From ffe4f32d741439547577bc87e1f08df8f6f2a151 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 15 Mar 2019 18:10:08 +0100
Subject: [PATCH 012/163] file-posix: Lock new fd in raw_reopen_prepare()

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20190315181010.14964-13-kwolf@redhat.com>
Patchwork-id: 84889
O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 12/14] file-posix: Lock new fd in raw_reopen_prepare()
Bugzilla: 1685989
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

There is no reason why we can take locks on the new file descriptor only
in raw_reopen_commit() where error handling isn't possible any more.
Instead, we can already do this in raw_reopen_prepare().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit a6aeca0ca530f104b5a5dd6704fca22b2c5edefa)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/file-posix.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index b577d88..ae16f2f 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -897,7 +897,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,
 {
     BDRVRawState *s;
     BDRVRawReopenState *rs;
-    int ret = 0;
+    int ret;
     Error *local_err = NULL;
 
     assert(state != NULL);
@@ -921,14 +921,27 @@ static int raw_reopen_prepare(BDRVReopenState *state,
     if (rs->fd != -1) {
         raw_probe_alignment(state->bs, rs->fd, &local_err);
         if (local_err) {
-            qemu_close(rs->fd);
-            rs->fd = -1;
             error_propagate(errp, local_err);
             ret = -EINVAL;
+            goto out_fd;
+        }
+
+        /* Copy locks to the new fd */
+        ret = raw_apply_lock_bytes(NULL, rs->fd, s->locked_perm,
+                                   s->locked_shared_perm, false, errp);
+        if (ret < 0) {
+            ret = -EINVAL;
+            goto out_fd;
         }
     }
 
     s->reopen_state = state;
+    ret = 0;
+out_fd:
+    if (ret < 0) {
+        qemu_close(rs->fd);
+        rs->fd = -1;
+    }
 out:
     return ret;
 }
@@ -937,17 +950,9 @@ static void raw_reopen_commit(BDRVReopenState *state)
 {
     BDRVRawReopenState *rs = state->opaque;
     BDRVRawState *s = state->bs->opaque;
-    Error *local_err = NULL;
 
     s->open_flags = rs->open_flags;
 
-    /* Copy locks to the new fd before closing the old one. */
-    raw_apply_lock_bytes(NULL, rs->fd, s->locked_perm,
-                         s->locked_shared_perm, false, &local_err);
-    if (local_err) {
-        /* shouldn't fail in a sane host, but report it just in case. */
-        error_report_err(local_err);
-    }
     qemu_close(s->fd);
     s->fd = rs->fd;
 
-- 
1.8.3.1