Messages in this thread Patch in this message | | | Subject | Re: [PATCH] ext4: bio_alloc never fails | From | Ritesh Harjani <> | Date | Wed, 30 Oct 2019 15:43:10 +0530 |
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On 10/30/19 9:56 AM, Gao Xiang wrote: > Similar to [1] [2], it seems a trivial cleanup since > bio_alloc can handle memory allocation as mentioned in > fs/direct-io.c (also see fs/block_dev.c, fs/buffer.c, ..) >
AFAIU, the reason is that, bio_alloc with __GFP_DIRECT_RECLAIM flags guarantees bio allocation under some given restrictions, as stated in fs/direct-io.c So here it is ok to not check for NULL value from bio_alloc.
I think we can update above info too in your commit msg.
> [1] https://lore.kernel.org/r/20191030035518.65477-1-gaoxiang25@huawei.com > [2] https://lore.kernel.org/r/20190830162812.GA10694@infradead.org > Signed-off-by: Gao Xiang <gaoxiang25@huawei.com> > --- > fs/ext4/page-io.c | 11 +++-------- > fs/ext4/readpage.c | 2 -- > 2 files changed, 3 insertions(+), 10 deletions(-) > > diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c > index 12ceadef32c5..f1f7b6601780 100644 > --- a/fs/ext4/page-io.c > +++ b/fs/ext4/page-io.c > @@ -358,14 +358,12 @@ void ext4_io_submit_init(struct ext4_io_submit *io, > io->io_end = NULL; > } > > -static int io_submit_init_bio(struct ext4_io_submit *io, > - struct buffer_head *bh) > +static void io_submit_init_bio(struct ext4_io_submit *io, > + struct buffer_head *bh) > { > struct bio *bio; > > bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES); > - if (!bio) > - return -ENOMEM; > bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); > bio_set_dev(bio, bh->b_bdev); > bio->bi_end_io = ext4_end_bio; > @@ -373,7 +371,6 @@ static int io_submit_init_bio(struct ext4_io_submit *io, > io->io_bio = bio; > io->io_next_block = bh->b_blocknr; > wbc_init_bio(io->io_wbc, bio); > - return 0; > } > > static int io_submit_add_bh(struct ext4_io_submit *io, > @@ -388,9 +385,7 @@ static int io_submit_add_bh(struct ext4_io_submit *io, > ext4_io_submit(io); > } > if (io->io_bio == NULL) { > - ret = io_submit_init_bio(io, bh); > - if (ret) > - return ret; > + io_submit_init_bio(io, bh); > io->io_bio->bi_write_hint = inode->i_write_hint; > } > ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
Also we can further simplify it like below. Please check.
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index f1f7b6601780..a3a2edeb3bbf 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -373,7 +373,7 @@ static void io_submit_init_bio(struct ext4_io_submit *io, wbc_init_bio(io->io_wbc, bio); }
-static int io_submit_add_bh(struct ext4_io_submit *io, +static void io_submit_add_bh(struct ext4_io_submit *io, struct inode *inode, struct page *page, struct buffer_head *bh) @@ -393,7 +393,6 @@ static int io_submit_add_bh(struct ext4_io_submit *io, goto submit_and_retry; wbc_account_cgroup_owner(io->io_wbc, page, bh->b_size); io->io_next_block++; - return 0; }
int ext4_bio_write_page(struct ext4_io_submit *io, @@ -495,30 +494,23 @@ int ext4_bio_write_page(struct ext4_io_submit *io, do { if (!buffer_async_write(bh)) continue; - ret = io_submit_add_bh(io, inode, bounce_page ?: page, bh); - if (ret) { - /* - * We only get here on ENOMEM. Not much else - * we can do but mark the page as dirty, and - * better luck next time. - */ - break; - } + io_submit_add_bh(io, inode, bounce_page ?: page, bh); nr_submitted++; clear_buffer_dirty(bh); } while ((bh = bh->b_this_page) != head);
- /* Error stopped previous loop? Clean up buffers... */ - if (ret) { - out: - fscrypt_free_bounce_page(bounce_page); - printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret); - redirty_page_for_writepage(wbc, page); - do { - clear_buffer_async_write(bh); - bh = bh->b_this_page; - } while (bh != head); - } + goto unlock; + +out: + fscrypt_free_bounce_page(bounce_page); + printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret); + redirty_page_for_writepage(wbc, page); + do { + clear_buffer_async_write(bh); + bh = bh->b_this_page; + } while (bh != head); + +unlock: unlock_page(page); /* Nothing submitted - we have to end page writeback */ if (!nr_submitted)
-ritesh
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