Btrfs: Fix mount -o max_inline=0

max_inline=0 used to force the max_inline size to one sector instead.  Now
it properly disables inline data items, while still being able to read
any that happen to exist on disk.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/super.c

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 346932e5..f3274be 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -184,8 +184,11 @@
 				info->max_inline = btrfs_parse_size(num);
 				kfree(num);
 
-				info->max_inline = max_t(u64,
-					info->max_inline, root->sectorsize);
+				if (info->max_inline) {
+					info->max_inline = max_t(u64,
+						info->max_inline,
+						root->sectorsize);
+				}
 				printk(KERN_INFO "btrfs: max_inline at %llu\n",
 					info->max_inline);
 			}