On Wed, Jun 8, 2022 at 3:29 AM Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx> wrote: > > On lunedì 6 giugno 2022 17:03:05 CEST Hsin-Yi Wang 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. > > - 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); > > + } > > Hi Hsin-Yi, > > kmap_atomic() shouldn't be used in new code, unless there are special > reasons that I am not able to spot here. > > Why not use kmap_local_page(), preferably via memzero_page? Right, these can be replaced with kmap_local_page(pages[nr_pages - 1], bytes, PAGE_SIZE - bytes); Thanks for the suggestion. > > Thanks, > > Fabio > > > + > > + 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 > > > > > > > > > >
