From nobody Tue Dec 2 02:29:43 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A7BAE3612E9; Wed, 19 Nov 2025 13:42:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763559763; cv=none; b=KxsmOdzLJJ4j8N2biA1ifO5Vc2Ux1LCpcblcW2h2uaFqaSm0PKn5Wo9IOjBZMzRC6qy2WmVDq2wEzIF9kW//2VJAfWO6HIxB6nEgDAOh7Be1Y8FkR4X82xiyeTxCHhm1wEFLcPll/0QeNC9R/eoJsEoDUhf3N6Kggrje6CP68iI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763559763; c=relaxed/simple; bh=bOsgYjPeUMmPlZY4cRL+96QYFL7r0WVAw5+qEW5Suvo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Y/KpCMWrax3vuSD8GxiAGrsM6tY6TkoOsBXhS3M+6aFwUbrT+CQYS4f69QEkNwjswYYrpS5Mu9V4qbW+gRkT87jNGMPzgWBjH+jEFSkNR5aK+TTCjKGPPVORHlDSA4VMkjgW7mZc8UvItGmrpkxUyQRXfecOh4RGOl0RuZG5tmw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ktexG/gu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ktexG/gu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B00DCC2BCB6; Wed, 19 Nov 2025 13:42:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763559762; bh=bOsgYjPeUMmPlZY4cRL+96QYFL7r0WVAw5+qEW5Suvo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ktexG/gu+z6XOVhONgGEnD7abxAfddd09s5oKjiVzfcugnDli9klLcxc/2YdAxNUb UVgfsjSGiGQ8G/h1zqZLWUI1auozQwEpVBezxJBcCOPnFmCPI7wwy0dNWg7QnSQ6/J O2B+6Uw22hdUXsUG8tk3fN0LnkNKAqWsgl3ZdGkaQagO5dYn+VcIlOVgQuV8MZZf0T CMKNKLkmSaOIPHj4DwidUPUCprDZmrQhyYXR0Y78DC6ckN9NnGErHtV5lLBsX3fFFk J6hAychofZXBymPZIXkEqt5PhXPiKmMeSTHhPOW+mqcS/E/eM8fApyVpPCBXvjtAOy Ik+7LPTVfqNOw== From: Jeff Layton Date: Wed, 19 Nov 2025 08:42:18 -0500 Subject: [PATCH v8 1/3] vfs: expose delegation support to userland Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251119-dir-deleg-ro-v8-1-81b6cf5485c6@kernel.org> References: <20251119-dir-deleg-ro-v8-0-81b6cf5485c6@kernel.org> In-Reply-To: <20251119-dir-deleg-ro-v8-0-81b6cf5485c6@kernel.org> To: Alexander Viro , Christian Brauner , Jan Kara , Jeff Layton , Chuck Lever , Alexander Aring , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, Stephen Rothwell X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=8057; i=jlayton@kernel.org; h=from:subject:message-id; bh=bOsgYjPeUMmPlZY4cRL+96QYFL7r0WVAw5+qEW5Suvo=; b=owEBbQKS/ZANAwAKAQAOaEEZVoIVAcsmYgBpHclPCvJ5fmEIyYv3UXwu8nHA70rNSfvoCSU9S dVvU8TyOjyJAjMEAAEKAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCaR3JTwAKCRAADmhBGVaC Fb3xEADDya80yW/Om5bTNCsIwU6GnQKVhTTWAs/UBbdLSAhfpjFlKi1hoIjGlGiWh9ZT+u2qtXV PPkr4yZpxzlXpogyRuitbr8jjr7lb9qJQtydxcGkj23BEbQ6PXGEsi+sX3I4vnLnPUpGZD45LGt 0jqUDiG/yRb7HuToswrJtsVRQ04FgT+IdtpKzIe7OFlHOR1wub/xEcwhrPAhUrsSU3AGVre4Mpp 7W7XM0v6ZMDandGkUHrRxHaj9xiTogyA/03xvP0k3Ep2qu9Rjd8H0C3BwjXVnMUpXI/bRhcM72P WtSMhT98T7EOWZW63+w7zaH03PBVwiBDLfOc96GlgVkSUDCMVPYGmxLiHfVNt3Z/rmcRd9ez5WW opgq7pmlAKJ1vxH+CVytXDKIt+QTHtS9uZQJT1HhzY888EmzjTKxEnbTAM3m8En6kujOG73WJtq a3txsWVfi306svANoE13i17Y264/ZucAbp1SkD/0oxrrd2k/6Q6ut13zJzsMH7pcBE8rZGHJipA p37PdOak1YunT1MElZolsy8KqtYy5DfH/dXIc06BmVNwIsMmFoVIYLs6UjUpuUg9qMiTrc7Xbft KuAja0MkTqmLU3HOk5505Dy27KmHtlemChPxpfevisJXqYseHRng9umpIxrbddM/Vjmz2048K/B 5gUwWl8D5f1v8Sw== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 Now that support for recallable directory delegations is available, expose this functionality to userland with new F_SETDELEG and F_GETDELEG commands for fcntl(). Note that this also allows userland to request a FL_DELEG type lease on files too. Userland applications that do will get signalled when there are metadata changes in addition to just data changes (which is a limitation of FL_LEASE leases). These commands accept a new "struct delegation" argument that contains a flags field for future expansion. Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-17-52f3feebb2f2@ker= nel.org Reviewed-by: Jan Kara Signed-off-by: Christian Brauner --- fs/fcntl.c | 13 +++++++ fs/locks.c | 94 ++++++++++++++++++++++++++++++++++--------= ---- include/linux/filelock.h | 12 ++++++ include/uapi/linux/fcntl.h | 16 ++++++++ 4 files changed, 110 insertions(+), 25 deletions(-) diff --git a/fs/fcntl.c b/fs/fcntl.c index 72f8433d9109889eecef56b32d20a85b4e12ea44..f93dbca0843557d197bd1e02351= 9cfa0f00ad78f 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -445,6 +445,7 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned= long arg, struct file *filp) { void __user *argp =3D (void __user *)arg; + struct delegation deleg; int argi =3D (int)arg; struct flock flock; long err =3D -EINVAL; @@ -550,6 +551,18 @@ static long do_fcntl(int fd, unsigned int cmd, unsigne= d long arg, case F_SET_RW_HINT: err =3D fcntl_set_rw_hint(filp, arg); break; + case F_GETDELEG: + if (copy_from_user(&deleg, argp, sizeof(deleg))) + return -EFAULT; + err =3D fcntl_getdeleg(filp, &deleg); + if (!err && copy_to_user(argp, &deleg, sizeof(deleg))) + return -EFAULT; + break; + case F_SETDELEG: + if (copy_from_user(&deleg, argp, sizeof(deleg))) + return -EFAULT; + err =3D fcntl_setdeleg(fd, filp, &deleg); + break; default: break; } diff --git a/fs/locks.c b/fs/locks.c index dd290a87f58eb5d522f03fa99d612fbad84dacf3..3df07871b5ab7bbe883cdd8fba8= 22d130282da8e 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -1680,6 +1680,34 @@ void lease_get_mtime(struct inode *inode, struct tim= espec64 *time) } EXPORT_SYMBOL(lease_get_mtime); =20 +static int __fcntl_getlease(struct file *filp, unsigned int flavor) +{ + struct file_lease *fl; + struct inode *inode =3D file_inode(filp); + struct file_lock_context *ctx; + int type =3D F_UNLCK; + LIST_HEAD(dispose); + + ctx =3D locks_inode_context(inode); + if (ctx && !list_empty_careful(&ctx->flc_lease)) { + percpu_down_read(&file_rwsem); + spin_lock(&ctx->flc_lock); + time_out_leases(inode, &dispose); + list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) { + if (fl->c.flc_file !=3D filp) + continue; + if (fl->c.flc_flags & flavor) + type =3D target_leasetype(fl); + break; + } + spin_unlock(&ctx->flc_lock); + percpu_up_read(&file_rwsem); + + locks_dispose_list(&dispose); + } + return type; +} + /** * fcntl_getlease - Enquire what lease is currently active * @filp: the file @@ -1705,29 +1733,24 @@ EXPORT_SYMBOL(lease_get_mtime); */ int fcntl_getlease(struct file *filp) { - struct file_lease *fl; - struct inode *inode =3D file_inode(filp); - struct file_lock_context *ctx; - int type =3D F_UNLCK; - LIST_HEAD(dispose); - - ctx =3D locks_inode_context(inode); - if (ctx && !list_empty_careful(&ctx->flc_lease)) { - percpu_down_read(&file_rwsem); - spin_lock(&ctx->flc_lock); - time_out_leases(inode, &dispose); - list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) { - if (fl->c.flc_file !=3D filp) - continue; - type =3D target_leasetype(fl); - break; - } - spin_unlock(&ctx->flc_lock); - percpu_up_read(&file_rwsem); + return __fcntl_getlease(filp, FL_LEASE); +} =20 - locks_dispose_list(&dispose); - } - return type; +/** + * fcntl_getdeleg - enquire what sort of delegation is active + * @filp: file to be tested + * @deleg: structure where the result is stored + * + * Returns 0 on success or errno on failure. On success, + * deleg->d_type will contain the type of currently set lease + * (F_RDLCK, F_WRLCK or F_UNLCK). + */ +int fcntl_getdeleg(struct file *filp, struct delegation *deleg) +{ + if (deleg->d_flags !=3D 0 || deleg->__pad !=3D 0) + return -EINVAL; + deleg->d_type =3D __fcntl_getlease(filp, FL_DELEG); + return 0; } =20 /** @@ -2039,13 +2062,13 @@ vfs_setlease(struct file *filp, int arg, struct fil= e_lease **lease, void **priv) } EXPORT_SYMBOL_GPL(vfs_setlease); =20 -static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg) +static int do_fcntl_add_lease(unsigned int fd, struct file *filp, unsigned= int flavor, int arg) { struct file_lease *fl; struct fasync_struct *new; int error; =20 - fl =3D lease_alloc(filp, FL_LEASE, arg); + fl =3D lease_alloc(filp, flavor, arg); if (IS_ERR(fl)) return PTR_ERR(fl); =20 @@ -2081,7 +2104,28 @@ int fcntl_setlease(unsigned int fd, struct file *fil= p, int arg) =20 if (arg =3D=3D F_UNLCK) return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp); - return do_fcntl_add_lease(fd, filp, arg); + return do_fcntl_add_lease(fd, filp, FL_LEASE, arg); +} + +/** + * fcntl_setdeleg - sets a delegation on an open file + * @fd: open file descriptor + * @filp: file pointer + * @deleg: delegation request from userland + * + * Call this fcntl to establish a delegation on the file. + * Note that you also need to call %F_SETSIG to + * receive a signal when the lease is broken. + */ +int fcntl_setdeleg(unsigned int fd, struct file *filp, struct delegation *= deleg) +{ + /* For now, no flags are supported */ + if (deleg->d_flags !=3D 0 || deleg->__pad !=3D 0) + return -EINVAL; + + if (deleg->d_type =3D=3D F_UNLCK) + return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp); + return do_fcntl_add_lease(fd, filp, FL_DELEG, deleg->d_type); } =20 /** diff --git a/include/linux/filelock.h b/include/linux/filelock.h index 208d108df2d73a9df65e5dc9968d074af385f881..54b824c05299261e6bd6acc4175= cb277ea35b35d 100644 --- a/include/linux/filelock.h +++ b/include/linux/filelock.h @@ -159,6 +159,8 @@ int fcntl_setlk64(unsigned int, struct file *, unsigned= int, =20 int fcntl_setlease(unsigned int fd, struct file *filp, int arg); int fcntl_getlease(struct file *filp); +int fcntl_setdeleg(unsigned int fd, struct file *filp, struct delegation *= deleg); +int fcntl_getdeleg(struct file *filp, struct delegation *deleg); =20 static inline bool lock_is_unlock(struct file_lock *fl) { @@ -278,6 +280,16 @@ static inline int fcntl_getlease(struct file *filp) return F_UNLCK; } =20 +static inline int fcntl_setdeleg(unsigned int fd, struct file *filp, struc= t delegation *deleg) +{ + return -EINVAL; +} + +static inline int fcntl_getdeleg(struct file *filp, struct delegation *del= eg) +{ + return -EINVAL; +} + static inline bool lock_is_unlock(struct file_lock *fl) { return false; diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index 3741ea1b73d8500061567b6590ccf5fb4c6770f0..5e277fd955aae50fa59e93f23d4= 62415ac0ca171 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -4,6 +4,11 @@ =20 #include #include +#ifdef __KERNEL__ +#include +#else +#include +#endif =20 #define F_SETLEASE (F_LINUX_SPECIFIC_BASE + 0) #define F_GETLEASE (F_LINUX_SPECIFIC_BASE + 1) @@ -79,6 +84,17 @@ */ #define RWF_WRITE_LIFE_NOT_SET RWH_WRITE_LIFE_NOT_SET =20 +/* Set/Get delegations */ +#define F_GETDELEG (F_LINUX_SPECIFIC_BASE + 15) +#define F_SETDELEG (F_LINUX_SPECIFIC_BASE + 16) + +/* Argument structure for F_GETDELEG and F_SETDELEG */ +struct delegation { + uint32_t d_flags; /* Must be 0 */ + uint16_t d_type; /* F_RDLCK, F_WRLCK, F_UNLCK */ + uint16_t __pad; /* Must be 0 */ +}; + /* * Types of directory notifications that may be requested. */ --=20 2.51.1