Merge tag '9p-6.4-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs

Pull 9p updates from Eric Van Hensbergen:
 "This includes a number of patches that didn't quite make the cut last
  merge window while we addressed some outstanding issues and review
  comments. It includes some new caching modes for those that only want
  readahead caches and reworks how we do writeback caching so we are not
  keeping extra references around which both causes performance problems
  and uses lots of additional resources on the server.

  It also includes a new flag to force disabling of xattrs which can
  also cause major performance issues, particularly if the underlying
  filesystem on the server doesn't support them.

  Finally it adds a couple of additional mount options to better support
  directio and enabling caches when the server doesn't support
  qid.version.

  There was one late-breaking bug report that has also been included as
  its own patch where I forgot to propagate an embarassing bit-logic fix
  to the various variations of open"

* tag '9p-6.4-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs:
  fs/9p: Fix bit operation logic error
  fs/9p: Rework cache modes and add new options to Documentation
  fs/9p: remove writeback fid and fix per-file modes
  fs/9p: Add new mount modes
  9p: Add additional debug flags and open modes
  fs/9p: allow disable of xattr support on mount
  fs/9p: Remove unnecessary superblock flags
  fs/9p: Consolidate file operations and add readahead and writeback

1 files changed, 28 insertions, 22 deletions

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 6f46d7e4c750..9239a049f736 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -57,8 +57,6 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
  */
 static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
 {
-	struct inode *inode = file_inode(file);
-	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct p9_fid *fid = file->private_data;
 
 	BUG_ON(!fid);
@@ -66,11 +64,8 @@ static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
 	/* we might need to read from a fid that was opened write-only
 	 * for read-modify-write of page cache, use the writeback fid
 	 * for that */
-	if (rreq->origin == NETFS_READ_FOR_WRITE &&
-			(fid->mode & O_ACCMODE) == O_WRONLY) {
-		fid = v9inode->writeback_fid;
-		BUG_ON(!fid);
-	}
+	WARN_ON(rreq->origin == NETFS_READ_FOR_WRITE &&
+			!(fid->mode & P9_ORDWR));
 
 	p9_fid_get(fid);
 	rreq->netfs_priv = fid;
@@ -120,8 +115,6 @@ const struct netfs_request_ops v9fs_req_ops = {
 
 static bool v9fs_release_folio(struct folio *folio, gfp_t gfp)
 {
-	struct inode *inode = folio_inode(folio);
-
 	if (folio_test_private(folio))
 		return false;
 #ifdef CONFIG_9P_FSCACHE
@@ -130,8 +123,8 @@ static bool v9fs_release_folio(struct folio *folio, gfp_t gfp)
 			return false;
 		folio_wait_fscache(folio);
 	}
+	fscache_note_page_release(v9fs_inode_cookie(V9FS_I(folio_inode(folio))));
 #endif
-	fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode)));
 	return true;
 }
 
@@ -141,6 +134,7 @@ static void v9fs_invalidate_folio(struct folio *folio, size_t offset,
 	folio_wait_fscache(folio);
 }
 
+#ifdef CONFIG_9P_FSCACHE
 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
 				     bool was_async)
 {
@@ -154,17 +148,19 @@ static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
 				   i_size_read(&v9inode->netfs.inode), 0);
 	}
 }
+#endif
 
 static int v9fs_vfs_write_folio_locked(struct folio *folio)
 {
 	struct inode *inode = folio_inode(folio);
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-	struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode);
 	loff_t start = folio_pos(folio);
 	loff_t i_size = i_size_read(inode);
 	struct iov_iter from;
 	size_t len = folio_size(folio);
+	struct p9_fid *writeback_fid;
 	int err;
+	struct v9fs_inode __maybe_unused *v9inode = V9FS_I(inode);
+	struct fscache_cookie __maybe_unused *cookie = v9fs_inode_cookie(v9inode);
 
 	if (start >= i_size)
 		return 0; /* Simultaneous truncation occurred */
@@ -173,25 +169,33 @@ static int v9fs_vfs_write_folio_locked(struct folio *folio)
 
 	iov_iter_xarray(&from, ITER_SOURCE, &folio_mapping(folio)->i_pages, start, len);
 
-	/* We should have writeback_fid always set */
-	BUG_ON(!v9inode->writeback_fid);
+	writeback_fid = v9fs_fid_find_inode(inode, true, INVALID_UID, true);
+	if (!writeback_fid) {
+		WARN_ONCE(1, "folio expected an open fid inode->i_private=%p\n",
+			inode->i_private);
+		return -EINVAL;
+	}
 
 	folio_wait_fscache(folio);
 	folio_start_writeback(folio);
 
-	p9_client_write(v9inode->writeback_fid, start, &from, &err);
+	p9_client_write(writeback_fid, start, &from, &err);
 
+#ifdef CONFIG_9P_FSCACHE
 	if (err == 0 &&
-	    fscache_cookie_enabled(cookie) &&
-	    test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) {
+		fscache_cookie_enabled(cookie) &&
+		test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) {
 		folio_start_fscache(folio);
 		fscache_write_to_cache(v9fs_inode_cookie(v9inode),
-				       folio_mapping(folio), start, len, i_size,
-				       v9fs_write_to_cache_done, v9inode,
-				       true);
+					folio_mapping(folio), start, len, i_size,
+					v9fs_write_to_cache_done, v9inode,
+					true);
 	}
+#endif
 
 	folio_end_writeback(folio);
+	p9_fid_put(writeback_fid);
+
 	return err;
 }
 
@@ -298,7 +302,6 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 	loff_t last_pos = pos + copied;
 	struct folio *folio = page_folio(subpage);
 	struct inode *inode = mapping->host;
-	struct v9fs_inode *v9inode = V9FS_I(inode);
 
 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
 
@@ -318,7 +321,10 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 	if (last_pos > inode->i_size) {
 		inode_add_bytes(inode, last_pos - inode->i_size);
 		i_size_write(inode, last_pos);
-		fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos);
+#ifdef CONFIG_9P_FSCACHE
+		fscache_update_cookie(v9fs_inode_cookie(V9FS_I(inode)), NULL,
+			&last_pos);
+#endif
 	}
 	folio_mark_dirty(folio);
 out: