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 +propagate to or from replicated subtrees. +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 .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. +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. .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 +(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 +subtree, but mounts made underneath this subtree will not be propagated +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. -- 2.8.2 -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
