Re: [PATCH v5 10/11] block: remove bio_get_nr_vecs()
From: Steven Whitehouse
Date: Tue Jul 07 2015 - 05:04:18 EST
Hi,
On 06/07/15 18:21, Ming Lin wrote:
On Mon, Jul 6, 2015 at 3:58 AM, Steven Whitehouse <swhiteho@xxxxxxxxxx> wrote:
Hi,
On 06/07/15 08:44, Ming Lin wrote:
From: Kent Overstreet <kent.overstreet@xxxxxxxxx>
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@xxxxxxxxxx>
Steve.
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