fs/buffer.c: remove unnecessary init operation after allocating buffer_head.

bh allocation uses kmem_cache_zalloc() so we needn't call
'init_buffer(bh, NULL, NULL)' and perform other set-zero-operations.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/buffer.c

@@ -865,8 +865,6 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 
 		/* Link the buffer to its page */
 		set_bh_page(bh, page, offset);
-
-		init_buffer(bh, NULL, NULL);
 	}
 	return head;
 /*

fs/jbd/journal.c

@@ -310,8 +310,6 @@ int journal_write_metadata_buffer(transaction_t *transaction,
 
 	new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
 	/* keep subsequent assertions sane */
-	new_bh->b_state = 0;
-	init_buffer(new_bh, NULL, NULL);
 	atomic_set(&new_bh->b_count, 1);
 	new_jh = journal_add_journal_head(new_bh);	/* This sleeps */
 

fs/jbd2/journal.c

@@ -367,8 +367,6 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	}
 
 	/* keep subsequent assertions sane */
-	new_bh->b_state = 0;
-	init_buffer(new_bh, NULL, NULL);
 	atomic_set(&new_bh->b_count, 1);
 	new_jh = jbd2_journal_add_journal_head(new_bh);	/* This sleeps */