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SubjectRe: [PATCH] V7: Add support for non-PDP11 v7 filesystems
On Mon, 26 Jul 2010 00:59:16 +0200 Lubomir Rintel wrote:

> This adds byte order autodetection (of PDP-11 and LE filesystems).
> No attempt is made to detect big-endian filesystems -- were there any?
> Tested with PDP-11 v7 filesystems and PC-IX maintenance floppy.
>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Al Viro <viro@ZenIV.linux.org.uk>
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> ---
> fs/sysv/super.c | 74 +++++++++++++++++++++++++++++++++++++------------------
> 1 files changed, 50 insertions(+), 24 deletions(-)
>
> diff --git a/fs/sysv/super.c b/fs/sysv/super.c
> index ac7b008..0433f23 100644
> --- a/fs/sysv/super.c
> +++ b/fs/sysv/super.c
> @@ -435,12 +436,46 @@ Ebadsize:
> goto failed;
> }
>
> -static int v7_fill_super(struct super_block *sb, void *data, int silent)
> +static int v7_sanity_check(struct super_block *sb, struct buffer_head *bh)
> {
> - struct sysv_sb_info *sbi;
> - struct buffer_head *bh, *bh2 = NULL;
> struct v7_super_block *v7sb;
> struct sysv_inode *v7i;
> + struct buffer_head *bh2;
> + struct sysv_sb_info *sbi;
> +
> + sbi = sb->s_fs_info;
> +
> + /* plausibility check on superblock */
> + v7sb = (struct v7_super_block *) bh->b_data;
> + if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
> + fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
> + fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE)
> + return 0;
> +
> + /* plausibility check on root inode: it is a directory,
> + with a nonzero size that is a multiple of 16 */
> + if ((bh2 = sb_bread(sb, 2)) == NULL) {
> + return 0;
> + }

Don't need the braces.

> +
> + v7i = (struct sysv_inode *)(bh2->b_data + 64);
> + if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
> + (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
> + (fs32_to_cpu(sbi, v7i->i_size) & 017) ||
> + (fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES *
> + sizeof (struct sysv_dir_entry))) {

sizeof(struct sysv_dir_entry))) {

> + brelse(bh2);
> + return 0;
> + }
> +
> + brelse(bh2);
> + return 1;
> +}
> +
> +static int v7_fill_super(struct super_block *sb, void *data, int silent)
> +{
> + struct sysv_sb_info *sbi;
> + struct buffer_head *bh;
>
> if (440 != sizeof (struct v7_super_block))
> panic("V7 FS: bad super-block size");
> @@ -454,7 +489,6 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
> sbi->s_sb = sb;
> sbi->s_block_base = 0;
> sbi->s_type = FSTYPE_V7;
> - sbi->s_bytesex = BYTESEX_PDP;
> sb->s_fs_info = sbi;
>
> sb_set_blocksize(sb, 512);
> @@ -466,34 +500,26 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
> goto failed;
> }
>
> - /* plausibility check on superblock */
> - v7sb = (struct v7_super_block *) bh->b_data;
> - if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
> - fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
> - fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE)
> - goto failed;
> + /* Try PDP-11 UNIX */
> + sbi->s_bytesex = BYTESEX_PDP;
> + if (v7_sanity_check (sb, bh))
> + goto detected;
>
> - /* plausibility check on root inode: it is a directory,
> - with a nonzero size that is a multiple of 16 */
> - if ((bh2 = sb_bread(sb, 2)) == NULL)
> - goto failed;
> - v7i = (struct sysv_inode *)(bh2->b_data + 64);
> - if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
> - (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
> - (fs32_to_cpu(sbi, v7i->i_size) & 017) ||
> - (fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES *
> - sizeof (struct sysv_dir_entry)))
> - goto failed;
> - brelse(bh2);
> - bh2 = NULL;
> + /* Try PC/IX, v7/x86 */
> + sbi->s_bytesex = BYTESEX_LE;
> + if (v7_sanity_check (sb, bh))
> + goto detected;
>
> + goto failed;
> +
> +detected:
> sbi->s_bh1 = bh;
> sbi->s_bh2 = bh;
> if (complete_read_super(sb, silent, 1))
> return 0;
>
> failed:
> - brelse(bh2);
> + printk("VFS: could not find a valid V7 on %s.\n", sb->s_id);

V7 fs (or V7 filesystem)

> brelse(bh);
> kfree(sbi);
> return -EINVAL;
> --


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***


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