xfs: set prealloc flag in xfs_alloc_file_space()

stable inclusion
from stable-v5.10.167
commit 8cf9400f8948781cc9175f94666421e77622d639
category: bugfix
bugzilla: 188220, https://gitee.com/openeuler/kernel/issues/I76JSK
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=8cf9400f8948781cc9175f94666421e77622d639



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

commit 0b02c8c0 upstream.

[backport for 5.10.y]

Now that we only call xfs_update_prealloc_flags() from
xfs_file_fallocate() in the case where we need to set the
preallocation flag, do this in xfs_alloc_file_space() where we
already have the inode joined into a transaction and get
rid of the call to xfs_update_prealloc_flags() from the fallocate
code.

This also means that we now correctly avoid setting the
XFS_DIFLAG_PREALLOC flag when xfs_is_always_cow_inode() is true, as
these inodes will never have preallocated extents.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	fs/xfs/xfs_bmap_util.c

Signed-off-by: Long Li <leo.lilong@huawei.com>