Merge branch 'limits' of https://github.com/deepa-hub/vfs into y2038

The series is an update and a more complete version of the
previously posted series at
https://lore.kernel.org/linux-fsdevel/20180122020426.2988-1-deepa.kernel@gmail.com/

Thanks to Arnd Bergmann for doing a few preliminary reviews.
They helped me fix a few issues I had overlooked.

The limits (sometimes granularity also) for the filesystems updated here are according to the
following table:

File system   Time type                      Start year Expiration year Granularity
cramfs        fixed                          0          0
romfs         fixed                          0          0
pstore        ascii seconds (27 digit ascii) S64_MIN    S64_MAX         1
coda          INT64                          S64_MIN    S64_MAX         1
omfs          64-bit milliseconds            0          U64_MAX/ 1000   NSEC_PER_MSEC
befs          unsigned 48-bit seconds        0          0xffffffffffff  alloc_super
bfs           unsigned 32-bit seconds        0          U32_MAX         alloc_super
efs           unsigned 32-bit seconds        0          U32_MAX         alloc_super
ext2          signed 32-bit seconds          S32_MIN    S32_MAX         alloc_super
ext3          signed 32-bit seconds          S32_MIN    S32_MAX         alloc_super
ext4 (old)    signed 32-bit seconds          S32_MIN    S32_MAX         alloc_super
ext4 (extra)  34-bit seconds, 30-bit ns      S32_MIN    0x37fffffff     1
freevxfs      u32 secs/usecs                 0          U32_MAX         alloc_super
jffs2         unsigned 32-bit seconds        0          U32_MAX         alloc_super
jfs           unsigned 32-bit seconds/ns     0          U32_MAX         1
minix         unsigned 32-bit seconds        0          U32_MAX         alloc_super
qnx4          unsigned 32-bit seconds        0          U32_MAX         alloc_super
qnx6          unsigned 32-bit seconds        0          U32_MAX         alloc_super
reiserfs      unsigned 32-bit seconds        0          U32_MAX         alloc_super
squashfs      unsigned 32-bit seconds        0          U32_MAX         alloc_super
ufs1          signed 32-bit seconds          S32_MIN    S32_MAX         NSEC_PER_SEC
ufs2          signed 64-bit seconds/u32 ns   S64_MIN    S64_MAX         1
xfs           signed 32-bit seconds/ns       S32_MIN    S32_MAX         1
ceph          unsigned 32-bit second/ns      0          U32_MAX         1000
sysv          unsigned 32-bit seconds        0          U32_MAX         alloc_super
affs          u32 day, min, ticks            1978       u32_max days    NSEC_PER_SEC
nfsv2         unsigned 32-bit seconds/ns     0          U32_MAX         1
nfsv3         unsigned 32-bit seconds/ns     0          U32_MAX         1000
nfsv4         u64 seconds/u32 ns             S64_MIN    S64_MAX         1000
isofs         u8 year since 1900 (fixable)   1900       2155            alloc_super
hpfs          unsigned 32-bit seconds        1970       2106            alloc_super
fat           7-bit years, 2s resolution     1980       2107
cifs (smb)    7-bit years                    1980       2107
cifs (modern) 64-bit 100ns since 1601        1601       30828
9p (9P2000)   unsigned 32-bit seconds        1970       2106
9p (9P2000.L) signed 64-bit seconds, ns      1970       S64_MAX

Granularity column filled in by the alloc_super() in the above table indicates that
the granularity is NSEC_PER_SEC.
Note that anything not mentioned above still has the default limits
S64_MIN..S64_MAX.

The patches in the series are as structured below:
1. Add vfs support to maintain the limits per filesystem.
2. Add a new timestamp_truncate() api for clamping timestamps
   according to the filesystem limits.
3. Add a warning for mount syscall to indicate the impending
   expiry of timestamps.
4. Modify utimes to clamp the timestamps.
5. Fill in limits for filesystems.

A test for checking file system timestamp limits has been posted
at https://www.spinics.net/lists/fstests/msg12262.html

Changes since v8:
* Dropped orangefs patch because of ongoing discussion
* Dropped adfs patch because a conflict with Russell's ADFS series
Changes since v7:
* Dropped fat modifications from timespec_truncate patch
* Leverage timestamp_truncate function in utimes
* Added a fix for pstore ramoops timestamps
* Added ext4 warning for inodes without room for extended timestamps.
* Made mount warning more human readable
Changes since v6:
* No change in mount behavior because of expiry of timestamps.
* Included limits for more filesystems.
Changes since v5:
* Dropped y2038-specific changes
Changes since v4:
* Added documentation for boot param
Changes since v3:
* Remove redundant initializations in libfs.c
* Change early_param to __setup similar to other root mount options.
* Fix documentation warning
Changes since v2:
* Introduce early boot param override for checks.
* Drop afs patch for timestamp limits.
Changes since v1:
* return EROFS on mount errors
* fix mtime copy/paste error in utimes

* 'limits' of https://github.com/deepa-hub/vfs:
  isofs: Initialize filesystem timestamp ranges
  pstore: fs superblock limits
  fs: omfs: Initialize filesystem timestamp ranges
  fs: hpfs: Initialize filesystem timestamp ranges
  fs: ceph: Initialize filesystem timestamp ranges
  fs: sysv: Initialize filesystem timestamp ranges
  fs: affs: Initialize filesystem timestamp ranges
  fs: fat: Initialize filesystem timestamp ranges
  fs: cifs: Initialize filesystem timestamp ranges
  fs: nfs: Initialize filesystem timestamp ranges
  ext4: Initialize timestamps limits
  9p: Fill min and max timestamps in sb
  fs: Fill in max and min timestamps in superblock
  utimes: Clamp the timestamps before update
  mount: Add mount warning for impending timestamp expiry
  timestamp_truncate: Replace users of timespec64_trunc
  vfs: Add timestamp_truncate() api
  vfs: Add file timestamp range support

Link: https://lore.kernel.org/lkml/20190730014924.2193-1-deepa.kernel@gmail.com/
Link: https://lore.kernel.org/lkml/20190830154744.4868-1-deepa.kernel@gmail.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

2 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 997a530ff4e9..7e6be3bf0ce0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -726,6 +726,8 @@ struct inode {
 	void			*i_private; /* fs or device private pointer */
 } __randomize_layout;
 
+struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode);
+
 static inline unsigned int i_blocksize(const struct inode *node)
 {
 	return (1 << node->i_blkbits);
@@ -1448,6 +1450,9 @@ struct super_block {
 
 	/* Granularity of c/m/atime in ns (cannot be worse than a second) */
 	u32			s_time_gran;
+	/* Time limits for c/m/atime in seconds */
+	time64_t		   s_time_min;
+	time64_t		   s_time_max;
 #ifdef CONFIG_FSNOTIFY
 	__u32			s_fsnotify_mask;
 	struct fsnotify_mark_connector __rcu	*s_fsnotify_marks;
diff --git a/include/linux/time64.h b/include/linux/time64.h
index a620ee610b9f..19125489ae94 100644
--- a/include/linux/time64.h
+++ b/include/linux/time64.h
@@ -30,6 +30,8 @@ struct itimerspec64 {
 
 /* Located here for timespec[64]_valid_strict */
 #define TIME64_MAX			((s64)~((u64)1 << 63))
+#define TIME64_MIN			(-TIME64_MAX - 1)
+
 #define KTIME_MAX			((s64)~((u64)1 << 63))
 #define KTIME_SEC_MAX			(KTIME_MAX / NSEC_PER_SEC)