dht: Fix stale-layout and create issue

Problem: With lookup-optimize set to on by default, a client with
stale-layout can create a new file on a wrong subvol. This will lead to
possible duplicate files if two different clients attempt to create the
same file with two different layouts.

Solution: Send in-memory layout to be cross checked at posix before
commiting a "create". In case of a mismatch, sync the client layout with
that of the server and attempt the create fop one more time.

test: Manual, testcase(attached)

fixes: bz#1786679
Change-Id: Ife0941f105113f1c572f4363cbcee65e0dd9bd6a
Signed-off-by: Susant Palai <spalai@redhat.com>

1 files changed, 28 insertions, 1 deletions

diff --git a/xlators/storage/posix/src/posix-entry-ops.c b/xlators/storage/posix/src/posix-entry-ops.c
index 1f1e05f1dc9..667fec7d62f 100644
--- a/xlators/storage/posix/src/posix-entry-ops.c
+++ b/xlators/storage/posix/src/posix-entry-ops.c
@@ -2145,6 +2145,8 @@ posix_create(call_frame_t *frame, xlator_t *this, loc_t *loc, int32_t flags,
         0,
     };
 
+    dict_t *xdata_rsp = dict_ref(xdata);
+
     DECLARE_OLD_FS_ID_VAR;
 
     VALIDATE_OR_GOTO(frame, out);
@@ -2194,6 +2196,28 @@ posix_create(call_frame_t *frame, xlator_t *this, loc_t *loc, int32_t flags,
         was_present = 0;
     }
 
+    if (!was_present) {
+        if (posix_is_layout_stale(xdata, par_path, this)) {
+            op_ret = -1;
+            op_errno = EIO;
+            if (!xdata_rsp) {
+                xdata_rsp = dict_new();
+                if (!xdata_rsp) {
+                    op_errno = ENOMEM;
+                    goto out;
+                }
+            }
+
+            if (dict_set_int32_sizen(xdata_rsp, GF_PREOP_CHECK_FAILED, 1) ==
+                -1) {
+                gf_msg(this->name, GF_LOG_ERROR, errno, P_MSG_DICT_SET_FAILED,
+                       "setting key %s in dict failed", GF_PREOP_CHECK_FAILED);
+            }
+
+            goto out;
+        }
+    }
+
     if (priv->o_direct)
         _flags |= O_DIRECT;
 
@@ -2313,7 +2337,10 @@ out:
 
     STACK_UNWIND_STRICT(create, frame, op_ret, op_errno, fd,
                         (loc) ? loc->inode : NULL, &stbuf, &preparent,
-                        &postparent, xdata);
+                        &postparent, xdata_rsp);
+
+    if (xdata_rsp)
+        dict_unref(xdata_rsp);
 
     return 0;
 }