| Message ID | 009928cf579a38577f8d6cc644c115556f9a3576.1720545710.git.josef@toxicpanda.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | man-pages: add documentation for statmount/listmount | expand |
Hi Josef, On Tue, Jul 09, 2024 at 01:25:42PM GMT, Josef Bacik wrote: > Add some documentation on the new statmount syscall. > > Signed-off-by: Josef Bacik <josef@toxicpanda.com> It's looking good already. Please see some comments below. Have a lovely day! Alex > --- > man/man2/statmount.2 | 280 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 280 insertions(+) > create mode 100644 man/man2/statmount.2 > > diff --git a/man/man2/statmount.2 b/man/man2/statmount.2 > new file mode 100644 > index 000000000..c437ea685 > --- /dev/null > +++ b/man/man2/statmount.2 > @@ -0,0 +1,280 @@ > +'\" t > +.\" Copyright (c) 2024 Josef Bacik <josef@toxicpanda.com> > +.\" > +.\" SPDX-License-Identifier: Linux-man-pages-copyleft > +.\" > +.TH statmount 2 (date) "Linux man-pages (unreleased)" > +.SH NAME > +statmount \- get a mount status > +.SH LIBRARY > +Standard C library > +.RI ( libc ", " \-lc ) > +.SH SYNOPSIS > +.nf > +.BR "#include <linux/mount.h>" " /* Definition of STATMOUNT_* constants */" > +.B #include <unistd.h> > +.P > +.BI "int syscall(SYS_statmount, struct mnt_id_req * " req , > +.BI " struct statmount * " smbuf ", size_t " bufsize , > +.BI " unsigned long " flags ); > +.P > +.B #include <linux/mount.h> > +.P > +.B struct mnt_id_req { > +.BR " __u32 size;" " /* sizeof(struct mnt_id_req) */" > +.BR " __u64 mnt_id;" " /* The mnt_id being queried */" > +.BR " __u64 param;" " /* An ORed combination of the STATMOUNT_ constants */" > +.B }; > +.P > +.B struct statmount { > +.B " __u32 size;" > +.B " __u64 mask;" > +.B " __u32 sb_dev_major;" > +.B " __u32 sb_dev_minor;" > +.B " __u64 sb_magic;" > +.B " __u32 sb_flags;" > +.B " __u32 fs_type;" > +.B " __u64 mnt_id;" > +.B " __u64 mnt_parent_id;" > +.B " __u32 mnt_id_old;" > +.B " __u32 mnt_parent_id_old;" > +.B " __u64 mnt_attr;" > +.B " __u64 mnt_propagation;" > +.B " __u64 mnt_peer_group;" > +.B " __u64 mnt_master;" > +.B " __u64 propagate_from;" > +.B " __u32 mnt_root;" > +.B " __u32 mnt_point;" > +.B " char str[];" > +.B }; > +.fi > +.P > +.IR Note : > +glibc provides no wrapper for > +.BR statmount (), > +necessitating the use of > +.BR syscall (2). > +.SH DESCRIPTION > +To access a mount's status, > +the caller must have CAP_SYS_ADMIN in the user namespace. > +.P > +This function returns information about a mount, > +storing it in the buffer pointed to by > +.IR smbuf . > +The returned buffer is a > +.I struct statmount > +which is of size > +.I bufsize > +with the fields filled in as described below. > +.P > +(Note that reserved space and padding is omitted.) > +.SS The mnt_id_req structure > +.I req.size > +is used by the kernel to determine which > +.I struct\~mnt_id_req > +is being passed in; > +it should always be set to > +.IR sizeof(struct\~mnt_id_req) . > +.P > +.I req.mnt_id > +can be obtained from either > +.BR statx (2) > +using > +.B STATX_MNT_ID_UNIQUE > +or from > +.BR listmount (2) > +and is used as the identifier to query the status of the desired mount point. > +.P > +.I req.param > +is used to tell the kernel which fields the caller is interested in. > +It is an ORed combination of the following constants > +.P > +.in +4n > +.TS > +lB l. > +STATMOUNT_SB_BASIC /* Want/got sb_* */ > +STATMOUNT_MNT_BASIC /* Want/got mnt_* */ > +STATMOUNT_PROPAGATE_FROM /* Want/got propagate_from */ > +STATMOUNT_MNT_ROOT /* Want/got mnt_root */ > +STATMOUNT_MNT_POINT /* Want/got mnt_point */ > +STATMOUNT_FS_TYPE /* Want/got fs_type */ > +.TE > +.in > +.P > +In general, > +the kernel does > +.I not > +reject values in > +.I req.param > +other than the above. > +(For an exception, > +see > +.B EINVAL > +in errors.) > +Instead, > +it simply informs the caller which values are supported > +by this kernel and filesystem via the > +.I statmount.mask > +field. > +Therefore, > +.I "do not" > +simply set > +.I req.param > +to > +.B UINT_MAX > +(all bits set), > +as one or more bits may, > +in the future, > +be used to specify an extension to the buffer. > +.SS The returned information > +The status information for the target mount is returned in the > +.I statmount > +structure pointed to by > +.IR smbuf . > +.P > +The fields in the > +.I statmount > +structure are: > +.TP > +.I smbuf.size > +The size of the returned > +.I smbuf > +structure, > +including any of the strings fields that were filled. > +.TP > +.I smbuf.mask > +The ORed combination of > +.BI STATMOUNT_ * > +flags indicating which fields were filled in and thus valid. > +The kernel may return fields that weren't requested, > +and may fail to return fields that were requested, > +depending on what the backing file system and kernel supports. > +In either case, > +.I req.param > +will not be equal to > +.IR mask . > +.TP > +.I smbuf.sb_dev_major > +.TQ > +.I smbuf.sb_dev_minor > +The device that is mounted at this mount point. > +.TP > +.I smbuf.sb_magic > +The file system specific super block magic. > +.TP > +.I smbuf.sb_flags > +The flags that are set on the super block, > +an ORed combination of > +.BR SB_RDONLY , > +.BR SB_SYNCHRONOUS , > +.BR SB_DIRSYNC , > +.BR SB_LAZYTIME . > +.TP > +.I smbuf.fs_type > +The offset to the location in the > +.I smbuf.str > +buffer that contains the string representation of the mounted file system. > +It is a null-terminated string. > +.TP > +.I smbuf.mnt_id > +The unique mount ID of the mount. > +.TP > +.I smbuf.mnt_parent_id > +The unique mount ID of the parent mount point of this mount. > +If this is the root mount point then > +.IR smbuf.mnt_id\~==\~smbuf.parent_mount_id . > +.TP > +.I smbuf.mnt_id_old > +This corresponds to the mount ID that is exported by > +.IR /proc/ pid /mountinfo . > +.TP > +.I smbuf.mnt_parent_id_old > +This corresponds to the parent mount ID that is exported by > +.IR /proc/ pid /mountinfo . > +.TP > +.I smbuf.mnt_attr > +The > +.BI MOUNT_ATTR_ * > +flags set on this mount point. > +.TP > +.I smbuf.mnt_propagation > +The mount propagation flags, > +which can be one of > +.BR MS_SHARED , > +.BR MS_SLAVE , > +.BR MS_PRIVATE , > +.BR MS_UNBINDABLE . > +.TP > +.I smbuf.mnt_peer_group > +The ID of the shared peer group. > +.TP > +.I smbuf.mnt_master > +The mount point receives its propagation from this mount ID. > +.TP > +.I smbuf.propagate_from > +The ID from the namespace we propagated from. > +.TP > +.I smbuf.mnt_root > +The offset to the location in the > +.I smbuf.str > +buffer that contains the string representation of the mount > +relative to the root of the file system. > +It is a NULL terminated string. s/NULL terminated/null-terminated/ NULL is the null pointer constant. NUL is the ASCII name for the null byte. We say null-terminated, because someone (probably Michael Kerrisk) thought NULL and NUL were confusing. :) > +.TP > +.I smbuf.mnt_point > +The offset to the location in the > +.I smbuf.str > +buffer that contains the string representation of the mount > +relative to the current root (ie if you are in a > +.BR chroot ). > +It is a NULL terminated string. s/NULL terminated/null-terminated/ > +.SH RETURN VALUE > +On success, zero is returned. > +On error, \-1 is returned, and > +.I errno > +is set to indicate the error. > +.SH ERRORS > +.TP > +.B EPERM > +Permission is denied for accessing this mount. > +.TP > +.B EFAULT > +.I req > +or > +.I smbuf > +is NULL or points to a location outside the process's NULL actually points to a location outside the accessible address space. We can simplify and not mention NULL. Normally, I use the _Nullable qualifier on function prototypes that accept NULL. See for example recvfrom(2). If it's not used, passing NULL is Undefined Behavior. > +accessible address space. > +.TP > +.B EINVAL > +Invalid flag specified in > +.IR flags . > +.TP > +.B EINVAL > +.I req > +is of insufficient size to be utilized. .TP > +.B E2BIG > +.I req > +is too large. > +.TP > +.B EOVERFLOW > +The size of > +.I smbuf > +is too small to contain either the > +.IR smbuf.fs_type , > +.IR smbuf.mnt_root , > +or > +.IR smbuf.mnt_point . > +Allocate a larger buffer and retry the call. > +.TP > +.B ENOENT > +The specified > +.I req.mnt_id > +doesn't exist. > +.TP > +.B ENOMEM > +Out of memory (i.e., kernel memory). > +.SH STANDARDS > +Linux. > +.SH SEE ALSO > +.BR listmount (2), > +.BR statx (2) > -- > 2.43.0 >
On Tue, Jul 09, 2024 at 07:48:54PM +0200, Alejandro Colomar wrote: > Hi Josef, > > On Tue, Jul 09, 2024 at 01:25:42PM GMT, Josef Bacik wrote: > > Add some documentation on the new statmount syscall. > > > > Signed-off-by: Josef Bacik <josef@toxicpanda.com> > > It's looking good already. Please see some comments below. > > Have a lovely day! > Alex > > > --- > > man/man2/statmount.2 | 280 +++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 280 insertions(+) > > create mode 100644 man/man2/statmount.2 > > > > diff --git a/man/man2/statmount.2 b/man/man2/statmount.2 > > new file mode 100644 > > index 000000000..c437ea685 > > --- /dev/null > > +++ b/man/man2/statmount.2 > > @@ -0,0 +1,280 @@ > > +'\" t > > +.\" Copyright (c) 2024 Josef Bacik <josef@toxicpanda.com> > > +.\" > > +.\" SPDX-License-Identifier: Linux-man-pages-copyleft > > +.\" > > +.TH statmount 2 (date) "Linux man-pages (unreleased)" > > +.SH NAME > > +statmount \- get a mount status > > +.SH LIBRARY > > +Standard C library > > +.RI ( libc ", " \-lc ) > > +.SH SYNOPSIS > > +.nf > > +.BR "#include <linux/mount.h>" " /* Definition of STATMOUNT_* constants */" > > +.B #include <unistd.h> > > +.P > > +.BI "int syscall(SYS_statmount, struct mnt_id_req * " req , > > +.BI " struct statmount * " smbuf ", size_t " bufsize , > > +.BI " unsigned long " flags ); > > +.P > > +.B #include <linux/mount.h> > > +.P > > +.B struct mnt_id_req { > > +.BR " __u32 size;" " /* sizeof(struct mnt_id_req) */" > > +.BR " __u64 mnt_id;" " /* The mnt_id being queried */" > > +.BR " __u64 param;" " /* An ORed combination of the STATMOUNT_ constants */" > > +.B }; > > +.P > > +.B struct statmount { > > +.B " __u32 size;" > > +.B " __u64 mask;" > > +.B " __u32 sb_dev_major;" > > +.B " __u32 sb_dev_minor;" > > +.B " __u64 sb_magic;" > > +.B " __u32 sb_flags;" > > +.B " __u32 fs_type;" > > +.B " __u64 mnt_id;" > > +.B " __u64 mnt_parent_id;" > > +.B " __u32 mnt_id_old;" > > +.B " __u32 mnt_parent_id_old;" > > +.B " __u64 mnt_attr;" > > +.B " __u64 mnt_propagation;" > > +.B " __u64 mnt_peer_group;" > > +.B " __u64 mnt_master;" > > +.B " __u64 propagate_from;" > > +.B " __u32 mnt_root;" > > +.B " __u32 mnt_point;" > > +.B " char str[];" > > +.B }; > > +.fi > > +.P > > +.IR Note : > > +glibc provides no wrapper for > > +.BR statmount (), > > +necessitating the use of > > +.BR syscall (2). > > +.SH DESCRIPTION > > +To access a mount's status, > > +the caller must have CAP_SYS_ADMIN in the user namespace. > > +.P > > +This function returns information about a mount, > > +storing it in the buffer pointed to by > > +.IR smbuf . > > +The returned buffer is a > > +.I struct statmount > > +which is of size > > +.I bufsize > > +with the fields filled in as described below. > > +.P > > +(Note that reserved space and padding is omitted.) > > +.SS The mnt_id_req structure > > +.I req.size > > +is used by the kernel to determine which > > +.I struct\~mnt_id_req > > +is being passed in; > > +it should always be set to > > +.IR sizeof(struct\~mnt_id_req) . > > +.P > > +.I req.mnt_id > > +can be obtained from either > > +.BR statx (2) > > +using > > +.B STATX_MNT_ID_UNIQUE > > +or from > > +.BR listmount (2) > > +and is used as the identifier to query the status of the desired mount point. > > +.P > > +.I req.param > > +is used to tell the kernel which fields the caller is interested in. > > +It is an ORed combination of the following constants > > +.P > > +.in +4n > > +.TS > > +lB l. > > +STATMOUNT_SB_BASIC /* Want/got sb_* */ > > +STATMOUNT_MNT_BASIC /* Want/got mnt_* */ > > +STATMOUNT_PROPAGATE_FROM /* Want/got propagate_from */ > > +STATMOUNT_MNT_ROOT /* Want/got mnt_root */ > > +STATMOUNT_MNT_POINT /* Want/got mnt_point */ > > +STATMOUNT_FS_TYPE /* Want/got fs_type */ > > +.TE > > +.in > > +.P > > +In general, > > +the kernel does > > +.I not > > +reject values in > > +.I req.param > > +other than the above. > > +(For an exception, > > +see > > +.B EINVAL > > +in errors.) > > +Instead, > > +it simply informs the caller which values are supported > > +by this kernel and filesystem via the > > +.I statmount.mask > > +field. > > +Therefore, > > +.I "do not" > > +simply set > > +.I req.param > > +to > > +.B UINT_MAX > > +(all bits set), > > +as one or more bits may, > > +in the future, > > +be used to specify an extension to the buffer. > > +.SS The returned information > > +The status information for the target mount is returned in the > > +.I statmount > > +structure pointed to by > > +.IR smbuf . > > +.P > > +The fields in the > > +.I statmount > > +structure are: > > +.TP > > +.I smbuf.size > > +The size of the returned > > +.I smbuf > > +structure, > > +including any of the strings fields that were filled. > > +.TP > > +.I smbuf.mask > > +The ORed combination of > > +.BI STATMOUNT_ * > > +flags indicating which fields were filled in and thus valid. > > +The kernel may return fields that weren't requested, > > +and may fail to return fields that were requested, > > +depending on what the backing file system and kernel supports. > > +In either case, > > +.I req.param > > +will not be equal to > > +.IR mask . > > +.TP > > +.I smbuf.sb_dev_major > > +.TQ > > +.I smbuf.sb_dev_minor > > +The device that is mounted at this mount point. > > +.TP > > +.I smbuf.sb_magic > > +The file system specific super block magic. > > +.TP > > +.I smbuf.sb_flags > > +The flags that are set on the super block, > > +an ORed combination of > > +.BR SB_RDONLY , > > +.BR SB_SYNCHRONOUS , > > +.BR SB_DIRSYNC , > > +.BR SB_LAZYTIME . > > +.TP > > +.I smbuf.fs_type > > +The offset to the location in the > > +.I smbuf.str > > +buffer that contains the string representation of the mounted file system. > > +It is a null-terminated string. > > +.TP > > +.I smbuf.mnt_id > > +The unique mount ID of the mount. > > +.TP > > +.I smbuf.mnt_parent_id > > +The unique mount ID of the parent mount point of this mount. > > +If this is the root mount point then > > +.IR smbuf.mnt_id\~==\~smbuf.parent_mount_id . > > +.TP > > +.I smbuf.mnt_id_old > > +This corresponds to the mount ID that is exported by > > +.IR /proc/ pid /mountinfo . > > +.TP > > +.I smbuf.mnt_parent_id_old > > +This corresponds to the parent mount ID that is exported by > > +.IR /proc/ pid /mountinfo . > > +.TP > > +.I smbuf.mnt_attr > > +The > > +.BI MOUNT_ATTR_ * > > +flags set on this mount point. > > +.TP > > +.I smbuf.mnt_propagation > > +The mount propagation flags, > > +which can be one of > > +.BR MS_SHARED , > > +.BR MS_SLAVE , > > +.BR MS_PRIVATE , > > +.BR MS_UNBINDABLE . > > +.TP > > +.I smbuf.mnt_peer_group > > +The ID of the shared peer group. > > +.TP > > +.I smbuf.mnt_master > > +The mount point receives its propagation from this mount ID. > > +.TP > > +.I smbuf.propagate_from > > +The ID from the namespace we propagated from. > > +.TP > > +.I smbuf.mnt_root > > +The offset to the location in the > > +.I smbuf.str > > +buffer that contains the string representation of the mount > > +relative to the root of the file system. > > +It is a NULL terminated string. > > s/NULL terminated/null-terminated/ > > NULL is the null pointer constant. > NUL is the ASCII name for the null byte. > We say null-terminated, because someone (probably Michael Kerrisk) > thought NULL and NUL were confusing. :) > This is probably worth adding to 'make check' to save you time from telling me to do that when I screw it up again in the future. Thanks, Josef
On Tue, Jul 09, 2024 at 02:37:24PM GMT, Josef Bacik wrote: > > s/NULL terminated/null-terminated/ > > > > NULL is the null pointer constant. > > NUL is the ASCII name for the null byte. > > We say null-terminated, because someone (probably Michael Kerrisk) > > thought NULL and NUL were confusing. :) > > > > This is probably worth adding to 'make check' to save you time from telling me > to do that when I screw it up again in the future. Thanks, Hmmmm, interesting. Maybe I can come up with some rules for common mistakes. Cheers, Alex > > Josef >
diff --git a/man/man2/statmount.2 b/man/man2/statmount.2 new file mode 100644 index 000000000..c437ea685 --- /dev/null +++ b/man/man2/statmount.2 @@ -0,0 +1,280 @@ +'\" t +.\" Copyright (c) 2024 Josef Bacik <josef@toxicpanda.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH statmount 2 (date) "Linux man-pages (unreleased)" +.SH NAME +statmount \- get a mount status +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.BR "#include <linux/mount.h>" " /* Definition of STATMOUNT_* constants */" +.B #include <unistd.h> +.P +.BI "int syscall(SYS_statmount, struct mnt_id_req * " req , +.BI " struct statmount * " smbuf ", size_t " bufsize , +.BI " unsigned long " flags ); +.P +.B #include <linux/mount.h> +.P +.B struct mnt_id_req { +.BR " __u32 size;" " /* sizeof(struct mnt_id_req) */" +.BR " __u64 mnt_id;" " /* The mnt_id being queried */" +.BR " __u64 param;" " /* An ORed combination of the STATMOUNT_ constants */" +.B }; +.P +.B struct statmount { +.B " __u32 size;" +.B " __u64 mask;" +.B " __u32 sb_dev_major;" +.B " __u32 sb_dev_minor;" +.B " __u64 sb_magic;" +.B " __u32 sb_flags;" +.B " __u32 fs_type;" +.B " __u64 mnt_id;" +.B " __u64 mnt_parent_id;" +.B " __u32 mnt_id_old;" +.B " __u32 mnt_parent_id_old;" +.B " __u64 mnt_attr;" +.B " __u64 mnt_propagation;" +.B " __u64 mnt_peer_group;" +.B " __u64 mnt_master;" +.B " __u64 propagate_from;" +.B " __u32 mnt_root;" +.B " __u32 mnt_point;" +.B " char str[];" +.B }; +.fi +.P +.IR Note : +glibc provides no wrapper for +.BR statmount (), +necessitating the use of +.BR syscall (2). +.SH DESCRIPTION +To access a mount's status, +the caller must have CAP_SYS_ADMIN in the user namespace. +.P +This function returns information about a mount, +storing it in the buffer pointed to by +.IR smbuf . +The returned buffer is a +.I struct statmount +which is of size +.I bufsize +with the fields filled in as described below. +.P +(Note that reserved space and padding is omitted.) +.SS The mnt_id_req structure +.I req.size +is used by the kernel to determine which +.I struct\~mnt_id_req +is being passed in; +it should always be set to +.IR sizeof(struct\~mnt_id_req) . +.P +.I req.mnt_id +can be obtained from either +.BR statx (2) +using +.B STATX_MNT_ID_UNIQUE +or from +.BR listmount (2) +and is used as the identifier to query the status of the desired mount point. +.P +.I req.param +is used to tell the kernel which fields the caller is interested in. +It is an ORed combination of the following constants +.P +.in +4n +.TS +lB l. +STATMOUNT_SB_BASIC /* Want/got sb_* */ +STATMOUNT_MNT_BASIC /* Want/got mnt_* */ +STATMOUNT_PROPAGATE_FROM /* Want/got propagate_from */ +STATMOUNT_MNT_ROOT /* Want/got mnt_root */ +STATMOUNT_MNT_POINT /* Want/got mnt_point */ +STATMOUNT_FS_TYPE /* Want/got fs_type */ +.TE +.in +.P +In general, +the kernel does +.I not +reject values in +.I req.param +other than the above. +(For an exception, +see +.B EINVAL +in errors.) +Instead, +it simply informs the caller which values are supported +by this kernel and filesystem via the +.I statmount.mask +field. +Therefore, +.I "do not" +simply set +.I req.param +to +.B UINT_MAX +(all bits set), +as one or more bits may, +in the future, +be used to specify an extension to the buffer. +.SS The returned information +The status information for the target mount is returned in the +.I statmount +structure pointed to by +.IR smbuf . +.P +The fields in the +.I statmount +structure are: +.TP +.I smbuf.size +The size of the returned +.I smbuf +structure, +including any of the strings fields that were filled. +.TP +.I smbuf.mask +The ORed combination of +.BI STATMOUNT_ * +flags indicating which fields were filled in and thus valid. +The kernel may return fields that weren't requested, +and may fail to return fields that were requested, +depending on what the backing file system and kernel supports. +In either case, +.I req.param +will not be equal to +.IR mask . +.TP +.I smbuf.sb_dev_major +.TQ +.I smbuf.sb_dev_minor +The device that is mounted at this mount point. +.TP +.I smbuf.sb_magic +The file system specific super block magic. +.TP +.I smbuf.sb_flags +The flags that are set on the super block, +an ORed combination of +.BR SB_RDONLY , +.BR SB_SYNCHRONOUS , +.BR SB_DIRSYNC , +.BR SB_LAZYTIME . +.TP +.I smbuf.fs_type +The offset to the location in the +.I smbuf.str +buffer that contains the string representation of the mounted file system. +It is a null-terminated string. +.TP +.I smbuf.mnt_id +The unique mount ID of the mount. +.TP +.I smbuf.mnt_parent_id +The unique mount ID of the parent mount point of this mount. +If this is the root mount point then +.IR smbuf.mnt_id\~==\~smbuf.parent_mount_id . +.TP +.I smbuf.mnt_id_old +This corresponds to the mount ID that is exported by +.IR /proc/ pid /mountinfo . +.TP +.I smbuf.mnt_parent_id_old +This corresponds to the parent mount ID that is exported by +.IR /proc/ pid /mountinfo . +.TP +.I smbuf.mnt_attr +The +.BI MOUNT_ATTR_ * +flags set on this mount point. +.TP +.I smbuf.mnt_propagation +The mount propagation flags, +which can be one of +.BR MS_SHARED , +.BR MS_SLAVE , +.BR MS_PRIVATE , +.BR MS_UNBINDABLE . +.TP +.I smbuf.mnt_peer_group +The ID of the shared peer group. +.TP +.I smbuf.mnt_master +The mount point receives its propagation from this mount ID. +.TP +.I smbuf.propagate_from +The ID from the namespace we propagated from. +.TP +.I smbuf.mnt_root +The offset to the location in the +.I smbuf.str +buffer that contains the string representation of the mount +relative to the root of the file system. +It is a NULL terminated string. +.TP +.I smbuf.mnt_point +The offset to the location in the +.I smbuf.str +buffer that contains the string representation of the mount +relative to the current root (ie if you are in a +.BR chroot ). +It is a NULL terminated string. +.SH RETURN VALUE +On success, zero is returned. +On error, \-1 is returned, and +.I errno +is set to indicate the error. +.SH ERRORS +.TP +.B EPERM +Permission is denied for accessing this mount. +.TP +.B EFAULT +.I req +or +.I smbuf +is NULL or points to a location outside the process's +accessible address space. +.TP +.B EINVAL +Invalid flag specified in +.IR flags . +.TP +.B EINVAL +.I req +is of insufficient size to be utilized. +.B E2BIG +.I req +is too large. +.TP +.B EOVERFLOW +The size of +.I smbuf +is too small to contain either the +.IR smbuf.fs_type , +.IR smbuf.mnt_root , +or +.IR smbuf.mnt_point . +Allocate a larger buffer and retry the call. +.TP +.B ENOENT +The specified +.I req.mnt_id +doesn't exist. +.TP +.B ENOMEM +Out of memory (i.e., kernel memory). +.SH STANDARDS +Linux. +.SH SEE ALSO +.BR listmount (2), +.BR statx (2)
Add some documentation on the new statmount syscall. Signed-off-by: Josef Bacik <josef@toxicpanda.com> --- man/man2/statmount.2 | 280 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 280 insertions(+) create mode 100644 man/man2/statmount.2