netdev - [PATCH v4 13/17] filelock: lift the ban on directory leases in generic

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Message-Id: <20251103-dir-deleg-ro-v4-13-961b67adee89@kernel.org>
Date: Mon, 03 Nov 2025 07:52:41 -0500
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 v4 13/17] 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: Jan Kara <jack@...e.cz>
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 f5b210a2dc34c70ac36e972436c62482bbe32ca6..dd290a87f58eb5d522f03fa99d612fbad84dacf3 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1935,14 +1935,19 @@ 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;
@@ -2071,6 +2076,9 @@ 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);

-- 
2.51.1