diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 0d7f06e..1b8024d 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -64,7 +64,7 @@
 }
 
 /* Initializes an uninitialized inode bitmap */
-static unsigned ext4_init_inode_bitmap(struct super_block *sb,
+static int ext4_init_inode_bitmap(struct super_block *sb,
 				       struct buffer_head *bh,
 				       ext4_group_t block_group,
 				       struct ext4_group_desc *gdp)
@@ -89,7 +89,7 @@
 					   count);
 		}
 		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
-		return 0;
+		return -EFSBADCRC;
 	}
 
 	memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
@@ -99,7 +99,7 @@
 				   EXT4_INODES_PER_GROUP(sb) / 8);
 	ext4_group_desc_csum_set(sb, block_group, gdp);
 
-	return EXT4_INODES_PER_GROUP(sb);
+	return 0;
 }
 
 void ext4_end_bitmap_read(struct buffer_head *bh, int uptodate)
@@ -112,6 +112,42 @@
 	put_bh(bh);
 }
 
+static int ext4_validate_inode_bitmap(struct super_block *sb,
+				      struct ext4_group_desc *desc,
+				      ext4_group_t block_group,
+				      struct buffer_head *bh)
+{
+	ext4_fsblk_t	blk;
+	struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+	if (buffer_verified(bh))
+		return 0;
+	if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp))
+		return -EFSCORRUPTED;
+
+	ext4_lock_group(sb, block_group);
+	blk = ext4_inode_bitmap(sb, desc);
+	if (!ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
+					   EXT4_INODES_PER_GROUP(sb) / 8)) {
+		ext4_unlock_group(sb, block_group);
+		ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
+			   "inode_bitmap = %llu", block_group, blk);
+		grp = ext4_get_group_info(sb, block_group);
+		if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
+			int count;
+			count = ext4_free_inodes_count(sb, desc);
+			percpu_counter_sub(&sbi->s_freeinodes_counter,
+					   count);
+		}
+		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
+		return -EFSBADCRC;
+	}
+	set_buffer_verified(bh);
+	ext4_unlock_group(sb, block_group);
+	return 0;
+}
+
 /*
  * Read the inode allocation bitmap for a given block_group, reading
  * into the specified slot in the superblock's bitmap cache.
@@ -124,12 +160,11 @@
 	struct ext4_group_desc *desc;
 	struct buffer_head *bh = NULL;
 	ext4_fsblk_t bitmap_blk;
-	struct ext4_group_info *grp;
-	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	int err;
 
 	desc = ext4_get_group_desc(sb, block_group, NULL);
 	if (!desc)
-		return NULL;
+		return ERR_PTR(-EFSCORRUPTED);
 
 	bitmap_blk = ext4_inode_bitmap(sb, desc);
 	bh = sb_getblk(sb, bitmap_blk);
@@ -137,7 +172,7 @@
 		ext4_error(sb, "Cannot read inode bitmap - "
 			    "block_group = %u, inode_bitmap = %llu",
 			    block_group, bitmap_blk);
-		return NULL;
+		return ERR_PTR(-EIO);
 	}
 	if (bitmap_uptodate(bh))
 		goto verify;
@@ -150,12 +185,14 @@
 
 	ext4_lock_group(sb, block_group);
 	if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
-		ext4_init_inode_bitmap(sb, bh, block_group, desc);
+		err = ext4_init_inode_bitmap(sb, bh, block_group, desc);
 		set_bitmap_uptodate(bh);
 		set_buffer_uptodate(bh);
 		set_buffer_verified(bh);
 		ext4_unlock_group(sb, block_group);
 		unlock_buffer(bh);
+		if (err)
+			goto out;
 		return bh;
 	}
 	ext4_unlock_group(sb, block_group);
@@ -182,31 +219,17 @@
 		ext4_error(sb, "Cannot read inode bitmap - "
 			   "block_group = %u, inode_bitmap = %llu",
 			   block_group, bitmap_blk);
-		return NULL;
+		return ERR_PTR(-EIO);
 	}
 
 verify:
-	ext4_lock_group(sb, block_group);
-	if (!buffer_verified(bh) &&
-	    !ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
-					   EXT4_INODES_PER_GROUP(sb) / 8)) {
-		ext4_unlock_group(sb, block_group);
-		put_bh(bh);
-		ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
-			   "inode_bitmap = %llu", block_group, bitmap_blk);
-		grp = ext4_get_group_info(sb, block_group);
-		if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
-			int count;
-			count = ext4_free_inodes_count(sb, desc);
-			percpu_counter_sub(&sbi->s_freeinodes_counter,
-					   count);
-		}
-		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
-		return NULL;
-	}
-	ext4_unlock_group(sb, block_group);
-	set_buffer_verified(bh);
+	err = ext4_validate_inode_bitmap(sb, desc, block_group, bh);
+	if (err)
+		goto out;
 	return bh;
+out:
+	put_bh(bh);
+	return ERR_PTR(err);
 }
 
 /*
@@ -286,8 +309,15 @@
 	bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
 	/* Don't bother if the inode bitmap is corrupt. */
 	grp = ext4_get_group_info(sb, block_group);
-	if (unlikely(EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) || !bitmap_bh)
+	if (IS_ERR(bitmap_bh)) {
+		fatal = PTR_ERR(bitmap_bh);
+		bitmap_bh = NULL;
 		goto error_return;
+	}
+	if (unlikely(EXT4_MB_GRP_IBITMAP_CORRUPT(grp))) {
+		fatal = -EFSCORRUPTED;
+		goto error_return;
+	}
 
 	BUFFER_TRACE(bitmap_bh, "get_write_access");
 	fatal = ext4_journal_get_write_access(handle, bitmap_bh);
@@ -826,7 +856,9 @@
 		brelse(inode_bitmap_bh);
 		inode_bitmap_bh = ext4_read_inode_bitmap(sb, group);
 		/* Skip groups with suspicious inode tables */
-		if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp) || !inode_bitmap_bh) {
+		if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp) ||
+		    IS_ERR(inode_bitmap_bh)) {
+			inode_bitmap_bh = NULL;
 			if (++group == ngroups)
 				group = 0;
 			continue;
@@ -902,8 +934,8 @@
 		struct buffer_head *block_bitmap_bh;
 
 		block_bitmap_bh = ext4_read_block_bitmap(sb, group);
-		if (!block_bitmap_bh) {
-			err = -EIO;
+		if (IS_ERR(block_bitmap_bh)) {
+			err = PTR_ERR(block_bitmap_bh);
 			goto out;
 		}
 		BUFFER_TRACE(block_bitmap_bh, "get block bitmap access");
@@ -1123,8 +1155,10 @@
 	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
 	bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
 	bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
-	if (!bitmap_bh) {
-		ext4_warning(sb, "inode bitmap error for orphan %lu", ino);
+	if (IS_ERR(bitmap_bh)) {
+		err = PTR_ERR(bitmap_bh);
+		ext4_warning(sb, "inode bitmap error %ld for orphan %lu",
+			     ino, err);
 		goto error;
 	}
 
@@ -1199,8 +1233,10 @@
 		desc_count += ext4_free_inodes_count(sb, gdp);
 		brelse(bitmap_bh);
 		bitmap_bh = ext4_read_inode_bitmap(sb, i);
-		if (!bitmap_bh)
+		if (IS_ERR(bitmap_bh)) {
+			bitmap_bh = NULL;
 			continue;
+		}
 
 		x = ext4_count_free(bitmap_bh->b_data,
 				    EXT4_INODES_PER_GROUP(sb) / 8);