[GFS2] Fix bug in directory code and tidy up

Due to a typo, the dir leaf split operation was (for the first
split in a directory) writing the new hash vaules at the
wrong offset. This is now fixed.

Also some other tidy ups are included:

 - We use GFS2's hash function for dentries (see ops_dentry.c) so that
   we don't have to keep recalculating the hash values.
 - A lot of common code is eliminated between the various directory
   lookup routines.
 - Better error checking on directory lookup (previously different
   routines checked for different errors)
 - The leaf split operation has a couple of redundant operations
   removed from it, so it should be faster.

There is still further scope for further clean ups in the directory
code, and readdir in particular could do with slimming down a bit.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/dir.h b/fs/gfs2/dir.h
index 5b01497..8fd4dc0 100644
--- a/fs/gfs2/dir.h
+++ b/fs/gfs2/dir.h
@@ -27,25 +27,34 @@
 			      uint64_t offset,
 			      struct gfs2_inum *inum, unsigned int type);
 
-int gfs2_filecmp(struct qstr *file1, char *file2, int len_of_file2);
-int gfs2_dirent_alloc(struct gfs2_inode *dip, struct buffer_head *bh,
-		     int name_len, struct gfs2_dirent **dent_out);
-
-int gfs2_dir_search(struct gfs2_inode *dip, struct qstr *filename,
-		   struct gfs2_inum *inum, unsigned int *type);
-int gfs2_dir_add(struct gfs2_inode *dip, struct qstr *filename,
-		struct gfs2_inum *inum, unsigned int type);
-int gfs2_dir_del(struct gfs2_inode *dip, struct qstr *filename);
+int gfs2_dir_search(struct inode *dir, const struct qstr *filename,
+		    struct gfs2_inum *inum, unsigned int *type);
+int gfs2_dir_add(struct inode *inode, const struct qstr *filename,
+		 const struct gfs2_inum *inum, unsigned int type);
+int gfs2_dir_del(struct gfs2_inode *dip, const struct qstr *filename);
 int gfs2_dir_read(struct gfs2_inode *dip, uint64_t * offset, void *opaque,
-		 gfs2_filldir_t filldir);
-int gfs2_dir_mvino(struct gfs2_inode *dip, struct qstr *filename,
-		  struct gfs2_inum *new_inum, unsigned int new_type);
+		  gfs2_filldir_t filldir);
+int gfs2_dir_mvino(struct gfs2_inode *dip, const struct qstr *filename,
+		   struct gfs2_inum *new_inum, unsigned int new_type);
 
 int gfs2_dir_exhash_dealloc(struct gfs2_inode *dip);
 
-int gfs2_diradd_alloc_required(struct gfs2_inode *dip, struct qstr *filename,
-			      int *alloc_required);
+int gfs2_diradd_alloc_required(struct inode *dir,
+			       const struct qstr *filename);
 int gfs2_dir_get_buffer(struct gfs2_inode *ip, uint64_t block, int new,
-                         struct buffer_head **bhp);
+                        struct buffer_head **bhp);
+
+/* N.B. This probably ought to take inum & type as args as well */
+static inline void gfs2_qstr2dirent(const struct qstr *name, u16 reclen, struct gfs2_dirent *dent)
+{
+	dent->de_inum.no_addr = cpu_to_be64(0);
+	dent->de_inum.no_formal_ino = cpu_to_be64(0);
+	dent->de_hash = cpu_to_be32(name->hash);
+	dent->de_rec_len = cpu_to_be16(reclen);
+	dent->de_name_len = cpu_to_be16(name->len);
+	dent->de_type = cpu_to_be16(0);
+	memset(dent->__pad, 0, sizeof(dent->__pad));
+	memcpy((char*)(dent+1), name->name, name->len);
+}
 
 #endif /* __DIR_DOT_H__ */