Re: [PATCH v6 06/18] nfs/nfsd: add "localio" support

NeilBrown
2024-06-21T06:08:29Z

On Thu, 20 Jun 2024, Mike Snitzer wrote:
> From: Weston Andros Adamson <dros@primarydata.com>
>
> Add client support for bypassing NFS for localhost reads, writes, and
> commits. This is only useful when the client and the server are
> running on the same host.
>
> nfs_local_probe() is stubbed out, later commits will enable client and
> server handshake via a Linux-only LOCALIO auxiliary RPC protocol.
>
> This has dynamic binding with the nfsd module (via nfs_localio module
> which is part of nfs_common). Localio will only work if nfsd is
> already loaded.
>
> The "localio_enabled" nfs kernel module parameter can be used to
> disable and enable the ability to use localio support.
>
> Tracepoints were added for nfs_local_open_fh, nfs_local_enable and
> nfs_local_disable.
>
> Also, pass the stored cl_nfssvc_net from the client to the server as
> first argument to nfsd_open_local_fh() to ensure the proper network
> namespace is used for localio.
>
> Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
> Signed-off-by: Peng Tao <tao.peng@primarydata.com>
> Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
> ---
> fs/nfs/Makefile | 1 +
> fs/nfs/client.c | 3 +
> fs/nfs/inode.c | 4 +
> fs/nfs/internal.h | 51 +++
> fs/nfs/localio.c | 722 ++++++++++++++++++++++++++++++++++++++
> fs/nfs/nfstrace.h | 61 ++++
> fs/nfs/pagelist.c | 3 +
> fs/nfs/write.c | 3 +
> fs/nfsd/Makefile | 1 +
> fs/nfsd/filecache.c | 2 +-
> fs/nfsd/localio.c | 244 +++++++++++++
> fs/nfsd/nfssvc.c | 1 +
> fs/nfsd/trace.h | 3 +-
> fs/nfsd/vfs.h | 9 +
> include/linux/nfs.h | 2 +
> include/linux/nfs_fs.h | 2 +
> include/linux/nfs_fs_sb.h | 1 +
> include/linux/nfs_xdr.h | 1 +
> 18 files changed, 1112 insertions(+), 2 deletions(-)
> create mode 100644 fs/nfs/localio.c
> create mode 100644 fs/nfsd/localio.c
>
> diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
> index 5f6db37f461e..9fb2f2cac87e 100644
> --- a/fs/nfs/Makefile
> +++ b/fs/nfs/Makefile
> @@ -13,6 +13,7 @@ nfs-y := client.o dir.o file.o getroot.o inode.o super.o \
> nfs-$(CONFIG_ROOT_NFS) += nfsroot.o
> nfs-$(CONFIG_SYSCTL) += sysctl.o
> nfs-$(CONFIG_NFS_FSCACHE) += fscache.o
> +nfs-$(CONFIG_NFS_LOCALIO) += localio.o
>
> obj-$(CONFIG_NFS_V2) += nfsv2.o
> nfsv2-y := nfs2super.o proc.o nfs2xdr.o
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index bcdf8d42cbc7..1300c388f971 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -241,6 +241,8 @@ static void pnfs_init_server(struct nfs_server *server)
> */
> void nfs_free_client(struct nfs_client *clp)
> {
> + nfs_local_disable(clp);
> +
> /* -EIO all pending I/O */
> if (!IS_ERR(clp->cl_rpcclient))
> rpc_shutdown_client(clp->cl_rpcclient);
> @@ -432,6 +434,7 @@ struct nfs_client *nfs_get_client(const struct nfs_client_initdata *cl_init)
> list_add_tail(&new->cl_share_link,
> &nn->nfs_client_list);
> spin_unlock(&nn->nfs_client_lock);
> + nfs_local_probe(new);
> return rpc_ops->init_client(new, cl_init);
> }
>
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index acef52ecb1bb..f9923cbf6058 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -39,6 +39,7 @@
> #include <linux/slab.h>
> #include <linux/compat.h>
> #include <linux/freezer.h>
> +#include <linux/file.h>
> #include <linux/uaccess.h>
> #include <linux/iversion.h>
>
> @@ -1053,6 +1054,7 @@ struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry,
> ctx->lock_context.open_context = ctx;
> INIT_LIST_HEAD(&ctx->list);
> ctx->mdsthreshold = NULL;
> + ctx->local_filp = NULL;
> return ctx;
> }
> EXPORT_SYMBOL_GPL(alloc_nfs_open_context);
> @@ -1084,6 +1086,8 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)
> nfs_sb_deactive(sb);
> put_rpccred(rcu_dereference_protected(ctx->ll_cred, 1));
> kfree(ctx->mdsthreshold);
> + if (!IS_ERR_OR_NULL(ctx->local_filp))
> + fput(ctx->local_filp);
> kfree_rcu(ctx, rcu_head);
> }
>
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index 958c8de072e2..d352040e3232 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -451,6 +451,57 @@ extern void nfs_set_cache_invalid(struct inode *inode, unsigned long flags);
> extern bool nfs_check_cache_invalid(struct inode *, unsigned long);
> extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
>
> +#if IS_ENABLED(CONFIG_NFS_LOCALIO)
> +/* localio.c */
> +extern void nfs_local_disable(struct nfs_client *);
> +extern void nfs_local_probe(struct nfs_client *);
> +extern struct file *nfs_local_open_fh(struct nfs_client *, const struct cred *,
> + struct nfs_fh *, const fmode_t);
> +extern struct file *nfs_local_file_open(struct nfs_client *clp,
> + const struct cred *cred,
> + struct nfs_fh *fh,
> + struct nfs_open_context *ctx);
> +extern int nfs_local_doio(struct nfs_client *, struct file *,
> + struct nfs_pgio_header *,
> + const struct rpc_call_ops *);
> +extern int nfs_local_commit(struct file *, struct nfs_commit_data *,
> + const struct rpc_call_ops *, int);
> +extern bool nfs_server_is_local(const struct nfs_client *clp);
> +
> +#else
> +static inline void nfs_local_disable(struct nfs_client *clp) {}
> +static inline void nfs_local_probe(struct nfs_client *clp) {}
> +static inline struct file *nfs_local_open_fh(struct nfs_client *clp,
> + const struct cred *cred,
> + struct nfs_fh *fh,
> + const fmode_t mode)
> +{
> + return ERR_PTR(-EINVAL);
> +}
> +static inline struct file *nfs_local_file_open(struct nfs_client *clp,
> + const struct cred *cred,
> + struct nfs_fh *fh,
> + struct nfs_open_context *ctx)
> +{
> + return NULL;
> +}
> +static inline int nfs_local_doio(struct nfs_client *clp, struct file *filep,
> + struct nfs_pgio_header *hdr,
> + const struct rpc_call_ops *call_ops)
> +{
> + return -EINVAL;
> +}
> +static inline int nfs_local_commit(struct file *filep, struct nfs_commit_data *data,
> + const struct rpc_call_ops *call_ops, int how)
> +{
> + return -EINVAL;
> +}
> +static inline bool nfs_server_is_local(const struct nfs_client *clp)
> +{
> + return false;
> +}
> +#endif /* CONFIG_NFS_LOCALIO */
> +
> /* super.c */
> extern const struct super_operations nfs_sops;
> bool nfs_auth_info_match(const struct nfs_auth_info *, rpc_authflavor_t);
> diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
> new file mode 100644
> index 000000000000..38d0832442b2
> --- /dev/null
> +++ b/fs/nfs/localio.c
> @@ -0,0 +1,722 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * NFS client support for local clients to bypass network stack
> + *
> + * Copyright (C) 2014 Weston Andros Adamson <dros@primarydata.com>
> + * Copyright (C) 2019 Trond Myklebust <trond.myklebust@hammerspace.com>
> + * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/errno.h>
> +#include <linux/vfs.h>
> +#include <linux/file.h>
> +#include <linux/inet.h>
> +#include <linux/sunrpc/addr.h>
> +#include <linux/inetdevice.h>
> +#include <net/addrconf.h>
> +#include <linux/module.h>
> +#include <linux/bvec.h>
> +
> +#include <linux/nfs.h>
> +#include <linux/nfs_fs.h>
> +#include <linux/nfs_xdr.h>
> +
> +#include "internal.h"
> +#include "pnfs.h"
> +#include "nfstrace.h"
> +
> +#define NFSDBG_FACILITY NFSDBG_VFS
> +
> +struct nfs_local_kiocb {
> + struct kiocb kiocb;
> + struct bio_vec *bvec;
> + struct nfs_pgio_header *hdr;
> + struct work_struct work;
> +};
> +
> +struct nfs_local_fsync_ctx {
> + struct file *filp;
> + struct nfs_commit_data *data;
> + struct work_struct work;
> + struct kref kref;
> + struct completion *done;
> +};
> +static void nfs_local_fsync_work(struct work_struct *work);
> +
> +/*
> + * We need to translate between nfs status return values and
> + * the local errno values which may not be the same.
> + */
> +static struct {
> + __u32 stat;
> + int errno;
> +} nfs_errtbl[] = {
> + { NFS4_OK, 0 },
> + { NFS4ERR_PERM, -EPERM },
> + { NFS4ERR_NOENT, -ENOENT },
> + { NFS4ERR_IO, -EIO },
> + { NFS4ERR_NXIO, -ENXIO },
> + { NFS4ERR_FBIG, -E2BIG },
> + { NFS4ERR_STALE, -EBADF },
> + { NFS4ERR_ACCESS, -EACCES },
> + { NFS4ERR_EXIST, -EEXIST },
> + { NFS4ERR_XDEV, -EXDEV },
> + { NFS4ERR_MLINK, -EMLINK },
> + { NFS4ERR_NOTDIR, -ENOTDIR },
> + { NFS4ERR_ISDIR, -EISDIR },
> + { NFS4ERR_INVAL, -EINVAL },
> + { NFS4ERR_FBIG, -EFBIG },
> + { NFS4ERR_NOSPC, -ENOSPC },
> + { NFS4ERR_ROFS, -EROFS },
> + { NFS4ERR_NAMETOOLONG, -ENAMETOOLONG },
> + { NFS4ERR_NOTEMPTY, -ENOTEMPTY },
> + { NFS4ERR_DQUOT, -EDQUOT },
> + { NFS4ERR_STALE, -ESTALE },
> + { NFS4ERR_STALE, -EOPENSTALE },
> + { NFS4ERR_DELAY, -ETIMEDOUT },
> + { NFS4ERR_DELAY, -ERESTARTSYS },
> + { NFS4ERR_DELAY, -EAGAIN },
> + { NFS4ERR_DELAY, -ENOMEM },
> + { NFS4ERR_IO, -ETXTBSY },
> + { NFS4ERR_IO, -EBUSY },
> + { NFS4ERR_BADHANDLE, -EBADHANDLE },
> + { NFS4ERR_BAD_COOKIE, -EBADCOOKIE },
> + { NFS4ERR_NOTSUPP, -EOPNOTSUPP },
> + { NFS4ERR_TOOSMALL, -ETOOSMALL },
> + { NFS4ERR_SERVERFAULT, -ESERVERFAULT },
> + { NFS4ERR_SERVERFAULT, -ENFILE },
> + { NFS4ERR_IO, -EREMOTEIO },
> + { NFS4ERR_IO, -EUCLEAN },
> + { NFS4ERR_PERM, -ENOKEY },
> + { NFS4ERR_BADTYPE, -EBADTYPE },
> + { NFS4ERR_SYMLINK, -ELOOP },
> + { NFS4ERR_DEADLOCK, -EDEADLK },
> +};
> +
> +/*
> + * Convert an NFS error code to a local one.
> + * This one is used jointly by NFSv2 and NFSv3.
> + */
> +static __u32
> +nfs4errno(int errno)
> +{
> + unsigned int i;
> + for (i = 0; i < ARRAY_SIZE(nfs_errtbl); i++) {
> + if (nfs_errtbl[i].errno == errno)
> + return nfs_errtbl[i].stat;
> + }
> + /* If we cannot translate the error, the recovery routines should
> + * handle it.
> + * Note: remaining NFSv4 error codes have values > 10000, so should
> + * not conflict with native Linux error codes.
> + */
> + return NFS4ERR_SERVERFAULT;
> +}
> +
> +static bool localio_enabled __read_mostly = true;
> +module_param(localio_enabled, bool, 0644);
> +
> +bool nfs_server_is_local(const struct nfs_client *clp)
> +{
> + return test_bit(NFS_CS_LOCAL_IO, &clp->cl_flags) != 0 &&
> + localio_enabled;
> +}
> +EXPORT_SYMBOL_GPL(nfs_server_is_local);
> +
> +/*
> + * nfs_local_enable - attempt to enable local i/o for an nfs_client
> + */
> +static void nfs_local_enable(struct nfs_client *clp, struct net *net)
> +{
> + if (READ_ONCE(clp->nfsd_open_local_fh)) {
> + set_bit(NFS_CS_LOCAL_IO, &clp->cl_flags);
> + clp->cl_nfssvc_net = net;
> + trace_nfs_local_enable(clp);
> + }
> +}
> +
> +/*
> + * nfs_local_disable - disable local i/o for an nfs_client
> + */
> +void nfs_local_disable(struct nfs_client *clp)
> +{
> + if (test_and_clear_bit(NFS_CS_LOCAL_IO, &clp->cl_flags)) {
> + trace_nfs_local_disable(clp);
> + clp->cl_nfssvc_net = NULL;
> + }
> +}
> +
> +/*
> + * nfs_local_probe - probe local i/o support for an nfs_client
> + */
> +void
> +nfs_local_probe(struct nfs_client *clp)
> +{
> + bool enable = false;
> +
> + if (enable)
> + nfs_local_enable(clp);
> +}
> +EXPORT_SYMBOL_GPL(nfs_local_probe);
> +
> +/*
> + * nfs_local_open_fh - open a local filehandle
> + *
> + * Returns a pointer to a struct file or an ERR_PTR
> + */
> +struct file *
> +nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
> + struct nfs_fh *fh, const fmode_t mode)
> +{
> + struct file *filp;
> + int status;
> +
> + if (mode & ~(FMODE_READ | FMODE_WRITE))
> + return ERR_PTR(-EINVAL);
> +
> + status = clp->nfsd_open_local_fh(clp->cl_nfssvc_net, clp->cl_rpcclient,
> + cred, fh, mode, &filp);
> + if (status < 0) {
> + dprintk("%s: open local file failed error=%d\n",
> + __func__, status);
> + trace_nfs_local_open_fh(fh, mode, status);
> + switch (status) {
> + case -ENXIO:
> + nfs_local_disable(clp);
> + fallthrough;
> + case -ETIMEDOUT:
> + status = -EAGAIN;
> + }
> + filp = ERR_PTR(status);
> + }
> + return filp;
> +}
> +EXPORT_SYMBOL_GPL(nfs_local_open_fh);
> +
> +static struct bio_vec *
> +nfs_bvec_alloc_and_import_pagevec(struct page **pagevec,
> + unsigned int npages, gfp_t flags)
> +{
> + struct bio_vec *bvec, *p;
> +
> + bvec = kmalloc_array(npages, sizeof(*bvec), flags);
> + if (bvec != NULL) {
> + for (p = bvec; npages > 0; p++, pagevec++, npages--) {
> + p->bv_page = *pagevec;
> + p->bv_len = PAGE_SIZE;
> + p->bv_offset = 0;
> + }
> + }
> + return bvec;
> +}
> +
> +static void
> +nfs_local_iocb_free(struct nfs_local_kiocb *iocb)
> +{
> + kfree(iocb->bvec);
> + kfree(iocb);
> +}
> +
> +static struct nfs_local_kiocb *
> +nfs_local_iocb_alloc(struct nfs_pgio_header *hdr, struct file *filp,
> + gfp_t flags)
> +{
> + struct nfs_local_kiocb *iocb;
> +
> + iocb = kmalloc(sizeof(*iocb), flags);
> + if (iocb == NULL)
> + return NULL;
> + iocb->bvec = nfs_bvec_alloc_and_import_pagevec(hdr->page_array.pagevec,
> + hdr->page_array.npages, flags);
> + if (iocb->bvec == NULL) {
> + kfree(iocb);
> + return NULL;
> + }
> + init_sync_kiocb(&iocb->kiocb, filp);
> + iocb->kiocb.ki_pos = hdr->args.offset;
> + iocb->hdr = hdr;
> + /* FIXME: NFS_IOHDR_ODIRECT isn't ever set */
> + if (test_bit(NFS_IOHDR_ODIRECT, &hdr->flags))
> + iocb->kiocb.ki_flags |= IOCB_DIRECT|IOCB_DSYNC;
> + iocb->kiocb.ki_flags &= ~IOCB_APPEND;
> + return iocb;
> +}
> +
> +static void
> +nfs_local_iter_init(struct iov_iter *i, struct nfs_local_kiocb *iocb, int dir)
> +{
> + struct nfs_pgio_header *hdr = iocb->hdr;
> +
> + if (hdr->args.pgbase != 0) {
> + iov_iter_bvec(i, dir, iocb->bvec,
> + hdr->page_array.npages,
> + hdr->args.count + hdr->args.pgbase);
> + iov_iter_advance(i, hdr->args.pgbase);
> + } else
> + iov_iter_bvec(i, dir, iocb->bvec,
> + hdr->page_array.npages, hdr->args.count);

Both branches of this if() do exactly the same thing. iov_iter_advance
is a no-op if the size arg is zero.

Is it really worth increasing the code size to sometimes avoid a
function call?

At least we should for the iov_iter_bvec() inconditionally, then maybe
call _advance().

> +}
> +
> +static void
> +nfs_local_hdr_release(struct nfs_pgio_header *hdr,
> + const struct rpc_call_ops *call_ops)
> +{
> + call_ops->rpc_call_done(&hdr->task, hdr);
> + call_ops->rpc_release(hdr);
> +}
> +
> +static void
> +nfs_local_pgio_init(struct nfs_pgio_header *hdr,
> + const struct rpc_call_ops *call_ops)
> +{
> + hdr->task.tk_ops = call_ops;
> + if (!hdr->task.tk_start)
> + hdr->task.tk_start = ktime_get();
> +}
> +
> +static void
> +nfs_local_pgio_done(struct nfs_pgio_header *hdr, long status)
> +{
> + if (status >= 0) {
> + hdr->res.count = status;
> + hdr->res.op_status = NFS4_OK;
> + hdr->task.tk_status = 0;
> + } else {
> + hdr->res.op_status = nfs4errno(status);
> + hdr->task.tk_status = status;
> + }
> +}
> +
> +static void
> +nfs_local_pgio_release(struct nfs_local_kiocb *iocb)
> +{
> + struct nfs_pgio_header *hdr = iocb->hdr;
> +
> + fput(iocb->kiocb.ki_filp);
> + nfs_local_iocb_free(iocb);
> + nfs_local_hdr_release(hdr, hdr->task.tk_ops);
> +}
> +
> +static void
> +nfs_local_read_aio_complete_work(struct work_struct *work)
> +{
> + struct nfs_local_kiocb *iocb = container_of(work,
> + struct nfs_local_kiocb, work);
> +
> + nfs_local_pgio_release(iocb);
> +}
> +
> +/*
> + * Complete the I/O from iocb->kiocb.ki_complete()
> + *
> + * Note that this function can be called from a bottom half context,
> + * hence we need to queue the fput() etc to a workqueue

fput() is not a good excuse for a workqueue - the work is always
deferred either to a workqueue or to a process return-from-syscall
context.
However the ->rpc_call_done() and vfs_fsync_range() calls are excellent
justification for a workqueue.
So I think the comment should be improved, but the code looks sensible.

> + */
> +static void
> +nfs_local_pgio_complete(struct nfs_local_kiocb *iocb)
> +{
> + queue_work(nfsiod_workqueue, &iocb->work);
> +}
> +
> +static void
> +nfs_local_read_done(struct nfs_local_kiocb *iocb, long status)
> +{
> + struct nfs_pgio_header *hdr = iocb->hdr;
> + struct file *filp = iocb->kiocb.ki_filp;
> +
> + nfs_local_pgio_done(hdr, status);
> +
> + if (hdr->res.count != hdr->args.count ||
> + hdr->args.offset + hdr->res.count >= i_size_read(file_inode(filp)))
> + hdr->res.eof = true;
> +
> + dprintk("%s: read %ld bytes eof %d.\n", __func__,
> + status > 0 ? status : 0, hdr->res.eof);
> +}
> +
> +static void
> +nfs_local_read_aio_complete(struct kiocb *kiocb, long ret)
> +{
> + struct nfs_local_kiocb *iocb = container_of(kiocb,
> + struct nfs_local_kiocb, kiocb);
> +
> + nfs_local_read_done(iocb, ret);
> + nfs_local_pgio_complete(iocb);
> +}
> +
> +static int
> +nfs_do_local_read(struct nfs_pgio_header *hdr, struct file *filp,
> + const struct rpc_call_ops *call_ops)
> +{
> + struct nfs_local_kiocb *iocb;
> + struct iov_iter iter;
> + ssize_t status;
> +
> + dprintk("%s: vfs_read count=%u pos=%llu\n",
> + __func__, hdr->args.count, hdr->args.offset);
> +
> + iocb = nfs_local_iocb_alloc(hdr, filp, GFP_KERNEL);
> + if (iocb == NULL)
> + return -ENOMEM;
> + nfs_local_iter_init(&iter, iocb, READ);
> +
> + nfs_local_pgio_init(hdr, call_ops);
> + hdr->res.eof = false;
> +
> + if (iocb->kiocb.ki_flags & IOCB_DIRECT) {
> + INIT_WORK(&iocb->work, nfs_local_read_aio_complete_work);
> + iocb->kiocb.ki_complete = nfs_local_read_aio_complete;
> + }
> +
> + status = filp->f_op->read_iter(&iocb->kiocb, &iter);
> + if (status != -EIOCBQUEUED) {
> + nfs_local_read_done(iocb, status);
> + nfs_local_pgio_release(iocb);
> + }
> + return 0;
> +}
> +
> +static void
> +nfs_copy_boot_verifier(struct nfs_write_verifier *verifier, struct inode *inode)
> +{
> + struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
> + u32 *verf = (u32 *)verifier->data;
> + int seq = 0;
> +
> + do {
> + read_seqbegin_or_lock(&clp->cl_boot_lock, &seq);
> + verf[0] = (u32)clp->cl_nfssvc_boot.tv_sec;
> + verf[1] = (u32)clp->cl_nfssvc_boot.tv_nsec;
> + } while (need_seqretry(&clp->cl_boot_lock, seq));
> + done_seqretry(&clp->cl_boot_lock, seq);
> +}
> +
> +static void
> +nfs_reset_boot_verifier(struct inode *inode)
> +{
> + struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
> +
> + write_seqlock(&clp->cl_boot_lock);
> + ktime_get_real_ts64(&clp->cl_nfssvc_boot);
> + write_sequnlock(&clp->cl_boot_lock);
> +}
> +
> +static void
> +nfs_set_local_verifier(struct inode *inode,
> + struct nfs_writeverf *verf,
> + enum nfs3_stable_how how)
> +{
> +
> + nfs_copy_boot_verifier(&verf->verifier, inode);
> + verf->committed = how;
> +}
> +
> +static void
> +nfs_get_vfs_attr(struct file *filp, struct nfs_fattr *fattr)
> +{
> + struct kstat stat;
> +
> + if (fattr != NULL && vfs_getattr(&filp->f_path, &stat,
> + STATX_INO |
> + STATX_ATIME |
> + STATX_MTIME |
> + STATX_CTIME |
> + STATX_SIZE |
> + STATX_BLOCKS,
> + AT_STATX_SYNC_AS_STAT) == 0) {
> + fattr->valid = NFS_ATTR_FATTR_FILEID |
> + NFS_ATTR_FATTR_CHANGE |
> + NFS_ATTR_FATTR_SIZE |
> + NFS_ATTR_FATTR_ATIME |
> + NFS_ATTR_FATTR_MTIME |
> + NFS_ATTR_FATTR_CTIME |
> + NFS_ATTR_FATTR_SPACE_USED;
> + fattr->fileid = stat.ino;
> + fattr->size = stat.size;
> + fattr->atime = stat.atime;
> + fattr->mtime = stat.mtime;
> + fattr->ctime = stat.ctime;
> + fattr->change_attr = nfs_timespec_to_change_attr(&fattr->ctime);

This looks wrong for NFSv4. I think we should use
nfsd4_change_attribute().
Maybe it isn't important, but if it isn't I'd like to see an explanation
why.

> + fattr->du.nfs3.used = stat.blocks << 9;
> + }
> +}
> +
> +static void
> +nfs_local_write_done(struct nfs_local_kiocb *iocb, long status)
> +{
> + struct nfs_pgio_header *hdr = iocb->hdr;
> +
> + dprintk("%s: wrote %ld bytes.\n", __func__, status > 0 ? status : 0);
> +
> + /* Handle short writes as if they are ENOSPC */
> + if (status > 0 && status < hdr->args.count) {
> + hdr->mds_offset += status;
> + hdr->args.offset += status;
> + hdr->args.pgbase += status;
> + hdr->args.count -= status;
> + nfs_set_pgio_error(hdr, -ENOSPC, hdr->args.offset);
> + status = -ENOSPC;
> + }
> + if (status < 0)
> + nfs_reset_boot_verifier(hdr->inode);
> + nfs_local_pgio_done(hdr, status);
> +}
> +
> +static void
> +nfs_local_write_aio_complete_work(struct work_struct *work)
> +{
> + struct nfs_local_kiocb *iocb = container_of(work,
> + struct nfs_local_kiocb, work);
> +
> + nfs_get_vfs_attr(iocb->kiocb.ki_filp, iocb->hdr->res.fattr);
> + nfs_local_pgio_release(iocb);
> +}
> +
> +static void
> +nfs_local_write_aio_complete(struct kiocb *kiocb, long ret)
> +{
> + struct nfs_local_kiocb *iocb = container_of(kiocb,
> + struct nfs_local_kiocb, kiocb);
> +
> + nfs_local_write_done(iocb, ret);
> + nfs_local_pgio_complete(iocb);
> +}
> +
> +static int
> +nfs_do_local_write(struct nfs_pgio_header *hdr, struct file *filp,
> + const struct rpc_call_ops *call_ops)
> +{
> + struct nfs_local_kiocb *iocb;
> + struct iov_iter iter;
> + ssize_t status;
> +
> + dprintk("%s: vfs_write count=%u pos=%llu %s\n",
> + __func__, hdr->args.count, hdr->args.offset,
> + (hdr->args.stable == NFS_UNSTABLE) ? "unstable" : "stable");
> +
> + iocb = nfs_local_iocb_alloc(hdr, filp, GFP_NOIO);
> + if (iocb == NULL)
> + return -ENOMEM;
> + nfs_local_iter_init(&iter, iocb, WRITE);
> +
> + switch (hdr->args.stable) {
> + default:
> + break;
> + case NFS_DATA_SYNC:
> + iocb->kiocb.ki_flags |= IOCB_DSYNC;
> + break;
> + case NFS_FILE_SYNC:
> + iocb->kiocb.ki_flags |= IOCB_DSYNC|IOCB_SYNC;
> + }
> + nfs_local_pgio_init(hdr, call_ops);
> +
> + if (iocb->kiocb.ki_flags & IOCB_DIRECT) {
> + INIT_WORK(&iocb->work, nfs_local_write_aio_complete_work);
> + iocb->kiocb.ki_complete = nfs_local_write_aio_complete;
> + }
> +
> + nfs_set_local_verifier(hdr->inode, hdr->res.verf, hdr->args.stable);
> +
> + file_start_write(filp);
> + status = filp->f_op->write_iter(&iocb->kiocb, &iter);
> + file_end_write(filp);
> + if (status != -EIOCBQUEUED) {
> + nfs_local_write_done(iocb, status);
> + nfs_get_vfs_attr(filp, hdr->res.fattr);
> + nfs_local_pgio_release(iocb);
> + }
> + return 0;
> +}
> +
> +static struct file *
> +nfs_local_file_open_cached(struct nfs_client *clp, const struct cred *cred,
> + struct nfs_fh *fh, struct nfs_open_context *ctx)
> +{
> + struct file *filp = ctx->local_filp;
> +
> + if (!filp) {
> + struct file *new = nfs_local_open_fh(clp, cred, fh, ctx->mode);
> + if (IS_ERR_OR_NULL(new))
> + return NULL;
> + /* try to put this one in the slot */
> + filp = cmpxchg(&ctx->local_filp, NULL, new);
> + if (filp != NULL)
> + fput(new);
> + else
> + filp = new;
> + }
> + return get_file(filp);
> +}
> +
> +struct file *
> +nfs_local_file_open(struct nfs_client *clp, const struct cred *cred,
> + struct nfs_fh *fh, struct nfs_open_context *ctx)
> +{
> + if (!nfs_server_is_local(clp))
> + return NULL;
> + return nfs_local_file_open_cached(clp, cred, fh, ctx);
> +}
> +
> +int
> +nfs_local_doio(struct nfs_client *clp, struct file *filp,
> + struct nfs_pgio_header *hdr,
> + const struct rpc_call_ops *call_ops)
> +{
> + int status = 0;
> +
> + if (!hdr->args.count)
> + goto out_fput;
> + /* Don't support filesystems without read_iter/write_iter */
> + if (!filp->f_op->read_iter || !filp->f_op->write_iter) {
> + nfs_local_disable(clp);
> + status = -EAGAIN;
> + goto out_fput;
> + }
> +
> + switch (hdr->rw_mode) {
> + case FMODE_READ:
> + status = nfs_do_local_read(hdr, filp, call_ops);
> + break;
> + case FMODE_WRITE:
> + status = nfs_do_local_write(hdr, filp, call_ops);
> + break;
> + default:
> + dprintk("%s: invalid mode: %d\n", __func__,
> + hdr->rw_mode);
> + status = -EINVAL;
> + }
> +out_fput:
> + if (status != 0) {
> + fput(filp);
> + hdr->task.tk_status = status;
> + nfs_local_hdr_release(hdr, call_ops);
> + }
> + return status;
> +}
> +
> +static void
> +nfs_local_init_commit(struct nfs_commit_data *data,
> + const struct rpc_call_ops *call_ops)
> +{
> + data->task.tk_ops = call_ops;
> +}
> +
> +static int
> +nfs_local_run_commit(struct file *filp, struct nfs_commit_data *data)
> +{
> + loff_t start = data->args.offset;
> + loff_t end = LLONG_MAX;
> +
> + if (data->args.count > 0) {
> + end = start + data->args.count - 1;
> + if (end < start)
> + end = LLONG_MAX;
> + }
> +
> + dprintk("%s: commit %llu - %llu\n", __func__, start, end);
> + return vfs_fsync_range(filp, start, end, 0);
> +}
> +
> +static void
> +nfs_local_commit_done(struct nfs_commit_data *data, int status)
> +{
> + if (status >= 0) {
> + nfs_set_local_verifier(data->inode,
> + data->res.verf,
> + NFS_FILE_SYNC);
> + data->res.op_status = NFS4_OK;
> + data->task.tk_status = 0;
> + } else {
> + nfs_reset_boot_verifier(data->inode);
> + data->res.op_status = nfs4errno(status);
> + data->task.tk_status = status;
> + }
> +}
> +
> +static void
> +nfs_local_release_commit_data(struct file *filp,
> + struct nfs_commit_data *data,
> + const struct rpc_call_ops *call_ops)
> +{
> + fput(filp);
> + call_ops->rpc_call_done(&data->task, data);
> + call_ops->rpc_release(data);
> +}
> +
> +static struct nfs_local_fsync_ctx *
> +nfs_local_fsync_ctx_alloc(struct nfs_commit_data *data, struct file *filp,
> + gfp_t flags)
> +{
> + struct nfs_local_fsync_ctx *ctx = kmalloc(sizeof(*ctx), flags);
> +
> + if (ctx != NULL) {
> + ctx->filp = filp;
> + ctx->data = data;
> + INIT_WORK(&ctx->work, nfs_local_fsync_work);
> + kref_init(&ctx->kref);
> + ctx->done = NULL;
> + }
> + return ctx;
> +}
> +
> +static void
> +nfs_local_fsync_ctx_kref_free(struct kref *kref)
> +{
> + kfree(container_of(kref, struct nfs_local_fsync_ctx, kref));
> +}
> +
> +static void
> +nfs_local_fsync_ctx_put(struct nfs_local_fsync_ctx *ctx)
> +{
> + kref_put(&ctx->kref, nfs_local_fsync_ctx_kref_free);
> +}
> +
> +static void
> +nfs_local_fsync_ctx_free(struct nfs_local_fsync_ctx *ctx)
> +{
> + nfs_local_release_commit_data(ctx->filp, ctx->data,
> + ctx->data->task.tk_ops);
> + nfs_local_fsync_ctx_put(ctx);
> +}
> +
> +static void
> +nfs_local_fsync_work(struct work_struct *work)
> +{
> + struct nfs_local_fsync_ctx *ctx;
> + int status;
> +
> + ctx = container_of(work, struct nfs_local_fsync_ctx, work);
> +
> + status = nfs_local_run_commit(ctx->filp, ctx->data);
> + nfs_local_commit_done(ctx->data, status);
> + if (ctx->done != NULL)
> + complete(ctx->done);
> + nfs_local_fsync_ctx_free(ctx);
> +}
> +
> +int
> +nfs_local_commit(struct file *filp, struct nfs_commit_data *data,
> + const struct rpc_call_ops *call_ops, int how)
> +{
> + struct nfs_local_fsync_ctx *ctx;
> +
> + ctx = nfs_local_fsync_ctx_alloc(data, filp, GFP_KERNEL);
> + if (!ctx) {
> + nfs_local_commit_done(data, -ENOMEM);
> + nfs_local_release_commit_data(filp, data, call_ops);
> + return -ENOMEM;
> + }
> +
> + nfs_local_init_commit(data, call_ops);
> + kref_get(&ctx->kref);
> + if (how & FLUSH_SYNC) {
> + DECLARE_COMPLETION_ONSTACK(done);
> + ctx->done = &done;
> + queue_work(nfsiod_workqueue, &ctx->work);
> + wait_for_completion(&done);
> + } else
> + queue_work(nfsiod_workqueue, &ctx->work);
> + nfs_local_fsync_ctx_put(ctx);
> + return 0;
> +}
> diff --git a/fs/nfs/nfstrace.h b/fs/nfs/nfstrace.h
> index 1e710654af11..95a2c19a9172 100644
> --- a/fs/nfs/nfstrace.h
> +++ b/fs/nfs/nfstrace.h
> @@ -1681,6 +1681,67 @@ TRACE_EVENT(nfs_mount_path,
> TP_printk("path='%s'", __get_str(path))
> );
>
> +TRACE_EVENT(nfs_local_open_fh,
> + TP_PROTO(
> + const struct nfs_fh *fh,
> + fmode_t fmode,
> + int error
> + ),
> +
> + TP_ARGS(fh, fmode, error),
> +
> + TP_STRUCT__entry(
> + __field(int, error)
> + __field(u32, fhandle)
> + __field(unsigned int, fmode)
> + ),
> +
> + TP_fast_assign(
> + __entry->error = error;
> + __entry->fhandle = nfs_fhandle_hash(fh);
> + __entry->fmode = (__force unsigned int)fmode;
> + ),
> +
> + TP_printk(
> + "error=%d fhandle=0x%08x mode=%s",
> + __entry->error,
> + __entry->fhandle,
> + show_fs_fmode_flags(__entry->fmode)
> + )
> +);
> +
> +DECLARE_EVENT_CLASS(nfs_local_client_event,
> + TP_PROTO(
> + const struct nfs_client *clp
> + ),
> +
> + TP_ARGS(clp),
> +
> + TP_STRUCT__entry(
> + __field(unsigned int, protocol)
> + __string(server, clp->cl_hostname)
> + ),
> +
> + TP_fast_assign(
> + __entry->protocol = clp->rpc_ops->version;
> + __assign_str(server);
> + ),
> +
> + TP_printk(
> + "server=%s NFSv%u", __get_str(server), __entry->protocol
> + )
> +);
> +
> +#define DEFINE_NFS_LOCAL_CLIENT_EVENT(name) \
> + DEFINE_EVENT(nfs_local_client_event, name, \
> + TP_PROTO( \
> + const struct nfs_client *clp \
> + ), \
> + TP_ARGS(clp))
> +
> +DEFINE_NFS_LOCAL_CLIENT_EVENT(nfs_local_enable);
> +DEFINE_NFS_LOCAL_CLIENT_EVENT(nfs_local_disable);
> +
> DECLARE_EVENT_CLASS(nfs_xdr_event,
> TP_PROTO(
> const struct xdr_stream *xdr,
> diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> index 57d62db3be5b..b08420b8e664 100644
> --- a/fs/nfs/pagelist.c
> +++ b/fs/nfs/pagelist.c
> @@ -879,6 +879,9 @@ int nfs_initiate_pgio(struct nfs_pageio_descriptor *desc,
> hdr->args.count,
> (unsigned long long)hdr->args.offset);
>
> + if (localio)
> + return nfs_local_doio(clp, localio, hdr, call_ops);
> +
> task = rpc_run_task(&task_setup_data);
> if (IS_ERR(task))
> return PTR_ERR(task);
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index 267bed2a4ceb..b29b0fd5431f 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -1700,6 +1700,9 @@ int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
>
> dprintk("NFS: initiated commit call\n");
>
> + if (localio)
> + return nfs_local_commit(localio, data, call_ops, how);
> +
> task = rpc_run_task(&task_setup_data);
> if (IS_ERR(task))
> return PTR_ERR(task);
> diff --git a/fs/nfsd/Makefile b/fs/nfsd/Makefile
> index b8736a82e57c..78b421778a79 100644
> --- a/fs/nfsd/Makefile
> +++ b/fs/nfsd/Makefile
> @@ -23,3 +23,4 @@ nfsd-$(CONFIG_NFSD_PNFS) += nfs4layouts.o
> nfsd-$(CONFIG_NFSD_BLOCKLAYOUT) += blocklayout.o blocklayoutxdr.o
> nfsd-$(CONFIG_NFSD_SCSILAYOUT) += blocklayout.o blocklayoutxdr.o
> nfsd-$(CONFIG_NFSD_FLEXFILELAYOUT) += flexfilelayout.o flexfilelayoutxdr.o
> +nfsd-$(CONFIG_NFSD_LOCALIO) += localio.o
> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index ad9083ca144b..99631fa56662 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -52,7 +52,7 @@
> #define NFSD_FILE_CACHE_UP (0)
>
> /* We only care about NFSD_MAY_READ/WRITE for this cache */
> -#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE)
> +#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE|NFSD_MAY_LOCALIO)
>
> static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
> static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions);
> diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c
> new file mode 100644
> index 000000000000..e9aa0997f898
> --- /dev/null
> +++ b/fs/nfsd/localio.c
> @@ -0,0 +1,244 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * NFS server support for local clients to bypass network stack
> + *
> + * Copyright (C) 2014 Weston Andros Adamson <dros@primarydata.com>
> + * Copyright (C) 2019 Trond Myklebust <trond.myklebust@hammerspace.com>
> + * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
> + */
> +
> +#include <linux/exportfs.h>
> +#include <linux/sunrpc/svcauth_gss.h>
> +#include <linux/sunrpc/clnt.h>
> +#include <linux/nfs.h>
> +#include <linux/string.h>
> +
> +#include "nfsd.h"
> +#include "vfs.h"
> +#include "netns.h"
> +#include "filecache.h"
> +
> +#define NFSDDBG_FACILITY NFSDDBG_FH
> +
> +/*
> + * We need to translate between nfs status return values and
> + * the local errno values which may not be the same.
> + * - duplicated from fs/nfs/nfs2xdr.c to avoid needless bloat of
> + * all compiled nfs objects if it were in include/linux/nfs.h
> + */
> +static const struct {
> + int stat;
> + int errno;
> +} nfs_common_errtbl[] = {
> + { NFS_OK, 0 },
> + { NFSERR_PERM, -EPERM },
> + { NFSERR_NOENT, -ENOENT },
> + { NFSERR_IO, -EIO },
> + { NFSERR_NXIO, -ENXIO },
> +/* { NFSERR_EAGAIN, -EAGAIN }, */
> + { NFSERR_ACCES, -EACCES },
> + { NFSERR_EXIST, -EEXIST },
> + { NFSERR_XDEV, -EXDEV },
> + { NFSERR_NODEV, -ENODEV },
> + { NFSERR_NOTDIR, -ENOTDIR },
> + { NFSERR_ISDIR, -EISDIR },
> + { NFSERR_INVAL, -EINVAL },
> + { NFSERR_FBIG, -EFBIG },
> + { NFSERR_NOSPC, -ENOSPC },
> + { NFSERR_ROFS, -EROFS },
> + { NFSERR_MLINK, -EMLINK },
> + { NFSERR_NAMETOOLONG, -ENAMETOOLONG },
> + { NFSERR_NOTEMPTY, -ENOTEMPTY },
> + { NFSERR_DQUOT, -EDQUOT },
> + { NFSERR_STALE, -ESTALE },
> + { NFSERR_REMOTE, -EREMOTE },
> +#ifdef EWFLUSH
> + { NFSERR_WFLUSH, -EWFLUSH },
> +#endif
> + { NFSERR_BADHANDLE, -EBADHANDLE },
> + { NFSERR_NOT_SYNC, -ENOTSYNC },
> + { NFSERR_BAD_COOKIE, -EBADCOOKIE },
> + { NFSERR_NOTSUPP, -ENOTSUPP },
> + { NFSERR_TOOSMALL, -ETOOSMALL },
> + { NFSERR_SERVERFAULT, -EREMOTEIO },
> + { NFSERR_BADTYPE, -EBADTYPE },
> + { NFSERR_JUKEBOX, -EJUKEBOX },
> + { -1, -EIO }
> +};
> +
> +/**
> + * nfs_stat_to_errno - convert an NFS status code to a local errno
> + * @status: NFS status code to convert
> + *
> + * Returns a local errno value, or -EIO if the NFS status code is
> + * not recognized. This function is used jointly by NFSv2 and NFSv3.
> + */
> +static int nfs_stat_to_errno(enum nfs_stat status)
> +{
> + int i;
> +
> + for (i = 0; nfs_common_errtbl[i].stat != -1; i++) {
> + if (nfs_common_errtbl[i].stat == (int)status)
> + return nfs_common_errtbl[i].errno;
> + }
> + return nfs_common_errtbl[i].errno;
> +}
> +
> +static void
> +nfsd_local_fakerqst_destroy(struct svc_rqst *rqstp)
> +{
> + if (rqstp->rq_client)
> + auth_domain_put(rqstp->rq_client);
> + if (rqstp->rq_cred.cr_group_info)
> + put_group_info(rqstp->rq_cred.cr_group_info);
> + /* rpcauth_map_to_svc_cred_local() clears cr_principal */
> + WARN_ON_ONCE(rqstp->rq_cred.cr_principal != NULL);
> + kfree(rqstp->rq_xprt);
> + kfree(rqstp);
> +}
> +
> +static struct svc_rqst *
> +nfsd_local_fakerqst_create(struct net *net, struct rpc_clnt *rpc_clnt,
> + const struct cred *cred)
> +{
> + struct svc_rqst *rqstp;
> + struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> + int status;
> +
> + /* FIXME: not running in nfsd context, must get reference on nfsd_serv */
> + if (unlikely(!READ_ONCE(nn->nfsd_serv))) {
> + dprintk("%s: localio denied. Server not running\n", __func__);
> + return ERR_PTR(-ENXIO);
> + }
> +
> + rqstp = kzalloc(sizeof(*rqstp), GFP_KERNEL);
> + if (!rqstp)
> + return ERR_PTR(-ENOMEM);
> +
> + rqstp->rq_xprt = kzalloc(sizeof(*rqstp->rq_xprt), GFP_KERNEL);
> + if (!rqstp->rq_xprt) {
> + status = -ENOMEM;
> + goto out_err;
> + }
> +
> + rqstp->rq_xprt->xpt_net = net;
> + __set_bit(RQ_SECURE, &rqstp->rq_flags);
> + rqstp->rq_proc = 1;
> + rqstp->rq_vers = 3;
> + rqstp->rq_prot = IPPROTO_TCP;
> + rqstp->rq_server = nn->nfsd_serv;
> +
> + /* Note: we're connecting to ourself, so source addr == peer addr */
> + rqstp->rq_addrlen = rpc_peeraddr(rpc_clnt,
> + (struct sockaddr *)&rqstp->rq_addr,
> + sizeof(rqstp->rq_addr));
> +
> + rpcauth_map_to_svc_cred_local(rpc_clnt->cl_auth, cred, &rqstp->rq_cred);
> +
> + /*
> + * set up enough for svcauth_unix_set_client to be able to wait
> + * for the cache downcall. Note that we do _not_ want to allow the
> + * request to be deferred for later revisit since this rqst and xprt
> + * are not set up to run inside of the normal svc_rqst engine.
> + */
> + INIT_LIST_HEAD(&rqstp->rq_xprt->xpt_deferred);
> + kref_init(&rqstp->rq_xprt->xpt_ref);
> + spin_lock_init(&rqstp->rq_xprt->xpt_lock);
> + rqstp->rq_chandle.thread_wait = 5 * HZ;
> +
> + status = svcauth_unix_set_client(rqstp);
> + switch (status) {
> + case SVC_OK:
> + break;
> + case SVC_DENIED:
> + status = -ENXIO;
> + dprintk("%s: client %pISpc denied localio access\n",
> + __func__, (struct sockaddr *)&rqstp->rq_addr);
> + goto out_err;
> + default:
> + status = -ETIMEDOUT;
> + dprintk("%s: client %pISpc temporarily denied localio access\n",
> + __func__, (struct sockaddr *)&rqstp->rq_addr);
> + goto out_err;
> + }
> +
> + return rqstp;
> +
> +out_err:
> + nfsd_local_fakerqst_destroy(rqstp);
> + return ERR_PTR(status);
> +}
> +
> +/*
> + * nfsd_open_local_fh - lookup a local filehandle @nfs_fh and map to @file
> + *
> + * This function maps a local fh to a path on a local filesystem.
> + * This is useful when the nfs client has the local server mounted - it can
> + * avoid all the NFS overhead with reads, writes and commits.
> + *
> + * on successful return, caller is responsible for calling path_put. Also
> + * note that this is called from nfs.ko via find_symbol() to avoid an explicit
> + * dependency on knfsd. So, there is no forward declaration in a header file
> + * for it.
> + */
> +int nfsd_open_local_fh(struct net *net,
> + struct rpc_clnt *rpc_clnt,
> + const struct cred *cred,
> + const struct nfs_fh *nfs_fh,
> + const fmode_t fmode,
> + struct file **pfilp)
> +{
> + const struct cred *save_cred;
> + struct svc_rqst *rqstp;
> + struct svc_fh fh;
> + struct nfsd_file *nf;
> + int status = 0;
> + int mayflags = NFSD_MAY_LOCALIO;
> + __be32 beres;
> +
> + /* Save creds before calling into nfsd */
> + save_cred = get_current_cred();
> +
> + rqstp = nfsd_local_fakerqst_create(net, rpc_clnt, cred);
> + if (IS_ERR(rqstp)) {
> + status = PTR_ERR(rqstp);
> + goto out_revertcred;
> + }
> +
> + /* nfs_fh -> svc_fh */
> + if (nfs_fh->size > NFS4_FHSIZE) {
> + status = -EINVAL;
> + goto out;
> + }
> + fh_init(&fh, NFS4_FHSIZE);
> + fh.fh_handle.fh_size = nfs_fh->size;
> + memcpy(fh.fh_handle.fh_raw, nfs_fh->data, nfs_fh->size);
> +
> + if (fmode & FMODE_READ)
> + mayflags |= NFSD_MAY_READ;
> + if (fmode & FMODE_WRITE)
> + mayflags |= NFSD_MAY_WRITE;
> +
> + beres = nfsd_file_acquire(rqstp, &fh, mayflags, &nf);
> + if (beres) {
> + status = nfs_stat_to_errno(be32_to_cpu(beres));
> + dprintk("%s: fh_verify failed %d\n", __func__, status);
> + goto out_fh_put;
> + }
> +
> + *pfilp = get_file(nf->nf_file);
> +
> + nfsd_file_put(nf);
> +out_fh_put:
> + fh_put(&fh);
> +
> +out:
> + nfsd_local_fakerqst_destroy(rqstp);
> +out_revertcred:
> + revert_creds(save_cred);
> + return status;
> +}
> +EXPORT_SYMBOL_GPL(nfsd_open_local_fh);
> +
> +/* Compile time type checking, not used by anything */
> +static nfs_to_nfsd_open_t __maybe_unused nfsd_open_local_fh_typecheck = nfsd_open_local_fh;
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index 1222a0a33fe1..a477d2c5088a 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -431,6 +431,7 @@ static int nfsd_startup_net(struct net *net, const struct cred *cred)
> #endif
> #if IS_ENABLED(CONFIG_NFSD_LOCALIO)
> INIT_LIST_HEAD(&nn->nfsd_uuid.list);
> + nn->nfsd_uuid.net = net;
> list_add_tail_rcu(&nn->nfsd_uuid.list, &nfsd_uuids);
> #endif
> nn->nfsd_net_up = true;
> diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
> index 77bbd23aa150..9c0610fdd11c 100644
> --- a/fs/nfsd/trace.h
> +++ b/fs/nfsd/trace.h
> @@ -86,7 +86,8 @@ DEFINE_NFSD_XDR_ERR_EVENT(cant_encode);
> { NFSD_MAY_NOT_BREAK_LEASE, "NOT_BREAK_LEASE" }, \
> { NFSD_MAY_BYPASS_GSS, "BYPASS_GSS" }, \
> { NFSD_MAY_READ_IF_EXEC, "READ_IF_EXEC" }, \
> - { NFSD_MAY_64BIT_COOKIE, "64BIT_COOKIE" })
> + { NFSD_MAY_64BIT_COOKIE, "64BIT_COOKIE" }, \
> + { NFSD_MAY_LOCALIO, "LOCALIO" })
>
> TRACE_EVENT(nfsd_compound,
> TP_PROTO(
> diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
> index 57cd70062048..af07bb146e81 100644
> --- a/fs/nfsd/vfs.h
> +++ b/fs/nfsd/vfs.h
> @@ -36,6 +36,8 @@
> #define NFSD_MAY_CREATE (NFSD_MAY_EXEC|NFSD_MAY_WRITE)
> #define NFSD_MAY_REMOVE (NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC)
>
> +#define NFSD_MAY_LOCALIO 0x800000
> +
> struct nfsd_file;
>
> /*
> @@ -158,6 +160,13 @@ __be32 nfsd_permission(struct svc_rqst *, struct svc_export *,
>
> void nfsd_filp_close(struct file *fp);
>
> +int nfsd_open_local_fh(struct net *net,
> + struct rpc_clnt *rpc_clnt,
> + const struct cred *cred,
> + const struct nfs_fh *nfs_fh,
> + const fmode_t fmode,
> + struct file **pfilp);
> +
> static inline int fh_want_write(struct svc_fh *fh)
> {
> int ret;
> diff --git a/include/linux/nfs.h b/include/linux/nfs.h
> index ceb70a926b95..64ed672a0b34 100644
> --- a/include/linux/nfs.h
> +++ b/include/linux/nfs.h
> @@ -8,6 +8,8 @@
> #ifndef _LINUX_NFS_H
> #define _LINUX_NFS_H
>
> +#include <linux/cred.h>
> +#include <linux/sunrpc/auth.h>
> #include <linux/sunrpc/msg_prot.h>
> #include <linux/string.h>
> #include <linux/crc32.h>
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 039898d70954..a0bb947fdd1d 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -96,6 +96,8 @@ struct nfs_open_context {
> struct list_head list;
> struct nfs4_threshold *mdsthreshold;
> struct rcu_head rcu_head;
> +
> + struct file *local_filp;
> };
>
> struct nfs_open_dir_context {
> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
> index e58e706a6503..4290c550a049 100644
> --- a/include/linux/nfs_fs_sb.h
> +++ b/include/linux/nfs_fs_sb.h
> @@ -50,6 +50,7 @@ struct nfs_client {
> #define NFS_CS_DS 7 /* - Server is a DS */
> #define NFS_CS_REUSEPORT 8 /* - reuse src port on reconnect */
> #define NFS_CS_PNFS 9 /* - Server used for pnfs */
> +#define NFS_CS_LOCAL_IO 10 /* - client is local */
> struct sockaddr_storage cl_addr; /* server identifier */
> size_t cl_addrlen;
> char * cl_hostname; /* hostname of server */
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index d09b9773b20c..764513a61601 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -1605,6 +1605,7 @@ enum {
> NFS_IOHDR_RESEND_PNFS,
> NFS_IOHDR_RESEND_MDS,
> NFS_IOHDR_UNSTABLE_WRITES,
> + NFS_IOHDR_ODIRECT,
> };
>
> struct nfs_io_completion;
> --
> 2.44.0
>
>
>

Thanks,
NeilBrown