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nfsd41: check encode size for sessions maxresponse cached

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Calculate the space the compound response has taken after encoding the current
operation.

pad: add on 8 bytes for the next operation's op_code and status so that
there is room to cache a failure on the next operation.

Compare this length to the session se_fmaxresp_cached and return
nfserr_rep_too_big_to_cache if the length is too large.

Our se_fmaxresp_cached will always be a multiple of PAGE_SIZE, and so
will be at least a page and will therefore hold the xdr_buf head.

Signed-off-by: Andy Adamson <andros@netapp.com>
[nfsd41: non-page DRC for solo sequence responses]
[fixed nfsd4_check_drc_limit cosmetics]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41: use cstate session in nfsd4_check_drc_limit]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
Andy Adamson 2009-04-03 08:28:48 +03:00 committed by J. Bruce Fields
parent 6668958fac
commit 496c262cf0
1 changed files with 51 additions and 0 deletions
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51
fs/nfsd/nfs4xdr.c
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@ -3078,6 +3078,54 @@ static nfsd4_enc nfsd4_enc_ops[] = {
[OP_RECLAIM_COMPLETE] = (nfsd4_enc)nfsd4_encode_noop,
};
/*
* Calculate the total amount of memory that the compound response has taken
* after encoding the current operation.
*
* pad: add on 8 bytes for the next operation's op_code and status so that
* there is room to cache a failure on the next operation.
*
* Compare this length to the session se_fmaxresp_cached.
*
* Our se_fmaxresp_cached will always be a multiple of PAGE_SIZE, and so
* will be at least a page and will therefore hold the xdr_buf head.
*/
static int nfsd4_check_drc_limit(struct nfsd4_compoundres *resp)
{
int status = 0;
struct xdr_buf *xb = &resp->rqstp->rq_res;
struct nfsd4_compoundargs *args = resp->rqstp->rq_argp;
struct nfsd4_session *session = NULL;
struct nfsd4_slot *slot = resp->cstate.slot;
u32 length, tlen = 0, pad = 8;
if (!nfsd4_has_session(&resp->cstate))
return status;
session = resp->cstate.session;
if (session == NULL || slot->sl_cache_entry.ce_cachethis == 0)
return status;
if (resp->opcnt >= args->opcnt)
pad = 0; /* this is the last operation */
if (xb->page_len == 0) {
length = (char *)resp->p - (char *)xb->head[0].iov_base + pad;
} else {
if (xb->tail[0].iov_base && xb->tail[0].iov_len > 0)
tlen = (char *)resp->p - (char *)xb->tail[0].iov_base;
length = xb->head[0].iov_len + xb->page_len + tlen + pad;
}
dprintk("%s length %u, xb->page_len %u tlen %u pad %u\n", __func__,
length, xb->page_len, tlen, pad);
if (length <= session->se_fmaxresp_cached)
return status;
else
return nfserr_rep_too_big_to_cache;
}
void
nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
{
@ -3094,6 +3142,9 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
BUG_ON(op->opnum < 0 || op->opnum >= ARRAY_SIZE(nfsd4_enc_ops) ||
!nfsd4_enc_ops[op->opnum]);
op->status = nfsd4_enc_ops[op->opnum](resp, op->status, &op->u);
/* nfsd4_check_drc_limit guarantees enough room for error status */
if (!op->status && nfsd4_check_drc_limit(resp))
op->status = nfserr_rep_too_big_to_cache;
status:
/*
* Note: We write the status directly, instead of using WRITE32(),