linux-kernel - Re: [PATCH 04/14] pstore: Implement show

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Date:   Wed, 5 Jul 2017 10:10:59 -0700
From:   Kees Cook <keescook@...omium.org>
To:     David Howells <dhowells@...hat.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>, Tony Luck <tony.luck@...el.com>,
        Anton Vorontsov <anton@...msg.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Colin Cross <ccross@...roid.com>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH 04/14] pstore: Implement show_options

On Wed, Jul 5, 2017 at 8:24 AM, David Howells <dhowells@...hat.com> wrote:
> Implement the show_options superblock op for pstore as part of a bid to get
> rid of s_options and generic_show_options() to make it easier to implement
> a context-based mount where the mount options can be passed individually
> over a file descriptor.
>
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: Kees Cook <keescook@...omium.org>
> cc: Anton Vorontsov <anton@...msg.org>
> cc: Colin Cross <ccross@...roid.com>
> cc: Tony Luck <tony.luck@...el.com>

Acked-by: Kees Cook <keescook@...omium.org>

Do you want me to take this into the pstore tree or do you want to
push it via a separate tree?

-Kees

> ---
>
>  fs/pstore/inode.c    |   14 +++++++++++---
>  fs/pstore/internal.h |    3 +++
>  fs/pstore/platform.c |    2 +-
>  3 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
> index 792a4e5f9226..913e839ac1f5 100644
> --- a/fs/pstore/inode.c
> +++ b/fs/pstore/inode.c
> @@ -283,6 +283,16 @@ static void parse_options(char *options)
>         }
>  }
>
> +/*
> + * Display the mount options in /proc/mounts.
> + */
> +static int pstore_show_options(struct seq_file *m, struct dentry *root)
> +{
> +       if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
> +               seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
> +       return 0;
> +}
> +
>  static int pstore_remount(struct super_block *sb, int *flags, char *data)
>  {
>         sync_filesystem(sb);
> @@ -296,7 +306,7 @@ static const struct super_operations pstore_ops = {
>         .drop_inode     = generic_delete_inode,
>         .evict_inode    = pstore_evict_inode,
>         .remount_fs     = pstore_remount,
> -       .show_options   = generic_show_options,
> +       .show_options   = pstore_show_options,
>  };
>
>  static struct super_block *pstore_sb;
> @@ -448,8 +458,6 @@ static int pstore_fill_super(struct super_block *sb, void *data, int silent)
>  {
>         struct inode *inode;
>
> -       save_mount_options(sb, data);
> -
>         pstore_sb = sb;
>
>         sb->s_maxbytes          = MAX_LFS_FILESIZE;
> diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
> index c416e653dc4f..4d5913130580 100644
> --- a/fs/pstore/internal.h
> +++ b/fs/pstore/internal.h
> @@ -5,6 +5,9 @@
>  #include <linux/time.h>
>  #include <linux/pstore.h>
>
> +#define PSTORE_DEFAULT_KMSG_BYTES 10240
> +extern unsigned long kmsg_bytes;
> +
>  #ifdef CONFIG_PSTORE_FTRACE
>  extern void pstore_register_ftrace(void);
>  extern void pstore_unregister_ftrace(void);
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index d468eec9b8a6..6640df40908d 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -99,7 +99,7 @@ static char *big_oops_buf;
>  static size_t big_oops_buf_sz;
>
>  /* How much of the console log to snapshot */
> -static unsigned long kmsg_bytes = 10240;
> +unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
>
>  void pstore_set_kmsg_bytes(int bytes)
>  {
>



-- 
Kees Cook
Pixel Security