linux-kernel - [PATCH V7 15/24] fs/buffer.c: use bvec iterator to truncate the bio

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Date:   Wed, 27 Jun 2018 20:45:39 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Jens Axboe <axboe@...com>, Christoph Hellwig <hch@...radead.org>,
        Kent Overstreet <kent.overstreet@...il.com>
Cc:     David Sterba <dsterba@...e.cz>, Huang Ying <ying.huang@...el.com>,
        Mike Snitzer <snitzer@...hat.com>,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        Theodore Ts'o <tytso@....edu>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Coly Li <colyli@...e.de>, Filipe Manana <fdmanana@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Ming Lei <ming.lei@...hat.com>
Subject: [PATCH V7 15/24] fs/buffer.c: use bvec iterator to truncate the bio

Once multipage bvec is enabled, the last bvec may include more than one
page, this patch use bvec_last_segment() to truncate the bio.

Signed-off-by: Ming Lei <ming.lei@...hat.com>
---
 fs/buffer.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index cabc045f483d..0660b7813315 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3021,7 +3021,10 @@ void guard_bio_eod(int op, struct bio *bio)
 
 	/* ..and clear the end of the buffer for reads */
 	if (op == REQ_OP_READ) {
-		zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len,
+		struct bio_vec bv;
+
+		bvec_last_segment(bvec, &bv);
+		zero_user(bv.bv_page, bv.bv_offset + bv.bv_len,
 				truncated_bytes);
 	}
 }
-- 
2.9.5