[PATCH v2 08/18] NFS: Convert buffered reads to use folios

[trondmy@kernel.org]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

Perform a largely mechanical conversion of references to struct page and
page-specific functions to use the folio equivalents.

Note that the fscache functionality remains untouched. Instead we just
pass in the folio page. This should be OK, as long as we use order 0
folios together with fscache.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/internal.h        | 18 +++++++++
 fs/nfs/nfstrace.h        | 12 +++---
 fs/nfs/pagelist.c        | 30 ++++++++++++++
 fs/nfs/read.c            | 86 ++++++++++++++++++++--------------------
 include/linux/nfs_page.h |  4 ++
 5 files changed, 100 insertions(+), 50 deletions(-)

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 6197b165c8c8..529b87336ffa 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -794,6 +794,24 @@ unsigned int nfs_page_length(struct page *page)
 	return 0;
 }
 
+/*
+ * Determine the number of bytes of data the page contains
+ */
+static inline size_t nfs_folio_length(struct folio *folio)
+{
+	loff_t i_size = i_size_read(folio_file_mapping(folio)->host);
+
+	if (i_size > 0) {
+		pgoff_t index = folio_index(folio) >> folio_order(folio);
+		pgoff_t end_index = (i_size - 1) >> folio_shift(folio);
+		if (index < end_index)
+			return folio_size(folio);
+		if (index == end_index)
+			return offset_in_folio(folio, i_size - 1) + 1;
+	}
+	return 0;
+}
+
 /*
  * Convert a umode to a dirent->d_type
  */
diff --git a/fs/nfs/nfstrace.h b/fs/nfs/nfstrace.h
index 642f6921852f..b686b615586e 100644
--- a/fs/nfs/nfstrace.h
+++ b/fs/nfs/nfstrace.h
@@ -936,10 +936,10 @@ TRACE_EVENT(nfs_sillyrename_unlink,
 TRACE_EVENT(nfs_aop_readpage,
 		TP_PROTO(
 			const struct inode *inode,
-			struct page *page
+			struct folio *folio
 		),
 
-		TP_ARGS(inode, page),
+		TP_ARGS(inode, folio),
 
 		TP_STRUCT__entry(
 			__field(dev_t, dev)
@@ -956,7 +956,7 @@ TRACE_EVENT(nfs_aop_readpage,
 			__entry->fileid = nfsi->fileid;
 			__entry->fhandle = nfs_fhandle_hash(&nfsi->fh);
 			__entry->version = inode_peek_iversion_raw(inode);
-			__entry->offset = page_index(page) << PAGE_SHIFT;
+			__entry->offset = folio_file_pos(folio);
 		),
 
 		TP_printk(
@@ -971,11 +971,11 @@ TRACE_EVENT(nfs_aop_readpage,
 TRACE_EVENT(nfs_aop_readpage_done,
 		TP_PROTO(
 			const struct inode *inode,
-			struct page *page,
+			struct folio *folio,
 			int ret
 		),
 
-		TP_ARGS(inode, page, ret),
+		TP_ARGS(inode, folio, ret),
 
 		TP_STRUCT__entry(
 			__field(dev_t, dev)
@@ -993,7 +993,7 @@ TRACE_EVENT(nfs_aop_readpage_done,
 			__entry->fileid = nfsi->fileid;
 			__entry->fhandle = nfs_fhandle_hash(&nfsi->fh);
 			__entry->version = inode_peek_iversion_raw(inode);
-			__entry->offset = page_index(page) << PAGE_SHIFT;
+			__entry->offset = folio_file_pos(folio);
 			__entry->ret = ret;
 		),
 
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index dd99a5d381b3..7a622263a9fc 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -542,6 +542,36 @@ nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 	return ret;
 }
 
+/**
+ * nfs_page_create_from_folio - Create an NFS read/write request.
+ * @ctx: open context to use
+ * @folio: folio to write
+ * @offset: starting offset within the folio for the write
+ * @count: number of bytes to read/write
+ *
+ * The page must be locked by the caller. This makes sure we never
+ * create two different requests for the same page.
+ * User should ensure it is safe to sleep in this function.
+ */
+struct nfs_page *nfs_page_create_from_folio(struct nfs_open_context *ctx,
+					    struct folio *folio,
+					    unsigned int offset,
+					    unsigned int count)
+{
+	struct nfs_lock_context *l_ctx = nfs_get_lock_context(ctx);
+	struct nfs_page *ret;
+
+	if (IS_ERR(l_ctx))
+		return ERR_CAST(l_ctx);
+	ret = nfs_page_create(l_ctx, offset, folio_index(folio), offset, count);
+	if (!IS_ERR(ret)) {
+		nfs_page_assign_folio(ret, folio);
+		nfs_page_group_init(ret, NULL);
+	}
+	nfs_put_lock_context(l_ctx);
+	return ret;
+}
+
 static struct nfs_page *
 nfs_create_subreq(struct nfs_page *req,
 		  unsigned int pgbase,
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 8ae2c8d1219d..bf4154f9b48c 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -49,12 +49,11 @@ static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
 	kmem_cache_free(nfs_rdata_cachep, rhdr);
 }
 
-static
-int nfs_return_empty_page(struct page *page)
+static int nfs_return_empty_folio(struct folio *folio)
 {
-	zero_user(page, 0, PAGE_SIZE);
-	SetPageUptodate(page);
-	unlock_page(page);
+	folio_zero_segment(folio, 0, folio_size(folio));
+	folio_mark_uptodate(folio);
+	folio_unlock(folio);
 	return 0;
 }
 
@@ -111,18 +110,18 @@ 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;
+	struct folio *folio = nfs_page_to_folio(req);
 
 	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);
+		folio_set_error(folio);
 	if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
-		if (PageUptodate(page))
-			nfs_fscache_write_page(inode, page);
-		unlock_page(page);
+		if (folio_test_uptodate(folio))
+			nfs_fscache_write_page(inode, &folio->page);
+		folio_unlock(folio);
 	}
 	nfs_release_request(req);
 }
@@ -135,7 +134,7 @@ struct nfs_readdesc {
 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 {
 	if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
-		SetPageUptodate(req->wb_page);
+		folio_mark_uptodate(nfs_page_to_folio(req));
 }
 
 static void nfs_read_completion(struct nfs_pgio_header *hdr)
@@ -147,7 +146,7 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
 		goto out;
 	while (!list_empty(&hdr->pages)) {
 		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
-		struct page *page = req->wb_page;
+		struct folio *folio = nfs_page_to_folio(req);
 		unsigned long start = req->wb_pgbase;
 		unsigned long end = req->wb_pgbase + req->wb_bytes;
 
@@ -157,14 +156,14 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
 			if (bytes > hdr->good_bytes) {
 				/* nothing in this request was good, so zero
 				 * the full extent of the request */
-				zero_user_segment(page, start, end);
+				folio_zero_segment(folio, start, end);
 
 			} else if (hdr->good_bytes - bytes < req->wb_bytes) {
 				/* part of this request has good bytes, but
 				 * not all. zero the bad bytes */
 				start += hdr->good_bytes - bytes;
 				WARN_ON(start < req->wb_pgbase);
-				zero_user_segment(page, start, end);
+				folio_zero_segment(folio, start, end);
 			}
 		}
 		error = 0;
@@ -281,33 +280,34 @@ static void nfs_readpage_result(struct rpc_task *task,
 		nfs_readpage_retry(task, hdr);
 }
 
-static int
-readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
+static int readpage_async_filler(struct nfs_readdesc *desc, struct folio *folio)
 {
-	struct inode *inode = page_file_mapping(page)->host;
-	unsigned int rsize = NFS_SERVER(inode)->rsize;
+	struct inode *inode = folio_file_mapping(folio)->host;
+	struct nfs_server *server = NFS_SERVER(inode);
+	size_t fsize = folio_size(folio);
+	unsigned int rsize = server->rsize;
 	struct nfs_page *new;
 	unsigned int len, aligned_len;
 	int error;
 
-	len = nfs_page_length(page);
+	len = nfs_folio_length(folio);
 	if (len == 0)
-		return nfs_return_empty_page(page);
+		return nfs_return_empty_folio(folio);
 
-	aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
+	aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize);
 
-	if (!IS_SYNC(page->mapping->host)) {
-		error = nfs_fscache_read_page(page->mapping->host, page);
+	if (!IS_SYNC(inode)) {
+		error = nfs_fscache_read_page(inode, &folio->page);
 		if (error == 0)
 			goto out_unlock;
 	}
 
-	new = nfs_create_request(desc->ctx, page, 0, aligned_len);
+	new = nfs_page_create_from_folio(desc->ctx, folio, 0, aligned_len);
 	if (IS_ERR(new))
 		goto out_error;
 
-	if (len < PAGE_SIZE)
-		zero_user_segment(page, len, PAGE_SIZE);
+	if (len < fsize)
+		folio_zero_segment(folio, len, fsize);
 	if (!nfs_pageio_add_request(&desc->pgio, new)) {
 		nfs_list_remove_request(new);
 		error = desc->pgio.pg_error;
@@ -318,7 +318,7 @@ readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
 out_error:
 	error = PTR_ERR(new);
 out_unlock:
-	unlock_page(page);
+	folio_unlock(folio);
 out:
 	return error;
 }
@@ -331,25 +331,24 @@ readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
  */
 int nfs_read_folio(struct file *file, struct folio *folio)
 {
-	struct page *page = &folio->page;
 	struct nfs_readdesc desc;
-	struct inode *inode = page_file_mapping(page)->host;
+	struct inode *inode = file_inode(file);
 	int ret;
 
-	trace_nfs_aop_readpage(inode, page);
+	trace_nfs_aop_readpage(inode, folio);
 	nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 
 	/*
 	 * Try to flush any pending writes to the file..
 	 *
-	 * NOTE! Because we own the page lock, there cannot
+	 * NOTE! Because we own the folio lock, there cannot
 	 * be any new pending writes generated at this point
-	 * for this page (other pages can be written to).
+	 * for this folio (other folios can be written to).
 	 */
-	ret = nfs_wb_page(inode, page);
+	ret = nfs_wb_folio(inode, folio);
 	if (ret)
 		goto out_unlock;
-	if (PageUptodate(page))
+	if (folio_test_uptodate(folio))
 		goto out_unlock;
 
 	ret = -ESTALE;
@@ -368,24 +367,24 @@ int nfs_read_folio(struct file *file, struct folio *folio)
 	nfs_pageio_init_read(&desc.pgio, inode, false,
 			     &nfs_async_read_completion_ops);
 
-	ret = readpage_async_filler(&desc, page);
+	ret = readpage_async_filler(&desc, folio);
 	if (ret)
 		goto out;
 
 	nfs_pageio_complete_read(&desc.pgio);
 	ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
 	if (!ret) {
-		ret = wait_on_page_locked_killable(page);
-		if (!PageUptodate(page) && !ret)
+		ret = folio_wait_locked_killable(folio);
+		if (!folio_test_uptodate(folio) && !ret)
 			ret = xchg(&desc.ctx->error, 0);
 	}
 out:
 	put_nfs_open_context(desc.ctx);
-	trace_nfs_aop_readpage_done(inode, page, ret);
+	trace_nfs_aop_readpage_done(inode, folio, ret);
 	return ret;
 out_unlock:
-	unlock_page(page);
-	trace_nfs_aop_readpage_done(inode, page, ret);
+	folio_unlock(folio);
+	trace_nfs_aop_readpage_done(inode, folio, ret);
 	return ret;
 }
 
@@ -395,7 +394,7 @@ void nfs_readahead(struct readahead_control *ractl)
 	struct file *file = ractl->file;
 	struct nfs_readdesc desc;
 	struct inode *inode = ractl->mapping->host;
-	struct page *page;
+	struct folio *folio;
 	int ret;
 
 	trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
@@ -416,9 +415,8 @@ void nfs_readahead(struct readahead_control *ractl)
 	nfs_pageio_init_read(&desc.pgio, inode, false,
 			     &nfs_async_read_completion_ops);
 
-	while ((page = readahead_page(ractl)) != NULL) {
-		ret = readpage_async_filler(&desc, page);
-		put_page(page);
+	while ((folio = readahead_folio(ractl)) != NULL) {
+		ret = readpage_async_filler(&desc, folio);
 		if (ret)
 			break;
 	}
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index b0b03ec4a209..3c71493d5cc3 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -125,6 +125,10 @@ extern	struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
 					    struct page *page,
 					    unsigned int offset,
 					    unsigned int count);
+extern struct nfs_page *nfs_page_create_from_folio(struct nfs_open_context *ctx,
+						   struct folio *folio,
+						   unsigned int offset,
+						   unsigned int count);
 extern	void nfs_release_request(struct nfs_page *);
 
 
-- 
2.39.0