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author | Chuck Lever <chuck.lever@oracle.com> | 2017-06-30 19:03:54 +0300 |
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committer | J. Bruce Fields <bfields@redhat.com> | 2017-07-12 22:54:55 +0300 |
commit | 8c6ae4980e70395cbdfdf605c29673c5a6a89d9a (patch) | |
tree | c334332505b52c05aeb441a83c0b384ebcfccea9 /include/linux/sunrpc/svc.h | |
parent | 2d6491a56c76f2d6c22aaa710e2a4d04ad41529b (diff) | |
download | linux-8c6ae4980e70395cbdfdf605c29673c5a6a89d9a.tar.xz |
sunrpc: Allocate up to RPCSVC_MAXPAGES per svc_rqst
svcrdma needs 259 pages allocated to receive 1MB NFSv4.0 WRITE requests:
- 1 page for the transport header and head iovec
- 256 pages for the data payload
- 1 page for the trailing GETATTR request (since NFSD XDR decoding
does not look for a tail iovec, the GETATTR is stuck at the end
of the rqstp->rq_arg.pages list)
- 1 page for building the reply xdr_buf
But RPCSVC_MAXPAGES is already 259 (on x86_64). The problem is that
svc_alloc_arg never allocates that many pages. To address this:
1. The final element of rq_pages always points to NULL. To
accommodate up to 259 pages in rq_pages, add an extra element
to rq_pages for the array termination sentinel.
2. Adjust the calculation of "pages" to match how RPCSVC_MAXPAGES
is calculated, so it can go up to 259. Bruce noted that the
calculation assumes sv_max_mesg is a multiple of PAGE_SIZE,
which might not always be true. I didn't change this assumption.
3. Change the loop boundaries to allow 259 pages to be allocated.
Additional clean-up: WARN_ON_ONCE adds an extra conditional branch,
which is basically never taken. And there's no need to dump the
stack here because svc_alloc_arg has only one caller.
Keeping that NULL "array termination sentinel"; there doesn't appear to
be any code that depends on it, only code in nfsd_splice_actor() which
needs the 259th element to be initialized to *something*. So it's
possible we could just keep the array at 259 elements and drop that
final NULL, but we're being conservative for now.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'include/linux/sunrpc/svc.h')
-rw-r--r-- | include/linux/sunrpc/svc.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index eec04982a7ea..a3f8af9bd543 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -246,7 +246,7 @@ struct svc_rqst { size_t rq_xprt_hlen; /* xprt header len */ struct xdr_buf rq_arg; struct xdr_buf rq_res; - struct page * rq_pages[RPCSVC_MAXPAGES]; + struct page *rq_pages[RPCSVC_MAXPAGES + 1]; struct page * *rq_respages; /* points into rq_pages */ struct page * *rq_next_page; /* next reply page to use */ struct page * *rq_page_end; /* one past the last page */ |