From nobody Mon Feb 9 15:06:49 2026 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 BF03E84FA0; Tue, 2 Apr 2024 13:11:04 +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=1712063464; cv=none; b=X84UypSy5Rf8PdNtsHs3pXY3OvPUC08Up3tljtGgUXxHAgLf2zJCmLaGCl8K014DOupLnq/YqsGe25fxQ8kW4HsPvcYuUjAoeyOoiTkGcrUpCvEaNRsj/rWOo7QOab1ndWVjfhBJwkXzS8s9g2WCXbkZNVPM3tqJkAnjfteaIak= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712063464; c=relaxed/simple; bh=z5ftgWu8Ra0zpOJ1b9c3WKlj8qgG1oMSVZZQwaE7zsU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=rkE2Tm7fTTalJBGasUU9B/AVVDVXBT7dMIp1gnAAjYLR2gT6T1E88DvpB+nEhiPiRWIYqZPdArG9SoIG2GdINMaW/VNwpGKLPgb6CLDM6XqiqyFKGKSn8nHoRgoNDaF5mf+S0fsEuHpMc6src1hFusX+/kjjqmJlVSY22i2XCCo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ra5rTJra; 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="ra5rTJra" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4DBAC433C7; Tue, 2 Apr 2024 13:11:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712063464; bh=z5ftgWu8Ra0zpOJ1b9c3WKlj8qgG1oMSVZZQwaE7zsU=; h=From:Date:Subject:To:Cc:From; b=ra5rTJraG+89L9ZWvJvdB3sz4/wSDPqC2yO9IyYSCCLiVVqrLyZ7bztknKfHGM4wB Pihv6dT2oXClDocCbTNwkUWw/pgKH1Pjc/BUe8YICVBboQEiEYIoD20chIMvRNFyL5 n63+A3hvrxI2GTTHzjlsSGKiDRKbGTK95ERrccH4oeRWfYd+LYQOTCOR+HD8e54ihI baUKCwAfjIxbdd2FuI/Ue9VGyWgk8kSJTZPoSscz1gFXUQqtDat9Sfvup1Ymug3OBO TuIOM8ioidwlanbp7eQl+KWQU7eIiDAfn/FheZmRixfZxW971raFR+bNrral/q3SGt L8buvO5K02nvw== From: Jeff Layton Date: Tue, 02 Apr 2024 09:10:59 -0400 Subject: [PATCH v2] fuse: allow FUSE drivers to declare themselves free from outside changes 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: <20240402-setlease-v2-1-b098a5f9295d@kernel.org> X-B4-Tracking: v=1; b=H4sIAOIDDGYC/23MQQ6DIBSE4auYty4NoAbbVe/RuEAcldSAAUPaG O5e6rrLfzL5DooIFpHu1UEByUbrXQl5qcgs2s1gdixNksuG1+LGIvYVOoIZ1GIaOqXUwKnct4D Jvk/q2ZdebNx9+JxyEr/1D5IEE6wxaLWUHF07Pl4IDuvVh5n6nPMXJU0/BaEAAAA= To: Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Layton X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4466; i=jlayton@kernel.org; h=from:subject:message-id; bh=z5ftgWu8Ra0zpOJ1b9c3WKlj8qgG1oMSVZZQwaE7zsU=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBmDAPnXJvae21imEUXw9IWkX/IlcYgW2n9bbmh8 oVoswE2n62JAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZgwD5wAKCRAADmhBGVaC FQUEEACgR+cPI6gQDVV2g2uLq3sQMUiJZ9WN1lXUi71fPAfcYQuVNdzX2DzvA9QimmAMhD7TL3n oEM9oXNh6DerUHXiXjVAHswIs8nOAMb52t4mBglzBmKaGnxGkiBx0DPJg9GIFNWWdCIkYWQzQ1a RG0MVGo0tKCybBe6VR0f6JycPBC4Cd2vyiRvWISICWVyBiDYwvh3rnViyvb2n4cCufejLMyvdl0 azVzW3PUWKrYra9oITvj8WYvVos73tOqpInUcn6ukPLeGb82/cyikKGP8lxEG4PoO72jtV0HWK+ 3eB3C96vudLDKnSV9MoOorhYxGdOlVm9DtLPTNae/BpeV9SCsB39dtXGg4+ns02s1SPNOQV3Fi0 7O0RYoAvI9BrhFvszwyo3rQGNWKqjB0LDfbKD/DXFk4k6ppp+n0Lr8EebZyNyYNnAYuy35SDC9c C66I/JbMrQoFwZRJ6/xBiXGARtW6Nc5FudpdJZdYRwMOO+8877VH+pwEDjKDt1v3BtoDR8atyTE lsgV75VsaY/mALD2mdvM7QedCXtHs9xNb9PltM4ZHnd8RILcXpC08H3HfIQZU4yojJgnz/N2Znx 9eGt6iWoMv28ghNhwKx6NV6dG8LWdj4rNVmjGJvbQrYvzBEW2vaW/NtmBl47MpqJRpQLyPjb4qc qihsHoB6aXduPUw== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 Traditionally, we've allowed people to set leases on FUSE inodes. Some FUSE drivers are effectively local filesystems and should be fine with kernel-internal lease support. Others are backed by a network server that may have multiple clients, or may be backed by something non-file like entirely. On those, we don't want to allow leases. Have the filesytem driver to set a fuse_conn flag to indicate whether the inodes are subject to outside changes, not done via kernel APIs. If the flag is unset (the default), then setlease attempts will fail with -EINVAL, indicating that leases aren't supported on that inode. Local-ish filesystems may want to start setting this value to true to preserve the ability to set leases. Signed-off-by: Jeff Layton --- This is only tested for compilation, but it's fairly straightforward. I've left the default the "safe" value of false, so that we assume that outside changes are possible unless told otherwise. --- Changes in v2: - renamed flag to FUSE_NO_OUTSIDE_CHANGES - flesh out comment describing the new flag --- fs/fuse/file.c | 11 +++++++++++ fs/fuse/fuse_i.h | 5 +++++ fs/fuse/inode.c | 4 +++- include/uapi/linux/fuse.h | 1 + 4 files changed, 20 insertions(+), 1 deletion(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index a56e7bffd000..79c7152c0d12 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -3298,6 +3298,16 @@ static ssize_t fuse_copy_file_range(struct file *src= _file, loff_t src_off, return ret; } =20 +static int fuse_setlease(struct file *file, int arg, + struct file_lease **flp, void **priv) +{ + struct fuse_conn *fc =3D get_fuse_conn(file_inode(file)); + + if (fc->no_outside_changes) + return generic_setlease(file, arg, flp, priv); + return -EINVAL; +} + static const struct file_operations fuse_file_operations =3D { .llseek =3D fuse_file_llseek, .read_iter =3D fuse_file_read_iter, @@ -3317,6 +3327,7 @@ static const struct file_operations fuse_file_operati= ons =3D { .poll =3D fuse_file_poll, .fallocate =3D fuse_file_fallocate, .copy_file_range =3D fuse_copy_file_range, + .setlease =3D fuse_setlease, }; =20 static const struct address_space_operations fuse_file_aops =3D { diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index b24084b60864..49d44a07b0db 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -860,6 +860,11 @@ struct fuse_conn { /** Passthrough support for read/write IO */ unsigned int passthrough:1; =20 + /** Can we assume that the only changes will be done via the local + * kernel? If the driver represents a network filesystem or is a front + * for data that can change on its own, set this to false. */ + unsigned int no_outside_changes:1; + /** Maximum stack depth for passthrough backing files */ int max_stack_depth; =20 diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 3a5d88878335..f33aedccdb26 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1330,6 +1330,8 @@ static void process_init_reply(struct fuse_mount *fm,= struct fuse_args *args, } if (flags & FUSE_NO_EXPORT_SUPPORT) fm->sb->s_export_op =3D &fuse_export_fid_operations; + if (flags & FUSE_NO_OUTSIDE_CHANGES) + fc->no_outside_changes =3D 1; } else { ra_pages =3D fc->max_read / PAGE_SIZE; fc->no_lock =3D 1; @@ -1377,7 +1379,7 @@ void fuse_send_init(struct fuse_mount *fm) FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_INIT_EXT | FUSE_SECURITY_CTX | FUSE_CREATE_SUPP_GROUP | FUSE_HAS_EXPIRE_ONLY | FUSE_DIRECT_IO_ALLOW_MMAP | - FUSE_NO_EXPORT_SUPPORT | FUSE_HAS_RESEND; + FUSE_NO_EXPORT_SUPPORT | FUSE_HAS_RESEND | FUSE_NO_OUTSIDE_CHANGES; #ifdef CONFIG_FUSE_DAX if (fm->fc->dax) flags |=3D FUSE_MAP_ALIGNMENT; diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index d08b99d60f6f..703d149d45ff 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -463,6 +463,7 @@ struct fuse_file_lock { #define FUSE_PASSTHROUGH (1ULL << 37) #define FUSE_NO_EXPORT_SUPPORT (1ULL << 38) #define FUSE_HAS_RESEND (1ULL << 39) +#define FUSE_NO_OUTSIDE_CHANGES (1ULL << 40) =20 /* Obsolete alias for FUSE_DIRECT_IO_ALLOW_MMAP */ #define FUSE_DIRECT_IO_RELAX FUSE_DIRECT_IO_ALLOW_MMAP --- base-commit: 026e680b0a08a62b1d948e5a8ca78700bfac0e6e change-id: 20240319-setlease-ce31fb8777b0 Best regards, --=20 Jeff Layton