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Wed, 10 Jun 2026 06:55:33 -0700 (PDT) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 10 Jun 2026 15:55:32 +0200 Message-Id: Cc: , , , Subject: Re: [PATCH v2 23/83] block: rnull: add discard support From: "Malte Wechter" To: "Andreas Hindborg" , "Liam R. Howlett" , "Alice Ryhl" , "Anna-Maria Behnsen" , "Benno Lossin" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Boqun Feng" , "Danilo Krummrich" , "FUJITA Tomonori" , "Frederic Weisbecker" , "Gary Guo" , "Jens Axboe" , "John Stultz" , "Lorenzo Stoakes" , "Lyude Paul" , "Miguel Ojeda" , "Stephen Boyd" , "Thomas Gleixner" , "Trevor Gross" X-Mailer: aerc 0.21.0 References: <20260609-rnull-v6-19-rc5-send-v2-0-82c7404542e2@kernel.org> <20260609-rnull-v6-19-rc5-send-v2-23-82c7404542e2@kernel.org> In-Reply-To: <20260609-rnull-v6-19-rc5-send-v2-23-82c7404542e2@kernel.org> X-Rspamd-Queue-Id: 5744FC000A X-Stat-Signature: f5k77na54ix7ub9ao3t9gnyxksctbdkp X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1781099736-108261 X-HE-Meta: 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 6tRjuwx9 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue Jun 9, 2026 at 9:08 PM CEST, Andreas Hindborg wrote: > Add support for discard operations to the rnull block driver: > - Add discard module parameter and configfs attribute. > - Set max_hw_discard_sectors when discard is enabled. > - Add sector occupancy tracking. > - Add discard handling that frees sectors and removes empty pages. > - Discard operations require memory backing to function. > > The discard feature uses a bitmap to track which sectors in each page are > occupied, allowing cleanup of pages when they are empty. > > Signed-off-by: Andreas Hindborg > --- > drivers/block/rnull/configfs.rs | 15 +++++ > drivers/block/rnull/rnull.rs | 120 ++++++++++++++++++++++++++++++++++= +----- > 2 files changed, 121 insertions(+), 14 deletions(-) > > diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/config= fs.rs > index 2f3fa81ea121..e47399cd45a4 100644 > --- a/drivers/block/rnull/configfs.rs > +++ b/drivers/block/rnull/configfs.rs ... > } > }) > ); > + > +configfs_attribute!(DeviceConfig, 10, > + show: |this, page| show_field(this.data.lock().discard, page), > + store: |this, page| store_with_power_check(this, page, |data, page| = { > + if !data.memory_backed { > + return Err(EINVAL); > + } > + data.discard =3D kstrtobool_bytes(page)?; > + Ok(()) > + }) > +); Should it be ok to set 'discard' to 0 if 'emory_backed' is not set? In the C null_blk driver, 'discard' defaults to 0 if 'memory_backed' is not= set, it is also ignored (and defaulted to 0) if 'zoned' is enabled. Best regards, Malte