The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/nfsclient/nfs_bio.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/8.0/sys/nfsclient/nfs_bio.c 195703 2009-07-14 22:54:29Z kib $");
   37 
   38 #include "opt_kdtrace.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/bio.h>
   43 #include <sys/buf.h>
   44 #include <sys/kernel.h>
   45 #include <sys/mbuf.h>
   46 #include <sys/mount.h>
   47 #include <sys/proc.h>
   48 #include <sys/resourcevar.h>
   49 #include <sys/signalvar.h>
   50 #include <sys/vmmeter.h>
   51 #include <sys/vnode.h>
   52 
   53 #include <vm/vm.h>
   54 #include <vm/vm_extern.h>
   55 #include <vm/vm_page.h>
   56 #include <vm/vm_object.h>
   57 #include <vm/vm_pager.h>
   58 #include <vm/vnode_pager.h>
   59 
   60 #include <nfs/nfsproto.h>
   61 #include <nfsclient/nfs.h>
   62 #include <nfsclient/nfsmount.h>
   63 #include <nfsclient/nfsnode.h>
   64 #include <nfsclient/nfs_kdtrace.h>
   65 
   66 static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
   67                     struct thread *td);
   68 static int nfs_directio_write(struct vnode *vp, struct uio *uiop, 
   69                               struct ucred *cred, int ioflag);
   70 
   71 extern int nfs_directio_enable;
   72 extern int nfs_directio_allow_mmap;
   73 
   74 /*
   75  * Vnode op for VM getpages.
   76  */
   77 int
   78 nfs_getpages(struct vop_getpages_args *ap)
   79 {
   80         int i, error, nextoff, size, toff, count, npages;
   81         struct uio uio;
   82         struct iovec iov;
   83         vm_offset_t kva;
   84         struct buf *bp;
   85         struct vnode *vp;
   86         struct thread *td;
   87         struct ucred *cred;
   88         struct nfsmount *nmp;
   89         vm_object_t object;
   90         vm_page_t *pages;
   91         struct nfsnode *np;
   92 
   93         vp = ap->a_vp;
   94         np = VTONFS(vp);
   95         td = curthread;                         /* XXX */
   96         cred = curthread->td_ucred;             /* XXX */
   97         nmp = VFSTONFS(vp->v_mount);
   98         pages = ap->a_m;
   99         count = ap->a_count;
  100 
  101         if ((object = vp->v_object) == NULL) {
  102                 nfs_printf("nfs_getpages: called with non-merged cache vnode??\n");
  103                 return (VM_PAGER_ERROR);
  104         }
  105 
  106         if (nfs_directio_enable && !nfs_directio_allow_mmap) {
  107                 mtx_lock(&np->n_mtx);
  108                 if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  109                         mtx_unlock(&np->n_mtx);
  110                         nfs_printf("nfs_getpages: called on non-cacheable vnode??\n");
  111                         return (VM_PAGER_ERROR);
  112                 } else
  113                         mtx_unlock(&np->n_mtx);
  114         }
  115 
  116         mtx_lock(&nmp->nm_mtx);
  117         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  118             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {  
  119                 mtx_unlock(&nmp->nm_mtx);
  120                 /* We'll never get here for v4, because we always have fsinfo */
  121                 (void)nfs_fsinfo(nmp, vp, cred, td);
  122         } else
  123                 mtx_unlock(&nmp->nm_mtx);
  124 
  125         npages = btoc(count);
  126 
  127         /*
  128          * If the requested page is partially valid, just return it and
  129          * allow the pager to zero-out the blanks.  Partially valid pages
  130          * can only occur at the file EOF.
  131          */
  132         VM_OBJECT_LOCK(object);
  133         if (pages[ap->a_reqpage]->valid != 0) {
  134                 vm_page_lock_queues();
  135                 for (i = 0; i < npages; ++i) {
  136                         if (i != ap->a_reqpage)
  137                                 vm_page_free(pages[i]);
  138                 }
  139                 vm_page_unlock_queues();
  140                 VM_OBJECT_UNLOCK(object);
  141                 return (0);
  142         }
  143         VM_OBJECT_UNLOCK(object);
  144 
  145         /*
  146          * We use only the kva address for the buffer, but this is extremely
  147          * convienient and fast.
  148          */
  149         bp = getpbuf(&nfs_pbuf_freecnt);
  150 
  151         kva = (vm_offset_t) bp->b_data;
  152         pmap_qenter(kva, pages, npages);
  153         PCPU_INC(cnt.v_vnodein);
  154         PCPU_ADD(cnt.v_vnodepgsin, npages);
  155 
  156         iov.iov_base = (caddr_t) kva;
  157         iov.iov_len = count;
  158         uio.uio_iov = &iov;
  159         uio.uio_iovcnt = 1;
  160         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  161         uio.uio_resid = count;
  162         uio.uio_segflg = UIO_SYSSPACE;
  163         uio.uio_rw = UIO_READ;
  164         uio.uio_td = td;
  165 
  166         error = (nmp->nm_rpcops->nr_readrpc)(vp, &uio, cred);
  167         pmap_qremove(kva, npages);
  168 
  169         relpbuf(bp, &nfs_pbuf_freecnt);
  170 
  171         if (error && (uio.uio_resid == count)) {
  172                 nfs_printf("nfs_getpages: error %d\n", error);
  173                 VM_OBJECT_LOCK(object);
  174                 vm_page_lock_queues();
  175                 for (i = 0; i < npages; ++i) {
  176                         if (i != ap->a_reqpage)
  177                                 vm_page_free(pages[i]);
  178                 }
  179                 vm_page_unlock_queues();
  180                 VM_OBJECT_UNLOCK(object);
  181                 return (VM_PAGER_ERROR);
  182         }
  183 
  184         /*
  185          * Calculate the number of bytes read and validate only that number
  186          * of bytes.  Note that due to pending writes, size may be 0.  This
  187          * does not mean that the remaining data is invalid!
  188          */
  189 
  190         size = count - uio.uio_resid;
  191         VM_OBJECT_LOCK(object);
  192         vm_page_lock_queues();
  193         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  194                 vm_page_t m;
  195                 nextoff = toff + PAGE_SIZE;
  196                 m = pages[i];
  197 
  198                 if (nextoff <= size) {
  199                         /*
  200                          * Read operation filled an entire page
  201                          */
  202                         m->valid = VM_PAGE_BITS_ALL;
  203                         KASSERT(m->dirty == 0,
  204                             ("nfs_getpages: page %p is dirty", m));
  205                 } else if (size > toff) {
  206                         /*
  207                          * Read operation filled a partial page.
  208                          */
  209                         m->valid = 0;
  210                         vm_page_set_valid(m, 0, size - toff);
  211                         KASSERT(m->dirty == 0,
  212                             ("nfs_getpages: page %p is dirty", m));
  213                 } else {
  214                         /*
  215                          * Read operation was short.  If no error occured
  216                          * we may have hit a zero-fill section.   We simply
  217                          * leave valid set to 0.
  218                          */
  219                         ;
  220                 }
  221                 if (i != ap->a_reqpage) {
  222                         /*
  223                          * Whether or not to leave the page activated is up in
  224                          * the air, but we should put the page on a page queue
  225                          * somewhere (it already is in the object).  Result:
  226                          * It appears that emperical results show that
  227                          * deactivating pages is best.
  228                          */
  229 
  230                         /*
  231                          * Just in case someone was asking for this page we
  232                          * now tell them that it is ok to use.
  233                          */
  234                         if (!error) {
  235                                 if (m->oflags & VPO_WANTED)
  236                                         vm_page_activate(m);
  237                                 else
  238                                         vm_page_deactivate(m);
  239                                 vm_page_wakeup(m);
  240                         } else {
  241                                 vm_page_free(m);
  242                         }
  243                 }
  244         }
  245         vm_page_unlock_queues();
  246         VM_OBJECT_UNLOCK(object);
  247         return (0);
  248 }
  249 
  250 /*
  251  * Vnode op for VM putpages.
  252  */
  253 int
  254 nfs_putpages(struct vop_putpages_args *ap)
  255 {
  256         struct uio uio;
  257         struct iovec iov;
  258         vm_offset_t kva;
  259         struct buf *bp;
  260         int iomode, must_commit, i, error, npages, count;
  261         off_t offset;
  262         int *rtvals;
  263         struct vnode *vp;
  264         struct thread *td;
  265         struct ucred *cred;
  266         struct nfsmount *nmp;
  267         struct nfsnode *np;
  268         vm_page_t *pages;
  269 
  270         vp = ap->a_vp;
  271         np = VTONFS(vp);
  272         td = curthread;                         /* XXX */
  273         cred = curthread->td_ucred;             /* XXX */
  274         nmp = VFSTONFS(vp->v_mount);
  275         pages = ap->a_m;
  276         count = ap->a_count;
  277         rtvals = ap->a_rtvals;
  278         npages = btoc(count);
  279         offset = IDX_TO_OFF(pages[0]->pindex);
  280         
  281         mtx_lock(&nmp->nm_mtx);
  282         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  283             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  284                 mtx_unlock(&nmp->nm_mtx);
  285                 (void)nfs_fsinfo(nmp, vp, cred, td);
  286         } else
  287                 mtx_unlock(&nmp->nm_mtx);
  288 
  289         mtx_lock(&np->n_mtx);
  290         if (nfs_directio_enable && !nfs_directio_allow_mmap && 
  291             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  292                 mtx_unlock(&np->n_mtx);         
  293                 nfs_printf("nfs_putpages: called on noncache-able vnode??\n");
  294                 mtx_lock(&np->n_mtx);
  295         }
  296 
  297         for (i = 0; i < npages; i++)
  298                 rtvals[i] = VM_PAGER_AGAIN;
  299 
  300         /*
  301          * When putting pages, do not extend file past EOF.
  302          */
  303         if (offset + count > np->n_size) {
  304                 count = np->n_size - offset;
  305                 if (count < 0)
  306                         count = 0;
  307         }
  308         mtx_unlock(&np->n_mtx);
  309 
  310         /*
  311          * We use only the kva address for the buffer, but this is extremely
  312          * convienient and fast.
  313          */
  314         bp = getpbuf(&nfs_pbuf_freecnt);
  315 
  316         kva = (vm_offset_t) bp->b_data;
  317         pmap_qenter(kva, pages, npages);
  318         PCPU_INC(cnt.v_vnodeout);
  319         PCPU_ADD(cnt.v_vnodepgsout, count);
  320 
  321         iov.iov_base = (caddr_t) kva;
  322         iov.iov_len = count;
  323         uio.uio_iov = &iov;
  324         uio.uio_iovcnt = 1;
  325         uio.uio_offset = offset;
  326         uio.uio_resid = count;
  327         uio.uio_segflg = UIO_SYSSPACE;
  328         uio.uio_rw = UIO_WRITE;
  329         uio.uio_td = td;
  330 
  331         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  332             iomode = NFSV3WRITE_UNSTABLE;
  333         else
  334             iomode = NFSV3WRITE_FILESYNC;
  335 
  336         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, &iomode, &must_commit);
  337 
  338         pmap_qremove(kva, npages);
  339         relpbuf(bp, &nfs_pbuf_freecnt);
  340 
  341         if (!error) {
  342                 int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
  343                 for (i = 0; i < nwritten; i++) {
  344                         rtvals[i] = VM_PAGER_OK;
  345                         vm_page_undirty(pages[i]);
  346                 }
  347                 if (must_commit) {
  348                         nfs_clearcommit(vp->v_mount);
  349                 }
  350         }
  351         return rtvals[0];
  352 }
  353 
  354 /*
  355  * For nfs, cache consistency can only be maintained approximately.
  356  * Although RFC1094 does not specify the criteria, the following is
  357  * believed to be compatible with the reference port.
  358  * For nfs:
  359  * If the file's modify time on the server has changed since the
  360  * last read rpc or you have written to the file,
  361  * you may have lost data cache consistency with the
  362  * server, so flush all of the file's data out of the cache.
  363  * Then force a getattr rpc to ensure that you have up to date
  364  * attributes.
  365  * NB: This implies that cache data can be read when up to
  366  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  367  * attributes this could be forced by setting n_attrstamp to 0 before
  368  * the VOP_GETATTR() call.
  369  */
  370 static inline int
  371 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  372 {
  373         int error = 0;
  374         struct vattr vattr;
  375         struct nfsnode *np = VTONFS(vp);
  376         int old_lock;
  377         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  378         
  379         /*
  380          * Grab the exclusive lock before checking whether the cache is
  381          * consistent.
  382          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  383          * But for now, this suffices.
  384          */
  385         old_lock = nfs_upgrade_vnlock(vp);
  386         if (vp->v_iflag & VI_DOOMED) {
  387                 nfs_downgrade_vnlock(vp, old_lock);
  388                 return (EBADF);
  389         }
  390                 
  391         mtx_lock(&np->n_mtx);
  392         if (np->n_flag & NMODIFIED) {
  393                 mtx_unlock(&np->n_mtx);
  394                 if (vp->v_type != VREG) {
  395                         if (vp->v_type != VDIR)
  396                                 panic("nfs: bioread, not dir");
  397                         (nmp->nm_rpcops->nr_invaldir)(vp);
  398                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  399                         if (error)
  400                                 goto out;
  401                 }
  402                 np->n_attrstamp = 0;
  403                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  404                 error = VOP_GETATTR(vp, &vattr, cred);
  405                 if (error)
  406                         goto out;
  407                 mtx_lock(&np->n_mtx);
  408                 np->n_mtime = vattr.va_mtime;
  409                 mtx_unlock(&np->n_mtx);
  410         } else {
  411                 mtx_unlock(&np->n_mtx);
  412                 error = VOP_GETATTR(vp, &vattr, cred);
  413                 if (error)
  414                         return (error);
  415                 mtx_lock(&np->n_mtx);
  416                 if ((np->n_flag & NSIZECHANGED)
  417                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  418                         mtx_unlock(&np->n_mtx);
  419                         if (vp->v_type == VDIR)
  420                                 (nmp->nm_rpcops->nr_invaldir)(vp);
  421                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  422                         if (error)
  423                                 goto out;
  424                         mtx_lock(&np->n_mtx);
  425                         np->n_mtime = vattr.va_mtime;
  426                         np->n_flag &= ~NSIZECHANGED;
  427                 }
  428                 mtx_unlock(&np->n_mtx);
  429         }
  430 out:    
  431         nfs_downgrade_vnlock(vp, old_lock);
  432         return error;
  433 }
  434 
  435 /*
  436  * Vnode op for read using bio
  437  */
  438 int
  439 nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  440 {
  441         struct nfsnode *np = VTONFS(vp);
  442         int biosize, i;
  443         struct buf *bp, *rabp;
  444         struct thread *td;
  445         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  446         daddr_t lbn, rabn;
  447         int bcount;
  448         int seqcount;
  449         int nra, error = 0, n = 0, on = 0;
  450 
  451 #ifdef DIAGNOSTIC
  452         if (uio->uio_rw != UIO_READ)
  453                 panic("nfs_read mode");
  454 #endif
  455         if (uio->uio_resid == 0)
  456                 return (0);
  457         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  458                 return (EINVAL);
  459         td = uio->uio_td;
  460 
  461         mtx_lock(&nmp->nm_mtx);
  462         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  463             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  464                 mtx_unlock(&nmp->nm_mtx);
  465                 (void)nfs_fsinfo(nmp, vp, cred, td);
  466         } else
  467                 mtx_unlock(&nmp->nm_mtx);               
  468 
  469         if (vp->v_type != VDIR &&
  470             (uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  471                 return (EFBIG);
  472 
  473         if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  474                 /* No caching/ no readaheads. Just read data into the user buffer */
  475                 return nfs_readrpc(vp, uio, cred);
  476 
  477         biosize = vp->v_mount->mnt_stat.f_iosize;
  478         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  479         
  480         error = nfs_bioread_check_cons(vp, td, cred);
  481         if (error)
  482                 return error;
  483 
  484         do {
  485             u_quad_t nsize;
  486                         
  487             mtx_lock(&np->n_mtx);
  488             nsize = np->n_size;
  489             mtx_unlock(&np->n_mtx);                 
  490 
  491             switch (vp->v_type) {
  492             case VREG:
  493                 nfsstats.biocache_reads++;
  494                 lbn = uio->uio_offset / biosize;
  495                 on = uio->uio_offset & (biosize - 1);
  496 
  497                 /*
  498                  * Start the read ahead(s), as required.
  499                  */
  500                 if (nmp->nm_readahead > 0) {
  501                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  502                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  503                         rabn = lbn + 1 + nra;
  504                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  505                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  506                             if (!rabp) {
  507                                 error = nfs_sigintr(nmp, td);
  508                                 return (error ? error : EINTR);
  509                             }
  510                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  511                                 rabp->b_flags |= B_ASYNC;
  512                                 rabp->b_iocmd = BIO_READ;
  513                                 vfs_busy_pages(rabp, 0);
  514                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  515                                     rabp->b_flags |= B_INVAL;
  516                                     rabp->b_ioflags |= BIO_ERROR;
  517                                     vfs_unbusy_pages(rabp);
  518                                     brelse(rabp);
  519                                     break;
  520                                 }
  521                             } else {
  522                                 brelse(rabp);
  523                             }
  524                         }
  525                     }
  526                 }
  527 
  528                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  529                 bcount = biosize;
  530                 if ((off_t)lbn * biosize >= nsize) {
  531                         bcount = 0;
  532                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  533                         bcount = nsize - (off_t)lbn * biosize;
  534                 }
  535                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  536 
  537                 if (!bp) {
  538                         error = nfs_sigintr(nmp, td);
  539                         return (error ? error : EINTR);
  540                 }
  541 
  542                 /*
  543                  * If B_CACHE is not set, we must issue the read.  If this
  544                  * fails, we return an error.
  545                  */
  546 
  547                 if ((bp->b_flags & B_CACHE) == 0) {
  548                     bp->b_iocmd = BIO_READ;
  549                     vfs_busy_pages(bp, 0);
  550                     error = nfs_doio(vp, bp, cred, td);
  551                     if (error) {
  552                         brelse(bp);
  553                         return (error);
  554                     }
  555                 }
  556 
  557                 /*
  558                  * on is the offset into the current bp.  Figure out how many
  559                  * bytes we can copy out of the bp.  Note that bcount is
  560                  * NOT DEV_BSIZE aligned.
  561                  *
  562                  * Then figure out how many bytes we can copy into the uio.
  563                  */
  564 
  565                 n = 0;
  566                 if (on < bcount)
  567                         n = min((unsigned)(bcount - on), uio->uio_resid);
  568                 break;
  569             case VLNK:
  570                 nfsstats.biocache_readlinks++;
  571                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  572                 if (!bp) {
  573                         error = nfs_sigintr(nmp, td);
  574                         return (error ? error : EINTR);
  575                 }
  576                 if ((bp->b_flags & B_CACHE) == 0) {
  577                     bp->b_iocmd = BIO_READ;
  578                     vfs_busy_pages(bp, 0);
  579                     error = nfs_doio(vp, bp, cred, td);
  580                     if (error) {
  581                         bp->b_ioflags |= BIO_ERROR;
  582                         brelse(bp);
  583                         return (error);
  584                     }
  585                 }
  586                 n = min(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  587                 on = 0;
  588                 break;
  589             case VDIR:
  590                 nfsstats.biocache_readdirs++;
  591                 if (np->n_direofoffset
  592                     && uio->uio_offset >= np->n_direofoffset) {
  593                     return (0);
  594                 }
  595                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  596                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  597                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  598                 if (!bp) {
  599                     error = nfs_sigintr(nmp, td);
  600                     return (error ? error : EINTR);
  601                 }
  602                 if ((bp->b_flags & B_CACHE) == 0) {
  603                     bp->b_iocmd = BIO_READ;
  604                     vfs_busy_pages(bp, 0);
  605                     error = nfs_doio(vp, bp, cred, td);
  606                     if (error) {
  607                             brelse(bp);
  608                     }
  609                     while (error == NFSERR_BAD_COOKIE) {
  610                         (nmp->nm_rpcops->nr_invaldir)(vp);
  611                         error = nfs_vinvalbuf(vp, 0, td, 1);
  612                         /*
  613                          * Yuck! The directory has been modified on the
  614                          * server. The only way to get the block is by
  615                          * reading from the beginning to get all the
  616                          * offset cookies.
  617                          *
  618                          * Leave the last bp intact unless there is an error.
  619                          * Loop back up to the while if the error is another
  620                          * NFSERR_BAD_COOKIE (double yuch!).
  621                          */
  622                         for (i = 0; i <= lbn && !error; i++) {
  623                             if (np->n_direofoffset
  624                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  625                                     return (0);
  626                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  627                             if (!bp) {
  628                                 error = nfs_sigintr(nmp, td);
  629                                 return (error ? error : EINTR);
  630                             }
  631                             if ((bp->b_flags & B_CACHE) == 0) {
  632                                     bp->b_iocmd = BIO_READ;
  633                                     vfs_busy_pages(bp, 0);
  634                                     error = nfs_doio(vp, bp, cred, td);
  635                                     /*
  636                                      * no error + B_INVAL == directory EOF,
  637                                      * use the block.
  638                                      */
  639                                     if (error == 0 && (bp->b_flags & B_INVAL))
  640                                             break;
  641                             }
  642                             /*
  643                              * An error will throw away the block and the
  644                              * for loop will break out.  If no error and this
  645                              * is not the block we want, we throw away the
  646                              * block and go for the next one via the for loop.
  647                              */
  648                             if (error || i < lbn)
  649                                     brelse(bp);
  650                         }
  651                     }
  652                     /*
  653                      * The above while is repeated if we hit another cookie
  654                      * error.  If we hit an error and it wasn't a cookie error,
  655                      * we give up.
  656                      */
  657                     if (error)
  658                             return (error);
  659                 }
  660 
  661                 /*
  662                  * If not eof and read aheads are enabled, start one.
  663                  * (You need the current block first, so that you have the
  664                  *  directory offset cookie of the next block.)
  665                  */
  666                 if (nmp->nm_readahead > 0 &&
  667                     (bp->b_flags & B_INVAL) == 0 &&
  668                     (np->n_direofoffset == 0 ||
  669                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  670                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  671                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  672                         if (rabp) {
  673                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  674                                 rabp->b_flags |= B_ASYNC;
  675                                 rabp->b_iocmd = BIO_READ;
  676                                 vfs_busy_pages(rabp, 0);
  677                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  678                                     rabp->b_flags |= B_INVAL;
  679                                     rabp->b_ioflags |= BIO_ERROR;
  680                                     vfs_unbusy_pages(rabp);
  681                                     brelse(rabp);
  682                                 }
  683                             } else {
  684                                 brelse(rabp);
  685                             }
  686                         }
  687                 }
  688                 /*
  689                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  690                  * chopped for the EOF condition, we cannot tell how large
  691                  * NFS directories are going to be until we hit EOF.  So
  692                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  693                  * it just so happens that b_resid will effectively chop it
  694                  * to EOF.  *BUT* this information is lost if the buffer goes
  695                  * away and is reconstituted into a B_CACHE state ( due to
  696                  * being VMIO ) later.  So we keep track of the directory eof
  697                  * in np->n_direofoffset and chop it off as an extra step
  698                  * right here.
  699                  */
  700                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  701                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  702                         n = np->n_direofoffset - uio->uio_offset;
  703                 break;
  704             default:
  705                 nfs_printf(" nfs_bioread: type %x unexpected\n", vp->v_type);
  706                 bp = NULL;
  707                 break;
  708             };
  709 
  710             if (n > 0) {
  711                     error = uiomove(bp->b_data + on, (int)n, uio);
  712             }
  713             if (vp->v_type == VLNK)
  714                 n = 0;
  715             if (bp != NULL)
  716                 brelse(bp);
  717         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  718         return (error);
  719 }
  720 
  721 /*
  722  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  723  * break up iovecs accordingly (restricting them to wsize).
  724  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  725  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  726  * user buffer to a staging buffer and then a second copy from the staging
  727  * buffer to mbufs. This can be optimized by copying from the user buffer
  728  * directly into mbufs and passing the chain down, but that requires a 
  729  * fair amount of re-working of the relevant codepaths (and can be done
  730  * later).
  731  */
  732 static int
  733 nfs_directio_write(vp, uiop, cred, ioflag)
  734         struct vnode *vp;
  735         struct uio *uiop;
  736         struct ucred *cred;
  737         int ioflag;
  738 {
  739         int error;
  740         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  741         struct thread *td = uiop->uio_td;
  742         int size;
  743         int wsize;
  744         
  745         mtx_lock(&nmp->nm_mtx);
  746         wsize = nmp->nm_wsize;
  747         mtx_unlock(&nmp->nm_mtx);
  748         if (ioflag & IO_SYNC) {
  749                 int iomode, must_commit;
  750                 struct uio uio;
  751                 struct iovec iov;
  752 do_sync:
  753                 while (uiop->uio_resid > 0) {
  754                         size = min(uiop->uio_resid, wsize);
  755                         size = min(uiop->uio_iov->iov_len, size);
  756                         iov.iov_base = uiop->uio_iov->iov_base;
  757                         iov.iov_len = size;
  758                         uio.uio_iov = &iov;
  759                         uio.uio_iovcnt = 1;
  760                         uio.uio_offset = uiop->uio_offset;
  761                         uio.uio_resid = size;
  762                         uio.uio_segflg = UIO_USERSPACE;
  763                         uio.uio_rw = UIO_WRITE;
  764                         uio.uio_td = td;
  765                         iomode = NFSV3WRITE_FILESYNC;
  766                         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, 
  767                                                       &iomode, &must_commit);
  768                         KASSERT((must_commit == 0), 
  769                                 ("nfs_directio_write: Did not commit write"));
  770                         if (error)
  771                                 return (error);
  772                         uiop->uio_offset += size;
  773                         uiop->uio_resid -= size;
  774                         if (uiop->uio_iov->iov_len <= size) {
  775                                 uiop->uio_iovcnt--;
  776                                 uiop->uio_iov++;
  777                         } else {
  778                                 uiop->uio_iov->iov_base = 
  779                                         (char *)uiop->uio_iov->iov_base + size;
  780                                 uiop->uio_iov->iov_len -= size;
  781                         }
  782                 }
  783         } else {
  784                 struct uio *t_uio;
  785                 struct iovec *t_iov;
  786                 struct buf *bp;
  787                 
  788                 /*
  789                  * Break up the write into blocksize chunks and hand these
  790                  * over to nfsiod's for write back.
  791                  * Unfortunately, this incurs a copy of the data. Since 
  792                  * the user could modify the buffer before the write is 
  793                  * initiated.
  794                  * 
  795                  * The obvious optimization here is that one of the 2 copies
  796                  * in the async write path can be eliminated by copying the
  797                  * data here directly into mbufs and passing the mbuf chain
  798                  * down. But that will require a fair amount of re-working
  799                  * of the code and can be done if there's enough interest
  800                  * in NFS directio access.
  801                  */
  802                 while (uiop->uio_resid > 0) {
  803                         size = min(uiop->uio_resid, wsize);
  804                         size = min(uiop->uio_iov->iov_len, size);
  805                         bp = getpbuf(&nfs_pbuf_freecnt);
  806                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  807                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  808                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  809                         t_iov->iov_len = size;
  810                         t_uio->uio_iov = t_iov;
  811                         t_uio->uio_iovcnt = 1;
  812                         t_uio->uio_offset = uiop->uio_offset;
  813                         t_uio->uio_resid = size;
  814                         t_uio->uio_segflg = UIO_SYSSPACE;
  815                         t_uio->uio_rw = UIO_WRITE;
  816                         t_uio->uio_td = td;
  817                         bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
  818                         bp->b_flags |= B_DIRECT;
  819                         bp->b_iocmd = BIO_WRITE;
  820                         if (cred != NOCRED) {
  821                                 crhold(cred);
  822                                 bp->b_wcred = cred;
  823                         } else 
  824                                 bp->b_wcred = NOCRED;                   
  825                         bp->b_caller1 = (void *)t_uio;
  826                         bp->b_vp = vp;
  827                         error = nfs_asyncio(nmp, bp, NOCRED, td);
  828                         if (error) {
  829                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  830                                 free(t_iov, M_NFSDIRECTIO);
  831                                 free(t_uio, M_NFSDIRECTIO);
  832                                 bp->b_vp = NULL;
  833                                 relpbuf(bp, &nfs_pbuf_freecnt);
  834                                 if (error == EINTR)
  835                                         return (error);
  836                                 goto do_sync;
  837                         }
  838                         uiop->uio_offset += size;
  839                         uiop->uio_resid -= size;
  840                         if (uiop->uio_iov->iov_len <= size) {
  841                                 uiop->uio_iovcnt--;
  842                                 uiop->uio_iov++;
  843                         } else {
  844                                 uiop->uio_iov->iov_base = 
  845                                         (char *)uiop->uio_iov->iov_base + size;
  846                                 uiop->uio_iov->iov_len -= size;
  847                         }
  848                 }
  849         }
  850         return (0);
  851 }
  852 
  853 /*
  854  * Vnode op for write using bio
  855  */
  856 int
  857 nfs_write(struct vop_write_args *ap)
  858 {
  859         int biosize;
  860         struct uio *uio = ap->a_uio;
  861         struct thread *td = uio->uio_td;
  862         struct vnode *vp = ap->a_vp;
  863         struct nfsnode *np = VTONFS(vp);
  864         struct ucred *cred = ap->a_cred;
  865         int ioflag = ap->a_ioflag;
  866         struct buf *bp;
  867         struct vattr vattr;
  868         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  869         daddr_t lbn;
  870         int bcount;
  871         int n, on, error = 0;
  872         struct proc *p = td?td->td_proc:NULL;
  873 
  874 #ifdef DIAGNOSTIC
  875         if (uio->uio_rw != UIO_WRITE)
  876                 panic("nfs_write mode");
  877         if (uio->uio_segflg == UIO_USERSPACE && uio->uio_td != curthread)
  878                 panic("nfs_write proc");
  879 #endif
  880         if (vp->v_type != VREG)
  881                 return (EIO);
  882         mtx_lock(&np->n_mtx);
  883         if (np->n_flag & NWRITEERR) {
  884                 np->n_flag &= ~NWRITEERR;
  885                 mtx_unlock(&np->n_mtx);
  886                 return (np->n_error);
  887         } else
  888                 mtx_unlock(&np->n_mtx);
  889         mtx_lock(&nmp->nm_mtx);
  890         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  891             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  892                 mtx_unlock(&nmp->nm_mtx);
  893                 (void)nfs_fsinfo(nmp, vp, cred, td);
  894         } else
  895                 mtx_unlock(&nmp->nm_mtx);
  896 
  897         /*
  898          * Synchronously flush pending buffers if we are in synchronous
  899          * mode or if we are appending.
  900          */
  901         if (ioflag & (IO_APPEND | IO_SYNC)) {
  902                 mtx_lock(&np->n_mtx);
  903                 if (np->n_flag & NMODIFIED) {
  904                         mtx_unlock(&np->n_mtx);
  905 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  906                         /*
  907                          * Require non-blocking, synchronous writes to
  908                          * dirty files to inform the program it needs
  909                          * to fsync(2) explicitly.
  910                          */
  911                         if (ioflag & IO_NDELAY)
  912                                 return (EAGAIN);
  913 #endif
  914 flush_and_restart:
  915                         np->n_attrstamp = 0;
  916                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  917                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  918                         if (error)
  919                                 return (error);
  920                 } else
  921                         mtx_unlock(&np->n_mtx);
  922         }
  923 
  924         /*
  925          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  926          * get the append lock.
  927          */
  928         if (ioflag & IO_APPEND) {
  929                 np->n_attrstamp = 0;
  930                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  931                 error = VOP_GETATTR(vp, &vattr, cred);
  932                 if (error)
  933                         return (error);
  934                 mtx_lock(&np->n_mtx);
  935                 uio->uio_offset = np->n_size;
  936                 mtx_unlock(&np->n_mtx);
  937         }
  938 
  939         if (uio->uio_offset < 0)
  940                 return (EINVAL);
  941         if ((uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  942                 return (EFBIG);
  943         if (uio->uio_resid == 0)
  944                 return (0);
  945 
  946         if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  947                 return nfs_directio_write(vp, uio, cred, ioflag);
  948 
  949         /*
  950          * Maybe this should be above the vnode op call, but so long as
  951          * file servers have no limits, i don't think it matters
  952          */
  953         if (p != NULL) {
  954                 PROC_LOCK(p);
  955                 if (uio->uio_offset + uio->uio_resid >
  956                     lim_cur(p, RLIMIT_FSIZE)) {
  957                         psignal(p, SIGXFSZ);
  958                         PROC_UNLOCK(p);
  959                         return (EFBIG);
  960                 }
  961                 PROC_UNLOCK(p);
  962         }
  963 
  964         biosize = vp->v_mount->mnt_stat.f_iosize;
  965         /*
  966          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  967          * would exceed the local maximum per-file write commit size when
  968          * combined with those, we must decide whether to flush,
  969          * go synchronous, or return error.  We don't bother checking
  970          * IO_UNIT -- we just make all writes atomic anyway, as there's
  971          * no point optimizing for something that really won't ever happen.
  972          */
  973         if (!(ioflag & IO_SYNC)) {
  974                 int nflag;
  975 
  976                 mtx_lock(&np->n_mtx);
  977                 nflag = np->n_flag;
  978                 mtx_unlock(&np->n_mtx);         
  979                 int needrestart = 0;
  980                 if (nmp->nm_wcommitsize < uio->uio_resid) {
  981                         /*
  982                          * If this request could not possibly be completed
  983                          * without exceeding the maximum outstanding write
  984                          * commit size, see if we can convert it into a
  985                          * synchronous write operation.
  986                          */
  987                         if (ioflag & IO_NDELAY)
  988                                 return (EAGAIN);
  989                         ioflag |= IO_SYNC;
  990                         if (nflag & NMODIFIED)
  991                                 needrestart = 1;
  992                 } else if (nflag & NMODIFIED) {
  993                         int wouldcommit = 0;
  994                         BO_LOCK(&vp->v_bufobj);
  995                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  996                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  997                                     b_bobufs) {
  998                                         if (bp->b_flags & B_NEEDCOMMIT)
  999                                                 wouldcommit += bp->b_bcount;
 1000                                 }
 1001                         }
 1002                         BO_UNLOCK(&vp->v_bufobj);
 1003                         /*
 1004                          * Since we're not operating synchronously and
 1005                          * bypassing the buffer cache, we are in a commit
 1006                          * and holding all of these buffers whether
 1007                          * transmitted or not.  If not limited, this
 1008                          * will lead to the buffer cache deadlocking,
 1009                          * as no one else can flush our uncommitted buffers.
 1010                          */
 1011                         wouldcommit += uio->uio_resid;
 1012                         /*
 1013                          * If we would initially exceed the maximum
 1014                          * outstanding write commit size, flush and restart.
 1015                          */
 1016                         if (wouldcommit > nmp->nm_wcommitsize)
 1017                                 needrestart = 1;
 1018                 }
 1019                 if (needrestart)
 1020                         goto flush_and_restart;
 1021         }
 1022 
 1023         do {
 1024                 nfsstats.biocache_writes++;
 1025                 lbn = uio->uio_offset / biosize;
 1026                 on = uio->uio_offset & (biosize-1);
 1027                 n = min((unsigned)(biosize - on), uio->uio_resid);
 1028 again:
 1029                 /*
 1030                  * Handle direct append and file extension cases, calculate
 1031                  * unaligned buffer size.
 1032                  */
 1033                 mtx_lock(&np->n_mtx);
 1034                 if (uio->uio_offset == np->n_size && n) {
 1035                         mtx_unlock(&np->n_mtx);
 1036                         /*
 1037                          * Get the buffer (in its pre-append state to maintain
 1038                          * B_CACHE if it was previously set).  Resize the
 1039                          * nfsnode after we have locked the buffer to prevent
 1040                          * readers from reading garbage.
 1041                          */
 1042                         bcount = on;
 1043                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1044 
 1045                         if (bp != NULL) {
 1046                                 long save;
 1047 
 1048                                 mtx_lock(&np->n_mtx);
 1049                                 np->n_size = uio->uio_offset + n;
 1050                                 np->n_flag |= NMODIFIED;
 1051                                 vnode_pager_setsize(vp, np->n_size);
 1052                                 mtx_unlock(&np->n_mtx);
 1053 
 1054                                 save = bp->b_flags & B_CACHE;
 1055                                 bcount += n;
 1056                                 allocbuf(bp, bcount);
 1057                                 bp->b_flags |= save;
 1058                         }
 1059                 } else {
 1060                         /*
 1061                          * Obtain the locked cache block first, and then
 1062                          * adjust the file's size as appropriate.
 1063                          */
 1064                         bcount = on + n;
 1065                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1066                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1067                                         bcount = biosize;
 1068                                 else
 1069                                         bcount = np->n_size - (off_t)lbn * biosize;
 1070                         }
 1071                         mtx_unlock(&np->n_mtx);
 1072                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1073                         mtx_lock(&np->n_mtx);
 1074                         if (uio->uio_offset + n > np->n_size) {
 1075                                 np->n_size = uio->uio_offset + n;
 1076                                 np->n_flag |= NMODIFIED;
 1077                                 vnode_pager_setsize(vp, np->n_size);
 1078                         }
 1079                         mtx_unlock(&np->n_mtx);
 1080                 }
 1081 
 1082                 if (!bp) {
 1083                         error = nfs_sigintr(nmp, td);
 1084                         if (!error)
 1085                                 error = EINTR;
 1086                         break;
 1087                 }
 1088 
 1089                 /*
 1090                  * Issue a READ if B_CACHE is not set.  In special-append
 1091                  * mode, B_CACHE is based on the buffer prior to the write
 1092                  * op and is typically set, avoiding the read.  If a read
 1093                  * is required in special append mode, the server will
 1094                  * probably send us a short-read since we extended the file
 1095                  * on our end, resulting in b_resid == 0 and, thusly,
 1096                  * B_CACHE getting set.
 1097                  *
 1098                  * We can also avoid issuing the read if the write covers
 1099                  * the entire buffer.  We have to make sure the buffer state
 1100                  * is reasonable in this case since we will not be initiating
 1101                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1102                  * more information.
 1103                  *
 1104                  * B_CACHE may also be set due to the buffer being cached
 1105                  * normally.
 1106                  */
 1107 
 1108                 if (on == 0 && n == bcount) {
 1109                         bp->b_flags |= B_CACHE;
 1110                         bp->b_flags &= ~B_INVAL;
 1111                         bp->b_ioflags &= ~BIO_ERROR;
 1112                 }
 1113 
 1114                 if ((bp->b_flags & B_CACHE) == 0) {
 1115                         bp->b_iocmd = BIO_READ;
 1116                         vfs_busy_pages(bp, 0);
 1117                         error = nfs_doio(vp, bp, cred, td);
 1118                         if (error) {
 1119                                 brelse(bp);
 1120                                 break;
 1121                         }
 1122                 }
 1123                 if (bp->b_wcred == NOCRED)
 1124                         bp->b_wcred = crhold(cred);
 1125                 mtx_lock(&np->n_mtx);
 1126                 np->n_flag |= NMODIFIED;
 1127                 mtx_unlock(&np->n_mtx);
 1128 
 1129                 /*
 1130                  * If dirtyend exceeds file size, chop it down.  This should
 1131                  * not normally occur but there is an append race where it
 1132                  * might occur XXX, so we log it.
 1133                  *
 1134                  * If the chopping creates a reverse-indexed or degenerate
 1135                  * situation with dirtyoff/end, we 0 both of them.
 1136                  */
 1137 
 1138                 if (bp->b_dirtyend > bcount) {
 1139                         nfs_printf("NFS append race @%lx:%d\n",
 1140                             (long)bp->b_blkno * DEV_BSIZE,
 1141                             bp->b_dirtyend - bcount);
 1142                         bp->b_dirtyend = bcount;
 1143                 }
 1144 
 1145                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1146                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1147 
 1148                 /*
 1149                  * If the new write will leave a contiguous dirty
 1150                  * area, just update the b_dirtyoff and b_dirtyend,
 1151                  * otherwise force a write rpc of the old dirty area.
 1152                  *
 1153                  * While it is possible to merge discontiguous writes due to
 1154                  * our having a B_CACHE buffer ( and thus valid read data
 1155                  * for the hole), we don't because it could lead to
 1156                  * significant cache coherency problems with multiple clients,
 1157                  * especially if locking is implemented later on.
 1158                  *
 1159                  * as an optimization we could theoretically maintain
 1160                  * a linked list of discontinuous areas, but we would still
 1161                  * have to commit them separately so there isn't much
 1162                  * advantage to it except perhaps a bit of asynchronization.
 1163                  */
 1164 
 1165                 if (bp->b_dirtyend > 0 &&
 1166                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1167                         if (bwrite(bp) == EINTR) {
 1168                                 error = EINTR;
 1169                                 break;
 1170                         }
 1171                         goto again;
 1172                 }
 1173 
 1174                 error = uiomove((char *)bp->b_data + on, n, uio);
 1175 
 1176                 /*
 1177                  * Since this block is being modified, it must be written
 1178                  * again and not just committed.  Since write clustering does
 1179                  * not work for the stage 1 data write, only the stage 2
 1180                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1181                  */
 1182                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1183 
 1184                 if (error) {
 1185                         bp->b_ioflags |= BIO_ERROR;
 1186                         brelse(bp);
 1187                         break;
 1188                 }
 1189 
 1190                 /*
 1191                  * Only update dirtyoff/dirtyend if not a degenerate
 1192                  * condition.
 1193                  */
 1194                 if (n) {
 1195                         if (bp->b_dirtyend > 0) {
 1196                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1197                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1198                         } else {
 1199                                 bp->b_dirtyoff = on;
 1200                                 bp->b_dirtyend = on + n;
 1201                         }
 1202                         vfs_bio_set_valid(bp, on, n);
 1203                 }
 1204 
 1205                 /*
 1206                  * If IO_SYNC do bwrite().
 1207                  *
 1208                  * IO_INVAL appears to be unused.  The idea appears to be
 1209                  * to turn off caching in this case.  Very odd.  XXX
 1210                  */
 1211                 if ((ioflag & IO_SYNC)) {
 1212                         if (ioflag & IO_INVAL)
 1213                                 bp->b_flags |= B_NOCACHE;
 1214                         error = bwrite(bp);
 1215                         if (error)
 1216                                 break;
 1217                 } else if ((n + on) == biosize) {
 1218                         bp->b_flags |= B_ASYNC;
 1219                         (void) (nmp->nm_rpcops->nr_writebp)(bp, 0, NULL);
 1220                 } else {
 1221                         bdwrite(bp);
 1222                 }
 1223         } while (uio->uio_resid > 0 && n > 0);
 1224 
 1225         return (error);
 1226 }
 1227 
 1228 /*
 1229  * Get an nfs cache block.
 1230  *
 1231  * Allocate a new one if the block isn't currently in the cache
 1232  * and return the block marked busy. If the calling process is
 1233  * interrupted by a signal for an interruptible mount point, return
 1234  * NULL.
 1235  *
 1236  * The caller must carefully deal with the possible B_INVAL state of
 1237  * the buffer.  nfs_doio() clears B_INVAL (and nfs_asyncio() clears it
 1238  * indirectly), so synchronous reads can be issued without worrying about
 1239  * the B_INVAL state.  We have to be a little more careful when dealing
 1240  * with writes (see comments in nfs_write()) when extending a file past
 1241  * its EOF.
 1242  */
 1243 static struct buf *
 1244 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1245 {
 1246         struct buf *bp;
 1247         struct mount *mp;
 1248         struct nfsmount *nmp;
 1249 
 1250         mp = vp->v_mount;
 1251         nmp = VFSTONFS(mp);
 1252 
 1253         if (nmp->nm_flag & NFSMNT_INT) {
 1254                 sigset_t oldset;
 1255 
 1256                 nfs_set_sigmask(td, &oldset);
 1257                 bp = getblk(vp, bn, size, NFS_PCATCH, 0, 0);
 1258                 nfs_restore_sigmask(td, &oldset);
 1259                 while (bp == NULL) {
 1260                         if (nfs_sigintr(nmp, td))
 1261                                 return (NULL);
 1262                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1263                 }
 1264         } else {
 1265                 bp = getblk(vp, bn, size, 0, 0, 0);
 1266         }
 1267 
 1268         if (vp->v_type == VREG) {
 1269                 int biosize;
 1270 
 1271                 biosize = mp->mnt_stat.f_iosize;
 1272                 bp->b_blkno = bn * (biosize / DEV_BSIZE);
 1273         }
 1274         return (bp);
 1275 }
 1276 
 1277 /*
 1278  * Flush and invalidate all dirty buffers. If another process is already
 1279  * doing the flush, just wait for completion.
 1280  */
 1281 int
 1282 nfs_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1283 {
 1284         struct nfsnode *np = VTONFS(vp);
 1285         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1286         int error = 0, slpflag, slptimeo;
 1287         int old_lock = 0;
 1288 
 1289         ASSERT_VOP_LOCKED(vp, "nfs_vinvalbuf");
 1290 
 1291         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1292                 intrflg = 0;
 1293         if (intrflg) {
 1294                 slpflag = NFS_PCATCH;
 1295                 slptimeo = 2 * hz;
 1296         } else {
 1297                 slpflag = 0;
 1298                 slptimeo = 0;
 1299         }
 1300 
 1301         old_lock = nfs_upgrade_vnlock(vp);
 1302         if (vp->v_iflag & VI_DOOMED) {
 1303                 /*
 1304                  * Since vgonel() uses the generic vinvalbuf() to flush
 1305                  * dirty buffers and it does not call this function, it
 1306                  * is safe to just return OK when VI_DOOMED is set.
 1307                  */
 1308                 nfs_downgrade_vnlock(vp, old_lock);
 1309                 return (0);
 1310         }
 1311 
 1312         /*
 1313          * Now, flush as required.
 1314          */
 1315         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1316                 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
 1317                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1318                 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
 1319                 /*
 1320                  * If the page clean was interrupted, fail the invalidation.
 1321                  * Not doing so, we run the risk of losing dirty pages in the 
 1322                  * vinvalbuf() call below.
 1323                  */
 1324                 if (intrflg && (error = nfs_sigintr(nmp, td)))
 1325                         goto out;
 1326         }
 1327 
 1328         error = vinvalbuf(vp, flags, slpflag, 0);
 1329         while (error) {
 1330                 if (intrflg && (error = nfs_sigintr(nmp, td)))
 1331                         goto out;
 1332                 error = vinvalbuf(vp, flags, 0, slptimeo);
 1333         }
 1334         mtx_lock(&np->n_mtx);
 1335         if (np->n_directio_asyncwr == 0)
 1336                 np->n_flag &= ~NMODIFIED;
 1337         mtx_unlock(&np->n_mtx);
 1338 out:
 1339         nfs_downgrade_vnlock(vp, old_lock);
 1340         return error;
 1341 }
 1342 
 1343 /*
 1344  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1345  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1346  * are all hung on a dead server.
 1347  *
 1348  * Note: nfs_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1349  * is eventually dequeued by the async daemon, nfs_doio() *will*.
 1350  */
 1351 int
 1352 nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1353 {
 1354         int iod;
 1355         int gotiod;
 1356         int slpflag = 0;
 1357         int slptimeo = 0;
 1358         int error, error2;
 1359 
 1360         /*
 1361          * Commits are usually short and sweet so lets save some cpu and
 1362          * leave the async daemons for more important rpc's (such as reads
 1363          * and writes).
 1364          */
 1365         mtx_lock(&nfs_iod_mtx);
 1366         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1367             (nmp->nm_bufqiods > nfs_numasync / 2)) {
 1368                 mtx_unlock(&nfs_iod_mtx);
 1369                 return(EIO);
 1370         }
 1371 again:
 1372         if (nmp->nm_flag & NFSMNT_INT)
 1373                 slpflag = NFS_PCATCH;
 1374         gotiod = FALSE;
 1375 
 1376         /*
 1377          * Find a free iod to process this request.
 1378          */
 1379         for (iod = 0; iod < nfs_numasync; iod++)
 1380                 if (nfs_iodwant[iod]) {
 1381                         gotiod = TRUE;
 1382                         break;
 1383                 }
 1384 
 1385         /*
 1386          * Try to create one if none are free.
 1387          */
 1388         if (!gotiod) {
 1389                 iod = nfs_nfsiodnew();
 1390                 if (iod != -1)
 1391                         gotiod = TRUE;
 1392         }
 1393 
 1394         if (gotiod) {
 1395                 /*
 1396                  * Found one, so wake it up and tell it which
 1397                  * mount to process.
 1398                  */
 1399                 NFS_DPF(ASYNCIO, ("nfs_asyncio: waking iod %d for mount %p\n",
 1400                     iod, nmp));
 1401                 nfs_iodwant[iod] = NULL;
 1402                 nfs_iodmount[iod] = nmp;
 1403                 nmp->nm_bufqiods++;
 1404                 wakeup(&nfs_iodwant[iod]);
 1405         }
 1406 
 1407         /*
 1408          * If none are free, we may already have an iod working on this mount
 1409          * point.  If so, it will process our request.
 1410          */
 1411         if (!gotiod) {
 1412                 if (nmp->nm_bufqiods > 0) {
 1413                         NFS_DPF(ASYNCIO,
 1414                                 ("nfs_asyncio: %d iods are already processing mount %p\n",
 1415                                  nmp->nm_bufqiods, nmp));
 1416                         gotiod = TRUE;
 1417                 }
 1418         }
 1419 
 1420         /*
 1421          * If we have an iod which can process the request, then queue
 1422          * the buffer.
 1423          */
 1424         if (gotiod) {
 1425                 /*
 1426                  * Ensure that the queue never grows too large.  We still want
 1427                  * to asynchronize so we block rather then return EIO.
 1428                  */
 1429                 while (nmp->nm_bufqlen >= 2*nfs_numasync) {
 1430                         NFS_DPF(ASYNCIO,
 1431                                 ("nfs_asyncio: waiting for mount %p queue to drain\n", nmp));
 1432                         nmp->nm_bufqwant = TRUE;
 1433                         error = nfs_msleep(td, &nmp->nm_bufq, &nfs_iod_mtx, 
 1434                                            slpflag | PRIBIO,
 1435                                            "nfsaio", slptimeo);
 1436                         if (error) {
 1437                                 error2 = nfs_sigintr(nmp, td);
 1438                                 if (error2) {
 1439                                         mtx_unlock(&nfs_iod_mtx);                                       
 1440                                         return (error2);
 1441                                 }
 1442                                 if (slpflag == NFS_PCATCH) {
 1443                                         slpflag = 0;
 1444                                         slptimeo = 2 * hz;
 1445                                 }
 1446                         }
 1447                         /*
 1448                          * We might have lost our iod while sleeping,
 1449                          * so check and loop if nescessary.
 1450                          */
 1451                         if (nmp->nm_bufqiods == 0) {
 1452                                 NFS_DPF(ASYNCIO,
 1453                                         ("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1454                                 goto again;
 1455                         }
 1456                 }
 1457 
 1458                 /* We might have lost our nfsiod */
 1459                 if (nmp->nm_bufqiods == 0) {
 1460                         NFS_DPF(ASYNCIO,
 1461                                 ("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1462                         goto again;
 1463                 }
 1464 
 1465                 if (bp->b_iocmd == BIO_READ) {
 1466                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1467                                 bp->b_rcred = crhold(cred);
 1468                 } else {
 1469                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1470                                 bp->b_wcred = crhold(cred);
 1471                 }
 1472 
 1473                 if (bp->b_flags & B_REMFREE)
 1474                         bremfreef(bp);
 1475                 BUF_KERNPROC(bp);
 1476                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1477                 nmp->nm_bufqlen++;
 1478                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1479                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);                   
 1480                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1481                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1482                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1483                 }
 1484                 mtx_unlock(&nfs_iod_mtx);
 1485                 return (0);
 1486         }
 1487 
 1488         mtx_unlock(&nfs_iod_mtx);
 1489 
 1490         /*
 1491          * All the iods are busy on other mounts, so return EIO to
 1492          * force the caller to process the i/o synchronously.
 1493          */
 1494         NFS_DPF(ASYNCIO, ("nfs_asyncio: no iods available, i/o is synchronous\n"));
 1495         return (EIO);
 1496 }
 1497 
 1498 void
 1499 nfs_doio_directwrite(struct buf *bp)
 1500 {
 1501         int iomode, must_commit;
 1502         struct uio *uiop = (struct uio *)bp->b_caller1;
 1503         char *iov_base = uiop->uio_iov->iov_base;
 1504         struct nfsmount *nmp = VFSTONFS(bp->b_vp->v_mount);
 1505         
 1506         iomode = NFSV3WRITE_FILESYNC;
 1507         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1508         (nmp->nm_rpcops->nr_writerpc)(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
 1509         KASSERT((must_commit == 0), ("nfs_doio_directwrite: Did not commit write"));
 1510         free(iov_base, M_NFSDIRECTIO);
 1511         free(uiop->uio_iov, M_NFSDIRECTIO);
 1512         free(uiop, M_NFSDIRECTIO);
 1513         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1514                 struct nfsnode *np = VTONFS(bp->b_vp);
 1515                 mtx_lock(&np->n_mtx);
 1516                 np->n_directio_asyncwr--;
 1517                 if (np->n_directio_asyncwr == 0) {
 1518                         VTONFS(bp->b_vp)->n_flag &= ~NMODIFIED;
 1519                         if ((np->n_flag & NFSYNCWAIT)) {
 1520                                 np->n_flag &= ~NFSYNCWAIT;
 1521                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1522                         }
 1523                 }
 1524                 mtx_unlock(&np->n_mtx);
 1525         }
 1526         bp->b_vp = NULL;
 1527         relpbuf(bp, &nfs_pbuf_freecnt);
 1528 }
 1529 
 1530 /*
 1531  * Do an I/O operation to/from a cache block. This may be called
 1532  * synchronously or from an nfsiod.
 1533  */
 1534 int
 1535 nfs_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
 1536 {
 1537         struct uio *uiop;
 1538         struct nfsnode *np;
 1539         struct nfsmount *nmp;
 1540         int error = 0, iomode, must_commit = 0;
 1541         struct uio uio;
 1542         struct iovec io;
 1543         struct proc *p = td ? td->td_proc : NULL;
 1544         uint8_t iocmd;
 1545         
 1546         np = VTONFS(vp);
 1547         nmp = VFSTONFS(vp->v_mount);
 1548         uiop = &uio;
 1549         uiop->uio_iov = &io;
 1550         uiop->uio_iovcnt = 1;
 1551         uiop->uio_segflg = UIO_SYSSPACE;
 1552         uiop->uio_td = td;
 1553 
 1554         /*
 1555          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1556          * do this here so we do not have to do it in all the code that
 1557          * calls us.
 1558          */
 1559         bp->b_flags &= ~B_INVAL;
 1560         bp->b_ioflags &= ~BIO_ERROR;
 1561 
 1562         KASSERT(!(bp->b_flags & B_DONE), ("nfs_doio: bp %p already marked done", bp));
 1563         iocmd = bp->b_iocmd;
 1564         if (iocmd == BIO_READ) {
 1565             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1566             io.iov_base = bp->b_data;
 1567             uiop->uio_rw = UIO_READ;
 1568 
 1569             switch (vp->v_type) {
 1570             case VREG:
 1571                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1572                 nfsstats.read_bios++;
 1573                 error = (nmp->nm_rpcops->nr_readrpc)(vp, uiop, cr);
 1574 
 1575                 if (!error) {
 1576                     if (uiop->uio_resid) {
 1577                         /*
 1578                          * If we had a short read with no error, we must have
 1579                          * hit a file hole.  We should zero-fill the remainder.
 1580                          * This can also occur if the server hits the file EOF.
 1581                          *
 1582                          * Holes used to be able to occur due to pending
 1583                          * writes, but that is not possible any longer.
 1584                          */
 1585                         int nread = bp->b_bcount - uiop->uio_resid;
 1586                         int left  = uiop->uio_resid;
 1587 
 1588                         if (left > 0)
 1589                                 bzero((char *)bp->b_data + nread, left);
 1590                         uiop->uio_resid = 0;
 1591                     }
 1592                 }
 1593                 /* ASSERT_VOP_LOCKED(vp, "nfs_doio"); */
 1594                 if (p && (vp->v_vflag & VV_TEXT)) {
 1595                         mtx_lock(&np->n_mtx);
 1596                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.va_mtime)) {
 1597                                 mtx_unlock(&np->n_mtx);
 1598                                 PROC_LOCK(p);
 1599                                 killproc(p, "text file modification");
 1600                                 PROC_UNLOCK(p);
 1601                         } else
 1602                                 mtx_unlock(&np->n_mtx);
 1603                 }
 1604                 break;
 1605             case VLNK:
 1606                 uiop->uio_offset = (off_t)0;
 1607                 nfsstats.readlink_bios++;
 1608                 error = (nmp->nm_rpcops->nr_readlinkrpc)(vp, uiop, cr);
 1609                 break;
 1610             case VDIR:
 1611                 nfsstats.readdir_bios++;
 1612                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1613                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1614                         error = nfs_readdirplusrpc(vp, uiop, cr);
 1615                         if (error == NFSERR_NOTSUPP)
 1616                                 nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1617                 }
 1618                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1619                         error = nfs_readdirrpc(vp, uiop, cr);
 1620                 /*
 1621                  * end-of-directory sets B_INVAL but does not generate an
 1622                  * error.
 1623                  */
 1624                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1625                         bp->b_flags |= B_INVAL;
 1626                 break;
 1627             default:
 1628                 nfs_printf("nfs_doio:  type %x unexpected\n", vp->v_type);
 1629                 break;
 1630             };
 1631             if (error) {
 1632                 bp->b_ioflags |= BIO_ERROR;
 1633                 bp->b_error = error;
 1634             }
 1635         } else {
 1636             /*
 1637              * If we only need to commit, try to commit
 1638              */
 1639             if (bp->b_flags & B_NEEDCOMMIT) {
 1640                     int retv;
 1641                     off_t off;
 1642 
 1643                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1644                     retv = (nmp->nm_rpcops->nr_commit)(
 1645                                 vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1646                                 bp->b_wcred, td);
 1647                     if (retv == 0) {
 1648                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1649                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1650                             bp->b_resid = 0;
 1651                             bufdone(bp);
 1652                             return (0);
 1653                     }
 1654                     if (retv == NFSERR_STALEWRITEVERF) {
 1655                             nfs_clearcommit(vp->v_mount);
 1656                     }
 1657             }
 1658 
 1659             /*
 1660              * Setup for actual write
 1661              */
 1662             mtx_lock(&np->n_mtx);
 1663             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1664                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1665             mtx_unlock(&np->n_mtx);
 1666 
 1667             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1668                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1669                     - bp->b_dirtyoff;
 1670                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1671                     + bp->b_dirtyoff;
 1672                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1673                 uiop->uio_rw = UIO_WRITE;
 1674                 nfsstats.write_bios++;
 1675 
 1676                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1677                     iomode = NFSV3WRITE_UNSTABLE;
 1678                 else
 1679                     iomode = NFSV3WRITE_FILESYNC;
 1680 
 1681                 error = (nmp->nm_rpcops->nr_writerpc)(vp, uiop, cr, &iomode, &must_commit);
 1682 
 1683                 /*
 1684                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1685                  * to cluster the buffers needing commit.  This will allow
 1686                  * the system to submit a single commit rpc for the whole
 1687                  * cluster.  We can do this even if the buffer is not 100%
 1688                  * dirty (relative to the NFS blocksize), so we optimize the
 1689                  * append-to-file-case.
 1690                  *
 1691                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1692                  * cleared because write clustering only works for commit
 1693                  * rpc's, not for the data portion of the write).
 1694                  */
 1695 
 1696                 if (!error && iomode == NFSV3WRITE_UNSTABLE) {
 1697                     bp->b_flags |= B_NEEDCOMMIT;
 1698                     if (bp->b_dirtyoff == 0
 1699                         && bp->b_dirtyend == bp->b_bcount)
 1700                         bp->b_flags |= B_CLUSTEROK;
 1701                 } else {
 1702                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1703                 }
 1704 
 1705                 /*
 1706                  * For an interrupted write, the buffer is still valid
 1707                  * and the write hasn't been pushed to the server yet,
 1708                  * so we can't set BIO_ERROR and report the interruption
 1709                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1710                  * is not relevant, so the rpc attempt is essentially
 1711                  * a noop.  For the case of a V3 write rpc not being
 1712                  * committed to stable storage, the block is still
 1713                  * dirty and requires either a commit rpc or another
 1714                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1715                  * the block is reused. This is indicated by setting
 1716                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1717                  *
 1718                  * If the buffer is marked B_PAGING, it does not reside on
 1719                  * the vp's paging queues so we cannot call bdirty().  The
 1720                  * bp in this case is not an NFS cache block so we should
 1721                  * be safe. XXX
 1722                  *
 1723                  * The logic below breaks up errors into recoverable and 
 1724                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1725                  * and keep the buffer around for potential write retries.
 1726                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1727                  * and save the error in the nfsnode. This is less than ideal 
 1728                  * but necessary. Keeping such buffers around could potentially
 1729                  * cause buffer exhaustion eventually (they can never be written
 1730                  * out, so will get constantly be re-dirtied). It also causes
 1731                  * all sorts of vfs panics. For non-recoverable write errors, 
 1732                  * also invalidate the attrcache, so we'll be forced to go over
 1733                  * the wire for this object, returning an error to user on next
 1734                  * call (most of the time).
 1735                  */
 1736                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1737                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1738                         int s;
 1739 
 1740                         s = splbio();
 1741                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1742                         if ((bp->b_flags & B_PAGING) == 0) {
 1743                             bdirty(bp);
 1744                             bp->b_flags &= ~B_DONE;
 1745                         }
 1746                         if (error && (bp->b_flags & B_ASYNC) == 0)
 1747                             bp->b_flags |= B_EINTR;
 1748                         splx(s);
 1749                 } else {
 1750                     if (error) {
 1751                         bp->b_ioflags |= BIO_ERROR;
 1752                         bp->b_flags |= B_INVAL;
 1753                         bp->b_error = np->n_error = error;
 1754                         mtx_lock(&np->n_mtx);
 1755                         np->n_flag |= NWRITEERR;
 1756                         np->n_attrstamp = 0;
 1757                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 1758                         mtx_unlock(&np->n_mtx);
 1759                     }
 1760                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1761                 }
 1762             } else {
 1763                 bp->b_resid = 0;
 1764                 bufdone(bp);
 1765                 return (0);
 1766             }
 1767         }
 1768         bp->b_resid = uiop->uio_resid;
 1769         if (must_commit)
 1770             nfs_clearcommit(vp->v_mount);
 1771         bufdone(bp);
 1772         return (error);
 1773 }
 1774 
 1775 /*
 1776  * Used to aid in handling ftruncate() operations on the NFS client side.
 1777  * Truncation creates a number of special problems for NFS.  We have to
 1778  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1779  * we have to properly handle VM pages or (potentially dirty) buffers
 1780  * that straddle the truncation point.
 1781  */
 1782 
 1783 int
 1784 nfs_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1785 {
 1786         struct nfsnode *np = VTONFS(vp);
 1787         u_quad_t tsize;
 1788         int biosize = vp->v_mount->mnt_stat.f_iosize;
 1789         int error = 0;
 1790 
 1791         mtx_lock(&np->n_mtx);
 1792         tsize = np->n_size;
 1793         np->n_size = nsize;
 1794         mtx_unlock(&np->n_mtx);
 1795 
 1796         if (nsize < tsize) {
 1797                 struct buf *bp;
 1798                 daddr_t lbn;
 1799                 int bufsize;
 1800 
 1801                 /*
 1802                  * vtruncbuf() doesn't get the buffer overlapping the 
 1803                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1804                  * buffer that now needs to be truncated.
 1805                  */
 1806                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1807                 lbn = nsize / biosize;
 1808                 bufsize = nsize & (biosize - 1);
 1809                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1810                 if (!bp)
 1811                         return EINTR;
 1812                 if (bp->b_dirtyoff > bp->b_bcount)
 1813                         bp->b_dirtyoff = bp->b_bcount;
 1814                 if (bp->b_dirtyend > bp->b_bcount)
 1815                         bp->b_dirtyend = bp->b_bcount;
 1816                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1817                 brelse(bp);
 1818         } else {
 1819                 vnode_pager_setsize(vp, nsize);
 1820         }
 1821         return(error);
 1822 }
 1823 

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