vfs: fix readahead(2) on block devices

stable inclusion
from stable-v4.19.299
commit 70409dcd485a244b9f508aa6cdb21ac899a85dc1
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8MCB5
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=70409dcd485a244b9f508aa6cdb21ac899a85dc1



--------------------------------

[ Upstream commit 7116c0af4b8414b2f19fdb366eea213cbd9d91c2 ]

Readahead was factored to call generic_fadvise.  That refactor added an
S_ISREG restriction which broke readahead on block devices.

In addition to S_ISREG, this change checks S_ISBLK to fix block device
readahead.  There is no change in behavior with any file type besides block
devices in this change.

Fixes: 3d8f7615 ("vfs: implement readahead(2) using POSIX_FADV_WILLNEED")
Signed-off-by: Reuben Hawkins <reubenhwk@gmail.com>
Link: https://lore.kernel.org/r/20231003015704.2415-1-reubenhwk@gmail.com


Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>