pNFS/filelayout: Fix coalescing test for single DS

[ Upstream commit a6b9d2fa0024e7e399c26facd0fb466b7396e2b9 ]

When there is a single DS no striping constraints need to be placed on
the IO. When such constraint is applied then buffered reads don't
coalesce to the DS's rsize.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
index d210385..45eec08 100644 (file)
--- a/fs/nfs/filelayout/filelayout.c
+++ b/fs/nfs/filelayout/filelayout.c
@@ -783,6 +783,12 @@ filelayout_alloc_lseg(struct pnfs_layout_hdr *layoutid,
        return &fl->generic_hdr;
 }
 
        return &fl->generic_hdr;
 }
 

+static bool
+filelayout_lseg_is_striped(const struct nfs4_filelayout_segment *flseg)
+{
+       return flseg->num_fh > 1;
+}
+

 /*
  * filelayout_pg_test(). Called by nfs_can_coalesce_requests()
  *
 /*
  * filelayout_pg_test(). Called by nfs_can_coalesce_requests()
  *


@@ -803,6 +809,8 @@ filelayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
        size = pnfs_generic_pg_test(pgio, prev, req);
        if (!size)
                return 0;
        size = pnfs_generic_pg_test(pgio, prev, req);
        if (!size)
                return 0;

+       else if (!filelayout_lseg_is_striped(FILELAYOUT_LSEG(pgio->pg_lseg)))
+               return size;

 
        /* see if req and prev are in the same stripe */
        if (prev) {
 
        /* see if req and prev are in the same stripe */
        if (prev) {