[PATCH v2 09/10] man/man2/statmount.2: Document req.mnt_ns_fd
From: Bhavik Sachdev <hidden>
Date: 2026-02-22 14:52:28
Subsystem:
the rest · Maintainer:
Linus Torvalds
Document the new mnt_ns_fd parameter to struct mnt_id_req. req.mnt_ns_fd can be used to query for a mount in a foreign mount namespace. The mnt_ns_fd parameter description is based on this commit message [1]. Link [1]: <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9020d0d844ad58a051f90b1e5b82ba34123925b9> Signed-off-by: Bhavik Sachdev <redacted> --- man/man2/statmount.2 | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/man/man2/statmount.2 b/man/man2/statmount.2
index 7951c8391..0b3a65bb3 100644
--- a/man/man2/statmount.2
+++ b/man/man2/statmount.2@@ -24,6 +24,7 @@ .SH SYNOPSIS .EX .B struct mnt_id_req { .BR " __u32 size;" " /* sizeof(struct mnt_id_req) */" +.BR " __u32 mnt_ns_fd;" " /* fd of mnt_ns to query the mnt_id in */" .BR " __u64 mnt_id;" " /* The mnt_id being queried */" .BR " __u64 param;" " /* An ORed combination of the STATMOUNT_ constants */" .BR " __u32 mnt_ns_id;" " /* The id of mnt_ns to query the mnt_id in */"
@@ -74,7 +75,9 @@ .SH DESCRIPTION To access a mount's status, the caller must have CAP_SYS_ADMIN in the user namespace. In case of accessing a mount in a foreign mount namespace (specified via -.IR req.mnt_ns_id ), +.I req.mnt_ns_id +or +.IR req.mnt_ns_fd ), the foreign mount namespace should be child of the current namespace. .P This function returns information about a mount,
@@ -97,6 +100,16 @@ .SS The mnt_id_req structure it should always be set to .IR sizeof(struct\~mnt_id_req) . .P +.I req.mnt_ns_fd +can be obtained from +.B PIDFD_GET_MNT_NAMESPACE +.BR ioctl (2) +operation or by opening a file descriptor to +.IR /proc/ pid /ns/mnt +and is used to specify a foreign mount namespace in which to query +.I req.mnt_id +(Since Linux 6.18). +.P .I req.mnt_id can be obtained from either .BR statx (2)
@@ -372,6 +385,13 @@ .SH ERRORS .I req is of insufficient size to be utilized. .TP +.B EINVAL +Both +.I req.mnt_ns_id +and +.I req.mnt_ns_fd +were set. +.TP .B E2BIG .I req is too large.
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2.53.0