On Mon, Jul 18, 2011 at 12:06 PM, Sasha Levin <levinsasha928@xxxxxxxxx> wrote:
> This patch adds support to mounting devices using a kernel parameter.
>
> Such feature is usefull for virtual guests. It allows easily automating
> mounts without having to change the base image (which can be read-only).
>
> In /tools/kvm we are interested in such feature to allow us to automatically
> mount user home directory using virtio-9p from the host to the guest
> filesystem under '/hostfs'.
>
> Cc: Avi Kivity <avi@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
Lets CC fsdevel.
> ---
> Documentation/kernel-parameters.txt | 6 +++
> init/do_mounts.c | 61 +++++++++++++++++++++++++++++++++++
> 2 files changed, 67 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index aa47be7..e1955fb 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1476,6 +1476,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> log everything. Information is printed at KERN_DEBUG
> so loglevel=8 may also need to be specified.
>
> + mount=
> + [KNL] Mount a device to a mount point after loading
> + rootfs and setting up devices. Can be used to mount
> + up to 16 devices.
> + Format: <source>,<destination>,<fs>[,<params>]
> +
> mousedev.tap_time=
> [MOUSE] Maximum time between finger touching and
> leaving touchpad surface for touch to be considered
> diff --git a/init/do_mounts.c b/init/do_mounts.c
> index c0851a8..0948f1d 100644
> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -29,9 +29,24 @@ int root_mountflags = MS_RDONLY | MS_SILENT;
> static char * __initdata root_device_name;
> static char __initdata saved_root_name[64];
> static int __initdata root_wait;
> +static char * __initdata user_mount[16];
> +static int __initdata user_mount_count;
>
> dev_t ROOT_DEV;
>
> +static int __init setup_user_mount(char *str)
> +{
> + if (user_mount_count > 15) {
> + printk(KERN_ERR "More than 16 'mount=' options specified.")
> + return 1;
> + }
> +
> + user_mount[user_mount_count++] = str;
> +
> + return 1;
> +}
> +__setup("mount=", setup_user_mount);
> +
> static int __init load_ramdisk(char *str)
> {
> rd_doload = simple_strtol(str,NULL,0) & 3;
> @@ -431,6 +446,51 @@ void __init mount_root(void)
> #endif
> }
>
> +int __init do_user_mounts(void)
> +{
> + int i, res;
> + char *src, *dst, *fs, *params, *cur;
> +
> + for (i = 0; i < user_mount_count; i++) {
> + src = user_mount[i];
> + cur = strstr(user_mount[i], ",");
> + if (!cur)
> + goto fail_str;
> +
> + *cur = '\0';
> + dst = ++cur;
> +
> + cur = strstr(cur, ",");
> + if (!cur)
> + goto fail_str;
> +
> + *cur = '\0';
> + fs = ++cur;
> +
> + cur = strstr(cur, ",");
> + if (cur) {
> + *cur = '\0';
> + params = ++cur;
> + } else {
> + params = NULL;
> + }
> +
> + res = sys_mount(src, dst, fs, 0, params);
> + if (res == 0)
> + printk(KERN_INFO "Mounted (%s filesystem) %s to %s\n",
> + fs, src, dst);
> + else
> + printk(KERN_ERR "Failed mounting (%s filesystem) %s to"
> + " %s. Err: %d\n", fs, src, dst, res);
> + }
> +
> + return 0;
> +
> +fail_str:
> + printk(KERN_ERR "Bad mount str: %s\n", user_mount[i]);
> + return -1;
> +}
> +
> /*
> * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
> */
> @@ -490,4 +550,5 @@ out:
> devtmpfs_mount("dev");
> sys_mount(".", "/", NULL, MS_MOVE, NULL);
> sys_chroot((const char __user __force *)".");
> + do_user_mounts();
> }
> --
> 1.7.6
>
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