linux-kernel - [PATCH 1/2] fs: touch up predicts in inode

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Message-ID: <20250416221626.2710239-2-mjguzik@gmail.com>
Date: Thu, 17 Apr 2025 00:16:25 +0200
From: Mateusz Guzik <mjguzik@...il.com>
To: brauner@...nel.org
Cc: torvalds@...ux-foundation.org,
	viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH 1/2] fs: touch up predicts in inode_permission()

The routine only encounters errors when people try to access things they
can't, which is a negligible amount of calls.

The only questionable bit might be the pre-existing predict around
MAY_WRITE. Currently the routine is predominantly used for MAY_EXEC, so
this makes some sense.

I verified this straightens out the asm.

Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---
 fs/namei.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index daebc307c1a3..cff69c12d6fd 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -571,14 +571,14 @@ int inode_permission(struct mnt_idmap *idmap,
 	int retval;
 
 	retval = sb_permission(inode->i_sb, inode, mask);
-	if (retval)
+	if (unlikely(retval))
 		return retval;
 
 	if (unlikely(mask & MAY_WRITE)) {
 		/*
 		 * Nobody gets write access to an immutable file.
 		 */
-		if (IS_IMMUTABLE(inode))
+		if (unlikely(IS_IMMUTABLE(inode)))
 			return -EPERM;
 
 		/*
@@ -586,16 +586,16 @@ int inode_permission(struct mnt_idmap *idmap,
 		 * written back improperly if their true value is unknown
 		 * to the vfs.
 		 */
-		if (HAS_UNMAPPED_ID(idmap, inode))
+		if (unlikely(HAS_UNMAPPED_ID(idmap, inode)))
 			return -EACCES;
 	}
 
 	retval = do_inode_permission(idmap, inode, mask);
-	if (retval)
+	if (unlikely(retval))
 		return retval;
 
 	retval = devcgroup_inode_permission(inode, mask);
-	if (retval)
+	if (unlikely(retval))
 		return retval;
 
 	return security_inode_permission(inode, mask);
-- 
2.48.1