Re: [patch 1/4][resend] fuse-procfs: proxy proc files

Re: [patch 1/4][resend] fuse-procfs: proxy proc files

[Serge E. Hallyn]

Quoting Daniel Lezcano (daniel.lezcano-GANU6spQydw@public.gmane.org):
> This patch makes possible to mount the fuse-procfs on top of /proc
> and display the content of /proc via fuse.
> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano-GANU6spQydw@public.gmane.org>

Thanks, Daniel.  This is neat.  How were you thinking of
configuring this?  A config file read at mount?

Actually one question I have is:

> +static int procfs_read(const char *path, char *buf, size_t size,
> +		      off_t offset, struct fuse_file_info *fi)
> +{
> +	int ret;
> +	struct procfs_file *pfile = (typeof(pfile))fi->fh;;
> +
> +	switch (pfile->type) {
> +
> +	case PROCFS_PROXY:
> +		ret = read(pfile->file.proxy.fd, buf, size);

Are you supposed to do something with the offset?  I don't see
any seek method in fuse_operations, does fuse keep the fp
internally and send it along as offset to read?

> +		if (ret < 0)
> +			return -errno;
> +		break;
> +	}
> +
> +	return ret;
> +}

-serge

Re: [patch 1/4][resend] fuse-procfs: proxy proc files

[Krzysztof Taraszka]

Hi Daniel,

right now I do not have any new tasks so I can take a look your patches
and... they won't to apply (patches from 2 to 4).
Can you send me your current procfs.c single file with patches added?

Thanks

-- 
K

2009/9/4 Daniel Lezcano <daniel.lezcano-GANU6spQydw@public.gmane.org>

> This patch makes possible to mount the fuse-procfs on top of /proc
> and display the content of /proc via fuse.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano-GANU6spQydw@public.gmane.org>
> ---
>  procfs.c |  246
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 246 insertions(+)
>
> Index: lxcfs/procfs.c
> ===================================================================
> --- /dev/null
> +++ lxcfs/procfs.c
> @@ -0,0 +1,246 @@
> +
> +#include <fuse.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <libgen.h>
> +#include <errno.h>
> +#include <dirent.h>
> +#include <mntent.h>
> +#include <limits.h>
> +#include <fcntl.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <sys/param.h>
> +
> +enum {
> +       PROCFS_PROXY,
> +};
> +
> +struct procfs_info {
> +       DIR *procdir;
> +       DIR *subdir;
> +};
> +
> +struct proxy_file {
> +       int fd;
> +};
> +
> +struct procfs_file {
> +       int type;
> +       union {
> +               struct proxy_file proxy;
> +       } file;
> +};
> +
> +static int procfs_readlink(const char *path, char *buf, size_t bufsiz)
> +{
> +       struct fuse_context *context = fuse_get_context();
> +       struct procfs_info *fsinfo = context->private_data;
> +       char *bname = strchr(path, '/');
> +       int ret;
> +
> +       if (strcmp(path, "/"))
> +               bname += 1;
> +
> +       ret = readlinkat(dirfd(fsinfo->procdir), bname, buf, bufsiz);
> +       if (ret < 0)
> +               return -errno;
> +
> +       buf[ret] = '\0';
> +
> +       return 0;
> +}
> +
> +static int procfs_getattr(const char *path, struct stat *stbuf)
> +{
> +       struct fuse_context *context = fuse_get_context();
> +       struct procfs_info *fsinfo = context->private_data;
> +       char *bname = strchr(path, '/');
> +
> +       if (strcmp(path, "/"))
> +               bname += 1;
> +
> +       if (fstatat(dirfd(fsinfo->procdir), bname, stbuf,
> AT_SYMLINK_NOFOLLOW))
> +               return -errno;
> +
> +       return 0;
> +}
> +
> +static int procfs_open(const char *path, struct fuse_file_info *fi)
> +{
> +       struct fuse_context *context = fuse_get_context();
> +       struct procfs_info *fsinfo = context->private_data;
> +       char *bname = strchr(path, '/');
> +       struct procfs_file *pfile;
> +
> +       if (strcmp(path, "/"))
> +               bname += 1;
> +
> +       pfile = malloc(sizeof(*pfile));
> +       if (!pfile)
> +               return -ENOMEM;
> +
> +       pfile->type = PROCFS_PROXY;
> +       pfile->file.proxy.fd = openat(dirfd(fsinfo->procdir), bname,
> fi->flags);
> +       if (pfile->file.proxy.fd < 0) {
> +               free(pfile);
> +               return -errno;
> +       }
> +
> +       fi->fh = (typeof(fi->fh))pfile;
> +
> +       return 0;
> +}
> +
> +static int procfs_read(const char *path, char *buf, size_t size,
> +                     off_t offset, struct fuse_file_info *fi)
> +{
> +       int ret;
> +       struct procfs_file *pfile = (typeof(pfile))fi->fh;;
> +
> +       switch (pfile->type) {
> +
> +       case PROCFS_PROXY:
> +               ret = read(pfile->file.proxy.fd, buf, size);
> +               if (ret < 0)
> +                       return -errno;
> +               break;
> +       }
> +
> +       return ret;
> +}
> +
> +static int procfs_write(const char *path, const char *buf, size_t size,
> +                      off_t offset, struct fuse_file_info *fi)
> +{
> +       int ret;
> +       struct procfs_file *pfile = (typeof(pfile))fi->fh;;
> +
> +       switch (pfile->type) {
> +
> +       case PROCFS_PROXY:
> +               ret = write(pfile->file.proxy.fd, buf, size);
> +               if (ret < 0)
> +                       return -errno;
> +               break;
> +       }
> +
> +       return ret;
> +}
> +
> +static int procfs_release(const char *path, struct fuse_file_info *fi)
> +{
> +       struct procfs_file *pfile = (typeof(pfile))fi->fh;;
> +
> +       switch (pfile->type) {
> +
> +       case PROCFS_PROXY:
> +               if (close(pfile->file.proxy.fd))
> +                       return -errno;
> +               break;
> +       }
> +
> +       return 0;
> +}
> +
> +static int procfs_opendir(const char *path, struct fuse_file_info *fi)
> +{
> +       struct fuse_context *context = fuse_get_context();
> +       struct procfs_info *fsinfo = context->private_data;
> +       char *bname = strchr(path, '/');
> +       int fd;
> +
> +       if (!strcmp(path, "/")) {
> +               fsinfo->subdir = fsinfo->procdir;
> +               return 0;
> +       }
> +
> +       fd = openat(dirfd(fsinfo->procdir), bname + 1, O_DIRECTORY);
> +       if (fd < 0)
> +               return -errno;
> +
> +       fsinfo->subdir = fdopendir(fd);
> +
> +       return 0;
> +}
> +
> +static int procfs_readdir(const char *path, void *buf, fuse_fill_dir_t
> filler,
> +                        off_t offset, struct fuse_file_info *fi)
> +{
> +       struct fuse_context *context = fuse_get_context();
> +       struct procfs_info *fsinfo = context->private_data;
> +        struct dirent dirent, *direntp;
> +
> +       if (!offset)
> +               rewinddir(fsinfo->subdir);
> +
> +        while (!readdir_r(fsinfo->subdir, &dirent, &direntp) && direntp)
> +               if (filler(buf, direntp->d_name, NULL, offset++))
> +                       break;
> +
> +       return 0;
> +}
> +
> +static int procfs_releasedir(const char *path, struct fuse_file_info *fi)
> +{
> +       struct fuse_context *context = fuse_get_context();
> +       struct procfs_info *fsinfo = context->private_data;
> +       DIR *subdir = fsinfo->subdir;
> +
> +       fsinfo->subdir = NULL;
> +       if (subdir && subdir != fsinfo->procdir)
> +               closedir(subdir);
> +
> +       return 0;
> +}
> +
> +static void *procfs_init(struct fuse_conn_info *conn)
> +{
> +       struct procfs_info *fsinfo;
> +
> +       fsinfo = malloc(sizeof(*fsinfo));
> +       if (!fsinfo)
> +               return NULL;
> +
> +       fsinfo->procdir = opendir("/proc");
> +       if (!fsinfo->procdir)
> +               goto out_free_fsinfo;
> +
> +       fsinfo->subdir = NULL;
> +out:
> +       return fsinfo;
> +
> +out_free_fsinfo:
> +       free(fsinfo);
> +       fsinfo = NULL;
> +       goto out;
> +}
> +
> +static void procfs_destroy(void *private_data)
> +{
> +       struct procfs_info *fsinfo = private_data;
> +
> +       closedir(fsinfo->procdir);
> +       free(fsinfo);
> +}
> +
> +static struct fuse_operations procfs_ops = {
> +       .readlink   = procfs_readlink,
> +       .getattr    = procfs_getattr,
> +       .open       = procfs_open,
> +       .read       = procfs_read,
> +       .write      = procfs_write,
> +       .opendir    = procfs_opendir,
> +       .releasedir = procfs_releasedir,
> +       .readdir    = procfs_readdir,
> +       .release    = procfs_release,
> +       .init       = procfs_init,
> +       .destroy    = procfs_destroy,
> +};
> +
> +int main(int argc, char *argv[])
> +{
> +       return fuse_main(argc, argv, &procfs_ops, NULL);
> +}
>
>

Re: [patch 1/4][resend] fuse-procfs: proxy proc files

[Daniel Lezcano]

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Krzysztof Taraszka wrote:
> Hi Daniel,
>
> right now I do not have any new tasks so I can take a look your patches
> and... they won't to apply (patches from 2 to 4).
> Can you send me your current procfs.c single file with patches added?
>
> Thanks
>   
Sure, in attachment the procfs.tar.gz which is a directory containing 
the patches.
Just untar and quilt push -a.

  -- Daniel



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Re: [patch 1/4][resend] fuse-procfs: proxy proc files

[Krzysztof Taraszka]

Thank you Daniel.
I have a little problem with fuse and containers. Do I have to add the fuse
device to the container?
When I tried to mount procfs I received:

container2:/# ./procfs -odirect_io /proc/meminfo
fuse: device not found, try 'modprobe fuse' first

The fuse module was loaded on host. What I did wrong? I am asking because I
am working around user space scripts for managing lxc (written in bash,
init.d script, few lxc-create-* scripts based on distro, etc) and I would
like to add this development future to this scripts.
Right now I have few nice and good looking userspace scripts.
Would be great If I may do the deb and rpm package with lxc user scripts and
lxc-tools or add my scripts to lxc-tools tree.

More about that in this week in the different thread. Hope you will give me
the direction guys.


2009/9/14 Daniel Lezcano <daniel.lezcano-GANU6spQydw@public.gmane.org>

> Krzysztof Taraszka wrote:
>
>> Hi Daniel,
>>
>> right now I do not have any new tasks so I can take a look your patches
>> and... they won't to apply (patches from 2 to 4).
>> Can you send me your current procfs.c single file with patches added?
>>
>> Thanks
>>
>>
> Sure, in attachment the procfs.tar.gz which is a directory containing the
> patches.
> Just untar and quilt push -a.
>
>  -- Daniel
>
>
>

Re: [patch 1/4][resend] fuse-procfs: proxy proc files

[Daniel Lezcano]

Krzysztof Taraszka wrote:
> Thank you Daniel.
> I have a little problem with fuse and containers. Do I have to add the fuse
> device to the container?
> When I tried to mount procfs I received:
>
> container2:/# ./procfs -odirect_io /proc/meminfo
> fuse: device not found, try 'modprobe fuse' first
>
> The fuse module was loaded on host. What I did wrong? I am asking because I
> am working around user space scripts for managing lxc (written in bash,
> init.d script, few lxc-create-* scripts based on distro, etc) and I would
> like to add this development future to this scripts.
> Right now I have few nice and good looking userspace scripts.
> Would be great If I may do the deb and rpm package with lxc user scripts and
> lxc-tools or add my scripts to lxc-tools tree.
>   
Let's see :)

> More about that in this week in the different thread. Hope you will give me
> the direction guys.
>   

I think the command line is not right. Fuse uses at the /proc directory 
when initializating, so that have to be done in two steps:

Can you try:

lxc-execute -n foo /bin/bash

(from the shell in the container):
procfs -o direct_io /tmp/<tmpdir>
mount --bind /tmp/<tmpdir> /proc
echo 268435456 > /cgroup/foo/memory.memsw.limit_in_bytes
echo 268435456 > /cgroup/foo/memory.limit_in_bytes

* before exiting the container:
umount /proc
fusermount -u /tmp/<tmpfile>

If you do 'ls /proc', you should see everything expect the /proc/sys 
directory.
If you do 'cat /proc/meminfo', you should see:
MemTotal: 262144 kB
MemFree: 250684 kB
SwapTotal: 262144 kB
SwapFree: 0 kB