[V10,06/19] fs/buffer.c: use bvec iterator to truncate the bio

Commit Message

Ming Lei Nov. 15, 2018, 8:52 a.m. UTC

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: Dave Chinner <[e-mail]>
Cc: Kent Overstreet <[e-mail]>
Cc: Mike Snitzer <[e-mail]>
Cc: [e-mail]
Cc: Alexander Viro <[e-mail]>
Cc: [e-mail]
Cc: Shaohua Li <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: David Sterba <[e-mail]>
Cc: [e-mail]
Cc: Darrick J. Wong <[e-mail]>
Cc: [e-mail]
Cc: Gao Xiang <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Theodore Ts'o <[e-mail]>
Cc: [e-mail]
Cc: Coly Li <[e-mail]>
Cc: [e-mail]
Cc: Boaz Harrosh <[e-mail]>
Cc: Bob Peterson <[e-mail]>
Cc: [e-mail]
Signed-off-by: Ming Lei <[e-mail]>
---
 fs/buffer.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Omar Sandoval Nov. 16, 2018, 12:20 a.m. UTC | #1

On Thu, Nov 15, 2018 at 04:52:53PM +0800, Ming Lei wrote:
> 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: Dave Chinner <[e-mail]>
> Cc: Kent Overstreet <[e-mail]>
> Cc: Mike Snitzer <[e-mail]>
> Cc: [e-mail]
> Cc: Alexander Viro <[e-mail]>
> Cc: [e-mail]
> Cc: Shaohua Li <[e-mail]>
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: David Sterba <[e-mail]>
> Cc: [e-mail]
> Cc: Darrick J. Wong <[e-mail]>
> Cc: [e-mail]
> Cc: Gao Xiang <[e-mail]>
> Cc: Christoph Hellwig <[e-mail]>
> Cc: Theodore Ts'o <[e-mail]>
> Cc: [e-mail]
> Cc: Coly Li <[e-mail]>
> Cc: [e-mail]
> Cc: Boaz Harrosh <[e-mail]>
> Cc: Bob Peterson <[e-mail]>
> Cc: [e-mail]

Reviewed-by: Omar Sandoval <[e-mail]>

> Signed-off-by: Ming Lei <[e-mail]>
> ---
>  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
>

Christoph Hellwig Nov. 16, 2018, 1:36 p.m. UTC | #2

Looks fine,

Reviewed-by: Christoph Hellwig <[e-mail]>

Patch

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);
 	}
 }