fs: take the ACL checks to common code

Replace the ->check_acl method with a ->get_acl method that simply reads an
ACL from disk after having a cache miss.  This means we can replace the ACL
checking boilerplate code with a single implementation in namei.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ext4/namei.c

@@ -2590,7 +2590,7 @@ const struct inode_operations ext4_dir_inode_operations = {
 	.listxattr	= ext4_listxattr,
 	.removexattr	= generic_removexattr,
 #endif
-	.check_acl	= ext4_check_acl,
+	.get_acl	= ext4_get_acl,
 	.fiemap         = ext4_fiemap,
 };
 
@@ -2602,5 +2602,5 @@ const struct inode_operations ext4_special_inode_operations = {
 	.listxattr	= ext4_listxattr,
 	.removexattr	= generic_removexattr,
 #endif
-	.check_acl	= ext4_check_acl,
+	.get_acl	= ext4_get_acl,
 };