linux-kernel - [PATCH v2 8/9] kill lock_two

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Message-Id: <20231205022418.1703007-16-viro@zeniv.linux.org.uk>
Date:   Tue,  5 Dec 2023 02:24:07 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     linux-arch@...r.kernel.org
Cc:     gus Gusenleitner Klaus <gus@...a.com>,
        Al Viro <viro@....linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        "dsahern@...nel.org" <dsahern@...nel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 8/9] kill lock_two_inodes()

There's only one caller left (lock_two_nondirectories()), and it
needs less complexity.  Fold lock_two_inodes() in there and
simplify.

Reviewed-by: Jan Kara <jack@...e.cz>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/inode.c    | 49 ++++++-------------------------------------------
 fs/internal.h |  2 --
 2 files changed, 6 insertions(+), 45 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index edcd8a61975f..453d5be1a014 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1087,48 +1087,6 @@ void discard_new_inode(struct inode *inode)
 }
 EXPORT_SYMBOL(discard_new_inode);
 
-/**
- * lock_two_inodes - lock two inodes (may be regular files but also dirs)
- *
- * Lock any non-NULL argument. The caller must make sure that if he is passing
- * in two directories, one is not ancestor of the other.  Zero, one or two
- * objects may be locked by this function.
- *
- * @inode1: first inode to lock
- * @inode2: second inode to lock
- * @subclass1: inode lock subclass for the first lock obtained
- * @subclass2: inode lock subclass for the second lock obtained
- */
-void lock_two_inodes(struct inode *inode1, struct inode *inode2,
-		     unsigned subclass1, unsigned subclass2)
-{
-	if (!inode1 || !inode2) {
-		/*
-		 * Make sure @subclass1 will be used for the acquired lock.
-		 * This is not strictly necessary (no current caller cares) but
-		 * let's keep things consistent.
-		 */
-		if (!inode1)
-			swap(inode1, inode2);
-		goto lock;
-	}
-
-	/*
-	 * If one object is directory and the other is not, we must make sure
-	 * to lock directory first as the other object may be its child.
-	 */
-	if (S_ISDIR(inode2->i_mode) == S_ISDIR(inode1->i_mode)) {
-		if (inode1 > inode2)
-			swap(inode1, inode2);
-	} else if (!S_ISDIR(inode1->i_mode))
-		swap(inode1, inode2);
-lock:
-	if (inode1)
-		inode_lock_nested(inode1, subclass1);
-	if (inode2 && inode2 != inode1)
-		inode_lock_nested(inode2, subclass2);
-}
-
 /**
  * lock_two_nondirectories - take two i_mutexes on non-directory objects
  *
@@ -1144,7 +1102,12 @@ void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
 		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
 	if (inode2)
 		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
-	lock_two_inodes(inode1, inode2, I_MUTEX_NORMAL, I_MUTEX_NONDIR2);
+	if (inode1 > inode2)
+		swap(inode1, inode2);
+	if (inode1)
+		inode_lock(inode1);
+	if (inode2 && inode2 != inode1)
+		inode_lock_nested(inode2, I_MUTEX_NONDIR2);
 }
 EXPORT_SYMBOL(lock_two_nondirectories);
 
diff --git a/fs/internal.h b/fs/internal.h
index 58e43341aebf..de67b02226e5 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -196,8 +196,6 @@ extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc);
 int dentry_needs_remove_privs(struct mnt_idmap *, struct dentry *dentry);
 bool in_group_or_capable(struct mnt_idmap *idmap,
 			 const struct inode *inode, vfsgid_t vfsgid);
-void lock_two_inodes(struct inode *inode1, struct inode *inode2,
-		     unsigned subclass1, unsigned subclass2);
 
 /*
  * fs-writeback.c
-- 
2.39.2