linux-kernel - [PATCH v2] cifs: remove unnecessary copies of tcon->crfid.fid

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Message-ID: <20210415152409.GA2286719@LEGION>
Date:   Thu, 15 Apr 2021 20:24:09 +0500
From:   Muhammad Usama Anjum <musamaanjum@...il.com>
To:     aaptel@...e.com, Steve French <sfrench@...ba.org>,
        Ronnie Sahlberg <lsahlber@...hat.com>,
        "open list:COMMON INTERNET FILE SYSTEM CLIENT (CIFS)" 
        <linux-cifs@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Cc:     musamaanjum@...il.com, kernel-janitors@...r.kernel.org,
        dan.carpenter@...cle.com, colin.king@...onical.com
Subject: [PATCH v2] cifs: remove unnecessary copies of tcon->crfid.fid

pfid is being set to tcon->crfid.fid and they are copied in each other
multiple times. Remove the memcopy between same pointers - memory
locations.

Addresses-Coverity: ("Overlapped copy")
Fixes: 9e81e8ff74b9 ("cifs: return cached_fid from open_shroot")
Signed-off-by: Muhammad Usama Anjum <musamaanjum@...il.com>
---
Changes in V2:
	refcount increment is necessary. Don't remove it.
	Add and improve comments.

fs/cifs/smb2ops.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index caa5432a5ed1..797a20714ca1 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -848,11 +848,9 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 		};
 
 		/*
-		 * caller expects this func to set pfid to a valid
-		 * cached root, so we copy the existing one and get a
-		 * reference.
+		 * caller expects this func to set the fid in crfid to valid
+		 * cached root, so increment the refcount.
 		 */
-		memcpy(pfid, tcon->crfid.fid, sizeof(*pfid));
 		kref_get(&tcon->crfid.refcount);
 
 		mutex_unlock(&tcon->crfid.fid_mutex);
@@ -885,7 +883,6 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid->mid = le64_to_cpu(o_rsp->sync_hdr.MessageId);
 #endif /* CIFS_DEBUG2 */
 
-	memcpy(tcon->crfid.fid, pfid, sizeof(struct cifs_fid));
 	tcon->crfid.tcon = tcon;
 	tcon->crfid.is_valid = true;
 	tcon->crfid.dentry = dentry;
@@ -894,6 +891,10 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 
 	/* BB TBD check to see if oplock level check can be removed below */
 	if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE) {
+		/*
+		 * caller expects this func to set the fid in crfid to valid
+		 * cached root, so increment the refcount.
+		 */
 		kref_get(&tcon->crfid.refcount);
 		tcon->crfid.has_lease = true;
 		smb2_parse_contexts(server, o_rsp,
-- 
2.25.1