Skip to contentSkip to conversation

ext4: Initialize timestamps limits

PATCH In review Deepa Dinamani 2 participants 2 messages Jun 18, 2019 – Jun 24, 2019 1 message not in the archive ext4 file system

lore
Share & tools
lore

A message that is not in the archive (sent off-list or not yet received): [email protected]

Deepa Dinamani

author
#1 lore raw

PATCH 8/16 ext4: Initialize timestamps limits

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.

Signed-off-by Deepa Dinamani <[email protected]>
Cc "Theodore Ts'o" <[email protected]>
Cc Andreas Dilger <[email protected]>
Cc [email protected]
---
 fs/ext4/ext4.h  |  4 ++++
 fs/ext4/super.c | 16 ++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)
fs/ext4/ext4.h +4 -0
index 1cb67859e051..3f13cf12ae7f 100644
@@ -1631,6 +1631,10 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
 
 #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
  */
fs/ext4/super.c +14 -2
index 4079605d437a..0357acdeb6d3 100644
@@ -4035,8 +4035,20 @@ 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 spaces 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 = 0;
+			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);
Signature · 1 line
2.17.1
Reviewed-by on v1 8/16
#2 lore raw
Quoted 20 lines · Deepa Dinamani

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
Quoted 4 lines

Note that the time limits are not correct for deletion times.

Signed-off-by Deepa Dinamani <[email protected]>
Cc "Theodore Ts'o" <[email protected]>
Reviewed-by Andreas Dilger <[email protected]>
Quoted 49 lines
Cc [email protected]

---
fs/ext4/ext4.h | 4 ++++
fs/ext4/super.c | 16 ++++++++++++++--

2 files changed, 18 insertions(+), 2 deletions(-)
fs/ext4/ext4.h +4 -0
index 1cb67859e051..3f13cf12ae7f 100644
@@ -1631,6 +1631,10 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
 
 #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
 */
fs/ext4/super.c +14 -3
index 4079605d437a..0357acdeb6d3 100644
@@ -4035,8 +4035,20 @@ 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 spaces 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 = 0;
+			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);
--
Quoted 2 lines

2.17.1

Cheers, Andreas