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[68.160.166.30]) by smtp.gmail.com with ESMTPSA id b28-20020a05620a127c00b0075941df3365sm1164925qkl.52.2023.05.19.08.23.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 May 2023 08:23:13 -0700 (PDT) Date: Fri, 19 May 2023 11:23:12 -0400 From: Mike Snitzer To: Sarthak Kukreti , Joe Thornber Cc: dm-devel@redhat.com, linux-block@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jens Axboe , Theodore Ts'o , "Michael S. Tsirkin" , "Darrick J. Wong" , Jason Wang , Bart Van Assche , Christoph Hellwig , Andreas Dilger , Stefan Hajnoczi , Brian Foster , Alasdair Kergon Subject: Re: [PATCH v7 4/5] dm-thin: Add REQ_OP_PROVISION support Message-ID: References: <20230518223326.18744-1-sarthakkukreti@chromium.org> <20230518223326.18744-5-sarthakkukreti@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230518223326.18744-5-sarthakkukreti@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, May 18 2023 at 6:33P -0400, Sarthak Kukreti wrote: > dm-thinpool uses the provision request to provision > blocks for a dm-thin device. dm-thinpool currently does not > pass through REQ_OP_PROVISION to underlying devices. > > For shared blocks, provision requests will break sharing and copy the > contents of the entire block. Additionally, if 'skip_block_zeroing' > is not set, dm-thin will opt to zero out the entire range as a part > of provisioning. > > Signed-off-by: Sarthak Kukreti > --- > drivers/md/dm-thin.c | 74 +++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 70 insertions(+), 4 deletions(-) > > diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c > index 2b13c949bd72..f1b68b558cf0 100644 > --- a/drivers/md/dm-thin.c > +++ b/drivers/md/dm-thin.c > @@ -1245,8 +1247,8 @@ static int io_overlaps_block(struct pool *pool, struct bio *bio) > > static int io_overwrites_block(struct pool *pool, struct bio *bio) > { > - return (bio_data_dir(bio) == WRITE) && > - io_overlaps_block(pool, bio); > + return (bio_data_dir(bio) == WRITE) && io_overlaps_block(pool, bio) && > + bio_op(bio) != REQ_OP_PROVISION; > } > > static void save_and_set_endio(struct bio *bio, bio_end_io_t **save, > @@ -1394,6 +1396,9 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block, > m->data_block = data_block; > m->cell = cell; > > + if (bio && bio_op(bio) == REQ_OP_PROVISION) > + m->bio = bio; > + > /* > * If the whole block of data is being overwritten or we are not > * zeroing pre-existing data, we can issue the bio immediately. This doesn't seem like the best way to address avoiding passdown of provision bios (relying on process_prepared_mapping's implementation that happens to do the right thing if m->bio set). Doing so cascades into relying on complete_overwrite_bio() happening to _not_ actually being specific to "overwrite" bios. I don't have a better suggestion yet but will look closer. Just think this needs to be formalized a bit more rather than it happening to "just work". Cc'ing Joe to see what he thinks too. This is something we can clean up with a follow-on patch though, so not a show-stopper for this series. Mike