cluster/ec: fix fd reopen

Currently EC tries to reopen fd's that have been opened while a brick
was down. This is done as part of regular write operations, just after
having acquired the locks, and it's sent as a sub-fop of the main write
fop.

There were two problems:

1. The reopen was attempted on all UP bricks, even if a previous lock
didn't succeed. This is incorrect because most probably the open will
fail.

2. If reopen is sent and fails, the error is propagated to the main
operation, causing it to fail when it shouldn't.

To fix this, we only attempt reopens on bricks where the current fop
owns a lock, and we prevent any error to be propagated to the main
fop.

To implement this behaviour an argument used to indicate the minimum
number of required answers has overloaded to also include some flags. To
make the change consistent, it has been necessary to rename the
argument, which means that a lot of files have been changed. However
there are no functional changes.

This change has also uncovered a problem in discard code, which didn't
correctely process requests of small sizes because no real discard fop
was being processed, only a write of 0's on some region. In this case
some fields of the fop remained uninitialized or with incorrect values.
To fix this, a new function has been created to simulate success on a
fop and it's used in the discard case.

Thanks to Pranith for providing a test script that has also detected an
issue in this patch. This patch includes a small modification of this
script to force data to be written into bricks before stopping them.

Backport of:
> Change-Id: If272343873369186c2fb8f43c1d9c52c3ea304ec
> BUG: bz#1699866
> Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

Change-Id: If272343873369186c2fb8f43c1d9c52c3ea304ec
Fixes: bz#1699917
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/tests/bugs/ec/bug-1699866-check-reopen-fd.t b/tests/bugs/ec/bug-1699866-check-reopen-fd.t
new file mode 100644
index 00000000000..4386d010318
--- /dev/null
+++ b/tests/bugs/ec/bug-1699866-check-reopen-fd.t
@@ -0,0 +1,34 @@
+#!/bin/bash
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+. $(dirname $0)/../../fileio.rc
+
+cleanup
+
+TEST glusterd
+TEST pidof glusterd
+TEST $CLI volume create $V0 disperse 6 redundancy 2 $H0:$B0/${V0}{0..5}
+TEST $CLI volume heal $V0 disable
+TEST $CLI volume set $V0 disperse.background-heals 0
+TEST $CLI volume set $V0 write-behind off
+TEST $CLI volume set $V0 open-behind off
+TEST $CLI volume start $V0
+TEST glusterfs --entry-timeout=0 --attribute-timeout=0 -s $H0 --volfile-id $V0 $M0
+EXPECT_WITHIN $CHILD_UP_TIMEOUT "6" ec_child_up_count $V0 0
+
+TEST mkdir -p $M0/dir
+
+fd="$(fd_available)"
+
+TEST kill_brick $V0 $H0 $B0/${V0}0
+EXPECT_WITHIN $CHILD_UP_TIMEOUT "5" ec_child_up_count $V0 0
+
+TEST fd_open ${fd} rw $M0/dir/test
+TEST fd_write ${fd} "test1"
+TEST $CLI volume replace-brick ${V0} $H0:$B0/${V0}0 $H0:$B0/${V0}0_1 commit force
+EXPECT_WITHIN $CHILD_UP_TIMEOUT "6" ec_child_up_count $V0 0
+TEST fd_write ${fd} "test2"
+TEST fd_close ${fd}
+
+cleanup