From: Hsin-Yi Wang <hsinyi@chromium.org>
To: Phillip Lougher <phillip@squashfs.org.uk>,
Matthew Wilcox <willy@infradead.org>,
Xiongwei Song <Xiongwei.Song@windriver.com>
Cc: Zheng Liang <zhengliang6@huawei.com>,
Zhang Yi <yi.zhang@huawei.com>, Hou Tao <houtao1@huawei.com>,
Miao Xie <miaoxie@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm @ kvack . org" <linux-mm@kvack.org>,
"squashfs-devel @ lists . sourceforge . net"
<squashfs-devel@lists.sourceforge.net>,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 3/3] squashfs: implement readahead
Date: Tue, 17 May 2022 16:26:54 +0800 [thread overview]
Message-ID: <20220517082650.2005840-4-hsinyi@chromium.org> (raw)
In-Reply-To: <20220517082650.2005840-1-hsinyi@chromium.org>
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.
Otherwise pages will be marked as uptodate. The unhandled pages will be
updated by readpage later.
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reported-by: Matthew Wilcox <willy@infradead.org>
Reported-by: Phillip Lougher <phillip@squashfs.org.uk>
Reported-by: Xiongwei Song <sxwjean@gmail.com>
---
v1->v2: remove unused check on readahead_expand().
v1: https://lore.kernel.org/lkml/20220516105100.1412740-3-hsinyi@chromium.org/
---
fs/squashfs/file.c | 77 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 76 insertions(+), 1 deletion(-)
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index a8e495d8eb86..e10a55c5b1eb 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 +496,81 @@ 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;
+ int 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 (;;) {
+ 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;
+
+ 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 >= 0)
+ 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
};
--
2.36.0.550.gb090851708-goog
next prev parent reply other threads:[~2022-05-17 8:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-17 8:26 [PATCH v2 0/3] Implement readahead for squashfs Hsin-Yi Wang
2022-05-17 8:26 ` [PATCH v2 1/3] Revert "squashfs: provide backing_dev_info in order to disable read-ahead" Hsin-Yi Wang
2022-05-17 9:15 ` Xiongwei Song
2022-05-17 8:26 ` [PATCH v2 2/3] squashfs: always build "file direct" version of page actor Hsin-Yi Wang
2022-05-17 8:26 ` Hsin-Yi Wang [this message]
2022-05-17 9:16 ` [PATCH v2 3/3] squashfs: implement readahead Xiongwei Song
2022-05-19 7:56 ` Hsin-Yi Wang
2022-05-19 8:09 ` Hsin-Yi Wang
2022-05-20 3:02 ` Phillip Lougher
2022-05-20 7:38 ` Hsin-Yi Wang
2022-05-20 20:21 ` Phillip Lougher
2022-05-23 7:00 ` Hsin-Yi Wang
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