[Patch v2 11/15] CIFS: Pass page offset for calculating signature
Tom Talpey
tom at talpey.com
Sun Jun 24 02:27:18 UTC 2018
On 5/30/2018 3:48 PM, Long Li wrote:
> From: Long Li <longli at microsoft.com>
>
> When calculating signature for the packet, it needs to read into the
> correct page offset for the data.
>
> Signed-off-by: Long Li <longli at microsoft.com>
> ---
> fs/cifs/cifsencrypt.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index a6ef088..e88303c 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -68,11 +68,12 @@ int __cifs_calc_signature(struct smb_rqst *rqst,
>
> /* now hash over the rq_pages array */
> for (i = 0; i < rqst->rq_npages; i++) {
> - void *kaddr = kmap(rqst->rq_pages[i]);
> - size_t len = rqst->rq_pagesz;
> + void *kaddr;
> + unsigned int len, offset;
>
> - if (i == rqst->rq_npages - 1)
> - len = rqst->rq_tailsz;
> + rqst_page_get_length(rqst, i, &len, &offset);
> +
> + kaddr = (char *) kmap(rqst->rq_pages[i]) + offset;
I suppose it's more robust to map a page at a time, but it's pretty
expensive. Is this the only way to iterate over a potentially very
large block of data? For example, a 1MB segment means 256 kmap/kunmaps.
Tom.
>
> crypto_shash_update(shash, kaddr, len);
>
>
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