[RFC PATCH v3 3/5] ntfs3: make crtime user-settable using ptime

[koraynilay]

Since NTFS supports user-settable file creation timestamps, map
provenance time (ptime) to NTFS file creation time (crtime) by using the
newly introduced ptime API (in commit "vfs: add provenance time
(ptime)").

To do this, update ntfs_fileattr_[gs]et(), ntfs_getattr() and make it
persist to disk in ni_write_inode().

The timestamp is now retrievable by using file_getattr() or statx(), and
is settable by using file_setattr() with the FS_XFLAG_PTIME flag.

Assisted-by: Gemini:3.8-flash-high antigravity-cli-1.4.7
Signed-off-by: koraynilay <koray.fra@xxxxxxxxx>
---
 fs/ntfs3/file.c    | 14 ++++++++++++--
 fs/ntfs3/frecord.c |  8 +++++++-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
index 1624f9b014e0..b334449e9beb 100644
--- a/fs/ntfs3/file.c
+++ b/fs/ntfs3/file.c
@@ -124,6 +124,10 @@ int ntfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
 
 	fileattr_fill_flags(fa, flags);
 
+	fa->fsx_ptime.tv_sec = ni->i_crtime.tv_sec;
+	fa->fsx_ptime.tv_nsec = ni->i_crtime.tv_nsec;
+	fa->fsx_xflags |= FS_XFLAG_PTIME;
+
 	return 0;
 }
 
@@ -142,7 +146,7 @@ int ntfs_fileattr_set(const struct mnt_idmap *idmap, struct dentry *dentry,
 	if (unlikely(is_bad_ni(ni)))
 		return -EINVAL;
 
-	if (fileattr_has_fsx(fa))
+	if (fileattr_has_fsx_mask(fa, FS_XFLAG_PTIME))
 		return -EOPNOTSUPP;
 
 	if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL))
@@ -154,6 +158,11 @@ int ntfs_fileattr_set(const struct mnt_idmap *idmap, struct dentry *dentry,
 	if (flags & FS_APPEND_FL)
 		new_fl |= S_APPEND;
 
+	if (fa->fsx_xflags & FS_XFLAG_PTIME) {
+		ni->i_crtime.tv_sec = fa->fsx_ptime.tv_sec;
+		ni->i_crtime.tv_nsec = fa->fsx_ptime.tv_nsec;
+	}
+
 	inode_set_flags(inode, new_fl, S_IMMUTABLE | S_APPEND);
 
 	/* Save nodump flag to return in ntfs_getattr. */
@@ -275,8 +284,9 @@ int ntfs_getattr(const struct mnt_idmap *idmap, const struct path *path,
 	if (unlikely(is_bad_ni(ni)))
 		return -EINVAL;
 
-	stat->result_mask |= STATX_BTIME;
+	stat->result_mask |= (STATX_BTIME | STATX_PTIME);
 	stat->btime = ni->i_crtime;
+	stat->ptime = ni->i_crtime;
 	stat->blksize = ni->mi.sbi->cluster_size; /* 512, 1K, ..., 2M */
 
 	if (inode->i_flags & S_IMMUTABLE)
diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c
index 16ac847de48d..5e4f743a5930 100644
--- a/fs/ntfs3/frecord.c
+++ b/fs/ntfs3/frecord.c
@@ -3215,6 +3215,13 @@ int ni_write_inode(struct inode *inode, int sync, const char *hint)
 		}
 
 		/* Update the access times if they have changed. */
+		ts = ni->i_crtime;
+		dup.cr_time = kernel2nt(&ts);
+		if (std->cr_time != dup.cr_time) {
+			std->cr_time = dup.cr_time;
+			modified = true;
+		}
+
 		ts = inode_get_mtime(inode);
 		dup.m_time = kernel2nt(&ts);
 		if (std->m_time != dup.m_time) {
@@ -3250,7 +3257,6 @@ int ni_write_inode(struct inode *inode, int sync, const char *hint)
 		    (modified || (ni->ni_flags & NI_FLAG_UPDATE_PARENT))
 		    /* Avoid __wait_on_freeing_inode(inode). */
 		    && (sb->s_flags & SB_ACTIVE)) {
-			dup.cr_time = std->cr_time;
 			/* Not critical if this function fail. */
 			re_dirty = ni_update_parent(ni, &dup, sync);
 
-- 
2.56.0