f2fs: simplfy a field name in struct f2fs_extent,extent_info

Rename a filed name from 'blk_addr' to 'blk' in struct {f2fs_extent,extent_info}
as annotation of this field descripts its meaning well to us.

By this way, we can avoid long statement in code of following patches.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c3caa3c..5d2e52e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -278,7 +278,7 @@
 
 struct extent_info {
 	unsigned int fofs;	/* start offset in a file */
-	u32 blk_addr;		/* start block address of the extent */
+	u32 blk;		/* start block address of the extent */
 	unsigned int len;	/* length of the extent */
 };
 
@@ -320,7 +320,7 @@
 					struct f2fs_extent i_ext)
 {
 	ext->fofs = le32_to_cpu(i_ext.fofs);
-	ext->blk_addr = le32_to_cpu(i_ext.blk_addr);
+	ext->blk = le32_to_cpu(i_ext.blk);
 	ext->len = le32_to_cpu(i_ext.len);
 }
 
@@ -328,7 +328,7 @@
 					struct f2fs_extent *i_ext)
 {
 	i_ext->fofs = cpu_to_le32(ext->fofs);
-	i_ext->blk_addr = cpu_to_le32(ext->blk_addr);
+	i_ext->blk = cpu_to_le32(ext->blk);
 	i_ext->len = cpu_to_le32(ext->len);
 }