NFS/flexfiles: Simplify nfs4_ff_layout_select_ds_fh()

Pass in a pointer to the mirror rather than having to retrieve it from
the array and then verify the resulting pointer.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -1795,7 +1795,7 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
 	hdr->pgio_done_cb = ff_layout_read_done_cb;
 	refcount_inc(&ds->ds_clp->cl_count);
 	hdr->ds_clp = ds->ds_clp;
-	fh = nfs4_ff_layout_select_ds_fh(lseg, idx);
+	fh = nfs4_ff_layout_select_ds_fh(mirror);
 	if (fh)
 		hdr->args.fh = fh;
 
@@ -1863,7 +1863,7 @@ ff_layout_write_pagelist(struct nfs_pgio_header *hdr, int sync)
 	refcount_inc(&ds->ds_clp->cl_count);
 	hdr->ds_clp = ds->ds_clp;
 	hdr->ds_commit_idx = idx;
-	fh = nfs4_ff_layout_select_ds_fh(lseg, idx);
+	fh = nfs4_ff_layout_select_ds_fh(mirror);
 	if (fh)
 		hdr->args.fh = fh;
 

fs/nfs/flexfilelayout/flexfilelayout.h

@@ -203,7 +203,7 @@ unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
 		struct list_head *head,
 		unsigned int maxnum);
 struct nfs_fh *
-nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx);
+nfs4_ff_layout_select_ds_fh(struct nfs4_ff_layout_mirror *mirror);
 int
 nfs4_ff_layout_select_ds_stateid(struct pnfs_layout_segment *lseg,
 				u32 mirror_idx,

fs/nfs/flexfilelayout/flexfilelayoutdev.c

@@ -351,21 +351,10 @@ ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode)
 }
 
 struct nfs_fh *
-nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx)
+nfs4_ff_layout_select_ds_fh(struct nfs4_ff_layout_mirror *mirror)
 {
-	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, mirror_idx);
-	struct nfs_fh *fh = NULL;
-
-	if (!ff_layout_mirror_valid(lseg, mirror, false)) {
-		pr_err_ratelimited("NFS: %s: No data server for mirror offset index %d\n",
-			__func__, mirror_idx);
-		goto out;
-	}
-
 	/* FIXME: For now assume there is only 1 version available for the DS */
-	fh = &mirror->fh_versions[0];
-out:
-	return fh;
+	return &mirror->fh_versions[0];
 }
 
 int