ext4 has different overflow limits for max filesystem
timestamps based on the extra bytes available.
The timestamp limits are calculated according to the
encoding table in
a4dad1ae24f85i(ext4: Fix handling of extended tv_sec):
* extra msb of adjust for signed
* epoch 32-bit 32-bit tv_sec to
* bits time decoded 64-bit tv_sec 64-bit tv_sec valid time range
* 0 0 1 -0x80000000..-0x00000001 0x000000000 1901-12-13..1969-12-31
* 0 0 0 0x000000000..0x07fffffff 0x000000000 1970-01-01..2038-01-19
* 0 1 1 0x080000000..0x0ffffffff 0x100000000 2038-01-19..2106-02-07
* 0 1 0 0x100000000..0x17fffffff 0x100000000 2106-02-07..2174-02-25
* 1 0 1 0x180000000..0x1ffffffff 0x200000000 2174-02-25..2242-03-16
* 1 0 0 0x200000000..0x27fffffff 0x200000000 2242-03-16..2310-04-04
* 1 1 1 0x280000000..0x2ffffffff 0x300000000 2310-04-04..2378-04-22
* 1 1 0 0x300000000..0x37fffffff 0x300000000 2378-04-22..2446-05-10
Note that the time limits are not correct for deletion times.
Added a warn when an inode cannot be extended to incorporate an
extended timestamp.
Signed-off-by: Deepa Dinamani <deepa.kernel@xxxxxxxxx>
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
Cc: tytso@xxxxxxx
Cc: adilger.kernel@xxxxxxxxx
Cc: linux-ext4@xxxxxxxxxxxxxxx
---
fs/ext4/ext4.h | 10 +++++++++-
fs/ext4/super.c | 17 +++++++++++++++--
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 9c7f4036021b..ae5d0c86aba2 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -832,11 +832,15 @@ static inline void ext4_decode_extra_time(struct timespec64 *time,
#define EXT4_INODE_SET_XTIME(xtime, inode, raw_inode) \
do { \
- (raw_inode)->xtime = cpu_to_le32((inode)->xtime.tv_sec); \
if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra)) {\
+ (raw_inode)->xtime = cpu_to_le32((inode)->xtime.tv_sec); \
(raw_inode)->xtime ## _extra = \
ext4_encode_extra_time(&(inode)->xtime); \
} \
+ else {\
+ (raw_inode)->xtime = cpu_to_le32(clamp_t(int32_t, (inode)->xtime.tv_sec, S32_MIN, S32_MAX)); \
+ ext4_warning_inode(inode, "inode does not support timestamps beyond 2038"); \
+ } \
} while (0)
#define EXT4_EINODE_SET_XTIME(xtime, einode, raw_inode) \
@@ -1643,6 +1647,10 @@ static inline bool ext4_verity_in_progress(struct inode *inode)
#define EXT4_GOOD_OLD_INODE_SIZE 128
+#define EXT4_EXTRA_TIMESTAMP_MAX (((s64)1 << 34) - 1 + S32_MIN)
+#define EXT4_NON_EXTRA_TIMESTAMP_MAX S32_MAX
+#define EXT4_TIMESTAMP_MIN S32_MIN
+
/*
* Feature set definitions
*/
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 27cd622676e7..3db5f17228b7 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4039,8 +4039,21 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_inode_size);
goto failed_mount;
}
- if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE)
- sb->s_time_gran = 1 << (EXT4_EPOCH_BITS - 2);
+ /*
+ * i_atime_extra is the last extra field available for [acm]times in
+ * struct ext4_inode. Checking for that field should suffice to ensure
+ * we have extra space for all three.
+ */
+ if (sbi->s_inode_size >= offsetof(struct ext4_inode, i_atime_extra) +
+ sizeof(((struct ext4_inode *)0)->i_atime_extra)) {
+ sb->s_time_gran = 1;
+ sb->s_time_max = EXT4_EXTRA_TIMESTAMP_MAX;
+ } else {
+ sb->s_time_gran = NSEC_PER_SEC;
+ sb->s_time_max = EXT4_NON_EXTRA_TIMESTAMP_MAX;
+ }
+
+ sb->s_time_min = EXT4_TIMESTAMP_MIN;
}
sbi->s_desc_size = le16_to_cpu(es->s_desc_size);
--
2.17.1
