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[49.179.32.121]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1f44c9d89b3sm75760405ad.292.2024.05.28.02.45.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 May 2024 02:45:18 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1sBtON-00DKcW-0N; Tue, 28 May 2024 19:45:15 +1000 Date: Tue, 28 May 2024 19:45:15 +1000 From: Dave Chinner To: "Pankaj Raghav (Samsung)" Cc: Matthew Wilcox , akpm@linux-foundation.org, djwong@kernel.org, brauner@kernel.org, chandan.babu@oracle.com, hare@suse.de, ritesh.list@gmail.com, john.g.garry@oracle.com, ziy@nvidia.com, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, gost.dev@samsung.com, p.raghav@samsung.com, mcgrof@kernel.org Subject: Re: [PATCH v5.1] fs: Allow fine-grained control of folio sizes Message-ID: References: <20240527210125.1905586-1-willy@infradead.org> <20240527220926.3zh2rv43w7763d2y@quentin> <20240528091202.qevisz7zr6n5ouj7@quentin> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240528091202.qevisz7zr6n5ouj7@quentin> On Tue, May 28, 2024 at 09:12:02AM +0000, Pankaj Raghav (Samsung) wrote: > On Tue, May 28, 2024 at 09:00:00AM +1000, Dave Chinner wrote: > > On Mon, May 27, 2024 at 11:43:43PM +0100, Matthew Wilcox wrote: > > > On Mon, May 27, 2024 at 11:39:47PM +0100, Matthew Wilcox wrote: > > > > > > + AS_FOLIO_ORDER_MIN = 16, > > > > > > + AS_FOLIO_ORDER_MAX = 21, /* Bits 16-25 are used for FOLIO_ORDER */ > > > > > > }; > > > > > > > > > > > > +#define AS_FOLIO_ORDER_MIN_MASK 0x001f0000 > > > > > > +#define AS_FOLIO_ORDER_MAX_MASK 0x03e00000 > > > > > > > > > > As you changed the mapping flag offset, these masks also needs to be > > > > > changed accordingly. > > > > > > > > That's why I did change them? > > > > > > How about: > > > > > > -#define AS_FOLIO_ORDER_MIN_MASK 0x001f0000 > > > -#define AS_FOLIO_ORDER_MAX_MASK 0x03e00000 > > > +#define AS_FOLIO_ORDER_MIN_MASK (31 << AS_FOLIO_ORDER_MIN) > > > +#define AS_FOLIO_ORDER_MAX_MASK (31 << AS_FOLIO_ORDER_MAX) > > > > Lots of magic numbers based on the order having only having 5 bits > > of resolution. Removing that magic looks like this: > > > > AS_FOLIO_ORDER_BITS = 5, > > I think this needs to be defined outside of the enum as 5 is already > taken by AS_NO_WRITEBACK_TAGS? But I like the idea of making it generic > like this. Duplicate values in assigned enums are legal and fairly common. This: enum { FOO = 1, BAR = 2, BAZ = 1, }; int main(int argc, char *argv[]) { printf("foo %d, bar %d, baz %d\n", FOO, BAR, BAZ); } compiles without warnings or errors and gives the output: foo 1, bar 2, baz 1 -Dave. -- Dave Chinner david@fromorbit.com