The patch titled
Subject: Revert "squashfs: provide backing_dev_info in order to disable read-ahead"
has been added to the -mm mm-nonmm-unstable branch. Its filename is
revert-squashfs-provide-backing_dev_info-in-order-to-disable-read-ahead.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/revert-squashfs-provide-backing_dev_info-in-order-to-disable-read-ahead.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: Revert "squashfs: provide backing_dev_info in order to disable read-ahead"
Date: Mon, 6 Jun 2022 23:03:03 +0800
Patch series "Implement readahead for squashfs", v5.
Commit c1f6925e1091("mm: put readahead pages in cache earlier") requires
fs to implement readahead callback. Otherwise there will be a performance
regression.
Commit 9eec1d897139("squashfs: provide backing_dev_info in order to
disable read-ahead") mitigates the performance drop issue for squashfs by
closing readahead for it.
This series implements readahead callback for squashfs. The previous
discussion are in [1] and [2].
[1] https://lore.kernel.org/all/CAJMQK-g9G6KQmH-V=BRGX0swZji9Wxe_2c7ht-MMAapdFy2pXw@xxxxxxxxxxxxxx/T/
[2] https://lore.kernel.org/linux-mm/Yn5Yij9pRPCzDozt@xxxxxxxxxxxxxxxxxxxx/t/#m4af4473b94f98a4996cb11756b633a07e5e059d1
This patch (of 3):
This reverts commit 9eec1d897139e5d ("squashfs: provide backing_dev_info
in order to disable read-ahead").
Revert closing the readahead to squashfs since the readahead callback
for squashfs is implemented.
Link: https://lkml.kernel.org/r/20220606150305.1883410-1-hsinyi@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20220606150305.1883410-2-hsinyi@xxxxxxxxxxxx
Signed-off-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
Suggested-by: Xiongwei Song <Xiongwei.Song@xxxxxxxxxxxxx>
Cc: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Zheng Liang <zhengliang6@xxxxxxxxxx>
Cc: Zhang Yi <yi.zhang@xxxxxxxxxx>
Cc: Hou Tao <houtao1@xxxxxxxxxx>
Cc: Miao Xie <miaoxie@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/squashfs/super.c | 33 ---------------------------------
1 file changed, 33 deletions(-)
--- a/fs/squashfs/super.c~revert-squashfs-provide-backing_dev_info-in-order-to-disable-read-ahead
+++ a/fs/squashfs/super.c
@@ -29,7 +29,6 @@
#include <linux/module.h>
#include <linux/magic.h>
#include <linux/xattr.h>
-#include <linux/backing-dev.h>
#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
@@ -113,24 +112,6 @@ static const struct squashfs_decompresso
return decompressor;
}
-static int squashfs_bdi_init(struct super_block *sb)
-{
- int err;
- unsigned int major = MAJOR(sb->s_dev);
- unsigned int minor = MINOR(sb->s_dev);
-
- bdi_put(sb->s_bdi);
- sb->s_bdi = &noop_backing_dev_info;
-
- err = super_setup_bdi_name(sb, "squashfs_%u_%u", major, minor);
- if (err)
- return err;
-
- sb->s_bdi->ra_pages = 0;
- sb->s_bdi->io_pages = 0;
-
- return 0;
-}
static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
@@ -146,20 +127,6 @@ static int squashfs_fill_super(struct su
TRACE("Entered squashfs_fill_superblock\n");
- /*
- * squashfs provides 'backing_dev_info' in order to disable read-ahead. For
- * squashfs, I/O is not deferred, it is done immediately in read_folio,
- * which means the user would always have to wait their own I/O. So the effect
- * of readahead is very weak for squashfs. squashfs_bdi_init will set
- * sb->s_bdi->ra_pages and sb->s_bdi->io_pages to 0 and close readahead for
- * squashfs.
- */
- err = squashfs_bdi_init(sb);
- if (err) {
- errorf(fc, "squashfs init bdi failed");
- return err;
- }
-
sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
if (sb->s_fs_info == NULL) {
ERROR("Failed to allocate squashfs_sb_info\n");
_
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
