ext4: Use new buffer_head flag to check uninit group bitmaps initialization

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 4235817..0cedf3b 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -319,18 +319,41 @@  ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 			    block_group, bitmap_blk);
 		return NULL;
 	}
-	if (bh_uptodate_or_lock(bh))
+
+	if (bitmap_uptodate(bh))
 		return bh;
 
+  	lock_buffer(bh);
+ 	if (bitmap_uptodate(bh)) {
+ 		unlock_buffer(bh);
+ 		return bh;
+ 	}
 	spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
 	if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 		ext4_init_block_bitmap(sb, bh, block_group, desc);
+		set_bitmap_uptodate(bh);
 		set_buffer_uptodate(bh);
 		unlock_buffer(bh);
 		spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
 		return bh;
 	}
 	spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+	if (buffer_uptodate(bh)) {
+ 		/*
+ 		 * if not uninit if bh is uptodate,
+ 		 * bitmap is also uptodate
+ 		 */
+ 		set_bitmap_uptodate(bh);
+ 		unlock_buffer(bh);
+ 		return bh;
+ 	}
+ 	/*
+ 	 * submit the buffer_head for read. We can
+ 	 * safely mark the bitmap as uptodate now.
+ 	 * We do it here so the bitmap uptodate bit
+ 	 * get set with buffer lock held.
+ 	 */
+ 	set_bitmap_uptodate(bh);
 	if (bh_submit_read(bh) < 0) {
 		put_bh(bh);
 		ext4_error(sb, __func__,
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index e605295..1bbab6a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -19,6 +19,7 @@ 
 #include <linux/types.h>
 #include <linux/blkdev.h>
 #include <linux/magic.h>
+#include <linux/jbd2.h>
 #include "ext4_i.h"
 
 /*
@@ -1250,6 +1251,23 @@  extern int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode,
 			sector_t block, unsigned long max_blocks,
 			struct buffer_head *bh, int create,
 			int extend_disksize, int flag);
+/*
+ * Add new method to test wether block and inode bitmaps are properly
+ * initialized. With uninit_bg reading the block from disk is not enough
+ * to mark the bitmap uptodate. We need to also zero-out the bitmap
+ */
+#define BH_BITMAP_UPTODATE BH_JBDPrivateStart
+ 
+static inline int bitmap_uptodate(struct buffer_head *bh)
+{
+	return (buffer_uptodate(bh) &&
+ 			test_bit(BH_BITMAP_UPTODATE, &(bh)->b_state));
+}
+static inline void set_bitmap_uptodate(struct buffer_head *bh)
+{
+	set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state);
+}
+ 
 #endif	/* __KERNEL__ */
 
 #endif	/* _EXT4_H */
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index c61168d..9b9705c 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -115,18 +115,40 @@  ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
 			    block_group, bitmap_blk);
 		return NULL;
 	}
-	if (bh_uptodate_or_lock(bh))
+	if (bitmap_uptodate(bh))
 		return bh;
 
+  	lock_buffer(bh);
+ 	if (bitmap_uptodate(bh)) {
+ 		unlock_buffer(bh);
+ 		return bh;
+ 	}
 	spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
 	if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
 		ext4_init_inode_bitmap(sb, bh, block_group, desc);
+		set_bitmap_uptodate(bh);
 		set_buffer_uptodate(bh);
 		unlock_buffer(bh);
 		spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
 		return bh;
 	}
 	spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+ 	if (buffer_uptodate(bh)) {
+ 		/*
+ 		 * if not uninit if bh is uptodate,
+ 		 * bitmap is also uptodate
+ 		 */
+ 		set_bitmap_uptodate(bh);
+ 		unlock_buffer(bh);
+ 		return bh;
+ 	}
+ 	/*
+ 	 * submit the buffer_head for read. We can
+ 	 * safely mark the bitmap as uptodate now.
+ 	 * We do it here so the bitmap uptodate bit
+ 	 * get set with buffer lock held.
+ 	 */
+ 	set_bitmap_uptodate(bh);
 	if (bh_submit_read(bh) < 0) {
 		put_bh(bh);
 		ext4_error(sb, __func__,
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index ea13c5e..417e254 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -796,20 +796,42 @@  static int ext4_mb_init_cache(struct page *page, char *incore)
 		if (bh[i] == NULL)
 			goto out;
 
-		if (bh_uptodate_or_lock(bh[i]))
+		if (bitmap_uptodate(bh[i]))
 			continue;
 
+  		lock_buffer(bh[i]);
+ 		if (bitmap_uptodate(bh[i])) {
+ 			unlock_buffer(bh[i]);
+ 			continue;
+		}
 		spin_lock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
 		if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 			ext4_init_block_bitmap(sb, bh[i],
 						first_group + i, desc);
+			set_bitmap_uptodate(bh[i]);
 			set_buffer_uptodate(bh[i]);
 			unlock_buffer(bh[i]);
 			spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
 			continue;
 		}
 		spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
+ 		if (buffer_uptodate(bh[i])) {
+ 			/*
+ 			 * if not uninit if bh is uptodate,
+ 			 * bitmap is also uptodate
+ 			 */
+ 			set_bitmap_uptodate(bh[i]);
+ 			unlock_buffer(bh[i]);
+ 			continue;
+ 		}
 		get_bh(bh[i]);
+ 		/*
+ 		 * submit the buffer_head for read. We can
+ 		 * safely mark the bitmap as uptodate now.
+ 		 * We do it here so the bitmap uptodate bit
+ 		 * get set with buffer lock held.
+ 		 */
+ 		set_bitmap_uptodate(bh[i]);
 		bh[i]->b_end_io = end_buffer_read_sync;
 		submit_bh(READ, bh[i]);
 		mb_debug("read bitmap for group %lu\n", first_group + i);