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nfsd4: size-checking cleanup

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Better variable name, some comments, etc.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields
2014-03-11 17:54:34 -04:00
parent ea8d7720b2
commit a8095f7e80
2 changed files with 21 additions and 17 deletions
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29
fs/nfsd/nfs4xdr.c
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@@ -3739,35 +3739,36 @@ static nfsd4_enc nfsd4_enc_ops[] = {
};
/*
* Calculate the total amount of memory that the compound response has taken
* after encoding the current operation with pad.
* Calculate whether we still have space to encode repsize bytes.
* There are two considerations:
* - For NFS versions >=4.1, the size of the reply must stay within
* session limits
* - For all NFS versions, we must stay within limited preallocated
* buffer space.
*
* pad: if operation is non-idempotent, pad was calculate by op_rsize_bop()
* which was specified at nfsd4_operation, else pad is zero.
*
* Compare this length to the session se_fmaxresp_sz and 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.
* This is called before the operation is processed, so can only provide
* an upper estimate. For some nonidempotent operations (such as
* getattr), it's not necessarily a problem if that estimate is wrong,
* as we can fail it after processing without significant side effects.
*/
__be32 nfsd4_check_resp_size(struct nfsd4_compoundres *resp, u32 pad)
__be32 nfsd4_check_resp_size(struct nfsd4_compoundres *resp, u32 respsize)
{
struct xdr_buf *buf = &resp->rqstp->rq_res;
struct nfsd4_session *session = resp->cstate.session;
struct nfsd4_slot *slot = resp->cstate.slot;
int slack_bytes = (char *)resp->xdr.end - (char *)resp->xdr.p;
if (nfsd4_has_session(&resp->cstate)) {
struct nfsd4_slot *slot = resp->cstate.slot;
if (buf->len + pad > session->se_fchannel.maxresp_sz)
if (buf->len + respsize > session->se_fchannel.maxresp_sz)
return nfserr_rep_too_big;
if ((slot->sl_flags & NFSD4_SLOT_CACHETHIS) &&
buf->len + pad > session->se_fchannel.maxresp_cached)
buf->len + respsize > session->se_fchannel.maxresp_cached)
return nfserr_rep_too_big_to_cache;
}
if (pad > slack_bytes) {
if (respsize > slack_bytes) {
WARN_ON_ONCE(nfsd4_has_session(&resp->cstate));
return nfserr_resource;
}