linux-ext4 - Re: [PATCH V3 4/7] fs/mpage.c: Integrate read callbacks

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Message-Id: <1847149.B8S3WBCFIi@localhost.localdomain>
Date:   Tue, 25 Jun 2019 11:51:14 +0530
From:   Chandan Rajendra <chandan@...ux.ibm.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-fscrypt@...r.kernel.org, tytso@....edu,
        adilger.kernel@...ger.ca, jaegeuk@...nel.org, yuchao0@...wei.com,
        hch@...radead.org
Subject: Re: [PATCH V3 4/7] fs/mpage.c: Integrate read callbacks

On Saturday, June 22, 2019 2:44:55 AM IST Eric Biggers wrote:
> On Sun, Jun 16, 2019 at 09:38:10PM +0530, Chandan Rajendra wrote:
> > This commit adds code to make do_mpage_readpage() to be "read callbacks"
> > aware i.e. for files requiring decryption, do_mpage_readpage() now
> > sets up the read callbacks state machine when allocating a bio and later
> > starts execution of the state machine after file data is read from the
> > underlying disk.
> > 
> > Signed-off-by: Chandan Rajendra <chandan@...ux.ibm.com>
> > ---
> >  fs/mpage.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/mpage.c b/fs/mpage.c
> > index 436a85260394..611ad122fc92 100644
> > --- a/fs/mpage.c
> > +++ b/fs/mpage.c
> > @@ -30,6 +30,7 @@
> >  #include <linux/backing-dev.h>
> >  #include <linux/pagevec.h>
> >  #include <linux/cleancache.h>
> > +#include <linux/read_callbacks.h>
> >  #include "internal.h"
> >  
> >  /*
> > @@ -49,6 +50,8 @@ static void mpage_end_io(struct bio *bio)
> >  	struct bio_vec *bv;
> >  	struct bvec_iter_all iter_all;
> >  
> > +	if (read_callbacks_end_bio(bio))
> > +		return;
> >  	bio_for_each_segment_all(bv, bio, iter_all) {
> >  		struct page *page = bv->bv_page;
> >  		page_endio(page, bio_op(bio),
> > @@ -309,6 +312,12 @@ static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
> >  					gfp);
> >  		if (args->bio == NULL)
> >  			goto confused;
> > +
> > +		if (read_callbacks_setup(inode, args->bio, NULL)) {
> > +			bio_put(args->bio);
> > +			args->bio = NULL;
> > +			goto confused;
> > +		}
> >  	}
> >  
> >  	length = first_hole << blkbits;
> > @@ -330,7 +339,7 @@ static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
> >  confused:
> >  	if (args->bio)
> >  		args->bio = mpage_bio_submit(REQ_OP_READ, op_flags, args->bio);
> > -	if (!PageUptodate(page))
> > +	if (!PageUptodate(page) && !PageError(page))
> >  		block_read_full_page(page, args->get_block);
> >  	else
> >  		unlock_page(page);
> 
> Why is the !PageError() check needed here?
> 

Sorry, Its a remnant from when I was debugging the patchset. I will remove
this.

-- 
chandan