Re: [PATCH 6/6] xfs: port xfs_ioc_start_commit to multigrain timestamps

Jeff Layton
2024-12-04T04:01:17Z

On Tue, 2024-12-03 at 19:03 -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
>
> Take advantage of the multigrain timestamp APIs to ensure that nobody
> can sneak in and write things to a file between starting a file update
> operation and committing the results. This should have been part of the
> multigrain timestamp merge, but I forgot to fling it at jlayton when he
> resubmitted the patchset due to developer bandwidth problems.
>
> Cc: jlayton@kernel.org
> Cc: <stable@vger.kernel.org> # v6.13-rc1
> Fixes: 4e40eff0b5737c ("fs: add infrastructure for multigrain timestamps")
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
> fs/xfs/xfs_exchrange.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c
> index 9ab05ad224d127..dd24de420714ab 100644
> --- a/fs/xfs/xfs_exchrange.c
> +++ b/fs/xfs/xfs_exchrange.c
> @@ -854,7 +854,7 @@ xfs_ioc_start_commit(
> struct xfs_commit_range __user *argp)
> {
> struct xfs_commit_range args = { };
> - struct timespec64 ts;
> + struct kstat kstat;
> struct xfs_commit_range_fresh *kern_f;
> struct xfs_commit_range_fresh __user *user_f;
> struct inode *inode2 = file_inode(file);
> @@ -871,12 +871,12 @@ xfs_ioc_start_commit(
> memcpy(&kern_f->fsid, ip2->i_mount->m_fixedfsid, sizeof(xfs_fsid_t));
>
> xfs_ilock(ip2, lockflags);
> - ts = inode_get_ctime(inode2);
> - kern_f->file2_ctime = ts.tv_sec;
> - kern_f->file2_ctime_nsec = ts.tv_nsec;
> - ts = inode_get_mtime(inode2);
> - kern_f->file2_mtime = ts.tv_sec;
> - kern_f->file2_mtime_nsec = ts.tv_nsec;
> + /* Force writing of a distinct ctime if any writes happen. */
> + fill_mg_cmtime(&kstat, STATX_CTIME | STATX_MTIME, inode2);
> + kern_f->file2_ctime = kstat.ctime.tv_sec;
> + kern_f->file2_ctime_nsec = kstat.ctime.tv_nsec;
> + kern_f->file2_mtime = kstat.mtime.tv_sec;
> + kern_f->file2_mtime_nsec = kstat.mtime.tv_nsec;
> kern_f->file2_ino = ip2->i_ino;
> kern_f->file2_gen = inode2->i_generation;
> kern_f->magic = XCR_FRESH_MAGIC;
>

Looks good!

Reviewed-by: Jeff Layton <jlayton@kernel.org>