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[49.180.13.202]) by smtp.gmail.com with ESMTPSA id u13-20020a170902a60d00b001ae0a4b1d3fsm4174996plq.153.2023.06.21.19.58.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jun 2023 19:58:11 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1qCAWO-00Egjy-26; Thu, 22 Jun 2023 12:58:08 +1000 Date: Thu, 22 Jun 2023 12:58:08 +1000 From: Dave Chinner To: "Darrick J. Wong" Cc: Kent Overstreet , linux-xfs@vger.kernel.org, willy@infradead.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCHSET v25.0 0/7] xfs: stage repair information in pageable memory Message-ID: References: <20230526000020.GJ11620@frogsfrogsfrogs> <168506056447.3729324.13624212283929857624.stgit@frogsfrogsfrogs> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <168506056447.3729324.13624212283929857624.stgit@frogsfrogsfrogs> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, May 25, 2023 at 05:28:55PM -0700, Darrick J. Wong wrote: > Hi all, > > In general, online repair of an indexed record set walks the filesystem > looking for records. These records are sorted and bulk-loaded into a > new btree. To make this happen without pinning gigabytes of metadata in > memory, first create an abstraction ('xfile') of memfd files so that > kernel code can access paged memory, and then an array abstraction > ('xfarray') based on xfiles so that online repair can create an array of > new records without pinning memory. > > These two data storage abstractions are critical for repair of space > metadata -- the memory used is pageable, which helps us avoid pinning > kernel memory and driving OOM problems; and they are byte-accessible > enough that we can use them like (very slow and programmatic) memory > buffers. > > Later patchsets will build on this functionality to provide blob storage > and btrees. Apart from the need for a struct xfs-mount just for the xfile name at creation time, this all looks OK. Reviewed-by: Dave Chinner Is there any specific test harness for this infrastructure, or is it just validated by having other functions built on top of it "work correctly"? -Dave. -- Dave Chinner david@fromorbit.com