[PATCH v2 4/4] fs/splice: Use pipe_buf() helper to retrieve pipe buffer

K Prateek Nayak
2025-03-07T05:30:54Z

Use pipe_buf() helper to retrieve the pipe buffer throughout the file
replacing the open-coded the logic.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
---
Changelog:

RFC v1..v2:

o New patch.
---
fs/splice.c | 40 ++++++++++++++--------------------------
1 file changed, 14 insertions(+), 26 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index 23fa5561b944..90d464241f15 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -200,7 +200,6 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
unsigned int spd_pages = spd->nr_pages;
unsigned int tail = pipe->tail;
unsigned int head = pipe->head;
- unsigned int mask = pipe->ring_size - 1;
ssize_t ret = 0;
int page_nr = 0;

@@ -214,7 +213,7 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
}

while (!pipe_full(head, tail, pipe->max_usage)) {
- struct pipe_buffer *buf = &pipe->bufs[head & mask];
+ struct pipe_buffer *buf = pipe_buf(pipe, head);

buf->page = spd->pages[page_nr];
buf->offset = spd->partial[page_nr].offset;
@@ -247,7 +246,6 @@ ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
{
unsigned int head = pipe->head;
unsigned int tail = pipe->tail;
- unsigned int mask = pipe->ring_size - 1;
int ret;

if (unlikely(!pipe->readers)) {
@@ -256,7 +254,7 @@ ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
} else if (pipe_full(head, tail, pipe->max_usage)) {
ret = -EAGAIN;
} else {
- pipe->bufs[head & mask] = *buf;
+ *pipe_buf(pipe, head) = *buf;
pipe->head = head + 1;
return buf->len;
}
@@ -447,11 +445,10 @@ static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_des
{
unsigned int head = pipe->head;
unsigned int tail = pipe->tail;
- unsigned int mask = pipe->ring_size - 1;
int ret;

while (!pipe_empty(head, tail)) {
- struct pipe_buffer *buf = &pipe->bufs[tail & mask];
+ struct pipe_buffer *buf = pipe_buf(pipe, tail);

sd->len = buf->len;
if (sd->len > sd->total_len)
@@ -495,8 +492,7 @@ static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_des
static inline bool eat_empty_buffer(struct pipe_inode_info *pipe)
{
unsigned int tail = pipe->tail;
- unsigned int mask = pipe->ring_size - 1;
- struct pipe_buffer *buf = &pipe->bufs[tail & mask];
+ struct pipe_buffer *buf = pipe_buf(pipe, tail);

if (unlikely(!buf->len)) {
pipe_buf_release(pipe, buf);
@@ -690,7 +686,7 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
while (sd.total_len) {
struct kiocb kiocb;
struct iov_iter from;
- unsigned int head, tail, mask;
+ unsigned int head, tail;
size_t left;
int n;

@@ -711,12 +707,11 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,

head = pipe->head;
tail = pipe->tail;
- mask = pipe->ring_size - 1;

/* build the vector */
left = sd.total_len;
for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) {
- struct pipe_buffer *buf = &pipe->bufs[tail & mask];
+ struct pipe_buffer *buf = pipe_buf(pipe, tail);
size_t this_len = buf->len;

/* zero-length bvecs are not supported, skip them */
@@ -752,7 +747,7 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
/* dismiss the fully eaten buffers, adjust the partial one */
tail = pipe->tail;
while (ret) {
- struct pipe_buffer *buf = &pipe->bufs[tail & mask];
+ struct pipe_buffer *buf = pipe_buf(pipe, tail);
if (ret >= buf->len) {
ret -= buf->len;
buf->len = 0;
@@ -809,7 +804,7 @@ ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out,
pipe_lock(pipe);

while (len > 0) {
- unsigned int head, tail, mask, bc = 0;
+ unsigned int head, tail, bc = 0;
size_t remain = len;

/*
@@ -846,10 +841,9 @@ ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out,

head = pipe->head;
tail = pipe->tail;
- mask = pipe->ring_size - 1;

while (!pipe_empty(head, tail)) {
- struct pipe_buffer *buf = &pipe->bufs[tail & mask];
+ struct pipe_buffer *buf = pipe_buf(pipe, tail);
size_t seg;

if (!buf->len) {
@@ -894,7 +888,7 @@ ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out,
len -= ret;
tail = pipe->tail;
while (ret > 0) {
- struct pipe_buffer *buf = &pipe->bufs[tail & mask];
+ struct pipe_buffer *buf = pipe_buf(pipe, tail);
size_t seg = min_t(size_t, ret, buf->len);

buf->offset += seg;
@@ -1725,7 +1719,6 @@ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
struct pipe_buffer *ibuf, *obuf;
unsigned int i_head, o_head;
unsigned int i_tail, o_tail;
- unsigned int i_mask, o_mask;
int ret = 0;
bool input_wakeup = false;

@@ -1747,9 +1740,7 @@ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
pipe_double_lock(ipipe, opipe);

i_tail = ipipe->tail;
- i_mask = ipipe->ring_size - 1;
o_head = opipe->head;
- o_mask = opipe->ring_size - 1;

do {
size_t o_len;
@@ -1792,8 +1783,8 @@ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
goto retry;
}

- ibuf = &ipipe->bufs[i_tail & i_mask];
- obuf = &opipe->bufs[o_head & o_mask];
+ ibuf = pipe_buf(ipipe, i_tail);
+ obuf = pipe_buf(opipe, o_head);

if (len >= ibuf->len) {
/*
@@ -1862,7 +1853,6 @@ static ssize_t link_pipe(struct pipe_inode_info *ipipe,
struct pipe_buffer *ibuf, *obuf;
unsigned int i_head, o_head;
unsigned int i_tail, o_tail;
- unsigned int i_mask, o_mask;
ssize_t ret = 0;

/*
@@ -1873,9 +1863,7 @@ static ssize_t link_pipe(struct pipe_inode_info *ipipe,
pipe_double_lock(ipipe, opipe);

i_tail = ipipe->tail;
- i_mask = ipipe->ring_size - 1;
o_head = opipe->head;
- o_mask = opipe->ring_size - 1;

do {
if (!opipe->readers) {
@@ -1896,8 +1884,8 @@ static ssize_t link_pipe(struct pipe_inode_info *ipipe,
pipe_full(o_head, o_tail, opipe->max_usage))
break;

- ibuf = &ipipe->bufs[i_tail & i_mask];
- obuf = &opipe->bufs[o_head & o_mask];
+ ibuf = pipe_buf(ipipe, i_tail);
+ obuf = pipe_buf(opipe, o_head);

/*
* Get a reference to this pipe buffer,
--
2.43.0