+ ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch added to mm-unstable branch

+ ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: ext4: use bdev_getblk() to avoid memory reclaim in readahead path
has been added to the -mm mm-unstable branch.  Its filename is
     ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: ext4: use bdev_getblk() to avoid memory reclaim in readahead path
Date: Thu, 14 Sep 2023 16:00:06 +0100

sb_getblk_gfp adds __GFP_NOFAIL, which is unnecessary for readahead; we're
quite comfortable with the possibility that we may not get a bh back. 
Switch to bdev_getblk() which does not include __GFP_NOFAIL.

Link: https://lkml.kernel.org/r/20230914150011.843330-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: Hui Zhu <teawater@antgroup.com>
Closes: https://lore.kernel.org/linux-fsdevel/20230811035705.3296-1-teawaterz@linux.alibaba.com/
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/ext4/super.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/ext4/super.c~ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path
+++ a/fs/ext4/super.c
@@ -255,7 +255,8 @@ struct buffer_head *ext4_sb_bread_unmova
 
 void ext4_sb_breadahead_unmovable(struct super_block *sb, sector_t block)
 {
-	struct buffer_head *bh = sb_getblk_gfp(sb, block, 0);
+	struct buffer_head *bh = bdev_getblk(sb->s_bdev, block,
+			sb->s_blocksize, GFP_NOWAIT);
 
 	if (likely(bh)) {
 		if (trylock_buffer(bh))
_

Patches currently in -mm which might be from willy@infradead.org are

mm-convert-dax-lock-unlock-page-to-lock-unlock-folio.patch
buffer-pass-gfp-flags-to-folio_alloc_buffers.patch
buffer-hoist-gfp-flags-from-grow_dev_page-to-__getblk_gfp.patch
ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch
buffer-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch
buffer-convert-getblk_unmovable-and-__getblk-to-use-bdev_getblk.patch
buffer-convert-sb_getblk-to-call-__getblk.patch
ext4-call-bdev_getblk-from-sb_getblk_gfp.patch
buffer-remove-__getblk_gfp.patch