Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Block pull request

# gpg: Signature made Thu 13 Mar 2014 13:50:49 GMT using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request: (24 commits)
  block/raw-win32: bdrv_parse_filename() for hdev
  block/raw-posix: Strip protocol prefix on creation
  block/raw-posix: bdrv_parse_filename() for cdrom
  block/raw-posix: bdrv_parse_filename() for floppy
  block/raw-posix: bdrv_parse_filename() for hdev
  qemu-io: Fix warnings from static code analysis
  block: Unlink temporary file
  qcow2: Don't write with BDRV_O_INCOMING
  qcow2: Keep option in qcow2_invalidate_cache()
  qmp: add query-iothreads command
  iothread: stash thread ID away
  dataplane: replace internal thread with IOThread
  iothread: add "iothread" qdev property type
  qdev: make get_pointer() handle temporary strings
  iothread: add I/O thread object
  aio: add aio_context_acquire() and aio_context_release()
  rfifolock: add recursive FIFO lock
  object: add object_get_canonical_path_component()
  block: Rewrite the snapshot authorization mechanism for block filters.
  iotests: Test corruption during COW request
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 22 insertions, 13 deletions

diff --git a/include/block/aio.h b/include/block/aio.h
index 2efdf416cf..a92511bd3b 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -19,6 +19,7 @@
 #include "qemu/queue.h"
 #include "qemu/event_notifier.h"
 #include "qemu/thread.h"
+#include "qemu/rfifolock.h"
 #include "qemu/timer.h"
 
 typedef struct BlockDriverAIOCB BlockDriverAIOCB;
@@ -47,6 +48,9 @@ typedef void IOHandler(void *opaque);
 struct AioContext {
     GSource source;
 
+    /* Protects all fields from multi-threaded access */
+    RFifoLock lock;
+
     /* The list of registered AIO handlers */
     QLIST_HEAD(, AioHandler) aio_handlers;
 
@@ -104,6 +108,20 @@ void aio_context_ref(AioContext *ctx);
  */
 void aio_context_unref(AioContext *ctx);
 
+/* Take ownership of the AioContext.  If the AioContext will be shared between
+ * threads, a thread must have ownership when calling aio_poll().
+ *
+ * Note that multiple threads calling aio_poll() means timers, BHs, and
+ * callbacks may be invoked from a different thread than they were registered
+ * from.  Therefore, code must use AioContext acquire/release or use
+ * fine-grained synchronization to protect shared state if other threads will
+ * be accessing it simultaneously.
+ */
+void aio_context_acquire(AioContext *ctx);
+
+/* Relinquish ownership of the AioContext. */
+void aio_context_release(AioContext *ctx);
+
 /**
  * aio_bh_new: Allocate a new bottom half structure.
  *
diff --git a/include/block/block.h b/include/block/block.h
index 780f48b7b3..bd34d14109 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -286,15 +286,6 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix);
 int bdrv_amend_options(BlockDriverState *bs_new, QEMUOptionParameter *options);
 
 /* external snapshots */
-
-typedef enum {
-    BS_IS_A_FILTER,
-    BS_FILTER_PASS_DOWN,
-    BS_AUTHORIZATION_COUNT,
-} BsAuthorization;
-
-bool bdrv_generic_is_first_non_filter(BlockDriverState *bs,
-                                      BlockDriverState *candidate);
 bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs,
                                       BlockDriverState *candidate);
 bool bdrv_is_first_non_filter(BlockDriverState *candidate);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 0bcf1c9b8c..4fc5ea8a65 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -76,10 +76,10 @@ struct BlockDriver {
     const char *format_name;
     int instance_size;
 
-    /* this table of boolean contains authorizations for the block operations */
-    bool authorizations[BS_AUTHORIZATION_COUNT];
-    /* for snapshots complex block filter like Quorum can implement the
-     * following recursive callback instead of BS_IS_A_FILTER.
+    /* set to true if the BlockDriver is a block filter */
+    bool is_filter;
+    /* for snapshots block filter like Quorum can implement the
+     * following recursive callback.
      * It's purpose is to recurse on the filter children while calling
      * bdrv_recurse_is_first_non_filter on them.
      * For a sample implementation look in the future Quorum block filter.