xfs: port xfs_ioc_start_commit to multigrain timestamps

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: <stable@vger.kernel.org> # v6.13-rc1
Fixes: 4e40eff0b5 ("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>
This commit is contained in:
Darrick J. Wong 2024-12-02 10:58:11 -08:00
parent 7f8b718c58
commit 12f2930f5f

View File

@ -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;