[PATCH 3/3] Fix problems on multi-TB filesystem and file

[PATCH 3/3] Fix problems on multi-TB filesystem and file

[Takashi Sato]

This fix was proposed by Trond Myklebust.  He says:
 The type "sector_t" is heavily tied in to the block layer interface
 as an offset/handle to a block, and is subject to a supposedly
 block-specific configuration option: CONFIG_LBD. Despite this, it is
 used in struct kstatfs to save a couple of bytes on the stack
 whenever we call the filesystems' ->statfs().

So kstatfs's entries related to blocks are invalid on statfs64 for a
network filesystem which has more than 2^32-1 blocks when CONFIG_LBD
is disabled.

The content of the patch attached to this mail is below.
- struct kstatfs
  Change the type of following entries from sector_t to u64.
  f_blocks
  f_bfree
  f_bavail
  f_files
  f_ffree

Any feedback and comments are welcome.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Takashi Sato <sho@tnes.nec.co.jp>

diff -uprN -X /home/sho/blocks/linux-2.6.15-rc5-blocks/Documentation/dontdiff linux-2.6.15-rc5-blocks/include/linux/statfs.h
linux-2.6.15-rc5-kstatfs/include/linux/statfs.h
--- linux-2.6.15-rc5-blocks/include/linux/statfs.h	2005-10-28 09:02:08.000000000 +0900
+++ linux-2.6.15-rc5-kstatfs/include/linux/statfs.h	2005-12-16 18:29:51.000000000 +0900
@@ -8,11 +8,11 @@
 struct kstatfs {
 	long f_type;
 	long f_bsize;
-	sector_t f_blocks;
-	sector_t f_bfree;
-	sector_t f_bavail;
-	sector_t f_files;
-	sector_t f_ffree;
+	u64 f_blocks;
+	u64 f_bfree;
+	u64 f_bavail;
+	u64 f_files;
+	u64 f_ffree;
 	__kernel_fsid_t f_fsid;
 	long f_namelen;
 	long f_frsize;

-- Takashi Sato

Re: [PATCH 3/3] Fix problems on multi-TB filesystem and file

[Trond Myklebust]

On Sat, 2005-12-17 at 03:39 +0800, Coywolf Qi Hunt wrote:

> That CONFIG_LBD is disabled means the kernel is not capable to attach
> a large block device, whether through network or locally attached.  So
> in order to use a large network filesystem, simply enable LBD instead.
>  Don't bother to bring unnecessary overheads.

It may surprise you to learn that not all network filesystems are block
based.

NFS has no truck with CONFIG_LBD at all.

Cheers,
  Trond

Re: [PATCH 3/3] Fix problems on multi-TB filesystem and file

[Trond Myklebust]

On Sat, 2005-12-17 at 04:24 +0800, Coywolf Qi Hunt wrote:

> >
> > It may surprise you to learn that not all network filesystems are block
> > based.
> >
> > NFS has no truck with CONFIG_LBD at all.
> 
> I thought no network filesystems are block based from a client
> viewpoint.  (There's a network block driver though.) Client kernel
> needn't enable LBD.

Without this patch, the client _would_ have to enable LBD if it wanted
to correctly report the size of a large disk on the remote server.

The main point, though is that sector_t is a handle to a block. It is
_NOT_ the right type to use for reporting a disk size.

Cheers,
  Trond

[PATCH 3/3] Fix problems on multi-TB filesystem and file

[Takashi Sato]

This fix was proposed by Trond Myklebust.  He says:
 The type "sector_t" is heavily tied in to the block layer interface
 as an offset/handle to a block, and is subject to a supposedly
 block-specific configuration option: CONFIG_LBD. Despite this, it is
 used in struct kstatfs to save a couple of bytes on the stack
 whenever we call the filesystems' ->statfs().

So kstatfs's entries related to blocks are invalid on statfs64 for a
network filesystem which has more than 2^32-1 blocks when CONFIG_LBD
is disabled.

The content of the patch attached to this mail is below.
- struct kstatfs
  Change the type of following entries from sector_t to u64.
  f_blocks
  f_bfree
  f_bavail
  f_files
  f_ffree

Any feedback and comments are welcome.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Takashi Sato <sho@tnes.nec.co.jp>

diff -uprN -X linux-2.6.15-lsf/Documentation/dontdiff linux-2.6.15-lsf/include/linux/statfs.h
linux-2.6.15-kstatfs/include/linux/statfs.h
--- linux-2.6.15-lsf/include/linux/statfs.h	2006-01-03 12:21:10.000000000 +0900
+++ linux-2.6.15-kstatfs/include/linux/statfs.h	2006-01-04 15:24:38.000000000 +0900
@@ -8,11 +8,11 @@
 struct kstatfs {
 	long f_type;
 	long f_bsize;
-	sector_t f_blocks;
-	sector_t f_bfree;
-	sector_t f_bavail;
-	sector_t f_files;
-	sector_t f_ffree;
+	u64 f_blocks;
+	u64 f_bfree;
+	u64 f_bavail;
+	u64 f_files;
+	u64 f_ffree;
 	__kernel_fsid_t f_fsid;
 	long f_namelen;
 	long f_frsize;

-- Takashi Sato

Re: [PATCH 3/3] Fix problems on multi-TB filesystem and file

[Andrew Morton]

"Takashi Sato" <sho@tnes.nec.co.jp> wrote:
>
> his fix was proposed by Trond Myklebust.  He says:
>   The type "sector_t" is heavily tied in to the block layer interface
>   as an offset/handle to a block, and is subject to a supposedly
>   block-specific configuration option: CONFIG_LBD. Despite this, it is
>   used in struct kstatfs to save a couple of bytes on the stack
>   whenever we call the filesystems' ->statfs().
> 
>  So kstatfs's entries related to blocks are invalid on statfs64 for a
>  network filesystem which has more than 2^32-1 blocks when CONFIG_LBD
>  is disabled.
> 

That makes sense, thanks.