[PATCH 5/7] follow_dotdot{,_rcu}(): don't bother with inode

From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrey Konovalov <andreyknvl@google.com>,
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Borislav Petkov <bp@alien8.de>, Christoph Hellwig <hch@lst.de>,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Ilya Leoshkevich <iii@linux.ibm.com>,
	Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Kees Cook <keescook@chromium.org>, Marco Elver <elver@google.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Matthew Wilcox <willy@infradead.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Pekka Enberg <penberg@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Petr Mladek <pmladek@suse.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vasily Gorbik <gor@linux.ibm.com>,
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	Evgenii Stepanov <eugenis@google.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Segher Boessenkool <segher@kernel.crashing.org>,
	Vitaly Buka <vitalybuka@google.com>,
	linux-toolchains <linux-toolchains@vger.kernel.org>
Subject: [PATCH 5/7] follow_dotdot{,_rcu}(): don't bother with inode
Date: Tue, 5 Jul 2022 00:15:38 +0100	[thread overview]
Message-ID: <YsN0mtY5ecwW7MS3@ZenIV> (raw)
In-Reply-To: <YsN0GURKuaAqXB/e@ZenIV>

step_into() will fetch it, TYVM.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/namei.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index dddbebf92b48..fe95fe39634c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1880,8 +1880,7 @@ static const char *step_into(struct nameidata *nd, int flags,
 	return pick_link(nd, &path, inode, flags);
 }
 
-static struct dentry *follow_dotdot_rcu(struct nameidata *nd,
-					struct inode **inodep)
+static struct dentry *follow_dotdot_rcu(struct nameidata *nd)
 {
 	struct dentry *parent, *old;
 
@@ -1905,7 +1904,6 @@ static struct dentry *follow_dotdot_rcu(struct nameidata *nd,
 	}
 	old = nd->path.dentry;
 	parent = old->d_parent;
-	*inodep = parent->d_inode;
 	nd->next_seq = read_seqcount_begin(&parent->d_seq);
 	// makes sure that non-RCU pathwalk could reach this state
 	if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
@@ -1919,12 +1917,10 @@ static struct dentry *follow_dotdot_rcu(struct nameidata *nd,
 	if (unlikely(nd->flags & LOOKUP_BENEATH))
 		return ERR_PTR(-ECHILD);
 	nd->next_seq = nd->seq;
-	*inodep = nd->path.dentry->d_inode;
 	return nd->path.dentry;
 }
 
-static struct dentry *follow_dotdot(struct nameidata *nd,
-				 struct inode **inodep)
+static struct dentry *follow_dotdot(struct nameidata *nd)
 {
 	struct dentry *parent;
 
@@ -1948,13 +1944,11 @@ static struct dentry *follow_dotdot(struct nameidata *nd,
 		dput(parent);
 		return ERR_PTR(-ENOENT);
 	}
-	*inodep = parent->d_inode;
 	return parent;
 
 in_root:
 	if (unlikely(nd->flags & LOOKUP_BENEATH))
 		return ERR_PTR(-EXDEV);
-	*inodep = nd->path.dentry->d_inode;
 	return dget(nd->path.dentry);
 }
 
@@ -1963,7 +1957,6 @@ static const char *handle_dots(struct nameidata *nd, int type)
 	if (type == LAST_DOTDOT) {
 		const char *error = NULL;
 		struct dentry *parent;
-		struct inode *inode;
 
 		if (!nd->root.mnt) {
 			error = ERR_PTR(set_root(nd));
@@ -1971,9 +1964,9 @@ static const char *handle_dots(struct nameidata *nd, int type)
 				return error;
 		}
 		if (nd->flags & LOOKUP_RCU)
-			parent = follow_dotdot_rcu(nd, &inode);
+			parent = follow_dotdot_rcu(nd);
 		else
-			parent = follow_dotdot(nd, &inode);
+			parent = follow_dotdot(nd);
 		if (IS_ERR(parent))
 			return ERR_CAST(parent);
 		error = step_into(nd, WALK_NOFOLLOW, parent);
-- 
2.30.2


