Mailing List Archive

# HG changeset patch
# User sos22@douglas.cl.cam.ac.uk
# Node ID 265f68795ebf254cc07b8cc17e8d5813b7df5c0c
# Parent d4ab8e46136ccb64a75dbdb6e84126d6a9552ca4
Avoid a hang when probing the partition table on imported block
devices. If you export a device so the importing domain sees it as a
whole disk rather than a partition, then add_disk will try to probe
its partition table. However, we were calling add_disk before the
device was properly connected, and then not connecting it until
add_disk had finished. This meant that we ended up never actually
connecting the device, and any accesses to it would then hang.

Fix this by not calling add_disk until we're connected.

Signed-off-by: Steven Smith, sos22@cam.ac.uk

diff -r d4ab8e46136c -r 265f68795ebf linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c Fri Dec 2 12:27:39 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c Fri Dec 2 14:16:37 2005
@@ -311,7 +311,7 @@
int err;

if( (info->connected == BLKIF_STATE_CONNECTED) ||
- (info->connected == BLKIF_STATE_SUSPENDED) )
+ (info->connected == BLKIF_STATE_SUSPENDED) )
return;

DPRINTK("blkfront.c:connect:%s.\n", info->xbdev->otherend);
@@ -327,16 +327,18 @@
info->xbdev->otherend);
return;
}
-
+
xlvbd_add(sectors, info->vdevice, binfo, sector_size, info);

(void)xenbus_switch_state(info->xbdev, NULL, XenbusStateConnected);
-
+
/* Kick pending requests. */
spin_lock_irq(&blkif_io_lock);
info->connected = BLKIF_STATE_CONNECTED;
kick_pending_request_queues(info);
spin_unlock_irq(&blkif_io_lock);
+
+ add_disk(info->gd);
}

/**
@@ -588,7 +590,6 @@

while ((req = elv_next_request(rq)) != NULL) {
info = req->rq_disk->private_data;
-
if (!blk_fs_request(req)) {
end_request(req, 0);
continue;
diff -r d4ab8e46136c -r 265f68795ebf linux-2.6-xen-sparse/drivers/xen/blkfront/block.h
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/block.h Fri Dec 2 12:27:39 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/block.h Fri Dec 2 14:16:37 2005
@@ -146,6 +146,9 @@
extern void do_blkif_request (request_queue_t *rq);

/* Virtual block-device subsystem. */
+/* Note that xlvbd_add doesn't call add_disk for you: you're expected
+ to call add_disk on info->gd once the disk is properly connected
+ up. */
int xlvbd_add(blkif_sector_t capacity, int device,
u16 vdisk_info, u16 sector_size, struct blkfront_info *info);
void xlvbd_del(struct blkfront_info *info);
diff -r d4ab8e46136c -r 265f68795ebf linux-2.6-xen-sparse/drivers/xen/blkfront/vbd.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/vbd.c Fri Dec 2 12:27:39 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/vbd.c Fri Dec 2 14:16:37 2005
@@ -261,7 +261,6 @@
if (vdisk_info & VDISK_CDROM)
gd->flags |= GENHD_FL_CD;

- add_disk(gd);
info->gd = gd;

return 0;

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