diff options
| -rw-r--r-- | fs/splice.c | 99 | ||||
| -rw-r--r-- | include/linux/pagemap.h | 2 | ||||
| -rw-r--r-- | mm/filemap.c | 32 |
3 files changed, 101 insertions, 32 deletions
diff --git a/fs/splice.c b/fs/splice.c index 447ebc0a37f..a46ddd28561 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, @@ -299,47 +299,75 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, * read-ahead if this is a non-zero offset (we are likely doing small * chunk splice and the page is already there) for a single page. */ - if (!loff || spd.nr_pages > 1) - do_page_cache_readahead(mapping, in, index, spd.nr_pages); + if (!loff || nr_pages > 1) + page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages); /* * Now fill in the holes: */ 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); diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 9539efd4f7e..7a1af574ded 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -78,6 +78,8 @@ extern struct page * find_or_create_page(struct address_space *mapping, unsigned long index, gfp_t gfp_mask); unsigned find_get_pages(struct address_space *mapping, pgoff_t start, unsigned int nr_pages, struct page **pages); +unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, + unsigned int nr_pages, struct page **pages); unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, int tag, unsigned int nr_pages, struct page **pages); diff --git a/mm/filemap.c b/mm/filemap.c index 3ef20739e72..fd57442186c 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -697,6 +697,38 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start, return ret; } +/** + * find_get_pages_contig - gang contiguous pagecache lookup + * @mapping: The address_space to search + * @index: The starting page index + * @nr_pages: The maximum number of pages + * @pages: Where the resulting pages are placed + * + * find_get_pages_contig() works exactly like find_get_pages(), except + * that the returned number of pages are guaranteed to be contiguous. + * + * find_get_pages_contig() returns the number of pages which were found. + */ +unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, + unsigned int nr_pages, struct page **pages) +{ + unsigned int i; + unsigned int ret; + + read_lock_irq(&mapping->tree_lock); + ret = radix_tree_gang_lookup(&mapping->page_tree, + (void **)pages, index, nr_pages); + for (i = 0; i < ret; i++) { + if (pages[i]->mapping == NULL || pages[i]->index != index) + break; + + page_cache_get(pages[i]); + index++; + } + read_unlock_irq(&mapping->tree_lock); + return i; +} + /* * Like find_get_pages, except we only return pages which are tagged with * `tag'. We update *index to index the next page for the traversal. |