fs/adfs: inode: update timestamps to centisecond precision
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>
diff --git a/fs/adfs/inode.c b/fs/adfs/inode.c
index 124de75..18a1d47 100644
--- a/fs/adfs/inode.c
+++ b/fs/adfs/inode.c
@@ -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?
