[PATCH -V2] ext4: Drop mapped buffer_head check during page_mkwrite

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Inorder to check whether the buffer_heads are mapped we need
to hold page lock. Otherwise a reclaim can cleanup the attached
buffer_heads. Instead of taking page lock and check whether
buffer_heads are mapped we let the write_begin/write_end callback
does the equivalent. It does have a performance impact in that we
are doing more work if we the buffer_heads are already mapped.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/inode.c |   11 -----------
 1 files changed, 0 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f9c642b..ad99286 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5245,11 +5245,6 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 	return err;
 }
 
-static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
-{
-	return !buffer_mapped(bh);
-}