cluster/afr: Don't let NFS cache stat after writes

Problem:
Afr does post-ops after write but the stat buffer it unwinds is at the
time of write, so if nfs client caches this, it will see different
ctime when it does stat on it after post-op is done. From NFS client's
perspective it thinks the file is changed. Tar which depends on this
to be correct keeps giving 'file changed as we read it' warning.
If Afr instead has to choose to unwind after post-op, eager-lock,
delayed-post-op will have to be disabled which will lead to bad
performance for all write usecases.

Fix:
Don't let client cache stat after write.

 >Change-Id: Ic6062acc6e5cdd97a9c83c56bd529ec83cee8a23
 >BUG: 1302948
 >Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
 >Signed-off-by: Anuradha Talur <atalur@redhat.com>
 >Reviewed-on: http://review.gluster.org/13785
 >Smoke: Gluster Build System <jenkins@build.gluster.com>
 >NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
 >CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
 >Reviewed-by: Niels de Vos <ndevos@redhat.com>

BUG: 1335285
Change-Id: Ibef4fc80496d12acd15db57713af2e3a1c9109a7
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/14300
Smoke: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>

3 files changed, 2 insertions, 24 deletions

diff --git a/xlators/nfs/server/src/nfs-common.c b/xlators/nfs/server/src/nfs-common.c
index 51a2b7e36f7..d9ea1e1ac47 100644
--- a/xlators/nfs/server/src/nfs-common.c
+++ b/xlators/nfs/server/src/nfs-common.c
@@ -106,25 +106,6 @@ nfs_mntpath_to_xlator (xlator_list_t *cl, char *path)
 }
 
 
-/* Returns 1 if the stat seems to be filled with zeroes. */
-int
-nfs_zero_filled_stat (struct iatt *buf)
-{
-        if (!buf)
-                return 1;
-
-        /* Do not use st_dev because it is transformed to store the xlator id
-         * in place of the device number. Do not use st_ino because by this time
-         * we've already mapped the root ino to 1 so it is not guaranteed to be
-         * 0.
-         */
-        if ((buf->ia_nlink == 0) && (buf->ia_ctime == 0))
-                return 1;
-
-        return 0;
-}
-
-
 void
 nfs_loc_wipe (loc_t *loc)
 {
diff --git a/xlators/nfs/server/src/nfs-common.h b/xlators/nfs/server/src/nfs-common.h
index fa7f4ebf212..77bdfb0bbf0 100644
--- a/xlators/nfs/server/src/nfs-common.h
+++ b/xlators/nfs/server/src/nfs-common.h
@@ -37,9 +37,6 @@ nfs_path_to_xlator (xlator_list_t *cl, char *path);
 extern xlator_t *
 nfs_mntpath_to_xlator (xlator_list_t *cl, char *path);
 
-extern int
-nfs_zero_filled_stat (struct iatt *buf);
-
 extern void
 nfs_loc_wipe (loc_t *loc);
 
diff --git a/xlators/nfs/server/src/nfs3-helpers.c b/xlators/nfs/server/src/nfs3-helpers.c
index 7eb491142f7..ad4c87e69d7 100644
--- a/xlators/nfs/server/src/nfs3-helpers.c
+++ b/xlators/nfs/server/src/nfs3-helpers.c
@@ -373,7 +373,7 @@ nfs3_stat_to_post_op_attr (struct iatt *buf)
          * returning these zeroed out attrs.
          */
         attr.attributes_follow = FALSE;
-        if (nfs_zero_filled_stat (buf))
+        if (gf_is_zero_filled_stat (buf))
                 goto out;
 
         nfs3_stat_to_fattr3 (buf, &(attr.post_op_attr_u.attributes));
@@ -394,7 +394,7 @@ nfs3_stat_to_pre_op_attr (struct iatt *pre)
          * returning these zeroed out attrs.
          */
         poa.attributes_follow = FALSE;
-        if (nfs_zero_filled_stat (pre))
+        if (gf_is_zero_filled_stat (pre))
                 goto out;
 
         poa.attributes_follow = TRUE;