On Sun, 2022-09-04 at 15:51 -0400, David Wysochanski wrote:
> On Sun, Sep 4, 2022 at 9:59 AM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> >
> > On Sun, 2022-09-04 at 05:05 -0400, Dave Wysochanski wrote:
> > > Convert the NFS buffered read code paths to corresponding netfs APIs,
> > > but only when fscache is configured and enabled.
> > >
> > > The netfs API defines struct netfs_request_ops which must be filled
> > > in by the network filesystem. For NFS, we only need to define 5 of
> > > the functions, the main one being the issue_read() function.
> > > The issue_read() function is called by the netfs layer when a read
> > > cannot be fulfilled locally, and must be sent to the server (either
> > > the cache is not active, or it is active but the data is not available).
> > > Once the read from the server is complete, netfs requires a call to
> > > netfs_subreq_terminated() which conveys either how many bytes were read
> > > successfully, or an error. Note that issue_read() is called with a
> > > structure, netfs_io_subrequest, which defines the IO requested, and
> > > contains a start and a length (both in bytes), and assumes the underlying
> > > netfs will return a either an error on the whole region, or the number
> > > of bytes successfully read.
> > >
> > > The NFS IO path is page based and the main APIs are the pgio APIs defined
> > > in pagelist.c. For the pgio APIs, there is no way for the caller to
> > > know how many RPCs will be sent and how the pages will be broken up
> > > into underlying RPCs, each of which will have their own return code.
> > > Thus, NFS needs some way to accommodate the netfs API requirement on
> > > the single response to the whole request, while also minimizing
> > > disruptive changes to the NFS pgio layer. The approach taken with this
> > > patch is to allocate a small structure for each nfs_netfs_issue_read() call
> > > to keep the final error value or the number of bytes successfully read.
> > > The refcount on the structure is used also as a marker for the last
> > > RPC completion, updated inside nfs_netfs_read_initiate(), and
> > > nfs_netfs_read_done(), when a nfs_pgio_header contains a valid pointer
> > > to the data. Then finally in nfs_read_completion(), call into
> > > nfs_netfs_read_completion() to update the final error value and bytes
> > > read, and check the refcount to determine whether this is the final
> > > RPC completion. If this is the last RPC, then in the final put on
> > > the structure, call into netfs_subreq_terminated() with the final
> > > error value or the number of bytes successfully transferred.
> > >
> > > Suggested-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > > Signed-off-by: Dave Wysochanski <dwysocha@xxxxxxxxxx>
> > > ---
> > > fs/nfs/fscache.c | 241 ++++++++++++++++++++++++---------------
> > > fs/nfs/fscache.h | 94 +++++++++------
> > > fs/nfs/inode.c | 2 +
> > > fs/nfs/internal.h | 9 ++
> > > fs/nfs/pagelist.c | 12 ++
> > > fs/nfs/read.c | 51 ++++-----
> > > include/linux/nfs_page.h | 3 +
> > > include/linux/nfs_xdr.h | 3 +
> > > 8 files changed, 263 insertions(+), 152 deletions(-)
> > >
> > > diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
> > > index a6fc1c8b6644..9b7df3d61c35 100644
> > > --- a/fs/nfs/fscache.c
> > > +++ b/fs/nfs/fscache.c
> > > @@ -15,6 +15,9 @@
> > > #include <linux/seq_file.h>
> > > #include <linux/slab.h>
> > > #include <linux/iversion.h>
> > > +#include <linux/xarray.h>
> > > +#include <linux/fscache.h>
> > > +#include <linux/netfs.h>
> > >
> > > #include "internal.h"
> > > #include "iostat.h"
> > > @@ -184,7 +187,7 @@ void nfs_fscache_init_inode(struct inode *inode)
> > > */
> > > void nfs_fscache_clear_inode(struct inode *inode)
> > > {
> > > - fscache_relinquish_cookie(netfs_i_cookie(&NFS_I(inode)->netfs), false);
> > > + fscache_relinquish_cookie(netfs_i_cookie(netfs_inode(inode)), false);
> > > netfs_inode(inode)->cache = NULL;
> > > }
> > >
> > > @@ -210,7 +213,7 @@ void nfs_fscache_clear_inode(struct inode *inode)
> > > void nfs_fscache_open_file(struct inode *inode, struct file *filp)
> > > {
> > > struct nfs_fscache_inode_auxdata auxdata;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > + struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
> > > bool open_for_write = inode_is_open_for_write(inode);
> > >
> > > if (!fscache_cookie_valid(cookie))
> > > @@ -228,119 +231,169 @@ EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
> > > void nfs_fscache_release_file(struct inode *inode, struct file *filp)
> > > {
> > > struct nfs_fscache_inode_auxdata auxdata;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > + struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
> > > loff_t i_size = i_size_read(inode);
> > >
> > > nfs_fscache_update_auxdata(&auxdata, inode);
> > > fscache_unuse_cookie(cookie, &auxdata, &i_size);
> > > }
> > >
> > > -/*
> > > - * Fallback page reading interface.
> > > - */
> > > -static int fscache_fallback_read_page(struct inode *inode, struct page *page)
> > > +int nfs_netfs_read_folio(struct file *file, struct folio *folio)
> > > {
> > > - struct netfs_cache_resources cres;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > - struct iov_iter iter;
> > > - struct bio_vec bvec[1];
> > > - int ret;
> > > -
> > > - memset(&cres, 0, sizeof(cres));
> > > - bvec[0].bv_page = page;
> > > - bvec[0].bv_offset = 0;
> > > - bvec[0].bv_len = PAGE_SIZE;
> > > - iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > -
> > > - ret = fscache_begin_read_operation(&cres, cookie);
> > > - if (ret < 0)
> > > - return ret;
> > > -
> > > - ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
> > > - NULL, NULL);
> > > - fscache_end_operation(&cres);
> > > - return ret;
> > > + if (!netfs_inode(folio_inode(folio))->cache)
> > > + return -ENOBUFS;
> > > +
> > > + return netfs_read_folio(file, folio);
> > > }
> > >
> > > -/*
> > > - * Fallback page writing interface.
> > > - */
> > > -static int fscache_fallback_write_page(struct inode *inode, struct page *page,
> > > - bool no_space_allocated_yet)
> > > +int nfs_netfs_readahead(struct readahead_control *ractl)
> > > {
> > > - struct netfs_cache_resources cres;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > - struct iov_iter iter;
> > > - struct bio_vec bvec[1];
> > > - loff_t start = page_offset(page);
> > > - size_t len = PAGE_SIZE;
> > > - int ret;
> > > -
> > > - memset(&cres, 0, sizeof(cres));
> > > - bvec[0].bv_page = page;
> > > - bvec[0].bv_offset = 0;
> > > - bvec[0].bv_len = PAGE_SIZE;
> > > - iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > -
> > > - ret = fscache_begin_write_operation(&cres, cookie);
> > > - if (ret < 0)
> > > - return ret;
> > > -
> > > - ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
> > > - no_space_allocated_yet);
> > > - if (ret == 0)
> > > - ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
> > > - fscache_end_operation(&cres);
> > > - return ret;
> > > + struct inode *inode = ractl->mapping->host;
> > > +
> > > + if (!netfs_inode(inode)->cache)
> > > + return -ENOBUFS;
> > > +
> > > + netfs_readahead(ractl);
> > > + return 0;
> > > }
> > >
> > > -/*
> > > - * Retrieve a page from fscache
> > > - */
> > > -int __nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > +atomic_t nfs_netfs_debug_id;
> > > +static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
> > > {
> > > - int ret;
> > > + rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
> > > + rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
> > >
> > > - trace_nfs_fscache_read_page(inode, page);
> > > - if (PageChecked(page)) {
> > > - ClearPageChecked(page);
> > > - ret = 1;
> > > - goto out;
> > > - }
> > > + return 0;
> > > +}
> > >
> > > - ret = fscache_fallback_read_page(inode, page);
> > > - if (ret < 0) {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
> > > - SetPageChecked(page);
> > > - goto out;
> > > - }
> > > +static void nfs_netfs_free_request(struct netfs_io_request *rreq)
> > > +{
> > > + put_nfs_open_context(rreq->netfs_priv);
> > > +}
> > >
> > > - /* Read completed synchronously */
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
> > > - SetPageUptodate(page);
> > > - ret = 0;
> > > -out:
> > > - trace_nfs_fscache_read_page_exit(inode, page, ret);
> > > - return ret;
> > > +static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
> > > +{
> > > + return fscache_begin_read_operation(&rreq->cache_resources,
> > > + netfs_i_cookie(netfs_inode(rreq->inode)));
> > > }
> > >
> > > -/*
> > > - * Store a newly fetched page in fscache. We can be certain there's no page
> > > - * stored in the cache as yet otherwise we would've read it from there.
> > > - */
> > > -void __nfs_fscache_write_page(struct inode *inode, struct page *page)
> > > +static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
> > > {
> > > - int ret;
> > > + struct nfs_netfs_io_data *netfs;
> > > +
> > > + netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
> > > + if (!netfs)
> > > + return NULL;
> > > + netfs->sreq = sreq;
> > > + refcount_set(&netfs->refcount, 1);
> > > + return netfs;
> > > +}
> > >
> > > - trace_nfs_fscache_write_page(inode, page);
> > > +static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
> > > +{
> > > + size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
> > >
> > > - ret = fscache_fallback_write_page(inode, page, true);
> > > + sreq->len = min(sreq->len, rsize);
> > > + return true;
> > > +}
> > >
> > > - if (ret != 0) {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > - } else {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
> > > +static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
> > > +{
> > > + struct nfs_pageio_descriptor pgio;
> > > + struct inode *inode = sreq->rreq->inode;
> > > + struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
> > > + struct page *page;
> > > + int err;
> > > + pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
> > > + pgoff_t last = ((sreq->start + sreq->len -
> > > + sreq->transferred - 1) >> PAGE_SHIFT);
> > > + XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
> > > +
> > > + nfs_pageio_init_read(&pgio, inode, false,
> > > + &nfs_async_read_completion_ops);
> > > +
> > > + pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
> > > + if (!pgio.pg_netfs)
> > > + return netfs_subreq_terminated(sreq, -ENOMEM, false);
> > > +
> > > + xas_lock(&xas);
> > > + xas_for_each(&xas, page, last) {
> > > + /* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs */
> > > + xas_pause(&xas);
> > > + xas_unlock(&xas);
> > > + err = nfs_pageio_add_page(&pgio, ctx, page);
> > > + if (err < 0)
> > > + return netfs_subreq_terminated(sreq, err, false);
> > > + xas_lock(&xas);
> > > }
> > > - trace_nfs_fscache_write_page_exit(inode, page, ret);
> > > + xas_unlock(&xas);
> > > + nfs_pageio_complete_read(&pgio);
> > > + nfs_netfs_put(pgio.pg_netfs);
> > > }
> > > +
> > > +void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr)
> > > +{
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > +
> > > + if (!netfs)
> > > + return;
> > > +
> > > + nfs_netfs_get(netfs);
> > > +}
> > > +
> > > +void nfs_netfs_readpage_done(struct nfs_pgio_header *hdr)
> > > +{
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > +
> > > + if (!netfs)
> > > + return;
> > > +
> > > + if (hdr->res.op_status)
> > > + /*
> > > + * Retryable errors such as BAD_STATEID will be re-issued,
> > > + * so reduce refcount.
> > > + */
> > > + nfs_netfs_put(netfs);
> > > +}
> > > +
> > > +void nfs_netfs_readpage_release(struct nfs_page *req)
> > > +{
> > > + struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > +
> > > + /*
> > > + * If fscache is enabled, netfs will unlock pages.
> > > + */
> > > + if (netfs_inode(inode)->cache)
> > > + return;
> > > +
> > > + unlock_page(req->wb_page);
> > > +}
> > > +
> > > +void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
> > > +{
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > + struct netfs_io_subrequest *sreq;
> > > +
> > > + if (!netfs)
> > > + return;
> > > +
> > > + sreq = netfs->sreq;
> > > + if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
> > > + __set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
> > > +
> > > + if (hdr->error)
> > > + netfs->error = hdr->error;
> > > + else
> > > + atomic64_add(hdr->res.count, &netfs->transferred);
> > > +
> > > + nfs_netfs_put(netfs);
> > > + hdr->netfs = NULL;
> > > +}
> > > +
> > > +const struct netfs_request_ops nfs_netfs_ops = {
> > > + .init_request = nfs_netfs_init_request,
> > > + .free_request = nfs_netfs_free_request,
> > > + .begin_cache_operation = nfs_netfs_begin_cache_operation,
> > > + .issue_read = nfs_netfs_issue_read,
> > > + .clamp_length = nfs_netfs_clamp_length
> > > +};
> > > diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
> > > index 38614ed8f951..fb782b917235 100644
> > > --- a/fs/nfs/fscache.h
> > > +++ b/fs/nfs/fscache.h
> > > @@ -34,6 +34,49 @@ struct nfs_fscache_inode_auxdata {
> > > u64 change_attr;
> > > };
> > >
> > > +struct nfs_netfs_io_data {
> > > + /*
> > > + * NFS may split a netfs_io_subrequest into multiple RPCs, each
> > > + * with their own read completion. In netfs, we can only call
> > > + * netfs_subreq_terminated() once for each subrequest. Use the
> > > + * refcount here to double as a marker of the last RPC completion,
> > > + * and only call netfs via netfs_subreq_terminated() once.
> > > + */
> > > + refcount_t refcount;
> > > + struct netfs_io_subrequest *sreq;
> > > +
> > > + /*
> > > + * Final disposition of the netfs_io_subrequest, sent in
> > > + * netfs_subreq_terminated()
> > > + */
> > > + atomic64_t transferred;
> > > + int error;
> > > +};
> > > +
> > > +static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
> > > +{
> > > + refcount_inc(&netfs->refcount);
> > > +}
> > > +
> > > +static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
> > > +{
> > > + /* Only the last RPC completion should call netfs_subreq_terminated() */
> > > + if (refcount_dec_and_test(&netfs->refcount)) {
> > > + netfs_subreq_terminated(netfs->sreq,
> > > + netfs->error ?: atomic64_read(&netfs->transferred),
> > > + false);
> > > + kfree(netfs);
> > > + }
> > > +}
> > > +static inline void nfs_netfs_inode_init(struct nfs_inode *nfsi)
> > > +{
> > > + netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
> > > +}
> > > +extern void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr);
> > > +extern void nfs_netfs_readpage_done(struct nfs_pgio_header *hdr);
> > > +extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
> > > +extern void nfs_netfs_readpage_release(struct nfs_page *req);
> > > +
> > > /*
> > > * fscache.c
> > > */
> > > @@ -44,9 +87,8 @@ extern void nfs_fscache_init_inode(struct inode *);
> > > extern void nfs_fscache_clear_inode(struct inode *);
> > > extern void nfs_fscache_open_file(struct inode *, struct file *);
> > > extern void nfs_fscache_release_file(struct inode *, struct file *);
> > > -
> > > -extern int __nfs_fscache_read_page(struct inode *, struct page *);
> > > -extern void __nfs_fscache_write_page(struct inode *, struct page *);
> > > +extern int nfs_netfs_readahead(struct readahead_control *ractl);
> > > +extern int nfs_netfs_read_folio(struct file *file, struct folio *folio);
> > >
> > > static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > {
> > > @@ -54,34 +96,11 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > if (current_is_kswapd() || !(gfp & __GFP_FS))
> > > return false;
> > > folio_wait_fscache(folio);
> > > - fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > - nfs_inc_fscache_stats(folio->mapping->host,
> > > - NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > }
> > > + fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > return true;
> > > }
> > >
> > > -/*
> > > - * Retrieve a page from an inode data storage object.
> > > - */
> > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > -{
> > > - if (netfs_inode(inode)->cache)
> > > - return __nfs_fscache_read_page(inode, page);
> > > - return -ENOBUFS;
> > > -}
> > > -
> > > -/*
> > > - * Store a page newly fetched from the server in an inode data storage object
> > > - * in the cache.
> > > - */
> > > -static inline void nfs_fscache_write_page(struct inode *inode,
> > > - struct page *page)
> > > -{
> > > - if (netfs_inode(inode)->cache)
> > > - __nfs_fscache_write_page(inode, page);
> > > -}
> > > -
> > > static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
> > > struct inode *inode)
> > > {
> > > @@ -118,6 +137,14 @@ static inline const char *nfs_server_fscache_state(struct nfs_server *server)
> > > }
> > >
> > > #else /* CONFIG_NFS_FSCACHE */
> > > +static inline void nfs_netfs_inode_init(struct nfs_inode *nfsi) {}
> > > +static inline void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr) {}
> > > +static inline void nfs_netfs_readpage_done(struct nfs_pgio_header *hdr) {}
> > > +static inline void nfs_netfs_read_completion(struct nfs_pgio_header *hdr) {}
> > > +static inline void nfs_netfs_readpage_release(struct nfs_page *req)
> > > +{
> > > + unlock_page(req->wb_page);
> > > +}
> > > static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
> > >
> > > static inline void nfs_fscache_init_inode(struct inode *inode) {}
> > > @@ -125,16 +152,19 @@ static inline void nfs_fscache_clear_inode(struct inode *inode) {}
> > > static inline void nfs_fscache_open_file(struct inode *inode,
> > > struct file *filp) {}
> > > static inline void nfs_fscache_release_file(struct inode *inode, struct file *file) {}
> > > -
> > > -static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > +static inline int nfs_netfs_readahead(struct readahead_control *ractl)
> > > {
> > > - return true; /* may release folio */
> > > + return -ENOBUFS;
> > > }
> > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > +static inline int nfs_netfs_read_folio(struct file *file, struct folio *folio)
> > > {
> > > return -ENOBUFS;
> > > }
> > > -static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
> > > +
> > > +static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > +{
> > > + return true; /* may release folio */
> > > +}
> > > static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
> > >
> > > static inline const char *nfs_server_fscache_state(struct nfs_server *server)
> > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> > > index aa2aec785ab5..b36a02b932e8 100644
> > > --- a/fs/nfs/inode.c
> > > +++ b/fs/nfs/inode.c
> > > @@ -2249,6 +2249,8 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
> > > #ifdef CONFIG_NFS_V4_2
> > > nfsi->xattr_cache = NULL;
> > > #endif
> > > + nfs_netfs_inode_init(nfsi);
> > > +
> > > return VFS_I(nfsi);
> > > }
> > > EXPORT_SYMBOL_GPL(nfs_alloc_inode);
> > > diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> > > index 273687082992..e5589036c1f8 100644
> > > --- a/fs/nfs/internal.h
> > > +++ b/fs/nfs/internal.h
> > > @@ -453,6 +453,10 @@ extern void nfs_sb_deactive(struct super_block *sb);
> > > extern int nfs_client_for_each_server(struct nfs_client *clp,
> > > int (*fn)(struct nfs_server *, void *),
> > > void *data);
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > +extern const struct netfs_request_ops nfs_netfs_ops;
> > > +#endif
> > > +
> > > /* io.c */
> > > extern void nfs_start_io_read(struct inode *inode);
> > > extern void nfs_end_io_read(struct inode *inode);
> > > @@ -482,9 +486,14 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
> > >
> > > struct nfs_pgio_completion_ops;
> > > /* read.c */
> > > +extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > struct inode *inode, bool force_mds,
> > > const struct nfs_pgio_completion_ops *compl_ops);
> > > +extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > + struct nfs_open_context *ctx,
> > > + struct page *page);
> > > +extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
> > > extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
> > > extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
> > >
> > > diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> > > index 317cedfa52bf..e28754476d1b 100644
> > > --- a/fs/nfs/pagelist.c
> > > +++ b/fs/nfs/pagelist.c
> > > @@ -25,6 +25,7 @@
> > > #include "internal.h"
> > > #include "pnfs.h"
> > > #include "nfstrace.h"
> > > +#include "fscache.h"
> > >
> > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > >
> > > @@ -68,6 +69,10 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
> > > hdr->good_bytes = mirror->pg_count;
> > > hdr->io_completion = desc->pg_io_completion;
> > > hdr->dreq = desc->pg_dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + if (desc->pg_netfs)
> > > + hdr->netfs = desc->pg_netfs;
> > > +#endif
> > > hdr->release = release;
> > > hdr->completion_ops = desc->pg_completion_ops;
> > > if (hdr->completion_ops->init_hdr)
> > > @@ -846,6 +851,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
> > > desc->pg_lseg = NULL;
> > > desc->pg_io_completion = NULL;
> > > desc->pg_dreq = NULL;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + desc->pg_netfs = NULL;
> > > +#endif
> > > desc->pg_bsize = bsize;
> > >
> > > desc->pg_mirror_count = 1;
> > > @@ -940,6 +948,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
> > > /* Set up the argument struct */
> > > nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
> > > desc->pg_rpc_callops = &nfs_pgio_common_ops;
> > > +
> > > return 0;
> > > }
> > > EXPORT_SYMBOL_GPL(nfs_generic_pgio);
> > > @@ -1360,6 +1369,9 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
> > >
> > > desc->pg_io_completion = hdr->io_completion;
> > > desc->pg_dreq = hdr->dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + desc->pg_netfs = hdr->netfs;
> > > +#endif
> > > list_splice_init(&hdr->pages, &pages);
> > > while (!list_empty(&pages)) {
> > > struct nfs_page *req = nfs_list_entry(pages.next);
> > > diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> > > index 525e82ea9a9e..c74c5fcba87d 100644
> > > --- a/fs/nfs/read.c
> > > +++ b/fs/nfs/read.c
> > > @@ -30,7 +30,7 @@
> > >
> > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > >
> > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > static const struct nfs_rw_ops nfs_rw_read_ops;
> > >
> > > static struct kmem_cache *nfs_rdata_cachep;
> > > @@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > }
> > > EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
> > >
> > > -static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > +void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > {
> > > struct nfs_pgio_mirror *pgm;
> > > unsigned long npages;
> > > @@ -110,20 +110,13 @@ EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
> > >
> > > static void nfs_readpage_release(struct nfs_page *req, int error)
> > > {
> > > - struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > struct page *page = req->wb_page;
> > >
> > > - dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
> > > - (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
> > > - (long long)req_offset(req));
> > > -
> > > if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
> > > SetPageError(page);
> > > - if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
> > > - if (PageUptodate(page))
> > > - nfs_fscache_write_page(inode, page);
> > > - unlock_page(page);
> > > - }
> > > + if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE))
> > > + nfs_netfs_readpage_release(req);
> > > +
> > > nfs_release_request(req);
> > > }
> > >
> > > @@ -177,6 +170,8 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
> > > nfs_list_remove_request(req);
> > > nfs_readpage_release(req, error);
> > > }
> > > + nfs_netfs_read_completion(hdr);
> > > +
> > > out:
> > > hdr->release(hdr);
> > > }
> > > @@ -187,6 +182,7 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
> > > struct rpc_task_setup *task_setup_data, int how)
> > > {
> > > rpc_ops->read_setup(hdr, msg);
> > > + nfs_netfs_initiate_read(hdr);
> > > trace_nfs_initiate_read(hdr);
> > > }
> > >
> > > @@ -202,7 +198,7 @@ nfs_async_read_error(struct list_head *head, int error)
> > > }
> > > }
> > >
> > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > .error_cleanup = nfs_async_read_error,
> > > .completion = nfs_read_completion,
> > > };
> > > @@ -219,6 +215,7 @@ static int nfs_readpage_done(struct rpc_task *task,
> > > if (status != 0)
> > > return status;
> > >
> > > + nfs_netfs_readpage_done(hdr);
> > > nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
> > > trace_nfs_readpage_done(task, hdr);
> > >
> > > @@ -294,12 +291,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > >
> > > aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
> > >
> > > - if (!IS_SYNC(page->mapping->host)) {
> > > - error = nfs_fscache_read_page(page->mapping->host, page);
> > > - if (error == 0)
> > > - goto out_unlock;
> > > - }
> > > -
> > > new = nfs_create_request(ctx, page, 0, aligned_len);
> > > if (IS_ERR(new))
> > > goto out_error;
> > > @@ -315,8 +306,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > return 0;
> > > out_error:
> > > error = PTR_ERR(new);
> > > -out_unlock:
> > > - unlock_page(page);
> > > out:
> > > return error;
> > > }
> > > @@ -355,6 +344,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > if (NFS_STALE(inode))
> > > goto out_unlock;
> > >
> > > + ret = nfs_netfs_read_folio(file, folio);
> > > + if (!ret)
> > > + goto out;
> > > +
> > > if (file == NULL) {
> > > ret = -EBADF;
> > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > @@ -368,8 +361,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > &nfs_async_read_completion_ops);
> > >
> > > ret = nfs_pageio_add_page(&pgio, ctx, page);
> > > - if (ret)
> > > - goto out;
> > > + if (ret) {
> > > + put_nfs_open_context(ctx);
> > > + goto out_unlock;
> > > + }
> > >
> > > nfs_pageio_complete_read(&pgio);
> > > ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
> > > @@ -378,12 +373,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > if (!PageUptodate(page) && !ret)
> > > ret = xchg(&ctx->error, 0);
> > > }
> > > -out:
> > > put_nfs_open_context(ctx);
> > > - trace_nfs_aop_readpage_done(inode, page, ret);
> > > - return ret;
> > > + goto out;
> > > +
> > > out_unlock:
> > > unlock_page(page);
> > > +out:
> > > trace_nfs_aop_readpage_done(inode, page, ret);
> > > return ret;
> > > }
> > > @@ -405,6 +400,10 @@ void nfs_readahead(struct readahead_control *ractl)
> > > if (NFS_STALE(inode))
> > > goto out;
> > >
> > > + ret = nfs_netfs_readahead(ractl);
> > > + if (!ret)
> > > + goto out;
> > > +
> > > if (file == NULL) {
> > > ret = -EBADF;
> > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
> > > index ba7e2e4b0926..8eeb16d9bacd 100644
> > > --- a/include/linux/nfs_page.h
> > > +++ b/include/linux/nfs_page.h
> > > @@ -101,6 +101,9 @@ struct nfs_pageio_descriptor {
> > > struct pnfs_layout_segment *pg_lseg;
> > > struct nfs_io_completion *pg_io_completion;
> > > struct nfs_direct_req *pg_dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + void *pg_netfs;
> > > +#endif
> >
> >
> > Would it be possible to union this new field with pg_dreq? I don't think
> > they're ever both used in the same desc. There are some places that
> > check for pg_dreq == NULL that would need to be converted to use a new
> > flag or something, but that would allow us to avoid growing this struct.
> >
>
> Yeah it's a good point, though I'm not sure how easy it is.
> I was also thinking about whether to drop the #ifdefs in the two structures
> since the netfs NULL pointers are benign if unused.
>
> Do you mean something like the below - bit fields to indicate whether
> the pointer is used or not? There is an "io_flags" field inside
> nfs_pageio_descriptor. However, it is used for FLUSH_* flags,
> so a new flag involving union members validity doesn't seem to fit there.
> Not sure if this helps, but another way maybe to look at it is that
> after this change, we could have 3 possibilities for nfs_pageio_descriptors
> - netfs: right now only fscache enabled buffered READs are handled
> - direct IO
> - everything else: (neither direct nor netfs)
>
> It may be possible to unionize, but looks a bit tricky with things like
> pnfs resends (see pnfs.c and callers of nfs_pageio_init_read and
> nfs_pageio_init_write). Might need to update the init functions for
> nfs_pageio_descriptor and nfs_pgio_header and looks a bit messy.
> Might be worth it but not sure - may take some time to work it out
> safely.
>
I didn't put a lot of thought into the suggestion. I just noticed that
the two fields aren't used at the same time and count potentially be
unioned.
My thinking was to use the pg_ioflags, but you're right that they are
all named with FLUSH_* prefixes. They could be renamed though. The
bitfield flags are another option tool.
I'm not sure I follow the difficulty with nfs_pageio_init_{read,write}.
In any case, I'll leave it up to Trond/Anna whether they want this done
before merging.
> --- a/include/linux/nfs_page.h
> +++ b/include/linux/nfs_page.h
> @@ -100,10 +100,10 @@ struct nfs_pageio_descriptor {
> const struct nfs_pgio_completion_ops *pg_completion_ops;
> struct pnfs_layout_segment *pg_lseg;
> struct nfs_io_completion *pg_io_completion;
> - struct nfs_direct_req *pg_dreq;
> -#ifdef CONFIG_NFS_FSCACHE
> - void *pg_netfs;
> -#endif
> + union {
> + struct nfs_direct_req *pg_dreq; /* pg_is_direct */
> + void *pg_netfs; /* pg_is_netfs */
> + };
> unsigned int pg_bsize; /* default bsize for mirrors */
>
> u32 pg_mirror_count;
> @@ -113,6 +113,8 @@ struct nfs_pageio_descriptor {
> u32 pg_mirror_idx; /* current mirror */
> unsigned short pg_maxretrans;
> unsigned char pg_moreio : 1;
> + unsigned char pg_is_direct: 1;
> + unsigned char pg_is_netfs: 1;
> };
>
>
>
>
>
> > > unsigned int pg_bsize; /* default bsize for mirrors */
> > >
> > > u32 pg_mirror_count;
> > > diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> > > index e86cf6642d21..e196ef595908 100644
> > > --- a/include/linux/nfs_xdr.h
> > > +++ b/include/linux/nfs_xdr.h
> > > @@ -1619,6 +1619,9 @@ struct nfs_pgio_header {
> > > const struct nfs_rw_ops *rw_ops;
> > > struct nfs_io_completion *io_completion;
> > > struct nfs_direct_req *dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + void *netfs;
> > > +#endif
> > >
> >
> > Maybe also here too?
> >
> > > int pnfs_error;
> > > int error; /* merge with pnfs_error */
> >
> > --
> > Jeff Layton <jlayton@xxxxxxxxxx>
> >
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
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