From: Dan Carpenter <dan.carpenter@oracle.com>
To: Gao Xiang <gaoxiang25@huawei.com>
Cc: miaoxie@huawei.com, xiang@kernel.org, linux-erofs@lists.ozlabs.org
Subject: Re: [bug report] staging: erofs: introduce erofs_grab_bio
Date: Wed, 28 Aug 2019 14:36:13 +0300 [thread overview]
Message-ID: <20190828113612.GB8372@kadam> (raw)
In-Reply-To: <20190828110249.GA56298@architecture4>
On Wed, Aug 28, 2019 at 07:02:49PM +0800, Gao Xiang wrote:
> Hi Dan,
>
> On Wed, Aug 28, 2019 at 01:55:41PM +0300, Dan Carpenter wrote:
> > Hello Gao Xiang,
> >
> > The patch 8be31270362b: "staging: erofs: introduce erofs_grab_bio"
> > from Aug 21, 2018, leads to the following static checker warning:
> >
> > fs/erofs/zdata.c:1272 z_erofs_vle_submit_all()
> > error: 'bio' dereferencing possible ERR_PTR()
> >
> > fs/erofs/zdata.c
> > 1259 if (bio && force_submit) {
> > 1260 submit_bio_retry:
> > 1261 __submit_bio(bio, REQ_OP_READ, 0);
> > 1262 bio = NULL;
> > 1263 }
> > 1264
> > 1265 if (!bio) {
> > 1266 bio = erofs_grab_bio(sb, first_index + i,
> > 1267 BIO_MAX_PAGES, bi_private,
> > 1268 z_erofs_vle_read_endio, true);
> >
> > This assumes erofs_grab_bio() can't fail. It returns ERR_PTR(-ENOMEM)
> > on failure.
>
> I think there is no problem at all as well.
> The last argument of erofs_grab_bio is nofail, and here is "true".
>
> 415 static inline struct bio *erofs_grab_bio(struct super_block *sb,
> 416 erofs_blk_t blkaddr,
> 417 unsigned int nr_pages,
> 418 void *bi_private, bio_end_io_t endio,
> 419 bool nofail)
> 420 {
> 421 const gfp_t gfp = GFP_NOIO;
> 422 struct bio *bio;
> 423
> 424 do {
> 425 if (nr_pages == 1) {
> 426 bio = bio_alloc(gfp | (nofail ? __GFP_NOFAIL : 0), 1);
> 427 if (unlikely(!bio)) {
> 428 DBG_BUGON(nofail);
> 429 return ERR_PTR(-ENOMEM);
> 430 }
> 431 break;
> 432 }
> 433 bio = bio_alloc(gfp, nr_pages);
> 434 nr_pages /= 2;
> 435 } while (unlikely(!bio));
> 436
> 437 bio->bi_end_io = endio;
> 438 bio_set_dev(bio, sb->s_bdev);
> 439 bio->bi_iter.bi_sector = (sector_t)blkaddr << LOG_SECTORS_PER_BLOCK;
> 440 bio->bi_private = bi_private;
> 441 return bio;
> 442 }
>
> You can see __GFP_NOFAIL is set, Am I missing something?
>
Ah. Yes. You're right.
regards,
dan
next prev parent reply other threads:[~2019-08-28 11:36 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-28 10:55 [bug report] staging: erofs: introduce erofs_grab_bio Dan Carpenter
2019-08-28 11:02 ` Gao Xiang
2019-08-28 11:36 ` Dan Carpenter [this message]
2019-08-28 11:40 ` Gao Xiang
2019-08-28 11:39 ` Gao Xiang
2019-08-28 12:11 ` Dan Carpenter
2019-08-28 12:22 ` Gao Xiang
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