Oh, didn't know that XFS is going to have many of Btrfs features and continues to evolve. Thank you for the answer. 22.08.2016, 23:14, "Jeff Mahoney" <jeffm@xxxxxxxx>: > On 8/21/16 2:59 PM, Tomokhov Alexander wrote: >> Btrfs wiki FAQ gives a link to example Python script: https://github.com/stsquad/scripts/blob/master/uncow.py >> >> But such a crucial and fundamental tool must exist in stock btrfs-progs. Filesystem with CoW technology at it's core must provide user sufficient control over CoW aspects. Running 3rd-party or manually written scripts for filesystem properties/metadata manipulation is not convenient, not safe and definitely not the way it must be done. >> >> Also is it possible (at least in theory) to "uncow" files being currently opened in-place? Without the trickery with creation & renaming of files or directories. So that running "chattr +C" on a file would be sufficient. If possible, is it going to be implemented? > > XFS is looking to do this via fallocate using a flag that all file > systems can choose to honor. Once that lands, it would make sense for > btrfs to use it as well. The idea is that when you pass the flag in, we > examine the range and CoW anything that has a refcount != 1. > > That code hasn't landed yet though. The last time I saw it posted was > June. I don't speak with knowledge of the integration plan, but it > might just be queued up for the next merge window now that the reverse > mapping patches have landed in 4.8. > > -Jeff > > -- > Jeff Mahoney > SUSE Labs -- 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
