pnfs: support multiple verfs per direct req

Support direct requests that span multiple pnfs data servers by
comparing nfs_pgio_header->verf to a cached verf in pnfs_commit_bucket.
Continue to use dreq->verf if the MDS is used / non-pNFS.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

4 files changed, 109 insertions, 6 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 2c0e08f4cf71..4ad7bc388679 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -108,6 +108,97 @@ static inline int put_dreq(struct nfs_direct_req *dreq)
         return atomic_dec_and_test(&dreq->io_count);
 }
 
+/*
+ * nfs_direct_select_verf - select the right verifier
+ * @dreq - direct request possibly spanning multiple servers
+ * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs
+ * @ds_idx - index of data server in data server list, only valid if ds_clp set
+ *
+ * returns the correct verifier to use given the role of the server
+ */
+static struct nfs_writeverf *
+nfs_direct_select_verf(struct nfs_direct_req *dreq,
+                       struct nfs_client *ds_clp,
+                       int ds_idx)
+{
+        struct nfs_writeverf *verfp = &dreq->verf;
+
+#ifdef CONFIG_NFS_V4_1
+        if (ds_clp) {
+                /* pNFS is in use, use the DS verf */
+                if (ds_idx >= 0 && ds_idx < dreq->ds_cinfo.nbuckets)
+                        verfp = &dreq->ds_cinfo.buckets[ds_idx].direct_verf;
+                else
+                        WARN_ON_ONCE(1);
+        }
+#endif
+        return verfp;
+}
+
+
+/*
+ * nfs_direct_set_hdr_verf - set the write/commit verifier
+ * @dreq - direct request possibly spanning multiple servers
+ * @hdr - pageio header to validate against previously seen verfs
+ *
+ * Set the server's (MDS or DS) "seen" verifier
+ */
+static void nfs_direct_set_hdr_verf(struct nfs_direct_req *dreq,
+                                    struct nfs_pgio_header *hdr)
+{
+        struct nfs_writeverf *verfp;
+
+        verfp = nfs_direct_select_verf(dreq, hdr->data->ds_clp,
+                                      hdr->data->ds_idx);
+        WARN_ON_ONCE(verfp->committed >= 0);
+        memcpy(verfp, &hdr->verf, sizeof(struct nfs_writeverf));
+        WARN_ON_ONCE(verfp->committed < 0);
+}
+
+/*
+ * nfs_direct_cmp_hdr_verf - compare verifier for pgio header
+ * @dreq - direct request possibly spanning multiple servers
+ * @hdr - pageio header to validate against previously seen verf
+ *
+ * set the server's "seen" verf if not initialized.
+ * returns result of comparison between @hdr->verf and the "seen"
+ * verf of the server used by @hdr (DS or MDS)
+ */
+static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq,
+                                          struct nfs_pgio_header *hdr)
+{
+        struct nfs_writeverf *verfp;
+
+        verfp = nfs_direct_select_verf(dreq, hdr->data->ds_clp,
+                                         hdr->data->ds_idx);
+        if (verfp->committed < 0) {
+                nfs_direct_set_hdr_verf(dreq, hdr);
+                return 0;
+        }
+        return memcmp(verfp, &hdr->verf, sizeof(struct nfs_writeverf));
+}
+
+#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
+/*
+ * nfs_direct_cmp_commit_data_verf - compare verifier for commit data
+ * @dreq - direct request possibly spanning multiple servers
+ * @data - commit data to validate against previously seen verf
+ *
+ * returns result of comparison between @data->verf and the verf of
+ * the server used by @data (DS or MDS)
+ */
+static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq,
+                                           struct nfs_commit_data *data)
+{
+        struct nfs_writeverf *verfp;
+
+        verfp = nfs_direct_select_verf(dreq, data->ds_clp,
+                                         data->ds_commit_index);
+        WARN_ON_ONCE(verfp->committed < 0);
+        return memcmp(verfp, &data->verf, sizeof(struct nfs_writeverf));
+}
+#endif
+
 /**
  * nfs_direct_IO - NFS address space operation for direct I/O
  * @rw: direction (read or write)
@@ -168,6 +259,7 @@ static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
         kref_get(&dreq->kref);
         init_completion(&dreq->completion);
         INIT_LIST_HEAD(&dreq->mds_cinfo.list);
+        dreq->verf.committed = NFS_INVALID_STABLE_HOW;  /* not set yet */
         INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
         spin_lock_init(&dreq->lock);
 
@@ -602,7 +694,7 @@ static void nfs_direct_commit_complete(struct nfs_commit_data *data)
                 dprintk("NFS: %5u commit failed with error %d.\n",
                         data->task.tk_pid, status);
                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
-        } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
+        } else if (nfs_direct_cmp_commit_data_verf(dreq, data)) {
                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
         }
@@ -811,13 +903,13 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
                         if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
                                 bit = NFS_IOHDR_NEED_RESCHED;
                         else if (dreq->flags == 0) {
-                                memcpy(&dreq->verf, &hdr->verf,
-                                       sizeof(dreq->verf));
+                                nfs_direct_set_hdr_verf(dreq, hdr);
                                 bit = NFS_IOHDR_NEED_COMMIT;
                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
                         } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
-                                if (memcmp(&dreq->verf, &hdr->verf, sizeof(dreq->verf))) {
-                                        dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+                                if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr)) {
+                                        dreq->flags =
+                                                NFS_ODIRECT_RESCHED_WRITES;
                                         bit = NFS_IOHDR_NEED_RESCHED;
                                 } else
                                         bit = NFS_IOHDR_NEED_COMMIT;
diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 7a665e0f35b7..0ebc521ea6fc 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -560,6 +560,7 @@ filelayout_read_pagelist(struct nfs_pgio_data *data)
         /* No multipath support. Use first DS */
         atomic_inc(&ds->ds_clp->cl_count);
         data->ds_clp = ds->ds_clp;
+        data->ds_idx = idx;
         fh = nfs4_fl_select_ds_fh(lseg, j);
         if (fh)
                 data->args.fh = fh;
@@ -603,6 +604,7 @@ filelayout_write_pagelist(struct nfs_pgio_data *data, int sync)
         data->pgio_done_cb = filelayout_write_done_cb;
         atomic_inc(&ds->ds_clp->cl_count);
         data->ds_clp = ds->ds_clp;
+        data->ds_idx = idx;
         fh = nfs4_fl_select_ds_fh(lseg, j);
         if (fh)
                 data->args.fh = fh;
@@ -875,6 +877,8 @@ filelayout_alloc_commit_info(struct pnfs_layout_segment *lseg,
         for (i = 0; i < size; i++) {
                 INIT_LIST_HEAD(&buckets[i].written);
                 INIT_LIST_HEAD(&buckets[i].committing);
+                /* mark direct verifier as unset */
+                buckets[i].direct_verf.committed = NFS_INVALID_STABLE_HOW;
         }
 
         spin_lock(cinfo->lock);
@@ -885,6 +889,8 @@ filelayout_alloc_commit_info(struct pnfs_layout_segment *lseg,
                             &buckets[i].written);
                 list_splice(&cinfo->ds->buckets[i].committing,
                             &buckets[i].committing);
+                buckets[i].direct_verf.committed =
+                        cinfo->ds->buckets[i].direct_verf.committed;
                 buckets[i].wlseg = cinfo->ds->buckets[i].wlseg;
                 buckets[i].clseg = cinfo->ds->buckets[i].clseg;
         }
diff --git a/include/linux/nfs.h b/include/linux/nfs.h
index 3e794c12e90a..610af5155ef2 100644
--- a/include/linux/nfs.h
+++ b/include/linux/nfs.h
@@ -46,6 +46,9 @@ static inline void nfs_copy_fh(struct nfs_fh *target, const struct nfs_fh *sourc
 enum nfs3_stable_how {
         NFS_UNSTABLE = 0,
         NFS_DATA_SYNC = 1,
-        NFS_FILE_SYNC = 2
+        NFS_FILE_SYNC = 2,
+
+        /* used by direct.c to mark verf as invalid */
+        NFS_INVALID_STABLE_HOW = -1
 };
 #endif /* _LINUX_NFS_H */
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index ae636013fb1f..9a1396e70310 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1112,6 +1112,7 @@ struct pnfs_commit_bucket {
         struct list_head committing;
         struct pnfs_layout_segment *wlseg;
         struct pnfs_layout_segment *clseg;
+        struct nfs_writeverf direct_verf;
 };
 
 struct pnfs_ds_commit_info {
@@ -1294,6 +1295,7 @@ struct nfs_pgio_data {
         __u64                   mds_offset;     /* Filelayout dense stripe */
         struct nfs_page_array   pages;
         struct nfs_client       *ds_clp;        /* pNFS data server */
+        int                     ds_idx;         /* ds index if ds_clp is set */
 };
 
 struct nfs_rw_header {