On Thu, 17 Feb 2011 14:12:41 -0800, "Venkateswararao Jujjuri (JV)" <jvrao@xxxxxxxxxxxxxxxxxx> wrote:
> If a transport prefers payload to be sent separate from the PDU
> (P9_TRANS_PREF_PAYLOAD_SEP), there is no need to allocate msize
> PDU buffers(struct p9_fcall).
>
> This patch allocates only upto 4k buffers for this kind of transports
> and there won't be any change to the legacy transports.
>
> Hence, this patch on top of zero copy changes allows user to
> specify higher msizes through the mount option
> without hogging the kernel heap.
>
> Signed-off-by: Venkateswararao Jujjuri <jvrao@xxxxxxxxxxxxxxxxxx>
> ---
> include/net/9p/9p.h | 2 +-
> net/9p/client.c | 23 +++++++++++++++++------
> 2 files changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
> index 7aefa6d..eaa45f9 100644
> --- a/include/net/9p/9p.h
> +++ b/include/net/9p/9p.h
> @@ -688,7 +688,7 @@ struct p9_rwstat {
> * @id: protocol operating identifier of type &p9_msg_t
> * @tag: transaction id of the request
> * @offset: used by marshalling routines to track currentposition in buffer
> - * @capacity: used by marshalling routines to track total capacity
> + * @capacity: used by marshalling routines to track total malloc'd capacity
> * @pubuf: Payload user buffer given by the caller
> * @pubuf: Payload kernel buffer given by the caller
> * @pbuf_size: pubuf/pkbuf(only one will be !NULL) size to be read/write.
> diff --git a/net/9p/client.c b/net/9p/client.c
> index 251abb1..43ec78a 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -229,10 +229,23 @@ static struct p9_req_t *p9_tag_alloc(struct p9_client *c, u16 tag)
> return ERR_PTR(-ENOMEM);
> }
> init_waitqueue_head(req->wq);
> - req->tc = kmalloc(sizeof(struct p9_fcall)+c->msize,
> - GFP_KERNEL);
> - req->rc = kmalloc(sizeof(struct p9_fcall)+c->msize,
> - GFP_KERNEL);
> + if ((c->trans_mod->pref & P9_TRANS_PREF_PAYLOAD_MASK) ==
> + P9_TRANS_PREF_PAYLOAD_SEP) {
> + int alloc_msize = min(c->msize, 4096);
value 4096 should be a #define with a comment explaining how we arrived
at value 4096
> + req->tc = kmalloc(sizeof(struct p9_fcall)+alloc_msize,
> + GFP_KERNEL);
> + req->tc->capacity = alloc_msize;
> + req->rc = kmalloc(sizeof(struct p9_fcall)+alloc_msize,
> + GFP_KERNEL);
> + req->rc->capacity = alloc_msize;
> + } else {
> + req->tc = kmalloc(sizeof(struct p9_fcall)+c->msize,
> + GFP_KERNEL);
> + req->tc->capacity = c->msize;
> + req->rc = kmalloc(sizeof(struct p9_fcall)+c->msize,
> + GFP_KERNEL);
> + req->rc->capacity = c->msize;
> + }
> if ((!req->tc) || (!req->rc)) {
> printk(KERN_ERR "Couldn't grow tag array\n");
> kfree(req->tc);
> @@ -243,9 +256,7 @@ static struct p9_req_t *p9_tag_alloc(struct p9_client *c, u16 tag)
> return ERR_PTR(-ENOMEM);
> }
> req->tc->sdata = (char *) req->tc + sizeof(struct p9_fcall);
> - req->tc->capacity = c->msize;
> req->rc->sdata = (char *) req->rc + sizeof(struct p9_fcall);
> - req->rc->capacity = c->msize;
> }
>
> p9pdu_reset(req->tc);
-aneesh
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