netdev - [PATCH 26/39] convert cachestat(2)

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Message-Id: <20240730051625.14349-26-viro@kernel.org>
Date: Tue, 30 Jul 2024 01:16:12 -0400
From: viro@...nel.org
To: linux-fsdevel@...r.kernel.org
Cc: amir73il@...il.com,
	bpf@...r.kernel.org,
	brauner@...nel.org,
	cgroups@...r.kernel.org,
	kvm@...r.kernel.org,
	netdev@...r.kernel.org,
	torvalds@...ux-foundation.org
Subject: [PATCH 26/39] convert cachestat(2)

From: Al Viro <viro@...iv.linux.org.uk>

fdput() can be transposed with copy_to_user()

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 mm/filemap.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 0b5cbd644fdd..9ef41935b0a7 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -4387,31 +4387,25 @@ SYSCALL_DEFINE4(cachestat, unsigned int, fd,
 		struct cachestat_range __user *, cstat_range,
 		struct cachestat __user *, cstat, unsigned int, flags)
 {
-	struct fd f = fdget(fd);
+	CLASS(fd, f)(fd);
 	struct address_space *mapping;
 	struct cachestat_range csr;
 	struct cachestat cs;
 	pgoff_t first_index, last_index;
 
-	if (!fd_file(f))
+	if (fd_empty(f))
 		return -EBADF;
 
 	if (copy_from_user(&csr, cstat_range,
-			sizeof(struct cachestat_range))) {
-		fdput(f);
+			sizeof(struct cachestat_range)))
 		return -EFAULT;
-	}
 
 	/* hugetlbfs is not supported */
-	if (is_file_hugepages(fd_file(f))) {
-		fdput(f);
+	if (is_file_hugepages(fd_file(f)))
 		return -EOPNOTSUPP;
-	}
 
-	if (flags != 0) {
-		fdput(f);
+	if (flags != 0)
 		return -EINVAL;
-	}
 
 	first_index = csr.off >> PAGE_SHIFT;
 	last_index =
@@ -4419,7 +4413,6 @@ SYSCALL_DEFINE4(cachestat, unsigned int, fd,
 	memset(&cs, 0, sizeof(struct cachestat));
 	mapping = fd_file(f)->f_mapping;
 	filemap_cachestat(mapping, first_index, last_index, &cs);
-	fdput(f);
 
 	if (copy_to_user(cstat, &cs, sizeof(struct cachestat)))
 		return -EFAULT;
-- 
2.39.2