linux-kernel - [PATCH 2/6] r/o bind mount prepwork: move open_namei()'s vfs

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Message-Id: <20060809165731.20FD1397@localhost.localdomain>
Date:	Wed, 09 Aug 2006 09:57:31 -0700
From:	Dave Hansen <haveblue@...ibm.com>
To:	akpm@...l.org
Cc:	linux-kernel@...r.kernel.org, hch@...radead.org,
	Dave Hansen <haveblue@...ibm.com>
Subject: [PATCH 2/6] r/o bind mount prepwork: move open_namei()'s vfs_create()


The code around vfs_create() in open_namei() is getting a
bit too complex.  Right now, there is at least the reference
count on the dentry, and the i_mutex to worry about.  Soon,
we'll also have mnt_writecount.

So, break the vfs_create() call out of open_namei(), and
into a helper function.  This duplicates the call to
may_open(), but that isn't such a bad thing since the
arguments (acc_mode and flag) were being heavily massaged
anyway.

Signed-off-by: Dave Hansen <haveblue@...ibm.com>
---

 lxc-dave/fs/namei.c |   30 ++++++++++++++++++++----------
 1 files changed, 20 insertions(+), 10 deletions(-)

diff -puN fs/namei.c~B2-prepwork-cleanup-open_namei fs/namei.c
--- lxc/fs/namei.c~B2-prepwork-cleanup-open_namei	2006-08-08 09:18:49.000000000 -0700
+++ lxc-dave/fs/namei.c	2006-08-08 09:18:50.000000000 -0700
@@ -1587,6 +1587,24 @@ int may_open(struct nameidata *nd, int a
 	return 0;
 }
 
+static int open_namei_create(struct nameidata *nd, struct path *path,
+				int flag, int mode)
+{
+	int error;
+	struct dentry *dir = nd->dentry;
+
+	if (!IS_POSIXACL(dir->d_inode))
+		mode &= ~current->fs->umask;
+	error = vfs_create(dir->d_inode, path->dentry, mode, nd);
+	mutex_unlock(&dir->d_inode->i_mutex);
+	dput(nd->dentry);
+	nd->dentry = path->dentry;
+	if (error)
+		return error;
+	/* Don't check for write permission, don't truncate */
+	return may_open(nd, 0, flag & ~O_TRUNC);
+}
+
 /*
  *	open_namei()
  *
@@ -1668,18 +1686,10 @@ do_last:
 
 	/* Negative dentry, just create the file */
 	if (!path.dentry->d_inode) {
-		if (!IS_POSIXACL(dir->d_inode))
-			mode &= ~current->fs->umask;
-		error = vfs_create(dir->d_inode, path.dentry, mode, nd);
-		mutex_unlock(&dir->d_inode->i_mutex);
-		dput(nd->dentry);
-		nd->dentry = path.dentry;
+		error = open_namei_create(nd, &path, flag, mode);
 		if (error)
 			goto exit;
-		/* Don't check for write permission, don't truncate */
-		acc_mode = 0;
-		flag &= ~O_TRUNC;
-		goto ok;
+		return 0;
 	}
 
 	/*
_
-
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