From: Andrey Albershteyn <aalbersh@redhat.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
fsverity@lists.linux.dev, djwong@kernel.org,
david@fromorbit.com, dchinner@redhat.com
Subject: Re: [PATCH v3 07/28] fsverity: always use bitmap to track verified status
Date: Mon, 16 Oct 2023 13:52:28 +0200 [thread overview]
Message-ID: <256y7jz5u6yj6d7gxoy7oo26eltcpcy43ugc2plog6fpcyz3tq@visdz2fzs7yc> (raw)
In-Reply-To: <20231012072746.GA2100@sol.localdomain>
On 2023-10-12 00:27:46, Eric Biggers wrote:
> On Wed, Oct 11, 2023 at 03:03:55PM +0200, Andrey Albershteyn wrote:
> > > How complicated would it be to keep supporting using the page bit when
> > > merkle_tree_block_size == page_size and the filesystem supports it? It's an
> > > efficient solution, so it would be a shame to lose it. Also it doesn't have the
> > > max file size limit that the bitmap has.
> >
> > Well, I think it's possible but my motivation was to step away from
> > page manipulation as much as possible with intent to not affect other
> > filesystems too much. I can probably add handling of this case to
> > fsverity_read_merkle_tree_block() but fs/verity still will create
> > bitmap and have a limit. The other way is basically revert changes
> > done in patch 09, then, it probably will be quite a mix of page/block
> > handling in fs/verity/verify.c
>
> The page-based caching still has to be supported anyway, since that's what the
> other filesystems that support fsverity use, and it seems you don't plan to
> change that. The question is where the "block verified" flags should be stored.
> Currently there are two options: PG_checked and the separate bitmap. I'm not
> yet convinced that removing the support for the PG_checked method is a good
> change. PG_checked is a nice solution for the cases where it can be used; it
> requires no extra memory, no locking, and has no max file size. Also, this
> change seems mostly orthogonal to what you're actually trying to accomplish.
Yes, I was trying to combine PG_checked and bitmap in the way it can
be also used by XFS. I will try change this patch to not drop
merkle_tree_block_size == page_size case.
> > > > Also, this patch removes spinlock. The lock was used to reset bits
> > > > in bitmap belonging to one page. This patch works only with one
> > > > Merkle tree block and won't reset other blocks status.
> > >
> > > The spinlock is needed when there are multiple Merkle tree blocks per page and
> > > the filesystem is using the page-based caching. So I don't think you can remove
> > > it. Can you elaborate on why you feel it can be removed?
> >
> > With this patch is_hash_block_verified() doesn't reset bits for
> > blocks belonging to the same page. Even if page is re-instantiated
> > only one block is checked in this case. So, when other blocks are
> > checked they are reset.
> >
> > if (block_cached)
> > return test_bit(hblock_idx, vi->hash_block_verified);
>
> When part of the Merkle tree cache is evicted and re-instantiated, whether that
> part is a "page" or something else, the verified status of all the blocks
> contained in that part need to be invalidated so that they get re-verified. The
> existing code does that. I don't see how your proposed code does that.
Oh, I see the problem now, I will revert it back.
--
- Andrey
next prev parent reply other threads:[~2023-10-16 11:52 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-06 18:48 [PATCH v3 00/28] fs-verity support for XFS Andrey Albershteyn
2023-10-06 18:48 ` [PATCH v3 01/28] xfs: Add new name to attri/d Andrey Albershteyn
2023-10-06 18:48 ` [PATCH v3 02/28] xfs: add parent pointer support to attribute code Andrey Albershteyn
2023-10-06 18:48 ` [PATCH v3 03/28] xfs: define parent pointer xattr format Andrey Albershteyn
2023-10-06 18:48 ` [PATCH v3 04/28] xfs: Add xfs_verify_pptr Andrey Albershteyn
2023-10-11 1:01 ` Darrick J. Wong
2023-10-11 11:09 ` Andrey Albershteyn
2023-10-06 18:48 ` [PATCH v3 05/28] fs: add FS_XFLAG_VERITY for fs-verity sealed inodes Andrey Albershteyn
2023-10-11 4:05 ` Eric Biggers
2023-10-11 11:06 ` Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 06/28] fsverity: add drop_page() callout Andrey Albershteyn
2023-10-11 3:06 ` Eric Biggers
2023-10-11 11:11 ` Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 07/28] fsverity: always use bitmap to track verified status Andrey Albershteyn
2023-10-11 3:15 ` Eric Biggers
2023-10-11 13:03 ` Andrey Albershteyn
2023-10-12 7:27 ` Eric Biggers
2023-10-13 3:12 ` Darrick J. Wong
2023-10-17 4:58 ` Eric Biggers
2023-10-18 2:35 ` Darrick J. Wong
2023-10-17 6:01 ` Christoph Hellwig
2023-10-16 11:52 ` Andrey Albershteyn [this message]
2023-10-17 5:57 ` Christoph Hellwig
2023-10-17 17:49 ` Eric Biggers
2023-10-06 18:49 ` [PATCH v3 08/28] fsverity: pass Merkle tree block size to ->read_merkle_tree_page() Andrey Albershteyn
2023-10-11 3:17 ` Eric Biggers
2023-10-11 11:13 ` Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 09/28] fsverity: pass log_blocksize to end_enable_verity() Andrey Albershteyn
2023-10-11 3:19 ` Eric Biggers
2023-10-11 11:17 ` Andrey Albershteyn
2023-10-12 7:34 ` Eric Biggers
2023-10-06 18:49 ` [PATCH v3 10/28] fsverity: operate with Merkle tree blocks instead of pages Andrey Albershteyn
2023-10-07 4:02 ` kernel test robot
2023-10-11 3:56 ` Eric Biggers
2023-10-16 13:00 ` Christoph Hellwig
2023-10-06 18:49 ` [PATCH v3 11/28] iomap: pass readpage operation to read path Andrey Albershteyn
2023-10-11 18:31 ` Darrick J. Wong
2023-10-16 12:35 ` Andrey Albershteyn
2023-10-16 9:15 ` Christoph Hellwig
2023-10-16 12:32 ` Andrey Albershteyn
2023-10-16 12:58 ` Christoph Hellwig
2023-10-06 18:49 ` [PATCH v3 12/28] iomap: allow filesystem to implement read path verification Andrey Albershteyn
2023-10-11 18:39 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 13/28] xfs: add XBF_VERITY_CHECKED xfs_buf flag Andrey Albershteyn
2023-10-11 18:54 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 14/28] xfs: add XFS_DA_OP_BUFFER to make xfs_attr_get() return buffer Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 15/28] xfs: introduce workqueue for post read IO work Andrey Albershteyn
2023-10-11 18:55 ` Darrick J. Wong
2023-10-16 12:37 ` Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 16/28] xfs: add bio_set and submit_io for ioend post-processing Andrey Albershteyn
2023-10-11 18:47 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 17/28] xfs: add attribute type for fs-verity Andrey Albershteyn
2023-10-11 18:48 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 18/28] xfs: make xfs_buf_get() to take XBF_* flags Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 19/28] xfs: add XBF_DOUBLE_ALLOC to increase size of the buffer Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 20/28] xfs: add fs-verity ro-compat flag Andrey Albershteyn
2023-10-11 18:56 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 21/28] xfs: add inode on-disk VERITY flag Andrey Albershteyn
2023-10-11 18:57 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 22/28] xfs: initialize fs-verity on file open and cleanup on inode destruction Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 23/28] xfs: don't allow to enable DAX on fs-verity sealsed inode Andrey Albershteyn
2023-10-11 19:00 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 24/28] xfs: disable direct read path for fs-verity sealed files Andrey Albershteyn
2023-10-11 19:02 ` Darrick J. Wong
2023-10-06 18:49 ` [PATCH v3 25/28] xfs: add fs-verity support Andrey Albershteyn
2023-10-06 23:40 ` kernel test robot
2023-10-11 1:39 ` Darrick J. Wong
2023-10-11 14:36 ` Andrey Albershteyn
2023-10-18 19:18 ` kernel test robot
2023-10-06 18:49 ` [PATCH v3 26/28] xfs: make scrub aware of verity dinode flag Andrey Albershteyn
2023-10-11 1:06 ` Darrick J. Wong
2023-10-11 14:37 ` Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 27/28] xfs: add fs-verity ioctls Andrey Albershteyn
2023-10-06 18:49 ` [PATCH v3 28/28] xfs: enable ro-compat fs-verity flag Andrey Albershteyn
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