On 04/22/2017 06:45 PM, Chris Murphy wrote: > On Fri, Apr 21, 2017 at 4:26 AM, Hans van Kranenburg > <hans.van.kranenb...@mendix.com> wrote: > >> >> == Thinking out of the box == >> >> Technically, converting from DUP to single could also mean: >> * Flipping one bit in the block group type flags to 0 for each block >> group item >> * Flipping one bit in the chunk type flags and removing 1 stripe struct >> for each metadata chunk item >> * Removing the >> * Anything else? > > [...] > Such a prune would > need to write out new chunk and dev trees, and then whatever nodes end > up pointing to those, maybe it's just the super blocks.
Or just use the existing offline tree plumbing code to remove some items and insert some replacement ones. >> How feasible would it be to write btrfs-progs style conversion to do this? > > I can pretty much say it's not just a bit flip change because at the > very least you've got new CRCs to write for any changed node. The tree plumbing will take care of that, I was not planning to hexedit it. > [...] I was actually thinking about writing a C extension for python-btrfs that gives me access to the building blocks that are present inside the btrfs-progs code, so that the 'heavy lifting' can be done there, and so that I can just easily script opening a filesystem and then doing tree changes, inserting and removing some tree items, even interactively. ;-) -- Hans van Kranenburg -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
