linux-kernel - [PATCH v2 2/6] kernfs: move revalidate to be near lookup

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Date:   Wed, 17 Jun 2020 15:37:53 +0800
From:   Ian Kent <raven@...maw.net>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Tejun Heo <tj@...nel.org>, Stephen Rothwell <sfr@...b.auug.org.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...IV.linux.org.uk>,
        Rick Lindsley <ricklind@...ux.vnet.ibm.com>,
        David Howells <dhowells@...hat.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 2/6] kernfs: move revalidate to be near lookup

While the dentry operation kernfs_dop_revalidate() is grouped with
dentry'ish functions it also has a strong afinity to the inode
operation ->lookup(). And when path walk improvements are applied
it will need to call kernfs_find_ns() so move it to be near
kernfs_iop_lookup() to avoid the need for a forward declaration.

There's no functional change from this patch.

Signed-off-by: Ian Kent <raven@...maw.net>
---
 fs/kernfs/dir.c |   86 ++++++++++++++++++++++++++++---------------------------
 1 file changed, 43 insertions(+), 43 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index d8213fc65eba..9b315f3b20ee 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -559,49 +559,6 @@ void kernfs_put(struct kernfs_node *kn)
 }
 EXPORT_SYMBOL_GPL(kernfs_put);
 
-static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
-{
-	struct kernfs_node *kn;
-
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	/* Always perform fresh lookup for negatives */
-	if (d_really_is_negative(dentry))
-		goto out_bad_unlocked;
-
-	kn = kernfs_dentry_node(dentry);
-	down_read(&kernfs_rwsem);
-
-	/* The kernfs node has been deactivated */
-	if (!kernfs_active_read(kn))
-		goto out_bad;
-
-	/* The kernfs node has been moved? */
-	if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
-		goto out_bad;
-
-	/* The kernfs node has been renamed */
-	if (strcmp(dentry->d_name.name, kn->name) != 0)
-		goto out_bad;
-
-	/* The kernfs node has been moved to a different namespace */
-	if (kn->parent && kernfs_ns_enabled(kn->parent) &&
-	    kernfs_info(dentry->d_sb)->ns != kn->ns)
-		goto out_bad;
-
-	up_read(&kernfs_rwsem);
-	return 1;
-out_bad:
-	up_read(&kernfs_rwsem);
-out_bad_unlocked:
-	return 0;
-}
-
-const struct dentry_operations kernfs_dops = {
-	.d_revalidate	= kernfs_dop_revalidate,
-};
-
 /**
  * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
  * @dentry: the dentry in question
@@ -1085,6 +1042,49 @@ struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
 	return ERR_PTR(rc);
 }
 
+static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct kernfs_node *kn;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	/* Always perform fresh lookup for negatives */
+	if (d_really_is_negative(dentry))
+		goto out_bad_unlocked;
+
+	kn = kernfs_dentry_node(dentry);
+	down_read(&kernfs_rwsem);
+
+	/* The kernfs node has been deactivated */
+	if (!kernfs_active_read(kn))
+		goto out_bad;
+
+	/* The kernfs node has been moved? */
+	if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
+		goto out_bad;
+
+	/* The kernfs node has been renamed */
+	if (strcmp(dentry->d_name.name, kn->name) != 0)
+		goto out_bad;
+
+	/* The kernfs node has been moved to a different namespace */
+	if (kn->parent && kernfs_ns_enabled(kn->parent) &&
+	    kernfs_info(dentry->d_sb)->ns != kn->ns)
+		goto out_bad;
+
+	up_read(&kernfs_rwsem);
+	return 1;
+out_bad:
+	up_read(&kernfs_rwsem);
+out_bad_unlocked:
+	return 0;
+}
+
+const struct dentry_operations kernfs_dops = {
+	.d_revalidate	= kernfs_dop_revalidate,
+};
+
 static struct dentry *kernfs_iop_lookup(struct inode *dir,
 					struct dentry *dentry,
 					unsigned int flags)