switch generic_file_splice_read() to use of ->read_iter()
... and kill the ->splice_read() instances that can be switched to it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/splice.c b/fs/splice.c
index 589a1d5..58c322a 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -281,207 +281,6 @@
kfree(spd->partial);
}
-static int
-__generic_file_splice_read(struct file *in, loff_t *ppos,
- struct pipe_inode_info *pipe, size_t len,
- unsigned int flags)
-{
- struct address_space *mapping = in->f_mapping;
- unsigned int loff, nr_pages, req_pages;
- struct page *pages[PIPE_DEF_BUFFERS];
- struct partial_page partial[PIPE_DEF_BUFFERS];
- struct page *page;
- pgoff_t index, end_index;
- loff_t isize;
- int error, page_nr;
- struct splice_pipe_desc spd = {
- .pages = pages,
- .partial = partial,
- .nr_pages_max = PIPE_DEF_BUFFERS,
- .flags = flags,
- .ops = &page_cache_pipe_buf_ops,
- .spd_release = spd_release_page,
- };
-
- if (splice_grow_spd(pipe, &spd))
- return -ENOMEM;
-
- index = *ppos >> PAGE_SHIFT;
- loff = *ppos & ~PAGE_MASK;
- req_pages = (len + loff + PAGE_SIZE - 1) >> PAGE_SHIFT;
- nr_pages = min(req_pages, spd.nr_pages_max);
-
- /*
- * Lookup the (hopefully) full range of pages we need.
- */
- spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages);
- index += spd.nr_pages;
-
- /*
- * If find_get_pages_contig() returned fewer pages than we needed,
- * readahead/allocate the rest and fill in the holes.
- */
- if (spd.nr_pages < nr_pages)
- page_cache_sync_readahead(mapping, &in->f_ra, in,
- index, req_pages - spd.nr_pages);
-
- error = 0;
- while (spd.nr_pages < nr_pages) {
- /*
- * Page could be there, find_get_pages_contig() breaks on
- * the first hole.
- */
- page = find_get_page(mapping, index);
- if (!page) {
- /*
- * page didn't exist, allocate one.
- */
- page = page_cache_alloc_cold(mapping);
- if (!page)
- break;
-
- error = add_to_page_cache_lru(page, mapping, index,
- mapping_gfp_constraint(mapping, GFP_KERNEL));
- if (unlikely(error)) {
- put_page(page);
- if (error == -EEXIST)
- continue;
- break;
- }
- /*
- * add_to_page_cache() locks the page, unlock it
- * to avoid convoluting the logic below even more.
- */
- unlock_page(page);
- }
-
- spd.pages[spd.nr_pages++] = page;
- index++;
- }
-
- /*
- * Now loop over the map and see if we need to start IO on any
- * pages, fill in the partial map, etc.
- */
- index = *ppos >> PAGE_SHIFT;
- nr_pages = spd.nr_pages;
- spd.nr_pages = 0;
- for (page_nr = 0; page_nr < nr_pages; page_nr++) {
- unsigned int this_len;
-
- if (!len)
- break;
-
- /*
- * this_len is the max we'll use from this page
- */
- this_len = min_t(unsigned long, len, PAGE_SIZE - loff);
- page = spd.pages[page_nr];
-
- if (PageReadahead(page))
- page_cache_async_readahead(mapping, &in->f_ra, in,
- page, index, req_pages - page_nr);
-
- /*
- * If the page isn't uptodate, we may need to start io on it
- */
- if (!PageUptodate(page)) {
- lock_page(page);
-
- /*
- * Page was truncated, or invalidated by the
- * filesystem. Redo the find/create, but this time the
- * page is kept locked, so there's no chance of another
- * race with truncate/invalidate.
- */
- if (!page->mapping) {
- unlock_page(page);
-retry_lookup:
- page = find_or_create_page(mapping, index,
- mapping_gfp_mask(mapping));
-
- if (!page) {
- error = -ENOMEM;
- break;
- }
- put_page(spd.pages[page_nr]);
- spd.pages[page_nr] = page;
- }
- /*
- * page was already under io and is now done, great
- */
- if (PageUptodate(page)) {
- unlock_page(page);
- goto fill_it;
- }
-
- /*
- * need to read in the page
- */
- error = mapping->a_ops->readpage(in, page);
- if (unlikely(error)) {
- /*
- * Re-lookup the page
- */
- if (error == AOP_TRUNCATED_PAGE)
- goto retry_lookup;
-
- break;
- }
- }
-fill_it:
- /*
- * i_size must be checked after PageUptodate.
- */
- isize = i_size_read(mapping->host);
- end_index = (isize - 1) >> PAGE_SHIFT;
- if (unlikely(!isize || index > end_index))
- break;
-
- /*
- * if this is the last page, see if we need to shrink
- * the length and stop
- */
- if (end_index == index) {
- unsigned int plen;
-
- /*
- * max good bytes in this page
- */
- plen = ((isize - 1) & ~PAGE_MASK) + 1;
- if (plen <= loff)
- break;
-
- /*
- * force quit after adding this page
- */
- this_len = min(this_len, plen - loff);
- len = this_len;
- }
-
- spd.partial[page_nr].offset = loff;
- spd.partial[page_nr].len = this_len;
- len -= this_len;
- loff = 0;
- spd.nr_pages++;
- index++;
- }
-
- /*
- * Release any pages at the end, if we quit early. 'page_nr' is how far
- * we got, 'nr_pages' is how many pages are in the map.
- */
- while (page_nr < nr_pages)
- put_page(spd.pages[page_nr++]);
- in->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
-
- if (spd.nr_pages)
- error = splice_to_pipe(pipe, &spd);
-
- splice_shrink_spd(&spd);
- return error;
-}
-
/**
* generic_file_splice_read - splice data from file to a pipe
* @in: file to splice from
@@ -492,32 +291,46 @@
*
* Description:
* Will read pages from given file and fill them into a pipe. Can be
- * used as long as the address_space operations for the source implements
- * a readpage() hook.
+ * used as long as it has more or less sane ->read_iter().
*
*/
ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
- loff_t isize, left;
- int ret;
-
- if (IS_DAX(in->f_mapping->host))
- return default_file_splice_read(in, ppos, pipe, len, flags);
+ struct iov_iter to;
+ struct kiocb kiocb;
+ loff_t isize;
+ int idx, ret;
isize = i_size_read(in->f_mapping->host);
if (unlikely(*ppos >= isize))
return 0;
- left = isize - *ppos;
- if (unlikely(left < len))
- len = left;
-
- ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
+ iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len);
+ idx = to.idx;
+ init_sync_kiocb(&kiocb, in);
+ kiocb.ki_pos = *ppos;
+ ret = in->f_op->read_iter(&kiocb, &to);
if (ret > 0) {
- *ppos += ret;
+ *ppos = kiocb.ki_pos;
file_accessed(in);
+ } else if (ret < 0) {
+ if (WARN_ON(to.idx != idx || to.iov_offset)) {
+ /*
+ * a bogus ->read_iter() has copied something and still
+ * returned an error instead of a short read.
+ */
+ to.idx = idx;
+ to.iov_offset = 0;
+ iov_iter_advance(&to, 0); /* to free what was emitted */
+ }
+ /*
+ * callers of ->splice_read() expect -EAGAIN on
+ * "can't put anything in there", rather than -EFAULT.
+ */
+ if (ret == -EFAULT)
+ ret = -EAGAIN;
}
return ret;
@@ -580,7 +393,7 @@
}
EXPORT_SYMBOL(kernel_write);
-ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
+static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
@@ -675,7 +488,6 @@
res = error;
goto shrink_ret;
}
-EXPORT_SYMBOL(default_file_splice_read);
/*
* Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'