xfs: fallocate() should call file_modified()

stable inclusion
from stable-v5.10.167
commit 308dfe49eb753d7263fa4e001251d733c710ed14
category: bugfix
bugzilla: 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=308dfe49eb753d7263fa4e001251d733c710ed14



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commit fbe7e520 upstream.

In XFS, we always update the inode change and modification time when
any fallocate() operation succeeds.  Furthermore, as various
fallocate modes can change the file contents (extending EOF,
punching holes, zeroing things, shifting extents), we should drop
file privileges like suid just like we do for a regular write().
There's already a VFS helper that figures all this out for us, so
use that.

The net effect of this is that we no longer drop suid/sgid if the
caller is root, but we also now drop file capabilities.

We also move the xfs_update_prealloc_flags() function so that it now
is only called by the scope that needs to set the the prealloc flag.

Based on a patch from Darrick Wong.

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>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: Long Li <leo.lilong@huawei.com>