On Mon, May 23, 2022 at 3:00 PM Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx> wrote: > > 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 or not enough in a > 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> > --- Kindly ping on the thread. Conversations on v2: https://patchwork.kernel.org/project/linux-mm/patch/20220517082650.2005840-4-hsinyi@xxxxxxxxxxxx/#24869037 This version mainly addressed the error handling. Thanks > v2->v3: Add checks on > - decompressed block size. > - fill zeros if the last page is not a full page. > > 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 | 91 +++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 90 insertions(+), 1 deletion(-) > > diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c > index a8e495d8eb86..c311fc685fe4 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 +496,95 @@ 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; > + size_t 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; > + u64 block = 0; > + int bsize, res, i, index, bytes, expected; > + int file_end = i_size_read(inode) >> msblk->block_log; > + unsigned int max_pages = 1UL << shift; > + void *pageaddr; > + > + 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 (;;) { > + nr_pages = __readahead_batch(ractl, pages, max_pages); > + if (!nr_pages) > + break; > + > + if (readahead_pos(ractl) >= i_size_read(inode) || > + nr_pages < max_pages) > + 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; > + > + res = squashfs_read_data(inode->i_sb, block, bsize, NULL, > + actor); > + > + if (res == expected) { > + /* Last page may have trailing bytes not filled */ > + bytes = res % PAGE_SIZE; > + if (bytes) { > + pageaddr = kmap_atomic(pages[nr_pages - 1]); > + memset(pageaddr + bytes, 0, PAGE_SIZE - bytes); > + kunmap_atomic(pageaddr); > + } > + > + for (i = 0; i < nr_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 > }; > -- > 2.36.1.124.g0e6072fb45-goog >
