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fs/adfs: inode: update timestamps to centisecond precision

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Despite ADFS timestamps having centi-second granularity, and Linux
gaining fine-grained timestamp support in v2.5.48, fs/adfs was never
updated.

Update fs/adfs to centi-second support, and ensure that the inode ctime
always reflects what is written in underlying media.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Russell King 2019-12-09 11:08:18 +00:00 committed by Al Viro
parent e42617b825
commit eeeb9dd98e
2 changed files with 22 additions and 20 deletions
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40
fs/adfs/inode.c
View File

@ -158,6 +158,8 @@ adfs_mode2atts(struct super_block *sb, struct inode *inode)
return attr;
}
static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
/*
* Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time
* referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
@ -170,8 +172,6 @@ adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
/* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
* 01 Jan 1900 00:00:00 (RISC OS epoch)
*/
static const s64 nsec_unix_epoch_diff_risc_os_epoch =
2208988800000000000LL;
s64 nsec;
if (!adfs_inode_is_stamped(inode))
@ -204,24 +204,23 @@ adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
return;
}
/*
* Convert an Unix time to ADFS time. We only do this if the entry has a
* time/date stamp already.
*/
static void
adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
/* Convert an Unix time to ADFS time for an entry that is already stamped. */
static void adfs_unix2adfs_time(struct inode *inode,
const struct timespec64 *ts)
{
unsigned int high, low;
s64 cs, nsec = timespec64_to_ns(ts);
if (adfs_inode_is_stamped(inode)) {
/* convert 32-bit seconds to 40-bit centi-seconds */
low = (secs & 255) * 100;
high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
/* convert from Unix to RISC OS epoch */
nsec += nsec_unix_epoch_diff_risc_os_epoch;
ADFS_I(inode)->loadaddr = (high >> 24) |
(ADFS_I(inode)->loadaddr & ~0xff);
ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
}
/* convert from nanoseconds to centiseconds */
cs = div_s64(nsec, 10000000);
cs = clamp_t(s64, cs, 0, 0xffffffffff);
ADFS_I(inode)->loadaddr &= ~0xff;
ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
ADFS_I(inode)->execaddr = cs;
}
/*
@ -315,10 +314,11 @@ adfs_notify_change(struct dentry *dentry, struct iattr *attr)
if (ia_valid & ATTR_SIZE)
truncate_setsize(inode, attr->ia_size);
if (ia_valid & ATTR_MTIME) {
inode->i_mtime = attr->ia_mtime;
adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) {
adfs_unix2adfs_time(inode, &attr->ia_mtime);
adfs_adfs2unix_time(&inode->i_mtime, inode);
}
/*
* FIXME: should we make these == to i_mtime since we don't
* have the ability to represent them in our filesystem?

2
fs/adfs/super.c
View File

@ -391,7 +391,9 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
asb = kzalloc(sizeof(*asb), GFP_KERNEL);
if (!asb)
return -ENOMEM;
sb->s_fs_info = asb;
sb->s_time_gran = 10000000;
/* set default options */
asb->s_uid = GLOBAL_ROOT_UID;