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authorChuck Lever <chuck.lever@oracle.com>2017-06-30 12:03:54 -0400
committerJ. Bruce Fields <bfields@redhat.com>2017-07-12 15:54:55 -0400
commit8c6ae4980e70395cbdfdf605c29673c5a6a89d9a (patch)
treec334332505b52c05aeb441a83c0b384ebcfccea9 /net
parent2d6491a56c76f2d6c22aaa710e2a4d04ad41529b (diff)
downloadlinux-8c6ae4980e70395cbdfdf605c29673c5a6a89d9a.tar.bz2
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 'net')
-rw-r--r--net/sunrpc/svc_xprt.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 7bfe1fb42add..d16a8b423c20 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -659,11 +659,13 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
int i;
/* now allocate needed pages. If we get a failure, sleep briefly */
- pages = (serv->sv_max_mesg + PAGE_SIZE) / PAGE_SIZE;
- WARN_ON_ONCE(pages >= RPCSVC_MAXPAGES);
- if (pages >= RPCSVC_MAXPAGES)
+ pages = (serv->sv_max_mesg + 2 * PAGE_SIZE) >> PAGE_SHIFT;
+ if (pages > RPCSVC_MAXPAGES) {
+ pr_warn_once("svc: warning: pages=%u > RPCSVC_MAXPAGES=%lu\n",
+ pages, RPCSVC_MAXPAGES);
/* use as many pages as possible */
- pages = RPCSVC_MAXPAGES - 1;
+ pages = RPCSVC_MAXPAGES;
+ }
for (i = 0; i < pages ; i++)
while (rqstp->rq_pages[i] == NULL) {
struct page *p = alloc_page(GFP_KERNEL);