[PATCH] V7: Add support for non-PDP11 v7 filesystems

[PATCH] V7: Add support for non-PDP11 v7 filesystems

[Lubomir Rintel]

A mount-time option was added that makes it possible to override the
endianness and an attempt is made to autodetect it (which seems easy,
given the disk addresses are 3-byte.

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
@@ -24,6 +24,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/buffer_head.h>
+#include <linux/parser.h>
 #include "sysv.h"
 
 /*
@@ -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;
+	}
+
+	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))) {
+		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);
 	brelse(bh);
 	kfree(sbi);
 	return -EINVAL;
-- 
1.7.2

Re: [PATCH] V7: Add support for non-PDP11 v7 filesystems

[Lubomir Rintel]

On Mon, 2010-07-26 at 00:50 +0200, Lubomir Rintel wrote:
> A mount-time option was added that makes it possible to override the
> endianness and an attempt is made to autodetect it (which seems easy,
> given the disk addresses are 3-byte.
> 
> No attempt is made to detect big-endian filesystems -- were there any?
> Tested with PDP-11 v7 filesystems and PC-IX maintenance floppy.

This should have been a reply to
<20100724135128.GA11645@ZenIV.linux.org.uk>
Moreover it has a bad commit message; By bad, please ignore this one.

sorry
-- 
Flash is the Web2.0 version of blink and animated gifs.
                                     -- Stephen Smoogen

Re: [PATCH 3/3] [fs/sysv] V7: Add support for non-PDP11 v7 filesystems

[Al Viro]

On Mon, Jul 19, 2010 at 04:58:51PM +0200, Christoph Hellwig wrote:
> On Mon, Jul 19, 2010 at 07:16:42PM +0200, Lubomir Rintel wrote:
> > A mount-time option was added that makes it possible to override the
> > endianness and an attempt is made to autodetect it (which seems easy,
> > given the disk addresses are 3-byte.
> > 
> > No attempt is made to detect big-endian filesystems -- were there any?
> > Tested with PDP-11 v7 filesystems and PC-IX maintenance floppy.
> 
> Do you actually need the mount option?  We get away just fine with
> it for sysv filesystems.  And if not I'd be consistent and accept the
> options for both sysv and v7 filesystems.

Actually, it shouldn't be too hard to detect the damn thing even without magic.
Look - we always have the inode table starting at block 2, so on-disk root
inode is guaranteed to be found correctly.  Now, suppose we'd mistaken
l-e for pdp or vice versa; the half-words of i_size would get swapped.
What could pass both tests?  Suppose the right size is a * 65536 + b;
then we have: a and b are both multiples of 16 and at least one is non-zero.
So all we need is to reject root directories bigger than 1Mb.  And posted
patches do reject that (and lower than that, actually).

So I'd rather see a variant without that option.  Simply get both bh, then
try the same sanity checks with LE and PDP used for s_bytesex.  And use
one that works - we _know_ that it's impossible to have both pass at the
same time.

I'm fine with the rest of patch series as is; Lubomir, could you redo the
last one that way and resend?

[PATCH] V7: Add support for non-PDP11 v7 filesystems

[Lubomir Rintel]

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
@@ -24,6 +24,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/buffer_head.h>
+#include <linux/parser.h>
 #include "sysv.h"
 
 /*
@@ -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;
+	}
+
+	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))) {
+		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);
 	brelse(bh);
 	kfree(sbi);
 	return -EINVAL;
-- 
1.7.2

Re: [PATCH] V7: Add support for non-PDP11 v7 filesystems

[Randy Dunlap]

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 ***

Re: [PATCH] V7: Add support for non-PDP11 v7 filesystems

[Andrew Morton]

On Mon, 26 Jul 2010 00:59:16 +0200
Lubomir Rintel <lkundrak@v3.sk> 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.

Which kernel is this against?  My v7_fill_super() is significantly
different from yours.

Re: [PATCH] V7: Add support for non-PDP11 v7 filesystems

[Lubomir Rintel]

On Mon, 2010-07-26 at 16:52 -0700, Andrew Morton wrote:
> On Mon, 26 Jul 2010 00:59:16 +0200
> Lubomir Rintel <lkundrak@v3.sk> 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.
> 
> Which kernel is this against?  My v7_fill_super() is significantly
> different from yours.

This depends on [PATCH] V7: Adjust sanity checks for some volumes
<1279761108-302-1-git-send-email-lkundrak@v3.sk>.

It might be that I've messed up something in the communication so that
the dependency was not immediately clear. To be honest, I'm not very
familiar with the way reviews and adjustements to patches are tracked.
What have I done wrong, here? How am I supposed to follow up with a
change to a single patch of a multi-patch (be it just two in this case)
set?

-- 
Flash is the Web2.0 version of blink and animated gifs.
                                     -- Stephen Smoogen

Re: [PATCH] V7: Add support for non-PDP11 v7 filesystems

[Andrew Morton]

On Tue, 27 Jul 2010 02:19:15 +0200 Lubomir Rintel <lkundrak@v3.sk> wrote:

> On Mon, 2010-07-26 at 16:52 -0700, Andrew Morton wrote:
> > On Mon, 26 Jul 2010 00:59:16 +0200
> > Lubomir Rintel <lkundrak@v3.sk> 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.
> > 
> > Which kernel is this against?  My v7_fill_super() is significantly
> > different from yours.
> 
> This depends on [PATCH] V7: Adjust sanity checks for some volumes
> <1279761108-302-1-git-send-email-lkundrak@v3.sk>.
> 
> It might be that I've messed up something in the communication so that
> the dependency was not immediately clear. To be honest, I'm not very
> familiar with the way reviews and adjustements to patches are tracked.
> What have I done wrong, here? How am I supposed to follow up with a
> change to a single patch of a multi-patch (be it just two in this case)
> set?

ah, OK, I managed to confuse myself with
fs-sysv-v7-adjust-sanity-checks-for-some-volumes-checkpatch-fixes.patch.

This new patch triggers many warnings also:

ERROR: do not use assignment in if condition
#52: FILE: fs/sysv/super.c:456:
+	if ((bh2 = sb_bread(sb, 2)) == NULL) {

WARNING: braces {} are not necessary for single statement blocks
#52: FILE: fs/sysv/super.c:456:
+	if ((bh2 = sb_bread(sb, 2)) == NULL) {
+		return 0;
+	}

ERROR: code indent should use tabs where possible
#61: FILE: fs/sysv/super.c:465:
+             sizeof (struct sysv_dir_entry))) {$

WARNING: please, no space for starting a line, 
				excluding comments
#61: FILE: fs/sysv/super.c:465:
+             sizeof (struct sysv_dir_entry))) {$

WARNING: space prohibited between function name and open parenthesis '('
#61: FILE: fs/sysv/super.c:465:
+             sizeof (struct sysv_dir_entry))) {

WARNING: space prohibited between function name and open parenthesis '('
#97: FILE: fs/sysv/super.c:504:
+	if (v7_sanity_check (sb, bh))

WARNING: space prohibited between function name and open parenthesis '('
#115: FILE: fs/sysv/super.c:509:
+	if (v7_sanity_check (sb, bh))

WARNING: printk() should include KERN_ facility level
#128: FILE: fs/sysv/super.c:521:
+	printk("VFS: could not find a valid V7 on %s.\n", sb->s_id);

total: 2 errors, 6 warnings, 109 lines checked

./patches/v7-add-support-for-non-pdp11-v7-filesystems.patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.




--- a/fs/sysv/super.c~fs-sysv-superc-add-support-for-non-pdp11-v7-filesystems-checkpatch-fixes
+++ a/fs/sysv/super.c
@@ -453,16 +453,16 @@ static int v7_sanity_check(struct super_
 
 	/* 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) {
+	bh2 = sb_bread(sb, 2);
+	if (bh2 == NULL)
 		return 0;
-	}
 
 	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;
 	}
@@ -501,12 +501,12 @@ static int v7_fill_super(struct super_bl
 
 	/* Try PDP-11 UNIX */
 	sbi->s_bytesex = BYTESEX_PDP;
-	if (v7_sanity_check (sb, bh))
+	if (v7_sanity_check(sb, bh))
 		goto detected;
 
 	/* Try PC/IX, v7/x86 */
 	sbi->s_bytesex = BYTESEX_LE;
-	if (v7_sanity_check (sb, bh))
+	if (v7_sanity_check(sb, bh))
 		goto detected;
 
 	goto failed;
@@ -518,7 +518,8 @@ detected:
 		return 0;
 
 failed:
-	printk("VFS: could not find a valid V7 on %s.\n", sb->s_id);
+	printk(KERN_ERR "VFS: could not find a valid V7 on %s.\n",
+		sb->s_id);
 	brelse(bh);
 	kfree(sbi);
 	return -EINVAL;
_

Re: [PATCH 3/3] [fs/sysv] V7: Add support for non-PDP11 v7 filesystems

[Lubomir Rintel]

On Tue, 2010-07-20 at 12:41 +0200, Lubomir Rintel wrote:
> On Mon, 2010-07-19 at 16:58 +0200, Christoph Hellwig wrote:
... 
> > Do you actually need the mount option?  We get away just fine with
> > it for sysv filesystems.  And if not I'd be consistent and accept the
> > options for both sysv and v7 filesystems.
...
> Coherent seems to always use PDP-11 bytesex. I can not check at the
> time, but I'm almost sure it never run on such machines (was PC and 68k
> only?), so I suspect the coherent kernel might have always done the
> translation to native byte order. I think I have some coherent (for PC)
> floppies at home, so I can check tomorrow.

This was just partly correct. Coherent indeed run on PDP-11 (and not on
68k), but the PC version uses the very same bytesex as PDP-11 one,
translating the byte order on the fly (_canl() routine defined in
i386/as.inc file of Coherent 4.2.10 for i386 kernel is used).

Thus the mount option is really only useful with v7 filesystem and none
of those handled with sysv filesystem.

-- 
Flash is the Web2.0 version of blink and animated gifs.
                                     -- Stephen Smoogen

[PATCH] V7: Add support for non-PDP11 v7 filesystems

[Lubomir Rintel]

A mount-time option was added that makes it possible to override the
endianness and an attempt is made to autodetect it (which seems easy,
given the disk addresses are 3-byte.

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>
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
---
 fs/sysv/super.c |  116 +++++++++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 92 insertions(+), 24 deletions(-)

diff --git a/fs/sysv/super.c b/fs/sysv/super.c
index ac7b008..ca4e8aa 100644
--- a/fs/sysv/super.c
+++ b/fs/sysv/super.c
@@ -24,6 +24,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/buffer_head.h>
+#include <linux/parser.h>
 #include "sysv.h"
 
 /*
@@ -435,12 +436,55 @@ 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;
+	}
+
+	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))) {
+		brelse(bh2);
+		return 0;
+	}
+
+	brelse(bh2);
+	return 1;
+}
+
+enum { Opt_err, Opt_bytesex_pdp, Opt_bytesex_le, Opt_bytesex_be };
+
+static const match_table_t v7_tokens = {
+	{Opt_bytesex_pdp, "bytesex=pdp"},
+	{Opt_bytesex_le, "bytesex=le"},
+	{Opt_bytesex_be, "bytesex=be"},
+	{Opt_err, NULL}
+};
+
+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 +498,6 @@ 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 +509,59 @@ 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;
+	if (data) {
+		substring_t args[MAX_OPT_ARGS];
+		char *p;
+
+		while ((p = strsep ((char **)&data, ",")) != NULL) {
+			int token;
+			if (!*p)
+				continue;
+			token = match_token(p, v7_tokens, args);
+			switch (token) {
+			case Opt_bytesex_pdp:
+				sbi->s_bytesex = BYTESEX_PDP;
+				break;
+			case Opt_bytesex_le:
+				sbi->s_bytesex = BYTESEX_LE;
+				break;
+			case Opt_bytesex_be:
+				sbi->s_bytesex = BYTESEX_BE;
+				break;
+			default:
+				/* An unrecognized option */
+				goto failed;
+			}
+		}
+	}
 
-	/* 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;
+	/* Endianness overridden by a mount option */
+	if (sbi->s_bytesex) {
+		if (!v7_sanity_check (sb, bh))
+			goto failed;
+		goto detected;
+	}
+
+	/* Try PDP-11 UNIX */
+	sbi->s_bytesex = BYTESEX_PDP;
+	if (v7_sanity_check (sb, bh))
+		goto detected;
+
+	/* 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);
 	brelse(bh);
 	kfree(sbi);
 	return -EINVAL;
-- 
1.7.1