Messages in this thread | | | Date | Fri, 30 Sep 2005 08:36:30 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: truncate(2) sometimes updates ctime and sometimes ctime and mtime! |
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On Fri, 30 Sep 2005, Anton Altaparmakov wrote: > > There is an inconsistency in the way truncate works which was introduced > (relatively) recently. > > fs/open.c::sys_truncate > -> do_sys_truncate > -> do_truncate does: > > newattrs.ia_size = length; > newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME; > > down(&dentry->d_inode->i_sem); > err = notify_change(dentry, &newattrs); > up(&dentry->d_inode->i_sem); > > This changes the ctime only.
Hmm.. That looks wrong, partly because I don't think it should even set ATTR_CTIME _either_. However, I don't see any recent changes to that code, so it must have been logn for a long time. That line in do_truncate() has been like that since at _least_ 2002.
So what changed to make you notice?
The _code_ actually expects the low-level filesystem to just do it when it does the actual truncate itself. That's certainly what ext3 does, for example.
A comment or two to that effect might be useful, though.
In other words: some attributes are "implicit". For example, mtime is supposed to be set automatically by the filesystem whenever it sees a write. The VFS layer will _not_ do a "inode state notify" event for that.
The same is true of truncation.
But I agree that it's inconsistent. Anybody have any deep opinions?
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