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freebsd-dev/sys/nfsclient/nfs_bio.c
Rick Macklem 175b3f31d3 Both NFS clients can deadlock when using the "rdirplus" mount 
option. This can occur when an nfsiod thread that already holds
a buffer lock attempts to acquire a vnode lock on an entry in
the directory (a LOR) when another thread holding the vnode lock
is waiting on an nfsiod thread. This patch avoids the deadlock by disabling
readahead for this case, so the nfsiod threads never do readdirplus.
Since readaheads for directories need the directory offset cookie
from the previous read, they cannot normally happen in parallel.
As such, testing by jhb@ and myself didn't find any performance
degredation when this patch is applied. If there is a case where
this results in a significant performance degradation, mounting
without the "rdirplus" option can be done to re-enable readahead
for directories.

Reported and tested by:	jhb
Reviewed by:	jhb
MFC after:	2 weeks
2013-04-18 13:09:04 +00:00

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/*-
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Rick Macklem at The University of Guelph.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)nfs_bio.c 8.9 (Berkeley) 3/30/95
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_kdtrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
#include <sys/vmmeter.h>
#include <sys/vnode.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_extern.h>
#include <vm/vm_page.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>
#include <vm/vnode_pager.h>
#include <nfs/nfsproto.h>
#include <nfsclient/nfs.h>
#include <nfsclient/nfsmount.h>
#include <nfsclient/nfsnode.h>
#include <nfs/nfs_kdtrace.h>
static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
struct thread *td);
static int nfs_directio_write(struct vnode *vp, struct uio *uiop,
struct ucred *cred, int ioflag);
extern int nfs_directio_enable;
extern int nfs_directio_allow_mmap;
/*
* Vnode op for VM getpages.
*/
int
nfs_getpages(struct vop_getpages_args *ap)
{
int i, error, nextoff, size, toff, count, npages;
struct uio uio;
struct iovec iov;
vm_offset_t kva;
struct buf *bp;
struct vnode *vp;
struct thread *td;
struct ucred *cred;
struct nfsmount *nmp;
vm_object_t object;
vm_page_t *pages;
struct nfsnode *np;
vp = ap->a_vp;
np = VTONFS(vp);
td = curthread; /* XXX */
cred = curthread->td_ucred; /* XXX */
nmp = VFSTONFS(vp->v_mount);
pages = ap->a_m;
count = ap->a_count;
if ((object = vp->v_object) == NULL) {
nfs_printf("nfs_getpages: called with non-merged cache vnode??\n");
return (VM_PAGER_ERROR);
}
if (nfs_directio_enable && !nfs_directio_allow_mmap) {
mtx_lock(&np->n_mtx);
if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
mtx_unlock(&np->n_mtx);
nfs_printf("nfs_getpages: called on non-cacheable vnode??\n");
return (VM_PAGER_ERROR);
} else
mtx_unlock(&np->n_mtx);
}
mtx_lock(&nmp->nm_mtx);
if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
(nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
mtx_unlock(&nmp->nm_mtx);
/* We'll never get here for v4, because we always have fsinfo */
(void)nfs_fsinfo(nmp, vp, cred, td);
} else
mtx_unlock(&nmp->nm_mtx);
npages = btoc(count);
/*
* If the requested page is partially valid, just return it and
* allow the pager to zero-out the blanks. Partially valid pages
* can only occur at the file EOF.
*/
VM_OBJECT_WLOCK(object);
if (pages[ap->a_reqpage]->valid != 0) {
for (i = 0; i < npages; ++i) {
if (i != ap->a_reqpage) {
vm_page_lock(pages[i]);
vm_page_free(pages[i]);
vm_page_unlock(pages[i]);
}
}
VM_OBJECT_WUNLOCK(object);
return (0);
}
VM_OBJECT_WUNLOCK(object);
/*
* We use only the kva address for the buffer, but this is extremely
* convienient and fast.
*/
bp = getpbuf(&nfs_pbuf_freecnt);
kva = (vm_offset_t) bp->b_data;
pmap_qenter(kva, pages, npages);
PCPU_INC(cnt.v_vnodein);
PCPU_ADD(cnt.v_vnodepgsin, npages);
iov.iov_base = (caddr_t) kva;
iov.iov_len = count;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
uio.uio_resid = count;
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_rw = UIO_READ;
uio.uio_td = td;
error = (nmp->nm_rpcops->nr_readrpc)(vp, &uio, cred);
pmap_qremove(kva, npages);
relpbuf(bp, &nfs_pbuf_freecnt);
if (error && (uio.uio_resid == count)) {
nfs_printf("nfs_getpages: error %d\n", error);
VM_OBJECT_WLOCK(object);
for (i = 0; i < npages; ++i) {
if (i != ap->a_reqpage) {
vm_page_lock(pages[i]);
vm_page_free(pages[i]);
vm_page_unlock(pages[i]);
}
}
VM_OBJECT_WUNLOCK(object);
return (VM_PAGER_ERROR);
}
/*
* Calculate the number of bytes read and validate only that number
* of bytes. Note that due to pending writes, size may be 0. This
* does not mean that the remaining data is invalid!
*/
size = count - uio.uio_resid;
VM_OBJECT_WLOCK(object);
for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
vm_page_t m;
nextoff = toff + PAGE_SIZE;
m = pages[i];
if (nextoff <= size) {
/*
* Read operation filled an entire page
*/
m->valid = VM_PAGE_BITS_ALL;
KASSERT(m->dirty == 0,
("nfs_getpages: page %p is dirty", m));
} else if (size > toff) {
/*
* Read operation filled a partial page.
*/
m->valid = 0;
vm_page_set_valid_range(m, 0, size - toff);
KASSERT(m->dirty == 0,
("nfs_getpages: page %p is dirty", m));
} else {
/*
* Read operation was short. If no error
* occured we may have hit a zero-fill
* section. We leave valid set to 0, and page
* is freed by vm_page_readahead_finish() if
* its index is not equal to requested, or
* page is zeroed and set valid by
* vm_pager_get_pages() for requested page.
*/
;
}
if (i != ap->a_reqpage)
vm_page_readahead_finish(m);
}
VM_OBJECT_WUNLOCK(object);
return (0);
}
/*
* Vnode op for VM putpages.
*/
int
nfs_putpages(struct vop_putpages_args *ap)
{
struct uio uio;
struct iovec iov;
vm_offset_t kva;
struct buf *bp;
int iomode, must_commit, i, error, npages, count;
off_t offset;
int *rtvals;
struct vnode *vp;
struct thread *td;
struct ucred *cred;
struct nfsmount *nmp;
struct nfsnode *np;
vm_page_t *pages;
vp = ap->a_vp;
np = VTONFS(vp);
td = curthread; /* XXX */
/* Set the cred to n_writecred for the write rpcs. */
if (np->n_writecred != NULL)
cred = crhold(np->n_writecred);
else
cred = crhold(curthread->td_ucred); /* XXX */
nmp = VFSTONFS(vp->v_mount);
pages = ap->a_m;
count = ap->a_count;
rtvals = ap->a_rtvals;
npages = btoc(count);
offset = IDX_TO_OFF(pages[0]->pindex);
mtx_lock(&nmp->nm_mtx);
if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
(nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
mtx_unlock(&nmp->nm_mtx);
(void)nfs_fsinfo(nmp, vp, cred, td);
} else
mtx_unlock(&nmp->nm_mtx);
mtx_lock(&np->n_mtx);
if (nfs_directio_enable && !nfs_directio_allow_mmap &&
(np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
mtx_unlock(&np->n_mtx);
nfs_printf("nfs_putpages: called on noncache-able vnode??\n");
mtx_lock(&np->n_mtx);
}
for (i = 0; i < npages; i++)
rtvals[i] = VM_PAGER_ERROR;
/*
* When putting pages, do not extend file past EOF.
*/
if (offset + count > np->n_size) {
count = np->n_size - offset;
if (count < 0)
count = 0;
}
mtx_unlock(&np->n_mtx);
/*
* We use only the kva address for the buffer, but this is extremely
* convienient and fast.
*/
bp = getpbuf(&nfs_pbuf_freecnt);
kva = (vm_offset_t) bp->b_data;
pmap_qenter(kva, pages, npages);
PCPU_INC(cnt.v_vnodeout);
PCPU_ADD(cnt.v_vnodepgsout, count);
iov.iov_base = (caddr_t) kva;
iov.iov_len = count;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = offset;
uio.uio_resid = count;
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_rw = UIO_WRITE;
uio.uio_td = td;
if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
iomode = NFSV3WRITE_UNSTABLE;
else
iomode = NFSV3WRITE_FILESYNC;
error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, &iomode, &must_commit);
crfree(cred);
pmap_qremove(kva, npages);
relpbuf(bp, &nfs_pbuf_freecnt);
if (!error) {
vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
if (must_commit) {
nfs_clearcommit(vp->v_mount);
}
}
return rtvals[0];
}
/*
* For nfs, cache consistency can only be maintained approximately.
* Although RFC1094 does not specify the criteria, the following is
* believed to be compatible with the reference port.
* For nfs:
* If the file's modify time on the server has changed since the
* last read rpc or you have written to the file,
* you may have lost data cache consistency with the
* server, so flush all of the file's data out of the cache.
* Then force a getattr rpc to ensure that you have up to date
* attributes.
* NB: This implies that cache data can be read when up to
* NFS_ATTRTIMEO seconds out of date. If you find that you need current
* attributes this could be forced by setting n_attrstamp to 0 before
* the VOP_GETATTR() call.
*/
static inline int
nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
{
int error = 0;
struct vattr vattr;
struct nfsnode *np = VTONFS(vp);
int old_lock;
struct nfsmount *nmp = VFSTONFS(vp->v_mount);
/*
* Grab the exclusive lock before checking whether the cache is
* consistent.
* XXX - We can make this cheaper later (by acquiring cheaper locks).
* But for now, this suffices.
*/
old_lock = nfs_upgrade_vnlock(vp);
if (vp->v_iflag & VI_DOOMED) {
nfs_downgrade_vnlock(vp, old_lock);
return (EBADF);
}
mtx_lock(&np->n_mtx);
if (np->n_flag & NMODIFIED) {
mtx_unlock(&np->n_mtx);
if (vp->v_type != VREG) {
if (vp->v_type != VDIR)
panic("nfs: bioread, not dir");
(nmp->nm_rpcops->nr_invaldir)(vp);
error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
if (error)
goto out;
}
np->n_attrstamp = 0;
KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
error = VOP_GETATTR(vp, &vattr, cred);
if (error)
goto out;
mtx_lock(&np->n_mtx);
np->n_mtime = vattr.va_mtime;
mtx_unlock(&np->n_mtx);
} else {
mtx_unlock(&np->n_mtx);
error = VOP_GETATTR(vp, &vattr, cred);
if (error)
return (error);
mtx_lock(&np->n_mtx);
if ((np->n_flag & NSIZECHANGED)
|| (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
mtx_unlock(&np->n_mtx);
if (vp->v_type == VDIR)
(nmp->nm_rpcops->nr_invaldir)(vp);
error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
if (error)
goto out;
mtx_lock(&np->n_mtx);
np->n_mtime = vattr.va_mtime;
np->n_flag &= ~NSIZECHANGED;
}
mtx_unlock(&np->n_mtx);
}
out:
nfs_downgrade_vnlock(vp, old_lock);
return error;
}
/*
* Vnode op for read using bio
*/
int
nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
{
struct nfsnode *np = VTONFS(vp);
int biosize, i;
struct buf *bp, *rabp;
struct thread *td;
struct nfsmount *nmp = VFSTONFS(vp->v_mount);
daddr_t lbn, rabn;
off_t end;
int bcount;
int seqcount;
int nra, error = 0, n = 0, on = 0;
KASSERT(uio->uio_rw == UIO_READ, ("nfs_read mode"));
if (uio->uio_resid == 0)
return (0);
if (uio->uio_offset < 0) /* XXX VDIR cookies can be negative */
return (EINVAL);
td = uio->uio_td;
mtx_lock(&nmp->nm_mtx);
if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
(nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
mtx_unlock(&nmp->nm_mtx);
(void)nfs_fsinfo(nmp, vp, cred, td);
} else
mtx_unlock(&nmp->nm_mtx);
end = uio->uio_offset + uio->uio_resid;
if (vp->v_type != VDIR &&
(end > nmp->nm_maxfilesize || end < uio->uio_offset))
return (EFBIG);
if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
/* No caching/ no readaheads. Just read data into the user buffer */
return nfs_readrpc(vp, uio, cred);
biosize = vp->v_bufobj.bo_bsize;
seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
error = nfs_bioread_check_cons(vp, td, cred);
if (error)
return error;
do {
u_quad_t nsize;
mtx_lock(&np->n_mtx);
nsize = np->n_size;
mtx_unlock(&np->n_mtx);
switch (vp->v_type) {
case VREG:
nfsstats.biocache_reads++;
lbn = uio->uio_offset / biosize;
on = uio->uio_offset - (lbn * biosize);
/*
* Start the read ahead(s), as required.
*/
if (nmp->nm_readahead > 0) {
for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
(off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
rabn = lbn + 1 + nra;
if (incore(&vp->v_bufobj, rabn) == NULL) {
rabp = nfs_getcacheblk(vp, rabn, biosize, td);
if (!rabp) {
error = nfs_sigintr(nmp, td);
return (error ? error : EINTR);
}
if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
rabp->b_flags |= B_ASYNC;
rabp->b_iocmd = BIO_READ;
vfs_busy_pages(rabp, 0);
if (nfs_asyncio(nmp, rabp, cred, td)) {
rabp->b_flags |= B_INVAL;
rabp->b_ioflags |= BIO_ERROR;
vfs_unbusy_pages(rabp);
brelse(rabp);
break;
}
} else {
brelse(rabp);
}
}
}
}
/* Note that bcount is *not* DEV_BSIZE aligned. */
bcount = biosize;
if ((off_t)lbn * biosize >= nsize) {
bcount = 0;
} else if ((off_t)(lbn + 1) * biosize > nsize) {
bcount = nsize - (off_t)lbn * biosize;
}
bp = nfs_getcacheblk(vp, lbn, bcount, td);
if (!bp) {
error = nfs_sigintr(nmp, td);
return (error ? error : EINTR);
}
/*
* If B_CACHE is not set, we must issue the read. If this
* fails, we return an error.
*/
if ((bp->b_flags & B_CACHE) == 0) {
bp->b_iocmd = BIO_READ;
vfs_busy_pages(bp, 0);
error = nfs_doio(vp, bp, cred, td);
if (error) {
brelse(bp);
return (error);
}
}
/*
* on is the offset into the current bp. Figure out how many
* bytes we can copy out of the bp. Note that bcount is
* NOT DEV_BSIZE aligned.
*
* Then figure out how many bytes we can copy into the uio.
*/
n = 0;
if (on < bcount)
n = MIN((unsigned)(bcount - on), uio->uio_resid);
break;
case VLNK:
nfsstats.biocache_readlinks++;
bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
if (!bp) {
error = nfs_sigintr(nmp, td);
return (error ? error : EINTR);
}
if ((bp->b_flags & B_CACHE) == 0) {
bp->b_iocmd = BIO_READ;
vfs_busy_pages(bp, 0);
error = nfs_doio(vp, bp, cred, td);
if (error) {
bp->b_ioflags |= BIO_ERROR;
brelse(bp);
return (error);
}
}
n = MIN(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
on = 0;
break;
case VDIR:
nfsstats.biocache_readdirs++;
if (np->n_direofoffset
&& uio->uio_offset >= np->n_direofoffset) {
return (0);
}
lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
if (!bp) {
error = nfs_sigintr(nmp, td);
return (error ? error : EINTR);
}
if ((bp->b_flags & B_CACHE) == 0) {
bp->b_iocmd = BIO_READ;
vfs_busy_pages(bp, 0);
error = nfs_doio(vp, bp, cred, td);
if (error) {
brelse(bp);
}
while (error == NFSERR_BAD_COOKIE) {
(nmp->nm_rpcops->nr_invaldir)(vp);
error = nfs_vinvalbuf(vp, 0, td, 1);
/*
* Yuck! The directory has been modified on the
* server. The only way to get the block is by
* reading from the beginning to get all the
* offset cookies.
*
* Leave the last bp intact unless there is an error.
* Loop back up to the while if the error is another
* NFSERR_BAD_COOKIE (double yuch!).
*/
for (i = 0; i <= lbn && !error; i++) {
if (np->n_direofoffset
&& (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
return (0);
bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
if (!bp) {
error = nfs_sigintr(nmp, td);
return (error ? error : EINTR);
}
if ((bp->b_flags & B_CACHE) == 0) {
bp->b_iocmd = BIO_READ;
vfs_busy_pages(bp, 0);
error = nfs_doio(vp, bp, cred, td);
/*
* no error + B_INVAL == directory EOF,
* use the block.
*/
if (error == 0 && (bp->b_flags & B_INVAL))
break;
}
/*
* An error will throw away the block and the
* for loop will break out. If no error and this
* is not the block we want, we throw away the
* block and go for the next one via the for loop.
*/
if (error || i < lbn)
brelse(bp);
}
}
/*
* The above while is repeated if we hit another cookie
* error. If we hit an error and it wasn't a cookie error,
* we give up.
*/
if (error)
return (error);
}
/*
* If not eof and read aheads are enabled, start one.
* (You need the current block first, so that you have the
* directory offset cookie of the next block.)
*/
if (nmp->nm_readahead > 0 &&
(bp->b_flags & B_INVAL) == 0 &&
(np->n_direofoffset == 0 ||
(lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
incore(&vp->v_bufobj, lbn + 1) == NULL) {
rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
if (rabp) {
if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
rabp->b_flags |= B_ASYNC;
rabp->b_iocmd = BIO_READ;
vfs_busy_pages(rabp, 0);
if (nfs_asyncio(nmp, rabp, cred, td)) {
rabp->b_flags |= B_INVAL;
rabp->b_ioflags |= BIO_ERROR;
vfs_unbusy_pages(rabp);
brelse(rabp);
}
} else {
brelse(rabp);
}
}
}
/*
* Unlike VREG files, whos buffer size ( bp->b_bcount ) is
* chopped for the EOF condition, we cannot tell how large
* NFS directories are going to be until we hit EOF. So
* an NFS directory buffer is *not* chopped to its EOF. Now,
* it just so happens that b_resid will effectively chop it
* to EOF. *BUT* this information is lost if the buffer goes
* away and is reconstituted into a B_CACHE state ( due to
* being VMIO ) later. So we keep track of the directory eof
* in np->n_direofoffset and chop it off as an extra step
* right here.
*/
n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
n = np->n_direofoffset - uio->uio_offset;
break;
default:
nfs_printf(" nfs_bioread: type %x unexpected\n", vp->v_type);
bp = NULL;
break;
};
if (n > 0) {
error = uiomove(bp->b_data + on, (int)n, uio);
}
if (vp->v_type == VLNK)
n = 0;
if (bp != NULL)
brelse(bp);
} while (error == 0 && uio->uio_resid > 0 && n > 0);
return (error);
}
/*
* The NFS write path cannot handle iovecs with len > 1. So we need to
* break up iovecs accordingly (restricting them to wsize).
* For the SYNC case, we can do this with 1 copy (user buffer -> mbuf).
* For the ASYNC case, 2 copies are needed. The first a copy from the
* user buffer to a staging buffer and then a second copy from the staging
* buffer to mbufs. This can be optimized by copying from the user buffer
* directly into mbufs and passing the chain down, but that requires a
* fair amount of re-working of the relevant codepaths (and can be done
* later).
*/
static int
nfs_directio_write(vp, uiop, cred, ioflag)
struct vnode *vp;
struct uio *uiop;
struct ucred *cred;
int ioflag;
{
int error;
struct nfsmount *nmp = VFSTONFS(vp->v_mount);
struct thread *td = uiop->uio_td;
int size;
int wsize;
mtx_lock(&nmp->nm_mtx);
wsize = nmp->nm_wsize;
mtx_unlock(&nmp->nm_mtx);
if (ioflag & IO_SYNC) {
int iomode, must_commit;
struct uio uio;
struct iovec iov;
do_sync:
while (uiop->uio_resid > 0) {
size = MIN(uiop->uio_resid, wsize);
size = MIN(uiop->uio_iov->iov_len, size);
iov.iov_base = uiop->uio_iov->iov_base;
iov.iov_len = size;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = uiop->uio_offset;
uio.uio_resid = size;
uio.uio_segflg = UIO_USERSPACE;
uio.uio_rw = UIO_WRITE;
uio.uio_td = td;
iomode = NFSV3WRITE_FILESYNC;
error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred,
&iomode, &must_commit);
KASSERT((must_commit == 0),
("nfs_directio_write: Did not commit write"));
if (error)
return (error);
uiop->uio_offset += size;
uiop->uio_resid -= size;
if (uiop->uio_iov->iov_len <= size) {
uiop->uio_iovcnt--;
uiop->uio_iov++;
} else {
uiop->uio_iov->iov_base =
(char *)uiop->uio_iov->iov_base + size;
uiop->uio_iov->iov_len -= size;
}
}
} else {
struct uio *t_uio;
struct iovec *t_iov;
struct buf *bp;
/*
* Break up the write into blocksize chunks and hand these
* over to nfsiod's for write back.
* Unfortunately, this incurs a copy of the data. Since
* the user could modify the buffer before the write is
* initiated.
*
* The obvious optimization here is that one of the 2 copies
* in the async write path can be eliminated by copying the
* data here directly into mbufs and passing the mbuf chain
* down. But that will require a fair amount of re-working
* of the code and can be done if there's enough interest
* in NFS directio access.
*/
while (uiop->uio_resid > 0) {
size = MIN(uiop->uio_resid, wsize);
size = MIN(uiop->uio_iov->iov_len, size);
bp = getpbuf(&nfs_pbuf_freecnt);
t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
t_iov->iov_len = size;
t_uio->uio_iov = t_iov;
t_uio->uio_iovcnt = 1;
t_uio->uio_offset = uiop->uio_offset;
t_uio->uio_resid = size;
t_uio->uio_segflg = UIO_SYSSPACE;
t_uio->uio_rw = UIO_WRITE;
t_uio->uio_td = td;
KASSERT(uiop->uio_segflg == UIO_USERSPACE ||
uiop->uio_segflg == UIO_SYSSPACE,
("nfs_directio_write: Bad uio_segflg"));
if (uiop->uio_segflg == UIO_USERSPACE) {
error = copyin(uiop->uio_iov->iov_base,
t_iov->iov_base, size);
if (error != 0)
goto err_free;
} else
/*
* UIO_SYSSPACE may never happen, but handle
* it just in case it does.
*/
bcopy(uiop->uio_iov->iov_base, t_iov->iov_base,
size);
bp->b_flags |= B_DIRECT;
bp->b_iocmd = BIO_WRITE;
if (cred != NOCRED) {
crhold(cred);
bp->b_wcred = cred;
} else
bp->b_wcred = NOCRED;
bp->b_caller1 = (void *)t_uio;
bp->b_vp = vp;
error = nfs_asyncio(nmp, bp, NOCRED, td);
err_free:
if (error) {
free(t_iov->iov_base, M_NFSDIRECTIO);
free(t_iov, M_NFSDIRECTIO);
free(t_uio, M_NFSDIRECTIO);
bp->b_vp = NULL;
relpbuf(bp, &nfs_pbuf_freecnt);
if (error == EINTR)
return (error);
goto do_sync;
}
uiop->uio_offset += size;
uiop->uio_resid -= size;
if (uiop->uio_iov->iov_len <= size) {
uiop->uio_iovcnt--;
uiop->uio_iov++;
} else {
uiop->uio_iov->iov_base =
(char *)uiop->uio_iov->iov_base + size;
uiop->uio_iov->iov_len -= size;
}
}
}
return (0);
}
/*
* Vnode op for write using bio
*/
int
nfs_write(struct vop_write_args *ap)
{
int biosize;
struct uio *uio = ap->a_uio;
struct thread *td = uio->uio_td;
struct vnode *vp = ap->a_vp;
struct nfsnode *np = VTONFS(vp);
struct ucred *cred = ap->a_cred;
int ioflag = ap->a_ioflag;
struct buf *bp;
struct vattr vattr;
struct nfsmount *nmp = VFSTONFS(vp->v_mount);
daddr_t lbn;
off_t end;
int bcount;
int n, on, error = 0;
KASSERT(uio->uio_rw == UIO_WRITE, ("nfs_write mode"));
KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
("nfs_write proc"));
if (vp->v_type != VREG)
return (EIO);
mtx_lock(&np->n_mtx);
if (np->n_flag & NWRITEERR) {
np->n_flag &= ~NWRITEERR;
mtx_unlock(&np->n_mtx);
return (np->n_error);
} else
mtx_unlock(&np->n_mtx);
mtx_lock(&nmp->nm_mtx);
if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
(nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
mtx_unlock(&nmp->nm_mtx);
(void)nfs_fsinfo(nmp, vp, cred, td);
} else
mtx_unlock(&nmp->nm_mtx);
/*
* Synchronously flush pending buffers if we are in synchronous
* mode or if we are appending.
*/
if (ioflag & (IO_APPEND | IO_SYNC)) {
mtx_lock(&np->n_mtx);
if (np->n_flag & NMODIFIED) {
mtx_unlock(&np->n_mtx);
#ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
/*
* Require non-blocking, synchronous writes to
* dirty files to inform the program it needs
* to fsync(2) explicitly.
*/
if (ioflag & IO_NDELAY)
return (EAGAIN);
#endif
flush_and_restart:
np->n_attrstamp = 0;
KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
if (error)
return (error);
} else
mtx_unlock(&np->n_mtx);
}
/*
* If IO_APPEND then load uio_offset. We restart here if we cannot
* get the append lock.
*/
if (ioflag & IO_APPEND) {
np->n_attrstamp = 0;
KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
error = VOP_GETATTR(vp, &vattr, cred);
if (error)
return (error);
mtx_lock(&np->n_mtx);
uio->uio_offset = np->n_size;
mtx_unlock(&np->n_mtx);
}
if (uio->uio_offset < 0)
return (EINVAL);
end = uio->uio_offset + uio->uio_resid;
if (end > nmp->nm_maxfilesize || end < uio->uio_offset)
return (EFBIG);
if (uio->uio_resid == 0)
return (0);
if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
return nfs_directio_write(vp, uio, cred, ioflag);
/*
* Maybe this should be above the vnode op call, but so long as
* file servers have no limits, i don't think it matters
*/
if (vn_rlimit_fsize(vp, uio, td))
return (EFBIG);
biosize = vp->v_bufobj.bo_bsize;
/*
* Find all of this file's B_NEEDCOMMIT buffers. If our writes
* would exceed the local maximum per-file write commit size when
* combined with those, we must decide whether to flush,
* go synchronous, or return error. We don't bother checking
* IO_UNIT -- we just make all writes atomic anyway, as there's
* no point optimizing for something that really won't ever happen.
*/
if (!(ioflag & IO_SYNC)) {
int nflag;
mtx_lock(&np->n_mtx);
nflag = np->n_flag;
mtx_unlock(&np->n_mtx);
int needrestart = 0;
if (nmp->nm_wcommitsize < uio->uio_resid) {
/*
* If this request could not possibly be completed
* without exceeding the maximum outstanding write
* commit size, see if we can convert it into a
* synchronous write operation.
*/
if (ioflag & IO_NDELAY)
return (EAGAIN);
ioflag |= IO_SYNC;
if (nflag & NMODIFIED)
needrestart = 1;
} else if (nflag & NMODIFIED) {
int wouldcommit = 0;
BO_LOCK(&vp->v_bufobj);
if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
b_bobufs) {
if (bp->b_flags & B_NEEDCOMMIT)
wouldcommit += bp->b_bcount;
}
}
BO_UNLOCK(&vp->v_bufobj);
/*
* Since we're not operating synchronously and
* bypassing the buffer cache, we are in a commit
* and holding all of these buffers whether
* transmitted or not. If not limited, this
* will lead to the buffer cache deadlocking,
* as no one else can flush our uncommitted buffers.
*/
wouldcommit += uio->uio_resid;
/*
* If we would initially exceed the maximum
* outstanding write commit size, flush and restart.
*/
if (wouldcommit > nmp->nm_wcommitsize)
needrestart = 1;
}
if (needrestart)
goto flush_and_restart;
}
do {
nfsstats.biocache_writes++;
lbn = uio->uio_offset / biosize;
on = uio->uio_offset - (lbn * biosize);
n = MIN((unsigned)(biosize - on), uio->uio_resid);
again:
/*
* Handle direct append and file extension cases, calculate
* unaligned buffer size.
*/
mtx_lock(&np->n_mtx);
if (uio->uio_offset == np->n_size && n) {
mtx_unlock(&np->n_mtx);
/*
* Get the buffer (in its pre-append state to maintain
* B_CACHE if it was previously set). Resize the
* nfsnode after we have locked the buffer to prevent
* readers from reading garbage.
*/
bcount = on;
bp = nfs_getcacheblk(vp, lbn, bcount, td);
if (bp != NULL) {
long save;
mtx_lock(&np->n_mtx);
np->n_size = uio->uio_offset + n;
np->n_flag |= NMODIFIED;
vnode_pager_setsize(vp, np->n_size);
mtx_unlock(&np->n_mtx);
save = bp->b_flags & B_CACHE;
bcount += n;
allocbuf(bp, bcount);
bp->b_flags |= save;
}
} else {
/*
* Obtain the locked cache block first, and then
* adjust the file's size as appropriate.
*/
bcount = on + n;
if ((off_t)lbn * biosize + bcount < np->n_size) {
if ((off_t)(lbn + 1) * biosize < np->n_size)
bcount = biosize;
else
bcount = np->n_size - (off_t)lbn * biosize;
}
mtx_unlock(&np->n_mtx);
bp = nfs_getcacheblk(vp, lbn, bcount, td);
mtx_lock(&np->n_mtx);
if (uio->uio_offset + n > np->n_size) {
np->n_size = uio->uio_offset + n;
np->n_flag |= NMODIFIED;
vnode_pager_setsize(vp, np->n_size);
}
mtx_unlock(&np->n_mtx);
}
if (!bp) {
error = nfs_sigintr(nmp, td);
if (!error)
error = EINTR;
break;
}
/*
* Issue a READ if B_CACHE is not set. In special-append
* mode, B_CACHE is based on the buffer prior to the write
* op and is typically set, avoiding the read. If a read
* is required in special append mode, the server will
* probably send us a short-read since we extended the file
* on our end, resulting in b_resid == 0 and, thusly,
* B_CACHE getting set.
*
* We can also avoid issuing the read if the write covers
* the entire buffer. We have to make sure the buffer state
* is reasonable in this case since we will not be initiating
* I/O. See the comments in kern/vfs_bio.c's getblk() for
* more information.
*
* B_CACHE may also be set due to the buffer being cached
* normally.
*/
if (on == 0 && n == bcount) {
bp->b_flags |= B_CACHE;
bp->b_flags &= ~B_INVAL;
bp->b_ioflags &= ~BIO_ERROR;
}
if ((bp->b_flags & B_CACHE) == 0) {
bp->b_iocmd = BIO_READ;
vfs_busy_pages(bp, 0);
error = nfs_doio(vp, bp, cred, td);
if (error) {
brelse(bp);
break;
}
}
if (bp->b_wcred == NOCRED)
bp->b_wcred = crhold(cred);
mtx_lock(&np->n_mtx);
np->n_flag |= NMODIFIED;
mtx_unlock(&np->n_mtx);
/*
* If dirtyend exceeds file size, chop it down. This should
* not normally occur but there is an append race where it
* might occur XXX, so we log it.
*
* If the chopping creates a reverse-indexed or degenerate
* situation with dirtyoff/end, we 0 both of them.
*/
if (bp->b_dirtyend > bcount) {
nfs_printf("NFS append race @%lx:%d\n",
(long)bp->b_blkno * DEV_BSIZE,
bp->b_dirtyend - bcount);
bp->b_dirtyend = bcount;
}
if (bp->b_dirtyoff >= bp->b_dirtyend)
bp->b_dirtyoff = bp->b_dirtyend = 0;
/*
* If the new write will leave a contiguous dirty
* area, just update the b_dirtyoff and b_dirtyend,
* otherwise force a write rpc of the old dirty area.
*
* While it is possible to merge discontiguous writes due to
* our having a B_CACHE buffer ( and thus valid read data
* for the hole), we don't because it could lead to
* significant cache coherency problems with multiple clients,
* especially if locking is implemented later on.
*
* as an optimization we could theoretically maintain
* a linked list of discontinuous areas, but we would still
* have to commit them separately so there isn't much
* advantage to it except perhaps a bit of asynchronization.
*/
if (bp->b_dirtyend > 0 &&
(on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
if (bwrite(bp) == EINTR) {
error = EINTR;
break;
}
goto again;
}
error = uiomove((char *)bp->b_data + on, n, uio);
/*
* Since this block is being modified, it must be written
* again and not just committed. Since write clustering does
* not work for the stage 1 data write, only the stage 2
* commit rpc, we have to clear B_CLUSTEROK as well.
*/
bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
if (error) {
bp->b_ioflags |= BIO_ERROR;
brelse(bp);
break;
}
/*
* Only update dirtyoff/dirtyend if not a degenerate
* condition.
*/
if (n) {
if (bp->b_dirtyend > 0) {
bp->b_dirtyoff = min(on, bp->b_dirtyoff);
bp->b_dirtyend = max((on + n), bp->b_dirtyend);
} else {
bp->b_dirtyoff = on;
bp->b_dirtyend = on + n;
}
vfs_bio_set_valid(bp, on, n);
}
/*
* If IO_SYNC do bwrite().
*
* IO_INVAL appears to be unused. The idea appears to be
* to turn off caching in this case. Very odd. XXX
*/
if ((ioflag & IO_SYNC)) {
if (ioflag & IO_INVAL)
bp->b_flags |= B_NOCACHE;
error = bwrite(bp);
if (error)
break;
} else if ((n + on) == biosize) {
bp->b_flags |= B_ASYNC;
(void) (nmp->nm_rpcops->nr_writebp)(bp, 0, NULL);
} else {
bdwrite(bp);
}
} while (uio->uio_resid > 0 && n > 0);
return (error);
}
/*
* Get an nfs cache block.
*
* Allocate a new one if the block isn't currently in the cache
* and return the block marked busy. If the calling process is
* interrupted by a signal for an interruptible mount point, return
* NULL.
*
* The caller must carefully deal with the possible B_INVAL state of
* the buffer. nfs_doio() clears B_INVAL (and nfs_asyncio() clears it
* indirectly), so synchronous reads can be issued without worrying about
* the B_INVAL state. We have to be a little more careful when dealing
* with writes (see comments in nfs_write()) when extending a file past
* its EOF.
*/
static struct buf *
nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
{
struct buf *bp;
struct mount *mp;
struct nfsmount *nmp;
mp = vp->v_mount;
nmp = VFSTONFS(mp);
if (nmp->nm_flag & NFSMNT_INT) {
sigset_t oldset;
nfs_set_sigmask(td, &oldset);
bp = getblk(vp, bn, size, PCATCH, 0, 0);
nfs_restore_sigmask(td, &oldset);
while (bp == NULL) {
if (nfs_sigintr(nmp, td))
return (NULL);
bp = getblk(vp, bn, size, 0, 2 * hz, 0);
}
} else {
bp = getblk(vp, bn, size, 0, 0, 0);
}
if (vp->v_type == VREG)
bp->b_blkno = bn * (vp->v_bufobj.bo_bsize / DEV_BSIZE);
return (bp);
}
/*
* Flush and invalidate all dirty buffers. If another process is already
* doing the flush, just wait for completion.
*/
int
nfs_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
{
struct nfsnode *np = VTONFS(vp);
struct nfsmount *nmp = VFSTONFS(vp->v_mount);
int error = 0, slpflag, slptimeo;
int old_lock = 0;
ASSERT_VOP_LOCKED(vp, "nfs_vinvalbuf");
if ((nmp->nm_flag & NFSMNT_INT) == 0)
intrflg = 0;
if (intrflg) {
slpflag = PCATCH;
slptimeo = 2 * hz;
} else {
slpflag = 0;
slptimeo = 0;
}
old_lock = nfs_upgrade_vnlock(vp);
if (vp->v_iflag & VI_DOOMED) {
/*
* Since vgonel() uses the generic vinvalbuf() to flush
* dirty buffers and it does not call this function, it
* is safe to just return OK when VI_DOOMED is set.
*/
nfs_downgrade_vnlock(vp, old_lock);
return (0);
}
/*
* Now, flush as required.
*/
if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
VM_OBJECT_WLOCK(vp->v_bufobj.bo_object);
vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
VM_OBJECT_WUNLOCK(vp->v_bufobj.bo_object);
/*
* If the page clean was interrupted, fail the invalidation.
* Not doing so, we run the risk of losing dirty pages in the
* vinvalbuf() call below.
*/
if (intrflg && (error = nfs_sigintr(nmp, td)))
goto out;
}
error = vinvalbuf(vp, flags, slpflag, 0);
while (error) {
if (intrflg && (error = nfs_sigintr(nmp, td)))
goto out;
error = vinvalbuf(vp, flags, 0, slptimeo);
}
mtx_lock(&np->n_mtx);
if (np->n_directio_asyncwr == 0)
np->n_flag &= ~NMODIFIED;
mtx_unlock(&np->n_mtx);
out:
nfs_downgrade_vnlock(vp, old_lock);
return error;
}
/*
* Initiate asynchronous I/O. Return an error if no nfsiods are available.
* This is mainly to avoid queueing async I/O requests when the nfsiods
* are all hung on a dead server.
*
* Note: nfs_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
* is eventually dequeued by the async daemon, nfs_doio() *will*.
*/
int
nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
{
int iod;
int gotiod;
int slpflag = 0;
int slptimeo = 0;
int error, error2;
/*
* Commits are usually short and sweet so lets save some cpu and
* leave the async daemons for more important rpc's (such as reads
* and writes).
*
* Readdirplus RPCs do vget()s to acquire the vnodes for entries
* in the directory in order to update attributes. This can deadlock
* with another thread that is waiting for async I/O to be done by
* an nfsiod thread while holding a lock on one of these vnodes.
* To avoid this deadlock, don't allow the async nfsiod threads to
* perform Readdirplus RPCs.
*/
mtx_lock(&nfs_iod_mtx);
if ((bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
(nmp->nm_bufqiods > nfs_numasync / 2)) ||
(bp->b_vp->v_type == VDIR && (nmp->nm_flag & NFSMNT_RDIRPLUS))) {
mtx_unlock(&nfs_iod_mtx);
return(EIO);
}
again:
if (nmp->nm_flag & NFSMNT_INT)
slpflag = PCATCH;
gotiod = FALSE;
/*
* Find a free iod to process this request.
*/
for (iod = 0; iod < nfs_numasync; iod++)
if (nfs_iodwant[iod] == NFSIOD_AVAILABLE) {
gotiod = TRUE;
break;
}
/*
* Try to create one if none are free.
*/
if (!gotiod)
nfs_nfsiodnew();
else {
/*
* Found one, so wake it up and tell it which
* mount to process.
*/
NFS_DPF(ASYNCIO, ("nfs_asyncio: waking iod %d for mount %p\n",
iod, nmp));
nfs_iodwant[iod] = NFSIOD_NOT_AVAILABLE;
nfs_iodmount[iod] = nmp;
nmp->nm_bufqiods++;
wakeup(&nfs_iodwant[iod]);
}
/*
* If none are free, we may already have an iod working on this mount
* point. If so, it will process our request.
*/
if (!gotiod) {
if (nmp->nm_bufqiods > 0) {
NFS_DPF(ASYNCIO,
("nfs_asyncio: %d iods are already processing mount %p\n",
nmp->nm_bufqiods, nmp));
gotiod = TRUE;
}
}
/*
* If we have an iod which can process the request, then queue
* the buffer.
*/
if (gotiod) {
/*
* Ensure that the queue never grows too large. We still want
* to asynchronize so we block rather then return EIO.
*/
while (nmp->nm_bufqlen >= 2 * nfs_numasync) {
NFS_DPF(ASYNCIO,
("nfs_asyncio: waiting for mount %p queue to drain\n", nmp));
nmp->nm_bufqwant = TRUE;
error = nfs_msleep(td, &nmp->nm_bufq, &nfs_iod_mtx,
slpflag | PRIBIO,
"nfsaio", slptimeo);
if (error) {
error2 = nfs_sigintr(nmp, td);
if (error2) {
mtx_unlock(&nfs_iod_mtx);
return (error2);
}
if (slpflag == PCATCH) {
slpflag = 0;
slptimeo = 2 * hz;
}
}
/*
* We might have lost our iod while sleeping,
* so check and loop if nescessary.
*/
goto again;
}
/* We might have lost our nfsiod */
if (nmp->nm_bufqiods == 0) {
NFS_DPF(ASYNCIO,
("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
goto again;
}
if (bp->b_iocmd == BIO_READ) {
if (bp->b_rcred == NOCRED && cred != NOCRED)
bp->b_rcred = crhold(cred);
} else {
if (bp->b_wcred == NOCRED && cred != NOCRED)
bp->b_wcred = crhold(cred);
}
if (bp->b_flags & B_REMFREE)
bremfreef(bp);
BUF_KERNPROC(bp);
TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
nmp->nm_bufqlen++;
if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);
VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
VTONFS(bp->b_vp)->n_directio_asyncwr++;
mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
}
mtx_unlock(&nfs_iod_mtx);
return (0);
}
mtx_unlock(&nfs_iod_mtx);
/*
* All the iods are busy on other mounts, so return EIO to
* force the caller to process the i/o synchronously.
*/
NFS_DPF(ASYNCIO, ("nfs_asyncio: no iods available, i/o is synchronous\n"));
return (EIO);
}
void
nfs_doio_directwrite(struct buf *bp)
{
int iomode, must_commit;
struct uio *uiop = (struct uio *)bp->b_caller1;
char *iov_base = uiop->uio_iov->iov_base;
struct nfsmount *nmp = VFSTONFS(bp->b_vp->v_mount);
iomode = NFSV3WRITE_FILESYNC;
uiop->uio_td = NULL; /* NULL since we're in nfsiod */
(nmp->nm_rpcops->nr_writerpc)(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
KASSERT((must_commit == 0), ("nfs_doio_directwrite: Did not commit write"));
free(iov_base, M_NFSDIRECTIO);
free(uiop->uio_iov, M_NFSDIRECTIO);
free(uiop, M_NFSDIRECTIO);
if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
struct nfsnode *np = VTONFS(bp->b_vp);
mtx_lock(&np->n_mtx);
np->n_directio_asyncwr--;
if (np->n_directio_asyncwr == 0) {
VTONFS(bp->b_vp)->n_flag &= ~NMODIFIED;
if ((np->n_flag & NFSYNCWAIT)) {
np->n_flag &= ~NFSYNCWAIT;
wakeup((caddr_t)&np->n_directio_asyncwr);
}
}
mtx_unlock(&np->n_mtx);
}
bp->b_vp = NULL;
relpbuf(bp, &nfs_pbuf_freecnt);
}
/*
* Do an I/O operation to/from a cache block. This may be called
* synchronously or from an nfsiod.
*/
int
nfs_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
{
struct uio *uiop;
struct nfsnode *np;
struct nfsmount *nmp;
int error = 0, iomode, must_commit = 0;
struct uio uio;
struct iovec io;
struct proc *p = td ? td->td_proc : NULL;
uint8_t iocmd;
np = VTONFS(vp);
nmp = VFSTONFS(vp->v_mount);
uiop = &uio;
uiop->uio_iov = &io;
uiop->uio_iovcnt = 1;
uiop->uio_segflg = UIO_SYSSPACE;
uiop->uio_td = td;
/*
* clear BIO_ERROR and B_INVAL state prior to initiating the I/O. We
* do this here so we do not have to do it in all the code that
* calls us.
*/
bp->b_flags &= ~B_INVAL;
bp->b_ioflags &= ~BIO_ERROR;
KASSERT(!(bp->b_flags & B_DONE), ("nfs_doio: bp %p already marked done", bp));
iocmd = bp->b_iocmd;
if (iocmd == BIO_READ) {
io.iov_len = uiop->uio_resid = bp->b_bcount;
io.iov_base = bp->b_data;
uiop->uio_rw = UIO_READ;
switch (vp->v_type) {
case VREG:
uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
nfsstats.read_bios++;
error = (nmp->nm_rpcops->nr_readrpc)(vp, uiop, cr);
if (!error) {
if (uiop->uio_resid) {
/*
* If we had a short read with no error, we must have
* hit a file hole. We should zero-fill the remainder.
* This can also occur if the server hits the file EOF.
*
* Holes used to be able to occur due to pending
* writes, but that is not possible any longer.
*/
int nread = bp->b_bcount - uiop->uio_resid;
int left = uiop->uio_resid;
if (left > 0)
bzero((char *)bp->b_data + nread, left);
uiop->uio_resid = 0;
}
}
/* ASSERT_VOP_LOCKED(vp, "nfs_doio"); */
if (p && (vp->v_vflag & VV_TEXT)) {
mtx_lock(&np->n_mtx);
if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.va_mtime)) {
mtx_unlock(&np->n_mtx);
PROC_LOCK(p);
killproc(p, "text file modification");
PROC_UNLOCK(p);
} else
mtx_unlock(&np->n_mtx);
}
break;
case VLNK:
uiop->uio_offset = (off_t)0;
nfsstats.readlink_bios++;
error = (nmp->nm_rpcops->nr_readlinkrpc)(vp, uiop, cr);
break;
case VDIR:
nfsstats.readdir_bios++;
uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
error = nfs_readdirplusrpc(vp, uiop, cr);
if (error == NFSERR_NOTSUPP)
nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
}
if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
error = nfs_readdirrpc(vp, uiop, cr);
/*
* end-of-directory sets B_INVAL but does not generate an
* error.
*/
if (error == 0 && uiop->uio_resid == bp->b_bcount)
bp->b_flags |= B_INVAL;
break;
default:
nfs_printf("nfs_doio: type %x unexpected\n", vp->v_type);
break;
};
if (error) {
bp->b_ioflags |= BIO_ERROR;
bp->b_error = error;
}
} else {
/*
* If we only need to commit, try to commit
*/
if (bp->b_flags & B_NEEDCOMMIT) {
int retv;
off_t off;
off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
retv = (nmp->nm_rpcops->nr_commit)(
vp, off, bp->b_dirtyend-bp->b_dirtyoff,
bp->b_wcred, td);
if (retv == 0) {
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
bp->b_resid = 0;
bufdone(bp);
return (0);
}
if (retv == NFSERR_STALEWRITEVERF) {
nfs_clearcommit(vp->v_mount);
}
}
/*
* Setup for actual write
*/
mtx_lock(&np->n_mtx);
if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
mtx_unlock(&np->n_mtx);
if (bp->b_dirtyend > bp->b_dirtyoff) {
io.iov_len = uiop->uio_resid = bp->b_dirtyend
- bp->b_dirtyoff;
uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
+ bp->b_dirtyoff;
io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
uiop->uio_rw = UIO_WRITE;
nfsstats.write_bios++;
if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
iomode = NFSV3WRITE_UNSTABLE;
else
iomode = NFSV3WRITE_FILESYNC;
error = (nmp->nm_rpcops->nr_writerpc)(vp, uiop, cr, &iomode, &must_commit);
/*
* When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
* to cluster the buffers needing commit. This will allow
* the system to submit a single commit rpc for the whole
* cluster. We can do this even if the buffer is not 100%
* dirty (relative to the NFS blocksize), so we optimize the
* append-to-file-case.
*
* (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
* cleared because write clustering only works for commit
* rpc's, not for the data portion of the write).
*/
if (!error && iomode == NFSV3WRITE_UNSTABLE) {
bp->b_flags |= B_NEEDCOMMIT;
if (bp->b_dirtyoff == 0
&& bp->b_dirtyend == bp->b_bcount)
bp->b_flags |= B_CLUSTEROK;
} else {
bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
}
/*
* For an interrupted write, the buffer is still valid
* and the write hasn't been pushed to the server yet,
* so we can't set BIO_ERROR and report the interruption
* by setting B_EINTR. For the B_ASYNC case, B_EINTR
* is not relevant, so the rpc attempt is essentially
* a noop. For the case of a V3 write rpc not being
* committed to stable storage, the block is still
* dirty and requires either a commit rpc or another
* write rpc with iomode == NFSV3WRITE_FILESYNC before
* the block is reused. This is indicated by setting
* the B_DELWRI and B_NEEDCOMMIT flags.
*
* If the buffer is marked B_PAGING, it does not reside on
* the vp's paging queues so we cannot call bdirty(). The
* bp in this case is not an NFS cache block so we should
* be safe. XXX
*
* The logic below breaks up errors into recoverable and
* unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
* and keep the buffer around for potential write retries.
* For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
* and save the error in the nfsnode. This is less than ideal
* but necessary. Keeping such buffers around could potentially
* cause buffer exhaustion eventually (they can never be written
* out, so will get constantly be re-dirtied). It also causes
* all sorts of vfs panics. For non-recoverable write errors,
* also invalidate the attrcache, so we'll be forced to go over
* the wire for this object, returning an error to user on next
* call (most of the time).
*/
if (error == EINTR || error == EIO || error == ETIMEDOUT
|| (!error && (bp->b_flags & B_NEEDCOMMIT))) {
int s;
s = splbio();
bp->b_flags &= ~(B_INVAL|B_NOCACHE);
if ((bp->b_flags & B_PAGING) == 0) {
bdirty(bp);
bp->b_flags &= ~B_DONE;
}
if (error && (bp->b_flags & B_ASYNC) == 0)
bp->b_flags |= B_EINTR;
splx(s);
} else {
if (error) {
bp->b_ioflags |= BIO_ERROR;
bp->b_flags |= B_INVAL;
bp->b_error = np->n_error = error;
mtx_lock(&np->n_mtx);
np->n_flag |= NWRITEERR;
np->n_attrstamp = 0;
KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
mtx_unlock(&np->n_mtx);
}
bp->b_dirtyoff = bp->b_dirtyend = 0;
}
} else {
bp->b_resid = 0;
bufdone(bp);
return (0);
}
}
bp->b_resid = uiop->uio_resid;
if (must_commit)
nfs_clearcommit(vp->v_mount);
bufdone(bp);
return (error);
}
/*
* Used to aid in handling ftruncate() operations on the NFS client side.
* Truncation creates a number of special problems for NFS. We have to
* throw away VM pages and buffer cache buffers that are beyond EOF, and
* we have to properly handle VM pages or (potentially dirty) buffers
* that straddle the truncation point.
*/
int
nfs_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
{
struct nfsnode *np = VTONFS(vp);
u_quad_t tsize;
int biosize = vp->v_bufobj.bo_bsize;
int error = 0;
mtx_lock(&np->n_mtx);
tsize = np->n_size;
np->n_size = nsize;
mtx_unlock(&np->n_mtx);
if (nsize < tsize) {
struct buf *bp;
daddr_t lbn;
int bufsize;
/*
* vtruncbuf() doesn't get the buffer overlapping the
* truncation point. We may have a B_DELWRI and/or B_CACHE
* buffer that now needs to be truncated.
*/
error = vtruncbuf(vp, cred, nsize, biosize);
lbn = nsize / biosize;
bufsize = nsize - (lbn * biosize);
bp = nfs_getcacheblk(vp, lbn, bufsize, td);
if (!bp)
return EINTR;
if (bp->b_dirtyoff > bp->b_bcount)
bp->b_dirtyoff = bp->b_bcount;
if (bp->b_dirtyend > bp->b_bcount)
bp->b_dirtyend = bp->b_bcount;
bp->b_flags |= B_RELBUF; /* don't leave garbage around */
brelse(bp);
} else {
vnode_pager_setsize(vp, nsize);
}
return(error);
}
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