linux-ext4 - [PATCH 3/3] ext4: Use bdev_getblk() to avoid memory reclaim in readahead path

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Date:   Fri, 11 Aug 2023 17:15:28 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     akpm@...ux-foundation.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Hui Zhu <teawater@...group.com>, linux-fsdevel@...r.kernel.org,
        linux-ext4@...r.kernel.org
Subject: [PATCH 3/3] ext4: Use bdev_getblk() to avoid memory reclaim in readahead path

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.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reported-by: Hui Zhu <teawater@...group.com>
Link: https://lore.kernel.org/linux-fsdevel/20230811035705.3296-1-teawaterz@linux.alibaba.com/
---
 fs/ext4/super.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c94ebf704616..48524314be97 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -254,7 +254,8 @@ struct buffer_head *ext4_sb_bread_unmovable(struct super_block *sb,
 
 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))
-- 
2.40.1