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Wong" To: Christoph Hellwig Cc: Christian Brauner , Jan Kara , Carlos Maiolino , Andrew Morton , willy@infradead.org, dlemoal@kernel.org, hans.holmberg@wdc.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH 3/3] xfs: set s_min_writeback_pages for zoned file systems Message-ID: <20251015160158.GA6188@frogsfrogsfrogs> References: <20251015062728.60104-1-hch@lst.de> <20251015062728.60104-4-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251015062728.60104-4-hch@lst.de> X-Rspam-User: X-Rspamd-Queue-Id: 0456A100011 X-Rspamd-Server: rspam03 X-Stat-Signature: 6xq94u984noxtt6ijy6kw3zm1mn1peur X-HE-Tag: 1760544119-322140 X-HE-Meta: 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 xcyLUhDd WrIr4q4GWw1rYvRtIG5R1pPB6cGQXlDcAKUqawY0OZJH6sjWlkZNKuizqrdXeFel2ExPqlVbfnjsSZ2YushqW2W+wi6m0PIon4FMkhysRMLIAdNytomkolFoTD8FFKiQcd6CZ45qCQTjL+6LxhrpRuGCazC1FR22EtCwZFqvphK2+6EhxSQP74fT1VD6fDTIpTOw4Jy29iavVzmyoe10vJf9f2E1E/y66kZjldu/ejugxGYhEZTclJSGm9wIfUHpNQlXhxZtOwRAE6MBm5EsJ0DAPk9ORzyEe2ULkqE2hRk7xIRhn0kDvUpjc2Xaezss+BBx7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Oct 15, 2025 at 03:27:16PM +0900, Christoph Hellwig wrote: > Set s_min_writeback_pages to the zone size, so that writeback always > writes up to a full zone. This ensures that writeback does not add > spurious file fragmentation when writing back a large number of > files that are larger than the zone size. > > Fixes: 4e4d52075577 ("xfs: add the zoned space allocator") > Signed-off-by: Christoph Hellwig > --- > fs/xfs/xfs_zone_alloc.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/xfs_zone_alloc.c b/fs/xfs/xfs_zone_alloc.c > index 1147bacb2da8..0f4e460fd3ea 100644 > --- a/fs/xfs/xfs_zone_alloc.c > +++ b/fs/xfs/xfs_zone_alloc.c > @@ -1215,6 +1215,7 @@ xfs_mount_zones( > .mp = mp, > }; > struct xfs_buftarg *bt = mp->m_rtdev_targp; > + xfs_extlen_t zone_blocks = mp->m_groups[XG_TYPE_RTG].blocks; > int error; > > if (!bt) { > @@ -1245,10 +1246,12 @@ xfs_mount_zones( > return -ENOMEM; > > xfs_info(mp, "%u zones of %u blocks (%u max open zones)", > - mp->m_sb.sb_rgcount, mp->m_groups[XG_TYPE_RTG].blocks, > - mp->m_max_open_zones); > + mp->m_sb.sb_rgcount, zone_blocks, mp->m_max_open_zones); > trace_xfs_zones_mount(mp); > > + mp->m_super->s_min_writeback_pages = > + XFS_FSB_TO_B(mp, zone_blocks) >> PAGE_SHIFT; Hmm. The maximum rtgroup (and hence zone) size is 2^31-1 blocks. That quantity is casted to int64_t by FSB_TO_B, then shifted down by PAGE_SHIFT. So I think there's no chance of an overflow here, especially if s_min_writeback_pages becomes type long. Reviewed-by: "Darrick J. Wong" --D > + > if (bdev_is_zoned(bt->bt_bdev)) { > error = blkdev_report_zones(bt->bt_bdev, > XFS_FSB_TO_BB(mp, mp->m_sb.sb_rtstart), > -- > 2.47.3 > >