ext4: Properly initialize the buffer_head state

These struct buffer_heads are allocated on the stack (and hence are
initialized with stack garbage).  They are only used to call a
get_blocks() function, so that's mostly OK, but b_state must be
initialized to be 0 so we don't have any unexpected BH_* flags set by
accident, such as BH_Unwritten or BH_Delay.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/mpage.c b/fs/mpage.c
index 680ba60863ff..42381bd6543b 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -379,7 +379,8 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
         struct buffer_head map_bh;
         unsigned long first_logical_block = 0;
 
-        clear_buffer_mapped(&map_bh);
+        map_bh.b_state = 0;
+        map_bh.b_size = 0;
         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
                 struct page *page = list_entry(pages->prev, struct page, lru);
 
@@ -412,7 +413,8 @@ int mpage_readpage(struct page *page, get_block_t get_block)
         struct buffer_head map_bh;
         unsigned long first_logical_block = 0;
 
-        clear_buffer_mapped(&map_bh);
+        map_bh.b_state = 0;
+        map_bh.b_size = 0;
         bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
                         &map_bh, &first_logical_block, get_block);
         if (bio)