The patch titled
Subject: squashfs: implement readahead
has been added to the -mm mm-nonmm-unstable branch. Its filename is
squashfs-implement-readahead.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/squashfs-implement-readahead.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
Subject: squashfs: implement readahead
Date: Mon, 13 Jun 2022 16:28:02 +0800
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.
Link: https://lkml.kernel.org/r/20220613082802.1301238-4-hsinyi@xxxxxxxxxxxx
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: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Hou Tao <houtao1@xxxxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Miao Xie <miaoxie@xxxxxxxxxx>
Cc: Zhang Yi <yi.zhang@xxxxxxxxxx>
Cc: Zheng Liang <zhengliang6@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/squashfs/file.c | 92 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 91 insertions(+), 1 deletion(-)
--- a/fs/squashfs/file.c~squashfs-implement-readahead
+++ a/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 +496,96 @@ out:
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;
+
+ 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;
+
+ actor = squashfs_page_actor_init_special(msblk, pages, nr_pages,
+ expected);
+ if (!actor)
+ goto skip_pages;
+
+ res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
+
+ kfree(actor);
+
+ if (res == expected) {
+ int bytes;
+
+ /* Last page (if present) may have trailing bytes not filled */
+ bytes = res % PAGE_SIZE;
+ if (pages[nr_pages - 1]->index == file_end && bytes)
+ memzero_page(pages[nr_pages - 1], bytes,
+ PAGE_SIZE - bytes);
+
+ 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(pages);
+ return;
+
+skip_pages:
+ for (i = 0; i < nr_pages; i++) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ }
+ kfree(pages);
+}
const struct address_space_operations squashfs_aops = {
- .read_folio = squashfs_read_folio
+ .read_folio = squashfs_read_folio,
+ .readahead = squashfs_readahead
};
_
Patches currently in -mm which might be from hsinyi@xxxxxxxxxxxx are
revert-squashfs-provide-backing_dev_info-in-order-to-disable-read-ahead.patch
squashfs-implement-readahead.patch
