linux-ext4 - [PATCH v2 4/8] buffer: Use bdev_getblk() to avoid memory reclaim in readahead path

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Message-Id: <20230914150011.843330-5-willy@infradead.org>
Date:   Thu, 14 Sep 2023 16:00:07 +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 v2 4/8] buffer: Use bdev_getblk() to avoid memory reclaim in readahead path

__getblk() 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>
---
 fs/buffer.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 3fe293c9f3ca..58546bfd8903 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1464,7 +1464,9 @@ EXPORT_SYMBOL(__getblk_gfp);
  */
 void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
 {
-	struct buffer_head *bh = __getblk(bdev, block, size);
+	struct buffer_head *bh = bdev_getblk(bdev, block, size,
+			GFP_NOWAIT | __GFP_MOVABLE);
+
 	if (likely(bh)) {
 		bh_readahead(bh, REQ_RAHEAD);
 		brelse(bh);
-- 
2.40.1