First cut of NFS direct IO support.
- NFS direct IO completely bypasses the buffer and page caches. If a file is open for direct IO all caching is disabled. - Direct IO for Directories will be addressed later. - 2 new NFS directio related sysctls are added. One is a knob to disable NFS direct IO completely (direct IO is enabled by default). The other is to disallow mmaped IO on a file that has at least one O_DIRECT open (see the comment in nfs_vnops.c for more details). The default is to allow mmaps on a file that has O_DIRECT opens. Submitted by: Mohan Srinivasan mohans at yahoo-inc dot com Obtained from: Yahoo!
This commit is contained in:
ps
parent
3241f61d0e
commit
892d9ab784
@ -124,6 +124,7 @@ MALLOC_DECLARE(M_NFSREQ);
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MALLOC_DECLARE(M_NFSDIROFF);
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MALLOC_DECLARE(M_NFSBIGFH);
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MALLOC_DECLARE(M_NFSHASH);
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MALLOC_DECLARE(M_NFSDIRECTIO);
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#endif
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extern struct uma_zone *nfsmount_zone;
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@ -275,6 +276,7 @@ int nfs_readdirrpc(struct vnode *, struct uio *, struct ucred *);
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int nfs_nfsiodnew(void);
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int nfs_asyncio(struct nfsmount *, struct buf *, struct ucred *, struct thread *);
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int nfs_doio(struct vnode *, struct buf *, struct ucred *, struct thread *);
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void nfs_doio_directwrite (struct buf *);
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void nfs_up(struct nfsreq *, struct nfsmount *, struct thread *,
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const char *, int);
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void nfs_down(struct nfsreq *, struct nfsmount *, struct thread *,
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@ -66,7 +66,11 @@ __FBSDID("$FreeBSD$");
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static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
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struct thread *td);
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static int nfs_directio_write(struct vnode *vp, struct uio *uiop,
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struct ucred *cred, int ioflag);
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extern int nfs_directio_enable;
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extern int nfs_directio_allow_mmap;
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/*
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* Vnode op for VM getpages.
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*/
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@ -84,10 +88,12 @@ nfs_getpages(struct vop_getpages_args *ap)
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struct nfsmount *nmp;
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vm_object_t object;
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vm_page_t *pages;
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struct nfsnode *np;
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GIANT_REQUIRED;
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vp = ap->a_vp;
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np = VTONFS(vp);
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td = curthread; /* XXX */
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cred = curthread->td_ucred; /* XXX */
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nmp = VFSTONFS(vp->v_mount);
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@ -99,6 +105,12 @@ nfs_getpages(struct vop_getpages_args *ap)
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return VM_PAGER_ERROR;
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}
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if (!nfs_directio_allow_mmap && (np->n_flag & NNONCACHE) &&
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(vp->v_type == VREG)) {
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printf("nfs_getpages: called on non-cacheable vnode??\n");
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return VM_PAGER_ERROR;
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}
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if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
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(nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
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/* We'll never get here for v4, because we always have fsinfo */
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@ -275,6 +287,10 @@ nfs_putpages(struct vop_putpages_args *ap)
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(void)nfs_fsinfo(nmp, vp, cred, td);
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}
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if (!nfs_directio_allow_mmap && (np->n_flag & NNONCACHE) &&
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(vp->v_type == VREG))
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printf("nfs_putpages: called on noncache-able vnode??\n");
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for (i = 0; i < npages; i++)
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rtvals[i] = VM_PAGER_AGAIN;
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@ -365,6 +381,11 @@ nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
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if (vp->v_type != VDIR &&
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(uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
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return (EFBIG);
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if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
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/* No caching/ no readaheads. Just read data into the user buffer */
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return nfs_readrpc(vp, uio, cred);
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biosize = vp->v_mount->mnt_stat.f_iosize;
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seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
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/*
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@ -683,6 +704,136 @@ nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
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return (error);
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}
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/*
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* The NFS write path cannot handle iovecs with len > 1. So we need to
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* break up iovecs accordingly (restricting them to wsize).
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* For the SYNC case, we can do this with 1 copy (user buffer -> mbuf).
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* For the ASYNC case, 2 copies are needed. The first a copy from the
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* user buffer to a staging buffer and then a second copy from the staging
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* buffer to mbufs. This can be optimized by copying from the user buffer
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* directly into mbufs and passing the chain down, but that requires a
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* fair amount of re-working of the relevant codepaths (and can be done
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* later).
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*/
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static int
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nfs_directio_write(vp, uiop, cred, ioflag)
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struct vnode *vp;
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struct uio *uiop;
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struct ucred *cred;
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int ioflag;
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{
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int error;
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struct nfsmount *nmp = VFSTONFS(vp->v_mount);
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struct thread *td = uiop->uio_td;
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int size;
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if (ioflag & IO_SYNC) {
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int iomode, must_commit;
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struct uio uio;
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struct iovec iov;
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do_sync:
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while (uiop->uio_resid > 0) {
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size = min(uiop->uio_resid, nmp->nm_wsize);
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size = min(uiop->uio_iov->iov_len, size);
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iov.iov_base = uiop->uio_iov->iov_base;
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iov.iov_len = size;
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uio.uio_iov = &iov;
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uio.uio_iovcnt = 1;
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uio.uio_offset = uiop->uio_offset;
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uio.uio_resid = size;
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uio.uio_segflg = UIO_USERSPACE;
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uio.uio_rw = UIO_WRITE;
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uio.uio_td = td;
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iomode = NFSV3WRITE_FILESYNC;
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error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred,
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&iomode, &must_commit);
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KASSERT((must_commit == 0),
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("nfs_directio_write: Did not commit write"));
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if (error)
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return (error);
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uiop->uio_offset += size;
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uiop->uio_resid -= size;
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if (uiop->uio_iov->iov_len <= size) {
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uiop->uio_iovcnt--;
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uiop->uio_iov++;
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} else {
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uiop->uio_iov->iov_base =
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(char *)uiop->uio_iov->iov_base + size;
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uiop->uio_iov->iov_len -= size;
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}
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}
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} else {
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struct uio *t_uio;
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struct iovec *t_iov;
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struct buf *bp;
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/*
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* Break up the write into blocksize chunks and hand these
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* over to nfsiod's for write back.
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* Unfortunately, this incurs a copy of the data. Since
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* the user could modify the buffer before the write is
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* initiated.
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*
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* The obvious optimization here is that one of the 2 copies
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* in the async write path can be eliminated by copying the
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* data here directly into mbufs and passing the mbuf chain
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* down. But that will require a fair amount of re-working
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* of the code and can be done if there's enough interest
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* in NFS directio access.
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*/
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while (uiop->uio_resid > 0) {
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size = min(uiop->uio_resid, nmp->nm_wsize);
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size = min(uiop->uio_iov->iov_len, size);
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bp = getpbuf(&nfs_pbuf_freecnt);
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t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
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t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
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t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
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t_iov->iov_len = size;
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t_uio->uio_iov = t_iov;
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t_uio->uio_iovcnt = 1;
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t_uio->uio_offset = uiop->uio_offset;
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t_uio->uio_resid = size;
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t_uio->uio_segflg = UIO_SYSSPACE;
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t_uio->uio_rw = UIO_WRITE;
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t_uio->uio_td = td;
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bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
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bp->b_flags |= B_DIRECT;
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bp->b_iocmd = BIO_WRITE;
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if (cred != NOCRED) {
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crhold(cred);
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bp->b_wcred = cred;
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} else
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bp->b_wcred = NOCRED;
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bp->b_caller1 = (void *)t_uio;
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bp->b_vp = vp;
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vhold(vp);
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error = nfs_asyncio(nmp, bp, NOCRED, td);
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if (error) {
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free(t_iov->iov_base, M_NFSDIRECTIO);
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free(t_iov, M_NFSDIRECTIO);
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free(t_uio, M_NFSDIRECTIO);
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vdrop(bp->b_vp);
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bp->b_vp = NULL;
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relpbuf(bp, &nfs_pbuf_freecnt);
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if (error == EINTR)
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return (error);
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goto do_sync;
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}
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uiop->uio_offset += size;
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uiop->uio_resid -= size;
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if (uiop->uio_iov->iov_len <= size) {
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uiop->uio_iovcnt--;
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uiop->uio_iov++;
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} else {
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uiop->uio_iov->iov_base =
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(char *)uiop->uio_iov->iov_base + size;
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uiop->uio_iov->iov_len -= size;
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}
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}
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}
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return (0);
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}
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/*
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* Vnode op for write using bio
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*/
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@ -756,6 +907,9 @@ nfs_write(struct vop_write_args *ap)
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if (uio->uio_resid == 0)
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return (0);
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if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
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return nfs_directio_write(vp, uio, cred, ioflag);
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/*
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* We need to obtain the rslock if we intend to modify np->n_size
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* in order to guarentee the append point with multiple contending
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@ -1261,6 +1415,26 @@ nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thr
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return (EIO);
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}
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void
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nfs_doio_directwrite(struct buf *bp)
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{
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int iomode, must_commit;
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struct uio *uiop = (struct uio *)bp->b_caller1;
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char *iov_base = uiop->uio_iov->iov_base;
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struct nfsmount *nmp = VFSTONFS(bp->b_vp->v_mount);
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iomode = NFSV3WRITE_FILESYNC;
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uiop->uio_td = NULL; /* NULL since we're in nfsiod */
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(nmp->nm_rpcops->nr_writerpc)(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
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KASSERT((must_commit == 0), ("nfs_doio_directwrite: Did not commit write"));
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free(iov_base, M_NFSDIRECTIO);
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free(uiop->uio_iov, M_NFSDIRECTIO);
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free(uiop, M_NFSDIRECTIO);
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vdrop(bp->b_vp);
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bp->b_vp = NULL;
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relpbuf(bp, &nfs_pbuf_freecnt);
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}
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/*
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* Do an I/O operation to/from a cache block. This may be called
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* synchronously or from an nfsiod.
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@ -243,10 +243,16 @@ nfssvc_iod(void *instance)
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nmp->nm_bufqwant = 0;
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wakeup(&nmp->nm_bufq);
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}
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if (bp->b_iocmd == BIO_READ)
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(void) nfs_doio(bp->b_vp, bp, bp->b_rcred, NULL);
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else
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(void) nfs_doio(bp->b_vp, bp, bp->b_wcred, NULL);
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if (bp->b_flags & B_DIRECT) {
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KASSERT((bp->b_iocmd == BIO_WRITE), ("nfscvs_iod: BIO_WRITE not set"));
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(void)nfs_doio_directwrite(bp);
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} else {
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if (bp->b_iocmd == BIO_READ)
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(void) nfs_doio(bp->b_vp, bp, bp->b_rcred, NULL);
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else
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(void) nfs_doio(bp->b_vp, bp, bp->b_wcred, NULL);
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}
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/*
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* If there are more than one iod on this mount, then defect
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* so that the iods can be shared out fairly between the mounts
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@ -78,6 +78,7 @@ MALLOC_DEFINE(M_NFSREQ, "NFS req", "NFS request header");
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MALLOC_DEFINE(M_NFSBIGFH, "NFSV3 bigfh", "NFS version 3 file handle");
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MALLOC_DEFINE(M_NFSDIROFF, "NFSV3 diroff", "NFS directory offset data");
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MALLOC_DEFINE(M_NFSHASH, "NFS hash", "NFS hash tables");
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MALLOC_DEFINE(M_NFSDIRECTIO, "NFS DirectIO", "NFS Direct IO async write state");
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uma_zone_t nfsmount_zone;
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@ -211,6 +211,24 @@ static int nfs_clean_pages_on_close = 1;
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SYSCTL_INT(_vfs_nfs, OID_AUTO, clean_pages_on_close, CTLFLAG_RW,
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&nfs_clean_pages_on_close, 0, "NFS clean dirty pages on close");
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int nfs_directio_enable = 1;
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SYSCTL_INT(_vfs_nfs, OID_AUTO, nfs_directio_enable, CTLFLAG_RW,
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&nfs_directio_enable, 0, "Enable NFS directio");
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/*
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* This sysctl allows other processes to mmap a file that has been opened O_DIRECT
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* by a process. In general, having processes mmap the file while Direct IO is in
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* progress can lead to Data Inconsistencies. But, we allow this by default to
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* prevent DoS attacks - to prevent a malicious user from opening up files O_DIRECT
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* preventing other users from mmap'ing these files. "Protected" environments where
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* stricter consistency guarantees are required can disable this knob.
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* The process that opened the file O_DIRECT cannot mmap() the file, because
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* mmap'ed IO on an O_DIRECT open() is not meaningful.
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*/
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int nfs_directio_allow_mmap = 1;
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SYSCTL_INT(_vfs_nfs, OID_AUTO, nfs_directio_allow_mmap, CTLFLAG_RW,
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&nfs_directio_allow_mmap, 0, "Enable mmaped IO on file with O_DIRECT opens");
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#if 0
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SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_hits, CTLFLAG_RD,
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&nfsstats.accesscache_hits, 0, "NFS ACCESS cache hit count");
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@ -401,6 +419,7 @@ nfs_open(struct vop_open_args *ap)
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struct nfsnode *np = VTONFS(vp);
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struct vattr vattr;
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int error;
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int fmode = ap->a_mode;
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if (vp->v_type != VREG && vp->v_type != VDIR && vp->v_type != VLNK)
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return (EOPNOTSUPP);
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@ -434,6 +453,18 @@ nfs_open(struct vop_open_args *ap)
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np->n_mtime = vattr.va_mtime;
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}
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}
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/*
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* If the object has >= 1 O_DIRECT active opens, we disable caching.
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*/
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if (nfs_directio_enable && (fmode & O_DIRECT) && (vp->v_type == VREG)) {
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if (np->n_directio_opens == 0) {
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error = nfs_vinvalbuf(vp, V_SAVE, ap->a_cred, ap->a_td, 1);
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if (error)
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return (error);
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np->n_flag |= NNONCACHE;
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}
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np->n_directio_opens++;
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}
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np->ra_expect_lbn = 0;
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return (0);
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}
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@ -472,6 +503,7 @@ nfs_close(struct vop_close_args *ap)
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struct vnode *vp = ap->a_vp;
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struct nfsnode *np = VTONFS(vp);
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int error = 0;
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int fmode = ap->a_fflag;
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if (vp->v_type == VREG) {
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/*
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@ -520,6 +552,13 @@ nfs_close(struct vop_close_args *ap)
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error = np->n_error;
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}
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}
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if (nfs_directio_enable && (fmode & O_DIRECT) && (vp->v_type == VREG)) {
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KASSERT((np->n_directio_opens > 0),
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("nfs_close: unexpectedly value (0) of n_directio_opens\n"));
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np->n_directio_opens--;
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if (np->n_directio_opens == 0)
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np->n_flag &= ~NNONCACHE;
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}
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return (error);
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}
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@ -127,6 +127,7 @@ struct nfsnode {
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u_char *n_name; /* leaf name, for v4 OPEN op */
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uint32_t n_namelen;
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daddr_t ra_expect_lbn;
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int n_directio_opens;
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};
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#define n_atim n_un1.nf_atim
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@ -149,6 +150,7 @@ struct nfsnode {
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#define NCREATED 0x0800 /* Opened by nfs_create() */
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#define NTRUNCATE 0x1000 /* Opened by nfs_setattr() */
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#define NSIZECHANGED 0x2000 /* File size has changed: need cache inval */
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#define NNONCACHE 0x4000 /* Node marked as noncacheable */
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/*
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* Convert between nfsnode pointers and vnode pointers
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