[3/4] fat: add functions to update and truncate the timestamps appropriately

Commit Message

Frank Sorenson Sept. 22, 2018, 8:19 p.m. UTC

Add the fat-specific inode_operation ->update_time() and
fat_truncate_time() function to truncate the inode timestamps
with the appropriate granularity.

Signed-off-by: Frank Sorenson <[e-mail]>
---
 fs/fat/fat.h         |  2 ++
 fs/fat/file.c        |  1 +
 fs/fat/misc.c        | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fat/namei_msdos.c |  1 +
 fs/fat/namei_vfat.c  |  1 +
 5 files changed, 67 insertions(+)

Patch

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index c40f7e69f078..6201c6bdb5f9 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -428,6 +428,8 @@  extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 			      __le16 __time, __le16 __date, u8 time_cs);
 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 			      __le16 *time, __le16 *date, u8 *time_cs);
+extern int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags);
+extern int fat_update_time(struct inode *inode, struct timespec64 *now, int flags);
 extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
 
 int fat_cache_init(void);
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4f3d72fb1e60..19b6b0566411 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -552,4 +552,5 @@  EXPORT_SYMBOL_GPL(fat_setattr);
 const struct inode_operations fat_file_inode_operations = {
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.update_time	= fat_update_time,
 };
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 58580c7e558e..42c4fb063287 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -255,6 +255,68 @@  void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 }
 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 
+/*
+ * truncate the various times with appropriate granularity:
+ *   root inode:
+ *     all times always 0
+ *   all other inodes:
+ *     mtime - 2 seconds
+ *     ctime
+ *       msdos - 2 seconds
+ *       vfat  - 10 milliseconds
+ *     atime - 24 hours (00:00:00 in local timezone)
+ */
+noinline int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+	struct timespec64 ts;
+
+	if (inode->i_ino == MSDOS_ROOT_INO)
+		return 0;
+
+	if (now == NULL) {
+		now = &ts;
+		ts = current_time(inode);
+	}
+
+	if (flags & S_ATIME) {
+		int offset = fat_tz_offset(sbi);
+		long seconds;
+
+		seconds = now->tv_sec;
+		seconds -= (now->tv_sec - offset) % 86400;
+
+		inode->i_atime = (struct timespec64){ seconds, 0 };
+	}
+	if (flags & S_CTIME) {
+		if (sbi->options.isvfat)
+			inode->i_ctime = *now;
+		else
+			inode->i_ctime = (struct timespec64){ now->tv_sec & ~1, 0 };
+	}
+	if (flags & S_MTIME)
+		inode->i_mtime = (struct timespec64){ now->tv_sec & ~1, 0 };
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fat_truncate_time);
+
+int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
+{
+	int iflags = I_DIRTY_TIME;
+
+	if (inode->i_ino == MSDOS_ROOT_INO)
+		return 0;
+	fat_truncate_time(inode, now, flags);
+
+	if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
+	    !(inode->i_sb->s_flags & SB_LAZYTIME))
+		iflags |= I_DIRTY_SYNC;
+
+	__mark_inode_dirty(inode, iflags);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fat_update_time);
+
 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 {
 	int i, err = 0;
diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index efb8c40c9d27..effbdd5fbf6e 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -637,6 +637,7 @@  static const struct inode_operations msdos_dir_inode_operations = {
 	.rename		= msdos_rename,
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.update_time	= fat_update_time,
 };
 
 static void setup(struct super_block *sb)
diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index 82cd1e69cbdf..1daa57cf4bf3 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -1032,6 +1032,7 @@  static const struct inode_operations vfat_dir_inode_operations = {
 	.rename		= vfat_rename,
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.update_time	= fat_update_time,
 };
 
 static void setup(struct super_block *sb)