Implement readahead callback for squashfs. It will read datablocks which cover pages in readahead request. For a few cases it will not mark page as uptodate, including: - file end is 0. - zero filled blocks. - current batch of pages isn't in the same datablock. - decompressor error. Otherwise pages will be marked as uptodate. The unhandled pages will be updated by readpage later. Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> Signed-off-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx> Reported-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> Reported-by: Phillip Lougher <phillip@xxxxxxxxxxxxxxx> Reported-by: Xiongwei Song <Xiongwei.Song@xxxxxxxxxxxxx> Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- v4->v5: - Handle short file cases reported by Marek and Matthew. - Fix checkpatch error reported by Andrew. v4: https://lore.kernel.org/lkml/20220601103922.1338320-4-hsinyi@xxxxxxxxxxxx/ v3: https://lore.kernel.org/lkml/20220523065909.883444-4-hsinyi@xxxxxxxxxxxx/ v2: https://lore.kernel.org/lkml/20220517082650.2005840-4-hsinyi@xxxxxxxxxxxx/ v1: https://lore.kernel.org/lkml/20220516105100.1412740-3-hsinyi@xxxxxxxxxxxx/ --- fs/squashfs/file.c | 124 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 123 insertions(+), 1 deletion(-) diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c index a8e495d8eb86..fbd096cd15f4 100644 --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -39,6 +39,7 @@ #include "squashfs_fs_sb.h" #include "squashfs_fs_i.h" #include "squashfs.h" +#include "page_actor.h" /* * Locate cache slot in range [offset, index] for specified inode. If @@ -495,7 +496,128 @@ static int squashfs_read_folio(struct file *file, struct folio *folio) return 0; } +static void squashfs_readahead(struct readahead_control *ractl) +{ + struct inode *inode = ractl->mapping->host; + struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; + size_t mask = (1UL << msblk->block_log) - 1; + unsigned short shift = msblk->block_log - PAGE_SHIFT; + loff_t start = readahead_pos(ractl) & ~mask; + size_t len = readahead_length(ractl) + readahead_pos(ractl) - start; + struct squashfs_page_actor *actor; + unsigned int nr_pages = 0; + struct page **pages; + int i, file_end = i_size_read(inode) >> msblk->block_log; + unsigned int max_pages = 1UL << shift; + + readahead_expand(ractl, start, (len | mask) + 1); + + if (file_end == 0) + return; + + pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL); + if (!pages) + return; + + actor = squashfs_page_actor_init_special(pages, max_pages, 0); + if (!actor) + goto out; + + for (;;) { + pgoff_t index; + int res, bsize; + u64 block = 0; + unsigned int expected; + + nr_pages = __readahead_batch(ractl, pages, max_pages); + if (!nr_pages) + break; + + if (readahead_pos(ractl) >= i_size_read(inode)) + goto skip_pages; + + index = pages[0]->index >> shift; + if ((pages[nr_pages - 1]->index >> shift) != index) + goto skip_pages; + + expected = index == file_end ? + (i_size_read(inode) & (msblk->block_size - 1)) : + msblk->block_size; + + bsize = read_blocklist(inode, index, &block); + if (bsize == 0) + goto skip_pages; + + if (nr_pages < max_pages) { + struct squashfs_cache_entry *buffer; + unsigned int block_mask = max_pages - 1; + int offset = pages[0]->index - (pages[0]->index & ~block_mask); + + buffer = squashfs_get_datablock(inode->i_sb, block, + bsize); + if (buffer->error) { + squashfs_cache_put(buffer); + goto skip_pages; + } + + expected -= offset * PAGE_SIZE; + for (i = 0; i < nr_pages && expected > 0; i++, + expected -= PAGE_SIZE, offset++) { + int avail = min_t(int, expected, PAGE_SIZE); + + squashfs_fill_page(pages[i], buffer, + offset * PAGE_SIZE, avail); + unlock_page(pages[i]); + } + + squashfs_cache_put(buffer); + continue; + } + + res = squashfs_read_data(inode->i_sb, block, bsize, NULL, + actor); + + if (res == expected) { + int bytes; + + /* Last page may have trailing bytes not filled */ + bytes = res % PAGE_SIZE; + if (bytes) { + void *pageaddr; + + pageaddr = kmap_atomic(pages[nr_pages - 1]); + memset(pageaddr + bytes, 0, PAGE_SIZE - bytes); + kunmap_atomic(pageaddr); + } + + for (i = 0; i < nr_pages; i++) { + flush_dcache_page(pages[i]); + SetPageUptodate(pages[i]); + } + } + + for (i = 0; i < nr_pages; i++) { + unlock_page(pages[i]); + put_page(pages[i]); + } + } + + kfree(actor); + kfree(pages); + return; + +skip_pages: + for (i = 0; i < nr_pages; i++) { + unlock_page(pages[i]); + put_page(pages[i]); + } + + kfree(actor); +out: + kfree(pages); +} const struct address_space_operations squashfs_aops = { - .read_folio = squashfs_read_folio + .read_folio = squashfs_read_folio, + .readahead = squashfs_readahead }; -- 2.36.1.255.ge46751e96f-goog
