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Wed, 25 Mar 2026 05:38:09 -0700 (PDT) Received: from thinky ([91.245.205.131]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-487116ee57esm120806865e9.14.2026.03.25.05.38.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2026 05:38:08 -0700 (PDT) Date: Wed, 25 Mar 2026 13:38:07 +0100 From: Andrey Albershteyn To: Christoph Hellwig Cc: Andrey Albershteyn , linux-xfs@vger.kernel.org, fsverity@lists.linux.dev, linux-fsdevel@vger.kernel.org, ebiggers@kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-btrfs@vger.kernel.org, djwong@kernel.org Subject: Re: [PATCH v5 07/25] iomap: introduce IOMAP_F_FSVERITY and teach writeback to handle fsverity Message-ID: References: <20260319170231.1455553-1-aalbersh@kernel.org> <20260319170231.1455553-8-aalbersh@kernel.org> <20260325080021.GF952@lst.de> Precedence: bulk X-Mailing-List: linux-btrfs@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: <20260325080021.GF952@lst.de> On 2026-03-25 09:00:21, Christoph Hellwig wrote: > > @@ -353,9 +353,16 @@ static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter, > > { > > const struct iomap *srcmap = iomap_iter_srcmap(iter); > > > > - return srcmap->type != IOMAP_MAPPED || > > - (srcmap->flags & IOMAP_F_NEW) || > > - pos >= i_size_read(iter->inode); > > + if (srcmap->type != IOMAP_MAPPED) > > + return true; > > + > > + if (srcmap->flags & IOMAP_F_NEW) > > + return true; > > + > > + if (srcmap->flags & IOMAP_F_FSVERITY) > > + return false; > > + > > + return pos >= i_size_read(iter->inode); > > This might be a good time to document the various reasons for needing > zeroing. something like this? --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -344,9 +344,27 @@ static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter, { const struct iomap *srcmap = iomap_iter_srcmap(iter); - return srcmap->type != IOMAP_MAPPED || - (srcmap->flags & IOMAP_F_NEW) || - pos >= i_size_read(iter->inode); + /* + * If this block is not mapped, we don't have any backing blocks to read + * yet + */ + if (srcmap->type != IOMAP_MAPPED) + return true; + + /* + * This block just got allocated and does not contain any meaningful data + */ + if (srcmap->flags & IOMAP_F_NEW) + return true; + + /* + * fsverity metadata is stored past i_size, we need to read it instead of + * zeroing + */ + if (srcmap->flags & IOMAP_F_FSVERITY) + return false; + + return pos >= i_size_read(iter->inode); } > > > +/* > > + * IO happens beyond inode EOF, fsverity metadata is stored there > > + */ > > +#define IOMAP_F_FSVERITY (1U << 10) > > This comment feels a bit too sparse. Here is my interpretation of what > this flag does: > > /* > * Indicates reads and writes of fsverity metadata. > * > * Fsverity metadata is stored after the regular file data and thus beyond > * i_size. > */ Thanks! I will update it -- - Andrey