[PATCH v2 3/3] fat: report creation time in statx

[Chung-Chiang Cheng <cccheng@synology.com>]

creation time is no longer mixed with change time. Add a in-memory
field for it, and report it in statx.

Signed-off-by: Chung-Chiang Cheng <cccheng@synology.com>
---
 fs/fat/fat.h   |  1 +
 fs/fat/file.c  |  6 ++++++
 fs/fat/inode.c | 12 ++++++++++--
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 508b4f2a1ffb..e4409ee82ea9 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -126,6 +126,7 @@ struct msdos_inode_info {
 	struct hlist_node i_fat_hash;	/* hash by i_location */
 	struct hlist_node i_dir_hash;	/* hash by i_logstart */
 	struct rw_semaphore truncate_lock; /* protect bmap against truncate */
+	struct timespec64 i_crtime;	/* File creation (birth) time */
 	struct inode vfs_inode;
 };
 
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 178c1dde3488..b56f64cc1c9c 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -406,6 +406,12 @@ int fat_getattr(struct user_namespace *mnt_userns, const struct path *path,
 		/* Use i_pos for ino. This is used as fileid of nfs. */
 		stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
 	}
+
+	if (request_mask & STATX_BTIME) {
+		stat->result_mask |= STATX_BTIME;
+		stat->btime = MSDOS_I(inode)->i_crtime;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(fat_getattr);
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index f2ac55cd4ea4..23fac3181fa7 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -568,10 +568,14 @@ int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 
 	fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
 	inode->i_ctime = inode->i_mtime;
-	if (sbi->options.isvfat)
+	if (sbi->options.isvfat) {
 		fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
-	else
+		fat_time_fat2unix(sbi, &MSDOS_I(inode)->i_crtime, de->ctime,
+				  de->cdate, de->ctime_cs);
+	} else {
 		fat_truncate_atime(sbi, &inode->i_mtime, &inode->i_atime);
+		fat_truncate_crtime(sbi, &inode->i_mtime, &MSDOS_I(inode)->i_crtime);
+	}
 
 	return 0;
 }
@@ -756,6 +760,8 @@ static struct inode *fat_alloc_inode(struct super_block *sb)
 	ei->i_logstart = 0;
 	ei->i_attrs = 0;
 	ei->i_pos = 0;
+	ei->i_crtime.tv_sec = 0;
+	ei->i_crtime.tv_nsec = 0;
 
 	return &ei->vfs_inode;
 }
@@ -887,6 +893,8 @@ static int __fat_write_inode(struct inode *inode, int wait)
 			  &raw_entry->date, NULL);
 	if (sbi->options.isvfat) {
 		__le16 atime;
+		fat_time_unix2fat(sbi, &MSDOS_I(inode)->i_crtime, &raw_entry->ctime,
+				  &raw_entry->cdate, &raw_entry->ctime_cs);
 		fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 				  &raw_entry->adate, NULL);
 	}
-- 
2.34.1