My edit is based on experiments and reading Linux code Signed-off-by: Askar Safin <safinaskar@xxxxxxxxxxxx> --- 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 -- 2.47.2
