linux-kernel - [PATCH 4/4] fs/unionfs/: Don't duplicate the struct nameidata

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Message-Id: <11701030643398-git-send-email-jsipek@cs.sunysb.edu>
Date:	Mon, 29 Jan 2007 15:37:42 -0500
From:	"Josef 'Jeff' Sipek" <jsipek@...sunysb.edu>
To:	linux-kernel@...r.kernel.org
Cc:	linux-fsdevel@...r.kernel.org, akpm@...l.org,
	"Josef 'Jeff' Sipek" <jsipek@...sunysb.edu>
Subject: [PATCH 4/4] fs/unionfs/: Don't duplicate the struct nameidata

The only fields that we have to watch out for are the dentry and vfsmount.
Additionally, this makes Unionfs gentler on the stack as nameidata is rather
large.

Signed-off-by: Josef 'Jeff' Sipek <jsipek@...sunysb.edu>
---
 fs/unionfs/inode.c |   22 ++++++++++++++++------
 1 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index 3b4a388..1b2e8a8 100644
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -191,15 +191,25 @@ static struct dentry *unionfs_lookup(struct inode *parent,
 				     struct dentry *dentry,
 				     struct nameidata *nd)
 {
-	struct nameidata lowernd; /* TODO: be gentler to the stack */
+	struct path path_save;
+	struct dentry *ret;
 
-	if (nd)
-		memcpy(&lowernd, nd, sizeof(struct nameidata));
-	else
-		memset(&lowernd, 0, sizeof(struct nameidata));
+	/* save the dentry & vfsmnt from namei */
+	if (nd) {
+		path_save.dentry = nd->dentry;
+		path_save.mnt = nd->mnt;
+	}
 
 	/* The locking is done by unionfs_lookup_backend. */
-	return unionfs_lookup_backend(dentry, &lowernd, INTERPOSE_LOOKUP);
+	ret = unionfs_lookup_backend(dentry, nd, INTERPOSE_LOOKUP);
+
+	/* restore the dentry & vfsmnt in namei */
+	if (nd) {
+		nd->dentry = path_save.dentry;
+		nd->mnt = path_save.mnt;
+	}
+
+	return ret;
 }
 
 static int unionfs_link(struct dentry *old_dentry, struct inode *dir,
-- 
1.5.0.rc1.g5355

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