linux-kernel - [PATCH v3 3/5] Xarray: distinguish large entries correctly in xas_split

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Message-Id: <20241213122523.12764-4-shikemeng@huaweicloud.com>
Date: Fri, 13 Dec 2024 20:25:21 +0800
From: Kemeng Shi <shikemeng@...weicloud.com>
To: akpm@...ux-foundation.org,
	willy@...radead.org
Cc: linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH v3 3/5] Xarray: distinguish large entries correctly in xas_split_alloc()

We don't support large entries which expand two more level xa_node in
split. For case "xas->xa_shift + 2 * XA_CHUNK_SHIFT == order", we also
need two level of xa_node to expand. Distinguish entry as large entry in
case "xas->xa_shift + 2 * XA_CHUNK_SHIFT == order".

As max order of folio in pagecache (MAX_PAGECACHE_ORDER) is <=
(XA_CHUNK_SHIFT * 2 - 1), this change is more likely a cleanup...

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 lib/xarray.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/xarray.c b/lib/xarray.c
index d0732c5b8403..3fac3f2cea9d 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1022,7 +1022,7 @@ void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
 	unsigned int mask = xas->xa_sibs;
 
 	/* XXX: no support for splitting really large entries yet */
-	if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
+	if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT <= order))
 		goto nomem;
 	if (xas->xa_shift + XA_CHUNK_SHIFT > order)
 		return;
-- 
2.30.0