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splice: switch get_iovec_page_array() to iov_iter

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-09-17 20:25:06 -04:00
parent e7c3c64624
commit db85a9eb2e
1 changed files with 35 additions and 98 deletions
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133
fs/splice.c
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@ -1434,106 +1434,32 @@ static long do_splice(struct file *in, loff_t __user *off_in,
return -EINVAL;
}
/*
* Map an iov into an array of pages and offset/length tupples. With the
* partial_page structure, we can map several non-contiguous ranges into
* our ones pages[] map instead of splitting that operation into pieces.
* Could easily be exported as a generic helper for other users, in which
* case one would probably want to add a 'max_nr_pages' parameter as well.
*/
static int get_iovec_page_array(const struct iovec __user *iov,
unsigned int nr_vecs, struct page **pages,
struct partial_page *partial, bool aligned,
static int get_iovec_page_array(struct iov_iter *from,
struct page **pages,
struct partial_page *partial,
unsigned int pipe_buffers)
{
int buffers = 0, error = 0;
int buffers = 0;
while (iov_iter_count(from)) {
ssize_t copied;
size_t start;
while (nr_vecs) {
unsigned long off, npages;
struct iovec entry;
void __user *base;
size_t len;
int i;
copied = iov_iter_get_pages(from, pages + buffers, ~0UL,
pipe_buffers - buffers, &start);
if (copied <= 0)
return buffers ? buffers : copied;
error = -EFAULT;
if (copy_from_user(&entry, iov, sizeof(entry)))
break;
base = entry.iov_base;
len = entry.iov_len;
/*
* Sanity check this iovec. 0 read succeeds.
*/
error = 0;
if (unlikely(!len))
break;
error = -EFAULT;
if (!access_ok(VERIFY_READ, base, len))
break;
/*
* Get this base offset and number of pages, then map
* in the user pages.
*/
off = (unsigned long) base & ~PAGE_MASK;
/*
* If asked for alignment, the offset must be zero and the
* length a multiple of the PAGE_SIZE.
*/
error = -EINVAL;
if (aligned && (off || len & ~PAGE_MASK))
break;
npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (npages > pipe_buffers - buffers)
npages = pipe_buffers - buffers;
error = get_user_pages_fast((unsigned long)base, npages,
0, &pages[buffers]);
if (unlikely(error <= 0))
break;
/*
* Fill this contiguous range into the partial page map.
*/
for (i = 0; i < error; i++) {
const int plen = min_t(size_t, len, PAGE_SIZE - off);
partial[buffers].offset = off;
partial[buffers].len = plen;
off = 0;
len -= plen;
iov_iter_advance(from, copied);
while (copied) {
int size = min_t(int, copied, PAGE_SIZE - start);
partial[buffers].offset = start;
partial[buffers].len = size;
copied -= size;
start = 0;
buffers++;
}
/*
* We didn't complete this iov, stop here since it probably
* means we have to move some of this into a pipe to
* be able to continue.
*/
if (len)
break;
/*
* Don't continue if we mapped fewer pages than we asked for,
* or if we mapped the max number of pages that we have
* room for.
*/
if (error < npages || buffers == pipe_buffers)
break;
nr_vecs--;
iov++;
}
if (buffers)
return buffers;
return error;
return buffers;
}
static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
@ -1587,10 +1513,13 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
* as splice-from-memory, where the regular splice is splice-from-file (or
* to file). In both cases the output is a pipe, naturally.
*/
static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
unsigned long nr_segs, unsigned int flags)
{
struct pipe_inode_info *pipe;
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter from;
struct page *pages[PIPE_DEF_BUFFERS];
struct partial_page partial[PIPE_DEF_BUFFERS];
struct splice_pipe_desc spd = {
@ -1607,11 +1536,18 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
if (!pipe)
return -EBADF;
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
ret = import_iovec(WRITE, uiov, nr_segs,
ARRAY_SIZE(iovstack), &iov, &from);
if (ret < 0)
return ret;
spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
spd.partial, false,
if (splice_grow_spd(pipe, &spd)) {
kfree(iov);
return -ENOMEM;
}
spd.nr_pages = get_iovec_page_array(&from, spd.pages,
spd.partial,
spd.nr_pages_max);
if (spd.nr_pages <= 0)
ret = spd.nr_pages;
@ -1619,6 +1555,7 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
ret = splice_to_pipe(pipe, &spd);
splice_shrink_spd(&spd);
kfree(iov);
return ret;
}