block: add eject request callback

Recent versions of udev always keep the tray locked so that the kernel
can observe "eject request" events (aka tray button presses) even on
discs that aren't mounted.  Add support for these events in the ATAPI
and SCSI cd drive device models.

To let management cope with the behavior of udev, an event should also
be added for "tray opened/closed".  This way, after issuing an "eject"
command, management can poll until the guests actually reacts to the
command.  They can then issue the "change" command after the tray has been
opened, or try with "eject -f" after a (configurable?) timeout.  However,
with this patch and the corresponding support in the device models,
at least it is possible to do a manual two-step eject+change sequence.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block.c b/block.c
index 9bb236c98940f7f4d294c52ded605f1972062759..5c30c9dd68ce917f90d27279f9df477a0b3e6660 100644 (file)
--- a/block.c
+++ b/block.c
@@ -816,6 +816,13 @@ bool bdrv_dev_has_removable_media(BlockDriverState *bs)
     return !bs->dev || (bs->dev_ops && bs->dev_ops->change_media_cb);
 }
 
+void bdrv_dev_eject_request(BlockDriverState *bs, bool force)
+{
+    if (bs->dev_ops && bs->dev_ops->eject_request_cb) {
+        bs->dev_ops->eject_request_cb(bs->dev_opaque, force);
+    }
+}
+
 bool bdrv_dev_is_tray_open(BlockDriverState *bs)
 {
     if (bs->dev_ops && bs->dev_ops->is_tray_open) {

diff --git a/block.h b/block.h
index 38cd748b606ad61f7605bf5269ffcb3e3bf966a7..051a25d8d63d141cc7c2ce5e3092dc1c6c7c7e3a 100644 (file)
--- a/block.h
+++ b/block.h
@@ -38,6 +38,15 @@ typedef struct BlockDevOps {
      * Device models with removable media must implement this callback.
      */
     void (*change_media_cb)(void *opaque, bool load);
+    /*
+     * Runs when an eject request is issued from the monitor, the tray
+     * is closed, and the medium is locked.
+     * Device models that do not implement is_medium_locked will not need
+     * this callback.  Device models that can lock the medium or tray might
+     * want to implement the callback and unlock the tray when "force" is
+     * true, even if they do not support eject requests.
+     */
+    void (*eject_request_cb)(void *opaque, bool force);
     /*
      * Is the virtual tray open?
      * Device models implement this only when the device has a tray.
@@ -111,6 +120,7 @@ void bdrv_detach_dev(BlockDriverState *bs, void *dev);
 void *bdrv_get_attached_dev(BlockDriverState *bs);
 void bdrv_set_dev_ops(BlockDriverState *bs, const BlockDevOps *ops,
                       void *opaque);
+void bdrv_dev_eject_request(BlockDriverState *bs, bool force);
 bool bdrv_dev_has_removable_media(BlockDriverState *bs);
 bool bdrv_dev_is_tray_open(BlockDriverState *bs);
 bool bdrv_dev_is_medium_locked(BlockDriverState *bs);

diff --git a/blockdev.c b/blockdev.c
index 0827bf77438a7d245b1f308c52ef809f9535c2ca..222818690daa0279885b0e18a477f0d58ed9da97 100644 (file)
--- a/blockdev.c
+++ b/blockdev.c
@@ -635,10 +635,12 @@ static int eject_device(Monitor *mon, BlockDriverState *bs, int force)
         qerror_report(QERR_DEVICE_NOT_REMOVABLE, bdrv_get_device_name(bs));
         return -1;
     }
-    if (!force && !bdrv_dev_is_tray_open(bs)
-        && bdrv_dev_is_medium_locked(bs)) {
-        qerror_report(QERR_DEVICE_LOCKED, bdrv_get_device_name(bs));
-        return -1;
+    if (bdrv_dev_is_medium_locked(bs) && !bdrv_dev_is_tray_open(bs)) {
+        bdrv_dev_eject_request(bs, force);
+        if (!force) {
+            qerror_report(QERR_DEVICE_LOCKED, bdrv_get_device_name(bs));
+            return -1;
+        }
     }
     bdrv_close(bs);
     return 0;