Commit 64294b08 authored Feb 02, 2017 by Trond Myklebust Committed by Trond Myklebust May 31, 2018

pNFS: Don't send LAYOUTGET on OPEN for read, if we already have cached data



If we're only opening the file for reading, and the file is empty and/or
we already have cached data, then heuristically optimise away the
LAYOUTGET.

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

parent 8dc96566

fs/nfs/pnfs.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -2046,6 +2046,11 @@ static void _lgopen_prepare_attached(struct nfs4_opendata *data,
		struct nfs4_layoutget *lgp;
		struct pnfs_layout_hdr *lo;

		/* Heuristic: don't send layoutget if we have cached data */
		if (rng.iomode == IOMODE_READ &&
		(i_size_read(ino) == 0 \|\| ino->i_mapping->nrpages != 0))
		return;

		lo = _pnfs_grab_empty_layout(ino, ctx);
		if (!lo)
		return;