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>

2 files changed, 136 insertions, 0 deletions

diff --git a/xlators/protocol/client/src/client-rpc-fops.c b/xlators/protocol/client/src/client-rpc-fops.c
index 53cf3968a..c05542834 100644
--- a/xlators/protocol/client/src/client-rpc-fops.c
+++ b/xlators/protocol/client/src/client-rpc-fops.c
@@ -1993,6 +1993,61 @@ out:
 }
 
 int
+client3_3_discard_cbk(struct rpc_req *req, struct iovec *iov, int count,
+		      void *myframe)
+{
+        call_frame_t    *frame      = NULL;
+        gfs3_discard_rsp rsp      = {0,};
+        struct iatt      prestat    = {0,};
+        struct iatt      poststat   = {0,};
+        int              ret        = 0;
+        xlator_t *this       = NULL;
+        dict_t  *xdata       = NULL;
+
+        this = THIS;
+
+        frame = myframe;
+
+        if (-1 == req->rpc_status) {
+                rsp.op_ret   = -1;
+                rsp.op_errno = ENOTCONN;
+                goto out;
+        }
+        ret = xdr_to_generic(*iov, &rsp, (xdrproc_t) xdr_gfs3_discard_rsp);
+        if (ret < 0) {
+                gf_log (this->name, GF_LOG_ERROR, "XDR decoding failed");
+                rsp.op_ret   = -1;
+                rsp.op_errno = EINVAL;
+                goto out;
+        }
+
+        if (-1 != rsp.op_ret) {
+                gf_stat_to_iatt (&rsp.statpre, &prestat);
+                gf_stat_to_iatt (&rsp.statpost, &poststat);
+        }
+
+        GF_PROTOCOL_DICT_UNSERIALIZE (this, xdata, (rsp.xdata.xdata_val),
+                                      (rsp.xdata.xdata_len), ret,
+                                      rsp.op_errno, out);
+
+out:
+        if (rsp.op_ret == -1) {
+                gf_log (this->name, GF_LOG_WARNING, "remote operation failed: %s",
+                        strerror (gf_error_to_errno (rsp.op_errno)));
+        }
+        CLIENT_STACK_UNWIND (discard, frame, rsp.op_ret,
+                             gf_error_to_errno (rsp.op_errno), &prestat,
+                             &poststat, xdata);
+
+        free (rsp.xdata.xdata_val);
+
+        if (xdata)
+                dict_unref (xdata);
+
+        return 0;
+}
+
+int
 client3_3_setattr_cbk (struct rpc_req *req, struct iovec *iov, int count,
                        void *myframe)
 {
@@ -5888,6 +5943,50 @@ unwind:
         return 0;
 }
 
+int32_t
+client3_3_discard(call_frame_t *frame, xlator_t *this, void *data)
+{
+        clnt_args_t       *args     = NULL;
+        int64_t            remote_fd = -1;
+        clnt_conf_t       *conf     = NULL;
+	gfs3_discard_req   req	    = {{0},};
+        int                op_errno = ESTALE;
+        int                ret        = 0;
+
+        if (!frame || !this || !data)
+                goto unwind;
+
+        args = data;
+        conf = this->private;
+
+        CLIENT_GET_REMOTE_FD (this, args->fd, DEFAULT_REMOTE_FD,
+                              remote_fd, op_errno, unwind);
+
+        req.fd = remote_fd;
+	req.offset = args->offset;
+	req.size = args->size;
+	memcpy(req.gfid, args->fd->inode->gfid, 16);
+
+        GF_PROTOCOL_DICT_SERIALIZE (this, args->xdata, (&req.xdata.xdata_val),
+                                    req.xdata.xdata_len, op_errno, unwind);
+
+        ret = client_submit_request(this, &req, frame, conf->fops,
+                                    GFS3_OP_DISCARD, client3_3_discard_cbk,
+				    NULL, NULL, 0, NULL, 0, NULL,
+                                    (xdrproc_t) xdr_gfs3_discard_req);
+        if (ret)
+                gf_log (this->name, GF_LOG_WARNING, "failed to send the fop");
+
+        GF_FREE (req.xdata.xdata_val);
+
+        return 0;
+unwind:
+        CLIENT_STACK_UNWIND(discard, frame, -1, op_errno, NULL, NULL, NULL);
+        GF_FREE (req.xdata.xdata_val);
+
+        return 0;
+}
+
 /* Table Specific to FOPS */
 
 
@@ -5934,6 +6033,7 @@ rpc_clnt_procedure_t clnt3_3_fop_actors[GF_FOP_MAXVALUE] = {
         [GF_FOP_FSETATTR]    = { "FSETATTR",    client3_3_fsetattr },
         [GF_FOP_READDIRP]    = { "READDIRP",    client3_3_readdirp },
 	[GF_FOP_FALLOCATE]   = { "FALLOCATE",	client3_3_fallocate },
+	[GF_FOP_DISCARD]     = { "DISCARD",	client3_3_discard },
         [GF_FOP_RELEASE]     = { "RELEASE",     client3_3_release },
         [GF_FOP_RELEASEDIR]  = { "RELEASEDIR",  client3_3_releasedir },
         [GF_FOP_GETSPEC]     = { "GETSPEC",     client3_getspec },
@@ -5984,6 +6084,7 @@ char *clnt3_3_fop_names[GFS3_OP_MAXVALUE] = {
         [GFS3_OP_FSETATTR]    = "FSETATTR",
         [GFS3_OP_READDIRP]    = "READDIRP",
 	[GFS3_OP_FALLOCATE]   = "FALLOCATE",
+	[GFS3_OP_DISCARD]     = "DISCARD",
         [GFS3_OP_RELEASE]     = "RELEASE",
         [GFS3_OP_RELEASEDIR]  = "RELEASEDIR",
         [GFS3_OP_FREMOVEXATTR] = "FREMOVEXATTR",
diff --git a/xlators/protocol/client/src/client.c b/xlators/protocol/client/src/client.c
index 377263af6..aa2b8eef8 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,
 };