[Qemu-devel] [PATCH] ide: Add resize callback to ide/core

[John Snow <jsnow@redhat.com>]

Currently, if the block device backing the IDE drive is resized,
the information about the device as cached inside of the IDEState
structure is not updated, thus when a guest OS re-queries the drive,
it is unable to see the expanded size.

This patch adds a resize callback to correct this, and marks the
identify buffer cache as being dirty to force ide_identify to
regenerate this information. This callback also attempts to update
the legacy CHS values, if only to maintain a sense of
informational consistency.

Lastly, a Linux guest as-is cannot resize a libata drive while in-use,
but it can see the expanded size as part of a bus rescan event.
This patch also allows guests such as Linux to see the new drive size
after a soft reboot event, without having to exit the QEMU process.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 hw/ide/core.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index db191a6..6c86e21 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2099,6 +2099,30 @@ static bool ide_cd_is_medium_locked(void *opaque)
     return ((IDEState *)opaque)->tray_locked;
 }
 
+static void ide_resize_cb(void *opaque)
+{
+    IDEState *s = opaque;
+    IDEDevice *dev = s->unit ? s->bus->slave : s->bus->master;
+    uint64_t nb_sectors;
+
+    /* Convince blkconf_geometry to re-determine geometry */
+    dev->conf.cyls = 0;
+    dev->conf.heads = 0;
+    dev->conf.secs = 0;
+
+    blkconf_geometry(&dev->conf, &dev->chs_trans, 65536, 16, 255);
+    bdrv_get_geometry(s->bs, &nb_sectors);
+
+    s->nb_sectors = nb_sectors;
+    s->cylinders = dev->conf.cyls;
+    s->heads = dev->conf.heads;
+    s->sectors = dev->conf.secs;
+    s->chs_trans = dev->chs_trans;
+
+    /* Let ide_identify() know it needs to regenerate the response. */
+    s->identify_set = 0;
+}
+
 static const BlockDevOps ide_cd_block_ops = {
     .change_media_cb = ide_cd_change_cb,
     .eject_request_cb = ide_cd_eject_request_cb,
@@ -2106,6 +2130,10 @@ static const BlockDevOps ide_cd_block_ops = {
     .is_medium_locked = ide_cd_is_medium_locked,
 };
 
+static const BlockDevOps ide_hd_block_ops = {
+    .resize_cb = ide_resize_cb,
+};
+
 int ide_init_drive(IDEState *s, BlockDriverState *bs, IDEDriveKind kind,
                    const char *version, const char *serial, const char *model,
                    uint64_t wwn,
@@ -2142,6 +2170,7 @@ int ide_init_drive(IDEState *s, BlockDriverState *bs, IDEDriveKind kind,
             error_report("Can't use a read-only drive");
             return -1;
         }
+        bdrv_set_dev_ops(bs, &ide_hd_block_ops, s);
     }
     if (serial) {
         pstrcpy(s->drive_serial_str, sizeof(s->drive_serial_str), serial);
-- 
1.9.3