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ext4: Initialize timestamps limits

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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@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Acked-by: Jeff Layton <jlayton@kernel.org>
Cc: tytso@mit.edu
Cc: adilger.kernel@dilger.ca
Cc: linux-ext4@vger.kernel.org
This commit is contained in:
Deepa Dinamani
2018-01-21 18:04:24 -08:00
parent d5c6e2d518
commit 4881c4971d
2 changed files with 24 additions and 3 deletions
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17
fs/ext4/super.c
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@@ -4035,8 +4035,21 @@ 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);