Commit eeeb9dd9 authored by Russell King's avatar Russell King Committed by Al Viro
Browse files

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: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e42617b8

fs/adfs/inode.c

+20 −20
Original line number Diff line number Diff line
@@ -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?

fs/adfs/super.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

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