new ->follow_link() and ->put_link() calling conventions

a) instead of storing the symlink body (via nd_set_link()) and returning
an opaque pointer later passed to ->put_link(), ->follow_link() _stores_
that opaque pointer (into void * passed by address by caller) and returns
the symlink body.  Returning ERR_PTR() on error, NULL on jump (procfs magic
symlinks) and pointer to symlink body for normal symlinks.  Stored pointer
is ignored in all cases except the last one.

Storing NULL for opaque pointer (or not storing it at all) means no call
of ->put_link().

b) the body used to be passed to ->put_link() implicitly (via nameidata).
Now only the opaque pointer is.  In the cases when we used the symlink body
to free stuff, ->follow_link() now should store it as opaque pointer in addition
to returning it.

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

1 files changed, 16 insertions, 19 deletions

diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c
index 172e306d68a7..3a1aefb86a11 100644
--- a/fs/befs/linuxvfs.c
+++ b/fs/befs/linuxvfs.c
@@ -42,7 +42,7 @@ static struct inode *befs_iget(struct super_block *, unsigned long);
 static struct inode *befs_alloc_inode(struct super_block *sb);
 static void befs_destroy_inode(struct inode *inode);
 static void befs_destroy_inodecache(void);
-static void *befs_follow_link(struct dentry *, struct nameidata *);
+static const char *befs_follow_link(struct dentry *, void **, struct nameidata *nd);
 static int befs_utf2nls(struct super_block *sb, const char *in, int in_len,
 			char **out, int *out_len);
 static int befs_nls2utf(struct super_block *sb, const char *in, int in_len,
@@ -463,8 +463,8 @@ befs_destroy_inodecache(void)
  * The data stream become link name. Unless the LONG_SYMLINK
  * flag is set.
  */
-static void *
-befs_follow_link(struct dentry *dentry, struct nameidata *nd)
+static const char *
+befs_follow_link(struct dentry *dentry, void **cookie, struct nameidata *nd)
 {
 	struct super_block *sb = dentry->d_sb;
 	struct befs_inode_info *befs_ino = BEFS_I(d_inode(dentry));
@@ -474,23 +474,20 @@ befs_follow_link(struct dentry *dentry, struct nameidata *nd)
 
 	if (len == 0) {
 		befs_error(sb, "Long symlink with illegal length");
-		link = ERR_PTR(-EIO);
-	} else {
-		befs_debug(sb, "Follow long symlink");
-
-		link = kmalloc(len, GFP_NOFS);
-		if (!link) {
-			link = ERR_PTR(-ENOMEM);
-		} else if (befs_read_lsymlink(sb, data, link, len) != len) {
-			kfree(link);
-			befs_error(sb, "Failed to read entire long symlink");
-			link = ERR_PTR(-EIO);
-		} else {
-			link[len - 1] = '\0';
-		}
+		return ERR_PTR(-EIO);
 	}
-	nd_set_link(nd, link);
-	return NULL;
+	befs_debug(sb, "Follow long symlink");
+
+	link = kmalloc(len, GFP_NOFS);
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	if (befs_read_lsymlink(sb, data, link, len) != len) {
+		kfree(link);
+		befs_error(sb, "Failed to read entire long symlink");
+		return ERR_PTR(-EIO);
+	}
+	link[len - 1] = '\0';
+	return *cookie = link;
 }
 
 /*