From: Pavel Begunkov <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>,
Christoph Hellwig <[email protected]>,
Matthew Wilcox <[email protected]>,
Ming Lei <[email protected]>,
Johannes Weiner <[email protected]>,
Alexander Viro <[email protected]>,
"Darrick J . Wong" <[email protected]>,
"Martin K . Petersen" <[email protected]>,
Jonathan Corbet <[email protected]>,
[email protected], [email protected],
[email protected], [email protected],
[email protected], [email protected],
[email protected]
Subject: [PATCH v2 1/7] splice: don't generate zero-len segement bvecs
Date: Sat, 2 Jan 2021 15:17:33 +0000 [thread overview]
Message-ID: <ca14f80bf5156d83b38f543be2b9434a571474c9.1609461359.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>
iter_file_splice_write() may spawn bvec segments with zero-length. In
preparation for prohibiting them, filter out by hand at splice level.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/splice.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 866d5c2367b2..7299330c3270 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -644,7 +644,6 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
ret = splice_from_pipe_next(pipe, &sd);
if (ret <= 0)
break;
-
if (unlikely(nbufs < pipe->max_usage)) {
kfree(array);
nbufs = pipe->max_usage;
@@ -662,12 +661,13 @@ 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;
+ if (!this_len)
+ continue;
+ this_len = min(this_len, left);
ret = pipe_buf_confirm(pipe, buf);
if (unlikely(ret)) {
@@ -680,6 +680,7 @@ 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
next prev parent reply other threads:[~2021-01-02 15:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-02 15:17 [PATCH v2 0/7] no-copy bvec Pavel Begunkov
2021-01-02 15:17 ` Pavel Begunkov [this message]
2021-01-04 16:17 ` [PATCH v2 1/7] splice: don't generate zero-len segement bvecs Christoph Hellwig
2021-01-04 16:54 ` Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 2/7] bvec/iter: disallow zero-length segment bvecs Pavel Begunkov
2021-01-04 16:18 ` Christoph Hellwig
2021-01-04 16:37 ` Matthew Wilcox
2021-01-04 17:23 ` Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 3/7] block/psi: remove PSI annotations from direct IO Pavel Begunkov
2021-01-04 16:45 ` Christoph Hellwig
2021-01-02 15:17 ` [PATCH v2 4/7] target/file: allocate the bvec array as part of struct target_core_file_cmd Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 5/7] iov_iter: optimise bvec iov_iter_advance() Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 6/7] bio: add a helper calculating nr segments to alloc Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 7/7] bio: don't copy bvec for direct IO Pavel Begunkov
2021-01-04 16:20 ` Christoph Hellwig
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