[PATCH v2 31/51] fs/buffer.c: use bvec iterator to truncate the bio

Ming Lei
2017-06-26T12:18:08Z

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

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
fs/buffer.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 1910f539770b..53b8a29f4525 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3055,8 +3055,7 @@ void guard_bio_eod(int op, struct bio *bio)
unsigned truncated_bytes;
/*
* It is safe to truncate the last bvec in the following way
- * even though multipage bvec is supported, but we need to
- * fix the parameters passed to zero_user().
+ * even though multipage bvec is supported.
*/
struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];

@@ -3085,7 +3084,10 @@ 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_get_last_page(bvec, &bv);
+ zero_user(bv.bv_page, bv.bv_offset + bv.bv_len,
truncated_bytes);
}
}
--
2.9.4