All their callers are next to each other; all of them
want the total amount of pages and, possibly, the
offset in the partial final buffer.
Combine into a new helper (pipe_npages()), fix the
bogosity in pipe_space_for_user(), while we are at it.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
include/linux/pipe_fs_i.h | 20 ------------------
lib/iov_iter.c | 44 +++++++++++++++++----------------------
2 files changed, 19 insertions(+), 45 deletions(-)
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 4ea496924106..6cb65df3e3ba 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -156,26 +156,6 @@ static inline bool pipe_full(unsigned int head, unsigned int tail,
return pipe_occupancy(head, tail) >= limit;
}
-/**
- * pipe_space_for_user - Return number of slots available to userspace
- * @head: The pipe ring head pointer
- * @tail: The pipe ring tail pointer
- * @pipe: The pipe info structure
- */
-static inline unsigned int pipe_space_for_user(unsigned int head, unsigned int tail,
- struct pipe_inode_info *pipe)
-{
- unsigned int p_occupancy, p_space;
-
- p_occupancy = pipe_occupancy(head, tail);
- if (p_occupancy >= pipe->max_usage)
- return 0;
- p_space = pipe->ring_size - p_occupancy;
- if (p_space > pipe->max_usage)
- p_space = pipe->max_usage;
- return p_space;
-}
-
/**
* pipe_buf_get - get a reference to a pipe_buffer
* @pipe: the pipe that the buffer belongs to
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 27ad2ef93dbc..30f4158382d6 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -435,18 +435,20 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
}
EXPORT_SYMBOL(iov_iter_init);
-static inline void data_start(const struct iov_iter *i,
- unsigned int *iter_headp, size_t *offp)
+// returns the offset in partial buffer (if any)
+static inline unsigned int pipe_npages(const struct iov_iter *i, int *npages)
{
+ struct pipe_inode_info *pipe = i->pipe;
+ int used = pipe->head - pipe->tail;
int off = i->last_offset;
+ *npages = max((int)pipe->max_usage - used, 0);
+
if (off > 0 && off < PAGE_SIZE) { // anon and not full
- *iter_headp = i->pipe->head - 1;
- *offp = off;
- } else {
- *iter_headp = i->pipe->head;
- *offp = 0;
+ (*npages)++;
+ return off;
}
+ return 0;
}
static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
@@ -1221,18 +1223,16 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
- unsigned int iter_head, npages;
+ unsigned int npages, off;
size_t capacity;
if (!sanity(i))
return -EFAULT;
- data_start(i, &iter_head, start);
- /* Amount of free space: some of this one + all after this one */
- npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
- capacity = min(npages, maxpages) * PAGE_SIZE - *start;
+ *start = off = pipe_npages(i, &npages);
+ capacity = min(npages, maxpages) * PAGE_SIZE - off;
- return __pipe_get_pages(i, min(maxsize, capacity), pages, *start);
+ return __pipe_get_pages(i, min(maxsize, capacity), pages, off);
}
static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
@@ -1411,24 +1411,22 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
size_t *start)
{
struct page **p;
- unsigned int iter_head, npages;
+ unsigned int npages, off;
ssize_t n;
if (!sanity(i))
return -EFAULT;
- data_start(i, &iter_head, start);
- /* Amount of free space: some of this one + all after this one */
- npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
- n = npages * PAGE_SIZE - *start;
+ *start = off = pipe_npages(i, &npages);
+ n = npages * PAGE_SIZE - off;
if (maxsize > n)
maxsize = n;
else
- npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
+ npages = DIV_ROUND_UP(maxsize + off, PAGE_SIZE);
p = get_pages_array(npages);
if (!p)
return -ENOMEM;
- n = __pipe_get_pages(i, maxsize, p, *start);
+ n = __pipe_get_pages(i, maxsize, p, off);
if (n > 0)
*pages = p;
else
@@ -1653,16 +1651,12 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
if (iov_iter_is_bvec(i))
return bvec_npages(i, maxpages);
if (iov_iter_is_pipe(i)) {
- unsigned int iter_head;
int npages;
- size_t off;
if (!sanity(i))
return 0;
- data_start(i, &iter_head, &off);
- /* some of this one + all after this one */
- npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
+ pipe_npages(i, &npages);
return min(npages, maxpages);
}
if (iov_iter_is_xarray(i)) {
--
2.30.2
