On 03/08/16 22:55, Graham Cobb wrote: > On 03/08/16 21:37, Adam Borowski wrote: >> On Wed, Aug 03, 2016 at 08:56:01PM +0100, Graham Cobb wrote: >>> Are there any btrfs commands (or APIs) to allow a script to create a >>> list of all the extents referred to within a particular (mounted) >>> subvolume? And is it a reasonably efficient process (i.e. doesn't >>> involve backrefs and, preferably, doesn't involve following directory >>> trees)? In case anyone else is interested in this, I ended up creating some simple scripts to allow me to do this. They are slow because they walk the directory tree and they use filefrag to get the extent data, but they do let me answer questions like: * How much space am I wasting by keeping historical snapshots? * How much data is being shared between two subvolumes * How much of the data in my latest snapshot is unique to that snapshot? * How much data would I actually free up if I removed (just) these particular subvolumes? If they are useful to anyone else you can find them at: https://github.com/GrahamCobb/extents-lists If anyone knows of more efficient ways to get this information please let me know. And, of course, feel free to suggest improvements/bugfixes! -- 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
