[PATCH v3 1/7] splice: don't generate zero-len segement bvecs
From: Pavel Begunkov <asml.silence@gmail.com>
Date: 2021-01-09 16:08:21
Also in:
linux-block, linux-doc, linux-fsdevel, linux-scsi, linux-xfs, lkml, target-devel
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
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: Christoph Hellwig <hch@lst.de> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- fs/splice.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 866d5c2367b2..474fb8b5562a 100644
--- a/fs/splice.c
+++ b/fs/splice.c@@ -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);
--
2.24.0