pNFS: Don't allocate more pages than we need to fit a layoutget response

For the 'files' and 'flexfiles' layout types, we do not expect the reply
to be any larger than 4k. The block and scsi layout types are a little more
greedy, so we keep allocating the maximum response size for now.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 6b5b2d36f502..c5672c02afd6 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -991,6 +991,7 @@ pnfs_alloc_init_layoutget_args(struct inode *ino,
 	   gfp_t gfp_flags)
 {
 	struct nfs_server *server = pnfs_find_server(ino, ctx);
+	size_t max_reply_sz = server->pnfs_curr_ld->max_layoutget_response;
 	size_t max_pages = max_response_pages(server);
 	struct nfs4_layoutget *lgp;
 
@@ -1000,6 +1001,12 @@ pnfs_alloc_init_layoutget_args(struct inode *ino,
 	if (lgp == NULL)
 		return NULL;
 
+	if (max_reply_sz) {
+		size_t npages = (max_reply_sz + PAGE_SIZE - 1) >> PAGE_SHIFT;
+		if (npages < max_pages)
+			max_pages = npages;
+	}
+
 	lgp->args.layout.pages = nfs4_alloc_pages(max_pages, gfp_flags);
 	if (!lgp->args.layout.pages) {
 		kfree(lgp);