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Mon, 9 Nov 2020 20:59:56 +0000 (UTC) Received: from [172.16.176.1] (ovpn-64-2.rdu2.redhat.com [10.10.64.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D8FD71001901; Mon, 9 Nov 2020 20:59:54 +0000 (UTC) From: "Benjamin Coddington" To: trondmy@kernel.org Cc: linux-nfs@vger.kernel.org Subject: Re: [PATCH v4 20/21] NFS: Reduce number of RPC calls when doing uncached readdir Date: Mon, 09 Nov 2020 15:59:53 -0500 Message-ID: <58FA369F-46B0-47E6-B7C8-E0205427B0C0@redhat.com> In-Reply-To: <20201107140325.281678-21-trondmy@kernel.org> References: <20201107140325.281678-1-trondmy@kernel.org> <20201107140325.281678-2-trondmy@kernel.org> <20201107140325.281678-3-trondmy@kernel.org> <20201107140325.281678-4-trondmy@kernel.org> <20201107140325.281678-5-trondmy@kernel.org> <20201107140325.281678-6-trondmy@kernel.org> <20201107140325.281678-7-trondmy@kernel.org> <20201107140325.281678-8-trondmy@kernel.org> <20201107140325.281678-9-trondmy@kernel.org> <20201107140325.281678-10-trondmy@kernel.org> <20201107140325.281678-11-trondmy@kernel.org> <20201107140325.281678-12-trondmy@kernel.org> <20201107140325.281678-13-trondmy@kernel.org> <20201107140325.281678-14-trondmy@kernel.org> <20201107140325.281678-15-trondmy@kernel.org> <20201107140325.281678-16-trondmy@kernel.org> <20201107140325.281678-17-trondmy@kernel.org> <20201107140325.281678-18-trondmy@kernel.org> <20201107140325.281678-19-trondmy@kernel.org> <20201107140325.281678-20-trondmy@kernel.org> <20201107140325.281678-21-trondmy@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; format=flowed X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On 7 Nov 2020, at 9:03, trondmy@kernel.org wrote: > From: Trond Myklebust > > If we're doing uncached readdir, allocate multiple pages in order to > try to avoid duplicate RPC calls for the same getdents() call. > > Signed-off-by: Trond Myklebust Reviewed-by: Benjamin Coddington Ben > --- > fs/nfs/dir.c | 79 > ++++++++++++++++++++++++++++++---------------------- > 1 file changed, 46 insertions(+), 33 deletions(-) > > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c > index b6c3501e8f61..238872d116f7 100644 > --- a/fs/nfs/dir.c > +++ b/fs/nfs/dir.c > @@ -694,12 +694,14 @@ void nfs_prime_dcache(struct dentry *parent, > struct nfs_entry *entry, > static int nfs_readdir_page_filler(struct nfs_readdir_descriptor > *desc, > struct nfs_entry *entry, > struct page **xdr_pages, > - struct page *fillme, unsigned int buflen) > + unsigned int buflen, > + struct page **arrays, > + size_t narrays) > { > struct address_space *mapping = desc->file->f_mapping; > struct xdr_stream stream; > struct xdr_buf buf; > - struct page *scratch, *new, *page = fillme; > + struct page *scratch, *new, *page = *arrays; > int status; > > scratch = alloc_page(GFP_KERNEL); > @@ -725,15 +727,22 @@ static int nfs_readdir_page_filler(struct > nfs_readdir_descriptor *desc, > if (status != -ENOSPC) > continue; > > - if (page->mapping != mapping) > - break; > - new = nfs_readdir_page_get_next(mapping, page->index + 1, > - entry->prev_cookie); > - if (!new) > - break; > - if (page != fillme) > - nfs_readdir_page_unlock_and_put(page); > - page = new; > + if (narrays > 1) { > + narrays--; > + arrays++; > + page = *arrays; > + } else { > + if (page->mapping != mapping) > + break; > + new = nfs_readdir_page_get_next(mapping, > + page->index + 1, > + entry->prev_cookie); > + if (!new) > + break; > + if (page != *arrays) > + nfs_readdir_page_unlock_and_put(page); > + page = new; > + } > status = nfs_readdir_add_to_array(entry, page); > } while (!status && !entry->eof); > > @@ -750,7 +759,7 @@ static int nfs_readdir_page_filler(struct > nfs_readdir_descriptor *desc, > break; > } > > - if (page != fillme) > + if (page != *arrays) > nfs_readdir_page_unlock_and_put(page); > > put_page(scratch); > @@ -790,10 +799,11 @@ static struct page > **nfs_readdir_alloc_pages(size_t npages) > } > > static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor > *desc, > - struct page *page, __be32 *verf_arg, > - __be32 *verf_res) > + __be32 *verf_arg, __be32 *verf_res, > + struct page **arrays, size_t narrays) > { > struct page **pages; > + struct page *page = *arrays; > struct nfs_entry *entry; > size_t array_size; > struct inode *inode = file_inode(desc->file); > @@ -835,7 +845,8 @@ static int nfs_readdir_xdr_to_array(struct > nfs_readdir_descriptor *desc, > break; > } > > - status = nfs_readdir_page_filler(desc, entry, pages, page, pglen); > + status = nfs_readdir_page_filler(desc, entry, pages, pglen, > + arrays, narrays); > } while (!status && nfs_readdir_page_needs_filling(page)); > > nfs_readdir_free_pages(pages, array_size); > @@ -884,8 +895,8 @@ static int find_and_lock_cache_page(struct > nfs_readdir_descriptor *desc) > if (!desc->page) > return -ENOMEM; > if (nfs_readdir_page_needs_filling(desc->page)) { > - res = nfs_readdir_xdr_to_array(desc, desc->page, > - nfsi->cookieverf, verf); > + res = nfs_readdir_xdr_to_array(desc, nfsi->cookieverf, verf, > + &desc->page, 1); > if (res < 0) { > nfs_readdir_page_unlock_and_put_cached(desc); > if (res == -EBADCOOKIE || res == -ENOTSYNC) { > @@ -976,35 +987,37 @@ static void nfs_do_filldir(struct > nfs_readdir_descriptor *desc) > */ > static int uncached_readdir(struct nfs_readdir_descriptor *desc) > { > - struct page *page = NULL; > + struct page **arrays; > + size_t i, sz = 16; > __be32 verf[NFS_DIR_VERIFIER_SIZE]; > int status; > > dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie > %Lu\n", > (unsigned long long)desc->dir_cookie); > > - page = alloc_page(GFP_HIGHUSER); > - if (!page) { > - status = -ENOMEM; > - goto out; > - } > + arrays = nfs_readdir_alloc_pages(sz); > + if (!arrays) > + return -ENOMEM; > + for (i = 0; i < sz; i++) > + nfs_readdir_page_init_array(arrays[i], desc->dir_cookie); > > desc->page_index = 0; > desc->last_cookie = desc->dir_cookie; > - desc->page = page; > desc->duped = 0; > > - nfs_readdir_page_init_array(page, desc->dir_cookie); > - status = nfs_readdir_xdr_to_array(desc, page, desc->verf, verf); > - if (status < 0) > - goto out_release; > + status = nfs_readdir_xdr_to_array(desc, desc->verf, verf, arrays, > sz); > > - nfs_do_filldir(desc); > + for (i = 0; !desc->eof && i < sz; i++) { > + desc->page = arrays[i]; > + nfs_do_filldir(desc); > + } > + desc->page = NULL; > + > + > + for (i = 0; i < sz; i++) > + nfs_readdir_clear_array(arrays[i]); > + nfs_readdir_free_pages(arrays, sz); > > - out_release: > - nfs_readdir_clear_array(desc->page); > - nfs_readdir_page_put(desc); > - out: > dfprintk(DIRCACHE, "NFS: %s: returns %d\n", > __func__, status); > return status; > -- > 2.28.0