netfs: Further cleanups after struct netfs_inode wrapper introduced

Change the signature of netfs helper functions to take a struct netfs_inode
pointer rather than a struct inode pointer where appropriate, thereby
relieving the need for the network filesystem to convert its internal inode
format down to the VFS inode only for netfslib to bounce it back up.  For
type safety, it's better not to do that (and it's less typing too).

Give netfs_write_begin() an extra argument to pass in a pointer to the
netfs_inode struct rather than deriving it internally from the file
pointer.  Note that the ->write_begin() and ->write_end() ops are intended
to be replaced in the future by netfslib code that manages this without the
need to call in twice for each page.

netfs_readpage() and similar are intended to be pointed at directly by the
address_space_operations table, so must stick to the signature dictated by
the function pointers there.

Changes
=======
- Updated the kerneldoc comments and documentation [DH].

Signed-off-by: David Howells <[email protected]>
cc: [email protected]
Link: https://lore.kernel.org/r/CAHk-=wgkwKyNmNdKpQkqZ6DnmUL-x9hp0YBnUGjaPFEAdxDTbw@mail.gmail.com/

Author: torvalds

Documentation/filesystems/netfs_library.rst

@@ -79,7 +79,7 @@ To help deal with the per-inode context, a number helper functions are
 provided.  Firstly, a function to perform basic initialisation on a context and
 set the operations table pointer::
 
-	void netfs_inode_init(struct inode *inode,
+	void netfs_inode_init(struct netfs_inode *ctx,
 			      const struct netfs_request_ops *ops);
 
 then a function to cast from the VFS inode structure to the netfs context::
@@ -89,7 +89,7 @@ then a function to cast from the VFS inode structure to the netfs context::
 and finally, a function to get the cache cookie pointer from the context
 attached to an inode (or NULL if fscache is disabled)::
 
-	struct fscache_cookie *netfs_i_cookie(struct inode *inode);
+	struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx);
 
 
 Buffered Read Helpers
@@ -136,8 +136,9 @@ Three read helpers are provided::
 
 	void netfs_readahead(struct readahead_control *ractl);
 	int netfs_read_folio(struct file *file,
-			   struct folio *folio);
-	int netfs_write_begin(struct file *file,
+			     struct folio *folio);
+	int netfs_write_begin(struct netfs_inode *ctx,
+			      struct file *file,
 			      struct address_space *mapping,
 			      loff_t pos,
 			      unsigned int len,

fs/9p/v9fs.h

@@ -124,7 +124,7 @@ static inline struct v9fs_inode *V9FS_I(const struct inode *inode)
 static inline struct fscache_cookie *v9fs_inode_cookie(struct v9fs_inode *v9inode)
 {
 #ifdef CONFIG_9P_FSCACHE
-	return netfs_i_cookie(&v9inode->netfs.inode);
+	return netfs_i_cookie(&v9inode->netfs);
 #else
 	return NULL;
 #endif

fs/9p/vfs_addr.c

@@ -274,7 +274,7 @@ static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
 	 * file.  We need to do this before we get a lock on the page in case
 	 * there's more than one writer competing for the same cache block.
 	 */
-	retval = netfs_write_begin(filp, mapping, pos, len, &folio, fsdata);
+	retval = netfs_write_begin(&v9inode->netfs, filp, mapping, pos, len, &folio, fsdata);
 	if (retval < 0)
 		return retval;
 

fs/9p/vfs_inode.c

@@ -252,7 +252,8 @@ void v9fs_free_inode(struct inode *inode)
  */
 static void v9fs_set_netfs_context(struct inode *inode)
 {
-	netfs_inode_init(inode, &v9fs_req_ops);
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	netfs_inode_init(&v9inode->netfs, &v9fs_req_ops);
 }
 
 int v9fs_init_inode(struct v9fs_session_info *v9ses,

fs/afs/dynroot.c

@@ -76,7 +76,7 @@ struct inode *afs_iget_pseudo_dir(struct super_block *sb, bool root)
 	/* there shouldn't be an existing inode */
 	BUG_ON(!(inode->i_state & I_NEW));
 
-	netfs_inode_init(inode, NULL);
+	netfs_inode_init(&vnode->netfs, NULL);
 	inode->i_size		= 0;
 	inode->i_mode		= S_IFDIR | S_IRUGO | S_IXUGO;
 	if (root) {

fs/afs/inode.c

@@ -58,7 +58,7 @@ static noinline void dump_vnode(struct afs_vnode *vnode, struct afs_vnode *paren
  */
 static void afs_set_netfs_context(struct afs_vnode *vnode)
 {
-	netfs_inode_init(&vnode->netfs.inode, &afs_req_ops);
+	netfs_inode_init(&vnode->netfs, &afs_req_ops);
 }
 
 /*

fs/afs/internal.h

@@ -670,7 +670,7 @@ struct afs_vnode {
 static inline struct fscache_cookie *afs_vnode_cache(struct afs_vnode *vnode)
 {
 #ifdef CONFIG_AFS_FSCACHE
-	return netfs_i_cookie(&vnode->netfs.inode);
+	return netfs_i_cookie(&vnode->netfs);
 #else
 	return NULL;
 #endif

fs/afs/write.c

@@ -60,7 +60,7 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 	 * file.  We need to do this before we get a lock on the page in case
 	 * there's more than one writer competing for the same cache block.
 	 */
-	ret = netfs_write_begin(file, mapping, pos, len, &folio, fsdata);
+	ret = netfs_write_begin(&vnode->netfs, file, mapping, pos, len, &folio, fsdata);
 	if (ret < 0)
 		return ret;
 

fs/ceph/addr.c

@@ -1322,10 +1322,11 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping,
 			    struct page **pagep, void **fsdata)
 {
 	struct inode *inode = file_inode(file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct folio *folio = NULL;
 	int r;
 
-	r = netfs_write_begin(file, inode->i_mapping, pos, len, &folio, NULL);
+	r = netfs_write_begin(&ci->netfs, file, inode->i_mapping, pos, len, &folio, NULL);
 	if (r == 0)
 		folio_wait_fscache(folio);
 	if (r < 0) {

fs/ceph/cache.h

@@ -28,7 +28,7 @@ void ceph_fscache_invalidate(struct inode *inode, bool dio_write);
 
 static inline struct fscache_cookie *ceph_fscache_cookie(struct ceph_inode_info *ci)
 {
-	return netfs_i_cookie(&ci->netfs.inode);
+	return netfs_i_cookie(&ci->netfs);
 }
 
 static inline void ceph_fscache_resize(struct inode *inode, loff_t to)