switch ->get_link() to delayed_call, kill ->put_link()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Documentation/filesystems/Locking

@@ -51,7 +51,6 @@ prototypes:
 			struct inode *, struct dentry *, unsigned int);
 	int (*readlink) (struct dentry *, char __user *,int);
 	const char *(*get_link) (struct dentry *, struct inode *, void **);
-	void (*put_link) (struct inode *, void *);
 	void (*truncate) (struct inode *);
 	int (*permission) (struct inode *, int, unsigned int);
 	int (*get_acl)(struct inode *, int);
@@ -84,7 +83,6 @@ rename:		yes (all)	(see below)
 rename2:	yes (all)	(see below)
 readlink:	no
 get_link:	no
-put_link:	no
 setattr:	yes
 permission:	no (may not block if called in rcu-walk mode)
 get_acl:	no

Documentation/filesystems/porting

@@ -515,3 +515,9 @@ in your dentry operations instead.
 		* ->get_link() gets inode as a separate argument
 		* ->get_link() may be called in RCU mode - in that case NULL
 		  dentry is passed
+--
+[mandatory]
+	->get_link() gets struct delayed_call *done now, and should do
+	set_delayed_call() where it used to set *cookie.
+	->put_link() is gone - just give the destructor to set_delayed_call()
+	in ->get_link().

Documentation/filesystems/vfs.txt

@@ -350,8 +350,8 @@ struct inode_operations {
 	int (*rename2) (struct inode *, struct dentry *,
 			struct inode *, struct dentry *, unsigned int);
 	int (*readlink) (struct dentry *, char __user *,int);
-	const char *(*follow_link) (struct dentry *, void **);
-	void (*put_link) (struct inode *, void *);
+	const char *(*get_link) (struct dentry *, struct inode *,
+				 struct delayed_call *);
 	int (*permission) (struct inode *, int);
 	int (*get_acl)(struct inode *, int);
 	int (*setattr) (struct dentry *, struct iattr *);
@@ -434,20 +434,19 @@ otherwise noted.
   readlink: called by the readlink(2) system call. Only required if
 	you want to support reading symbolic links
 
-  follow_link: called by the VFS to follow a symbolic link to the
+  get_link: called by the VFS to follow a symbolic link to the
 	inode it points to.  Only required if you want to support
 	symbolic links.  This method returns the symlink body
 	to traverse (and possibly resets the current position with
 	nd_jump_link()).  If the body won't go away until the inode
 	is gone, nothing else is needed; if it needs to be otherwise
-	pinned, the data needed to release whatever we'd grabbed
-	is to be stored in void * variable passed by address to
-	follow_link() instance.
-
-  put_link: called by the VFS to release resources allocated by
-	follow_link().  The cookie stored by follow_link() is passed
-	to this method as the last parameter; only called when
-	cookie isn't NULL.
+	pinned, arrange for its release by having get_link(..., ..., done)
+	do set_delayed_call(done, destructor, argument).
+	In that case destructor(argument) will be called once VFS is
+	done with the body you've returned.
+	May be called in RCU mode; that is indicated by NULL dentry
+	argument.  If request can't be handled without leaving RCU mode,
+	have it return ERR_PTR(-ECHILD).
 
   permission: called by the VFS to check for access rights on a POSIX-like
   	filesystem.

drivers/staging/lustre/lustre/llite/symlink.c

@@ -118,8 +118,14 @@ failed:
 	return rc;
 }
 
+static void ll_put_link(void *p)
+{
+	ptlrpc_req_finished(p);
+}
+
 static const char *ll_get_link(struct dentry *dentry,
-			       struct inode *inode, void **cookie)
+			       struct inode *inode,
+			       struct delayed_call *done)
 {
 	struct ptlrpc_request *request = NULL;
 	int rc;
@@ -137,22 +143,16 @@ static const char *ll_get_link(struct dentry *dentry,
 	}
 
 	/* symname may contain a pointer to the request message buffer,
-	 * we delay request releasing until ll_put_link then.
+	 * we delay request releasing then.
 	 */
-	*cookie = request;
+	set_delayed_call(done, ll_put_link, request);
 	return symname;
 }
 
-static void ll_put_link(struct inode *unused, void *cookie)
-{
-	ptlrpc_req_finished(cookie);
-}
-
 struct inode_operations ll_fast_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.setattr	= ll_setattr,
 	.get_link	= ll_get_link,
-	.put_link	= ll_put_link,
 	.getattr	= ll_getattr,
 	.permission	= ll_inode_permission,
 	.setxattr	= ll_setxattr,

fs/9p/vfs_inode.c

@@ -1226,11 +1226,12 @@ ino_t v9fs_qid2ino(struct p9_qid *qid)
  * v9fs_vfs_get_link - follow a symlink path
  * @dentry: dentry for symlink
  * @inode: inode for symlink
- * @cookie: place to pass the data to put_link()
+ * @done: delayed call for when we are done with the return value
  */
 
 static const char *v9fs_vfs_get_link(struct dentry *dentry,
-				     struct inode *inode, void **cookie)
+				     struct inode *inode,
+				     struct delayed_call *done)
 {
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid;
@@ -1266,7 +1267,8 @@ static const char *v9fs_vfs_get_link(struct dentry *dentry,
 
 	p9stat_free(st);
 	kfree(st);
-	return *cookie = res;
+	set_delayed_call(done, kfree_link, res);
+	return res;
 }
 
 /**
@@ -1460,7 +1462,6 @@ static const struct inode_operations v9fs_file_inode_operations = {
 static const struct inode_operations v9fs_symlink_inode_operations = {
 	.readlink = generic_readlink,
 	.get_link = v9fs_vfs_get_link,
-	.put_link = kfree_put_link,
 	.getattr = v9fs_vfs_getattr,
 	.setattr = v9fs_vfs_setattr,
 };

fs/9p/vfs_inode_dotl.c

@@ -902,12 +902,13 @@ error:
  * v9fs_vfs_get_link_dotl - follow a symlink path
  * @dentry: dentry for symlink
  * @inode: inode for symlink
- * @cookie: place to pass the data to put_link()
+ * @done: destructor for return value
  */
 
 static const char *
 v9fs_vfs_get_link_dotl(struct dentry *dentry,
-		       struct inode *inode, void **cookie)
+		       struct inode *inode,
+		       struct delayed_call *done)
 {
 	struct p9_fid *fid;
 	char *target;
@@ -924,7 +925,8 @@ v9fs_vfs_get_link_dotl(struct dentry *dentry,
 	retval = p9_client_readlink(fid, &target);
 	if (retval)
 		return ERR_PTR(retval);
-	return *cookie = target;
+	set_delayed_call(done, kfree_link, target);
+	return target;
 }
 
 int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
@@ -991,7 +993,6 @@ const struct inode_operations v9fs_file_inode_operations_dotl = {
 const struct inode_operations v9fs_symlink_inode_operations_dotl = {
 	.readlink = generic_readlink,
 	.get_link = v9fs_vfs_get_link_dotl,
-	.put_link = kfree_put_link,
 	.getattr = v9fs_vfs_getattr_dotl,
 	.setattr = v9fs_vfs_setattr_dotl,
 	.setxattr = generic_setxattr,

fs/affs/symlink.c

@@ -72,6 +72,5 @@ const struct address_space_operations affs_symlink_aops = {
 const struct inode_operations affs_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
-	.put_link	= page_put_link,
 	.setattr	= affs_notify_change,
 };

fs/autofs4/symlink.c

@@ -13,7 +13,8 @@
 #include "autofs_i.h"
 
 static const char *autofs4_get_link(struct dentry *dentry,
-				    struct inode *inode, void **cookie)
+				    struct inode *inode,
+				    struct delayed_call *done)
 {
 	struct autofs_sb_info *sbi;
 	struct autofs_info *ino;

fs/btrfs/inode.c

@@ -10097,7 +10097,6 @@ static const struct inode_operations btrfs_special_inode_operations = {
 static const struct inode_operations btrfs_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
-	.put_link	= page_put_link,
 	.getattr	= btrfs_getattr,
 	.setattr	= btrfs_setattr,
 	.permission	= btrfs_permission,

fs/cifs/cifsfs.c

@@ -901,7 +901,6 @@ const struct inode_operations cifs_file_inode_ops = {
 const struct inode_operations cifs_symlink_inode_ops = {
 	.readlink = generic_readlink,
 	.get_link = cifs_get_link,
-	.put_link = kfree_put_link,
 	.permission = cifs_permission,
 	/* BB add the following two eventually */
 	/* revalidate: cifs_revalidate,

fs/cifs/cifsfs.h

@@ -120,7 +120,8 @@ extern struct vfsmount *cifs_dfs_d_automount(struct path *path);
 #endif
 
 /* Functions related to symlinks */
-extern const char *cifs_get_link(struct dentry *, struct inode *, void **);
+extern const char *cifs_get_link(struct dentry *, struct inode *,
+			struct delayed_call *);
 extern int cifs_symlink(struct inode *inode, struct dentry *direntry,
 			const char *symname);
 extern int	cifs_removexattr(struct dentry *, const char *);

fs/cifs/link.c

@@ -627,7 +627,8 @@ cifs_hl_exit:
 }
 
 const char *
-cifs_get_link(struct dentry *direntry, struct inode *inode, void **cookie)
+cifs_get_link(struct dentry *direntry, struct inode *inode,
+	      struct delayed_call *done)
 {
 	int rc = -ENOMEM;
 	unsigned int xid;
@@ -680,7 +681,8 @@ cifs_get_link(struct dentry *direntry, struct inode *inode, void **cookie)
 		kfree(target_path);
 		return ERR_PTR(rc);
 	}
-	return *cookie = target_path;
+	set_delayed_call(done, kfree_link, target_path);
+	return target_path;
 }
 
 int

fs/coda/cnode.c

@@ -19,7 +19,6 @@ static inline int coda_fideq(struct CodaFid *fid1, struct CodaFid *fid2)
 static const struct inode_operations coda_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
-	.put_link	= page_put_link,
 	.setattr	= coda_setattr,
 };
 

fs/configfs/symlink.c

@@ -280,31 +280,32 @@ static int configfs_getlink(struct dentry *dentry, char * path)
 }
 
 static const char *configfs_get_link(struct dentry *dentry,
-				     struct inode *inode, void **cookie)
+				     struct inode *inode,
+				     struct delayed_call *done)
 {
-	char *page;
+	char *body;
 	int error;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
 
-	page = kzalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!page)
+	body = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!body)
 		return ERR_PTR(-ENOMEM);
 
-	error = configfs_getlink(dentry, page);
+	error = configfs_getlink(dentry, body);
 	if (!error) {
-		return *cookie = page;
+		set_delayed_call(done, kfree_link, body);
+		return body;
 	}
 
-	kfree(page);
+	kfree(body);
 	return ERR_PTR(error);
 }
 
 const struct inode_operations configfs_symlink_inode_operations = {
 	.get_link = configfs_get_link,
 	.readlink = generic_readlink,
-	.put_link = kfree_put_link,
 	.setattr = configfs_setattr,
 };
 

fs/ecryptfs/inode.c

@@ -675,7 +675,8 @@ out:
 }
 
 static const char *ecryptfs_get_link(struct dentry *dentry,
-				     struct inode *inode, void **cookie)
+				     struct inode *inode,
+				     struct delayed_call *done)
 {
 	size_t len;
 	char *buf;
@@ -689,7 +690,8 @@ static const char *ecryptfs_get_link(struct dentry *dentry,
 	fsstack_copy_attr_atime(d_inode(dentry),
 				d_inode(ecryptfs_dentry_to_lower(dentry)));
 	buf[len] = '\0';
-	return *cookie = buf;
+	set_delayed_call(done, kfree_link, buf);
+	return buf;
 }
 
 /**
@@ -1102,7 +1104,6 @@ out:
 const struct inode_operations ecryptfs_symlink_iops = {
 	.readlink = generic_readlink,
 	.get_link = ecryptfs_get_link,
-	.put_link = kfree_put_link,
 	.permission = ecryptfs_permission,
 	.setattr = ecryptfs_setattr,
 	.getattr = ecryptfs_getattr_link,

fs/ext2/symlink.c

@@ -23,7 +23,6 @@
 const struct inode_operations ext2_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
-	.put_link	= page_put_link,
 	.setattr	= ext2_setattr,
 #ifdef CONFIG_EXT2_FS_XATTR
 	.setxattr	= generic_setxattr,

fs/ext4/symlink.c

@@ -24,7 +24,8 @@
 
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 static const char *ext4_encrypted_get_link(struct dentry *dentry,
-					   struct inode *inode, void **cookie)
+					   struct inode *inode,
+					   struct delayed_call *done)
 {
 	struct page *cpage = NULL;
 	char *caddr, *paddr = NULL;
@@ -80,7 +81,8 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
 		paddr[res] = '\0';
 	if (cpage)
 		page_cache_release(cpage);
-	return *cookie = paddr;
+	set_delayed_call(done, kfree_link, paddr);
+	return paddr;
 errout:
 	if (cpage)
 		page_cache_release(cpage);
@@ -91,7 +93,6 @@ errout:
 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.get_link	= ext4_encrypted_get_link,
-	.put_link       = kfree_put_link,
 	.setattr	= ext4_setattr,
 	.setxattr	= generic_setxattr,
 	.getxattr	= generic_getxattr,
@@ -103,7 +104,6 @@ const struct inode_operations ext4_encrypted_symlink_inode_operations = {
 const struct inode_operations ext4_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.get_link	= page_get_link,
-	.put_link	= page_put_link,
 	.setattr	= ext4_setattr,
 	.setxattr	= generic_setxattr,
 	.getxattr	= generic_getxattr,

fs/f2fs/namei.c

@@ -316,12 +316,14 @@ fail:
 }
 
 static const char *f2fs_get_link(struct dentry *dentry,
-				 struct inode *inode, void **cookie)
+				 struct inode *inode,
+				 struct delayed_call *done)
 {
-	const char *link = page_get_link(dentry, inode, cookie);
+	const char *link = page_get_link(dentry, inode, done);
 	if (!IS_ERR(link) && !*link) {
 		/* this is broken symlink case */
-		page_put_link(NULL, *cookie);
+		do_delayed_call(done);
+		clear_delayed_call(done);
 		link = ERR_PTR(-ENOENT);
 	}
 	return link;
@@ -926,7 +928,8 @@ static int f2fs_rename2(struct inode *old_dir, struct dentry *old_dentry,
 
 #ifdef CONFIG_F2FS_FS_ENCRYPTION
 static const char *f2fs_encrypted_get_link(struct dentry *dentry,
-					   struct inode *inode, void **cookie)
+					   struct inode *inode,
+					   struct delayed_call *done)
 {
 	struct page *cpage = NULL;
 	char *caddr, *paddr = NULL;
@@ -988,7 +991,8 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
 	paddr[res] = '\0';
 
 	page_cache_release(cpage);
-	return *cookie = paddr;
+	set_delayed_call(done, kfree_link, paddr);
+	return paddr;
 errout:
 	kfree(cstr.name);
 	f2fs_fname_crypto_free_buffer(&pstr);
@@ -999,7 +1003,6 @@ errout:
 const struct inode_operations f2fs_encrypted_symlink_inode_operations = {
 	.readlink       = generic_readlink,
 	.get_link       = f2fs_encrypted_get_link,
-	.put_link       = kfree_put_link,
 	.getattr	= f2fs_getattr,
 	.setattr	= f2fs_setattr,
 	.setxattr	= generic_setxattr,
@@ -1035,7 +1038,6 @@ const struct inode_operations f2fs_dir_inode_operations = {
 const struct inode_operations f2fs_symlink_inode_operations = {
 	.readlink       = generic_readlink,
 	.get_link       = f2fs_get_link,
-	.put_link       = page_put_link,
 	.getattr	= f2fs_getattr,
 	.setattr	= f2fs_setattr,
 #ifdef CONFIG_F2FS_FS_XATTR

fs/fuse/dir.c

@@ -1366,7 +1366,8 @@ static int fuse_readdir(struct file *file, struct dir_context *ctx)
 }
 
 static const char *fuse_get_link(struct dentry *dentry,
-				 struct inode *inode, void **cookie)
+				 struct inode *inode,
+				 struct delayed_call *done)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	FUSE_ARGS(args);
@@ -1392,7 +1393,7 @@ static const char *fuse_get_link(struct dentry *dentry,
 		link = ERR_PTR(ret);
 	} else {
 		link[ret] = '\0';
-		*cookie = link;
+		set_delayed_call(done, kfree_link, link);
 	}
 	fuse_invalidate_atime(inode);
 	return link;
@@ -1913,7 +1914,6 @@ static const struct inode_operations fuse_common_inode_operations = {
 static const struct inode_operations fuse_symlink_inode_operations = {
 	.setattr	= fuse_setattr,
 	.get_link	= fuse_get_link,
-	.put_link	= kfree_put_link,
 	.readlink	= generic_readlink,
 	.getattr	= fuse_getattr,
 	.setxattr	= fuse_setxattr,

fs/gfs2/inode.c

@@ -1715,7 +1715,7 @@ static int gfs2_rename2(struct inode *odir, struct dentry *odentry,
  * gfs2_get_link - Follow a symbolic link
  * @dentry: The dentry of the link
  * @inode: The inode of the link
- * @cookie: place to store the information for ->put_link()
+ * @done: destructor for return value
  *
  * This can handle symlinks of any size.
  *
@@ -1723,7 +1723,8 @@ static int gfs2_rename2(struct inode *odir, struct dentry *odentry,
  */
 
 static const char *gfs2_get_link(struct dentry *dentry,
-				 struct inode *inode, void **cookie)
+				 struct inode *inode,
+				 struct delayed_call *done)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_holder i_gh;
@@ -1764,7 +1765,7 @@ static const char *gfs2_get_link(struct dentry *dentry,
 out:
 	gfs2_glock_dq_uninit(&i_gh);
 	if (!IS_ERR(buf))
-		*cookie = buf;
+		set_delayed_call(done, kfree_link, buf);
 	return buf;
 }
 
@@ -2138,7 +2139,6 @@ const struct inode_operations gfs2_dir_iops = {
 const struct inode_operations gfs2_symlink_iops = {
 	.readlink = generic_readlink,
 	.get_link = gfs2_get_link,
-	.put_link = kfree_put_link,
 	.permission = gfs2_permission,
 	.setattr = gfs2_setattr,
 	.getattr = gfs2_getattr,