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 Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Jeff Layton jlayton@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;