[PATCH 04/13] Apparmor: Use simple_start_creating() / simple_done_creating()

[NeilBrown]

From: NeilBrown <neil at brown.name>

Instead of explicitly locking the parent and performing a look up in
apparmor, use simple_start_creating(), and then simple_done_creating()
to unlock and drop the dentry.

This removes the need to check for an existing entry (as
simple_start_creating() acts like an exclusive create and can return
-EEXIST), simplifies error paths, and keeps dir locking code
centralised.

Signed-off-by: NeilBrown <neil at brown.name>
---
 security/apparmor/apparmorfs.c | 38 ++++++++--------------------------
 1 file changed, 9 insertions(+), 29 deletions(-)

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 907bd2667e28..7f78c36e6e50 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -282,32 +282,19 @@ static struct dentry *aafs_create(const char *name, umode_t mode,
 
 	dir = d_inode(parent);
 
-	inode_lock(dir);
-	dentry = lookup_noperm(&QSTR(name), parent);
+	dentry = simple_start_creating(parent, name);
 	if (IS_ERR(dentry)) {
 		error = PTR_ERR(dentry);
-		goto fail_lock;
-	}
-
-	if (d_really_is_positive(dentry)) {
-		error = -EEXIST;
-		goto fail_dentry;
+		goto fail;
 	}
 
 	error = __aafs_setup_d_inode(dir, dentry, mode, data, link, fops, iops);
+	simple_done_creating(dentry);
 	if (error)
-		goto fail_dentry;
-	inode_unlock(dir);
-
-	return dentry;
-
-fail_dentry:
-	dput(dentry);
-
-fail_lock:
-	inode_unlock(dir);
+		goto fail;
+	return 0;
+fail:
 	simple_release_fs(&aafs_mnt, &aafs_count);
-
 	return ERR_PTR(error);
 }
 
@@ -2572,8 +2559,7 @@ static int aa_mk_null_file(struct dentry *parent)
 	if (error)
 		return error;
 
-	inode_lock(d_inode(parent));
-	dentry = lookup_noperm(&QSTR(NULL_FILE_NAME), parent);
+	dentry = simple_start_creating(parent, NULL_FILE_NAME);
 	if (IS_ERR(dentry)) {
 		error = PTR_ERR(dentry);
 		goto out;
@@ -2581,7 +2567,7 @@ static int aa_mk_null_file(struct dentry *parent)
 	inode = new_inode(parent->d_inode->i_sb);
 	if (!inode) {
 		error = -ENOMEM;
-		goto out1;
+		goto out;
 	}
 
 	inode->i_ino = get_next_ino();
@@ -2593,18 +2579,12 @@ static int aa_mk_null_file(struct dentry *parent)
 	aa_null.dentry = dget(dentry);
 	aa_null.mnt = mntget(mount);
 
-	error = 0;
-
-out1:
-	dput(dentry);
 out:
-	inode_unlock(d_inode(parent));
+	simple_done_creating(dentry);
 	simple_release_fs(&mount, &count);
 	return error;
 }
 
-
-
 static const char *policy_get_link(struct dentry *dentry,
 				   struct inode *inode,
 				   struct delayed_call *done)
-- 
2.50.0.107.gf914562f5916.dirty