cluster/ec: Prevent double pre-op xattrops

Problem:
Race:
Thread-1                                    Thread-2
1) Does ec_get_size_version() to perform
pre-op fxattrop as part of write-1
                                           2) Calls ec_set_dirty_flag() in
                                              ec_get_size_version() for write-2.
					      This sets dirty[] to 1
3) Completes executing
ec_prepare_update_cbk leading to
ctx->dirty[] = '1'
					   4) Takes LOCK(inode->lock) to check if there are
					      any flags and sets dirty-flag because
				              lock->waiting_flag is 0 now. This leads to
					      fxattrop to increment on-disk dirty[] to '2'

At the end of the writes the file will be marked for heal even when it doesn't need heal.

Fix:
Perform ec_set_dirty_flag() and other checks inside LOCK() to prevent dirty[] to be marked
as '1' in step 2) above

Fixes: bz#1805050
Change-Id: Icac2ab39c0b1e7e154387800fbededc561612865
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/basic/ec/ec-dirty-flags.t b/tests/basic/ec/ec-dirty-flags.t
new file mode 100644
index 00000000000..68e66103f08
--- /dev/null
+++ b/tests/basic/ec/ec-dirty-flags.t
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+
+# This checks if the fop keeps the dirty flags settings correctly after
+# finishing the fop.
+
+cleanup
+TEST glusterd
+TEST pidof glusterd
+TEST $CLI volume create $V0 disperse 3 redundancy 1 $H0:$B0/${V0}{0..2}
+TEST $CLI volume heal $V0 disable
+TEST $CLI volume start $V0
+
+TEST $GFS --volfile-id=/$V0 --volfile-server=$H0 $M0;
+EXPECT_WITHIN $CHILD_UP_TIMEOUT "3" ec_child_up_count $V0 0
+cd $M0
+for i in {1..1000}; do dd if=/dev/zero of=file-${i} bs=512k count=2; done
+cd -
+EXPECT "^0$" get_pending_heal_count $V0
+
+cleanup