[Qemu-devel] [PATCH 1/1] block/file-posix.c: fix not reopened lock file descriptor

[Dion Bosschieter <dionbosschieter@gmail.com>]

In commit 244a5668106297378391b768e7288eb157616f64 another
file descriptor to BDRVRawState is added. When we try to issue the
reopen command only s->fd is reopened; lock_fd could still hold an old
file descriptor "possibly" pointing to another file.

- change raw_reopen_prepare so it checks use_lock from BDRVRawState and
tries to reopen lock_fd accordingly
- change raw_reopen_commit so it closes the old lock_fd on use_lock

Signed-off-by: Dion Bosschieter <dionbosschieter@gmail.com>
---
 block/file-posix.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/block/file-posix.c b/block/file-posix.c
index d7fb772c14..16d83fc49e 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -167,6 +167,7 @@ typedef struct BDRVRawState {
 
 typedef struct BDRVRawReopenState {
     int fd;
+    int lock_fd;
     int open_flags;
 } BDRVRawReopenState;
 
@@ -795,6 +796,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,
     raw_parse_flags(state->flags, &rs->open_flags);
 
     rs->fd = -1;
+    rs->lock_fd = -1;
 
     int fcntl_flags = O_APPEND | O_NONBLOCK;
 #ifdef O_NOATIME
@@ -820,6 +822,17 @@ static int raw_reopen_prepare(BDRVReopenState *state,
                 rs->fd = -1;
             }
         }
+
+        if (s->use_lock) {
+            rs->lock_fd = qemu_dup(s->lock_fd);
+            if (rs->lock_fd >= 0) {
+                ret = fcntl_setfl(rs->lock_fd, rs->open_flags);
+                if (ret) {
+                    qemu_close(rs->lock_fd);
+                    rs->lock_fd = -1;
+                }
+            }
+        }
     }
 
     /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
@@ -835,6 +848,14 @@ static int raw_reopen_prepare(BDRVReopenState *state,
                 error_setg_errno(errp, errno, "Could not reopen file");
                 ret = -1;
             }
+
+            if (s->use_lock) {
+                rs->lock_fd = qemu_open(normalized_filename, rs->open_flags);
+                if (rs->lock_fd == -1) {
+                    error_setg_errno(errp, errno, "Could not reopen file for locking");
+                    ret = -1;
+                }
+            }
         }
     }
 
@@ -861,7 +882,11 @@ static void raw_reopen_commit(BDRVReopenState *state)
     s->open_flags = rs->open_flags;
 
     qemu_close(s->fd);
+    if (s->use_lock) {
+        qemu_close(s->lock_fd);
+    }
     s->fd = rs->fd;
+    s->lock_fd = rs->lock_fd;
 
     g_free(state->opaque);
     state->opaque = NULL;
-- 
2.14.2