pnfs: pnfs_update_layout needs to consider if strict iomode checking is on

As flexfiles has FF_FLAGS_NO_READ_IO, there is a need to generically
support enforcing that a IOMODE_RW segment will not allow READ I/O.

Signed-off-by: Tom Haynes <loghyr@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

4 files changed, 61 insertions, 25 deletions

diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
index 3e50057eeadf..aa59757389dc 100644
--- a/fs/nfs/filelayout/filelayout.c
+++ b/fs/nfs/filelayout/filelayout.c
@@ -890,6 +890,7 @@ filelayout_pg_init_read(struct nfs_pageio_descriptor *pgio,
                                            0,
                                            NFS4_MAX_UINT64,
                                            IOMODE_READ,
+                                           false,
                                            GFP_KERNEL);
                 if (IS_ERR(pgio->pg_lseg)) {
                         pgio->pg_error = PTR_ERR(pgio->pg_lseg);
@@ -915,6 +916,7 @@ filelayout_pg_init_write(struct nfs_pageio_descriptor *pgio,
                                            0,
                                            NFS4_MAX_UINT64,
                                            IOMODE_RW,
+                                           false,
                                            GFP_NOFS);
                 if (IS_ERR(pgio->pg_lseg)) {
                         pgio->pg_error = PTR_ERR(pgio->pg_lseg);
diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index a7aeb7407252..0e8018bc9880 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -821,6 +821,36 @@ ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
 }
 
 static void
+ff_layout_pg_get_read(struct nfs_pageio_descriptor *pgio,
+                      struct nfs_page *req,
+                      bool strict_iomode)
+{
+retry_strict:
+        pnfs_put_lseg(pgio->pg_lseg);
+        pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+                                           req->wb_context,
+                                           0,
+                                           NFS4_MAX_UINT64,
+                                           IOMODE_READ,
+                                           strict_iomode,
+                                           GFP_KERNEL);
+        if (IS_ERR(pgio->pg_lseg)) {
+                pgio->pg_error = PTR_ERR(pgio->pg_lseg);
+                pgio->pg_lseg = NULL;
+        }
+
+        /* If we don't have checking, do get a IOMODE_RW
+         * segment, and the server wants to avoid READs
+         * there, then retry!
+         */
+        if (pgio->pg_lseg && !strict_iomode &&
+            ff_layout_avoid_read_on_rw(pgio->pg_lseg)) {
+                strict_iomode = true;
+                goto retry_strict;
+        }
+}
+
+static void
 ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio,
                         struct nfs_page *req)
 {
@@ -830,19 +860,10 @@ ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio,
         int ds_idx;
 
         /* Use full layout for now */
-        if (!pgio->pg_lseg || ff_layout_avoid_read_on_rw(pgio->pg_lseg)) {
-                pnfs_put_lseg(pgio->pg_lseg);
-                pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
-                                                   req->wb_context,
-                                                   0,
-                                                   NFS4_MAX_UINT64,
-                                                   IOMODE_READ,
-                                                   GFP_KERNEL);
-                if (IS_ERR(pgio->pg_lseg)) {
-                        pgio->pg_error = PTR_ERR(pgio->pg_lseg);
-                        pgio->pg_lseg = NULL;
-                }
-        }
+        if (!pgio->pg_lseg)
+                ff_layout_pg_get_read(pgio, req, false);
+        else if (ff_layout_avoid_read_on_rw(pgio->pg_lseg))
+                ff_layout_pg_get_read(pgio, req, true);
 
         /* If no lseg, fall back to read through mds */
         if (pgio->pg_lseg == NULL)
@@ -894,6 +915,7 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
                                                    0,
                                                    NFS4_MAX_UINT64,
                                                    IOMODE_RW,
+                                                   false,
                                                    GFP_NOFS);
                 if (IS_ERR(pgio->pg_lseg)) {
                         pgio->pg_error = PTR_ERR(pgio->pg_lseg);
@@ -952,6 +974,7 @@ ff_layout_pg_get_mirror_count_write(struct nfs_pageio_descriptor *pgio,
                                                    0,
                                                    NFS4_MAX_UINT64,
                                                    IOMODE_RW,
+                                                   false,
                                                    GFP_NOFS);
                 if (IS_ERR(pgio->pg_lseg)) {
                         pgio->pg_error = PTR_ERR(pgio->pg_lseg);
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 79ae3049608d..0c7e0d45a4de 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1321,23 +1321,28 @@ out_existing:
 
 /*
  * iomode matching rules:
- * iomode       lseg    match
- * -----        -----   -----
- * ANY          READ    true
- * ANY          RW      true
- * RW           READ    false
- * RW           RW      true
- * READ         READ    true
- * READ         RW      true
+ * iomode       lseg    strict match
+ *                      iomode
+ * -----        -----   ------ -----
+ * ANY          READ    N/A    true
+ * ANY          RW      N/A    true
+ * RW           READ    N/A    false
+ * RW           RW      N/A    true
+ * READ         READ    N/A    true
+ * READ         RW      true   false
+ * READ         RW      false  true
  */
 static bool
 pnfs_lseg_range_match(const struct pnfs_layout_range *ls_range,
-                 const struct pnfs_layout_range *range)
+                 const struct pnfs_layout_range *range,
+                 bool strict_iomode)
 {
         struct pnfs_layout_range range1;
 
         if ((range->iomode == IOMODE_RW &&
              ls_range->iomode != IOMODE_RW) ||
+            (range->iomode != ls_range->iomode &&
+             strict_iomode == true) ||
             !pnfs_lseg_range_intersecting(ls_range, range))
                 return 0;
 
@@ -1352,7 +1357,8 @@ pnfs_lseg_range_match(const struct pnfs_layout_range *ls_range,
  */
 static struct pnfs_layout_segment *
 pnfs_find_lseg(struct pnfs_layout_hdr *lo,
-                struct pnfs_layout_range *range)
+                struct pnfs_layout_range *range,
+                bool strict_iomode)
 {
         struct pnfs_layout_segment *lseg, *ret = NULL;
 
@@ -1361,7 +1367,8 @@ pnfs_find_lseg(struct pnfs_layout_hdr *lo,
         list_for_each_entry(lseg, &lo->plh_segs, pls_list) {
                 if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags) &&
                     !test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags) &&
-                    pnfs_lseg_range_match(&lseg->pls_range, range)) {
+                    pnfs_lseg_range_match(&lseg->pls_range, range,
+                                          strict_iomode)) {
                         ret = pnfs_get_lseg(lseg);
                         break;
                 }
@@ -1478,6 +1485,7 @@ pnfs_update_layout(struct inode *ino,
                    loff_t pos,
                    u64 count,
                    enum pnfs_iomode iomode,
+                   bool strict_iomode,
                    gfp_t gfp_flags)
 {
         struct pnfs_layout_range arg = {
@@ -1539,7 +1547,7 @@ lookup_again:
                 goto out_unlock;
         }
 
-        lseg = pnfs_find_lseg(lo, &arg);
+        lseg = pnfs_find_lseg(lo, &arg, strict_iomode);
         if (lseg) {
                 trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
                                 PNFS_UPDATE_LAYOUT_FOUND_CACHED);
@@ -1883,6 +1891,7 @@ pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *r
                                                    req_offset(req),
                                                    rd_size,
                                                    IOMODE_READ,
+                                                   false,
                                                    GFP_KERNEL);
                 if (IS_ERR(pgio->pg_lseg)) {
                         pgio->pg_error = PTR_ERR(pgio->pg_lseg);
@@ -1907,6 +1916,7 @@ pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,
                                                    req_offset(req),
                                                    wb_size,
                                                    IOMODE_RW,
+                                                   false,
                                                    GFP_NOFS);
                 if (IS_ERR(pgio->pg_lseg)) {
                         pgio->pg_error = PTR_ERR(pgio->pg_lseg);
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index f9f3331bef49..b21bd0bee784 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -288,6 +288,7 @@ struct pnfs_layout_segment *pnfs_update_layout(struct inode *ino,
                                                loff_t pos,
                                                u64 count,
                                                enum pnfs_iomode iomode,
+                                               bool strict_iomode,
                                                gfp_t gfp_flags);
 void pnfs_clear_layoutreturn_waitbit(struct pnfs_layout_hdr *lo);