fuse-overlayfs.1: regenerate

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

fuse-overlayfs.1

@@ -23,6 +23,10 @@ namespace.
 
 
 .SH OPTIONS
+.PP
+\fB\-\-debug\fP
+Enable debugging mode, can be very noisy.
+
 .PP
 \fB\-o lowerdir=low1[:low2...]\fP
 A list of directories separated by \fB\fC:\fR\&.  Their content is merged.
@@ -37,10 +41,72 @@ done to the file system will be written.
 A directory used internally by fuse\-overlays, must be on the same file
 system as the upper dir.
 
+.PP
+\fB\-o workdir=workdir\fP
+A directory used internally by fuse\-overlays, must be on the same file
+system as the upper dir.
+
+.PP
+\fB\-o uidmapping=UID:MAPPED\-UID:LEN[,UID2:MAPPED\-UID2:LEN2]\fP
+\fB\-o gidmapping=GID:MAPPED\-GID:LEN[,GID2:MAPPED\-GID2:LEN2]\fP
+Specifies the dynamic UID/GID mapping used by fuse\-overlayfs when
+reading/writing files to the system.
+
+.PP
+The fuse\-overlayfs dynamic mapping is an alternative and cheaper way
+to chown'ing the files on the host to accomodate the user namespace
+settings.
+
+.PP
+It is useful to share the same storage among different user namespaces
+and counter effect the mapping done by the user namespace itself, and
+without requiring to chown the files.
+
+.PP
+For example, given on the host two files like:
+
+.PP
+$ stat \-c %u:%g lower/a lower/b
+0:0
+1:1
+
+.PP
+When we run in a user namespace with the following configuration:
+$ cat /proc/self/uid\_map
+         0       1000          1
+         1     110000      65536
+
+.PP
+We would see:
+
+.PP
+$ stat \-c %u:%g merged/a merged/b
+65534:65534
+65534:65534
+
+.PP
+65534 is the overflow id used when the UID/GID is not known inside the
+user namespace.  This happens because both users 0:0 and 1:1 are not
+mapped.
+
+.PP
+In the above example, if we mount the fuse\-overlayfs file system using:
+\fB\fC\-ouidmapping=0:1000:1:1:110000:65536,gidmapping=0:1000:1:1:110000:65536\fR,
+which is the namespace configuration specified on a single line, we'd
+see from the same user namespace:
+
+.PP
+$ stat \-c %u:%g merged/a merged/b
+0:0
+1:1
+
+.PP
+Those are the same IDs visible from outside the user namespace.
+
 
 .SH SEE ALSO
 .PP
-\fBfuse\fP(8), \fBmount\fP(8)
+\fBfuse\fP(8), \fBmount\fP(8), \fBuser\_namespaces\fP(7)
 
 
 .SH AVAILABILITY