Revert "storage/posix: Remove the interim fix that handles the gfid race"

This reverts commit 97807e75956a2d240282bc64fab1b71762de0546.

In a distribute or distribute-replica volume, this fix is required to prevent
gfid mis-match due to race issues.

test script bug-767585-gfid.t  needs a sleep of 2, cause after setting backend
gfid directly, we try to heal, and with this fix, we do not allow setxattr of
gfid within creation of 1 second if not created by itself

Change-Id: Ie3f4b385416889fd5de444638a64a7eaaf24cd60
BUG: 951195
Signed-off-by: shishir gowda <sgowda@redhat.com>
Reviewed-on: http://review.gluster.org/5240
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>

3 files changed, 70 insertions, 2 deletions

diff --git a/xlators/storage/posix/src/posix-helpers.c b/xlators/storage/posix/src/posix-helpers.c
index 616664a3d8d..2fa55eda0ac 100644
--- a/xlators/storage/posix/src/posix-helpers.c
+++ b/xlators/storage/posix/src/posix-helpers.c
@@ -901,6 +901,74 @@ unlock:
         UNLOCK (&priv->lock);
 }
 
+static int
+is_fresh_file (struct stat *stat)
+{
+        struct timeval tv;
+
+        gettimeofday (&tv, NULL);
+
+        if ((stat->st_ctime >= (tv.tv_sec - 1))
+            && (stat->st_ctime <= tv.tv_sec))
+                return 1;
+
+        return 0;
+}
+
+
+int
+posix_gfid_heal (xlator_t *this, const char *path, loc_t *loc, dict_t *xattr_req)
+{
+        /* The purpose of this function is to prevent a race
+           where an inode creation FOP (like mkdir/mknod/create etc)
+           races with lookup in the following way:
+
+                   {create thread}       |    {lookup thread}
+                                         |
+                                         t0
+                      mkdir ("name")     |
+                                         t1
+                                         |     posix_gfid_set ("name", 2);
+                                         t2
+             posix_gfid_set ("name", 1); |
+                                         t3
+                      lstat ("name");    |     lstat ("name");
+
+          In the above case mkdir FOP would have resulted with GFID 2 while
+          it should have been GFID 1. It matters in the case where GFID would
+          have gotten set to 1 on other subvolumes of replciate/distribute
+
+          The "solution" here is that, if we detect lookup is attempting to
+          set a GFID on a file which is created very recently, but does not
+          yet have a GFID (i.e, between t1 and t2), then "fake" it as though
+          posix_gfid_heal was called at t0 instead.
+        */
+
+        uuid_t       uuid_curr;
+        int          ret = 0;
+        struct stat  stat = {0, };
+
+        if (!xattr_req)
+                goto out;
+
+        if (sys_lstat (path, &stat) != 0)
+                goto out;
+
+        ret = sys_lgetxattr (path, GFID_XATTR_KEY, uuid_curr, 16);
+        if (ret != 16) {
+                if (is_fresh_file (&stat)) {
+                        ret = -1;
+                        errno = ENOENT;
+                        goto out;
+                }
+        }
+
+        ret = posix_gfid_set (this, path, loc, xattr_req);
+out:
+        return ret;
+}
+
+
 int
 posix_acl_xattr_set (xlator_t *this, const char *path, dict_t *xattr_req)
 {
diff --git a/xlators/storage/posix/src/posix.c b/xlators/storage/posix/src/posix.c
index e917766b5fe..0a7030213b5 100644
--- a/xlators/storage/posix/src/posix.c
+++ b/xlators/storage/posix/src/posix.c
@@ -129,7 +129,7 @@ posix_lookup (call_frame_t *frame, xlator_t *this,
                 MAKE_ENTRY_HANDLE (real_path, par_path, this, loc, &buf);
 
                 if (uuid_is_null (loc->inode->gfid)) {
-                        posix_gfid_set (this, real_path, loc, xdata);
+                        posix_gfid_heal (this, real_path, loc, xdata);
                         MAKE_ENTRY_HANDLE (real_path, par_path, this,
                                            loc, &buf);
                 }
diff --git a/xlators/storage/posix/src/posix.h b/xlators/storage/posix/src/posix.h
index c834b29d90e..a957e18768c 100644
--- a/xlators/storage/posix/src/posix.h
+++ b/xlators/storage/posix/src/posix.h
@@ -188,7 +188,7 @@ int posix_get_file_contents (xlator_t *this, uuid_t pargfid,
 int posix_set_file_contents (xlator_t *this, const char *path, char *key,
                              data_t *value, int flags);
 int posix_acl_xattr_set (xlator_t *this, const char *path, dict_t *xattr_req);
-int posix_gfid_heal (xlator_t *this, const char *path, dict_t *xattr_req);
+int posix_gfid_heal (xlator_t *this, const char *path, loc_t *loc, dict_t *xattr_req);
 int posix_entry_create_xattr_set (xlator_t *this, const char *path,
                                   dict_t *dict);