linux-kernel - [PATCH v3 11/13] exfat: tweak cluster cache to support zero offset

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Message-ID: <20260114121747.616098-1-chizhiling@163.com>
Date: Wed, 14 Jan 2026 20:17:47 +0800
From: Chi Zhiling <chizhiling@....com>
To: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Namjae Jeon <linkinjeon@...nel.org>,
	Sungjong Seo <sj1557.seo@...sung.com>,
	Yuezhang Mo <yuezhang.mo@...y.com>,
	Chi Zhiling <chizhiling@...inos.cn>,
	Yuezhang Mo <Yuezhang.Mo@...y.com>
Subject: [PATCH v3 11/13] exfat: tweak cluster cache to support zero offset

From: Chi Zhiling <chizhiling@...inos.cn>

The current cache mechanism does not support reading clusters starting
from a file offset of zero. This patch enables that feature in
preparation for subsequent reads of contiguous clusters from offset zero.

1. support finding clusters with zero offset.
2. allow clusters with zero offset to be cached.

Signed-off-by: Chi Zhiling <chizhiling@...inos.cn>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@...y.com>
---
 fs/exfat/cache.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/exfat/cache.c b/fs/exfat/cache.c
index 025b39b7a9ac..73147e153c2c 100644
--- a/fs/exfat/cache.c
+++ b/fs/exfat/cache.c
@@ -92,7 +92,7 @@ static unsigned int exfat_cache_lookup(struct inode *inode,
 	spin_lock(&ei->cache_lru_lock);
 	list_for_each_entry(p, &ei->cache_lru, cache_list) {
 		/* Find the cache of "fclus" or nearest cache. */
-		if (p->fcluster <= fclus && hit->fcluster < p->fcluster) {
+		if (p->fcluster <= fclus && hit->fcluster <= p->fcluster) {
 			hit = p;
 			if (hit->fcluster + hit->nr_contig < fclus) {
 				offset = hit->nr_contig;
@@ -259,7 +259,7 @@ int exfat_get_cluster(struct inode *inode, unsigned int cluster,
 	if (cluster == 0 || *dclus == EXFAT_EOF_CLUSTER)
 		return 0;
 
-	cache_init(&cid, EXFAT_EOF_CLUSTER, EXFAT_EOF_CLUSTER);
+	cache_init(&cid, fclus, *dclus);
 	exfat_cache_lookup(inode, cluster, &cid, &fclus, dclus);
 
 	if (fclus == cluster)
-- 
2.43.0