From: Alex Elder Date: Wed, 8 Feb 2012 22:11:14 +0000 (-0600) Subject: rbd: don't drop the rbd_id too early X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=32eec68d2f233e8a6ae1cd326022f6862e2b9ce3;p=linux-beck.git rbd: don't drop the rbd_id too early Currently an rbd device's id is released when it is removed, but it is done before the code is run to clean up sysfs-related files (such as /sys/bus/rbd/devices/1). It's possible that an rbd is still in use after the rbd_remove() call has been made. It's essentially the same as an active inode that stays around after it has been removed--until its final close operation. This means that the id shows up as free for reuse at a time it should not be. The effect of this was seen by Jens Rehpoehler, who: - had a filesystem mounted on an rbd device - unmapped that filesystem (without unmounting) - found that the mount still worked properly - but hit a panic when he attempted to re-map a new rbd device This re-map attempt found the previously-unmapped id available. The subsequent attempt to reuse it was met with a panic while attempting to (re-)install the sysfs entry for the new mapped device. Fix this by holding off "putting" the rbd id, until the rbd_device release function is called--when the last reference is finally dropped. Note: This fixes: http://tracker.newdream.net/issues/1907 Signed-off-by: Alex Elder Signed-off-by: Sage Weil --- diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 568fa5b1206b..6bbd5af1f029 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -2421,7 +2421,12 @@ static ssize_t rbd_add(struct bus_type *bus, if (rc) goto err_out_blkdev; - /* set up and announce blkdev mapping */ + /* + * At this point cleanup in the event of an error is the job + * of the sysfs code (initiated by rbd_bus_del_dev()). + * + * Set up and announce blkdev mapping. + */ rc = rbd_init_disk(rbd_dev); if (rc) goto err_out_bus; @@ -2433,8 +2438,6 @@ static ssize_t rbd_add(struct bus_type *bus, return count; err_out_bus: - rbd_id_put(rbd_dev); - /* this will also clean up rest of rbd_dev stuff */ rbd_bus_del_dev(rbd_dev); @@ -2492,6 +2495,9 @@ static void rbd_dev_release(struct device *dev) /* clean up and free blkdev */ rbd_free_disk(rbd_dev); unregister_blkdev(rbd_dev->major, rbd_dev->name); + + /* done with the id, and with the rbd_dev */ + rbd_id_put(rbd_dev); kfree(rbd_dev); /* release module ref */ @@ -2524,8 +2530,6 @@ static ssize_t rbd_remove(struct bus_type *bus, goto done; } - rbd_id_put(rbd_dev); - __rbd_remove_all_snaps(rbd_dev); rbd_bus_del_dev(rbd_dev);