Hello Omar, Thanks for tackling this. Some comments below. On 05/18/2016 08:57 PM, Omar Sandoval wrote: > From: Omar Sandoval <osandov@xxxxxx> > > This stuff is all documented in the kernel source tree under > Documentation/filesystems/sharedsubtree.txt, so let's document it > properly for users. > > Signed-off-by: Omar Sandoval <osandov@xxxxxx> > --- > man2/mount.2 | 133 +++++++++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 88 insertions(+), 45 deletions(-) > > diff --git a/man2/mount.2 b/man2/mount.2 > index aa6558a87cd9..419e22da800f 100644 > --- a/man2/mount.2 > +++ b/man2/mount.2 > @@ -83,44 +83,6 @@ and various mount flags > .\" (as defined in \fI<linux/fs.h>\fP for libc4 and libc5 > .\" and in \fI<sys/mount.h>\fP for glibc2) > in the low order 16 bits: > -.\" FIXME 2.6.15 added flags for "shared subtree" functionality: > -.\" > -.\" MS_PRIVATE > -.\" All mounts are private by default. Previously shared mounts > -.\" can be re-marked PRIVATE. > -.\" MS_SHARED > -.\" Mount points that are marked SHARED propagate mount events > -.\" to one another after being cloned. > -.\" mount --make-rshared ==> MS_SHARED | MS_REC > -.\" MS_SLAVE > -.\" A previously shared mount point can be marked SLAVE, meaning > -.\" it receives propagated events, but does not propagate events. > -.\" MS_UNBINDABLE > -.\" mounts cannot be bound into other places, and will not be > -.\" propagated into new subtrees > -.\" > -.\" These settings are visible in /proc/$$/mountinfo > -.\" > -.\" These need to be documented on this page. > -.\" See: > -.\" > -.\" * Documentation/filesystems/sharedsubtree.txt > -.\" > -.\" * http://lwn.net/Articles/159077/ > -.\" > -.\" * https://www.kernel.org/doc/ols/2006/ols2006v2-pages-209-222.pdf > -.\" Shared-Subtree Concept, Implementation, and Applications in Linux > -.\" Al Viro viro@xxxxxxxxxxxxxxxx > -.\" Ram Pai linuxram@xxxxxxxxxx > -.\" > -.\" * http://www.ibm.com/developerworks/linux/library/l-mount-namespaces/index.html > -.\" Applying mount namespaces > -.\" > -.\" Uncover practical applications for advanced Linux mounts features > -.\" Serge E. Hallyn (sergeh@xxxxxxxxxx), Software Engineer, IBM > -.\" Ram Pai (linuxram@xxxxxxxxxx), Software Engineer, IBM > -.\" Date: 17 Sep 2007 > -.\" > .\" FIXME 2.6.25 Added MS_I_VERSION, which needs to be documented. > .\" > .TP > @@ -240,12 +202,34 @@ programs from this filesystem. > .\" (This is a security feature to prevent users executing set-user-ID and > .\" set-group-ID programs from removable disk devices.) > .TP > +.BR MS_PRIVATE " (since Linux 2.6.15)" > +Set the mount propagation on this mountpoint to private. Mounts will not s/mountpoint/mount point/ (all occurrences) Change "this mountpoint" to the .I target mount point (and other instances below). > +propagate to or from replicated subtrees. What is a "replicated subtree"? This isn't explained in the text (and, doesn't feel quite right as a term, but perhaps that is just because you do not explain what you mean). > +This flag can only be combined with s/can only be combined with/ can be combined with only/ (all occurrences) > +.B MS_REC > +and > +.BR MS_SILENT . > +The > +.IR source , > +.IR filesystemtype , > +and > +.IR data > +arguments are ignored. > +.TP > .B MS_RDONLY > Mount filesystem read-only. > -.\" > -.\" FIXME Document MS_REC, available since 2.4.11. > -.\" This flag has meaning in conjunction with MS_BIND and > -.\" also with the shared subtree flags. > +.TP > +.BR MS_REC " (since Linux 2.4.11)" > +When passed together with > +.BR MS_BIND , > +recursively bind mount all mountpoints underneath the source subtree. Change "source subtree" to .I source subtree. > +When passed together with a shared subtree flag (one of > +.BR MS_PRIVATE , > +.BR MS_SHARED , > +.BR MS_SLAVE ", or" > +.BR MS_UNBINDABLE ), > +recursively apply the shared subtree setting to all mountpoints > +underneath the target subtree. Change "target subtree" to .I target subtree. > .TP > .BR MS_RELATIME " (since Linux 2.6.20)" > When a file on this filesystem is accessed, > @@ -306,6 +290,21 @@ and, additionally, before kernel 2.4.10, the following could also be changed: > .BR MS_NODEV , > .BR MS_NOEXEC . > .TP > +.BR MS_SHARED " (since Linux 2.6.15)" > +Set the mount propagation on this mountpoint to shared. > +Mounts will be propagated to and from replicated subtrees s/Mount/Mount and unmount events/ > +(i.e., all replicas will continue to be the same). > +This flag can only be combined with > +.B MS_REC > +and > +.BR MS_SILENT . > +The > +.IR source , > +.IR filesystemtype , > +and > +.IR data > +arguments are ignored. > +.TP > .BR MS_SILENT " (since Linux 2.6.17)" > Suppress the display of certain > .RI ( printk ()) > @@ -314,6 +313,28 @@ This flag supersedes the misnamed and obsolete > .BR MS_VERBOSE > flag (available since Linux 2.4.12), which has the same meaning. > .TP > +.BR MS_SLAVE " (since Linux 2.6.15)" > +Make this mountpoint a slave of its source mountpoint, referred to as > +its master. > +Mounts made underneath the master subtree will be propagated to this s/Mounts made/Mount and unmount events/ > +subtree, but mounts made underneath this subtree will not be propagated s/mounts made/events/ > +back to the master. > +Note that a slave mountpoint can still have either private propagation > +(see > +.BR MS_PRIVATE ) > +or shared propagation (see > +.BR MS_SHARED ). > +This flag can only be combined with > +.B MS_REC > +and > +.BR MS_SILENT . > +The > +.IR source , > +.IR filesystemtype , > +and > +.IR data > +arguments are ignored. > +.TP > .BR MS_STRICTATIME " (since Linux 2.6.30)" > Always update the last access time (atime) when files on this > filesystem are accessed. > @@ -331,6 +352,21 @@ the > flag to > .BR open (2) > was specified for all file opens to this filesystem). > +.TP > +.BR MS_UNBINDABLE " (since Linux 2.6.15)" > +Set the mount propagation on this mountpoint to private (see > +.BR MS_PRIVATE ) > +and disallow bind mounts with this mountpoint as the source. > +This flag can only be combined with > +.B MS_REC > +and > +.BR MS_SILENT . > +The > +.IR source , > +.IR filesystemtype , > +and > +.IR data > +arguments are ignored. > .PP > From Linux 2.4 onward, the > .BR MS_NODEV ", " MS_NOEXEC ", and " MS_NOSUID > @@ -408,6 +444,11 @@ Or, a move > was attempted, but > .I source > was not a mount point, or was \(aq/\(aq. > +Or, more than one shared subtree flag was given. > +Or, a shared subtree flag was combined with a flag other than > +.B MS_REC > +or > +.BR MS_SILENT . > .TP > .B ELOOP > Too many links encountered during pathname resolution. > @@ -457,11 +498,13 @@ The definitions of > .BR MS_MOVE , > .BR MS_REC , > .BR MS_RELATIME , > +.BR MS_STRICTATIME , > +.BR MS_PRIVATE , > +.BR MS_SHARED , > +.BR MS_SLAVE , > and > -.BR MS_STRICTATIME > +.BR MS_UNBINDABLE > were added to glibc headers in version 2.12. > -.\" FIXME . Definitions of the so-far-undocumented MS_UNBINDABLE, MS_PRIVATE, > -.\" MS_SHARED, and MS_SLAVE were (also) only added to glibc headers in 2.12. > .SH CONFORMING TO > This function is Linux-specific and should not be used in > programs intended to be portable. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
