[patch 008/111] fs/hpfs: extend gmt_to_local() conversion to 64-bit times

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From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: fs/hpfs: extend gmt_to_local() conversion to 64-bit times

The VFS timestamps are all 64-bit now, the only missing piece for hpfs is
the internal conversion function.  One interesting bit about hpfs is that
it can already deal with moving the 136 year window of its timestamps to
support a much wider range than other file systems with 32-bit timestamps.
It also treats the timestamps as 'unsigned' on 64-bit architectures (but
signed on 32-bit, because time_t always around to negative numbers in
2038).

Changing the conversion to use time64_t makes 32-bit architectures behave
the same way as 64-bit.  For completeness, this also adds a clamp_t call
for each conversion, so we don't wrap the timestamps but instead stay
within the [0..U32_MAX] range of the on-disk timestamps.

Link: http://lkml.kernel.org/r/20180718115017.742609-3-arnd@xxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Mikulas Patocka <mikulas@xxxxxxxxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 fs/hpfs/hpfs_fn.h |   13 ++++++++++---
 fs/hpfs/namei.c   |   12 ++++++------
 2 files changed, 16 insertions(+), 9 deletions(-)

--- a/fs/hpfs/hpfs_fn.h~hpfs-extend-gmt_to_local-conversion-to-64-bit-times
+++ a/fs/hpfs/hpfs_fn.h
@@ -334,16 +334,23 @@ long hpfs_ioctl(struct file *file, unsig
  * local time (HPFS) to GMT (Unix)
  */
 
-static inline time_t local_to_gmt(struct super_block *s, time32_t t)
+static inline time64_t local_to_gmt(struct super_block *s, time32_t t)
 {
 	extern struct timezone sys_tz;
 	return t + sys_tz.tz_minuteswest * 60 + hpfs_sb(s)->sb_timeshift;
 }
 
-static inline time32_t gmt_to_local(struct super_block *s, time_t t)
+static inline time32_t gmt_to_local(struct super_block *s, time64_t t)
 {
 	extern struct timezone sys_tz;
-	return t - sys_tz.tz_minuteswest * 60 - hpfs_sb(s)->sb_timeshift;
+	t = t - sys_tz.tz_minuteswest * 60 - hpfs_sb(s)->sb_timeshift;
+
+	return clamp_t(time64_t, t, 0, U32_MAX);
+}
+
+static inline time32_t local_get_seconds(struct super_block *s)
+{
+	return gmt_to_local(s, ktime_get_real_seconds());
 }
 
 /*
--- a/fs/hpfs/namei.c~hpfs-extend-gmt_to_local-conversion-to-64-bit-times
+++ a/fs/hpfs/namei.c
@@ -11,7 +11,7 @@
 
 static void hpfs_update_directory_times(struct inode *dir)
 {
-	time_t t = get_seconds();
+	time64_t t = local_to_gmt(dir->i_sb, local_get_seconds(dir->i_sb));
 	if (t == dir->i_mtime.tv_sec &&
 	    t == dir->i_ctime.tv_sec)
 		return;
@@ -50,7 +50,7 @@ static int hpfs_mkdir(struct inode *dir,
 	/*dee.archive = 0;*/
 	dee.hidden = name[0] == '.';
 	dee.fnode = cpu_to_le32(fno);
-	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(gmt_to_local(dir->i_sb, get_seconds()));
+	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(local_get_seconds(dir->i_sb));
 	result = new_inode(dir->i_sb);
 	if (!result)
 		goto bail2;
@@ -91,7 +91,7 @@ static int hpfs_mkdir(struct inode *dir,
 	dnode->root_dnode = 1;
 	dnode->up = cpu_to_le32(fno);
 	de = hpfs_add_de(dir->i_sb, dnode, "\001\001", 2, 0);
-	de->creation_date = de->write_date = de->read_date = cpu_to_le32(gmt_to_local(dir->i_sb, get_seconds()));
+	de->creation_date = de->write_date = de->read_date = cpu_to_le32(local_get_seconds(dir->i_sb));
 	if (!(mode & 0222)) de->read_only = 1;
 	de->first = de->directory = 1;
 	/*de->hidden = de->system = 0;*/
@@ -151,7 +151,7 @@ static int hpfs_create(struct inode *dir
 	dee.archive = 1;
 	dee.hidden = name[0] == '.';
 	dee.fnode = cpu_to_le32(fno);
-	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(gmt_to_local(dir->i_sb, get_seconds()));
+	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(local_get_seconds(dir->i_sb));
 
 	result = new_inode(dir->i_sb);
 	if (!result)
@@ -238,7 +238,7 @@ static int hpfs_mknod(struct inode *dir,
 	dee.archive = 1;
 	dee.hidden = name[0] == '.';
 	dee.fnode = cpu_to_le32(fno);
-	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(gmt_to_local(dir->i_sb, get_seconds()));
+	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(local_get_seconds(dir->i_sb));
 
 	result = new_inode(dir->i_sb);
 	if (!result)
@@ -314,7 +314,7 @@ static int hpfs_symlink(struct inode *di
 	dee.archive = 1;
 	dee.hidden = name[0] == '.';
 	dee.fnode = cpu_to_le32(fno);
-	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(gmt_to_local(dir->i_sb, get_seconds()));
+	dee.creation_date = dee.write_date = dee.read_date = cpu_to_le32(local_get_seconds(dir->i_sb));
 
 	result = new_inode(dir->i_sb);
 	if (!result)
_



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