On Tue, May 11, 2010 at 2:23 AM, Bruce Guenter <bruce@xxxxxxxxxxxxxx> wrote: > Hi. > > When deleting a snapshot, I have observed that the disk space used by > that snapshot is not immediately released (according to statvfs or df). > Neither "sync" nor "btrfs filesystem sync" releases the disk space > neither. The only way I have found to actually fully release the disk > space is to issue the sync and then sleep until the statvfs free numbers > stop changing. > > This is a rather problematic approach to managing disk space. Is there > any way to either force a wait until the disk space has been released? > > My application is automatically managing disk space in the presence of > snapshots. I allow the disk (a backup) to fill up with snapshots until > it is nearly full, and then to delete snapshots until I have a threshold > free. However, without the disk space being released promptly and no > way to wait until it is released, the loop can't tell how many snapshots > to delete. > This is because the snapshot deleting ioctl only removes the a link. The corresponding tree is dropped in the background by a kernel thread. We could probably add another ioctl that waits until the tree has been completely dropped. Yan, Zheng -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
