nfs: Convert nfs_symlink() to use a folio

Use the folio APIs, saving about four calls to compound_head().
Convert back to a page in each of the individual protocol implementations.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/dir.c

@@ -2532,7 +2532,7 @@ EXPORT_SYMBOL_GPL(nfs_unlink);
 int nfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 		struct dentry *dentry, const char *symname)
 {
-	struct page *page;
+	struct folio *folio;
 	char *kaddr;
 	struct iattr attr;
 	unsigned int pathlen = strlen(symname);
@@ -2547,24 +2547,24 @@ int nfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	attr.ia_mode = S_IFLNK | S_IRWXUGO;
 	attr.ia_valid = ATTR_MODE;
 
-	page = alloc_page(GFP_USER);
-	if (!page)
+	folio = folio_alloc(GFP_USER, 0);
+	if (!folio)
 		return -ENOMEM;
 
-	kaddr = page_address(page);
+	kaddr = folio_address(folio);
 	memcpy(kaddr, symname, pathlen);
 	if (pathlen < PAGE_SIZE)
 		memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
 
 	trace_nfs_symlink_enter(dir, dentry);
-	error = NFS_PROTO(dir)->symlink(dir, dentry, page, pathlen, &attr);
+	error = NFS_PROTO(dir)->symlink(dir, dentry, folio, pathlen, &attr);
 	trace_nfs_symlink_exit(dir, dentry, error);
 	if (error != 0) {
 		dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s) error %d\n",
 			dir->i_sb->s_id, dir->i_ino,
 			dentry, symname, error);
 		d_drop(dentry);
-		__free_page(page);
+		folio_put(folio);
 		return error;
 	}
 
@@ -2574,18 +2574,13 @@ int nfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	 * No big deal if we can't add this page to the page cache here.
 	 * READLINK will get the missing page from the server if needed.
 	 */
-	if (!add_to_page_cache_lru(page, d_inode(dentry)->i_mapping, 0,
-							GFP_KERNEL)) {
-		SetPageUptodate(page);
-		unlock_page(page);
-		/*
-		 * add_to_page_cache_lru() grabs an extra page refcount.
-		 * Drop it here to avoid leaking this page later.
-		 */
-		put_page(page);
-	} else
-		__free_page(page);
+	if (filemap_add_folio(d_inode(dentry)->i_mapping, folio, 0,
+							GFP_KERNEL) == 0) {
+		folio_mark_uptodate(folio);
+		folio_unlock(folio);
+	}
 
+	folio_put(folio);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(nfs_symlink);

fs/nfs/nfs3proc.c

@@ -543,9 +543,10 @@ nfs3_proc_link(struct inode *inode, struct inode *dir, const struct qstr *name)
 }
 
 static int
-nfs3_proc_symlink(struct inode *dir, struct dentry *dentry, struct page *page,
+nfs3_proc_symlink(struct inode *dir, struct dentry *dentry, struct folio *folio,
 		  unsigned int len, struct iattr *sattr)
 {
+	struct page *page = &folio->page;
 	struct nfs3_createdata *data;
 	struct dentry *d_alias;
 	int status = -ENOMEM;

fs/nfs/nfs4proc.c

@@ -5036,9 +5036,10 @@ static void nfs4_free_createdata(struct nfs4_createdata *data)
 }
 
 static int _nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
-		struct page *page, unsigned int len, struct iattr *sattr,
+		struct folio *folio, unsigned int len, struct iattr *sattr,
 		struct nfs4_label *label)
 {
+	struct page *page = &folio->page;
 	struct nfs4_createdata *data;
 	int status = -ENAMETOOLONG;
 
@@ -5063,7 +5064,7 @@ static int _nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
 }
 
 static int nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
-		struct page *page, unsigned int len, struct iattr *sattr)
+		struct folio *folio, unsigned int len, struct iattr *sattr)
 {
 	struct nfs4_exception exception = {
 		.interruptible = true,
@@ -5074,7 +5075,7 @@ static int nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
 	label = nfs4_label_init_security(dir, dentry, sattr, &l);
 
 	do {
-		err = _nfs4_proc_symlink(dir, dentry, page, len, sattr, label);
+		err = _nfs4_proc_symlink(dir, dentry, folio, len, sattr, label);
 		trace_nfs4_symlink(dir, &dentry->d_name, err);
 		err = nfs4_handle_exception(NFS_SERVER(dir), err,
 				&exception);

fs/nfs/proc.c

@@ -396,9 +396,10 @@ nfs_proc_link(struct inode *inode, struct inode *dir, const struct qstr *name)
 }
 
 static int
-nfs_proc_symlink(struct inode *dir, struct dentry *dentry, struct page *page,
+nfs_proc_symlink(struct inode *dir, struct dentry *dentry, struct folio *folio,
 		 unsigned int len, struct iattr *sattr)
 {
+	struct page *page = &folio->page;
 	struct nfs_fh *fh;
 	struct nfs_fattr *fattr;
 	struct nfs_symlinkargs	arg = {

include/linux/nfs_xdr.h

@@ -1772,7 +1772,7 @@ struct nfs_rpc_ops {
 	void	(*rename_rpc_prepare)(struct rpc_task *task, struct nfs_renamedata *);
 	int	(*rename_done) (struct rpc_task *task, struct inode *old_dir, struct inode *new_dir);
 	int	(*link)    (struct inode *, struct inode *, const struct qstr *);
-	int	(*symlink) (struct inode *, struct dentry *, struct page *,
+	int	(*symlink) (struct inode *, struct dentry *, struct folio *,
 			    unsigned int, struct iattr *);
 	int	(*mkdir)   (struct inode *, struct dentry *, struct iattr *);
 	int	(*rmdir)   (struct inode *, const struct qstr *);