From patchwork Thu Nov 7 21:00:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 13867098 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 7BABD227B91; Thu, 7 Nov 2024 21:00:18 +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=1731013218; cv=none; b=hC9J+U45eICBJ2qdjb59SXeVl7bfPw3bQGEmTTd0qgmp8tvfbZ7vBErgV4ZAKnFx2O+dYMVrQjtkNRWKiUFxcHb95fUSKIrJRMh1rusdgRltF9gaXC9+R6ObL1rRdIEZ5ZAj367/ypuCqHgVs5ctS12TTwS/HMjWapOIfY8icWg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731013218; c=relaxed/simple; bh=Xk5GmckVGwbKY64HejHicOU/dRi3TybyQoiny9Ds7dI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=MdoUvyDkpUPkOG6ZBDoq85pUvaXZ/7I/693FfgWmZUtqmjvTe80hzJfsSKI6wr2iqNJWmd0ms+VZC4NhLXM5tu9mR5BA+JxMIzr55iA2u1THg3MTkpSZGGBjQE2RcQtZ1k1ki7Qkutk/cTI11KxnjZQuvytYxdOKNvUy+lYuVWE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JYq6UO4K; 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="JYq6UO4K" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5885DC4CECE; Thu, 7 Nov 2024 21:00:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731013218; bh=Xk5GmckVGwbKY64HejHicOU/dRi3TybyQoiny9Ds7dI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=JYq6UO4Kr/cTMEFxLhhFbFJaDY7tFVWylaFki9TIg8xvdy6Q1sKuAOfyX5iwyAyuv OmfF94E41Bkc9ZgfdAipq60QEre4QjIGFMvcYzAXt1WuTusekgJxlfIv1qfEjGqfAY Fr0ChgckyYRP5o0XetclevdRdG7Nm3o+AKiClAcqJxHZCKs1s1lKJ2WTq+B+1gHcQc FkPxddv8FefI3i0PK/CpJ+EnD1qoppWqbhz08nkOv1ZwP5NTWob5cJcn3SJ5ZQ3Ogf 3vvLvwUeLE4soPsl+dvMQHLve5y1Y2KdOogQrhJYUiOtB/ToG1ao8NGoR/qtgH2u2O pPCF0wOoEBANA== From: Jeff Layton Date: Thu, 07 Nov 2024 16:00:06 -0500 Subject: [PATCH v3 1/2] fs: add the ability for statmount() to report the fs_subtype Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241107-statmount-v3-1-da5b9744c121@kernel.org> References: <20241107-statmount-v3-0-da5b9744c121@kernel.org> In-Reply-To: <20241107-statmount-v3-0-da5b9744c121@kernel.org> To: Alexander Viro , Christian Brauner , Jan Kara Cc: Miklos Szeredi , Ian Kent , Josef Bacik , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Layton X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4590; i=jlayton@kernel.org; h=from:subject:message-id; bh=Xk5GmckVGwbKY64HejHicOU/dRi3TybyQoiny9Ds7dI=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBnLSpfYG+d1kMK04rIn89VYAQARS0GrwjMCH5MM x2TIxls4GyJAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZy0qXwAKCRAADmhBGVaC FbEgD/922p3HIAQxKFePCk3K3NL5wC+/2S7ZJn55RQ1aApbsot4hgIG01JpJtwBW1TweSB2jCAr pdm0Dx/JcsbQsVx0S14Iz8bIHyCm1fq/NqpSQYuZ1lkeFvxWR7xEQ8u6QxwRjzUmCvwC9ZNYi8C P7m8S6+1YyehQyoI/g+F8f+CgdQT1lhPZ9Z29B3IssWlo8rzvKwzMF6Cu4wxGcAFIKw0dmE+KB7 HMpKr2KBBkp3tqYWUNFHpBF2fNhs7IajppbYwjpTqNMw8lqYsi2MrTZHm97S7uq8KLfOx4StqIB Rz5RUJCZquiihnbKtqsygw41sKRLFe9a0mpMgS5YEaIbqxFlTEunSf/5ECU+B5zLR6NLMmGMBF6 Lnp2Hqwhi29FeQrcuOwc9KFvm7GhkNIX1wsAlGGXg6lz4YO3bDlDHhYyOGyrX6I+aA1FDmek/Mz BZOFIhvIOWw/Uc6N1giLRTFkVuAgI/jOGmnNgHEtGQeyi4CPAUhpwiq/a9M3hYyppMfvb7h6E2H ahWyO9ioRDEBQl7HMuXmmZIaA87xZTsEZUHFO2fvauprhlWm9ClB6z8IHcYr5OLI279rnekd4Jp NtzbrQZEtzsrnKZAp2HzjWpCfvuwRZ8dTgWQKrV5EDnxL1ubhulJCPNGFssAuKqNp6IZyGOtVWq tnpiSA4okLLBYbA== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 /proc/self/mountinfo prints out the sb->s_subtype after the type. This is particularly useful for disambiguating FUSE mounts (at least when the userland driver bothers to set it). Add STATMOUNT_FS_SUBTYPE and claim one of the __spare2 fields to point to the offset into the str[] array. Handle the case where there is no subtype by not setting STATMOUNT_FS_SUBTYPE in the returned mask. Check whether the function emitted anything and just return immediately if not. Reviewed-by: Jan Kara Reviewed-by: Ian Kent Signed-off-by: Jeff Layton --- fs/namespace.c | 34 ++++++++++++++++++++++++++++------ include/uapi/linux/mount.h | 5 ++++- 2 files changed, 32 insertions(+), 7 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index ba77ce1c6788dfe461814b5826fcbb3aab68fad4..fc4f81891d544305caf863904c0a6e16562fab49 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5006,6 +5006,14 @@ static int statmount_fs_type(struct kstatmount *s, struct seq_file *seq) return 0; } +static void statmount_fs_subtype(struct kstatmount *s, struct seq_file *seq) +{ + struct super_block *sb = s->mnt->mnt_sb; + + if (sb->s_subtype) + seq_puts(seq, sb->s_subtype); +} + static void statmount_mnt_ns_id(struct kstatmount *s, struct mnt_namespace *ns) { s->sm.mask |= STATMOUNT_MNT_NS_ID; @@ -5042,33 +5050,44 @@ static int statmount_mnt_opts(struct kstatmount *s, struct seq_file *seq) static int statmount_string(struct kstatmount *s, u64 flag) { - int ret; + int ret = 0; size_t kbufsize; struct seq_file *seq = &s->seq; struct statmount *sm = &s->sm; + u32 start = seq->count; switch (flag) { case STATMOUNT_FS_TYPE: - sm->fs_type = seq->count; + sm->fs_type = start; ret = statmount_fs_type(s, seq); break; case STATMOUNT_MNT_ROOT: - sm->mnt_root = seq->count; + sm->mnt_root = start; ret = statmount_mnt_root(s, seq); break; case STATMOUNT_MNT_POINT: - sm->mnt_point = seq->count; + sm->mnt_point = start; ret = statmount_mnt_point(s, seq); break; case STATMOUNT_MNT_OPTS: - sm->mnt_opts = seq->count; + sm->mnt_opts = start; ret = statmount_mnt_opts(s, seq); break; + case STATMOUNT_FS_SUBTYPE: + sm->fs_subtype = start; + statmount_fs_subtype(s, seq); + break; default: WARN_ON_ONCE(true); return -EINVAL; } + /* + * If nothing was emitted, return to avoid setting the flag + * and terminating the buffer. + */ + if (seq->count == start) + return ret; if (unlikely(check_add_overflow(sizeof(*sm), seq->count, &kbufsize))) return -EOVERFLOW; if (kbufsize >= s->bufsize) @@ -5203,6 +5222,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_MNT_OPTS) err = statmount_string(s, STATMOUNT_MNT_OPTS); + if (!err && s->mask & STATMOUNT_FS_SUBTYPE) + err = statmount_string(s, STATMOUNT_FS_SUBTYPE); + if (!err && s->mask & STATMOUNT_MNT_NS_ID) statmount_mnt_ns_id(s, ns); @@ -5224,7 +5246,7 @@ static inline bool retry_statmount(const long ret, size_t *seq_size) } #define STATMOUNT_STRING_REQ (STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT | \ - STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS) + STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | STATMOUNT_FS_SUBTYPE) static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq, struct statmount __user *buf, size_t bufsize, diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 225bc366ffcbf0319929e2f55f1fbea88e4d7b81..2e939dddf9cbabe574dafdb6cff9ad4cf9298a74 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -173,7 +173,9 @@ struct statmount { __u32 mnt_root; /* [str] Root of mount relative to root of fs */ __u32 mnt_point; /* [str] Mountpoint relative to current root */ __u64 mnt_ns_id; /* ID of the mount namespace */ - __u64 __spare2[49]; + __u32 fs_subtype; /* [str] Subtype of fs_type (if any) */ + __u32 __spare1[1]; + __u64 __spare2[48]; char str[]; /* Variable size part containing strings */ }; @@ -207,6 +209,7 @@ struct mnt_id_req { #define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */ #define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ #define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ +#define STATMOUNT_FS_SUBTYPE 0x00000100U /* Want/got fs_subtype */ /* * Special @mnt_id values that can be passed to listmount From patchwork Thu Nov 7 21:00:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 13867099 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 92E9F227BBB; Thu, 7 Nov 2024 21:00:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 /proc/self/mountinfo displays the devicename for the mount, but statmount() doesn't yet have a way to return it. Add a new STATMOUNT_MNT_DEVNAME flag, claim the 32-bit __spare1 field to hold the offset into the str[] array. STATMOUNT_MNT_DEVNAME will only be set in the return mask if there is a device string. Signed-off-by: Jeff Layton Reviewed-by: Jan Kara --- fs/namespace.c | 36 +++++++++++++++++++++++++++++++++++- include/uapi/linux/mount.h | 3 ++- 2 files changed, 37 insertions(+), 2 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index fc4f81891d544305caf863904c0a6e16562fab49..56750fcc890271e22b3b722dc0b4af445686bb86 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5014,6 +5014,32 @@ static void statmount_fs_subtype(struct kstatmount *s, struct seq_file *seq) seq_puts(seq, sb->s_subtype); } +static int statmount_mnt_devname(struct kstatmount *s, struct seq_file *seq) +{ + struct super_block *sb = s->mnt->mnt_sb; + struct mount *r = real_mount(s->mnt); + + if (sb->s_op->show_devname) { + size_t start = seq->count; + int ret; + + ret = sb->s_op->show_devname(seq, s->mnt->mnt_root); + if (ret) + return ret; + + if (unlikely(seq_has_overflowed(seq))) + return -EAGAIN; + + /* Unescape the result */ + seq->buf[seq->count] = '\0'; + seq->count = start; + seq_commit(seq, string_unescape_inplace(seq->buf + start, UNESCAPE_OCTAL)); + } else if (r->mnt_devname) { + seq_puts(seq, r->mnt_devname); + } + return 0; +} + static void statmount_mnt_ns_id(struct kstatmount *s, struct mnt_namespace *ns) { s->sm.mask |= STATMOUNT_MNT_NS_ID; @@ -5077,6 +5103,10 @@ static int statmount_string(struct kstatmount *s, u64 flag) sm->fs_subtype = start; statmount_fs_subtype(s, seq); break; + case STATMOUNT_MNT_DEVNAME: + sm->mnt_devname = seq->count; + ret = statmount_mnt_devname(s, seq); + break; default: WARN_ON_ONCE(true); return -EINVAL; @@ -5225,6 +5255,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_FS_SUBTYPE) err = statmount_string(s, STATMOUNT_FS_SUBTYPE); + if (!err && s->mask & STATMOUNT_MNT_DEVNAME) + err = statmount_string(s, STATMOUNT_MNT_DEVNAME); + if (!err && s->mask & STATMOUNT_MNT_NS_ID) statmount_mnt_ns_id(s, ns); @@ -5246,7 +5279,8 @@ static inline bool retry_statmount(const long ret, size_t *seq_size) } #define STATMOUNT_STRING_REQ (STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT | \ - STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | STATMOUNT_FS_SUBTYPE) + STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | \ + STATMOUNT_FS_SUBTYPE | STATMOUNT_MNT_DEVNAME) static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq, struct statmount __user *buf, size_t bufsize, diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 2e939dddf9cbabe574dafdb6cff9ad4cf9298a74..3de1b0231b639fb8ed739d65b5b5406021f74196 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -174,7 +174,7 @@ struct statmount { __u32 mnt_point; /* [str] Mountpoint relative to current root */ __u64 mnt_ns_id; /* ID of the mount namespace */ __u32 fs_subtype; /* [str] Subtype of fs_type (if any) */ - __u32 __spare1[1]; + __u32 mnt_devname; /* [str] Device string for the mount */ __u64 __spare2[48]; char str[]; /* Variable size part containing strings */ }; @@ -210,6 +210,7 @@ struct mnt_id_req { #define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ #define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ #define STATMOUNT_FS_SUBTYPE 0x00000100U /* Want/got fs_subtype */ +#define STATMOUNT_MNT_DEVNAME 0x00000200U /* Want/got mnt_devname */ /* * Special @mnt_id values that can be passed to listmount