The patch titled adfs: improve timestamp precision has been added to the -mm tree. Its filename is adfs-improve-timestamp-precision.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: adfs: improve timestamp precision From: Stuart Swales <stuart.swales.croftnuisk@xxxxxxxxx> ADFS (FileCore) storage complies with the RISC OS timestamp specification (40-bit centiseconds since 01 Jan 1900 00:00:00). It is desirable that stored timestamp precision be maintained to facilitate a precise copy of data and metadata from a hard disc (or image thereof) into a RISC OS emulator (such as RPCEmu). This patch implements a full-precision conversion from ADFS to Unix timestamp as the existing driver, for ease of calculation with old 32-bit compilers, uses the common trick of shifting the 40-bits representing centiseconds around into 32-bits representing seconds thereby losing precision. Signed-off-by: Stuart Swales<stuart.swales.croftnuisk@xxxxxxxxx> Cc: Russell King <rmk@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/adfs/inode.c | 42 ++++++++++++++++++++---------------------- 1 file changed, 20 insertions(+), 22 deletions(-) diff -puN fs/adfs/inode.c~adfs-improve-timestamp-precision fs/adfs/inode.c --- a/fs/adfs/inode.c~adfs-improve-timestamp-precision +++ a/fs/adfs/inode.c @@ -175,50 +175,48 @@ adfs_mode2atts(struct super_block *sb, s /* * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time - * referenced to 1 Jan 1900 (til 2248) + * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds + * of time to convert from RISC OS epoch to Unix epoch. */ static void adfs_adfs2unix_time(struct timespec *tv, struct inode *inode) { unsigned int high, low; + /* 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_I(inode)->stamped == 0) goto cur_time; - high = ADFS_I(inode)->loadaddr << 24; - low = ADFS_I(inode)->execaddr; + high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */ + low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */ - high |= low >> 8; - low &= 255; + /* convert 40-bit centi-seconds to 32-bit seconds + * going via nanoseconds to retain precision + */ + nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */ /* Files dated pre 01 Jan 1970 00:00:00. */ - if (high < 0x336e996a) + if (nsec < nsec_unix_epoch_diff_risc_os_epoch) goto too_early; - /* Files dated post 18 Jan 2038 03:14:05. */ - if (high >= 0x656e9969) - goto too_late; - - /* discard 2208988800 (0x336e996a00) seconds of time */ - high -= 0x336e996a; - - /* convert 40-bit centi-seconds to 32-bit seconds */ - tv->tv_sec = (((high % 100) << 8) + low) / 100 + (high / 100 << 8); - tv->tv_nsec = 0; + /* convert from RISC OS to Unix epoch */ + nsec -= nsec_unix_epoch_diff_risc_os_epoch; + + *tv = ns_to_timespec(nsec); return; cur_time: - *tv = CURRENT_TIME_SEC; + *tv = CURRENT_TIME; return; too_early: tv->tv_sec = tv->tv_nsec = 0; return; - - too_late: - tv->tv_sec = 0x7ffffffd; - tv->tv_nsec = 0; - return; } /* _ Patches currently in -mm which might be from stuart.swales.croftnuisk@xxxxxxxxx are adfs-fix-e-f-dir-size-2048-crashing-kernel.patch adfs-improve-timestamp-precision.patch adfs-add-hexadecimal-filetype-suffix-option.patch adfs-remove-the-big-kernel-lock.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html