ocfs2: Add a mount option "coherency=*" to handle cluster coherency for O_DIRECT writes.
Currently, the default behavior of O_DIRECT writes was allowing
concurrent writing among nodes to the same file, with no cluster
coherency guaranteed (no EX lock held). This can leave stale data in
the cache for buffered reads on other nodes.
The new mount option introduce a chance to choose two different
behaviors for O_DIRECT writes:
* coherency=full, as the default value, will disallow
concurrent O_DIRECT writes by taking
EX locks.
* coherency=buffered, allow concurrent O_DIRECT writes
without EX lock among nodes, which
gains high performance at risk of
getting stale data on other nodes.
Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index b578644..9122d59 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -177,6 +177,8 @@
Opt_noacl,
Opt_usrquota,
Opt_grpquota,
+ Opt_coherency_buffered,
+ Opt_coherency_full,
Opt_resv_level,
Opt_dir_resv_level,
Opt_err,
@@ -205,6 +207,8 @@
{Opt_noacl, "noacl"},
{Opt_usrquota, "usrquota"},
{Opt_grpquota, "grpquota"},
+ {Opt_coherency_buffered, "coherency=buffered"},
+ {Opt_coherency_full, "coherency=full"},
{Opt_resv_level, "resv_level=%u"},
{Opt_dir_resv_level, "dir_resv_level=%u"},
{Opt_err, NULL}
@@ -1452,6 +1456,12 @@
case Opt_grpquota:
mopt->mount_opt |= OCFS2_MOUNT_GRPQUOTA;
break;
+ case Opt_coherency_buffered:
+ mopt->mount_opt |= OCFS2_MOUNT_COHERENCY_BUFFERED;
+ break;
+ case Opt_coherency_full:
+ mopt->mount_opt &= ~OCFS2_MOUNT_COHERENCY_BUFFERED;
+ break;
case Opt_acl:
mopt->mount_opt |= OCFS2_MOUNT_POSIX_ACL;
mopt->mount_opt &= ~OCFS2_MOUNT_NO_POSIX_ACL;
@@ -1550,6 +1560,11 @@
if (opts & OCFS2_MOUNT_GRPQUOTA)
seq_printf(s, ",grpquota");
+ if (opts & OCFS2_MOUNT_COHERENCY_BUFFERED)
+ seq_printf(s, ",coherency=buffered");
+ else
+ seq_printf(s, ",coherency=full");
+
if (opts & OCFS2_MOUNT_NOUSERXATTR)
seq_printf(s, ",nouser_xattr");
else