[PATCH 3/4] BTRFS: Set NOSEC early for btrfs

[Andi Kleen <andi@firstfloor.org>]

From: Andi Kleen <ak@linux.intel.com>

Based on a suggestion from Josef Bacik.

The btrfs inode lookup already does a quick check for xattrs.
If it doesn't find any and the file is not sgid set the NOSEC flag.
This avoids a xattr lookup on the first write.

Cc: josef@redhat.com
Cc: chris.mason@oracle.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 fs/btrfs/inode.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 7cd8ab0..b309c30 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2544,8 +2544,11 @@ static void btrfs_read_locked_inode(struct inode *inode)
 	 * any xattrs or acls
 	 */
 	maybe_acls = acls_after_inode_item(leaf, path->slots[0], inode->i_ino);
-	if (!maybe_acls)
+	if (!maybe_acls) {
 		cache_no_acl(inode);
+		if (!is_sgid(inode->i_mode))
+			inode->i_flags |= S_NOSEC;
+	}
 
 	BTRFS_I(inode)->block_group = btrfs_find_block_group(root, 0,
 						alloc_group_block, 0);
@@ -4616,6 +4619,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 		    (BTRFS_I(dir)->flags & BTRFS_INODE_NODATACOW))
 			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
 	}
+	if (!is_sgid(mode))
+		inode->i_flags |= S_NOSEC;
 
 	insert_inode_hash(inode);
 	inode_tree_add(inode);
-- 
1.7.4.4