linux-kernel - [PATCH v3 09/13] filelock: lift the ban on directory leases in generic

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Message-Id: <20251021-dir-deleg-ro-v3-9-a08b1cde9f4c@kernel.org>
Date: Tue, 21 Oct 2025 11:25:44 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Miklos Szeredi <miklos@...redi.hu>, 
 Alexander Viro <viro@...iv.linux.org.uk>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
 Chuck Lever <chuck.lever@...cle.com>, 
 Alexander Aring <alex.aring@...il.com>, 
 Trond Myklebust <trondmy@...nel.org>, Anna Schumaker <anna@...nel.org>, 
 Steve French <sfrench@...ba.org>, Paulo Alcantara <pc@...guebit.org>, 
 Ronnie Sahlberg <ronniesahlberg@...il.com>, 
 Shyam Prasad N <sprasad@...rosoft.com>, Tom Talpey <tom@...pey.com>, 
 Bharath SM <bharathsm@...rosoft.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>, 
 David Howells <dhowells@...hat.com>, Tyler Hicks <code@...icks.com>, 
 NeilBrown <neil@...wn.name>, Olga Kornievskaia <okorniev@...hat.com>, 
 Dai Ngo <Dai.Ngo@...cle.com>, Amir Goldstein <amir73il@...il.com>, 
 Namjae Jeon <linkinjeon@...nel.org>, Steve French <smfrench@...il.com>, 
 Sergey Senozhatsky <senozhatsky@...omium.org>, 
 Carlos Maiolino <cem@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-nfs@...r.kernel.org, linux-cifs@...r.kernel.org, 
 samba-technical@...ts.samba.org, netfs@...ts.linux.dev, 
 ecryptfs@...r.kernel.org, linux-unionfs@...r.kernel.org, 
 linux-xfs@...r.kernel.org, netdev@...r.kernel.org, 
 Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v3 09/13] filelock: lift the ban on directory leases in
 generic_setlease

With the addition of the try_break_lease calls in directory changing
operations, allow generic_setlease to hand them out. Write leases on
directories are never allowed however, so continue to reject them.

For now, there is no API for requesting delegations from userland, so
ensure that userland is prevented from acquiring a lease on a directory.

Reviewed-by: NeilBrown <neil@...wn.name>
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/locks.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 0b16921fb52e602ea2e0c3de39d9d772af98ba7d..b47552106769ec5a189babfe12518e34aa59c759 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1929,14 +1929,19 @@ static int generic_delete_lease(struct file *filp, void *owner)
 int generic_setlease(struct file *filp, int arg, struct file_lease **flp,
 			void **priv)
 {
-	if (!S_ISREG(file_inode(filp)->i_mode))
+	struct inode *inode = file_inode(filp);
+
+	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
 		return -EINVAL;

 	switch (arg) {
 	case F_UNLCK:
 		return generic_delete_lease(filp, *priv);
-	case F_RDLCK:
 	case F_WRLCK:
+		if (S_ISDIR(inode->i_mode))
+			return -EINVAL;
+		fallthrough;
+	case F_RDLCK:
 		if (!(*flp)->fl_lmops->lm_break) {
 			WARN_ON_ONCE(1);
 			return -ENOLCK;
@@ -2065,6 +2070,9 @@ static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg)
  */
 int fcntl_setlease(unsigned int fd, struct file *filp, int arg)
 {
+	if (S_ISDIR(file_inode(filp)->i_mode))
+		return -EINVAL;
+
 	if (arg == F_UNLCK)
 		return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
 	return do_fcntl_add_lease(fd, filp, arg);

-- 
2.51.0