From: Randy Dunlap <randy.dunlap@oracle.com>

Use NULL instead of 0 for pointers:
fs/ext4/writeback.c:874:24: warning: Using plain integer as NULL pointer
fs/ext4/writeback.c:1105:23: warning: Using plain integer as NULL pointer

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/ext4/writeback.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff -puN fs/ext4/writeback.c~ext4-use-null-for-pointers fs/ext4/writeback.c
--- a/fs/ext4/writeback.c~ext4-use-null-for-pointers
+++ a/fs/ext4/writeback.c
@@ -41,6 +41,7 @@
 #include <linux/jbd.h>
 #include <linux/ext4_fs_extents.h>
 #include <linux/smp_lock.h>
+#include <linux/stddef.h>
 #include <linux/highuid.h>
 #include <linux/pagemap.h>
 #include <linux/quotaops.h>
@@ -871,7 +872,7 @@ int ext4_wb_prepare_write(struct file *f
 				wb_debug("read block %u\n",
 						(unsigned) bhw->b_blocknr);
 				set_bh_page(bhw, page, 0);
-				bhw->b_this_page = 0;
+				bhw->b_this_page = NULL;
 				bhw->b_size = 1 << inode->i_blkbits;
 				atomic_set(&bhw->b_count, 1);
 				ll_rw_block(READ, 1, &bhw);
@@ -1102,7 +1103,7 @@ int ext4_wb_block_truncate_page(handle_t
 			wb_debug("read block %u for part.trunc on %lu\n",
 					(unsigned) bhw->b_blocknr, page->index);
 			set_bh_page(bhw, page, 0);
-			bhw->b_this_page = 0;
+			bhw->b_this_page = NULL;
 			bhw->b_size = 1 << inode->i_blkbits;
 			atomic_set(&bhw->b_count, 1);
 			ll_rw_block(READ, 1, &bhw);
_