Messages in this thread | | | Date | Tue, 07 Jul 2015 10:04:01 +0100 | From | Steven Whitehouse <> | Subject | Re: [PATCH v5 10/11] block: remove bio_get_nr_vecs() |
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Hi,
On 06/07/15 18:21, Ming Lin wrote: > On Mon, Jul 6, 2015 at 3:58 AM, Steven Whitehouse <swhiteho@redhat.com> wrote: >> Hi, >> >> >> On 06/07/15 08:44, Ming Lin wrote: >>> From: Kent Overstreet <kent.overstreet@gmail.com> >>> >>> We can always fill up the bio now, no need to estimate the possible >>> size based on queue parameters. >> [snip] >>> diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c >>> index 2c1ae86..64d3116 100644 >>> --- a/fs/gfs2/lops.c >>> +++ b/fs/gfs2/lops.c >>> @@ -261,18 +261,11 @@ void gfs2_log_flush_bio(struct gfs2_sbd *sdp, int rw) >>> static struct bio *gfs2_log_alloc_bio(struct gfs2_sbd *sdp, u64 blkno) >>> { >>> struct super_block *sb = sdp->sd_vfs; >>> - unsigned nrvecs = bio_get_nr_vecs(sb->s_bdev); >>> struct bio *bio; >>> BUG_ON(sdp->sd_log_bio); >>> - while (1) { >>> - bio = bio_alloc(GFP_NOIO, nrvecs); >>> - if (likely(bio)) >>> - break; >>> - nrvecs = max(nrvecs/2, 1U); >>> - } >>> - >>> + bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES); >>> bio->bi_iter.bi_sector = blkno * (sb->s_blocksize >> 9); >>> bio->bi_bdev = sb->s_bdev; >>> bio->bi_end_io = gfs2_end_log_write; >> >> When I wrote this loop I understood that bio_alloc(GFP_NOIO, x) was only guaranteed to be successful in the case x = 1, and that for x > 1, it might return NULL. Does this now mean that for x = BIO_MAX_PAGES it will be guaranteed to never return NULL in this case? > Yes, it's guaranteed. > > https://lkml.org/lkml/2013/11/26/47 > > commit df2cb6daa4cbc
Ok. Feel free to add: Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Steve.
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