How to make VFAT work right in 2.4.0-prerelease

How to make VFAT work right in 2.4.0-prerelease

[Ivan Baldo]

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	Hello.
HOWTO:
	- edit file fs/fat/inode.c, look in the function named
"fat_notify_change" (at about line 901), where it says:"
	/* FAT cannot truncate to a longer file */
	if (attr->ia_valid & ATTR_SIZE) {
		if (attr->ia_size > inode->i_size)
			return -EPERM;
	}
	", just delete all of it (or comment it out). This change wich has been
made in the -prerelease versión, makes Netscape Messenger not to work
with email stored on a VFAT partition, ok, I guess that maybe is
Netscape's fault though, but just removing that code makes Messenger at
least work somewhat.
	- apply attached patch made by Eelco Dolstra
<edolstra@students.cs.uu.nl>, I am testing and using this patch since
13.nov.2000 (a lot of time) and with various versions of the Linux
2.4.0-testXX series kernels and it works flawlessly! Without it you get
allocation errors when using the "truncate()" C function to grow files
(and Messenger seems to use it).
	- recompile the kernel and be happy!

	I don't know why this patch isn't applied yet on the official kernel
and why the kernel people made that change to the inode.c file, maybe
they could explain us (please!).

	Thanks a lot to everyone and special thanks to Eelco!
	Goodbye.

P.s.: yes, I am writing this email with Netscape Messenger with emails
stored on a VFAT partition and using the 2.4.0-prerelease kernel with
those changes: no problems so far.
-- 
Ivan Baldo:
lubaldo@adinet.com.uy - http://go.to/ibaldo - ICQ 10215364
Phone: (598) (2) 613 3223.
Caldas 1781, 11400 Malvin, Montevideo, Uruguay, South America.

(If you have problems with the previous addresses, try this ones:
ibaldo@usa.net, http://members.xoom.com/baldo.1).

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Re: How to make VFAT work right in 2.4.0-prereleaseu

[Alan Cox]

> 	- edit file fs/fat/inode.c, look in the function named
> "fat_notify_change" (at about line 901), where it says:"
> 	/* FAT cannot truncate to a longer file */
> 	if (attr->ia_valid & ATTR_SIZE) {
> 		if (attr->ia_size > inode->i_size)
> 			return -EPERM;
> 	}
> 	", just delete all of it (or comment it out). This change wich has been
> made in the -prerelease versión, makes Netscape Messenger not to work

If you do that you will corrupt your FAT fs. Very bad idea

> 	- apply attached patch made by Eelco Dolstra
> <edolstra@students.cs.uu.nl>, I am testing and using this patch since
> 13.nov.2000 (a lot of time) and with various versions of the Linux
> 2.4.0-testXX series kernels and it works flawlessly! Without it you get

2.4.0-ac has the truncate to grow stuff. It should just work out of the box.
Let me know if not


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Re: How to make VFAT work right in 2.4.0-prereleaseu

[Eelco Dolstra]

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Hi,

On Sat, 6 Jan 2001, Alan Cox wrote:

> > 	- edit file fs/fat/inode.c, look in the function named
> > "fat_notify_change" (at about line 901), where it says:"
> > 	/* FAT cannot truncate to a longer file */
> > 	if (attr->ia_valid & ATTR_SIZE) {
> > 		if (attr->ia_size > inode->i_size)
> > 			return -EPERM;
> > 	}
> > 	", just delete all of it (or comment it out). This change wich has been
> > made in the -prerelease versión, makes Netscape Messenger not to work
> 
> If you do that you will corrupt your FAT fs.

But only on SMP, right?  The only other FAT change I see in -ac (apart
from my patch) is the spinlock around fat_cache.

Regards,

Eelco.




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Re: How to make VFAT work right in 2.4.0-prereleaseu

[Alan Cox]

> > > =09", just delete all of it (or comment it out). This change wich has b=
> een
> > > made in the -prerelease versi=F3n, makes Netscape Messenger not to work
> >=20
> > If you do that you will corrupt your FAT fs.
> 
> But only on SMP, right?  The only other FAT change I see in -ac (apart
> from my patch) is the spinlock around fat_cache.

SMP and uniprocessor will both corrupt the fatfs sometimes if you ftruncate
files larger without the grow the file patch.

Returning 0 not -EPERM also seems to be a valid standards compliant behaviour

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