NFS/flexfiles: refactor calls to fs4_ff_layout_prepare_ds()

While we may want to skip attempting to connect to a downed mirror
when we're deciding which mirror to select for a read, we do not
want to do so once we've committed to attempting the I/O in
ff_layout_read/write_pagelist(), or ff_layout_initiate_commit()
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -794,6 +794,7 @@ ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
 				  int *best_idx)
 {
 	struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);
+	struct nfs4_ff_layout_mirror *mirror;
 	struct nfs4_pnfs_ds *ds;
 	bool fail_return = false;
 	int idx;
@@ -802,7 +803,12 @@ ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
 	for (idx = start_idx; idx < fls->mirror_array_cnt; idx++) {
 		if (idx+1 == fls->mirror_array_cnt)
 			fail_return = true;
-		ds = nfs4_ff_layout_prepare_ds(lseg, idx, fail_return);
+
+		mirror = FF_LAYOUT_COMP(lseg, idx);
+		if (ff_layout_test_devid_unavailable(&mirror->mirror_ds->id_node))
+			continue;
+
+		ds = nfs4_ff_layout_prepare_ds(lseg, mirror, fail_return);
 		if (ds) {
 			*best_idx = idx;
 			return ds;
@@ -925,7 +931,10 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
 		goto out_mds;
 
 	for (i = 0; i < pgio->pg_mirror_count; i++) {
-		ds = nfs4_ff_layout_prepare_ds(pgio->pg_lseg, i, true);
+		mirror = FF_LAYOUT_COMP(pgio->pg_lseg, i);
+		if (ff_layout_test_devid_unavailable(&mirror->mirror_ds->id_node))
+			continue;
+		ds = nfs4_ff_layout_prepare_ds(pgio->pg_lseg, mirror, true);
 		if (!ds) {
 			if (!ff_layout_no_fallback_to_mds(pgio->pg_lseg))
 				goto out_mds;
@@ -936,7 +945,6 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
 			goto retry;
 		}
 		pgm = &pgio->pg_mirrors[i];
-		mirror = FF_LAYOUT_COMP(pgio->pg_lseg, i);
 		pgm->pg_bsize = mirror->mirror_ds->ds_versions[0].wsize;
 	}
 
@@ -1724,6 +1732,7 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
 	struct pnfs_layout_segment *lseg = hdr->lseg;
 	struct nfs4_pnfs_ds *ds;
 	struct rpc_clnt *ds_clnt;
+	struct nfs4_ff_layout_mirror *mirror;
 	const struct cred *ds_cred;
 	loff_t offset = hdr->args.offset;
 	u32 idx = hdr->pgio_mirror_idx;
@@ -1734,7 +1743,8 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
 		__func__, hdr->inode->i_ino,
 		hdr->args.pgbase, (size_t)hdr->args.count, offset);
 
-	ds = nfs4_ff_layout_prepare_ds(lseg, idx, false);
+	mirror = FF_LAYOUT_COMP(lseg, idx);
+	ds = nfs4_ff_layout_prepare_ds(lseg, mirror, false);
 	if (!ds)
 		goto out_failed;
 
@@ -1791,13 +1801,15 @@ ff_layout_write_pagelist(struct nfs_pgio_header *hdr, int sync)
 	struct pnfs_layout_segment *lseg = hdr->lseg;
 	struct nfs4_pnfs_ds *ds;
 	struct rpc_clnt *ds_clnt;
+	struct nfs4_ff_layout_mirror *mirror;
 	const struct cred *ds_cred;
 	loff_t offset = hdr->args.offset;
 	int vers;
 	struct nfs_fh *fh;
 	int idx = hdr->pgio_mirror_idx;
 
-	ds = nfs4_ff_layout_prepare_ds(lseg, idx, true);
+	mirror = FF_LAYOUT_COMP(lseg, idx);
+	ds = nfs4_ff_layout_prepare_ds(lseg, mirror, true);
 	if (!ds)
 		goto out_failed;
 
@@ -1870,6 +1882,7 @@ static int ff_layout_initiate_commit(struct nfs_commit_data *data, int how)
 	struct pnfs_layout_segment *lseg = data->lseg;
 	struct nfs4_pnfs_ds *ds;
 	struct rpc_clnt *ds_clnt;
+	struct nfs4_ff_layout_mirror *mirror;
 	const struct cred *ds_cred;
 	u32 idx;
 	int vers, ret;
@@ -1880,7 +1893,8 @@ static int ff_layout_initiate_commit(struct nfs_commit_data *data, int how)
 		goto out_err;
 
 	idx = calc_ds_index_from_commit(lseg, data->ds_commit_index);
-	ds = nfs4_ff_layout_prepare_ds(lseg, idx, true);
+	mirror = FF_LAYOUT_COMP(lseg, idx);
+	ds = nfs4_ff_layout_prepare_ds(lseg, mirror, true);
 	if (!ds)
 		goto out_err;
 

fs/nfs/flexfilelayout/flexfilelayout.h

@@ -228,7 +228,8 @@ nfs4_ff_layout_select_ds_stateid(struct pnfs_layout_segment *lseg,
 				nfs4_stateid *stateid);
 
 struct nfs4_pnfs_ds *
-nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
+nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg,
+			  struct nfs4_ff_layout_mirror *mirror,
 			  bool fail_return);
 
 struct rpc_clnt *

fs/nfs/flexfilelayout/flexfilelayoutdev.c

@@ -391,7 +391,7 @@ nfs4_ff_layout_select_ds_stateid(struct pnfs_layout_segment *lseg,
 /**
  * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call
  * @lseg: the layout segment we're operating on
- * @ds_idx: index of the DS to use
+ * @mirror: layout mirror describing the DS to use
  * @fail_return: return layout on connect failure?
  *
  * Try to prepare a DS connection to accept an RPC call. This involves
@@ -406,26 +406,18 @@ nfs4_ff_layout_select_ds_stateid(struct pnfs_layout_segment *lseg,
  * Returns a pointer to a connected DS object on success or NULL on failure.
  */
 struct nfs4_pnfs_ds *
-nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
+nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg,
+			  struct nfs4_ff_layout_mirror *mirror,
 			  bool fail_return)
 {
-	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 	struct nfs4_pnfs_ds *ds = NULL;
-	struct nfs4_deviceid_node *devid;
 	struct inode *ino = lseg->pls_layout->plh_inode;
 	struct nfs_server *s = NFS_SERVER(ino);
 	unsigned int max_payload;
 	int status;
 
-	if (!ff_layout_mirror_valid(lseg, mirror, true)) {
-		pr_err_ratelimited("NFS: %s: No data server for offset index %d\n",
-			__func__, ds_idx);
+	if (!ff_layout_mirror_valid(lseg, mirror, true))
 		goto out;
-	}
-
-	devid = &mirror->mirror_ds->id_node;
-	if (ff_layout_test_devid_unavailable(devid))
-		goto out_fail;
 
 	ds = mirror->mirror_ds->ds;
 	/* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
@@ -436,8 +428,8 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
 	/* FIXME: For now we assume the server sent only one version of NFS
 	 * to use for the DS.
 	 */
-	status = nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
-			     dataserver_retrans,
+	status = nfs4_pnfs_ds_connect(s, ds, &mirror->mirror_ds->id_node,
+			     dataserver_timeo, dataserver_retrans,
 			     mirror->mirror_ds->ds_versions[0].version,
 			     mirror->mirror_ds->ds_versions[0].minor_version);
 
@@ -452,7 +444,6 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
 			mirror->mirror_ds->ds_versions[0].wsize = max_payload;
 		goto out;
 	}
-out_fail:
 	ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
 				 mirror, lseg->pls_range.offset,
 				 lseg->pls_range.length, NFS4ERR_NXIO,