linux-kernel - [PATCH 1/8] cachefiles: Fix incorrect block calculations in __cachefiles_prepare

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Message-ID: <20240821024301.1058918-2-wozizhi@huawei.com>
Date: Wed, 21 Aug 2024 10:42:54 +0800
From: Zizhi Wo <wozizhi@...wei.com>
To: <netfs@...ts.linux.dev>, <dhowells@...hat.com>, <jlayton@...nel.org>
CC: <hsiangkao@...ux.alibaba.com>, <jefflexu@...ux.alibaba.com>,
	<zhujia.zj@...edance.com>, <linux-erofs@...ts.ozlabs.org>,
	<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<wozizhi@...wei.com>, <libaokun1@...wei.com>, <yangerkun@...wei.com>,
	<houtao1@...wei.com>, <yukuai3@...wei.com>
Subject: [PATCH 1/8] cachefiles: Fix incorrect block calculations in __cachefiles_prepare_write()

In the __cachefiles_prepare_write function, DIO aligns blocks using
PAGE_SIZE as the unit. And currently cachefiles_add_cache() binds
cache->bsize with the requirement that it must not exceed PAGE_SIZE.
However, if cache->bsize is smaller than PAGE_SIZE, the calculated block
count will be incorrect in __cachefiles_prepare_write().

Set the block size to cache->bsize to resolve this issue.

Fixes: 047487c947e8 ("cachefiles: Implement the I/O routines")
Signed-off-by: Zizhi Wo <wozizhi@...wei.com>
---
 fs/cachefiles/io.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index a91acd03ee12..59c5c08f921a 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -524,10 +524,10 @@ int __cachefiles_prepare_write(struct cachefiles_object *object,
 	struct cachefiles_cache *cache = object->volume->cache;
 	loff_t start = *_start, pos;
 	size_t len = *_len;
-	int ret;
+	int ret, block_size = cache->bsize;
 
 	/* Round to DIO size */
-	start = round_down(*_start, PAGE_SIZE);
+	start = round_down(*_start, block_size);
 	if (start != *_start || *_len > upper_len) {
 		/* Probably asked to cache a streaming write written into the
 		 * pagecache when the cookie was temporarily out of service to
@@ -537,7 +537,7 @@ int __cachefiles_prepare_write(struct cachefiles_object *object,
 		return -ENOBUFS;
 	}
 
-	*_len = round_up(len, PAGE_SIZE);
+	*_len = round_up(len, block_size);
 
 	/* We need to work out whether there's sufficient disk space to perform
 	 * the write - but we can skip that check if we have space already
@@ -563,7 +563,7 @@ int __cachefiles_prepare_write(struct cachefiles_object *object,
 	 * space, we need to see if it's fully allocated.  If it's not, we may
 	 * want to cull it.
 	 */
-	if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
+	if (cachefiles_has_space(cache, 0, *_len / block_size,
 				 cachefiles_has_space_check) == 0)
 		return 0; /* Enough space to simply overwrite the whole block */
 
@@ -595,7 +595,7 @@ int __cachefiles_prepare_write(struct cachefiles_object *object,
 	return ret;
 
 check_space:
-	return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
+	return cachefiles_has_space(cache, 0, *_len / block_size,
 				    cachefiles_has_space_for_write);
 }
 
-- 
2.39.2