ocfs2: fix wrong check in ocfs2_direct_IO_get_blocks

contig_blocks gotten from ocfs2_extent_map_get_blocks cannot be compared
with clusters_to_alloc. So convert it to clusters first.
Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Reviewed-by: Weiwei Wang <wangww631@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/aops.c

@@ -523,7 +523,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
 	unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
 	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 	unsigned long len = bh_result->b_size;
-	unsigned int clusters_to_alloc = 0;
+	unsigned int clusters_to_alloc = 0, contig_clusters = 0;
 
 	cpos = ocfs2_blocks_to_clusters(inode->i_sb, iblock);
 
@@ -560,8 +560,10 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
 		/* fill hole, allocate blocks can't be larger than the size
 		 * of the hole */
 		clusters_to_alloc = ocfs2_clusters_for_bytes(inode->i_sb, len);
-		if (clusters_to_alloc > contig_blocks)
-			clusters_to_alloc = contig_blocks;
+		contig_clusters = ocfs2_clusters_for_blocks(inode->i_sb,
+				contig_blocks);
+		if (clusters_to_alloc > contig_clusters)
+			clusters_to_alloc = contig_clusters;
 
 		/* allocate extent and insert them into the extent tree */
 		ret = ocfs2_extend_allocation(inode, cpos,

fs/ocfs2/ocfs2.h

@@ -717,6 +717,16 @@ static inline u64 ocfs2_clusters_to_blocks(struct super_block *sb,
 	return (u64)clusters << c_to_b_bits;
 }
 
+static inline u32 ocfs2_clusters_for_blocks(struct super_block *sb,
+		u64 blocks)
+{
+	int b_to_c_bits = OCFS2_SB(sb)->s_clustersize_bits -
+			sb->s_blocksize_bits;
+
+	blocks += (1 << b_to_c_bits) - 1;
+	return (u32)(blocks >> b_to_c_bits);
+}
+
 static inline u32 ocfs2_blocks_to_clusters(struct super_block *sb,
 					   u64 blocks)
 {