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Date: Mon, 18 Aug 2008 01:04:31 -0400
From: Christoph Hellwig <hch@...radead.org>
To: Randy Dunlap <randy.dunlap@...cle.com>
Cc: lkml <linux-kernel@...r.kernel.org>,
akpm <akpm@...ux-foundation.org>, miklos@...redi.hu
Subject: Re: [PATCH 1/2] documentation: split and build smount.c
On Sun, Aug 17, 2008 at 09:44:42PM -0700, Randy Dunlap wrote:
> From: Randy Dunlap <randy.dunlap@...cle.com>
>
> 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 <randy.dunlap@...cle.com>
> cc: Miklos Szeredi <miklos@...redi.hu>
> ---
> 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 <miklos@...redi.hu>
> +//and modified by Ram Pai <linuxram@...ibm.com>
> +// 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 <miklos@...redi.hu>
> - //and modified by Ram Pai <linuxram@...ibm.com>
> - // 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/
> --
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