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Date: Wed, 7 May 2008 08:48:39 +0900
From: "Kyungmin Park" <kmpark@infradead.org>
To: "Artem Bityutskiy" <Artem.Bityutskiy@nokia.com>
Subject: Re: [PATCH take 2 08/28] UBIFS: add superblock and master node
Cc: LKML <linux-kernel@vger.kernel.org>,
       "Adrian Hunter" <ext-adrian.hunter@nokia.com>
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Hi Artem,

Here's one proposal. Please add the  no compressed mode support.
In my simple test. it's working with  no compress mode.
Yes I know, it makes the performance poor. but we can measure the
metadata operation overhead compare to the previous flash filesystems.

How do you think?

Thank you,
Kyungmin Park


>  diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
>  new file mode 100644
>  index 0000000..2fe4c7c
>  --- /dev/null
>  +++ b/fs/ubifs/sb.c

>  +/* The default maximum size of reserved pool in bytes */
>  +#define DEFAULT_MAX_RP_SIZE (5*1024*1024)
>  +
>  +/* Default UBIFS compressor */
>  +#define DEFAULT_COMPRESSOR UBIFS_COMPR_LZO
>  +

#ifdef CONFIG_UBIFS_FS_NO_COMPR
#define DEFAULT_COMPRESSOR UBIFS_COMPR_NONE
#else
#define DEFAULT_COMPRESSOR UBIFS_COMPR_LZO
#endif


>  +       ino->mtime_nsec  = 0;
>  +       ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
>  +       ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
>  +
>  +       /* Set compression enabled by default */
>  +       ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
>  +
>  +       err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
>  +                              main_first + DEFAULT_DATA_LEB, 0,
>  +                              UBI_UNKNOWN);

#ifdef CONFIG_UBIFS_FS_NO_COMPR
       /* Don't use the compression */
       ino->flags = 0;
#else
       /* Set compression enabled by default */
       ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
#endif

Of course it also adds the UBIFS_FS_NO_COMPR to fs/ubifs/Kconfig properly.