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From:   Vivek Goyal <vgoyal@redhat.com>
To:     linux-fsdevel@vger.kernel.org, virtio-fs@redhat.com,
        miklos@szeredi.hu
Cc:     vgoyal@redhat.com, dgilbert@redhat.com,
        linux-kernel@vger.kernel.org, dan.carpenter@oracle.com
Subject: [PATCH 1/2] virtiofs, dax: Fix smatch warning about loss of info during shift
Date:   Thu,  6 May 2021 14:43:03 -0400
Message-Id: <20210506184304.321645-2-vgoyal@redhat.com>
In-Reply-To: <20210506184304.321645-1-vgoyal@redhat.com>
References: <20210506184304.321645-1-vgoyal@redhat.com>
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Dan reported a smatch warning during potentential loss of info during
left shift if this code is compiled on 32bit systems.

New smatch warnings:
fs/fuse/dax.c:113 fuse_setup_one_mapping() warn: should 'start_idx << 21' be a
+64 bit type?

I ran smatch and found two more instances of similar warning. This patch
fixes all such instances.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 fs/fuse/dax.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index ff99ab2a3c43..f06fdad3f7b1 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -186,7 +186,7 @@ static int fuse_setup_one_mapping(struct inode *inode, unsigned long start_idx,
 	struct fuse_conn_dax *fcd = fm->fc->dax;
 	struct fuse_inode *fi = get_fuse_inode(inode);
 	struct fuse_setupmapping_in inarg;
-	loff_t offset = start_idx << FUSE_DAX_SHIFT;
+	loff_t offset = (loff_t)start_idx << FUSE_DAX_SHIFT;
 	FUSE_ARGS(args);
 	ssize_t err;
 
@@ -872,7 +872,7 @@ static int dmap_writeback_invalidate(struct inode *inode,
 				     struct fuse_dax_mapping *dmap)
 {
 	int ret;
-	loff_t start_pos = dmap->itn.start << FUSE_DAX_SHIFT;
+	loff_t start_pos = (loff_t)dmap->itn.start << FUSE_DAX_SHIFT;
 	loff_t end_pos = (start_pos + FUSE_DAX_SZ - 1);
 
 	ret = filemap_fdatawrite_range(inode->i_mapping, start_pos, end_pos);
@@ -966,7 +966,7 @@ inode_inline_reclaim_one_dmap(struct fuse_conn_dax *fcd, struct inode *inode,
 	dmap = inode_lookup_first_dmap(inode);
 	if (dmap) {
 		start_idx = dmap->itn.start;
-		dmap_start = start_idx << FUSE_DAX_SHIFT;
+		dmap_start = (u64)start_idx << FUSE_DAX_SHIFT;
 		dmap_end = dmap_start + FUSE_DAX_SZ - 1;
 	}
 	up_read(&fi->dax->sem);
@@ -1118,7 +1118,7 @@ static int lookup_and_reclaim_dmap(struct fuse_conn_dax *fcd,
 {
 	int ret;
 	struct fuse_inode *fi = get_fuse_inode(inode);
-	loff_t dmap_start = start_idx << FUSE_DAX_SHIFT;
+	loff_t dmap_start = (loff_t)start_idx << FUSE_DAX_SHIFT;
 	loff_t dmap_end = (dmap_start + FUSE_DAX_SZ) - 1;
 
 	down_write(&fi->i_mmap_sem);
-- 
2.25.4