pNFS/flexfiles: Fix an Oopsable condition when connection to the DS fails

If the attempt to connect to a DS fails inside ff_layout_pg_init_read or
ff_layout_pg_init_write, then we currently end up clearing the layout
segment carried by the struct nfs_pageio_descriptor, causing an Oops
when we later call into ff_layout_read_pagelist/ff_layout_write_pagelist.

The fix is to ensure we return the layout and then retry.

Fixes: 446ca2195303 ("pNFS/flexfiles: When initing reads or writes, we...")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index ee1c94c7614cf4df962b501937a6021173efe9f0..51b51369704c56c00732b10ff0c31edfd0d9c19e 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -806,11 +806,14 @@ ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
 {
        struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);
        struct nfs4_pnfs_ds *ds;
+       bool fail_return = false;
        int idx;
 
        /* mirrors are sorted by efficiency */
        for (idx = start_idx; idx < fls->mirror_array_cnt; idx++) {
-               ds = nfs4_ff_layout_prepare_ds(lseg, idx, false);
+               if (idx+1 == fls->mirror_array_cnt)
+                       fail_return = true;
+               ds = nfs4_ff_layout_prepare_ds(lseg, idx, fail_return);
                if (ds) {
                        *best_idx = idx;
                        return ds;
@@ -859,6 +862,7 @@ ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio,
        struct nfs4_pnfs_ds *ds;
        int ds_idx;
 
+retry:
        /* Use full layout for now */
        if (!pgio->pg_lseg)
                ff_layout_pg_get_read(pgio, req, false);
@@ -871,10 +875,13 @@ ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio,
 
        ds = ff_layout_choose_best_ds_for_read(pgio->pg_lseg, 0, &ds_idx);
        if (!ds) {
-               if (ff_layout_no_fallback_to_mds(pgio->pg_lseg))
-                       goto out_pnfs;
-               else
+               if (!ff_layout_no_fallback_to_mds(pgio->pg_lseg))
                        goto out_mds;
+               pnfs_put_lseg(pgio->pg_lseg);
+               pgio->pg_lseg = NULL;
+               /* Sleep for 1 second before retrying */
+               ssleep(1);
+               goto retry;
        }
 
        mirror = FF_LAYOUT_COMP(pgio->pg_lseg, ds_idx);
@@ -890,12 +897,6 @@ out_mds:
        pnfs_put_lseg(pgio->pg_lseg);
        pgio->pg_lseg = NULL;
        nfs_pageio_reset_read_mds(pgio);
-       return;
-
-out_pnfs:
-       pnfs_set_lo_fail(pgio->pg_lseg);
-       pnfs_put_lseg(pgio->pg_lseg);
-       pgio->pg_lseg = NULL;
 }
 
 static void
@@ -909,6 +910,7 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
        int i;
        int status;
 
+retry:
        if (!pgio->pg_lseg) {
                pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                                   req->wb_context,
@@ -940,10 +942,13 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
        for (i = 0; i < pgio->pg_mirror_count; i++) {
                ds = nfs4_ff_layout_prepare_ds(pgio->pg_lseg, i, true);
                if (!ds) {
-                       if (ff_layout_no_fallback_to_mds(pgio->pg_lseg))
-                               goto out_pnfs;
-                       else
+                       if (!ff_layout_no_fallback_to_mds(pgio->pg_lseg))
                                goto out_mds;
+                       pnfs_put_lseg(pgio->pg_lseg);
+                       pgio->pg_lseg = NULL;
+                       /* Sleep for 1 second before retrying */
+                       ssleep(1);
+                       goto retry;
                }
                pgm = &pgio->pg_mirrors[i];
                mirror = FF_LAYOUT_COMP(pgio->pg_lseg, i);
@@ -956,12 +961,6 @@ out_mds:
        pnfs_put_lseg(pgio->pg_lseg);
        pgio->pg_lseg = NULL;
        nfs_pageio_reset_write_mds(pgio);
-       return;
-
-out_pnfs:
-       pnfs_set_lo_fail(pgio->pg_lseg);
-       pnfs_put_lseg(pgio->pg_lseg);
-       pgio->pg_lseg = NULL;
 }
 
 static unsigned int

diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index 970efba05ae12da94cbe396f5fd9165393789272..f7a3f6b05369a21d7e1190625e5871c55d1aeeb2 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -379,7 +379,7 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
 
        devid = &mirror->mirror_ds->id_node;
        if (ff_layout_test_devid_unavailable(devid))
-               goto out;
+               goto out_fail;
 
        ds = mirror->mirror_ds->ds;
        /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
@@ -405,15 +405,16 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
                        mirror->mirror_ds->ds_versions[0].rsize = max_payload;
                if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
                        mirror->mirror_ds->ds_versions[0].wsize = max_payload;
-       } else {
-               ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
-                                        mirror, lseg->pls_range.offset,
-                                        lseg->pls_range.length, NFS4ERR_NXIO,
-                                        OP_ILLEGAL, GFP_NOIO);
-               if (fail_return || !ff_layout_has_available_ds(lseg))
-                       pnfs_error_mark_layout_for_return(ino, lseg);
-               ds = NULL;
+               goto out;
        }
+       ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
+                                mirror, lseg->pls_range.offset,
+                                lseg->pls_range.length, NFS4ERR_NXIO,
+                                OP_ILLEGAL, GFP_NOIO);
+out_fail:
+       if (fail_return || !ff_layout_has_available_ds(lseg))
+               pnfs_error_mark_layout_for_return(ino, lseg);
+       ds = NULL;
 out:
        return ds;
 }