glusterfs: discard (hole punch) support

Add support for the DISCARD file operation. Discard punches a hole
in a file in the provided range. Block de-allocation is implemented
via fallocate() (as requested via fuse and passed on to the brick
fs) but a separate fop is created within gluster to emphasize the
fact that discard changes file data (the discarded region is
replaced with zeroes) and must invalidate caches where appropriate.

BUG: 963678
Change-Id: I34633a0bfff2187afeab4292a15f3cc9adf261af
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.org/5090
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/xlators/protocol/client/src/client.c b/xlators/protocol/client/src/client.c
index 377263af64a..aa2b8eef8e5 100644
--- a/xlators/protocol/client/src/client.c
+++ b/xlators/protocol/client/src/client.c
@@ -1997,6 +1997,40 @@ out:
 }
 
 int32_t
+client_discard(call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
+	       size_t len, dict_t *xdata)
+{
+        int          ret  = -1;
+        clnt_conf_t *conf = NULL;
+        rpc_clnt_procedure_t *proc = NULL;
+        clnt_args_t  args = {0,};
+
+        conf = this->private;
+        if (!conf || !conf->fops)
+                goto out;
+
+        args.fd = fd;
+	args.offset = offset;
+	args.size = len;
+        args.xdata = xdata;
+
+        proc = &conf->fops->proctable[GF_FOP_DISCARD];
+        if (!proc) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "rpc procedure not found for %s",
+                        gf_fop_list[GF_FOP_DISCARD]);
+                goto out;
+        }
+        if (proc->fn)
+                ret = proc->fn (frame, this, &args);
+out:
+        if (ret)
+                STACK_UNWIND_STRICT(discard, frame, -1, ENOTCONN, NULL, NULL, NULL);
+
+	return 0;
+}
+
+int32_t
 client_getspec (call_frame_t *frame, xlator_t *this, const char *key,
                 int32_t flags)
 {
@@ -2714,6 +2748,7 @@ struct xlator_fops fops = {
         .setattr     = client_setattr,
         .fsetattr    = client_fsetattr,
 	.fallocate   = client_fallocate,
+	.discard     = client_discard,
         .getspec     = client_getspec,
 };