linux-kernel - [PATCH 33/35] cifs: Add a new open flag CREATE_OPTION_EXCLUSIVE to open with deny all shared reservation

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Message-Id: <20250831123602.14037-34-pali@kernel.org>
Date: Sun, 31 Aug 2025 14:36:00 +0200
From: Pali Rohár <pali@...nel.org>
To: Steve French <sfrench@...ba.org>,
	Paulo Alcantara <pc@...guebit.com>,
	ronnie sahlberg <ronniesahlberg@...il.com>
Cc: linux-cifs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 33/35] cifs: Add a new open flag CREATE_OPTION_EXCLUSIVE to open with deny all shared reservation

This is just an internal flag for cifs.ko code, not exported to userspace.
It allows cifs.ko code to take an exclusive open with deny all shared
reservation. It is going to be used by the upcoming fixes for the unlink()
and rmdir() silly rename support.

Signed-off-by: Pali Rohár <pali@...nel.org>
---
 fs/smb/client/cifspdu.h |  1 +
 fs/smb/client/cifssmb.c | 12 ++++++++++--
 fs/smb/client/smb2pdu.c |  6 +++++-
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/cifspdu.h b/fs/smb/client/cifspdu.h
index cb1f99d22dd7..90b0b82e23b1 100644
--- a/fs/smb/client/cifspdu.h
+++ b/fs/smb/client/cifspdu.h
@@ -395,6 +395,7 @@
 #define CREATE_OPTIONS_MASK     0x007FFFFF
 #define CREATE_OPTION_READONLY	0x10000000
 #define CREATE_OPTION_SPECIAL   0x20000000   /* system. NB not sent over wire */
+#define CREATE_OPTION_EXCLUSIVE 0x40000000   /* exclusive open, NB not set over wire */
 
 /* ImpersonationLevel flags */
 #define SECURITY_ANONYMOUS      0
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index 3a0452479a69..37bc0541bc21 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -1125,7 +1125,11 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
 		pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
 
 	pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
-	pSMB->Mode |= cpu_to_le16(SMBOPEN_DENY_NONE);
+
+	if (create_options & CREATE_OPTION_EXCLUSIVE)
+		pSMB->Mode |= cpu_to_le16(SMBOPEN_DENY_ALL);
+	else
+		pSMB->Mode |= cpu_to_le16(SMBOPEN_DENY_NONE);
 
 	if (create_options & CREATE_WRITE_THROUGH)
 		pSMB->Mode |= cpu_to_le16(SMBOPEN_WRITE_THROUGH);
@@ -1281,7 +1285,11 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
 	if (create_options & CREATE_OPTION_READONLY)
 		req->FileAttributes |= cpu_to_le32(ATTR_READONLY);
 
-	req->ShareAccess = cpu_to_le32(FILE_SHARE_ALL);
+	if (create_options & CREATE_OPTION_EXCLUSIVE)
+		req->ShareAccess = cpu_to_le32(FILE_NO_SHARE);
+	else
+		req->ShareAccess = cpu_to_le32(FILE_SHARE_ALL);
+
 	req->CreateDisposition = cpu_to_le32(disposition);
 	req->CreateOptions = cpu_to_le32(create_options & CREATE_OPTIONS_MASK);
 
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index a6c69b01ec6b..8315213d699e 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -3034,7 +3034,11 @@ SMB2_open_init(struct cifs_tcon *tcon, struct TCP_Server_Info *server,
 	req->DesiredAccess = cpu_to_le32(oparms->desired_access);
 	/* File attributes ignored on open (used in create though) */
 	req->FileAttributes = cpu_to_le32(file_attributes);
-	req->ShareAccess = FILE_SHARE_ALL_LE;
+
+	if (oparms->create_options & CREATE_OPTION_EXCLUSIVE)
+		req->ShareAccess = cpu_to_le32(FILE_NO_SHARE);
+	else
+		req->ShareAccess = cpu_to_le32(FILE_SHARE_ALL);
 
 	req->CreateDisposition = cpu_to_le32(oparms->disposition);
 	req->CreateOptions = cpu_to_le32(oparms->create_options & CREATE_OPTIONS_MASK);
-- 
2.20.1