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: 1312721
Change-Id: I42a5d524bcf2a2034fe48ee8454812ca26a98c37
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/14454
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
Smoke: Gluster Build System <jenkins@build.gluster.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 cfb0edd1294..5bca4592461 100644
--- a/xlators/nfs/server/src/nfs-common.c
+++ b/xlators/nfs/server/src/nfs-common.c
@@ -111,25 +111,6 @@ 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 01b49c1eb7a..58536626a0c 100644
--- a/xlators/nfs/server/src/nfs-common.h
+++ b/xlators/nfs/server/src/nfs-common.h
@@ -42,9 +42,6 @@ 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 bf2594f261d..229bfee560a 100644
--- a/xlators/nfs/server/src/nfs3-helpers.c
+++ b/xlators/nfs/server/src/nfs3-helpers.c
@@ -378,7 +378,7 @@ 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));
@@ -399,7 +399,7 @@ 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;