linux-ext4 - Re: [PATCH v3] fsverity: stop using PG

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Date:   Thu, 24 Nov 2022 19:09:13 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-fsdevel@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-fscrypt@...r.kernel.org,
        Matthew Wilcox <willy@...radead.org>,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH v3] fsverity: stop using PG_error to track error status

On Fri, Nov 25, 2022 at 11:06:43AM +0800, Chao Yu wrote:
> On 2022/11/24 6:19, Eric Biggers wrote:
> > On Thu, Nov 10, 2022 at 12:21:06AM -0800, Eric Biggers wrote:
> > > On Fri, Oct 28, 2022 at 10:58:07AM -0700, Eric Biggers wrote:
> > > > From: Eric Biggers <ebiggers@...gle.com>
> > > > 
> > > > As a step towards freeing the PG_error flag for other uses, change ext4
> > > > and f2fs to stop using PG_error to track verity errors.  Instead, if a
> > > > verity error occurs, just mark the whole bio as failed.  The coarser
> > > > granularity isn't really a problem since it isn't any worse than what
> > > > the block layer provides, and errors from a multi-page readahead aren't
> > > > reported to applications unless a single-page read fails too.
> > > > 
> > > > f2fs supports compression, which makes the f2fs changes a bit more
> > > > complicated than desired, but the basic premise still works.
> > > > 
> > > > Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> > > > ---
> > > > 
> > > > In v3, I made a small simplification to the f2fs changes.  I'm also only
> > > > sending the fsverity patch now, since the fscrypt one is now upstream.
> > > > 
> > > >   fs/ext4/readpage.c |  8 ++----
> > > >   fs/f2fs/compress.c | 64 ++++++++++++++++++++++------------------------
> > > >   fs/f2fs/data.c     | 48 +++++++++++++++++++---------------
> 
> Hi Eric,
> 
> Result of "grep PageError fs/f2fs/* -n"
> 
> ...
> fs/f2fs/gc.c:1364:      ClearPageError(page);
> fs/f2fs/inline.c:177:   ClearPageError(page);
> fs/f2fs/node.c:1649:    ClearPageError(page);
> fs/f2fs/node.c:2078:            if (TestClearPageError(page))
> fs/f2fs/segment.c:3406: ClearPageError(page);
> 
> Any plan to remove above PG_error flag operations? Maybe in a separated patch?
> 

Those are all for writes, not reads.  So I didn't want to touch them in this
patch, which is only about reads.

- Eric