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

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