cnt.v_vnodepgsout, count);
  297 
  298         iov.iov_base = (caddr_t) kva;
  299         iov.iov_len = count;
  300         uio.uio_iov = &iov;
  301         uio.uio_iovcnt = 1;
  302         uio.uio_offset = offset;
  303         uio.uio_resid = count;
  304         uio.uio_segflg = UIO_SYSSPACE;
  305         uio.uio_rw = UIO_WRITE;
  306         uio.uio_td = td;
  307 
  308         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  309             iomode = NFSWRITE_UNSTABLE;
  310         else
  311             iomode = NFSWRITE_FILESYNC;
  312 
  313         error = ncl_writerpc(vp, &uio, cred, &iomode, &must_commit, 0);
  314         crfree(cred);
  315 
  316         pmap_qremove(kva, npages);
  317         relpbuf(bp, &ncl_pbuf_freecnt);
  318 
  319         if (error == 0 || !nfs_keep_dirty_on_error) {
  320                 vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
  321                 if (must_commit)
  322                         ncl_clearcommit(vp->v_mount);
  323         }
  324         return rtvals[0];
  325 }
  326 
  327 /*
  328  * For nfs, cache consistency can only be maintained approximately.
  329  * Although RFC1094 does not specify the criteria, the following is
  330  * believed to be compatible with the reference port.
  331  * For nfs:
  332  * If the file's modify time on the server has changed since the
  333  * last read rpc or you have written to the file,
  334  * you may have lost data cache consistency with the
  335  * server, so flush all of the file's data out of the cache.
  336  * Then force a getattr rpc to ensure that you have up to date
  337  * attributes.
  338  * NB: This implies that cache data can be read when up to
  339  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  340  * attributes this could be forced by setting n_attrstamp to 0 before
  341  * the VOP_GETATTR() call.
  342  */
  343 static inline int
  344 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  345 {
  346         int error = 0;
  347         struct vattr vattr;
  348         struct nfsnode *np = VTONFS(vp);
  349         int old_lock;
  350 
  351         /*
  352          * Grab the exclusive lock before checking whether the cache is
  353          * consistent.
  354          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  355          * But for now, this suffices.
  356          */
  357         old_lock = ncl_upgrade_vnlock(vp);
  358         if (vp->v_iflag & VI_DOOMED) {
  359                 ncl_downgrade_vnlock(vp, old_lock);
  360                 return (EBADF);
  361         }
  362 
  363         mtx_lock(&np->n_mtx);
  364         if (np->n_flag & NMODIFIED) {
  365                 mtx_unlock(&np->n_mtx);
  366                 if (vp->v_type != VREG) {
  367                         if (vp->v_type != VDIR)
  368                                 panic("nfs: bioread, not dir");
  369                         ncl_invaldir(vp);
  370                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  371                         if (error)
  372                                 goto out;
  373                 }
  374                 np->n_attrstamp = 0;
  375                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  376                 error = VOP_GETATTR(vp, &vattr, cred);
  377                 if (error)
  378                         goto out;
  379                 mtx_lock(&np->n_mtx);
  380                 np->n_mtime = vattr.va_mtime;
  381                 mtx_unlock(&np->n_mtx);
  382         } else {
  383                 mtx_unlock(&np->n_mtx);
  384                 error = VOP_GETATTR(vp, &vattr, cred);
  385                 if (error)
  386                         return (error);
  387                 mtx_lock(&np->n_mtx);
  388                 if ((np->n_flag & NSIZECHANGED)
  389                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  390                         mtx_unlock(&np->n_mtx);
  391                         if (vp->v_type == VDIR)
  392                                 ncl_invaldir(vp);
  393                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  394                         if (error)
  395                                 goto out;
  396                         mtx_lock(&np->n_mtx);
  397                         np->n_mtime = vattr.va_mtime;
  398                         np->n_flag &= ~NSIZECHANGED;
  399                 }
  400                 mtx_unlock(&np->n_mtx);
  401         }
  402 out:
  403         ncl_downgrade_vnlock(vp, old_lock);
  404         return error;
  405 }
  406 
  407 /*
  408  * Vnode op for read using bio
  409  */
  410 int
  411 ncl_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  412 {
  413         struct nfsnode *np = VTONFS(vp);
  414         int biosize, i;
  415         struct buf *bp, *rabp;
  416         struct thread *td;
  417         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  418         daddr_t lbn, rabn;
  419         int bcount;
  420         int seqcount;
  421         int nra, error = 0, n = 0, on = 0;
  422         off_t tmp_off;
  423 
  424         KASSERT(uio->uio_rw == UIO_READ, ("ncl_read mode"));
  425         if (uio->uio_resid == 0)
  426                 return (0);
  427         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  428                 return (EINVAL);
  429         td = uio->uio_td;
  430 
  431         mtx_lock(&nmp->nm_mtx);
  432         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  433             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  434                 mtx_unlock(&nmp->nm_mtx);
  435                 (void)ncl_fsinfo(nmp, vp, cred, td);
  436                 mtx_lock(&nmp->nm_mtx);
  437         }
  438         if (nmp->nm_rsize == 0 || nmp->nm_readdirsize == 0)
  439                 (void) newnfs_iosize(nmp);
  440 
  441         tmp_off = uio->uio_offset + uio->uio_resid;
  442         if (vp->v_type != VDIR &&
  443             (tmp_off > nmp->nm_maxfilesize || tmp_off < uio->uio_offset)) {
  444                 mtx_unlock(&nmp->nm_mtx);
  445                 return (EFBIG);
  446         }
  447         mtx_unlock(&nmp->nm_mtx);
  448 
  449         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  450                 /* No caching/ no readaheads. Just read data into the user buffer */
  451                 return ncl_readrpc(vp, uio, cred);
  452 
  453         biosize = vp->v_bufobj.bo_bsize;
  454         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  455 
  456         error = nfs_bioread_check_cons(vp, td, cred);
  457         if (error)
  458                 return error;
  459 
  460         do {
  461             u_quad_t nsize;
  462 
  463             mtx_lock(&np->n_mtx);
  464             nsize = np->n_size;
  465             mtx_unlock(&np->n_mtx);
  466 
  467             switch (vp->v_type) {
  468             case VREG:
  469                 NFSINCRGLOBAL(newnfsstats.biocache_reads);
  470                 lbn = uio->uio_offset / biosize;
  471                 on = uio->uio_offset - (lbn * biosize);
  472 
  473                 /*
  474                  * Start the read ahead(s), as required.
  475                  */
  476                 if (nmp->nm_readahead > 0) {
  477                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  478                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  479                         rabn = lbn + 1 + nra;
  480                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  481                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  482                             if (!rabp) {
  483                                 error = newnfs_sigintr(nmp, td);
  484                                 return (error ? error : EINTR);
  485                             }
  486                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  487                                 rabp->b_flags |= B_ASYNC;
  488                                 rabp->b_iocmd = BIO_READ;
  489                                 vfs_busy_pages(rabp, 0);
  490                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  491                                     rabp->b_flags |= B_INVAL;
  492                                     rabp->b_ioflags |= BIO_ERROR;
  493                                     vfs_unbusy_pages(rabp);
  494                                     brelse(rabp);
  495                                     break;
  496                                 }
  497                             } else {
  498                                 brelse(rabp);
  499                             }
  500                         }
  501                     }
  502                 }
  503 
  504                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  505                 bcount = biosize;
  506                 if ((off_t)lbn * biosize >= nsize) {
  507                         bcount = 0;
  508                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  509                         bcount = nsize - (off_t)lbn * biosize;
  510                 }
  511                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  512 
  513                 if (!bp) {
  514                         error = newnfs_sigintr(nmp, td);
  515                         return (error ? error : EINTR);
  516                 }
  517 
  518                 /*
  519                  * If B_CACHE is not set, we must issue the read.  If this
  520                  * fails, we return an error.
  521                  */
  522 
  523                 if ((bp->b_flags & B_CACHE) == 0) {
  524                     bp->b_iocmd = BIO_READ;
  525                     vfs_busy_pages(bp, 0);
  526                     error = ncl_doio(vp, bp, cred, td, 0);
  527                     if (error) {
  528                         brelse(bp);
  529                         return (error);
  530                     }
  531                 }
  532 
  533                 /*
  534                  * on is the offset into the current bp.  Figure out how many
  535                  * bytes we can copy out of the bp.  Note that bcount is
  536                  * NOT DEV_BSIZE aligned.
  537                  *
  538                  * Then figure out how many bytes we can copy into the uio.
  539                  */
  540 
  541                 n = 0;
  542                 if (on < bcount)
  543                         n = MIN((unsigned)(bcount - on), uio->uio_resid);
  544                 break;
  545             case VLNK:
  546                 NFSINCRGLOBAL(newnfsstats.biocache_readlinks);
  547                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  548                 if (!bp) {
  549                         error = newnfs_sigintr(nmp, td);
  550                         return (error ? error : EINTR);
  551                 }
  552                 if ((bp->b_flags & B_CACHE) == 0) {
  553                     bp->b_iocmd = BIO_READ;
  554                     vfs_busy_pages(bp, 0);
  555                     error = ncl_doio(vp, bp, cred, td, 0);
  556                     if (error) {
  557                         bp->b_ioflags |= BIO_ERROR;
  558                         brelse(bp);
  559                         return (error);
  560                     }
  561                 }
  562                 n = MIN(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  563                 on = 0;
  564                 break;
  565             case VDIR:
  566                 NFSINCRGLOBAL(newnfsstats.biocache_readdirs);
  567                 if (np->n_direofoffset
  568                     && uio->uio_offset >= np->n_direofoffset) {
  569                     return (0);
  570                 }
  571                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  572                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  573                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  574                 if (!bp) {
  575                     error = newnfs_sigintr(nmp, td);
  576                     return (error ? error : EINTR);
  577                 }
  578                 if ((bp->b_flags & B_CACHE) == 0) {
  579                     bp->b_iocmd = BIO_READ;
  580                     vfs_busy_pages(bp, 0);
  581                     error = ncl_doio(vp, bp, cred, td, 0);
  582                     if (error) {
  583                             brelse(bp);
  584                     }
  585                     while (error == NFSERR_BAD_COOKIE) {
  586                         ncl_invaldir(vp);
  587                         error = ncl_vinvalbuf(vp, 0, td, 1);
  588                         /*
  589                          * Yuck! The directory has been modified on the
  590                          * server. The only way to get the block is by
  591                          * reading from the beginning to get all the
  592                          * offset cookies.
  593                          *
  594                          * Leave the last bp intact unless there is an error.
  595                          * Loop back up to the while if the error is another
  596                          * NFSERR_BAD_COOKIE (double yuch!).
  597                          */
  598                         for (i = 0; i <= lbn && !error; i++) {
  599                             if (np->n_direofoffset
  600                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  601                                     return (0);
  602                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  603                             if (!bp) {
  604                                 error = newnfs_sigintr(nmp, td);
  605                                 return (error ? error : EINTR);
  606                             }
  607                             if ((bp->b_flags & B_CACHE) == 0) {
  608                                     bp->b_iocmd = BIO_READ;
  609                                     vfs_busy_pages(bp, 0);
  610                                     error = ncl_doio(vp, bp, cred, td, 0);
  611                                     /*
  612                                      * no error + B_INVAL == directory EOF,
  613                                      * use the block.
  614                                      */
  615                                     if (error == 0 && (bp->b_flags & B_INVAL))
  616                                             break;
  617                             }
  618                             /*
  619                              * An error will throw away the block and the
  620                              * for loop will break out.  If no error and this
  621                              * is not the block we want, we throw away the
  622                              * block and go for the next one via the for loop.
  623                              */
  624                             if (error || i < lbn)
  625                                     brelse(bp);
  626                         }
  627                     }
  628                     /*
  629                      * The above while is repeated if we hit another cookie
  630                      * error.  If we hit an error and it wasn't a cookie error,
  631                      * we give up.
  632                      */
  633                     if (error)
  634                             return (error);
  635                 }
  636 
  637                 /*
  638                  * If not eof and read aheads are enabled, start one.
  639                  * (You need the current block first, so that you have the
  640                  *  directory offset cookie of the next block.)
  641                  */
  642                 if (nmp->nm_readahead > 0 &&
  643                     (bp->b_flags & B_INVAL) == 0 &&
  644                     (np->n_direofoffset == 0 ||
  645                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  646                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  647                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  648                         if (rabp) {
  649                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  650                                 rabp->b_flags |= B_ASYNC;
  651                                 rabp->b_iocmd = BIO_READ;
  652                                 vfs_busy_pages(rabp, 0);
  653                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  654                                     rabp->b_flags |= B_INVAL;
  655                                     rabp->b_ioflags |= BIO_ERROR;
  656                                     vfs_unbusy_pages(rabp);
  657                                     brelse(rabp);
  658                                 }
  659                             } else {
  660                                 brelse(rabp);
  661                             }
  662                         }
  663                 }
  664                 /*
  665                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  666                  * chopped for the EOF condition, we cannot tell how large
  667                  * NFS directories are going to be until we hit EOF.  So
  668                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  669                  * it just so happens that b_resid will effectively chop it
  670                  * to EOF.  *BUT* this information is lost if the buffer goes
  671                  * away and is reconstituted into a B_CACHE state ( due to
  672                  * being VMIO ) later.  So we keep track of the directory eof
  673                  * in np->n_direofoffset and chop it off as an extra step
  674                  * right here.
  675                  */
  676                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  677                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  678                         n = np->n_direofoffset - uio->uio_offset;
  679                 break;
  680             default:
  681                 printf(" ncl_bioread: type %x unexpected\n", vp->v_type);
  682                 bp = NULL;
  683                 break;
  684             }
  685 
  686             if (n > 0) {
  687                     error = vn_io_fault_uiomove(bp->b_data + on, (int)n, uio);
  688             }
  689             if (vp->v_type == VLNK)
  690                 n = 0;
  691             if (bp != NULL)
  692                 brelse(bp);
  693         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  694         return (error);
  695 }
  696 
  697 /*
  698  * The NFS write path cannot handle iovecs with len > 1. So we need to
  699  * break up iovecs accordingly (restricting them to wsize).
  700  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf).
  701  * For the ASYNC case, 2 copies are needed. The first a copy from the
  702  * user buffer to a staging buffer and then a second copy from the staging
  703  * buffer to mbufs. This can be optimized by copying from the user buffer
  704  * directly into mbufs and passing the chain down, but that requires a
  705  * fair amount of re-working of the relevant codepaths (and can be done
  706  * later).
  707  */
  708 static int
  709 nfs_directio_write(vp, uiop, cred, ioflag)
  710         struct vnode *vp;
  711         struct uio *uiop;
  712         struct ucred *cred;
  713         int ioflag;
  714 {
  715         int error;
  716         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  717         struct thread *td = uiop->uio_td;
  718         int size;
  719         int wsize;
  720 
  721         mtx_lock(&nmp->nm_mtx);
  722         wsize = nmp->nm_wsize;
  723         mtx_unlock(&nmp->nm_mtx);
  724         if (ioflag & IO_SYNC) {
  725                 int iomode, must_commit;
  726                 struct uio uio;
  727                 struct iovec iov;
  728 do_sync:
  729                 while (uiop->uio_resid > 0) {
  730                         size = MIN(uiop->uio_resid, wsize);
  731                         size = MIN(uiop->uio_iov->iov_len, size);
  732                         iov.iov_base = uiop->uio_iov->iov_base;
  733                         iov.iov_len = size;
  734                         uio.uio_iov = &iov;
  735                         uio.uio_iovcnt = 1;
  736                         uio.uio_offset = uiop->uio_offset;
  737                         uio.uio_resid = size;
  738                         uio.uio_segflg = UIO_USERSPACE;
  739                         uio.uio_rw = UIO_WRITE;
  740                         uio.uio_td = td;
  741                         iomode = NFSWRITE_FILESYNC;
  742                         error = ncl_writerpc(vp, &uio, cred, &iomode,
  743                             &must_commit, 0);
  744                         KASSERT((must_commit == 0),
  745                                 ("ncl_directio_write: Did not commit write"));
  746                         if (error)
  747                                 return (error);
  748                         uiop->uio_offset += size;
  749                         uiop->uio_resid -= size;
  750                         if (uiop->uio_iov->iov_len <= size) {
  751                                 uiop->uio_iovcnt--;
  752                                 uiop->uio_iov++;
  753                         } else {
  754                                 uiop->uio_iov->iov_base =
  755                                         (char *)uiop->uio_iov->iov_base + size;
  756                                 uiop->uio_iov->iov_len -= size;
  757                         }
  758                 }
  759         } else {
  760                 struct uio *t_uio;
  761                 struct iovec *t_iov;
  762                 struct buf *bp;
  763 
  764                 /*
  765                  * Break up the write into blocksize chunks and hand these
  766                  * over to nfsiod's for write back.
  767                  * Unfortunately, this incurs a copy of the data. Since
  768                  * the user could modify the buffer before the write is
  769                  * initiated.
  770                  *
  771                  * The obvious optimization here is that one of the 2 copies
  772                  * in the async write path can be eliminated by copying the
  773                  * data here directly into mbufs and passing the mbuf chain
  774                  * down. But that will require a fair amount of re-working
  775                  * of the code and can be done if there's enough interest
  776                  * in NFS directio access.
  777                  */
  778                 while (uiop->uio_resid > 0) {
  779                         size = MIN(uiop->uio_resid, wsize);
  780                         size = MIN(uiop->uio_iov->iov_len, size);
  781                         bp = getpbuf(&ncl_pbuf_freecnt);
  782                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  783                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  784                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  785                         t_iov->iov_len = size;
  786                         t_uio->uio_iov = t_iov;
  787                         t_uio->uio_iovcnt = 1;
  788                         t_uio->uio_offset = uiop->uio_offset;
  789                         t_uio->uio_resid = size;
  790                         t_uio->uio_segflg = UIO_SYSSPACE;
  791                         t_uio->uio_rw = UIO_WRITE;
  792                         t_uio->uio_td = td;
  793                         KASSERT(uiop->uio_segflg == UIO_USERSPACE ||
  794                             uiop->uio_segflg == UIO_SYSSPACE,
  795                             ("nfs_directio_write: Bad uio_segflg"));
  796                         if (uiop->uio_segflg == UIO_USERSPACE) {
  797                                 error = copyin(uiop->uio_iov->iov_base,
  798                                     t_iov->iov_base, size);
  799                                 if (error != 0)
  800                                         goto err_free;
  801                         } else
  802                                 /*
  803                                  * UIO_SYSSPACE may never happen, but handle
  804                                  * it just in case it does.
  805                                  */
  806                                 bcopy(uiop->uio_iov->iov_base, t_iov->iov_base,
  807                                     size);
  808                         bp->b_flags |= B_DIRECT;
  809                         bp->b_iocmd = BIO_WRITE;
  810                         if (cred != NOCRED) {
  811                                 crhold(cred);
  812                                 bp->b_wcred = cred;
  813                         } else
  814                                 bp->b_wcred = NOCRED;
  815                         bp->b_caller1 = (void *)t_uio;
  816                         bp->b_vp = vp;
  817                         error = ncl_asyncio(nmp, bp, NOCRED, td);
  818 err_free:
  819                         if (error) {
  820                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  821                                 free(t_iov, M_NFSDIRECTIO);
  822                                 free(t_uio, M_NFSDIRECTIO);
  823                                 bp->b_vp = NULL;
  824                                 relpbuf(bp, &ncl_pbuf_freecnt);
  825                                 if (error == EINTR)
  826                                         return (error);
  827                                 goto do_sync;
  828                         }
  829                         uiop->uio_offset += size;
  830                         uiop->uio_resid -= size;
  831                         if (uiop->uio_iov->iov_len <= size) {
  832                                 uiop->uio_iovcnt--;
  833                                 uiop->uio_iov++;
  834                         } else {
  835                                 uiop->uio_iov->iov_base =
  836                                         (char *)uiop->uio_iov->iov_base + size;
  837                                 uiop->uio_iov->iov_len -= size;
  838                         }
  839                 }
  840         }
  841         return (0);
  842 }
  843 
  844 /*
  845  * Vnode op for write using bio
  846  */
  847 int
  848 ncl_write(struct vop_write_args *ap)
  849 {
  850         int biosize;
  851         struct uio *uio = ap->a_uio;
  852         struct thread *td = uio->uio_td;
  853         struct vnode *vp = ap->a_vp;
  854         struct nfsnode *np = VTONFS(vp);
  855         struct ucred *cred = ap->a_cred;
  856         int ioflag = ap->a_ioflag;
  857         struct buf *bp;
  858         struct vattr vattr;
  859         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  860         daddr_t lbn;
  861         int bcount, noncontig_write, obcount;
  862         int bp_cached, n, on, error = 0, error1, wouldcommit;
  863         size_t orig_resid, local_resid;
  864         off_t orig_size, tmp_off;
  865 
  866         KASSERT(uio->uio_rw == UIO_WRITE, ("ncl_write mode"));
  867         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  868             ("ncl_write proc"));
  869         if (vp->v_type != VREG)
  870                 return (EIO);
  871         mtx_lock(&np->n_mtx);
  872         if (np->n_flag & NWRITEERR) {
  873                 np->n_flag &= ~NWRITEERR;
  874                 mtx_unlock(&np->n_mtx);
  875                 return (np->n_error);
  876         } else
  877                 mtx_unlock(&np->n_mtx);
  878         mtx_lock(&nmp->nm_mtx);
  879         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  880             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  881                 mtx_unlock(&nmp->nm_mtx);
  882                 (void)ncl_fsinfo(nmp, vp, cred, td);
  883                 mtx_lock(&nmp->nm_mtx);
  884         }
  885         if (nmp->nm_wsize == 0)
  886                 (void) newnfs_iosize(nmp);
  887         mtx_unlock(&nmp->nm_mtx);
  888 
  889         /*
  890          * Synchronously flush pending buffers if we are in synchronous
  891          * mode or if we are appending.
  892          */
  893         if (ioflag & (IO_APPEND | IO_SYNC)) {
  894                 mtx_lock(&np->n_mtx);
  895                 if (np->n_flag & NMODIFIED) {
  896                         mtx_unlock(&np->n_mtx);
  897 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  898                         /*
  899                          * Require non-blocking, synchronous writes to
  900                          * dirty files to inform the program it needs
  901                          * to fsync(2) explicitly.
  902                          */
  903                         if (ioflag & IO_NDELAY)
  904                                 return (EAGAIN);
  905 #endif
  906                         np->n_attrstamp = 0;
  907                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  908                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  909                         if (error)
  910                                 return (error);
  911                 } else
  912                         mtx_unlock(&np->n_mtx);
  913         }
  914 
  915         orig_resid = uio->uio_resid;
  916         mtx_lock(&np->n_mtx);
  917         orig_size = np->n_size;
  918         mtx_unlock(&np->n_mtx);
  919 
  920         /*
  921          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  922          * get the append lock.
  923          */
  924         if (ioflag & IO_APPEND) {
  925                 np->n_attrstamp = 0;
  926                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  927                 error = VOP_GETATTR(vp, &vattr, cred);
  928                 if (error)
  929                         return (error);
  930                 mtx_lock(&np->n_mtx);
  931                 uio->uio_offset = np->n_size;
  932                 mtx_unlock(&np->n_mtx);
  933         }
  934 
  935         if (uio->uio_offset < 0)
  936                 return (EINVAL);
  937         tmp_off = uio->uio_offset + uio->uio_resid;
  938         if (tmp_off > nmp->nm_maxfilesize || tmp_off < uio->uio_offset)
  939                 return (EFBIG);
  940         if (uio->uio_resid == 0)
  941                 return (0);
  942 
  943         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  944                 return nfs_directio_write(vp, uio, cred, ioflag);
  945 
  946         /*
  947          * Maybe this should be above the vnode op call, but so long as
  948          * file servers have no limits, i don't think it matters
  949          */
  950         if (vn_rlimit_fsize(vp, uio, td))
  951                 return (EFBIG);
  952 
  953         biosize = vp->v_bufobj.bo_bsize;
  954         /*
  955          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  956          * would exceed the local maximum per-file write commit size when
  957          * combined with those, we must decide whether to flush,
  958          * go synchronous, or return error.  We don't bother checking
  959          * IO_UNIT -- we just make all writes atomic anyway, as there's
  960          * no point optimizing for something that really won't ever happen.
  961          */
  962         wouldcommit = 0;
  963         if (!(ioflag & IO_SYNC)) {
  964                 int nflag;
  965 
  966                 mtx_lock(&np->n_mtx);
  967                 nflag = np->n_flag;
  968                 mtx_unlock(&np->n_mtx);
  969                 if (nflag & NMODIFIED) {
  970                         BO_LOCK(&vp->v_bufobj);
  971                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  972                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  973                                     b_bobufs) {
  974                                         if (bp->b_flags & B_NEEDCOMMIT)
  975                                                 wouldcommit += bp->b_bcount;
  976                                 }
  977                         }
  978                         BO_UNLOCK(&vp->v_bufobj);
  979                 }
  980         }
  981 
  982         do {
  983                 if (!(ioflag & IO_SYNC)) {
  984                         wouldcommit += biosize;
  985                         if (wouldcommit > nmp->nm_wcommitsize) {
  986                                 np->n_attrstamp = 0;
  987                                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  988                                 error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  989                                 if (error)
  990                                         return (error);
  991                                 wouldcommit = biosize;
  992                         }
  993                 }
  994 
  995                 NFSINCRGLOBAL(newnfsstats.biocache_writes);
  996                 lbn = uio->uio_offset / biosize;
  997                 on = uio->uio_offset - (lbn * biosize);
  998                 n = MIN((unsigned)(biosize - on), uio->uio_resid);
  999 again:
 1000                 /*
 1001                  * Handle direct append and file extension cases, calculate
 1002                  * unaligned buffer size.
 1003                  */
 1004                 mtx_lock(&np->n_mtx);
 1005                 if ((np->n_flag & NHASBEENLOCKED) == 0 &&
 1006                     (nmp->nm_flag & NFSMNT_NONCONTIGWR) != 0)
 1007                         noncontig_write = 1;
 1008                 else
 1009                         noncontig_write = 0;
 1010                 if ((uio->uio_offset == np->n_size ||
 1011                     (noncontig_write != 0 &&
 1012                     lbn == (np->n_size / biosize) &&
 1013                     uio->uio_offset + n > np->n_size)) && n) {
 1014                         mtx_unlock(&np->n_mtx);
 1015                         /*
 1016                          * Get the buffer (in its pre-append state to maintain
 1017                          * B_CACHE if it was previously set).  Resize the
 1018                          * nfsnode after we have locked the buffer to prevent
 1019                          * readers from reading garbage.
 1020                          */
 1021                         obcount = np->n_size - (lbn * biosize);
 1022                         bp = nfs_getcacheblk(vp, lbn, obcount, td);
 1023 
 1024                         if (bp != NULL) {
 1025                                 long save;
 1026 
 1027                                 mtx_lock(&np->n_mtx);
 1028                                 np->n_size = uio->uio_offset + n;
 1029                                 np->n_flag |= NMODIFIED;
 1030                                 vnode_pager_setsize(vp, np->n_size);
 1031                                 mtx_unlock(&np->n_mtx);
 1032 
 1033                                 save = bp->b_flags & B_CACHE;
 1034                                 bcount = on + n;
 1035                                 allocbuf(bp, bcount);
 1036                                 bp->b_flags |= save;
 1037                                 if (noncontig_write != 0 && on > obcount)
 1038                                         vfs_bio_bzero_buf(bp, obcount, on -
 1039                                             obcount);
 1040                         }
 1041                 } else {
 1042                         /*
 1043                          * Obtain the locked cache block first, and then
 1044                          * adjust the file's size as appropriate.
 1045                          */
 1046                         bcount = on + n;
 1047                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1048                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1049                                         bcount = biosize;
 1050                                 else
 1051                                         bcount = np->n_size - (off_t)lbn * biosize;
 1052                         }
 1053                         mtx_unlock(&np->n_mtx);
 1054                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1055                         mtx_lock(&np->n_mtx);
 1056                         if (uio->uio_offset + n > np->n_size) {
 1057                                 np->n_size = uio->uio_offset + n;
 1058                                 np->n_flag |= NMODIFIED;
 1059                                 vnode_pager_setsize(vp, np->n_size);
 1060                         }
 1061                         mtx_unlock(&np->n_mtx);
 1062                 }
 1063 
 1064                 if (!bp) {
 1065                         error = newnfs_sigintr(nmp, td);
 1066                         if (!error)
 1067                                 error = EINTR;
 1068                         break;
 1069                 }
 1070 
 1071                 /*
 1072                  * Issue a READ if B_CACHE is not set.  In special-append
 1073                  * mode, B_CACHE is based on the buffer prior to the write
 1074                  * op and is typically set, avoiding the read.  If a read
 1075                  * is required in special append mode, the server will
 1076                  * probably send us a short-read since we extended the file
 1077                  * on our end, resulting in b_resid == 0 and, thusly,
 1078                  * B_CACHE getting set.
 1079                  *
 1080                  * We can also avoid issuing the read if the write covers
 1081                  * the entire buffer.  We have to make sure the buffer state
 1082                  * is reasonable in this case since we will not be initiating
 1083                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1084                  * more information.
 1085                  *
 1086                  * B_CACHE may also be set due to the buffer being cached
 1087                  * normally.
 1088                  */
 1089 
 1090                 bp_cached = 1;
 1091                 if (on == 0 && n == bcount) {
 1092                         if ((bp->b_flags & B_CACHE) == 0)
 1093                                 bp_cached = 0;
 1094                         bp->b_flags |= B_CACHE;
 1095                         bp->b_flags &= ~B_INVAL;
 1096                         bp->b_ioflags &= ~BIO_ERROR;
 1097                 }
 1098 
 1099                 if ((bp->b_flags & B_CACHE) == 0) {
 1100                         bp->b_iocmd = BIO_READ;
 1101                         vfs_busy_pages(bp, 0);
 1102                         error = ncl_doio(vp, bp, cred, td, 0);
 1103                         if (error) {
 1104                                 brelse(bp);
 1105                                 break;
 1106                         }
 1107                 }
 1108                 if (bp->b_wcred == NOCRED)
 1109                         bp->b_wcred = crhold(cred);
 1110                 mtx_lock(&np->n_mtx);
 1111                 np->n_flag |= NMODIFIED;
 1112                 mtx_unlock(&np->n_mtx);
 1113 
 1114                 /*
 1115                  * If dirtyend exceeds file size, chop it down.  This should
 1116                  * not normally occur but there is an append race where it
 1117                  * might occur XXX, so we log it.
 1118                  *
 1119                  * If the chopping creates a reverse-indexed or degenerate
 1120                  * situation with dirtyoff/end, we 0 both of them.
 1121                  */
 1122 
 1123                 if (bp->b_dirtyend > bcount) {
 1124                         printf("NFS append race @%lx:%d\n",
 1125                             (long)bp->b_blkno * DEV_BSIZE,
 1126                             bp->b_dirtyend - bcount);
 1127                         bp->b_dirtyend = bcount;
 1128                 }
 1129 
 1130                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1131                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1132 
 1133                 /*
 1134                  * If the new write will leave a contiguous dirty
 1135                  * area, just update the b_dirtyoff and b_dirtyend,
 1136                  * otherwise force a write rpc of the old dirty area.
 1137                  *
 1138                  * If there has been a file lock applied to this file
 1139                  * or vfs.nfs.old_noncontig_writing is set, do the following:
 1140                  * While it is possible to merge discontiguous writes due to
 1141                  * our having a B_CACHE buffer ( and thus valid read data
 1142                  * for the hole), we don't because it could lead to
 1143                  * significant cache coherency problems with multiple clients,
 1144                  * especially if locking is implemented later on.
 1145                  *
 1146                  * If vfs.nfs.old_noncontig_writing is not set and there has
 1147                  * not been file locking done on this file:
 1148                  * Relax coherency a bit for the sake of performance and
 1149                  * expand the current dirty region to contain the new
 1150                  * write even if it means we mark some non-dirty data as
 1151                  * dirty.
 1152                  */
 1153 
 1154                 if (noncontig_write == 0 && bp->b_dirtyend > 0 &&
 1155                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1156                         if (bwrite(bp) == EINTR) {
 1157                                 error = EINTR;
 1158                                 break;
 1159                         }
 1160                         goto again;
 1161                 }
 1162 
 1163                 local_resid = uio->uio_resid;
 1164                 error = vn_io_fault_uiomove((char *)bp->b_data + on, n, uio);
 1165 
 1166                 if (error != 0 && !bp_cached) {
 1167                         /*
 1168                          * This block has no other content then what
 1169                          * possibly was written by the faulty uiomove.
 1170                          * Release it, forgetting the data pages, to
 1171                          * prevent the leak of uninitialized data to
 1172                          * usermode.
 1173                          */
 1174                         bp->b_ioflags |= BIO_ERROR;
 1175                         brelse(bp);
 1176                         uio->uio_offset -= local_resid - uio->uio_resid;
 1177                         uio->uio_resid = local_resid;
 1178                         break;
 1179                 }
 1180 
 1181                 /*
 1182                  * Since this block is being modified, it must be written
 1183                  * again and not just committed.  Since write clustering does
 1184                  * not work for the stage 1 data write, only the stage 2
 1185                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1186                  */
 1187                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1188 
 1189                 /*
 1190                  * Get the partial update on the progress made from
 1191                  * uiomove, if an error occurred.
 1192                  */
 1193                 if (error != 0)
 1194                         n = local_resid - uio->uio_resid;
 1195 
 1196                 /*
 1197                  * Only update dirtyoff/dirtyend if not a degenerate
 1198                  * condition.
 1199                  */
 1200                 if (n > 0) {
 1201                         if (bp->b_dirtyend > 0) {
 1202                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1203                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1204                         } else {
 1205                                 bp->b_dirtyoff = on;
 1206                                 bp->b_dirtyend = on + n;
 1207                         }
 1208                         vfs_bio_set_valid(bp, on, n);
 1209                 }
 1210 
 1211                 /*
 1212                  * If IO_SYNC do bwrite().
 1213                  *
 1214                  * IO_INVAL appears to be unused.  The idea appears to be
 1215                  * to turn off caching in this case.  Very odd.  XXX
 1216                  */
 1217                 if ((ioflag & IO_SYNC)) {
 1218                         if (ioflag & IO_INVAL)
 1219                                 bp->b_flags |= B_NOCACHE;
 1220                         error1 = bwrite(bp);
 1221                         if (error1 != 0) {
 1222                                 if (error == 0)
 1223                                         error = error1;
 1224                                 break;
 1225                         }
 1226                 } else if ((n + on) == biosize) {
 1227                         bp->b_flags |= B_ASYNC;
 1228                         (void) ncl_writebp(bp, 0, NULL);
 1229                 } else {
 1230                         bdwrite(bp);
 1231                 }
 1232 
 1233                 if (error != 0)
 1234                         break;
 1235         } while (uio->uio_resid > 0 && n > 0);
 1236 
 1237         if (error != 0) {
 1238                 if (ioflag & IO_UNIT) {
 1239                         VATTR_NULL(&vattr);
 1240                         vattr.va_size = orig_size;
 1241                         /* IO_SYNC is handled implicitely */
 1242                         (void)VOP_SETATTR(vp, &vattr, cred);
 1243                         uio->uio_offset -= orig_resid - uio->uio_resid;
 1244                         uio->uio_resid = orig_resid;
 1245                 }
 1246         }
 1247 
 1248         return (error);
 1249 }
 1250 
 1251 /*
 1252  * Get an nfs cache block.
 1253  *
 1254  * Allocate a new one if the block isn't currently in the cache
 1255  * and return the block marked busy. If the calling process is
 1256  * interrupted by a signal for an interruptible mount point, return
 1257  * NULL.
 1258  *
 1259  * The caller must carefully deal with the possible B_INVAL state of
 1260  * the buffer.  ncl_doio() clears B_INVAL (and ncl_asyncio() clears it
 1261  * indirectly), so synchronous reads can be issued without worrying about
 1262  * the B_INVAL state.  We have to be a little more careful when dealing
 1263  * with writes (see comments in nfs_write()) when extending a file past
 1264  * its EOF.
 1265  */
 1266 static struct buf *
 1267 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1268 {
 1269         struct buf *bp;
 1270         struct mount *mp;
 1271         struct nfsmount *nmp;
 1272 
 1273         mp = vp->v_mount;
 1274         nmp = VFSTONFS(mp);
 1275 
 1276         if (nmp->nm_flag & NFSMNT_INT) {
 1277                 sigset_t oldset;
 1278 
 1279                 newnfs_set_sigmask(td, &oldset);
 1280                 bp = getblk(vp, bn, size, PCATCH, 0, 0);
 1281                 newnfs_restore_sigmask(td, &oldset);
 1282                 while (bp == NULL) {
 1283                         if (newnfs_sigintr(nmp, td))
 1284                                 return (NULL);
 1285                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1286                 }
 1287         } else {
 1288                 bp = getblk(vp, bn, size, 0, 0, 0);
 1289         }
 1290 
 1291         if (vp->v_type == VREG)
 1292                 bp->b_blkno = bn * (vp->v_bufobj.bo_bsize / DEV_BSIZE);
 1293         return (bp);
 1294 }
 1295 
 1296 /*
 1297  * Flush and invalidate all dirty buffers. If another process is already
 1298  * doing the flush, just wait for completion.
 1299  */
 1300 int
 1301 ncl_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1302 {
 1303         struct nfsnode *np = VTONFS(vp);
 1304         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1305         int error = 0, slpflag, slptimeo;
 1306         int old_lock = 0;
 1307 
 1308         ASSERT_VOP_LOCKED(vp, "ncl_vinvalbuf");
 1309 
 1310         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1311                 intrflg = 0;
 1312         if ((nmp->nm_mountp->mnt_kern_flag & MNTK_UNMOUNTF))
 1313                 intrflg = 1;
 1314         if (intrflg) {
 1315                 slpflag = PCATCH;
 1316                 slptimeo = 2 * hz;
 1317         } else {
 1318                 slpflag = 0;
 1319                 slptimeo = 0;
 1320         }
 1321 
 1322         old_lock = ncl_upgrade_vnlock(vp);
 1323         if (vp->v_iflag & VI_DOOMED) {
 1324                 /*
 1325                  * Since vgonel() uses the generic vinvalbuf() to flush
 1326                  * dirty buffers and it does not call this function, it
 1327                  * is safe to just return OK when VI_DOOMED is set.
 1328                  */
 1329                 ncl_downgrade_vnlock(vp, old_lock);
 1330                 return (0);
 1331         }
 1332 
 1333         /*
 1334          * Now, flush as required.
 1335          */
 1336         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1337                 VM_OBJECT_WLOCK(vp->v_bufobj.bo_object);
 1338                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1339                 VM_OBJECT_WUNLOCK(vp->v_bufobj.bo_object);
 1340                 /*
 1341                  * If the page clean was interrupted, fail the invalidation.
 1342                  * Not doing so, we run the risk of losing dirty pages in the
 1343                  * vinvalbuf() call below.
 1344                  */
 1345                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1346                         goto out;
 1347         }
 1348 
 1349         error = vinvalbuf(vp, flags, slpflag, 0);
 1350         while (error) {
 1351                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1352                         goto out;
 1353                 error = vinvalbuf(vp, flags, 0, slptimeo);
 1354         }
 1355         if (NFSHASPNFS(nmp)) {
 1356                 nfscl_layoutcommit(vp, td);
 1357                 /*
 1358                  * Invalidate the attribute cache, since writes to a DS
 1359                  * won't update the size attribute.
 1360                  */
 1361                 mtx_lock(&np->n_mtx);
 1362                 np->n_attrstamp = 0;
 1363         } else
 1364                 mtx_lock(&np->n_mtx);
 1365         if (np->n_directio_asyncwr == 0)
 1366                 np->n_flag &= ~NMODIFIED;
 1367         mtx_unlock(&np->n_mtx);
 1368 out:
 1369         ncl_downgrade_vnlock(vp, old_lock);
 1370         return error;
 1371 }
 1372 
 1373 /*
 1374  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1375  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1376  * are all hung on a dead server.
 1377  *
 1378  * Note: ncl_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1379  * is eventually dequeued by the async daemon, ncl_doio() *will*.
 1380  */
 1381 int
 1382 ncl_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1383 {
 1384         int iod;
 1385         int gotiod;
 1386         int slpflag = 0;
 1387         int slptimeo = 0;
 1388         int error, error2;
 1389 
 1390         /*
 1391          * Commits are usually short and sweet so lets save some cpu and
 1392          * leave the async daemons for more important rpc's (such as reads
 1393          * and writes).
 1394          *
 1395          * Readdirplus RPCs do vget()s to acquire the vnodes for entries
 1396          * in the directory in order to update attributes. This can deadlock
 1397          * with another thread that is waiting for async I/O to be done by
 1398          * an nfsiod thread while holding a lock on one of these vnodes.
 1399          * To avoid this deadlock, don't allow the async nfsiod threads to
 1400          * perform Readdirplus RPCs.
 1401          */
 1402         mtx_lock(&ncl_iod_mutex);
 1403         if ((bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1404              (nmp->nm_bufqiods > ncl_numasync / 2)) ||
 1405             (bp->b_vp->v_type == VDIR && (nmp->nm_flag & NFSMNT_RDIRPLUS))) {
 1406                 mtx_unlock(&ncl_iod_mutex);
 1407                 return(EIO);
 1408         }
 1409 again:
 1410         if (nmp->nm_flag & NFSMNT_INT)
 1411                 slpflag = PCATCH;
 1412         gotiod = FALSE;
 1413 
 1414         /*
 1415          * Find a free iod to process this request.
 1416          */
 1417         for (iod = 0; iod < ncl_numasync; iod++)
 1418                 if (ncl_iodwant[iod] == NFSIOD_AVAILABLE) {
 1419                         gotiod = TRUE;
 1420                         break;
 1421                 }
 1422 
 1423         /*
 1424          * Try to create one if none are free.
 1425          */
 1426         if (!gotiod)
 1427                 ncl_nfsiodnew();
 1428         else {
 1429                 /*
 1430                  * Found one, so wake it up and tell it which
 1431                  * mount to process.
 1432                  */
 1433                 NFS_DPF(ASYNCIO, ("ncl_asyncio: waking iod %d for mount %p\n",
 1434                     iod, nmp));
 1435                 ncl_iodwant[iod] = NFSIOD_NOT_AVAILABLE;
 1436                 ncl_iodmount[iod] = nmp;
 1437                 nmp->nm_bufqiods++;
 1438                 wakeup(&ncl_iodwant[iod]);
 1439         }
 1440 
 1441         /*
 1442          * If none are free, we may already have an iod working on this mount
 1443          * point.  If so, it will process our request.
 1444          */
 1445         if (!gotiod) {
 1446                 if (nmp->nm_bufqiods > 0) {
 1447                         NFS_DPF(ASYNCIO,
 1448                                 ("ncl_asyncio: %d iods are already processing mount %p\n",
 1449                                  nmp->nm_bufqiods, nmp));
 1450                         gotiod = TRUE;
 1451                 }
 1452         }
 1453 
 1454         /*
 1455          * If we have an iod which can process the request, then queue
 1456          * the buffer.
 1457          */
 1458         if (gotiod) {
 1459                 /*
 1460                  * Ensure that the queue never grows too large.  We still want
 1461                  * to asynchronize so we block rather then return EIO.
 1462                  */
 1463                 while (nmp->nm_bufqlen >= 2*ncl_numasync) {
 1464                         NFS_DPF(ASYNCIO,
 1465                                 ("ncl_asyncio: waiting for mount %p queue to drain\n", nmp));
 1466                         nmp->nm_bufqwant = TRUE;
 1467                         error = newnfs_msleep(td, &nmp->nm_bufq,
 1468                             &ncl_iod_mutex, slpflag | PRIBIO, "nfsaio",
 1469                            slptimeo);
 1470                         if (error) {
 1471                                 error2 = newnfs_sigintr(nmp, td);
 1472                                 if (error2) {
 1473                                         mtx_unlock(&ncl_iod_mutex);
 1474                                         return (error2);
 1475                                 }
 1476                                 if (slpflag == PCATCH) {
 1477                                         slpflag = 0;
 1478                                         slptimeo = 2 * hz;
 1479                                 }
 1480                         }
 1481                         /*
 1482                          * We might have lost our iod while sleeping,
 1483                          * so check and loop if necessary.
 1484                          */
 1485                         goto again;
 1486                 }
 1487 
 1488                 /* We might have lost our nfsiod */
 1489                 if (nmp->nm_bufqiods == 0) {
 1490                         NFS_DPF(ASYNCIO,
 1491                                 ("ncl_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1492                         goto again;
 1493                 }
 1494 
 1495                 if (bp->b_iocmd == BIO_READ) {
 1496                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1497                                 bp->b_rcred = crhold(cred);
 1498                 } else {
 1499                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1500                                 bp->b_wcred = crhold(cred);
 1501                 }
 1502 
 1503                 if (bp->b_flags & B_REMFREE)
 1504                         bremfreef(bp);
 1505                 BUF_KERNPROC(bp);
 1506                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1507                 nmp->nm_bufqlen++;
 1508                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1509                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);
 1510                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1511                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1512                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1513                 }
 1514                 mtx_unlock(&ncl_iod_mutex);
 1515                 return (0);
 1516         }
 1517 
 1518         mtx_unlock(&ncl_iod_mutex);
 1519 
 1520         /*
 1521          * All the iods are busy on other mounts, so return EIO to
 1522          * force the caller to process the i/o synchronously.
 1523          */
 1524         NFS_DPF(ASYNCIO, ("ncl_asyncio: no iods available, i/o is synchronous\n"));
 1525         return (EIO);
 1526 }
 1527 
 1528 void
 1529 ncl_doio_directwrite(struct buf *bp)
 1530 {
 1531         int iomode, must_commit;
 1532         struct uio *uiop = (struct uio *)bp->b_caller1;
 1533         char *iov_base = uiop->uio_iov->iov_base;
 1534 
 1535         iomode = NFSWRITE_FILESYNC;
 1536         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1537         ncl_writerpc(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit, 0);
 1538         KASSERT((must_commit == 0), ("ncl_doio_directwrite: Did not commit write"));
 1539         free(iov_base, M_NFSDIRECTIO);
 1540         free(uiop->uio_iov, M_NFSDIRECTIO);
 1541         free(uiop, M_NFSDIRECTIO);
 1542         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1543                 struct nfsnode *np = VTONFS(bp->b_vp);
 1544                 mtx_lock(&np->n_mtx);
 1545                 if (NFSHASPNFS(VFSTONFS(vnode_mount(bp->b_vp)))) {
 1546                         /*
 1547                          * Invalidate the attribute cache, since writes to a DS
 1548                          * won't update the size attribute.
 1549                          */
 1550                         np->n_attrstamp = 0;
 1551                 }
 1552                 np->n_directio_asyncwr--;
 1553                 if (np->n_directio_asyncwr == 0) {
 1554                         np->n_flag &= ~NMODIFIED;
 1555                         if ((np->n_flag & NFSYNCWAIT)) {
 1556                                 np->n_flag &= ~NFSYNCWAIT;
 1557                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1558                         }
 1559                 }
 1560                 mtx_unlock(&np->n_mtx);
 1561         }
 1562         bp->b_vp = NULL;
 1563         relpbuf(bp, &ncl_pbuf_freecnt);
 1564 }
 1565 
 1566 /*
 1567  * Do an I/O operation to/from a cache block. This may be called
 1568  * synchronously or from an nfsiod.
 1569  */
 1570 int
 1571 ncl_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td,
 1572     int called_from_strategy)
 1573 {
 1574         struct uio *uiop;
 1575         struct nfsnode *np;
 1576         struct nfsmount *nmp;
 1577         int error = 0, iomode, must_commit = 0;
 1578         struct uio uio;
 1579         struct iovec io;
 1580         struct proc *p = td ? td->td_proc : NULL;
 1581         uint8_t iocmd;
 1582 
 1583         np = VTONFS(vp);
 1584         nmp = VFSTONFS(vp->v_mount);
 1585         uiop = &uio;
 1586         uiop->uio_iov = &io;
 1587         uiop->uio_iovcnt = 1;
 1588         uiop->uio_segflg = UIO_SYSSPACE;
 1589         uiop->uio_td = td;
 1590 
 1591         /*
 1592          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1593          * do this here so we do not have to do it in all the code that
 1594          * calls us.
 1595          */
 1596         bp->b_flags &= ~B_INVAL;
 1597         bp->b_ioflags &= ~BIO_ERROR;
 1598 
 1599         KASSERT(!(bp->b_flags & B_DONE), ("ncl_doio: bp %p already marked done", bp));
 1600         iocmd = bp->b_iocmd;
 1601         if (iocmd == BIO_READ) {
 1602             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1603             io.iov_base = bp->b_data;
 1604             uiop->uio_rw = UIO_READ;
 1605 
 1606             switch (vp->v_type) {
 1607             case VREG:
 1608                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1609                 NFSINCRGLOBAL(newnfsstats.read_bios);
 1610                 error = ncl_readrpc(vp, uiop, cr);
 1611 
 1612                 if (!error) {
 1613                     if (uiop->uio_resid) {
 1614                         /*
 1615                          * If we had a short read with no error, we must have
 1616                          * hit a file hole.  We should zero-fill the remainder.
 1617                          * This can also occur if the server hits the file EOF.
 1618                          *
 1619                          * Holes used to be able to occur due to pending
 1620                          * writes, but that is not possible any longer.
 1621                          */
 1622                         int nread = bp->b_bcount - uiop->uio_resid;
 1623                         ssize_t left = uiop->uio_resid;
 1624 
 1625                         if (left > 0)
 1626                                 bzero((char *)bp->b_data + nread, left);
 1627                         uiop->uio_resid = 0;
 1628                     }
 1629                 }
 1630                 /* ASSERT_VOP_LOCKED(vp, "ncl_doio"); */
 1631                 if (p && (vp->v_vflag & VV_TEXT)) {
 1632                         mtx_lock(&np->n_mtx);
 1633                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.na_mtime)) {
 1634                                 mtx_unlock(&np->n_mtx);
 1635                                 PROC_LOCK(p);
 1636                                 killproc(p, "text file modification");
 1637                                 PROC_UNLOCK(p);
 1638                         } else
 1639                                 mtx_unlock(&np->n_mtx);
 1640                 }
 1641                 break;
 1642             case VLNK:
 1643                 uiop->uio_offset = (off_t)0;
 1644                 NFSINCRGLOBAL(newnfsstats.readlink_bios);
 1645                 error = ncl_readlinkrpc(vp, uiop, cr);
 1646                 break;
 1647             case VDIR:
 1648                 NFSINCRGLOBAL(newnfsstats.readdir_bios);
 1649                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1650                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1651                         error = ncl_readdirplusrpc(vp, uiop, cr, td);
 1652                         if (error == NFSERR_NOTSUPP)
 1653                                 nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1654                 }
 1655                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1656                         error = ncl_readdirrpc(vp, uiop, cr, td);
 1657                 /*
 1658                  * end-of-directory sets B_INVAL but does not generate an
 1659                  * error.
 1660                  */
 1661                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1662                         bp->b_flags |= B_INVAL;
 1663                 break;
 1664             default:
 1665                 printf("ncl_doio:  type %x unexpected\n", vp->v_type);
 1666                 break;
 1667             }
 1668             if (error) {
 1669                 bp->b_ioflags |= BIO_ERROR;
 1670                 bp->b_error = error;
 1671             }
 1672         } else {
 1673             /*
 1674              * If we only need to commit, try to commit
 1675              */
 1676             if (bp->b_flags & B_NEEDCOMMIT) {
 1677                     int retv;
 1678                     off_t off;
 1679 
 1680                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1681                     retv = ncl_commit(vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1682                         bp->b_wcred, td);
 1683                     if (retv == 0) {
 1684                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1685                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1686                             bp->b_resid = 0;
 1687                             bufdone(bp);
 1688                             return (0);
 1689                     }
 1690                     if (retv == NFSERR_STALEWRITEVERF) {
 1691                             ncl_clearcommit(vp->v_mount);
 1692                     }
 1693             }
 1694 
 1695             /*
 1696              * Setup for actual write
 1697              */
 1698             mtx_lock(&np->n_mtx);
 1699             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1700                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1701             mtx_unlock(&np->n_mtx);
 1702 
 1703             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1704                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1705                     - bp->b_dirtyoff;
 1706                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1707                     + bp->b_dirtyoff;
 1708                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1709                 uiop->uio_rw = UIO_WRITE;
 1710                 NFSINCRGLOBAL(newnfsstats.write_bios);
 1711 
 1712                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1713                     iomode = NFSWRITE_UNSTABLE;
 1714                 else
 1715                     iomode = NFSWRITE_FILESYNC;
 1716 
 1717                 error = ncl_writerpc(vp, uiop, cr, &iomode, &must_commit,
 1718                     called_from_strategy);
 1719 
 1720                 /*
 1721                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1722                  * to cluster the buffers needing commit.  This will allow
 1723                  * the system to submit a single commit rpc for the whole
 1724                  * cluster.  We can do this even if the buffer is not 100%
 1725                  * dirty (relative to the NFS blocksize), so we optimize the
 1726                  * append-to-file-case.
 1727                  *
 1728                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1729                  * cleared because write clustering only works for commit
 1730                  * rpc's, not for the data portion of the write).
 1731                  */
 1732 
 1733                 if (!error && iomode == NFSWRITE_UNSTABLE) {
 1734                     bp->b_flags |= B_NEEDCOMMIT;
 1735                     if (bp->b_dirtyoff == 0
 1736                         && bp->b_dirtyend == bp->b_bcount)
 1737                         bp->b_flags |= B_CLUSTEROK;
 1738                 } else {
 1739                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1740                 }
 1741 
 1742                 /*
 1743                  * For an interrupted write, the buffer is still valid
 1744                  * and the write hasn't been pushed to the server yet,
 1745                  * so we can't set BIO_ERROR and report the interruption
 1746                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1747                  * is not relevant, so the rpc attempt is essentially
 1748                  * a noop.  For the case of a V3 write rpc not being
 1749                  * committed to stable storage, the block is still
 1750                  * dirty and requires either a commit rpc or another
 1751                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1752                  * the block is reused. This is indicated by setting
 1753                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1754                  *
 1755                  * EIO is returned by ncl_writerpc() to indicate a recoverable
 1756                  * write error and is handled as above, except that
 1757                  * B_EINTR isn't set. One cause of this is a stale stateid
 1758                  * error for the RPC that indicates recovery is required,
 1759                  * when called with called_from_strategy != 0.
 1760                  *
 1761                  * If the buffer is marked B_PAGING, it does not reside on
 1762                  * the vp's paging queues so we cannot call bdirty().  The
 1763                  * bp in this case is not an NFS cache block so we should
 1764                  * be safe. XXX
 1765                  *
 1766                  * The logic below breaks up errors into recoverable and
 1767                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1768                  * and keep the buffer around for potential write retries.
 1769                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1770                  * and save the error in the nfsnode. This is less than ideal
 1771                  * but necessary. Keeping such buffers around could potentially
 1772                  * cause buffer exhaustion eventually (they can never be written
 1773                  * out, so will get constantly be re-dirtied). It also causes
 1774                  * all sorts of vfs panics. For non-recoverable write errors,
 1775                  * also invalidate the attrcache, so we'll be forced to go over
 1776                  * the wire for this object, returning an error to user on next
 1777                  * call (most of the time).
 1778                  */
 1779                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1780                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1781                         int s;
 1782 
 1783                         s = splbio();
 1784                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1785                         if ((bp->b_flags & B_PAGING) == 0) {
 1786                             bdirty(bp);
 1787                             bp->b_flags &= ~B_DONE;
 1788                         }
 1789                         if ((error == EINTR || error == ETIMEDOUT) &&
 1790                             (bp->b_flags & B_ASYNC) == 0)
 1791                             bp->b_flags |= B_EINTR;
 1792                         splx(s);
 1793                 } else {
 1794                     if (error) {
 1795                         bp->b_ioflags |= BIO_ERROR;
 1796                         bp->b_flags |= B_INVAL;
 1797                         bp->b_error = np->n_error = error;
 1798                         mtx_lock(&np->n_mtx);
 1799                         np->n_flag |= NWRITEERR;
 1800                         np->n_attrstamp = 0;
 1801                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 1802                         mtx_unlock(&np->n_mtx);
 1803                     }
 1804                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1805                 }
 1806             } else {
 1807                 bp->b_resid = 0;
 1808                 bufdone(bp);
 1809                 return (0);
 1810             }
 1811         }
 1812         bp->b_resid = uiop->uio_resid;
 1813         if (must_commit)
 1814             ncl_clearcommit(vp->v_mount);
 1815         bufdone(bp);
 1816         return (error);
 1817 }
 1818 
 1819 /*
 1820  * Used to aid in handling ftruncate() operations on the NFS client side.
 1821  * Truncation creates a number of special problems for NFS.  We have to
 1822  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1823  * we have to properly handle VM pages or (potentially dirty) buffers
 1824  * that straddle the truncation point.
 1825  */
 1826 
 1827 int
 1828 ncl_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1829 {
 1830         struct nfsnode *np = VTONFS(vp);
 1831         u_quad_t tsize;
 1832         int biosize = vp->v_bufobj.bo_bsize;
 1833         int error = 0;
 1834 
 1835         mtx_lock(&np->n_mtx);
 1836         tsize = np->n_size;
 1837         np->n_size = nsize;
 1838         mtx_unlock(&np->n_mtx);
 1839 
 1840         if (nsize < tsize) {
 1841                 struct buf *bp;
 1842                 daddr_t lbn;
 1843                 int bufsize;
 1844 
 1845                 /*
 1846                  * vtruncbuf() doesn't get the buffer overlapping the
 1847                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1848                  * buffer that now needs to be truncated.
 1849                  */
 1850                 error = vtruncbuf(vp, cred, nsize, biosize);
 1851                 lbn = nsize / biosize;
 1852                 bufsize = nsize - (lbn * biosize);
 1853                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1854                 if (!bp)
 1855                         return EINTR;
 1856                 if (bp->b_dirtyoff > bp->b_bcount)
 1857                         bp->b_dirtyoff = bp->b_bcount;
 1858                 if (bp->b_dirtyend > bp->b_bcount)
 1859                         bp->b_dirtyend = bp->b_bcount;
 1860                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1861                 brelse(bp);
 1862         } else {
 1863                 vnode_pager_setsize(vp, nsize);
 1864         }
 1865         return(error);
 1866 }
 1867 

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