cluster/afr: refactor

- Remove client side self-healing completely (opendir, openfd, lookup)
- Re-work readdir-failover to work reliably in case of NFS
- Remove unused/dead lock recovery code
- Consistently use xdata in both calls and callbacks in all FOPs
- Per-inode event generation, used to force inode ctx refresh
- Implement dirty flag support (in place of pending counts)
- Eliminate inode ctx structure, use read subvol bits + event_generation
- Implement inode ctx refreshing based on event generation
- Provide backward compatibility in transactions
- remove unused variables and functions
- make code more consistent in style and pattern
- regularize and clean up inode-write transaction code
- regularize and clean up dir-write transaction code
- regularize and clean up common FOPs
- reorganize transaction framework code
- skip setting xattrs in pending dict if nothing is pending
- re-write self-healing code using syncops
- re-write simpler self-heal-daemon

Change-Id: I1e4080c9796c8a2815c2dab4be3073f389d614a8
BUG: 1021686
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/6010
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 239 insertions, 0 deletions

diff --git a/xlators/cluster/afr/src/afr-read-txn.c b/xlators/cluster/afr/src/afr-read-txn.c
new file mode 100644
index 00000000000..186f68c3359
--- /dev/null
+++ b/xlators/cluster/afr/src/afr-read-txn.c
@@ -0,0 +1,239 @@
+/*
+  Copyright (c) 2013 Red Hat, Inc. <http://www.redhat.com>
+  This file is part of GlusterFS.
+
+  This file is licensed to you under your choice of the GNU Lesser
+  General Public License, version 3 or any later version (LGPLv3 or
+  later), or the GNU General Public License, version 2 (GPLv2), in all
+  cases as published by the Free Software Foundation.
+*/
+
+#include "afr.h"
+#include "afr-transaction.h"
+
+int
+afr_read_txn_next_subvol (call_frame_t *frame, xlator_t *this)
+{
+	afr_local_t *local = NULL;
+	afr_private_t *priv = NULL;
+	int i = 0;
+	int subvol = -1;
+
+	local = frame->local;
+	priv = this->private;
+
+
+	for (i = 0; i < priv->child_count; i++) {
+		if (!local->readable[i]) {
+			/* don't even bother trying here.
+			   just mark as attempted and move on. */
+			local->read_attempted[i] = 1;
+			continue;
+		}
+
+		if (!local->read_attempted[i]) {
+			subvol = i;
+			break;
+		}
+	}
+
+	/* If no more subvols were available for reading, we leave
+	   @subvol as -1, which is an indication we have run out of
+	   readable subvols. */
+	if (subvol != -1)
+		local->read_attempted[subvol] = 1;
+	local->readfn (frame, this, subvol);
+
+	return 0;
+}
+
+
+int
+afr_read_txn_refresh_done (call_frame_t *frame, xlator_t *this, int err)
+{
+	afr_local_t *local = NULL;
+	int read_subvol = 0;
+	int event_generation = 0;
+	inode_t *inode = NULL;
+	int ret = -1;
+
+	local = frame->local;
+	inode = local->inode;
+
+	if (err) {
+		local->op_errno = -err;
+		local->op_ret = -1;
+		read_subvol = -1;
+		goto readfn;
+	}
+
+	ret = afr_inode_read_subvol_type_get (inode, this, local->readable,
+					      &event_generation,
+					      local->transaction.type);
+
+	if (ret == -1 || !event_generation) {
+		/* Even after refresh, we don't have a good
+		   read subvolume. Time to bail */
+		local->op_ret = -1;
+		local->op_errno = EIO;
+		read_subvol = -1;
+		goto readfn;
+	}
+
+	read_subvol = afr_read_subvol_select_by_policy (inode, this,
+							local->readable);
+
+	if (read_subvol == -1) {
+		local->op_ret = -1;
+		local->op_errno = EIO;
+		goto readfn;
+	}
+
+	if (local->read_attempted[read_subvol]) {
+		afr_read_txn_next_subvol (frame, this);
+		return 0;
+	}
+
+	local->read_attempted[read_subvol] = 1;
+readfn:
+	local->readfn (frame, this, read_subvol);
+
+	return 0;
+}
+
+
+int
+afr_read_txn_continue (call_frame_t *frame, xlator_t *this, int subvol)
+{
+	afr_local_t *local = NULL;
+
+	local = frame->local;
+
+	if (!local->refreshed) {
+		local->refreshed = _gf_true;
+		afr_inode_refresh (frame, this, local->inode,
+				   afr_read_txn_refresh_done);
+	} else {
+		afr_read_txn_next_subvol (frame, this);
+	}
+
+	return 0;
+}
+
+
+/* afr_read_txn_wipe:
+
+   clean internal variables in @local in order to make
+   it possible to call afr_read_txn() multiple times from
+   the same frame
+*/
+
+void
+afr_read_txn_wipe (call_frame_t *frame, xlator_t *this)
+{
+	afr_local_t *local = NULL;
+	afr_private_t *priv = NULL;
+	int i = 0;
+
+	local = frame->local;
+	priv = this->private;
+
+	local->readfn = NULL;
+
+	if (local->inode)
+		inode_unref (local->inode);
+
+	for (i = 0; i < priv->child_count; i++) {
+		local->read_attempted[i] = 0;
+		local->readable[i] = 0;
+	}
+}
+
+
+/*
+  afr_read_txn:
+
+  This is the read transaction function. The way it works:
+
+  - Determine read-subvolume from inode ctx.
+
+  - If read-subvolume's generation was stale, refresh ctx once by
+    calling afr_inode_refresh()
+
+    Else make an attempt to read on read-subvolume.
+
+  - If attempted read on read-subvolume fails, refresh ctx once
+    by calling afr_inode_refresh()
+
+  - After ctx refresh, query read-subvolume freshly and attempt
+    read once.
+
+  - If read fails, try every other readable[] subvolume before
+    finally giving up. readable[] elements are set by afr_inode_refresh()
+    based on dirty and pending flags.
+
+  - If file is in split brain in the backend, generation will be
+    kept 0 by afr_inode_refresh() and readable[] will be set 0 for
+    all elements. Therefore reads always fail.
+*/
+
+int
+afr_read_txn (call_frame_t *frame, xlator_t *this, inode_t *inode,
+	      afr_read_txn_wind_t readfn, afr_transaction_type type)
+{
+	afr_local_t *local = NULL;
+	afr_private_t *priv = NULL;
+	int read_subvol = -1;
+	int event_generation = 0;
+	int ret = -1;
+
+	priv = this->private;
+	local = frame->local;
+
+	afr_read_txn_wipe (frame, this);
+
+	local->readfn = readfn;
+	local->inode = inode_ref (inode);
+
+	local->transaction.type = type;
+	ret = afr_inode_read_subvol_type_get (inode, this, local->readable,
+					      &event_generation, type);
+	if (ret == -1)
+		/* very first transaction on this inode */
+		goto refresh;
+
+	if (local->event_generation != event_generation)
+		/* servers have disconnected / reconnected, and possibly
+		   rebooted, very likely changing the state of freshness
+		   of copies */
+		goto refresh;
+
+	read_subvol = afr_read_subvol_select_by_policy (inode, this,
+							local->readable);
+
+	if (read_subvol < 0 || read_subvol > priv->child_count) {
+		gf_log (this->name, GF_LOG_WARNING, "Unreadable subvolume %d "
+			"found with event generation %d", read_subvol,
+			event_generation);
+		goto refresh;
+	}
+
+	if (!local->child_up[read_subvol]) {
+		/* should never happen, just in case */
+		gf_log (this->name, GF_LOG_WARNING, "subvolume %d is the "
+			"read subvolume in this generation, but is not up",
+			read_subvol);
+		goto refresh;
+	}
+
+	local->read_attempted[read_subvol] = 1;
+
+	local->readfn (frame, this, read_subvol);
+
+	return 0;
+
+refresh:
+	afr_inode_refresh (frame, this, inode, afr_read_txn_refresh_done);
+
+	return 0;
+}