From: Long Li <longli@microsoft.com>
Date: Sun, 16 Dec 2018 23:17:04 +0000
Subject: [PATCH] CIFS: use the correct length when pinning memory for direct
I/O for write
Git-commit: b6bc8a7b993e62f82415a5e3e4a6469e80fea19c
Patch-mainline: v5.0-rc1
References: bsc#1144333
The current code attempts to pin memory using the largest possible wsize
based on the currect SMB credits. This doesn't cause kernel oops but this
is not optimal as we may pin more pages then actually needed.
Fix this by only pinning what are needed for doing this write I/O.
Signed-off-by: Long Li <longli@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Joey Pabalinas <joeypabalinas@gmail.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
fs/cifs/file.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index c9bc56b1baac..179991435777 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2617,11 +2617,13 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
if (rc)
break;
+ cur_len = min_t(const size_t, len, wsize);
+
if (ctx->direct_io) {
ssize_t result;
result = iov_iter_get_pages_alloc(
- from, &pagevec, wsize, &start);
+ from, &pagevec, cur_len, &start);
if (result < 0) {
cifs_dbg(VFS,
"direct_writev couldn't get user pages "
--
2.16.4