------------------------------------------------------------------------
Subject:
[PATCH 1/1] mount: shared-subtree support for mount
From:
[EMAIL PROTECTED] (Ram Pai)
Date:
Wed, 19 Apr 2006 12:51:43 -0700 (PDT)
To:
[EMAIL PROTECTED]
To:
[EMAIL PROTECTED]
CC:
[EMAIL PROTECTED]
This patch builds shared-subtree semantics awareness into the mount command.
Updates the man page for mount too.
Signed-off-by: Ram Pai <[EMAIL PROTECTED]>
mount/mount.8 | 35 ++++++++++++++++++++++++++
mount/mount.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++--
mount/mount_constants.h | 12 +++++++++
3 files changed, 109 insertions(+), 2 deletions(-)
Index: util-linux-2.13-pre6/mount/mount.c
===================================================================
--- util-linux-2.13-pre6.orig/mount/mount.c
+++ util-linux-2.13-pre6/mount/mount.c
@@ -72,11 +72,13 @@ int mount_all = 0;
static int optfork = 0;
/* Add volumelabel in a listing of mounted devices (-l). */
static int list_with_volumelabel = 0;
-/* Nonzero for mount {--bind|--replace|--before|--after|--over|--move} */
+/* Nonzero for mount {--bind|--replace|--before|--after|--over|--move|
+ * make-shared|make-private|make-unbindable|make-slave}
+ */
static int mounttype = 0;
/* True if ruid != euid. */
static int suid = 0;
@@ -104,10 +106,11 @@ struct opt_map {
/* Options that we keep the mount system call from seeing. */
#define MS_NOSYS (MS_NOAUTO|MS_USERS|MS_USER|MS_COMMENT|MS_LOOP)
/* Options that we keep from appearing in the options field in the mtab. */
#define MS_NOMTAB (MS_REMOUNT|MS_NOAUTO|MS_USERS|MS_USER)
+#define MS_PROPAGATION (MS_SHARED|MS_SLAVE|MS_UNBINDABLE|MS_PRIVATE)
/* Options that we make ordinary users have by default. */
#define MS_SECURE (MS_NOEXEC|MS_NOSUID|MS_NODEV)
/* Options that we make owner-mounted devices have by default */
@@ -338,10 +341,13 @@ parse_opts (const char *options, int *fl
if (readonly)
*flags |= MS_RDONLY;
if (readwrite)
*flags &= ~MS_RDONLY;
+
+ if (mounttype & MS_PROPAGATION)
+ *flags &= ~MS_BIND;
*flags |= mounttype;
}
/* Try to build a canonical options string. */
static char *
@@ -857,17 +863,19 @@ retry_nfs:
if (fake || mnt5_res == 0) {
/* Mount succeeded, report this (if verbose) and write mtab entry. */
if (loop)
opt_loopdev = loopdev;
- update_mtab_entry(loop ? loopfile : spec,
+ if (!(mounttype & MS_PROPAGATION)) {
+ update_mtab_entry(loop ? loopfile : spec,
node,
types ? types : "unknown",
fix_opts_string (flags & ~MS_NOMTAB, extra_opts, user),
flags,
freq,
pass);
+ }
block_signals (SIG_UNBLOCK);
res = 0;
goto out;
}
@@ -1402,10 +1410,18 @@ static struct option longopts[] = {
{ "before", 0, 0, 131 },
{ "over", 0, 0, 132 },
{ "move", 0, 0, 133 },
{ "guess-fstype", 1, 0, 134 },
{ "rbind", 0, 0, 135 },
+ { "make-shared", 0, 0, 136 },
+ { "make-slave", 0, 0, 137 },
+ { "make-private", 0, 0, 138 },
+ { "make-unbindable", 0, 0, 139 },
+ { "make-rshared", 0, 0, 140 },
+ { "make-rslave", 0, 0, 141 },
+ { "make-rprivate", 0, 0, 142 },
+ { "make-runbindable", 0, 0, 143 },
{ "internal-only", 0, 0, 'i' },
{ NULL, 0, 0, 0 }
};
/* Keep the usage message at max 22 lines, each at most 70 chars long.
@@ -1428,10 +1444,21 @@ usage (FILE *fp, int n) {
"a filesystem (of the given type) found on the device.\n"
"One can also mount an already visible directory tree elsewhere:\n"
" mount --bind olddir newdir\n"
"or move a subtree:\n"
" mount --move olddir newdir\n"
+ "One can change the type of mount containing the directory dir:\n"
+ " mount --make-shared dir\n"
+ " mount --make-slave dir\n"
+ " mount --make-private dir\n"
+ " mount --make-unbindable dir\n"
+ "One can change the type of all the mounts in a mount subtree\n"
+ "containing the directory dir:\n"
+ " mount --make-rshared dir\n"
+ " mount --make-rslave dir\n"
+ " mount --make-rprivate dir\n"
+ " mount --make-runbindable dir\n"
"A device can be given by name, say /dev/hda1 or /dev/cdrom,\n"
"or by label, using -L label or by uuid, using -U uuid .\n"
"Other options: [-nfFrsvw] [-o options] [-p passwdfd].\n"
"For many more details, say man 8 mount .\n"
));
@@ -1579,10 +1606,43 @@ main(int argc, char *argv[]) {
exit(fstype ? 0 : EX_FAIL);
}
case 135:
mounttype = (MS_BIND | MS_REC);
break;
+
+ case 136:
+ mounttype = MS_SHARED;
+ break;
+
+ case 137:
+ mounttype = MS_SLAVE;
+ break;
+
+ case 138:
+ mounttype = MS_PRIVATE;
+ break;
+
+ case 139:
+ mounttype = MS_UNBINDABLE;
+ break;
+
+ case 140:
+ mounttype = (MS_SHARED | MS_REC);
+ break;
+
+ case 141:
+ mounttype = (MS_SLAVE | MS_REC);
+ break;
+
+ case 142:
+ mounttype = (MS_PRIVATE | MS_REC);
+ break;
+
+ case 143:
+ mounttype = (MS_UNBINDABLE | MS_REC);
+ break;
+
case '?':
default:
usage (stderr, EX_USAGE);
}
}
Index: util-linux-2.13-pre6/mount/mount_constants.h
===================================================================
--- util-linux-2.13-pre6.orig/mount/mount_constants.h
+++ util-linux-2.13-pre6/mount/mount_constants.h
@@ -55,10 +55,22 @@ if we have a stack or plain mount - moun
#define MS_REC 0x4000 /* 16384: Recursive loopback */
#endif
#ifndef MS_VERBOSE
#define MS_VERBOSE 0x8000 /* 32768 */
#endif
+#ifndef MS_UNBINDABLE
+#define MS_UNBINDABLE (1<<17) /* 131072 unbindable*/
+#endif
+#ifndef MS_PRIVATE
+#define MS_PRIVATE (1<<18) /* 262144 Private*/
+#endif
+#ifndef MS_SLAVE
+#define MS_SLAVE (1<<19) /* 524288 Slave*/
+#endif
+#ifndef MS_SHARED
+#define MS_SHARED (1<<20) /* 1048576 Shared*/
+#endif
/*
* Magic mount flag number. Had to be or-ed to the flag values.
*/
#ifndef MS_MGC_VAL
#define MS_MGC_VAL 0xC0ED0000 /* magic flag number to indicate "new" flags */
Index: util-linux-2.13-pre6/mount/mount.8
===================================================================
--- util-linux-2.13-pre6.orig/mount/mount.8
+++ util-linux-2.13-pre6/mount/mount.8
@@ -129,10 +129,45 @@ to another place. The call is
.RS
.br
.B "mount --move olddir newdir"
.RE
+Since Linux 2.6.15 it is possible to mark a mount and its submounts as shared,
+private, slave or unbindable. A shared mount provides ability to create mirrors
+of that mount such that mounts and umounts within any of the mirrors propagate
+to the other mirror. A slave mount receives propagation from its master, but
+any not vice-versa. A private mount carries no propagation abilities. A
+unbindable mount is a private mount which cannot cloned through a bind
+operation. Detailed semantics is documented in Documentation/sharedsubtree.txt
+file in the kernel source tree.
+.RS
+.br
+.B "mount --make-shared mountpoint"
+.br
+.B "mount --make-slave mountpoint"
+.br
+.B "mount --make-private mountpoint"
+.br
+.B "mount --make-unbindable mountpoint"
+.br
+.RE
+
+The following commands allows one to recursively change the type of all the
+mounts under a given mountpoint.
+.RS
+.br
+.B "mount --make-rshared mountpoint"
+.br
+.B "mount --make-rslave mountpoint"
+.br
+.B "mount --make-rprivate mountpoint"
+.br
+.B
+"mount --make-runbindable mountpoint"
+.br
+.RE
+
The
.I proc
file system is not associated with a special device, and when
mounting it, an arbitrary keyword, such as
.I proc
------------------------------------------------------------------------
--
redhat-lspp mailing list
[email protected]
https://www.redhat.com/mailman/listinfo/redhat-lspp
