diff options
| -rw-r--r-- | fs/splice.c | 95 |
1 files changed, 65 insertions, 30 deletions
diff --git a/fs/splice.c b/fs/splice.c index dc205f643090..a46ddd28561e 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -279,7 +279,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, pgoff_t index, end_index; loff_t isize; size_t total_len; - int error; + int error, page_nr; struct splice_pipe_desc spd = { .pages = pages, .partial = partial, @@ -307,39 +307,67 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, */ error = 0; total_len = 0; - for (spd.nr_pages = 0; spd.nr_pages < nr_pages; spd.nr_pages++, index++) { - unsigned int this_len; - if (!len) - break; + /* + * Lookup the (hopefully) full range of pages we need. + */ + spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); + /* + * If find_get_pages_contig() returned fewer pages than we needed, + * allocate the rest. + */ + index += spd.nr_pages; + while (spd.nr_pages < nr_pages) { /* - * this_len is the max we'll use from this page - */ - this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); -find_page: - /* - * lookup the page for this index + * 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 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_mask(mapping)); + mapping_gfp_mask(mapping)); if (unlikely(error)) { page_cache_release(page); break; } - - goto readpage; + /* + * add_to_page_cache() locks the page, unlock it + * to avoid convoluting the logic below even more. + */ + unlock_page(page); } + 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_CACHE_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_CACHE_SIZE - loff); + page = pages[page_nr]; + /* * If the page isn't uptodate, we may need to start io on it */ @@ -360,7 +388,6 @@ find_page: */ if (!page->mapping) { unlock_page(page); - page_cache_release(page); break; } /* @@ -371,16 +398,20 @@ find_page: goto fill_it; } -readpage: /* * need to read in the page */ error = mapping->a_ops->readpage(in, page); - if (unlikely(error)) { - page_cache_release(page); + /* + * We really should re-lookup the page here, + * but it complicates things a lot. Instead + * lets just do what we already stored, and + * we'll get it the next time we are called. + */ if (error == AOP_TRUNCATED_PAGE) - goto find_page; + error = 0; + break; } @@ -389,10 +420,8 @@ readpage: */ isize = i_size_read(mapping->host); end_index = (isize - 1) >> PAGE_CACHE_SHIFT; - if (unlikely(!isize || index > end_index)) { - page_cache_release(page); + if (unlikely(!isize || index > end_index)) break; - } /* * if this is the last page, see if we need to shrink @@ -400,27 +429,33 @@ readpage: */ if (end_index == index) { loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK); - if (total_len + loff > isize) { - page_cache_release(page); + if (total_len + loff > isize) break; - } /* * force quit after adding this page */ - nr_pages = spd.nr_pages; + len = this_len; this_len = min(this_len, loff); loff = 0; } } fill_it: - pages[spd.nr_pages] = page; - partial[spd.nr_pages].offset = loff; - partial[spd.nr_pages].len = this_len; + partial[page_nr].offset = loff; + partial[page_nr].len = this_len; len -= this_len; total_len += this_len; loff = 0; + spd.nr_pages++; + index++; } + /* + * Release any pages at the end, if we quit early. 'i' is how far + * we got, 'nr_pages' is how many pages are in the map. + */ + while (page_nr < nr_pages) + page_cache_release(pages[page_nr++]); + if (spd.nr_pages) return splice_to_pipe(pipe, &spd); |