| Message ID | 20241107-statmount-v3-2-da5b9744c121@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fs: allow statmount to fetch the subtype and devname | expand |
On Thu 07-11-24 16:00:07, Jeff Layton wrote: > /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 <jlayton@kernel.org> Looks good to me. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > 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 > > -- > 2.47.0 >
On Thu, 7 Nov 2024 at 22:00, Jeff Layton <jlayton@kernel.org> wrote: > 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 */ One more point: this is called source in both the old mount(2) API and in new the fsconfig(2) API, where it's handled just like a plain option (i.e. "-osource=/dev/foo"). Also this is a sb property, not a mount property, so the naming is confusing. So I'd call this "sb_source" for consistency. Thanks, Miklos
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
/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 <jlayton@kernel.org> --- fs/namespace.c | 36 +++++++++++++++++++++++++++++++++++- include/uapi/linux/mount.h | 3 ++- 2 files changed, 37 insertions(+), 2 deletions(-)