Merge tag 'y2038-drivers-for-v5.6-signed' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground

Pull y2038 updates from Arnd Bergmann:
 "Core, driver and file system changes

  These are updates to device drivers and file systems that for some
  reason or another were not included in the kernel in the previous
  y2038 series.

  I've gone through all users of time_t again to make sure the kernel is
  in a long-term maintainable state, replacing all remaining references
  to time_t with safe alternatives.

  Some related parts of the series were picked up into the nfsd, xfs,
  alsa and v4l2 trees. A final set of patches in linux-mm removes the
  now unused time_t/timeval/timespec types and helper functions after
  all five branches are merged for linux-5.6, ensuring that no new users
  get merged.

  As a result, linux-5.6, or my backport of the patches to 5.4 [1],
  should be the first release that can serve as a base for a 32-bit
  system designed to run beyond year 2038, with a few remaining caveats:

   - All user space must be compiled with a 64-bit time_t, which will be
     supported in the coming musl-1.2 and glibc-2.32 releases, along
     with installed kernel headers from linux-5.6 or higher.

   - Applications that use the system call interfaces directly need to
     be ported to use the time64 syscalls added in linux-5.1 in place of
     the existing system calls. This impacts most users of futex() and
     seccomp() as well as programming languages that have their own
     runtime environment not based on libc.

   - Applications that use a private copy of kernel uapi header files or
     their contents may need to update to the linux-5.6 version, in
     particular for sound/asound.h, xfs/xfs_fs.h, linux/input.h,
     linux/elfcore.h, linux/sockios.h, linux/timex.h and
     linux/can/bcm.h.

   - A few remaining interfaces cannot be changed to pass a 64-bit
     time_t in a compatible way, so they must be configured to use
     CLOCK_MONOTONIC times or (with a y2106 problem) unsigned 32-bit
     timestamps. Most importantly this impacts all users of 'struct
     input_event'.

   - All y2038 problems that are present on 64-bit machines also apply
     to 32-bit machines. In particular this affects file systems with
     on-disk timestamps using signed 32-bit seconds: ext4 with
     ext3-style small inodes, ext2, xfs (to be fixed soon) and ufs"

[1] https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/log/?h=y2038-endgame

* tag 'y2038-drivers-for-v5.6-signed' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (21 commits)
  Revert "drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC"
  y2038: sh: remove timeval/timespec usage from headers
  y2038: sparc: remove use of struct timex
  y2038: rename itimerval to __kernel_old_itimerval
  y2038: remove obsolete jiffies conversion functions
  nfs: fscache: use timespec64 in inode auxdata
  nfs: fix timstamp debug prints
  nfs: use time64_t internally
  sunrpc: convert to time64_t for expiry
  drm/etnaviv: avoid deprecated timespec
  drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC
  drm/msm: avoid using 'timespec'
  hfs/hfsplus: use 64-bit inode timestamps
  hostfs: pass 64-bit timestamps to/from user space
  packet: clarify timestamp overflow
  tsacct: add 64-bit btime field
  acct: stop using get_seconds()
  um: ubd: use 64-bit time_t where possible
  xtensa: ISS: avoid struct timeval
  dlm: use SO_SNDTIMEO_NEW instead of SO_SNDTIMEO_OLD
  ...

3 files changed, 10 insertions, 9 deletions

diff --git a/arch/um/drivers/cow.h b/arch/um/drivers/cow.h
index 760c507dd5b6..103adac691ed 100644
--- a/arch/um/drivers/cow.h
+++ b/arch/um/drivers/cow.h
@@ -11,7 +11,7 @@ extern int init_cow_file(int fd, char *cow_file, char *backing_file,
 extern int file_reader(__u64 offset, char *buf, int len, void *arg);
 extern int read_cow_header(int (*reader)(__u64, char *, int, void *),
 			   void *arg, __u32 *version_out,
-			   char **backing_file_out, time_t *mtime_out,
+			   char **backing_file_out, long long *mtime_out,
 			   unsigned long long *size_out, int *sectorsize_out,
 			   __u32 *align_out, int *bitmap_offset_out);
 
diff --git a/arch/um/drivers/cow_user.c b/arch/um/drivers/cow_user.c
index 74b0c2686c95..29b46581ddd1 100644
--- a/arch/um/drivers/cow_user.c
+++ b/arch/um/drivers/cow_user.c
@@ -17,6 +17,7 @@
 
 #define PATH_LEN_V1 256
 
+/* unsigned time_t works until year 2106 */
 typedef __u32 time32_t;
 
 struct cow_header_v1 {
@@ -197,7 +198,7 @@ int write_cow_header(char *cow_file, int fd, char *backing_file,
 		     int sectorsize, int alignment, unsigned long long *size)
 {
 	struct cow_header_v3 *header;
-	unsigned long modtime;
+	long long modtime;
 	int err;
 
 	err = cow_seek_file(fd, 0);
@@ -276,7 +277,7 @@ int file_reader(__u64 offset, char *buf, int len, void *arg)
 
 int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg,
 		    __u32 *version_out, char **backing_file_out,
-		    time_t *mtime_out, unsigned long long *size_out,
+		    long long *mtime_out, unsigned long long *size_out,
 		    int *sectorsize_out, __u32 *align_out,
 		    int *bitmap_offset_out)
 {
@@ -363,7 +364,7 @@ int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg,
 
 		/*
 		 * this was used until Dec2005 - 64bits are needed to represent
-		 * 2038+. I.e. we can safely do this truncating cast.
+		 * 2106+. I.e. we can safely do this truncating cast.
 		 *
 		 * Additionally, we must use be32toh() instead of be64toh(), since
 		 * the program used to use the former (tested - I got mtime
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 6627d7c30f37..dcabb463e011 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -561,7 +561,7 @@ static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 	__u32 version;
 	__u32 align;
 	char *backing_file;
-	time_t mtime;
+	time64_t mtime;
 	unsigned long long size;
 	int sector_size;
 	int bitmap_offset;
@@ -600,9 +600,9 @@ static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 	return 0;
 }
 
-static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
+static int backing_file_mismatch(char *file, __u64 size, time64_t mtime)
 {
-	unsigned long modtime;
+	time64_t modtime;
 	unsigned long long actual;
 	int err;
 
@@ -628,7 +628,7 @@ static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
 		return -EINVAL;
 	}
 	if (modtime != mtime) {
-		printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
+		printk(KERN_ERR "mtime mismatch (%lld vs %lld) of COW header vs "
 		       "backing file\n", mtime, modtime);
 		return -EINVAL;
 	}
@@ -671,7 +671,7 @@ static int open_ubd_file(char *file, struct openflags *openflags, int shared,
 		  unsigned long *bitmap_len_out, int *data_offset_out,
 		  int *create_cow_out)
 {
-	time_t mtime;
+	time64_t mtime;
 	unsigned long long size;
 	__u32 version, align;
 	char *backing_file;