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unify pipe_get_pages() and pipe_get_pages_alloc() 

The differences between those two are
* pipe_get_pages() gets a non-NULL struct page ** value pointing to
preallocated array + array size.
* pipe_get_pages_alloc() gets an address of struct page ** variable that
contains NULL, allocates the array and (on success) stores its address in
that variable.

	Not hard to combine - always pass struct page ***, have
the previous pipe_get_pages_alloc() caller pass ~0U as cap for
array size.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-06-17 13:35:35 -04:00
parent c81ce28df5
commit acbdeb8320
1 changed files with 17 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
lib/iov_iter.c
View File

@ -1284,6 +1284,11 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
}
EXPORT_SYMBOL(iov_iter_gap_alignment);
static struct page **get_pages_array(size_t n)
{
return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
}
static inline ssize_t __pipe_get_pages(struct iov_iter *i,
size_t maxsize,
struct page **pages,
@ -1317,10 +1322,11 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i,
}
static ssize_t pipe_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
struct page ***pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
unsigned int npages, off;
struct page **p;
size_t capacity;
if (!sanity(i))
@ -1328,8 +1334,15 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
*start = off = pipe_npages(i, &npages);
capacity = min(npages, maxpages) * PAGE_SIZE - off;
maxsize = min(maxsize, capacity);
p = *pages;
if (!p) {
*pages = p = get_pages_array(DIV_ROUND_UP(maxsize + off, PAGE_SIZE));
if (!p)
return -ENOMEM;
}
return __pipe_get_pages(i, min(maxsize, capacity), pages, off);
return __pipe_get_pages(i, maxsize, p, off);
}
static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
@ -1475,41 +1488,13 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
return min_t(size_t, maxsize, n * PAGE_SIZE - *start);
}
if (iov_iter_is_pipe(i))
return pipe_get_pages(i, pages, maxsize, maxpages, start);
return pipe_get_pages(i, &pages, maxsize, maxpages, start);
if (iov_iter_is_xarray(i))
return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
return -EFAULT;
}
EXPORT_SYMBOL(iov_iter_get_pages);
static struct page **get_pages_array(size_t n)
{
return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
}
static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
struct page **p;
unsigned int npages, off;
ssize_t n;
if (!sanity(i))
return -EFAULT;
*start = off = pipe_npages(i, &npages);
n = npages * PAGE_SIZE - off;
if (maxsize > n)
maxsize = n;
else
npages = DIV_ROUND_UP(maxsize + off, PAGE_SIZE);
*pages = p = get_pages_array(npages);
if (!p)
return -ENOMEM;
return __pipe_get_pages(i, maxsize, p, off);
}
static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *_start_offset)
@ -1593,7 +1578,7 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
return min_t(size_t, maxsize, n * PAGE_SIZE - *start);
}
if (iov_iter_is_pipe(i))
return pipe_get_pages_alloc(i, pages, maxsize, start);
return pipe_get_pages(i, pages, maxsize, ~0U, start);
if (iov_iter_is_xarray(i))
return iter_xarray_get_pages_alloc(i, pages, maxsize, start);
return -EFAULT;