2004-06-15 05:55:20

by Chris Wedgwood

Subject: [PATCH] stat nlink resolution fix

(As already discussed)

Linus,

Some filesystems can get overflows when their link-count exceeds
65534. This patch increases the kernels internal resolution for this
and also has a check for the old-system call paths to return and error
(-EOVERFLOW) as required (as suggested by Al Viro).

Signed-off-by: Chris Wedgwood <[email protected]>

diff -Nru a/fs/stat.c b/fs/stat.c
--- a/fs/stat.c 2004-06-14 17:40:21 -07:00
+++ b/fs/stat.c 2004-06-14 17:40:21 -07:00
@@ -131,6 +131,8 @@
tmp.st_ino = stat->ino;
tmp.st_mode = stat->mode;
tmp.st_nlink = stat->nlink;
+ if (tmp.st_nlink != stat->nlink)
+ return -EOVERFLOW;
SET_UID(tmp.st_uid, stat->uid);
SET_GID(tmp.st_gid, stat->gid);
tmp.st_rdev = old_encode_dev(stat->rdev);
@@ -199,6 +201,8 @@
tmp.st_ino = stat->ino;
tmp.st_mode = stat->mode;
tmp.st_nlink = stat->nlink;
+ if (tmp.st_nlink != stat->nlink)
+ return -EOVERFLOW;
SET_UID(tmp.st_uid, stat->uid);
SET_GID(tmp.st_gid, stat->gid);
#if BITS_PER_LONG == 32
diff -Nru a/include/linux/stat.h b/include/linux/stat.h
--- a/include/linux/stat.h 2004-06-14 17:40:21 -07:00
+++ b/include/linux/stat.h 2004-06-14 17:40:21 -07:00
@@ -60,7 +60,7 @@
unsigned long ino;
dev_t dev;
umode_t mode;
- nlink_t nlink;
+ unsigned int nlink;
uid_t uid;
gid_t gid;
dev_t rdev;

2004-06-15 14:56:59

by Jörn Engel

Subject: Re: [PATCH] stat nlink resolution fix

On Mon, 14 June 2004 22:55:07 -0700, Chris Wedgwood wrote:
>
> Some filesystems can get overflows when their link-count exceeds
> 65534. This patch increases the kernels internal resolution for this
> and also has a check for the old-system call paths to return and error
> (-EOVERFLOW) as required (as suggested by Al Viro).
>
> Signed-off-by: Chris Wedgwood <[email protected]>
>
> diff -Nru a/include/linux/stat.h b/include/linux/stat.h
> --- a/include/linux/stat.h 2004-06-14 17:40:21 -07:00
> +++ b/include/linux/stat.h 2004-06-14 17:40:21 -07:00
> @@ -60,7 +60,7 @@
> unsigned long ino;
> dev_t dev;
> umode_t mode;
> - nlink_t nlink;
> + unsigned int nlink;
> uid_t uid;
> gid_t gid;
> dev_t rdev;

Just for me to get a clue, what would break if the definition of
nlink_t changed?

J?rn

--
Fancy algorithms are buggier than simple ones, and they're much harder
to implement. Use simple algorithms as well as simple data structures.
-- Rob Pike

2004-06-15 18:22:29

by Chris Wedgwood

Subject: Re: [PATCH] stat nlink resolution fix

On Tue, Jun 15, 2004 at 04:56:25PM +0200, J?rn Engel wrote:

> Just for me to get a clue, what would break if the definition of
> nlink_t changed?

It's derived from __kernel_nlink_t which is exported to userspace
(well, glibc headers).


--cw