On May 28, 2008 11:02 +0200, Nick Piggin wrote:
> fs: check for statfs overflow
>
> Adds a check for an overflow in the filesystem size so if someone is
> checking with statfs() on a 16G hugetlbfs in a 32bit binary that it
> will report back EOVERFLOW instead of a size of 0.
>
> Are other places that need a similar check? I had tried a similar
> check in put_compat_statfs64 too but it didn't seem to generate an
> EOVERFLOW in my test case.
>
> Signed-off-by: Jon Tollefson <kniht@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
> ---
>
> fs/compat.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>
> Index: linux-2.6/fs/compat.c
> ===================================================================
> --- linux-2.6.orig/fs/compat.c
> +++ linux-2.6/fs/compat.c
> @@ -197,8 +197,8 @@ static int put_compat_statfs(struct comp
> {
>
> if (sizeof ubuf->f_blocks == 4) {
> - if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail) &
> - 0xffffffff00000000ULL)
> + if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
> + kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
> return -EOVERFLOW;
Hmm, doesn't this check break every filesystem > 16TB on 4kB PAGE_SIZE
nodes? It would be better, IMHO, to scale down f_blocks, f_bfree, and
f_bavail and correspondingly scale up f_bsize to fit into the 32-bit
statfs structure.
We did this for several years with Lustre, as the first installation was
already larger than 16TB on 32-bit clients at the time. There was never
a problem with statfs returning a larger f_bsize, since applications
generally use the fstat() st_blocksize to determine IO size and not the
statfs() data.
Returning statfs data accurate to within a few kB is better than failing
the request outright, IMHO.
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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