On Fri, Apr 26, 2024 at 11:54:29AM +0100, Giovanni Cabiddu wrote: > From: Weigang Li <weigang.li@xxxxxxxxx> > > Add support for zlib compression and decompression through the acomp > APIs. > Input pages are added to an sg-list and sent to acomp in one request. > Since acomp is asynchronous, the thread is put to sleep and then the CPU > is freed up. Once compression is done, the acomp callback is triggered > and the thread is woke up. > > This patch doesn't change the BTRFS disk format, this means that files > compressed by hardware engines can be de-compressed by the zlib software > library, and vice versa. > > Limitations: > * The implementation tries always to use an acomp even if only > zlib-deflate-scomp is present > * Acomp does not provide a way to support compression levels That's a non-starter. We can't just lie to the user about the compression level that is being used. If the user just does "-o compress=zlib" then you need to update btrfs_compress_set_level() to figure out the compression level that acomp is going to use and set that appropriately, so we can report to the user what is actually being used. Additionally if a user specifies a compression level you need to make sure we don't do acomp if it doesn't match what acomp is going to do. Finally, for the normal code review, there's a bunch of things that need to be fixed up before I take a closer look - We don't use pr_(), we have btrfs specific printk helpers, please use those. - We do 1 variable per line, fix up the variable declarations in your functions. Thanks, Josef
