From: Randy Dunlap <[email protected]>
Make smount.c source file and add that to Makefile so that its
build can be checked.
Signed-off-by: Randy Dunlap <[email protected]>
cc: Miklos Szeredi <[email protected]>
---
Documentation/Makefile | 2
Documentation/filesystems/00-INDEX | 2
Documentation/filesystems/Makefile | 8 ++
Documentation/filesystems/sharedsubtree.txt | 82 +---------------------------
Documentation/filesystems/smount.c | 73 ++++++++++++++++++++++++
5 files changed, 88 insertions(+), 79 deletions(-)
--- /dev/null
+++ lin2627-rc3g4-kerndoc/Documentation/filesystems/smount.c
@@ -0,0 +1,73 @@
+//
+//this code was developed my Miklos Szeredi <[email protected]>
+//and modified by Ram Pai <[email protected]>
+// sample usage:
+// smount /tmp shared
+//
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/fsuid.h>
+
+#ifndef MS_REC
+#define MS_REC 0x4000 /* 16384: Recursive loopback */
+#endif
+
+#ifndef MS_SHARED
+#define MS_SHARED 1<<20 /* Shared */
+#endif
+
+#ifndef MS_PRIVATE
+#define MS_PRIVATE 1<<18 /* Private */
+#endif
+
+#ifndef MS_SLAVE
+#define MS_SLAVE 1<<19 /* Slave */
+#endif
+
+#ifndef MS_UNBINDABLE
+#define MS_UNBINDABLE 1<<17 /* Unbindable */
+#endif
+
+int main(int argc, char *argv[])
+{
+ int type;
+ if(argc != 3) {
+ fprintf(stderr, "usage: %s dir "
+ "<rshared|rslave|rprivate|runbindable|shared|slave"
+ "|private|unbindable>\n" , argv[0]);
+ return 1;
+ }
+
+ fprintf(stdout, "%s %s %s\n", argv[0], argv[1], argv[2]);
+
+ if (strcmp(argv[2],"rshared")==0)
+ type=(MS_SHARED|MS_REC);
+ else if (strcmp(argv[2],"rslave")==0)
+ type=(MS_SLAVE|MS_REC);
+ else if (strcmp(argv[2],"rprivate")==0)
+ type=(MS_PRIVATE|MS_REC);
+ else if (strcmp(argv[2],"runbindable")==0)
+ type=(MS_UNBINDABLE|MS_REC);
+ else if (strcmp(argv[2],"shared")==0)
+ type=MS_SHARED;
+ else if (strcmp(argv[2],"slave")==0)
+ type=MS_SLAVE;
+ else if (strcmp(argv[2],"private")==0)
+ type=MS_PRIVATE;
+ else if (strcmp(argv[2],"unbindable")==0)
+ type=MS_UNBINDABLE;
+ else {
+ fprintf(stderr, "invalid operation: %s\n", argv[2]);
+ return 1;
+ }
+ setfsuid(getuid());
+
+ if(mount("", argv[1], "dontcare", type, "") == -1) {
+ perror("mount");
+ return 1;
+ }
+ return 0;
+}
--- lin2627-rc3g4-kerndoc.orig/Documentation/filesystems/sharedsubtree.txt
+++ lin2627-rc3g4-kerndoc/Documentation/filesystems/sharedsubtree.txt
@@ -47,6 +47,7 @@ replicas continue to be exactly same.
note: mount command does not yet support the --make-shared flag.
I have included a small C program which does the same by executing
'smount /mnt shared'
+ [see Documentation/filesystems/smount.c]
#mount --bind /mnt /tmp
The above command replicates the mount at /mnt to the mountpoint /tmp
@@ -141,87 +142,12 @@ replicas continue to be exactly same.
Currently the mount command is not aware of shared subtree features.
Work is in progress to add the support in mount ( util-linux package ).
- Till then use the following program.
+ Until then use the 'smount' program that is located in
+ "Documentation/filesystems/smount.c" and build it like:
- ------------------------------------------------------------------------
- //
- //this code was developed my Miklos Szeredi <[email protected]>
- //and modified by Ram Pai <[email protected]>
- // sample usage:
- // smount /tmp shared
- //
- #include <stdio.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include <string.h>
- #include <sys/mount.h>
- #include <sys/fsuid.h>
-
- #ifndef MS_REC
- #define MS_REC 0x4000 /* 16384: Recursive loopback */
- #endif
-
- #ifndef MS_SHARED
- #define MS_SHARED 1<<20 /* Shared */
- #endif
-
- #ifndef MS_PRIVATE
- #define MS_PRIVATE 1<<18 /* Private */
- #endif
-
- #ifndef MS_SLAVE
- #define MS_SLAVE 1<<19 /* Slave */
- #endif
-
- #ifndef MS_UNBINDABLE
- #define MS_UNBINDABLE 1<<17 /* Unbindable */
- #endif
-
- int main(int argc, char *argv[])
- {
- int type;
- if(argc != 3) {
- fprintf(stderr, "usage: %s dir "
- "<rshared|rslave|rprivate|runbindable|shared|slave"
- "|private|unbindable>\n" , argv[0]);
- return 1;
- }
-
- fprintf(stdout, "%s %s %s\n", argv[0], argv[1], argv[2]);
-
- if (strcmp(argv[2],"rshared")==0)
- type=(MS_SHARED|MS_REC);
- else if (strcmp(argv[2],"rslave")==0)
- type=(MS_SLAVE|MS_REC);
- else if (strcmp(argv[2],"rprivate")==0)
- type=(MS_PRIVATE|MS_REC);
- else if (strcmp(argv[2],"runbindable")==0)
- type=(MS_UNBINDABLE|MS_REC);
- else if (strcmp(argv[2],"shared")==0)
- type=MS_SHARED;
- else if (strcmp(argv[2],"slave")==0)
- type=MS_SLAVE;
- else if (strcmp(argv[2],"private")==0)
- type=MS_PRIVATE;
- else if (strcmp(argv[2],"unbindable")==0)
- type=MS_UNBINDABLE;
- else {
- fprintf(stderr, "invalid operation: %s\n", argv[2]);
- return 1;
- }
- setfsuid(getuid());
-
- if(mount("", argv[1], "dontcare", type, "") == -1) {
- perror("mount");
- return 1;
- }
- return 0;
- }
- -----------------------------------------------------------------------
-
- Copy the above code snippet into smount.c
gcc -o smount smount.c
+ -----------------------------------------------------------------------
(i) To mark all the mounts under /mnt as shared execute the following
command:
--- lin2627-rc3g4-kerndoc.orig/Documentation/Makefile
+++ lin2627-rc3g4-kerndoc/Documentation/Makefile
@@ -1,3 +1,3 @@
obj-m := DocBook/ accounting/ auxdisplay/ connector/ \
- filesystems/configfs/ ia64/ networking/ \
+ filesystems/ filesystems/configfs/ ia64/ networking/ \
pcmcia/ spi/ video4linux/ vm/ watchdog/src/
--- /dev/null
+++ lin2627-rc3g4-kerndoc/Documentation/filesystems/Makefile
@@ -0,0 +1,8 @@
+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := smount
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
--- lin2627-rc3g4-kerndoc.orig/Documentation/filesystems/00-INDEX
+++ lin2627-rc3g4-kerndoc/Documentation/filesystems/00-INDEX
@@ -92,6 +92,8 @@ sharedsubtree.txt
- a description of shared subtrees for namespaces.
smbfs.txt
- info on using filesystems with the SMB protocol (Win 3.11 and NT).
+smount.c
+ - sample source code for mounting shared subtrees
spufs.txt
- info and mount options for the SPU filesystem used on Cell.
sysfs-pci.txt
---
~Randy
Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA
http://linuxplumbersconf.org/
On Sun, Aug 17, 2008 at 09:44:42PM -0700, Randy Dunlap wrote:
> From: Randy Dunlap <[email protected]>
>
> Make smount.c source file and add that to Makefile so that its
> build can be checked.
Just remove it, and modern /bin/mount handles shared subtrees just fine
>
> Signed-off-by: Randy Dunlap <[email protected]>
> cc: Miklos Szeredi <[email protected]>
> ---
> Documentation/Makefile | 2
> Documentation/filesystems/00-INDEX | 2
> Documentation/filesystems/Makefile | 8 ++
> Documentation/filesystems/sharedsubtree.txt | 82 +---------------------------
> Documentation/filesystems/smount.c | 73 ++++++++++++++++++++++++
> 5 files changed, 88 insertions(+), 79 deletions(-)
>
> --- /dev/null
> +++ lin2627-rc3g4-kerndoc/Documentation/filesystems/smount.c
> @@ -0,0 +1,73 @@
> +//
> +//this code was developed my Miklos Szeredi <[email protected]>
> +//and modified by Ram Pai <[email protected]>
> +// sample usage:
> +// smount /tmp shared
> +//
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <string.h>
> +#include <sys/mount.h>
> +#include <sys/fsuid.h>
> +
> +#ifndef MS_REC
> +#define MS_REC 0x4000 /* 16384: Recursive loopback */
> +#endif
> +
> +#ifndef MS_SHARED
> +#define MS_SHARED 1<<20 /* Shared */
> +#endif
> +
> +#ifndef MS_PRIVATE
> +#define MS_PRIVATE 1<<18 /* Private */
> +#endif
> +
> +#ifndef MS_SLAVE
> +#define MS_SLAVE 1<<19 /* Slave */
> +#endif
> +
> +#ifndef MS_UNBINDABLE
> +#define MS_UNBINDABLE 1<<17 /* Unbindable */
> +#endif
> +
> +int main(int argc, char *argv[])
> +{
> + int type;
> + if(argc != 3) {
> + fprintf(stderr, "usage: %s dir "
> + "<rshared|rslave|rprivate|runbindable|shared|slave"
> + "|private|unbindable>\n" , argv[0]);
> + return 1;
> + }
> +
> + fprintf(stdout, "%s %s %s\n", argv[0], argv[1], argv[2]);
> +
> + if (strcmp(argv[2],"rshared")==0)
> + type=(MS_SHARED|MS_REC);
> + else if (strcmp(argv[2],"rslave")==0)
> + type=(MS_SLAVE|MS_REC);
> + else if (strcmp(argv[2],"rprivate")==0)
> + type=(MS_PRIVATE|MS_REC);
> + else if (strcmp(argv[2],"runbindable")==0)
> + type=(MS_UNBINDABLE|MS_REC);
> + else if (strcmp(argv[2],"shared")==0)
> + type=MS_SHARED;
> + else if (strcmp(argv[2],"slave")==0)
> + type=MS_SLAVE;
> + else if (strcmp(argv[2],"private")==0)
> + type=MS_PRIVATE;
> + else if (strcmp(argv[2],"unbindable")==0)
> + type=MS_UNBINDABLE;
> + else {
> + fprintf(stderr, "invalid operation: %s\n", argv[2]);
> + return 1;
> + }
> + setfsuid(getuid());
> +
> + if(mount("", argv[1], "dontcare", type, "") == -1) {
> + perror("mount");
> + return 1;
> + }
> + return 0;
> +}
> --- lin2627-rc3g4-kerndoc.orig/Documentation/filesystems/sharedsubtree.txt
> +++ lin2627-rc3g4-kerndoc/Documentation/filesystems/sharedsubtree.txt
> @@ -47,6 +47,7 @@ replicas continue to be exactly same.
> note: mount command does not yet support the --make-shared flag.
> I have included a small C program which does the same by executing
> 'smount /mnt shared'
> + [see Documentation/filesystems/smount.c]
>
> #mount --bind /mnt /tmp
> The above command replicates the mount at /mnt to the mountpoint /tmp
> @@ -141,87 +142,12 @@ replicas continue to be exactly same.
>
> Currently the mount command is not aware of shared subtree features.
> Work is in progress to add the support in mount ( util-linux package ).
> - Till then use the following program.
> + Until then use the 'smount' program that is located in
> + "Documentation/filesystems/smount.c" and build it like:
>
> - ------------------------------------------------------------------------
> - //
> - //this code was developed my Miklos Szeredi <[email protected]>
> - //and modified by Ram Pai <[email protected]>
> - // sample usage:
> - // smount /tmp shared
> - //
> - #include <stdio.h>
> - #include <stdlib.h>
> - #include <unistd.h>
> - #include <string.h>
> - #include <sys/mount.h>
> - #include <sys/fsuid.h>
> -
> - #ifndef MS_REC
> - #define MS_REC 0x4000 /* 16384: Recursive loopback */
> - #endif
> -
> - #ifndef MS_SHARED
> - #define MS_SHARED 1<<20 /* Shared */
> - #endif
> -
> - #ifndef MS_PRIVATE
> - #define MS_PRIVATE 1<<18 /* Private */
> - #endif
> -
> - #ifndef MS_SLAVE
> - #define MS_SLAVE 1<<19 /* Slave */
> - #endif
> -
> - #ifndef MS_UNBINDABLE
> - #define MS_UNBINDABLE 1<<17 /* Unbindable */
> - #endif
> -
> - int main(int argc, char *argv[])
> - {
> - int type;
> - if(argc != 3) {
> - fprintf(stderr, "usage: %s dir "
> - "<rshared|rslave|rprivate|runbindable|shared|slave"
> - "|private|unbindable>\n" , argv[0]);
> - return 1;
> - }
> -
> - fprintf(stdout, "%s %s %s\n", argv[0], argv[1], argv[2]);
> -
> - if (strcmp(argv[2],"rshared")==0)
> - type=(MS_SHARED|MS_REC);
> - else if (strcmp(argv[2],"rslave")==0)
> - type=(MS_SLAVE|MS_REC);
> - else if (strcmp(argv[2],"rprivate")==0)
> - type=(MS_PRIVATE|MS_REC);
> - else if (strcmp(argv[2],"runbindable")==0)
> - type=(MS_UNBINDABLE|MS_REC);
> - else if (strcmp(argv[2],"shared")==0)
> - type=MS_SHARED;
> - else if (strcmp(argv[2],"slave")==0)
> - type=MS_SLAVE;
> - else if (strcmp(argv[2],"private")==0)
> - type=MS_PRIVATE;
> - else if (strcmp(argv[2],"unbindable")==0)
> - type=MS_UNBINDABLE;
> - else {
> - fprintf(stderr, "invalid operation: %s\n", argv[2]);
> - return 1;
> - }
> - setfsuid(getuid());
> -
> - if(mount("", argv[1], "dontcare", type, "") == -1) {
> - perror("mount");
> - return 1;
> - }
> - return 0;
> - }
> - -----------------------------------------------------------------------
> -
> - Copy the above code snippet into smount.c
> gcc -o smount smount.c
>
> + -----------------------------------------------------------------------
>
> (i) To mark all the mounts under /mnt as shared execute the following
> command:
> --- lin2627-rc3g4-kerndoc.orig/Documentation/Makefile
> +++ lin2627-rc3g4-kerndoc/Documentation/Makefile
> @@ -1,3 +1,3 @@
> obj-m := DocBook/ accounting/ auxdisplay/ connector/ \
> - filesystems/configfs/ ia64/ networking/ \
> + filesystems/ filesystems/configfs/ ia64/ networking/ \
> pcmcia/ spi/ video4linux/ vm/ watchdog/src/
> --- /dev/null
> +++ lin2627-rc3g4-kerndoc/Documentation/filesystems/Makefile
> @@ -0,0 +1,8 @@
> +# kbuild trick to avoid linker error. Can be omitted if a module is built.
> +obj- := dummy.o
> +
> +# List of programs to build
> +hostprogs-y := smount
> +
> +# Tell kbuild to always build the programs
> +always := $(hostprogs-y)
> --- lin2627-rc3g4-kerndoc.orig/Documentation/filesystems/00-INDEX
> +++ lin2627-rc3g4-kerndoc/Documentation/filesystems/00-INDEX
> @@ -92,6 +92,8 @@ sharedsubtree.txt
> - a description of shared subtrees for namespaces.
> smbfs.txt
> - info on using filesystems with the SMB protocol (Win 3.11 and NT).
> +smount.c
> + - sample source code for mounting shared subtrees
> spufs.txt
> - info and mount options for the SPU filesystem used on Cell.
> sysfs-pci.txt
>
>
> ---
> ~Randy
> Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA
> http://linuxplumbersconf.org/
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
---end quoted text---
On Mon, 18 Aug 2008 01:04:31 -0400 Christoph Hellwig wrote:
> Just remove it, and modern /bin/mount handles shared subtrees just fine
Miklos... ?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: Randy Dunlap <[email protected]>
mount(8) handles shared subtrees just fine, so remove the smount
program from Documentation/filesystems/sharedsubtree.txt.
Fix annoying "Lets" -> "Let's".
Signed-off-by: Randy Dunlap <[email protected]>
cc: Miklos Szeredi <[email protected]>
---
Documentation/filesystems/sharedsubtree.txt | 192 +++-------------------------
1 file changed, 25 insertions(+), 167 deletions(-)
--- lin2627-rc3g4-kerndoc.orig/Documentation/filesystems/sharedsubtree.txt
+++ lin2627-rc3g4-kerndoc/Documentation/filesystems/sharedsubtree.txt
@@ -41,12 +41,11 @@ replicas continue to be exactly same.
Here is an example:
- Lets say /mnt has a mount that is shared.
+ Let's say /mnt has a mount that is shared.
mount --make-shared /mnt
- note: mount command does not yet support the --make-shared flag.
- I have included a small C program which does the same by executing
- 'smount /mnt shared'
+ Note: mount(8) command now supports the --make-shared flag,
+ so the sample 'smount' program is no longer needed.
#mount --bind /mnt /tmp
The above command replicates the mount at /mnt to the mountpoint /tmp
@@ -58,7 +57,7 @@ replicas continue to be exactly same.
#ls /tmp
a b c
- Now lets say we mount a device at /tmp/a
+ Now let's say we mount a device at /tmp/a
#mount /dev/sd0 /tmp/a
#ls /tmp/a
@@ -80,20 +79,19 @@ replicas continue to be exactly same.
Here is an example:
- Lets say /mnt has a mount which is shared.
+ Let's say /mnt has a mount which is shared.
#mount --make-shared /mnt
- Lets bind mount /mnt to /tmp
+ Let's bind mount /mnt to /tmp
#mount --bind /mnt /tmp
the new mount at /tmp becomes a shared mount and it is a replica of
the mount at /mnt.
- Now lets make the mount at /tmp; a slave of /mnt
+ Now let's make the mount at /tmp; a slave of /mnt
#mount --make-slave /tmp
- [or smount /tmp slave]
- lets mount /dev/sd0 on /mnt/a
+ let's mount /dev/sd0 on /mnt/a
#mount /dev/sd0 /mnt/a
#ls /mnt/a
@@ -104,7 +102,7 @@ replicas continue to be exactly same.
Note the mount event has propagated to the mount at /tmp
- However lets see what happens if we mount something on the mount at /tmp
+ However let's see what happens if we mount something on the mount at /tmp
#mount /dev/sd1 /tmp/b
@@ -124,12 +122,11 @@ replicas continue to be exactly same.
2d) A unbindable mount is a unbindable private mount
- lets say we have a mount at /mnt and we make is unbindable
+ let's say we have a mount at /mnt and we make is unbindable
#mount --make-unbindable /mnt
- [ smount /mnt unbindable ]
- Lets try to bind mount this mount somewhere else.
+ Let's try to bind mount this mount somewhere else.
# mount --bind /mnt /tmp
mount: wrong fs type, bad option, bad superblock on /mnt,
or too many mounted file systems
@@ -139,147 +136,8 @@ replicas continue to be exactly same.
3) smount command
- Currently the mount command is not aware of shared subtree features.
- Work is in progress to add the support in mount ( util-linux package ).
- Till then use the following program.
-
- ------------------------------------------------------------------------
- //
- //this code was developed my Miklos Szeredi <[email protected]>
- //and modified by Ram Pai <[email protected]>
- // sample usage:
- // smount /tmp shared
- //
- #include <stdio.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include <string.h>
- #include <sys/mount.h>
- #include <sys/fsuid.h>
-
- #ifndef MS_REC
- #define MS_REC 0x4000 /* 16384: Recursive loopback */
- #endif
-
- #ifndef MS_SHARED
- #define MS_SHARED 1<<20 /* Shared */
- #endif
-
- #ifndef MS_PRIVATE
- #define MS_PRIVATE 1<<18 /* Private */
- #endif
-
- #ifndef MS_SLAVE
- #define MS_SLAVE 1<<19 /* Slave */
- #endif
-
- #ifndef MS_UNBINDABLE
- #define MS_UNBINDABLE 1<<17 /* Unbindable */
- #endif
-
- int main(int argc, char *argv[])
- {
- int type;
- if(argc != 3) {
- fprintf(stderr, "usage: %s dir "
- "<rshared|rslave|rprivate|runbindable|shared|slave"
- "|private|unbindable>\n" , argv[0]);
- return 1;
- }
-
- fprintf(stdout, "%s %s %s\n", argv[0], argv[1], argv[2]);
-
- if (strcmp(argv[2],"rshared")==0)
- type=(MS_SHARED|MS_REC);
- else if (strcmp(argv[2],"rslave")==0)
- type=(MS_SLAVE|MS_REC);
- else if (strcmp(argv[2],"rprivate")==0)
- type=(MS_PRIVATE|MS_REC);
- else if (strcmp(argv[2],"runbindable")==0)
- type=(MS_UNBINDABLE|MS_REC);
- else if (strcmp(argv[2],"shared")==0)
- type=MS_SHARED;
- else if (strcmp(argv[2],"slave")==0)
- type=MS_SLAVE;
- else if (strcmp(argv[2],"private")==0)
- type=MS_PRIVATE;
- else if (strcmp(argv[2],"unbindable")==0)
- type=MS_UNBINDABLE;
- else {
- fprintf(stderr, "invalid operation: %s\n", argv[2]);
- return 1;
- }
- setfsuid(getuid());
-
- if(mount("", argv[1], "dontcare", type, "") == -1) {
- perror("mount");
- return 1;
- }
- return 0;
- }
- -----------------------------------------------------------------------
-
- Copy the above code snippet into smount.c
- gcc -o smount smount.c
-
-
- (i) To mark all the mounts under /mnt as shared execute the following
- command:
-
- smount /mnt rshared
- the corresponding syntax planned for mount command is
- mount --make-rshared /mnt
-
- just to mark a mount /mnt as shared, execute the following
- command:
- smount /mnt shared
- the corresponding syntax planned for mount command is
- mount --make-shared /mnt
-
- (ii) To mark all the shared mounts under /mnt as slave execute the
- following
-
- command:
- smount /mnt rslave
- the corresponding syntax planned for mount command is
- mount --make-rslave /mnt
-
- just to mark a mount /mnt as slave, execute the following
- command:
- smount /mnt slave
- the corresponding syntax planned for mount command is
- mount --make-slave /mnt
-
- (iii) To mark all the mounts under /mnt as private execute the
- following command:
-
- smount /mnt rprivate
- the corresponding syntax planned for mount command is
- mount --make-rprivate /mnt
-
- just to mark a mount /mnt as private, execute the following
- command:
- smount /mnt private
- the corresponding syntax planned for mount command is
- mount --make-private /mnt
-
- NOTE: by default all the mounts are created as private. But if
- you want to change some shared/slave/unbindable mount as
- private at a later point in time, this command can help.
-
- (iv) To mark all the mounts under /mnt as unbindable execute the
- following
-
- command:
- smount /mnt runbindable
- the corresponding syntax planned for mount command is
- mount --make-runbindable /mnt
-
- just to mark a mount /mnt as unbindable, execute the following
- command:
- smount /mnt unbindable
- the corresponding syntax planned for mount command is
- mount --make-unbindable /mnt
+ Modern mount(8) command is aware of shared subtree features,
+ so use it instead of the 'smount' command. [source code removed]
4) Use cases
@@ -558,7 +416,7 @@ replicas continue to be exactly same.
then the subtree under the unbindable mount is pruned in the new
location.
- eg: lets say we have the following mount tree.
+ eg: let's say we have the following mount tree.
A
/ \
@@ -566,7 +424,7 @@ replicas continue to be exactly same.
/ \ / \
D E F G
- Lets say all the mount except the mount C in the tree are
+ Let's say all the mount except the mount C in the tree are
of a type other than unbindable.
If this tree is rbound to say Z
@@ -683,13 +541,13 @@ replicas continue to be exactly same.
'b' on mounts that receive propagation from mount 'B' and does not have
sub-mounts within them are unmounted.
- Example: Lets say 'B1', 'B2', 'B3' are shared mounts that propagate to
+ Example: Let's say 'B1', 'B2', 'B3' are shared mounts that propagate to
each other.
- lets say 'A1', 'A2', 'A3' are first mounted at dentry 'b' on mount
+ let's say 'A1', 'A2', 'A3' are first mounted at dentry 'b' on mount
'B1', 'B2' and 'B3' respectively.
- lets say 'C1', 'C2', 'C3' are next mounted at the same dentry 'b' on
+ let's say 'C1', 'C2', 'C3' are next mounted at the same dentry 'b' on
mount 'B1', 'B2' and 'B3' respectively.
if 'C1' is unmounted, all the mounts that are most-recently-mounted on
@@ -710,7 +568,7 @@ replicas continue to be exactly same.
A cloned namespace contains all the mounts as that of the parent
namespace.
- Lets say 'A' and 'B' are the corresponding mounts in the parent and the
+ Let's say 'A' and 'B' are the corresponding mounts in the parent and the
child namespace.
If 'A' is shared, then 'B' is also shared and 'A' and 'B' propagate to
@@ -759,11 +617,11 @@ replicas continue to be exactly same.
mount --make-slave /mnt
At this point we have the first mount at /tmp and
- its root dentry is 1. Lets call this mount 'A'
+ its root dentry is 1. Let's call this mount 'A'
And then we have a second mount at /tmp1 with root
- dentry 2. Lets call this mount 'B'
+ dentry 2. Let's call this mount 'B'
Next we have a third mount at /mnt with root dentry
- mnt. Lets call this mount 'C'
+ mnt. Let's call this mount 'C'
'B' is the slave of 'A' and 'C' is a slave of 'B'
A -> B -> C
@@ -794,7 +652,7 @@ replicas continue to be exactly same.
Q3 Why is unbindable mount needed?
- Lets say we want to replicate the mount tree at multiple
+ Let's say we want to replicate the mount tree at multiple
locations within the same subtree.
if one rbind mounts a tree within the same subtree 'n' times
@@ -803,7 +661,7 @@ replicas continue to be exactly same.
mounts. Here is a example.
step 1:
- lets say the root tree has just two directories with
+ let's say the root tree has just two directories with
one vfsmount.
root
/ \
@@ -875,7 +733,7 @@ replicas continue to be exactly same.
Unclonable mounts come in handy here.
step 1:
- lets say the root tree has just two directories with
+ let's say the root tree has just two directories with
one vfsmount.
root
/ \
On Mon, Aug 18, 2008 at 06:14:09PM -0700, Randy Dunlap wrote:
> On Mon, 18 Aug 2008 01:04:31 -0400 Christoph Hellwig wrote:
>
> > Just remove it, and modern /bin/mount handles shared subtrees just fine
>
> Miklos... ?
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> From: Randy Dunlap <[email protected]>
>
> mount(8) handles shared subtrees just fine, so remove the smount
> program from Documentation/filesystems/sharedsubtree.txt.
[...]
> + Note: mount(8) command now supports the --make-shared flag,
Right, ACK ;-)
> #mount --bind /mnt /tmp
BTW, people usually use a space between prompt and command, so:
# mount --bind /mnt /tmp
Karel
--
Karel Zak <[email protected]>
On Mon, 18 Aug 2008, Randy Dunlap wrote:
> On Mon, 18 Aug 2008 01:04:31 -0400 Christoph Hellwig wrote:
>
> > Just remove it, and modern /bin/mount handles shared subtrees just fine
>
> Miklos... ?
Yes, ACK from me too. Thanks Randy!
Miklos
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> From: Randy Dunlap <[email protected]>
>
> mount(8) handles shared subtrees just fine, so remove the smount
> program from Documentation/filesystems/sharedsubtree.txt.
>
> Fix annoying "Lets" -> "Let's".
>
> Signed-off-by: Randy Dunlap <[email protected]>
> cc: Miklos Szeredi <[email protected]>
> ---
> Documentation/filesystems/sharedsubtree.txt | 192 +++-------------------------
> 1 file changed, 25 insertions(+), 167 deletions(-)
>
> --- lin2627-rc3g4-kerndoc.orig/Documentation/filesystems/sharedsubtree.txt
> +++ lin2627-rc3g4-kerndoc/Documentation/filesystems/sharedsubtree.txt
> @@ -41,12 +41,11 @@ replicas continue to be exactly same.
>
> Here is an example:
>
> - Lets say /mnt has a mount that is shared.
> + Let's say /mnt has a mount that is shared.
> mount --make-shared /mnt
>
> - note: mount command does not yet support the --make-shared flag.
> - I have included a small C program which does the same by executing
> - 'smount /mnt shared'
> + Note: mount(8) command now supports the --make-shared flag,
> + so the sample 'smount' program is no longer needed.
>
> #mount --bind /mnt /tmp
> The above command replicates the mount at /mnt to the mountpoint /tmp
> @@ -58,7 +57,7 @@ replicas continue to be exactly same.
> #ls /tmp
> a b c
>
> - Now lets say we mount a device at /tmp/a
> + Now let's say we mount a device at /tmp/a
> #mount /dev/sd0 /tmp/a
>
> #ls /tmp/a
> @@ -80,20 +79,19 @@ replicas continue to be exactly same.
>
> Here is an example:
>
> - Lets say /mnt has a mount which is shared.
> + Let's say /mnt has a mount which is shared.
> #mount --make-shared /mnt
>
> - Lets bind mount /mnt to /tmp
> + Let's bind mount /mnt to /tmp
> #mount --bind /mnt /tmp
>
> the new mount at /tmp becomes a shared mount and it is a replica of
> the mount at /mnt.
>
> - Now lets make the mount at /tmp; a slave of /mnt
> + Now let's make the mount at /tmp; a slave of /mnt
> #mount --make-slave /tmp
> - [or smount /tmp slave]
>
> - lets mount /dev/sd0 on /mnt/a
> + let's mount /dev/sd0 on /mnt/a
> #mount /dev/sd0 /mnt/a
>
> #ls /mnt/a
> @@ -104,7 +102,7 @@ replicas continue to be exactly same.
>
> Note the mount event has propagated to the mount at /tmp
>
> - However lets see what happens if we mount something on the mount at /tmp
> + However let's see what happens if we mount something on the mount at /tmp
>
> #mount /dev/sd1 /tmp/b
>
> @@ -124,12 +122,11 @@ replicas continue to be exactly same.
>
> 2d) A unbindable mount is a unbindable private mount
>
> - lets say we have a mount at /mnt and we make is unbindable
> + let's say we have a mount at /mnt and we make is unbindable
>
> #mount --make-unbindable /mnt
> - [ smount /mnt unbindable ]
>
> - Lets try to bind mount this mount somewhere else.
> + Let's try to bind mount this mount somewhere else.
> # mount --bind /mnt /tmp
> mount: wrong fs type, bad option, bad superblock on /mnt,
> or too many mounted file systems
> @@ -139,147 +136,8 @@ replicas continue to be exactly same.
>
> 3) smount command
>
> - Currently the mount command is not aware of shared subtree features.
> - Work is in progress to add the support in mount ( util-linux package ).
> - Till then use the following program.
> -
> - ------------------------------------------------------------------------
> - //
> - //this code was developed my Miklos Szeredi <[email protected]>
> - //and modified by Ram Pai <[email protected]>
> - // sample usage:
> - // smount /tmp shared
> - //
> - #include <stdio.h>
> - #include <stdlib.h>
> - #include <unistd.h>
> - #include <string.h>
> - #include <sys/mount.h>
> - #include <sys/fsuid.h>
> -
> - #ifndef MS_REC
> - #define MS_REC 0x4000 /* 16384: Recursive loopback */
> - #endif
> -
> - #ifndef MS_SHARED
> - #define MS_SHARED 1<<20 /* Shared */
> - #endif
> -
> - #ifndef MS_PRIVATE
> - #define MS_PRIVATE 1<<18 /* Private */
> - #endif
> -
> - #ifndef MS_SLAVE
> - #define MS_SLAVE 1<<19 /* Slave */
> - #endif
> -
> - #ifndef MS_UNBINDABLE
> - #define MS_UNBINDABLE 1<<17 /* Unbindable */
> - #endif
> -
> - int main(int argc, char *argv[])
> - {
> - int type;
> - if(argc != 3) {
> - fprintf(stderr, "usage: %s dir "
> - "<rshared|rslave|rprivate|runbindable|shared|slave"
> - "|private|unbindable>\n" , argv[0]);
> - return 1;
> - }
> -
> - fprintf(stdout, "%s %s %s\n", argv[0], argv[1], argv[2]);
> -
> - if (strcmp(argv[2],"rshared")==0)
> - type=(MS_SHARED|MS_REC);
> - else if (strcmp(argv[2],"rslave")==0)
> - type=(MS_SLAVE|MS_REC);
> - else if (strcmp(argv[2],"rprivate")==0)
> - type=(MS_PRIVATE|MS_REC);
> - else if (strcmp(argv[2],"runbindable")==0)
> - type=(MS_UNBINDABLE|MS_REC);
> - else if (strcmp(argv[2],"shared")==0)
> - type=MS_SHARED;
> - else if (strcmp(argv[2],"slave")==0)
> - type=MS_SLAVE;
> - else if (strcmp(argv[2],"private")==0)
> - type=MS_PRIVATE;
> - else if (strcmp(argv[2],"unbindable")==0)
> - type=MS_UNBINDABLE;
> - else {
> - fprintf(stderr, "invalid operation: %s\n", argv[2]);
> - return 1;
> - }
> - setfsuid(getuid());
> -
> - if(mount("", argv[1], "dontcare", type, "") == -1) {
> - perror("mount");
> - return 1;
> - }
> - return 0;
> - }
> - -----------------------------------------------------------------------
> -
> - Copy the above code snippet into smount.c
> - gcc -o smount smount.c
> -
> -
> - (i) To mark all the mounts under /mnt as shared execute the following
> - command:
> -
> - smount /mnt rshared
> - the corresponding syntax planned for mount command is
> - mount --make-rshared /mnt
> -
> - just to mark a mount /mnt as shared, execute the following
> - command:
> - smount /mnt shared
> - the corresponding syntax planned for mount command is
> - mount --make-shared /mnt
> -
> - (ii) To mark all the shared mounts under /mnt as slave execute the
> - following
> -
> - command:
> - smount /mnt rslave
> - the corresponding syntax planned for mount command is
> - mount --make-rslave /mnt
> -
> - just to mark a mount /mnt as slave, execute the following
> - command:
> - smount /mnt slave
> - the corresponding syntax planned for mount command is
> - mount --make-slave /mnt
> -
> - (iii) To mark all the mounts under /mnt as private execute the
> - following command:
> -
> - smount /mnt rprivate
> - the corresponding syntax planned for mount command is
> - mount --make-rprivate /mnt
> -
> - just to mark a mount /mnt as private, execute the following
> - command:
> - smount /mnt private
> - the corresponding syntax planned for mount command is
> - mount --make-private /mnt
> -
> - NOTE: by default all the mounts are created as private. But if
> - you want to change some shared/slave/unbindable mount as
> - private at a later point in time, this command can help.
> -
> - (iv) To mark all the mounts under /mnt as unbindable execute the
> - following
> -
> - command:
> - smount /mnt runbindable
> - the corresponding syntax planned for mount command is
> - mount --make-runbindable /mnt
> -
> - just to mark a mount /mnt as unbindable, execute the following
> - command:
> - smount /mnt unbindable
> - the corresponding syntax planned for mount command is
> - mount --make-unbindable /mnt
> + Modern mount(8) command is aware of shared subtree features,
> + so use it instead of the 'smount' command. [source code removed]
>
>
> 4) Use cases
> @@ -558,7 +416,7 @@ replicas continue to be exactly same.
> then the subtree under the unbindable mount is pruned in the new
> location.
>
> - eg: lets say we have the following mount tree.
> + eg: let's say we have the following mount tree.
>
> A
> / \
> @@ -566,7 +424,7 @@ replicas continue to be exactly same.
> / \ / \
> D E F G
>
> - Lets say all the mount except the mount C in the tree are
> + Let's say all the mount except the mount C in the tree are
> of a type other than unbindable.
>
> If this tree is rbound to say Z
> @@ -683,13 +541,13 @@ replicas continue to be exactly same.
> 'b' on mounts that receive propagation from mount 'B' and does not have
> sub-mounts within them are unmounted.
>
> - Example: Lets say 'B1', 'B2', 'B3' are shared mounts that propagate to
> + Example: Let's say 'B1', 'B2', 'B3' are shared mounts that propagate to
> each other.
>
> - lets say 'A1', 'A2', 'A3' are first mounted at dentry 'b' on mount
> + let's say 'A1', 'A2', 'A3' are first mounted at dentry 'b' on mount
> 'B1', 'B2' and 'B3' respectively.
>
> - lets say 'C1', 'C2', 'C3' are next mounted at the same dentry 'b' on
> + let's say 'C1', 'C2', 'C3' are next mounted at the same dentry 'b' on
> mount 'B1', 'B2' and 'B3' respectively.
>
> if 'C1' is unmounted, all the mounts that are most-recently-mounted on
> @@ -710,7 +568,7 @@ replicas continue to be exactly same.
> A cloned namespace contains all the mounts as that of the parent
> namespace.
>
> - Lets say 'A' and 'B' are the corresponding mounts in the parent and the
> + Let's say 'A' and 'B' are the corresponding mounts in the parent and the
> child namespace.
>
> If 'A' is shared, then 'B' is also shared and 'A' and 'B' propagate to
> @@ -759,11 +617,11 @@ replicas continue to be exactly same.
> mount --make-slave /mnt
>
> At this point we have the first mount at /tmp and
> - its root dentry is 1. Lets call this mount 'A'
> + its root dentry is 1. Let's call this mount 'A'
> And then we have a second mount at /tmp1 with root
> - dentry 2. Lets call this mount 'B'
> + dentry 2. Let's call this mount 'B'
> Next we have a third mount at /mnt with root dentry
> - mnt. Lets call this mount 'C'
> + mnt. Let's call this mount 'C'
>
> 'B' is the slave of 'A' and 'C' is a slave of 'B'
> A -> B -> C
> @@ -794,7 +652,7 @@ replicas continue to be exactly same.
>
> Q3 Why is unbindable mount needed?
>
> - Lets say we want to replicate the mount tree at multiple
> + Let's say we want to replicate the mount tree at multiple
> locations within the same subtree.
>
> if one rbind mounts a tree within the same subtree 'n' times
> @@ -803,7 +661,7 @@ replicas continue to be exactly same.
> mounts. Here is a example.
>
> step 1:
> - lets say the root tree has just two directories with
> + let's say the root tree has just two directories with
> one vfsmount.
> root
> / \
> @@ -875,7 +733,7 @@ replicas continue to be exactly same.
> Unclonable mounts come in handy here.
>
> step 1:
> - lets say the root tree has just two directories with
> + let's say the root tree has just two directories with
> one vfsmount.
> root
> / \
>
On Wed, 20 Aug 2008 00:56:25 +0200 Karel Zak wrote:
> On Mon, Aug 18, 2008 at 06:14:09PM -0700, Randy Dunlap wrote:
> > On Mon, 18 Aug 2008 01:04:31 -0400 Christoph Hellwig wrote:
> >
> > > Just remove it, and modern /bin/mount handles shared subtrees just fine
> >
> > Miklos... ?
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > From: Randy Dunlap <[email protected]>
> >
> > mount(8) handles shared subtrees just fine, so remove the smount
> > program from Documentation/filesystems/sharedsubtree.txt.
> [...]
> > + Note: mount(8) command now supports the --make-shared flag,
>
> Right, ACK ;-)
>
> > #mount --bind /mnt /tmp
>
> BTW, people usually use a space between prompt and command, so:
>
> # mount --bind /mnt /tmp
Done for upcoming patch. Thanks.
---
~Randy