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[49.180.20.59]) by smtp.gmail.com with ESMTPSA id q4-20020a056a0002a400b006be4bb0d2dcsm3375711pfs.149.2023.11.04.13.51.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 04 Nov 2023 13:51:05 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1qzNbi-008FsO-21; Sun, 05 Nov 2023 07:51:02 +1100 Date: Sun, 5 Nov 2023 07:51:02 +1100 From: Dave Chinner To: Kent Overstreet Cc: Christian Brauner , Mateusz Guzik , Dave Chinner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-bcachefs@vger.kernel.org, Alexander Viro Subject: Re: (subset) [PATCH 22/32] vfs: inode cache conversion to hash-bl Message-ID: References: <20230509165657.1735798-23-kent.overstreet@linux.dev> <20230523-zujubeln-heizsysteme-f756eefe663e@brauner> <20231019153040.lj3anuescvdprcq7@f> <20231019155958.7ek7oyljs6y44ah7@f> <20231031-proviant-anrollen-d2245037ce97@brauner> <20231102023615.jsv2ffe4rbivgsja@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231102023615.jsv2ffe4rbivgsja@moria.home.lan> Precedence: bulk List-ID: X-Mailing-List: linux-bcachefs@vger.kernel.org On Wed, Nov 01, 2023 at 10:36:15PM -0400, Kent Overstreet wrote: > On Tue, Oct 31, 2023 at 12:02:47PM +0100, Christian Brauner wrote: > > > The follow up including a statement about "being arsed" once more was > > > to Christian, not you and was rather "tongue in cheek". > > > > Fyi, I can't be arsed to be talked to like that. > > > > > Whether the patch is ready for reviews and whatnot is your call to > > > make as the author. > > > > This is basically why that patch never staid in -next. Dave said this > > patch is meaningless without his other patchs and I had no reason to > > doubt that claim nor currently the cycles to benchmark and disprove it. > > It was a big benefit to bcachefs performance, and I've had it in my tree > for quite some time. Was there any other holdup? Plenty. - A lack of recent validation against ext4, btrfs and other filesystems. - the loss of lockdep coverage by moving to bit locks - it breaks CONFIG_PREEMPT_RT=y because we nest other spinlocks inside the inode_hash_lock and we can't do that if we convert the inode hash to bit locks because RT makes spinlocks sleeping locks. - There's been additions for lockless RCU inode hash lookups from AFS and ext4 in weird, uncommon corner cases and I have no idea how to validate they still work correctly with hash-bl. I suspect they should just go away with hash-bl, but.... There's more, but these are the big ones. -Dave. -- Dave Chinner david@fromorbit.com