[PATCH 5.9 347/391] ext4: fix bs < ps issue reported with dioread_nolock mount opt

[Greg Kroah-Hartman]

From: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>

commit d1e18b8824dd50cff255e6cecf515ea598eaf9f0 upstream.

left shifting m_lblk by blkbits was causing value overflow and hence
it was not able to convert unwritten to written extent.
So, make sure we typecast it to loff_t before do left shift operation.
Also in func ext4_convert_unwritten_io_end_vec(), make sure to initialize
ret variable to avoid accidentally returning an uninitialized ret.

This patch fixes the issue reported in ext4 for bs < ps with
dioread_nolock mount option.

Fixes: c8cc88163f40df39e50c ("ext4: Add support for blocksize < pagesize in dioread_nolock")
Cc: stable@xxxxxxxxxx
Reported-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/af902b5db99e8b73980c795d84ad7bb417487e76.1602168865.git.riteshh@xxxxxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/ext4/extents.c |    2 +-
 fs/ext4/inode.c   |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4770,7 +4770,7 @@ int ext4_convert_unwritten_extents(handl
 
 int ext4_convert_unwritten_io_end_vec(handle_t *handle, ext4_io_end_t *io_end)
 {
-	int ret, err = 0;
+	int ret = 0, err = 0;
 	struct ext4_io_end_vec *io_end_vec;
 
 	/*
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2257,7 +2257,7 @@ static int mpage_process_page(struct mpa
 					err = PTR_ERR(io_end_vec);
 					goto out;
 				}
-				io_end_vec->offset = mpd->map.m_lblk << blkbits;
+				io_end_vec->offset = (loff_t)mpd->map.m_lblk << blkbits;
 			}
 			*map_bh = true;
 			goto out;