linux-kernel - [PATCH V8 06/18] fs/buffer.c: use bvec iterator to truncate the bio

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Message-Id: <20181109162610.18981-7-ming.lei@redhat.com>
Date:   Sat, 10 Nov 2018 00:25:58 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ming Lei <ming.lei@...hat.com>, Christoph Hellwig <hch@....de>,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH V8 06/18] fs/buffer.c: use bvec iterator to truncate the bio

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

Cc: Christoph Hellwig <hch@....de>
Cc: linux-fsdevel@...r.kernel.org
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 1286c2b95498..fa37ad52e962 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3032,7 +3032,10 @@ 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