On 20-Oct-09, at 14:49, Steve French wrote:
On Tue, Oct 20, 2009 at 3:33 PM, Andreas Dilger <adilger@xxxxxxx> wrote:For those users/admins that want to be able to change this (due to Samba, or whatever), great, we can give them this ability, but for users who do NOT want regular users to be able to change the file creation timestamp, that should be possible as well.So, are we ready for Mingming or one of the ext4 developers to propose a patch for this via xattrs (I can do a similar one for cifs). Sounds like various have said: 1) xattrs instead of ioctl2) get of create time allowed by default, but set of create time limited
A wildly untested/uncompiled patch is attached for purposes of discussion. One issue that I've already come across is if we are storing a raw "timespec" we will get different xattrs on disk in the fallback case where the on- disk
inodes are not large enough to store the crtime inside the inode. This version of the patch will fall back to storing the timespec on diskin the supplied size/endianness as an xattr, but it definitely needs to be handled more appropriately (endian/word size). It _would_ be nice to store a full 64-bit timespec on disk, but given that the in-inode format only can handle 34 bits of seconds + 30 bits of nanoseconds, it isn't clear whether
the "fallback" should do better than that. The main question is whether storing a "user.crtime" as an on-disk xattr is a desirable fallback, or if this should just fail? Similarly, should the lack of on-disk crtime return "0.0" as the creation time, or should it return -ENODATA or similar? Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.
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