Commit 39157c51 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jialin Zhang
Browse files

splice: don't generate zero-len segement bvecs 

mainline inclusion
from mainline-v5.12-rc1
commit 0f1d344f
category: bugfix
bugzilla: 188445,https://gitee.com/openeuler/kernel/issues/I6J5NZ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0f1d344feb534555a0dcd0beafb7211a37c5355e



--------------------------------

iter_file_splice_write() may spawn bvec segments with zero-length. In
preparation for prohibiting them, filter out by hand at splice level.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarYang Erkun <yangerkun@huawei.com>
Reviewed-by: default avatarZhang Yi <yi.zhang@huawei.com>
Signed-off-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
parent 4c7c6c0d

fs/splice.c

+6 −3
Original line number Diff line number Diff line
@@ -662,12 +662,14 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, 


		/* build the vector */

		left = sd.total_len;

		for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++, n++) {

		for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) {

			struct pipe_buffer *buf = &pipe->bufs[tail & mask];

			size_t this_len = buf->len;



			if (this_len > left)

				this_len = left;

			/* zero-length bvecs are not supported, skip them */

			if (!this_len)

				continue;

			this_len = min(this_len, left);



			ret = pipe_buf_confirm(pipe, buf);

			if (unlikely(ret)) {
@@ -680,6 +682,7 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, 
			array[n].bv_len = this_len;

			array[n].bv_offset = buf->offset;

			left -= this_len;

			n++;

		}



		iov_iter_bvec(&from, WRITE, array, n, sd.total_len - left);