From 4d7bf11d649c72621ca31b8ea12b9c94af380e63 Mon Sep 17 00:00:00 2001 From: Markus Rechberger Date: Tue, 8 May 2007 00:23:39 -0700 Subject: ext2/3/4: fix file date underflow on ext2 3 filesystems on 64 bit systems Taken from http://bugzilla.kernel.org/show_bug.cgi?id=5079 signed long ranges from -2.147.483.648 to 2.147.483.647 on x86 32bit 10000011110110100100111110111101 .. -2,082,844,739 10000011110110100100111110111101 .. 2,212,122,557 <- this currently gets stored on the disk but when converting it to a 64bit signed long value it loses its sign and becomes positive. Cc: Andreas Dilger Cc: Andreas says: This patch is now treating timestamps with the high bit set as negative times (before Jan 1, 1970). This means we lose 1/2 of the possible range of timestamps (lopping off 68 years before unix timestamp overflow - now only 30 years away :-) to handle the extremely rare case of setting timestamps into the distant past. If we are only interested in fixing the underflow case, we could just limit the values to 0 instead of storing negative values. At worst this will skew the timestamp by a few hours for timezones in the far east (files would still show Jan 1, 1970 in "ls -l" output). That said, it seems 32-bit systems (mine at least) allow files to be set into the past (01/01/1907 works fine) so it seems this patch is bringing the x86_64 behaviour into sync with other kernels. On the plus side, we have a patch that is ready to add nanosecond timestamps to ext3 and as an added bonus adds 2 high bits to the on-disk timestamp so this extends the maximum date to 2242. Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext2/inode.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/ext2') diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index dd4e14c221e0..9fa1bd65a028 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -1079,9 +1079,9 @@ void ext2_read_inode (struct inode * inode) } inode->i_nlink = le16_to_cpu(raw_inode->i_links_count); inode->i_size = le32_to_cpu(raw_inode->i_size); - inode->i_atime.tv_sec = le32_to_cpu(raw_inode->i_atime); - inode->i_ctime.tv_sec = le32_to_cpu(raw_inode->i_ctime); - inode->i_mtime.tv_sec = le32_to_cpu(raw_inode->i_mtime); + inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime); + inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime); + inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime); inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0; ei->i_dtime = le32_to_cpu(raw_inode->i_dtime); /* We now have enough fields to check if the inode was active or not. -- cgit v1.2.2