The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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/10.4/sys/nfsclient/nfs_bio.c 249623 2013-04-18 13:09:04Z rmacklem $");
   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/rwlock.h>
   49 #include <sys/vmmeter.h>
   50 #include <sys/vnode.h>
   51 
   52 #include <vm/vm.h>
   53 #include <vm/vm_param.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 <nfs/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_WLOCK(object);
  133         if (pages[ap->a_reqpage]->valid != 0) {
  134                 for (i = 0; i < npages; ++i) {
  135                         if (i != ap->a_reqpage) {
  136                                 vm_page_lock(pages[i]);
  137                                 vm_page_free(pages[i]);
  138                                 vm_page_unlock(pages[i]);
  139                         }
  140                 }
  141                 VM_OBJECT_WUNLOCK(object);
  142                 return (0);
  143         }
  144         VM_OBJECT_WUNLOCK(object);
  145 
  146         /*
  147          * We use only the kva address for the buffer, but this is extremely
  148          * convienient and fast.
  149          */
  150         bp = getpbuf(&nfs_pbuf_freecnt);
  151 
  152         kva = (vm_offset_t) bp->b_data;
  153         pmap_qenter(kva, pages, npages);
  154         PCPU_INC(cnt.v_vnodein);
  155         PCPU_ADD(cnt.v_vnodepgsin, npages);
  156 
  157         iov.iov_base = (caddr_t) kva;
  158         iov.iov_len = count;
  159         uio.uio_iov = &iov;
  160         uio.uio_iovcnt = 1;
  161         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  162         uio.uio_resid = count;
  163         uio.uio_segflg = UIO_SYSSPACE;
  164         uio.uio_rw = UIO_READ;
  165         uio.uio_td = td;
  166 
  167         error = (nmp->nm_rpcops->nr_readrpc)(vp, &uio, cred);
  168         pmap_qremove(kva, npages);
  169 
  170         relpbuf(bp, &nfs_pbuf_freecnt);
  171 
  172         if (error && (uio.uio_resid == count)) {
  173                 nfs_printf("nfs_getpages: error %d\n", error);
  174                 VM_OBJECT_WLOCK(object);
  175                 for (i = 0; i < npages; ++i) {
  176                         if (i != ap->a_reqpage) {
  177                                 vm_page_lock(pages[i]);
  178                                 vm_page_free(pages[i]);
  179                                 vm_page_unlock(pages[i]);
  180                         }
  181                 }
  182                 VM_OBJECT_WUNLOCK(object);
  183                 return (VM_PAGER_ERROR);
  184         }
  185 
  186         /*
  187          * Calculate the number of bytes read and validate only that number
  188          * of bytes.  Note that due to pending writes, size may be 0.  This
  189          * does not mean that the remaining data is invalid!
  190          */
  191 
  192         size = count - uio.uio_resid;
  193         VM_OBJECT_WLOCK(object);
  194         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  195                 vm_page_t m;
  196                 nextoff = toff + PAGE_SIZE;
  197                 m = pages[i];
  198 
  199                 if (nextoff <= size) {
  200                         /*
  201                          * Read operation filled an entire page
  202                          */
  203                         m->valid = VM_PAGE_BITS_ALL;
  204                         KASSERT(m->dirty == 0,
  205                             ("nfs_getpages: page %p is dirty", m));
  206                 } else if (size > toff) {
  207                         /*
  208                          * Read operation filled a partial page.
  209                          */
  210                         m->valid = 0;
  211                         vm_page_set_valid_range(m, 0, size - toff);
  212                         KASSERT(m->dirty == 0,
  213                             ("nfs_getpages: page %p is dirty", m));
  214                 } else {
  215                         /*
  216                          * Read operation was short.  If no error
  217                          * occured we may have hit a zero-fill
  218                          * section.  We leave valid set to 0, and page
  219                          * is freed by vm_page_readahead_finish() if
  220                          * its index is not equal to requested, or
  221                          * page is zeroed and set valid by
  222                          * vm_pager_get_pages() for requested page.
  223                          */
  224                         ;
  225                 }
  226                 if (i != ap->a_reqpage)
  227                         vm_page_readahead_finish(m);
  228         }
  229         VM_OBJECT_WUNLOCK(object);
  230         return (0);
  231 }
  232 
  233 /*
  234  * Vnode op for VM putpages.
  235  */
  236 int
  237 nfs_putpages(struct vop_putpages_args *ap)
  238 {
  239         struct uio uio;
  240         struct iovec iov;
  241         vm_offset_t kva;
  242         struct buf *bp;
  243         int iomode, must_commit, i, error, npages, count;
  244         off_t offset;
  245         int *rtvals;
  246         struct vnode *vp;
  247         struct thread *td;
  248         struct ucred *cred;
  249         struct nfsmount *nmp;
  250         struct nfsnode *np;
  251         vm_page_t *pages;
  252 
  253         vp = ap->a_vp;
  254         np = VTONFS(vp);
  255         td = curthread;                         /* XXX */
  256         /* Set the cred to n_writecred for the write rpcs. */
  257         if (np->n_writecred != NULL)
  258                 cred = crhold(np->n_writecred);
  259         else
  260                 cred = crhold(curthread->td_ucred);     /* XXX */
  261         nmp = VFSTONFS(vp->v_mount);
  262         pages = ap->a_m;
  263         count = ap->a_count;
  264         rtvals = ap->a_rtvals;
  265         npages = btoc(count);
  266         offset = IDX_TO_OFF(pages[0]->pindex);
  267         
  268         mtx_lock(&nmp->nm_mtx);
  269         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  270             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  271                 mtx_unlock(&nmp->nm_mtx);
  272                 (void)nfs_fsinfo(nmp, vp, cred, td);
  273         } else
  274                 mtx_unlock(&nmp->nm_mtx);
  275 
  276         mtx_lock(&np->n_mtx);
  277         if (nfs_directio_enable && !nfs_directio_allow_mmap && 
  278             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  279                 mtx_unlock(&np->n_mtx);         
  280                 nfs_printf("nfs_putpages: called on noncache-able vnode??\n");
  281                 mtx_lock(&np->n_mtx);
  282         }
  283 
  284         for (i = 0; i < npages; i++)
  285                 rtvals[i] = VM_PAGER_ERROR;
  286 
  287         /*
  288          * When putting pages, do not extend file past EOF.
  289          */
  290         if (offset + count > np->n_size) {
  291                 count = np->n_size - offset;
  292                 if (count < 0)
  293                         count = 0;
  294         }
  295         mtx_unlock(&np->n_mtx);
  296 
  297         /*
  298          * We use only the kva address for the buffer, but this is extremely
  299          * convienient and fast.
  300          */
  301         bp = getpbuf(&nfs_pbuf_freecnt);
  302 
  303         kva = (vm_offset_t) bp->b_data;
  304         pmap_qenter(kva, pages, npages);
  305         PCPU_INC(cnt.v_vnodeout);
  306         PCPU_ADD(cnt.v_vnodepgsout, count);
  307 
  308         iov.iov_base = (caddr_t) kva;
  309         iov.iov_len = count;
  310         uio.uio_iov = &iov;
  311         uio.uio_iovcnt = 1;
  312         uio.uio_offset = offset;
  313         uio.uio_resid = count;
  314         uio.uio_segflg = UIO_SYSSPACE;
  315         uio.uio_rw = UIO_WRITE;
  316         uio.uio_td = td;
  317 
  318         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  319             iomode = NFSV3WRITE_UNSTABLE;
  320         else
  321             iomode = NFSV3WRITE_FILESYNC;
  322 
  323         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, &iomode, &must_commit);
  324         crfree(cred);
  325 
  326         pmap_qremove(kva, npages);
  327         relpbuf(bp, &nfs_pbuf_freecnt);
  328 
  329         if (!error) {
  330                 vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
  331                 if (must_commit) {
  332                         nfs_clearcommit(vp->v_mount);
  333                 }
  334         }
  335         return rtvals[0];
  336 }
  337 
  338 /*
  339  * For nfs, cache consistency can only be maintained approximately.
  340  * Although RFC1094 does not specify the criteria, the following is
  341  * believed to be compatible with the reference port.
  342  * For nfs:
  343  * If the file's modify time on the server has changed since the
  344  * last read rpc or you have written to the file,
  345  * you may have lost data cache consistency with the
  346  * server, so flush all of the file's data out of the cache.
  347  * Then force a getattr rpc to ensure that you have up to date
  348  * attributes.
  349  * NB: This implies that cache data can be read when up to
  350  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  351  * attributes this could be forced by setting n_attrstamp to 0 before
  352  * the VOP_GETATTR() call.
  353  */
  354 static inline int
  355 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  356 {
  357         int error = 0;
  358         struct vattr vattr;
  359         struct nfsnode *np = VTONFS(vp);
  360         int old_lock;
  361         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  362         
  363         /*
  364          * Grab the exclusive lock before checking whether the cache is
  365          * consistent.
  366          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  367          * But for now, this suffices.
  368          */
  369         old_lock = nfs_upgrade_vnlock(vp);
  370         if (vp->v_iflag & VI_DOOMED) {
  371                 nfs_downgrade_vnlock(vp, old_lock);
  372                 return (EBADF);
  373         }
  374                 
  375         mtx_lock(&np->n_mtx);
  376         if (np->n_flag & NMODIFIED) {
  377                 mtx_unlock(&np->n_mtx);
  378                 if (vp->v_type != VREG) {
  379                         if (vp->v_type != VDIR)
  380                                 panic("nfs: bioread, not dir");
  381                         (nmp->nm_rpcops->nr_invaldir)(vp);
  382                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  383                         if (error)
  384                                 goto out;
  385                 }
  386                 np->n_attrstamp = 0;
  387                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  388                 error = VOP_GETATTR(vp, &vattr, cred);
  389                 if (error)
  390                         goto out;
  391                 mtx_lock(&np->n_mtx);
  392                 np->n_mtime = vattr.va_mtime;
  393                 mtx_unlock(&np->n_mtx);
  394         } else {
  395                 mtx_unlock(&np->n_mtx);
  396                 error = VOP_GETATTR(vp, &vattr, cred);
  397                 if (error)
  398                         return (error);
  399                 mtx_lock(&np->n_mtx);
  400                 if ((np->n_flag & NSIZECHANGED)
  401                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  402                         mtx_unlock(&np->n_mtx);
  403                         if (vp->v_type == VDIR)
  404                                 (nmp->nm_rpcops->nr_invaldir)(vp);
  405                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  406                         if (error)
  407                                 goto out;
  408                         mtx_lock(&np->n_mtx);
  409                         np->n_mtime = vattr.va_mtime;
  410                         np->n_flag &= ~NSIZECHANGED;
  411                 }
  412                 mtx_unlock(&np->n_mtx);
  413         }
  414 out:    
  415         nfs_downgrade_vnlock(vp, old_lock);
  416         return error;
  417 }
  418 
  419 /*
  420  * Vnode op for read using bio
  421  */
  422 int
  423 nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  424 {
  425         struct nfsnode *np = VTONFS(vp);
  426         int biosize, i;
  427         struct buf *bp, *rabp;
  428         struct thread *td;
  429         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  430         daddr_t lbn, rabn;
  431         off_t end;
  432         int bcount;
  433         int seqcount;
  434         int nra, error = 0, n = 0, on = 0;
  435 
  436         KASSERT(uio->uio_rw == UIO_READ, ("nfs_read mode"));
  437         if (uio->uio_resid == 0)
  438                 return (0);
  439         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  440                 return (EINVAL);
  441         td = uio->uio_td;
  442 
  443         mtx_lock(&nmp->nm_mtx);
  444         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  445             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  446                 mtx_unlock(&nmp->nm_mtx);
  447                 (void)nfs_fsinfo(nmp, vp, cred, td);
  448         } else
  449                 mtx_unlock(&nmp->nm_mtx);               
  450 
  451         end = uio->uio_offset + uio->uio_resid;
  452         if (vp->v_type != VDIR &&
  453             (end > nmp->nm_maxfilesize || end < uio->uio_offset))
  454                 return (EFBIG);
  455 
  456         if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  457                 /* No caching/ no readaheads. Just read data into the user buffer */
  458                 return nfs_readrpc(vp, uio, cred);
  459 
  460         biosize = vp->v_bufobj.bo_bsize;
  461         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  462         
  463         error = nfs_bioread_check_cons(vp, td, cred);
  464         if (error)
  465                 return error;
  466 
  467         do {
  468             u_quad_t nsize;
  469                         
  470             mtx_lock(&np->n_mtx);
  471             nsize = np->n_size;
  472             mtx_unlock(&np->n_mtx);                 
  473 
  474             switch (vp->v_type) {
  475             case VREG:
  476                 nfsstats.biocache_reads++;
  477                 lbn = uio->uio_offset / biosize;
  478                 on = uio->uio_offset - (lbn * biosize);
  479 
  480                 /*
  481                  * Start the read ahead(s), as required.
  482                  */
  483                 if (nmp->nm_readahead > 0) {
  484                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  485                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  486                         rabn = lbn + 1 + nra;
  487                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  488                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  489                             if (!rabp) {
  490                                 error = nfs_sigintr(nmp, td);
  491                                 return (error ? error : EINTR);
  492                             }
  493                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  494                                 rabp->b_flags |= B_ASYNC;
  495                                 rabp->b_iocmd = BIO_READ;
  496                                 vfs_busy_pages(rabp, 0);
  497                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  498                                     rabp->b_flags |= B_INVAL;
  499                                     rabp->b_ioflags |= BIO_ERROR;
  500                                     vfs_unbusy_pages(rabp);
  501                                     brelse(rabp);
  502                                     break;
  503                                 }
  504                             } else {
  505                                 brelse(rabp);
  506                             }
  507                         }
  508                     }
  509                 }
  510 
  511                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  512                 bcount = biosize;
  513                 if ((off_t)lbn * biosize >= nsize) {
  514                         bcount = 0;
  515                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  516                         bcount = nsize - (off_t)lbn * biosize;
  517                 }
  518                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  519 
  520                 if (!bp) {
  521                         error = nfs_sigintr(nmp, td);
  522                         return (error ? error : EINTR);
  523                 }
  524 
  525                 /*
  526                  * If B_CACHE is not set, we must issue the read.  If this
  527                  * fails, we return an error.
  528                  */
  529 
  530                 if ((bp->b_flags & B_CACHE) == 0) {
  531                     bp->b_iocmd = BIO_READ;
  532                     vfs_busy_pages(bp, 0);
  533                     error = nfs_doio(vp, bp, cred, td);
  534                     if (error) {
  535                         brelse(bp);
  536                         return (error);
  537                     }
  538                 }
  539 
  540                 /*
  541                  * on is the offset into the current bp.  Figure out how many
  542                  * bytes we can copy out of the bp.  Note that bcount is
  543                  * NOT DEV_BSIZE aligned.
  544                  *
  545                  * Then figure out how many bytes we can copy into the uio.
  546                  */
  547 
  548                 n = 0;
  549                 if (on < bcount)
  550                         n = MIN((unsigned)(bcount - on), uio->uio_resid);
  551                 break;
  552             case VLNK:
  553                 nfsstats.biocache_readlinks++;
  554                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  555                 if (!bp) {
  556                         error = nfs_sigintr(nmp, td);
  557                         return (error ? error : EINTR);
  558                 }
  559                 if ((bp->b_flags & B_CACHE) == 0) {
  560                     bp->b_iocmd = BIO_READ;
  561                     vfs_busy_pages(bp, 0);
  562                     error = nfs_doio(vp, bp, cred, td);
  563                     if (error) {
  564                         bp->b_ioflags |= BIO_ERROR;
  565                         brelse(bp);
  566                         return (error);
  567                     }
  568                 }
  569                 n = MIN(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  570                 on = 0;
  571                 break;
  572             case VDIR:
  573                 nfsstats.biocache_readdirs++;
  574                 if (np->n_direofoffset
  575                     && uio->uio_offset >= np->n_direofoffset) {
  576                     return (0);
  577                 }
  578                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  579                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  580                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  581                 if (!bp) {
  582                     error = nfs_sigintr(nmp, td);
  583                     return (error ? error : EINTR);
  584                 }
  585                 if ((bp->b_flags & B_CACHE) == 0) {
  586                     bp->b_iocmd = BIO_READ;
  587                     vfs_busy_pages(bp, 0);
  588                     error = nfs_doio(vp, bp, cred, td);
  589                     if (error) {
  590                             brelse(bp);
  591                     }
  592                     while (error == NFSERR_BAD_COOKIE) {
  593                         (nmp->nm_rpcops->nr_invaldir)(vp);
  594                         error = nfs_vinvalbuf(vp, 0, td, 1);
  595                         /*
  596                          * Yuck! The directory has been modified on the
  597                          * server. The only way to get the block is by
  598                          * reading from the beginning to get all the
  599                          * offset cookies.
  600                          *
  601                          * Leave the last bp intact unless there is an error.
  602                          * Loop back up to the while if the error is another
  603                          * NFSERR_BAD_COOKIE (double yuch!).
  604                          */
  605                         for (i = 0; i <= lbn && !error; i++) {
  606                             if (np->n_direofoffset
  607                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  608                                     return (0);
  609                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  610                             if (!bp) {
  611                                 error = nfs_sigintr(nmp, td);
  612                                 return (error ? error : EINTR);
  613                             }
  614                             if ((bp->b_flags & B_CACHE) == 0) {
  615                                     bp->b_iocmd = BIO_READ;
  616                                     vfs_busy_pages(bp, 0);
  617                                     error = nfs_doio(vp, bp, cred, td);
  618                                     /*
  619                                      * no error + B_INVAL == directory EOF,
  620                                      * use the block.
  621                                      */
  622                                     if (error == 0 && (bp->b_flags & B_INVAL))
  623                                             break;
  624                             }
  625                             /*
  626                              * An error will throw away the block and the
  627                              * for loop will break out.  If no error and this
  628                              * is not the block we want, we throw away the
  629                              * block and go for the next one via the for loop.
  630                              */
  631                             if (error || i < lbn)
  632                                     brelse(bp);
  633                         }
  634                     }
  635                     /*
  636                      * The above while is repeated if we hit another cookie
  637                      * error.  If we hit an error and it wasn't a cookie error,
  638                      * we give up.
  639                      */
  640                     if (error)
  641                             return (error);
  642                 }
  643 
  644                 /*
  645                  * If not eof and read aheads are enabled, start one.
  646                  * (You need the current block first, so that you have the
  647                  *  directory offset cookie of the next block.)
  648                  */
  649                 if (nmp->nm_readahead > 0 &&
  650                     (bp->b_flags & B_INVAL) == 0 &&
  651                     (np->n_direofoffset == 0 ||
  652                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  653                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  654                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  655                         if (rabp) {
  656                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  657                                 rabp->b_flags |= B_ASYNC;
  658                                 rabp->b_iocmd = BIO_READ;
  659                                 vfs_busy_pages(rabp, 0);
  660                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  661                                     rabp->b_flags |= B_INVAL;
  662                                     rabp->b_ioflags |= BIO_ERROR;
  663                                     vfs_unbusy_pages(rabp);
  664                                     brelse(rabp);
  665                                 }
  666                             } else {
  667                                 brelse(rabp);
  668                             }
  669                         }
  670                 }
  671                 /*
  672                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  673                  * chopped for the EOF condition, we cannot tell how large
  674                  * NFS directories are going to be until we hit EOF.  So
  675                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  676                  * it just so happens that b_resid will effectively chop it
  677                  * to EOF.  *BUT* this information is lost if the buffer goes
  678                  * away and is reconstituted into a B_CACHE state ( due to
  679                  * being VMIO ) later.  So we keep track of the directory eof
  680                  * in np->n_direofoffset and chop it off as an extra step
  681                  * right here.
  682                  */
  683                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  684                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  685                         n = np->n_direofoffset - uio->uio_offset;
  686                 break;
  687             default:
  688                 nfs_printf(" nfs_bioread: type %x unexpected\n", vp->v_type);
  689                 bp = NULL;
  690                 break;
  691             };
  692 
  693             if (n > 0) {
  694                     error = uiomove(bp->b_data + on, (int)n, uio);
  695             }
  696             if (vp->v_type == VLNK)
  697                 n = 0;
  698             if (bp != NULL)
  699                 brelse(bp);
  700         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  701         return (error);
  702 }
  703 
  704 /*
  705  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  706  * break up iovecs accordingly (restricting them to wsize).
  707  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  708  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  709  * user buffer to a staging buffer and then a second copy from the staging
  710  * buffer to mbufs. This can be optimized by copying from the user buffer
  711  * directly into mbufs and passing the chain down, but that requires a 
  712  * fair amount of re-working of the relevant codepaths (and can be done
  713  * later).
  714  */
  715 static int
  716 nfs_directio_write(vp, uiop, cred, ioflag)
  717         struct vnode *vp;
  718         struct uio *uiop;
  719         struct ucred *cred;
  720         int ioflag;
  721 {
  722         int error;
  723         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  724         struct thread *td = uiop->uio_td;
  725         int size;
  726         int wsize;
  727         
  728         mtx_lock(&nmp->nm_mtx);
  729         wsize = nmp->nm_wsize;
  730         mtx_unlock(&nmp->nm_mtx);
  731         if (ioflag & IO_SYNC) {
  732                 int iomode, must_commit;
  733                 struct uio uio;
  734                 struct iovec iov;
  735 do_sync:
  736                 while (uiop->uio_resid > 0) {
  737                         size = MIN(uiop->uio_resid, wsize);
  738                         size = MIN(uiop->uio_iov->iov_len, size);
  739                         iov.iov_base = uiop->uio_iov->iov_base;
  740                         iov.iov_len = size;
  741                         uio.uio_iov = &iov;
  742                         uio.uio_iovcnt = 1;
  743                         uio.uio_offset = uiop->uio_offset;
  744                         uio.uio_resid = size;
  745                         uio.uio_segflg = UIO_USERSPACE;
  746                         uio.uio_rw = UIO_WRITE;
  747                         uio.uio_td = td;
  748                         iomode = NFSV3WRITE_FILESYNC;
  749                         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, 
  750                                                       &iomode, &must_commit);
  751                         KASSERT((must_commit == 0), 
  752                                 ("nfs_directio_write: Did not commit write"));
  753                         if (error)
  754                                 return (error);
  755                         uiop->uio_offset += size;
  756                         uiop->uio_resid -= size;
  757                         if (uiop->uio_iov->iov_len <= size) {
  758                                 uiop->uio_iovcnt--;
  759                                 uiop->uio_iov++;
  760                         } else {
  761                                 uiop->uio_iov->iov_base = 
  762                                         (char *)uiop->uio_iov->iov_base + size;
  763                                 uiop->uio_iov->iov_len -= size;
  764                         }
  765                 }
  766         } else {
  767                 struct uio *t_uio;
  768                 struct iovec *t_iov;
  769                 struct buf *bp;
  770                 
  771                 /*
  772                  * Break up the write into blocksize chunks and hand these
  773                  * over to nfsiod's for write back.
  774                  * Unfortunately, this incurs a copy of the data. Since 
  775                  * the user could modify the buffer before the write is 
  776                  * initiated.
  777                  * 
  778                  * The obvious optimization here is that one of the 2 copies
  779                  * in the async write path can be eliminated by copying the
  780                  * data here directly into mbufs and passing the mbuf chain
  781                  * down. But that will require a fair amount of re-working
  782                  * of the code and can be done if there's enough interest
  783                  * in NFS directio access.
  784                  */
  785                 while (uiop->uio_resid > 0) {
  786                         size = MIN(uiop->uio_resid, wsize);
  787                         size = MIN(uiop->uio_iov->iov_len, size);
  788                         bp = getpbuf(&nfs_pbuf_freecnt);
  789                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  790                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  791                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  792                         t_iov->iov_len = size;
  793                         t_uio->uio_iov = t_iov;
  794                         t_uio->uio_iovcnt = 1;
  795                         t_uio->uio_offset = uiop->uio_offset;
  796                         t_uio->uio_resid = size;
  797                         t_uio->uio_segflg = UIO_SYSSPACE;
  798                         t_uio->uio_rw = UIO_WRITE;
  799                         t_uio->uio_td = td;
  800                         KASSERT(uiop->uio_segflg == UIO_USERSPACE ||
  801                             uiop->uio_segflg == UIO_SYSSPACE,
  802                             ("nfs_directio_write: Bad uio_segflg"));
  803                         if (uiop->uio_segflg == UIO_USERSPACE) {
  804                                 error = copyin(uiop->uio_iov->iov_base,
  805                                     t_iov->iov_base, size);
  806                                 if (error != 0)
  807                                         goto err_free;
  808                         } else
  809                                 /*
  810                                  * UIO_SYSSPACE may never happen, but handle
  811                                  * it just in case it does.
  812                                  */
  813                                 bcopy(uiop->uio_iov->iov_base, t_iov->iov_base,
  814                                     size);
  815                         bp->b_flags |= B_DIRECT;
  816                         bp->b_iocmd = BIO_WRITE;
  817                         if (cred != NOCRED) {
  818                                 crhold(cred);
  819                                 bp->b_wcred = cred;
  820                         } else 
  821                                 bp->b_wcred = NOCRED;                   
  822                         bp->b_caller1 = (void *)t_uio;
  823                         bp->b_vp = vp;
  824                         error = nfs_asyncio(nmp, bp, NOCRED, td);
  825 err_free:
  826                         if (error) {
  827                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  828                                 free(t_iov, M_NFSDIRECTIO);
  829                                 free(t_uio, M_NFSDIRECTIO);
  830                                 bp->b_vp = NULL;
  831                                 relpbuf(bp, &nfs_pbuf_freecnt);
  832                                 if (error == EINTR)
  833                                         return (error);
  834                                 goto do_sync;
  835                         }
  836                         uiop->uio_offset += size;
  837                         uiop->uio_resid -= size;
  838                         if (uiop->uio_iov->iov_len <= size) {
  839                                 uiop->uio_iovcnt--;
  840                                 uiop->uio_iov++;
  841                         } else {
  842                                 uiop->uio_iov->iov_base = 
  843                                         (char *)uiop->uio_iov->iov_base + size;
  844                                 uiop->uio_iov->iov_len -= size;
  845                         }
  846                 }
  847         }
  848         return (0);
  849 }
  850 
  851 /*
  852  * Vnode op for write using bio
  853  */
  854 int
  855 nfs_write(struct vop_write_args *ap)
  856 {
  857         int biosize;
  858         struct uio *uio = ap->a_uio;
  859         struct thread *td = uio->uio_td;
  860         struct vnode *vp = ap->a_vp;
  861         struct nfsnode *np = VTONFS(vp);
  862         struct ucred *cred = ap->a_cred;
  863         int ioflag = ap->a_ioflag;
  864         struct buf *bp;
  865         struct vattr vattr;
  866         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  867         daddr_t lbn;
  868         off_t end;
  869         int bcount;
  870         int n, on, error = 0;
  871 
  872         KASSERT(uio->uio_rw == UIO_WRITE, ("nfs_write mode"));
  873         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  874             ("nfs_write proc"));
  875         if (vp->v_type != VREG)
  876                 return (EIO);
  877         mtx_lock(&np->n_mtx);
  878         if (np->n_flag & NWRITEERR) {
  879                 np->n_flag &= ~NWRITEERR;
  880                 mtx_unlock(&np->n_mtx);
  881                 return (np->n_error);
  882         } else
  883                 mtx_unlock(&np->n_mtx);
  884         mtx_lock(&nmp->nm_mtx);
  885         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  886             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  887                 mtx_unlock(&nmp->nm_mtx);
  888                 (void)nfs_fsinfo(nmp, vp, cred, td);
  889         } else
  890                 mtx_unlock(&nmp->nm_mtx);
  891 
  892         /*
  893          * Synchronously flush pending buffers if we are in synchronous
  894          * mode or if we are appending.
  895          */
  896         if (ioflag & (IO_APPEND | IO_SYNC)) {
  897                 mtx_lock(&np->n_mtx);
  898                 if (np->n_flag & NMODIFIED) {
  899                         mtx_unlock(&np->n_mtx);
  900 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  901                         /*
  902                          * Require non-blocking, synchronous writes to
  903                          * dirty files to inform the program it needs
  904                          * to fsync(2) explicitly.
  905                          */
  906                         if (ioflag & IO_NDELAY)
  907                                 return (EAGAIN);
  908 #endif
  909 flush_and_restart:
  910                         np->n_attrstamp = 0;
  911                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  912                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  913                         if (error)
  914                                 return (error);
  915                 } else
  916                         mtx_unlock(&np->n_mtx);
  917         }
  918 
  919         /*
  920          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  921          * get the append lock.
  922          */
  923         if (ioflag & IO_APPEND) {
  924                 np->n_attrstamp = 0;
  925                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  926                 error = VOP_GETATTR(vp, &vattr, cred);
  927                 if (error)
  928                         return (error);
  929                 mtx_lock(&np->n_mtx);
  930                 uio->uio_offset = np->n_size;
  931                 mtx_unlock(&np->n_mtx);
  932         }
  933 
  934         if (uio->uio_offset < 0)
  935                 return (EINVAL);
  936         end = uio->uio_offset + uio->uio_resid;
  937         if (end > nmp->nm_maxfilesize || end < uio->uio_offset)
  938                 return (EFBIG);
  939         if (uio->uio_resid == 0)
  940                 return (0);
  941 
  942         if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  943                 return nfs_directio_write(vp, uio, cred, ioflag);
  944 
  945         /*
  946          * Maybe this should be above the vnode op call, but so long as
  947          * file servers have no limits, i don't think it matters
  948          */
  949         if (vn_rlimit_fsize(vp, uio, td))
  950                 return (EFBIG);
  951 
  952         biosize = vp->v_bufobj.bo_bsize;
  953         /*
  954          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  955          * would exceed the local maximum per-file write commit size when
  956          * combined with those, we must decide whether to flush,
  957          * go synchronous, or return error.  We don't bother checking
  958          * IO_UNIT -- we just make all writes atomic anyway, as there's
  959          * no point optimizing for something that really won't ever happen.
  960          */
  961         if (!(ioflag & IO_SYNC)) {
  962                 int nflag;
  963 
  964                 mtx_lock(&np->n_mtx);
  965                 nflag = np->n_flag;
  966                 mtx_unlock(&np->n_mtx);         
  967                 int needrestart = 0;
  968                 if (nmp->nm_wcommitsize < uio->uio_resid) {
  969                         /*
  970                          * If this request could not possibly be completed
  971                          * without exceeding the maximum outstanding write
  972                          * commit size, see if we can convert it into a
  973                          * synchronous write operation.
  974                          */
  975                         if (ioflag & IO_NDELAY)
  976                                 return (EAGAIN);
  977                         ioflag |= IO_SYNC;
  978                         if (nflag & NMODIFIED)
  979                                 needrestart = 1;
  980                 } else if (nflag & NMODIFIED) {
  981                         int wouldcommit = 0;
  982                         BO_LOCK(&vp->v_bufobj);
  983                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  984                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  985                                     b_bobufs) {
  986                                         if (bp->b_flags & B_NEEDCOMMIT)
  987                                                 wouldcommit += bp->b_bcount;
  988                                 }
  989                         }
  990                         BO_UNLOCK(&vp->v_bufobj);
  991                         /*
  992                          * Since we're not operating synchronously and
  993                          * bypassing the buffer cache, we are in a commit
  994                          * and holding all of these buffers whether
  995                          * transmitted or not.  If not limited, this
  996                          * will lead to the buffer cache deadlocking,
  997                          * as no one else can flush our uncommitted buffers.
  998                          */
  999                         wouldcommit += uio->uio_resid;
 1000                         /*
 1001                          * If we would initially exceed the maximum
 1002                          * outstanding write commit size, flush and restart.
 1003                          */
 1004                         if (wouldcommit > nmp->nm_wcommitsize)
 1005                                 needrestart = 1;
 1006                 }
 1007                 if (needrestart)
 1008                         goto flush_and_restart;
 1009         }
 1010 
 1011         do {
 1012                 nfsstats.biocache_writes++;
 1013                 lbn = uio->uio_offset / biosize;
 1014                 on = uio->uio_offset - (lbn * biosize);
 1015                 n = MIN((unsigned)(biosize - on), uio->uio_resid);
 1016 again:
 1017                 /*
 1018                  * Handle direct append and file extension cases, calculate
 1019                  * unaligned buffer size.
 1020                  */
 1021                 mtx_lock(&np->n_mtx);
 1022                 if (uio->uio_offset == np->n_size && n) {
 1023                         mtx_unlock(&np->n_mtx);
 1024                         /*
 1025                          * Get the buffer (in its pre-append state to maintain
 1026                          * B_CACHE if it was previously set).  Resize the
 1027                          * nfsnode after we have locked the buffer to prevent
 1028                          * readers from reading garbage.
 1029                          */
 1030                         bcount = on;
 1031                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1032 
 1033                         if (bp != NULL) {
 1034                                 long save;
 1035 
 1036                                 mtx_lock(&np->n_mtx);
 1037                                 np->n_size = uio->uio_offset + n;
 1038                                 np->n_flag |= NMODIFIED;
 1039                                 vnode_pager_setsize(vp, np->n_size);
 1040                                 mtx_unlock(&np->n_mtx);
 1041 
 1042                                 save = bp->b_flags & B_CACHE;
 1043                                 bcount += n;
 1044                                 allocbuf(bp, bcount);
 1045                                 bp->b_flags |= save;
 1046                         }
 1047                 } else {
 1048                         /*
 1049                          * Obtain the locked cache block first, and then
 1050                          * adjust the file's size as appropriate.
 1051                          */
 1052                         bcount = on + n;
 1053                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1054                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1055                                         bcount = biosize;
 1056                                 else
 1057                                         bcount = np->n_size - (off_t)lbn * biosize;
 1058                         }
 1059                         mtx_unlock(&np->n_mtx);
 1060                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1061                         mtx_lock(&np->n_mtx);
 1062                         if (uio->uio_offset + n > np->n_size) {
 1063                                 np->n_size = uio->uio_offset + n;
 1064                                 np->n_flag |= NMODIFIED;
 1065                                 vnode_pager_setsize(vp, np->n_size);
 1066                         }
 1067                         mtx_unlock(&np->n_mtx);
 1068                 }
 1069 
 1070                 if (!bp) {
 1071                         error = nfs_sigintr(nmp, td);
 1072                         if (!error)
 1073                                 error = EINTR;
 1074                         break;
 1075                 }
 1076 
 1077                 /*
 1078                  * Issue a READ if B_CACHE is not set.  In special-append
 1079                  * mode, B_CACHE is based on the buffer prior to the write
 1080                  * op and is typically set, avoiding the read.  If a read
 1081                  * is required in special append mode, the server will
 1082                  * probably send us a short-read since we extended the file
 1083                  * on our end, resulting in b_resid == 0 and, thusly,
 1084                  * B_CACHE getting set.
 1085                  *
 1086                  * We can also avoid issuing the read if the write covers
 1087                  * the entire buffer.  We have to make sure the buffer state
 1088                  * is reasonable in this case since we will not be initiating
 1089                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1090                  * more information.
 1091                  *
 1092                  * B_CACHE may also be set due to the buffer being cached
 1093                  * normally.
 1094                  */
 1095 
 1096                 if (on == 0 && n == bcount) {
 1097                         bp->b_flags |= B_CACHE;
 1098                         bp->b_flags &= ~B_INVAL;
 1099                         bp->b_ioflags &= ~BIO_ERROR;
 1100                 }
 1101 
 1102                 if ((bp->b_flags & B_CACHE) == 0) {
 1103                         bp->b_iocmd = BIO_READ;
 1104                         vfs_busy_pages(bp, 0);
 1105                         error = nfs_doio(vp, bp, cred, td);
 1106                         if (error) {
 1107                                 brelse(bp);
 1108                                 break;
 1109                         }
 1110                 }
 1111                 if (bp->b_wcred == NOCRED)
 1112                         bp->b_wcred = crhold(cred);
 1113                 mtx_lock(&np->n_mtx);
 1114                 np->n_flag |= NMODIFIED;
 1115                 mtx_unlock(&np->n_mtx);
 1116 
 1117                 /*
 1118                  * If dirtyend exceeds file size, chop it down.  This should
 1119                  * not normally occur but there is an append race where it
 1120                  * might occur XXX, so we log it.
 1121                  *
 1122                  * If the chopping creates a reverse-indexed or degenerate
 1123                  * situation with dirtyoff/end, we 0 both of them.
 1124                  */
 1125 
 1126                 if (bp->b_dirtyend > bcount) {
 1127                         nfs_printf("NFS append race @%lx:%d\n",
 1128                             (long)bp->b_blkno * DEV_BSIZE,
 1129                             bp->b_dirtyend - bcount);
 1130                         bp->b_dirtyend = bcount;
 1131                 }
 1132 
 1133                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1134                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1135 
 1136                 /*
 1137                  * If the new write will leave a contiguous dirty
 1138                  * area, just update the b_dirtyoff and b_dirtyend,
 1139                  * otherwise force a write rpc of the old dirty area.
 1140                  *
 1141                  * While it is possible to merge discontiguous writes due to
 1142                  * our having a B_CACHE buffer ( and thus valid read data
 1143                  * for the hole), we don't because it could lead to
 1144                  * significant cache coherency problems with multiple clients,
 1145                  * especially if locking is implemented later on.
 1146                  *
 1147                  * as an optimization we could theoretically maintain
 1148                  * a linked list of discontinuous areas, but we would still
 1149                  * have to commit them separately so there isn't much
 1150                  * advantage to it except perhaps a bit of asynchronization.
 1151                  */
 1152 
 1153                 if (bp->b_dirtyend > 0 &&
 1154                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1155                         if (bwrite(bp) == EINTR) {
 1156                                 error = EINTR;
 1157                                 break;
 1158                         }
 1159                         goto again;
 1160                 }
 1161 
 1162                 error = uiomove((char *)bp->b_data + on, n, uio);
 1163 
 1164                 /*
 1165                  * Since this block is being modified, it must be written
 1166                  * again and not just committed.  Since write clustering does
 1167                  * not work for the stage 1 data write, only the stage 2
 1168                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1169                  */
 1170                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1171 
 1172                 if (error) {
 1173                         bp->b_ioflags |= BIO_ERROR;
 1174                         brelse(bp);
 1175                         break;
 1176                 }
 1177 
 1178                 /*
 1179                  * Only update dirtyoff/dirtyend if not a degenerate
 1180                  * condition.
 1181                  */
 1182                 if (n) {
 1183                         if (bp->b_dirtyend > 0) {
 1184                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1185                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1186                         } else {
 1187                                 bp->b_dirtyoff = on;
 1188                                 bp->b_dirtyend = on + n;
 1189                         }
 1190                         vfs_bio_set_valid(bp, on, n);
 1191                 }
 1192 
 1193                 /*
 1194                  * If IO_SYNC do bwrite().
 1195                  *
 1196                  * IO_INVAL appears to be unused.  The idea appears to be
 1197                  * to turn off caching in this case.  Very odd.  XXX
 1198                  */
 1199                 if ((ioflag & IO_SYNC)) {
 1200                         if (ioflag & IO_INVAL)
 1201                                 bp->b_flags |= B_NOCACHE;
 1202                         error = bwrite(bp);
 1203                         if (error)
 1204                                 break;
 1205                 } else if ((n + on) == biosize) {
 1206                         bp->b_flags |= B_ASYNC;
 1207                         (void) (nmp->nm_rpcops->nr_writebp)(bp, 0, NULL);
 1208                 } else {
 1209                         bdwrite(bp);
 1210                 }
 1211         } while (uio->uio_resid > 0 && n > 0);
 1212 
 1213         return (error);
 1214 }
 1215 
 1216 /*
 1217  * Get an nfs cache block.
 1218  *
 1219  * Allocate a new one if the block isn't currently in the cache
 1220  * and return the block marked busy. If the calling process is
 1221  * interrupted by a signal for an interruptible mount point, return
 1222  * NULL.
 1223  *
 1224  * The caller must carefully deal with the possible B_INVAL state of
 1225  * the buffer.  nfs_doio() clears B_INVAL (and nfs_asyncio() clears it
 1226  * indirectly), so synchronous reads can be issued without worrying about
 1227  * the B_INVAL state.  We have to be a little more careful when dealing
 1228  * with writes (see comments in nfs_write()) when extending a file past
 1229  * its EOF.
 1230  */
 1231 static struct buf *
 1232 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1233 {
 1234         struct buf *bp;
 1235         struct mount *mp;
 1236         struct nfsmount *nmp;
 1237 
 1238         mp = vp->v_mount;
 1239         nmp = VFSTONFS(mp);
 1240 
 1241         if (nmp->nm_flag & NFSMNT_INT) {
 1242                 sigset_t oldset;
 1243 
 1244                 nfs_set_sigmask(td, &oldset);
 1245                 bp = getblk(vp, bn, size, PCATCH, 0, 0);
 1246                 nfs_restore_sigmask(td, &oldset);
 1247                 while (bp == NULL) {
 1248                         if (nfs_sigintr(nmp, td))
 1249                                 return (NULL);
 1250                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1251                 }
 1252         } else {
 1253                 bp = getblk(vp, bn, size, 0, 0, 0);
 1254         }
 1255 
 1256         if (vp->v_type == VREG)
 1257                 bp->b_blkno = bn * (vp->v_bufobj.bo_bsize / DEV_BSIZE);
 1258         return (bp);
 1259 }
 1260 
 1261 /*
 1262  * Flush and invalidate all dirty buffers. If another process is already
 1263  * doing the flush, just wait for completion.
 1264  */
 1265 int
 1266 nfs_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1267 {
 1268         struct nfsnode *np = VTONFS(vp);
 1269         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1270         int error = 0, slpflag, slptimeo;
 1271         int old_lock = 0;
 1272 
 1273         ASSERT_VOP_LOCKED(vp, "nfs_vinvalbuf");
 1274 
 1275         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1276                 intrflg = 0;
 1277         if (intrflg) {
 1278                 slpflag = PCATCH;
 1279                 slptimeo = 2 * hz;
 1280         } else {
 1281                 slpflag = 0;
 1282                 slptimeo = 0;
 1283         }
 1284 
 1285         old_lock = nfs_upgrade_vnlock(vp);
 1286         if (vp->v_iflag & VI_DOOMED) {
 1287                 /*
 1288                  * Since vgonel() uses the generic vinvalbuf() to flush
 1289                  * dirty buffers and it does not call this function, it
 1290                  * is safe to just return OK when VI_DOOMED is set.
 1291                  */
 1292                 nfs_downgrade_vnlock(vp, old_lock);
 1293                 return (0);
 1294         }
 1295 
 1296         /*
 1297          * Now, flush as required.
 1298          */
 1299         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1300                 VM_OBJECT_WLOCK(vp->v_bufobj.bo_object);
 1301                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1302                 VM_OBJECT_WUNLOCK(vp->v_bufobj.bo_object);
 1303                 /*
 1304                  * If the page clean was interrupted, fail the invalidation.
 1305                  * Not doing so, we run the risk of losing dirty pages in the 
 1306                  * vinvalbuf() call below.
 1307                  */
 1308                 if (intrflg && (error = nfs_sigintr(nmp, td)))
 1309                         goto out;
 1310         }
 1311 
 1312         error = vinvalbuf(vp, flags, slpflag, 0);
 1313         while (error) {
 1314                 if (intrflg && (error = nfs_sigintr(nmp, td)))
 1315                         goto out;
 1316                 error = vinvalbuf(vp, flags, 0, slptimeo);
 1317         }
 1318         mtx_lock(&np->n_mtx);
 1319         if (np->n_directio_asyncwr == 0)
 1320                 np->n_flag &= ~NMODIFIED;
 1321         mtx_unlock(&np->n_mtx);
 1322 out:
 1323         nfs_downgrade_vnlock(vp, old_lock);
 1324         return error;
 1325 }
 1326 
 1327 /*
 1328  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1329  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1330  * are all hung on a dead server.
 1331  *
 1332  * Note: nfs_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1333  * is eventually dequeued by the async daemon, nfs_doio() *will*.
 1334  */
 1335 int
 1336 nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1337 {
 1338         int iod;
 1339         int gotiod;
 1340         int slpflag = 0;
 1341         int slptimeo = 0;
 1342         int error, error2;
 1343 
 1344         /*
 1345          * Commits are usually short and sweet so lets save some cpu and
 1346          * leave the async daemons for more important rpc's (such as reads
 1347          * and writes).
 1348          *
 1349          * Readdirplus RPCs do vget()s to acquire the vnodes for entries
 1350          * in the directory in order to update attributes. This can deadlock
 1351          * with another thread that is waiting for async I/O to be done by
 1352          * an nfsiod thread while holding a lock on one of these vnodes.
 1353          * To avoid this deadlock, don't allow the async nfsiod threads to
 1354          * perform Readdirplus RPCs.
 1355          */
 1356         mtx_lock(&nfs_iod_mtx);
 1357         if ((bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1358              (nmp->nm_bufqiods > nfs_numasync / 2)) ||
 1359             (bp->b_vp->v_type == VDIR && (nmp->nm_flag & NFSMNT_RDIRPLUS))) {
 1360                 mtx_unlock(&nfs_iod_mtx);
 1361                 return(EIO);
 1362         }
 1363 again:
 1364         if (nmp->nm_flag & NFSMNT_INT)
 1365                 slpflag = PCATCH;
 1366         gotiod = FALSE;
 1367 
 1368         /*
 1369          * Find a free iod to process this request.
 1370          */
 1371         for (iod = 0; iod < nfs_numasync; iod++)
 1372                 if (nfs_iodwant[iod] == NFSIOD_AVAILABLE) {
 1373                         gotiod = TRUE;
 1374                         break;
 1375                 }
 1376 
 1377         /*
 1378          * Try to create one if none are free.
 1379          */
 1380         if (!gotiod)
 1381                 nfs_nfsiodnew();
 1382         else {
 1383                 /*
 1384                  * Found one, so wake it up and tell it which
 1385                  * mount to process.
 1386                  */
 1387                 NFS_DPF(ASYNCIO, ("nfs_asyncio: waking iod %d for mount %p\n",
 1388                     iod, nmp));
 1389                 nfs_iodwant[iod] = NFSIOD_NOT_AVAILABLE;
 1390                 nfs_iodmount[iod] = nmp;
 1391                 nmp->nm_bufqiods++;
 1392                 wakeup(&nfs_iodwant[iod]);
 1393         }
 1394 
 1395         /*
 1396          * If none are free, we may already have an iod working on this mount
 1397          * point.  If so, it will process our request.
 1398          */
 1399         if (!gotiod) {
 1400                 if (nmp->nm_bufqiods > 0) {
 1401                         NFS_DPF(ASYNCIO,
 1402                 ("nfs_asyncio: %d iods are already processing mount %p\n",
 1403                                  nmp->nm_bufqiods, nmp));
 1404                         gotiod = TRUE;
 1405                 }
 1406         }
 1407 
 1408         /*
 1409          * If we have an iod which can process the request, then queue
 1410          * the buffer.
 1411          */
 1412         if (gotiod) {
 1413                 /*
 1414                  * Ensure that the queue never grows too large.  We still want
 1415                  * to asynchronize so we block rather then return EIO.
 1416                  */
 1417                 while (nmp->nm_bufqlen >= 2 * nfs_numasync) {
 1418                         NFS_DPF(ASYNCIO,
 1419                 ("nfs_asyncio: waiting for mount %p queue to drain\n", nmp));
 1420                         nmp->nm_bufqwant = TRUE;
 1421                         error = nfs_msleep(td, &nmp->nm_bufq, &nfs_iod_mtx, 
 1422                                            slpflag | PRIBIO,
 1423                                            "nfsaio", slptimeo);
 1424                         if (error) {
 1425                                 error2 = nfs_sigintr(nmp, td);
 1426                                 if (error2) {
 1427                                         mtx_unlock(&nfs_iod_mtx);
 1428                                         return (error2);
 1429                                 }
 1430                                 if (slpflag == PCATCH) {
 1431                                         slpflag = 0;
 1432                                         slptimeo = 2 * hz;
 1433                                 }
 1434                         }
 1435                         /*
 1436                          * We might have lost our iod while sleeping,
 1437                          * so check and loop if nescessary.
 1438                          */
 1439                         goto again;
 1440                 }
 1441 
 1442                 /* We might have lost our nfsiod */
 1443                 if (nmp->nm_bufqiods == 0) {
 1444                         NFS_DPF(ASYNCIO,
 1445 ("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1446                         goto again;
 1447                 }
 1448 
 1449                 if (bp->b_iocmd == BIO_READ) {
 1450                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1451                                 bp->b_rcred = crhold(cred);
 1452                 } else {
 1453                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1454                                 bp->b_wcred = crhold(cred);
 1455                 }
 1456 
 1457                 if (bp->b_flags & B_REMFREE)
 1458                         bremfreef(bp);
 1459                 BUF_KERNPROC(bp);
 1460                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1461                 nmp->nm_bufqlen++;
 1462                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1463                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);                   
 1464                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1465                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1466                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1467                 }
 1468                 mtx_unlock(&nfs_iod_mtx);
 1469                 return (0);
 1470         }
 1471 
 1472         mtx_unlock(&nfs_iod_mtx);
 1473 
 1474         /*
 1475          * All the iods are busy on other mounts, so return EIO to
 1476          * force the caller to process the i/o synchronously.
 1477          */
 1478         NFS_DPF(ASYNCIO, ("nfs_asyncio: no iods available, i/o is synchronous\n"));
 1479         return (EIO);
 1480 }
 1481 
 1482 void
 1483 nfs_doio_directwrite(struct buf *bp)
 1484 {
 1485         int iomode, must_commit;
 1486         struct uio *uiop = (struct uio *)bp->b_caller1;
 1487         char *iov_base = uiop->uio_iov->iov_base;
 1488         struct nfsmount *nmp = VFSTONFS(bp->b_vp->v_mount);
 1489         
 1490         iomode = NFSV3WRITE_FILESYNC;
 1491         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1492         (nmp->nm_rpcops->nr_writerpc)(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
 1493         KASSERT((must_commit == 0), ("nfs_doio_directwrite: Did not commit write"));
 1494         free(iov_base, M_NFSDIRECTIO);
 1495         free(uiop->uio_iov, M_NFSDIRECTIO);
 1496         free(uiop, M_NFSDIRECTIO);
 1497         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1498                 struct nfsnode *np = VTONFS(bp->b_vp);
 1499                 mtx_lock(&np->n_mtx);
 1500                 np->n_directio_asyncwr--;
 1501                 if (np->n_directio_asyncwr == 0) {
 1502                         VTONFS(bp->b_vp)->n_flag &= ~NMODIFIED;
 1503                         if ((np->n_flag & NFSYNCWAIT)) {
 1504                                 np->n_flag &= ~NFSYNCWAIT;
 1505                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1506                         }
 1507                 }
 1508                 mtx_unlock(&np->n_mtx);
 1509         }
 1510         bp->b_vp = NULL;
 1511         relpbuf(bp, &nfs_pbuf_freecnt);
 1512 }
 1513 
 1514 /*
 1515  * Do an I/O operation to/from a cache block. This may be called
 1516  * synchronously or from an nfsiod.
 1517  */
 1518 int
 1519 nfs_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
 1520 {
 1521         struct uio *uiop;
 1522         struct nfsnode *np;
 1523         struct nfsmount *nmp;
 1524         int error = 0, iomode, must_commit = 0;
 1525         struct uio uio;
 1526         struct iovec io;
 1527         struct proc *p = td ? td->td_proc : NULL;
 1528         uint8_t iocmd;
 1529         
 1530         np = VTONFS(vp);
 1531         nmp = VFSTONFS(vp->v_mount);
 1532         uiop = &uio;
 1533         uiop->uio_iov = &io;
 1534         uiop->uio_iovcnt = 1;
 1535         uiop->uio_segflg = UIO_SYSSPACE;
 1536         uiop->uio_td = td;
 1537 
 1538         /*
 1539          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1540          * do this here so we do not have to do it in all the code that
 1541          * calls us.
 1542          */
 1543         bp->b_flags &= ~B_INVAL;
 1544         bp->b_ioflags &= ~BIO_ERROR;
 1545 
 1546         KASSERT(!(bp->b_flags & B_DONE), ("nfs_doio: bp %p already marked done", bp));
 1547         iocmd = bp->b_iocmd;
 1548         if (iocmd == BIO_READ) {
 1549             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1550             io.iov_base = bp->b_data;
 1551             uiop->uio_rw = UIO_READ;
 1552 
 1553             switch (vp->v_type) {
 1554             case VREG:
 1555                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1556                 nfsstats.read_bios++;
 1557                 error = (nmp->nm_rpcops->nr_readrpc)(vp, uiop, cr);
 1558 
 1559                 if (!error) {
 1560                     if (uiop->uio_resid) {
 1561                         /*
 1562                          * If we had a short read with no error, we must have
 1563                          * hit a file hole.  We should zero-fill the remainder.
 1564                          * This can also occur if the server hits the file EOF.
 1565                          *
 1566                          * Holes used to be able to occur due to pending
 1567                          * writes, but that is not possible any longer.
 1568                          */
 1569                         int nread = bp->b_bcount - uiop->uio_resid;
 1570                         int left  = uiop->uio_resid;
 1571 
 1572                         if (left > 0)
 1573                                 bzero((char *)bp->b_data + nread, left);
 1574                         uiop->uio_resid = 0;
 1575                     }
 1576                 }
 1577                 /* ASSERT_VOP_LOCKED(vp, "nfs_doio"); */
 1578                 if (p && (vp->v_vflag & VV_TEXT)) {
 1579                         mtx_lock(&np->n_mtx);
 1580                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.va_mtime)) {
 1581                                 mtx_unlock(&np->n_mtx);
 1582                                 PROC_LOCK(p);
 1583                                 killproc(p, "text file modification");
 1584                                 PROC_UNLOCK(p);
 1585                         } else
 1586                                 mtx_unlock(&np->n_mtx);
 1587                 }
 1588                 break;
 1589             case VLNK:
 1590                 uiop->uio_offset = (off_t)0;
 1591                 nfsstats.readlink_bios++;
 1592                 error = (nmp->nm_rpcops->nr_readlinkrpc)(vp, uiop, cr);
 1593                 break;
 1594             case VDIR:
 1595                 nfsstats.readdir_bios++;
 1596                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1597                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1598                         error = nfs_readdirplusrpc(vp, uiop, cr);
 1599                         if (error == NFSERR_NOTSUPP)
 1600                                 nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1601                 }
 1602                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1603                         error = nfs_readdirrpc(vp, uiop, cr);
 1604                 /*
 1605                  * end-of-directory sets B_INVAL but does not generate an
 1606                  * error.
 1607                  */
 1608                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1609                         bp->b_flags |= B_INVAL;
 1610                 break;
 1611             default:
 1612                 nfs_printf("nfs_doio:  type %x unexpected\n", vp->v_type);
 1613                 break;
 1614             };
 1615             if (error) {
 1616                 bp->b_ioflags |= BIO_ERROR;
 1617                 bp->b_error = error;
 1618             }
 1619         } else {
 1620             /*
 1621              * If we only need to commit, try to commit
 1622              */
 1623             if (bp->b_flags & B_NEEDCOMMIT) {
 1624                     int retv;
 1625                     off_t off;
 1626 
 1627                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1628                     retv = (nmp->nm_rpcops->nr_commit)(
 1629                                 vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1630                                 bp->b_wcred, td);
 1631                     if (retv == 0) {
 1632                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1633                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1634                             bp->b_resid = 0;
 1635                             bufdone(bp);
 1636                             return (0);
 1637                     }
 1638                     if (retv == NFSERR_STALEWRITEVERF) {
 1639                             nfs_clearcommit(vp->v_mount);
 1640                     }
 1641             }
 1642 
 1643             /*
 1644              * Setup for actual write
 1645              */
 1646             mtx_lock(&np->n_mtx);
 1647             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1648                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1649             mtx_unlock(&np->n_mtx);
 1650 
 1651             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1652                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1653                     - bp->b_dirtyoff;
 1654                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1655                     + bp->b_dirtyoff;
 1656                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1657                 uiop->uio_rw = UIO_WRITE;
 1658                 nfsstats.write_bios++;
 1659 
 1660                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1661                     iomode = NFSV3WRITE_UNSTABLE;
 1662                 else
 1663                     iomode = NFSV3WRITE_FILESYNC;
 1664 
 1665                 error = (nmp->nm_rpcops->nr_writerpc)(vp, uiop, cr, &iomode, &must_commit);
 1666 
 1667                 /*
 1668                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1669                  * to cluster the buffers needing commit.  This will allow
 1670                  * the system to submit a single commit rpc for the whole
 1671                  * cluster.  We can do this even if the buffer is not 100%
 1672                  * dirty (relative to the NFS blocksize), so we optimize the
 1673                  * append-to-file-case.
 1674                  *
 1675                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1676                  * cleared because write clustering only works for commit
 1677                  * rpc's, not for the data portion of the write).
 1678                  */
 1679 
 1680                 if (!error && iomode == NFSV3WRITE_UNSTABLE) {
 1681                     bp->b_flags |= B_NEEDCOMMIT;
 1682                     if (bp->b_dirtyoff == 0
 1683                         && bp->b_dirtyend == bp->b_bcount)
 1684                         bp->b_flags |= B_CLUSTEROK;
 1685                 } else {
 1686                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1687                 }
 1688 
 1689                 /*
 1690                  * For an interrupted write, the buffer is still valid
 1691                  * and the write hasn't been pushed to the server yet,
 1692                  * so we can't set BIO_ERROR and report the interruption
 1693                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1694                  * is not relevant, so the rpc attempt is essentially
 1695                  * a noop.  For the case of a V3 write rpc not being
 1696                  * committed to stable storage, the block is still
 1697                  * dirty and requires either a commit rpc or another
 1698                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1699                  * the block is reused. This is indicated by setting
 1700                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1701                  *
 1702                  * If the buffer is marked B_PAGING, it does not reside on
 1703                  * the vp's paging queues so we cannot call bdirty().  The
 1704                  * bp in this case is not an NFS cache block so we should
 1705                  * be safe. XXX
 1706                  *
 1707                  * The logic below breaks up errors into recoverable and 
 1708                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1709                  * and keep the buffer around for potential write retries.
 1710                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1711                  * and save the error in the nfsnode. This is less than ideal 
 1712                  * but necessary. Keeping such buffers around could potentially
 1713                  * cause buffer exhaustion eventually (they can never be written
 1714                  * out, so will get constantly be re-dirtied). It also causes
 1715                  * all sorts of vfs panics. For non-recoverable write errors, 
 1716                  * also invalidate the attrcache, so we'll be forced to go over
 1717                  * the wire for this object, returning an error to user on next
 1718                  * call (most of the time).
 1719                  */
 1720                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1721                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1722                         int s;
 1723 
 1724                         s = splbio();
 1725                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1726                         if ((bp->b_flags & B_PAGING) == 0) {
 1727                             bdirty(bp);
 1728                             bp->b_flags &= ~B_DONE;
 1729                         }
 1730                         if (error && (bp->b_flags & B_ASYNC) == 0)
 1731                             bp->b_flags |= B_EINTR;
 1732                         splx(s);
 1733                 } else {
 1734                     if (error) {
 1735                         bp->b_ioflags |= BIO_ERROR;
 1736                         bp->b_flags |= B_INVAL;
 1737                         bp->b_error = np->n_error = error;
 1738                         mtx_lock(&np->n_mtx);
 1739                         np->n_flag |= NWRITEERR;
 1740                         np->n_attrstamp = 0;
 1741                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 1742                         mtx_unlock(&np->n_mtx);
 1743                     }
 1744                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1745                 }
 1746             } else {
 1747                 bp->b_resid = 0;
 1748                 bufdone(bp);
 1749                 return (0);
 1750             }
 1751         }
 1752         bp->b_resid = uiop->uio_resid;
 1753         if (must_commit)
 1754             nfs_clearcommit(vp->v_mount);
 1755         bufdone(bp);
 1756         return (error);
 1757 }
 1758 
 1759 /*
 1760  * Used to aid in handling ftruncate() operations on the NFS client side.
 1761  * Truncation creates a number of special problems for NFS.  We have to
 1762  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1763  * we have to properly handle VM pages or (potentially dirty) buffers
 1764  * that straddle the truncation point.
 1765  */
 1766 
 1767 int
 1768 nfs_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1769 {
 1770         struct nfsnode *np = VTONFS(vp);
 1771         u_quad_t tsize;
 1772         int biosize = vp->v_bufobj.bo_bsize;
 1773         int error = 0;
 1774 
 1775         mtx_lock(&np->n_mtx);
 1776         tsize = np->n_size;
 1777         np->n_size = nsize;
 1778         mtx_unlock(&np->n_mtx);
 1779 
 1780         if (nsize < tsize) {
 1781                 struct buf *bp;
 1782                 daddr_t lbn;
 1783                 int bufsize;
 1784 
 1785                 /*
 1786                  * vtruncbuf() doesn't get the buffer overlapping the 
 1787                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1788                  * buffer that now needs to be truncated.
 1789                  */
 1790                 error = vtruncbuf(vp, cred, nsize, biosize);
 1791                 lbn = nsize / biosize;
 1792                 bufsize = nsize - (lbn * biosize);
 1793                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1794                 if (!bp)
 1795                         return EINTR;
 1796                 if (bp->b_dirtyoff > bp->b_bcount)
 1797                         bp->b_dirtyoff = bp->b_bcount;
 1798                 if (bp->b_dirtyend > bp->b_bcount)
 1799                         bp->b_dirtyend = bp->b_bcount;
 1800                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1801                 brelse(bp);
 1802         } else {
 1803                 vnode_pager_setsize(vp, nsize);
 1804         }
 1805         return(error);
 1806 }
 1807 

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