[PATCH v2 1/1] man2/mount.2: expand and clarify docs for MS_REMOUNT | MS_BIND
From: Askar Safin <hidden>
Date: 2025-08-25 15:49:46
Also in:
linux-api, linux-man
Subsystem:
the rest · Maintainer:
Linus Torvalds
My edit is based on experiments and reading Linux code Signed-off-by: Askar Safin <redacted> --- man/man2/mount.2 | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-)
diff --git a/man/man2/mount.2 b/man/man2/mount.2
index 5d83231f9..47fc2d21f 100644
--- a/man/man2/mount.2
+++ b/man/man2/mount.2@@ -405,7 +405,30 @@ flag can be used with to modify only the per-mount-point flags. .\" See https://lwn.net/Articles/281157/ This is particularly useful for setting or clearing the "read-only" -flag on a mount without changing the underlying filesystem. +flag on a mount without changing the underlying filesystem parameters. +The +.I data +argument is ignored if +.B MS_REMOUNT +and +.B MS_BIND +are specified. +Note that the mountpoint will +have its existing per-mount-point flags +cleared and replaced with those in +.I mountflags +when +.B MS_REMOUNT +and +.B MS_BIND +are specified. +This means that if +you wish to preserve +any existing per-mount-point flags, +you need to include them in +.IR mountflags , +along with the per-mount-point flags you wish to set +(or with the flags you wish to clear missing). Specifying .I mountflags as:
@@ -416,8 +439,11 @@ MS_REMOUNT | MS_BIND | MS_RDONLY .EE .in .P -will make access through this mountpoint read-only, without affecting -other mounts. +will make access through this mountpoint read-only +(clearing all other per-mount-point flags), +without affecting +other mounts +of this filesystem. .\" .SS Creating a bind mount If
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2.47.2