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ITER_PIPE: fold push_pipe() into __pipe_get_pages() 

Expand the only remaining call of push_pipe() (in
__pipe_get_pages()), combine it with the page-collecting loop there.

Note that the only reason it's not a loop doing append_pipe() is
that append_pipe() is advancing, while iov_iter_get_pages() is not.
As soon as it switches to saner semantics, this thing will switch
to using append_pipe().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-06-11 02:52:03 -04:00
parent 8fad7767ed
commit e3b42964f8
1 changed files with 25 additions and 55 deletions
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78
lib/iov_iter.c
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@ -450,46 +450,6 @@ static inline void data_start(const struct iov_iter *i,
*offp = off;
}
static size_t push_pipe(struct iov_iter *i, size_t size,
int *iter_headp, size_t *offp)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int iter_head;
size_t off;
ssize_t left;
if (unlikely(size > i->count))
size = i->count;
if (unlikely(!size))
return 0;
left = size;
data_start(i, &iter_head, &off);
*iter_headp = iter_head;
*offp = off;
if (off) {
struct pipe_buffer *buf = pipe_buf(pipe, iter_head);
left -= PAGE_SIZE - off;
if (left <= 0) {
buf->len += size;
return size;
}
buf->len = PAGE_SIZE;
}
while (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
struct page *page = push_anon(pipe,
min_t(ssize_t, left, PAGE_SIZE));
if (!page)
break;
left -= PAGE_SIZE;
if (left <= 0)
return size;
}
return size - left;
}
static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
struct iov_iter *i)
{
@ -1359,24 +1319,34 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i,
size_t maxsize,
struct page **pages,
int iter_head,
size_t *start)
size_t off)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_mask = pipe->ring_size - 1;
ssize_t n = push_pipe(i, maxsize, &iter_head, start);
if (!n)
return -EFAULT;
ssize_t left = maxsize;
maxsize = n;
n += *start;
while (n > 0) {
get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
iter_head++;
n -= PAGE_SIZE;
}
if (off) {
struct pipe_buffer *buf = pipe_buf(pipe, iter_head);
get_page(*pages++ = buf->page);
left -= PAGE_SIZE - off;
if (left <= 0) {
buf->len += maxsize;
return maxsize;
}
buf->len = PAGE_SIZE;
}
while (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
struct page *page = push_anon(pipe,
min_t(ssize_t, left, PAGE_SIZE));
if (!page)
break;
get_page(*pages++ = page);
left -= PAGE_SIZE;
if (left <= 0)
return maxsize;
}
return maxsize - left ? : -EFAULT;
}
static ssize_t pipe_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
@ -1393,7 +1363,7 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
capacity = min(npages, maxpages) * PAGE_SIZE - *start;
return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, *start);
}
static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
@ -1575,7 +1545,7 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
p = get_pages_array(npages);
if (!p)
return -ENOMEM;
n = __pipe_get_pages(i, maxsize, p, iter_head, start);
n = __pipe_get_pages(i, maxsize, p, iter_head, *start);
if (n > 0)
*pages = p;
else