• NeilBrown's avatar
    [PATCH] Fix some problems with truncate and mtime semantics. · 4a30131e
    NeilBrown authored
    SUS requires that when truncating a file to the size that it currently
      truncate and ftruncate should NOT modify ctime or mtime
      O_TRUNC SHOULD modify ctime and mtime.
    Currently mtime and ctime are always modified on most local
    filesystems (side effect of ->truncate) or never modified (on NFS).
    With this patch:
      ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when
        an update of these times is required whether size changes or not
        (via a new argument to do_truncate).  This allows NFS to do
        the right thing for O_TRUNC.
      inode_setattr nolonger forces ATTR_MTIME|ATTR_CTIME when the ATTR_SIZE
        sets the size to it's current value.  This allows local filesystems
        to do the right thing for f?truncate.
    Also, the logic in inode_setattr is changed a bit so there are two return
    points.  One returns the error from vmtruncate if it failed, the other
    returns 0 (there can be no other failure).
    Finally, if vmtruncate succeeds, and ATTR_SIZE is the only change
    requested, we now fall-through and mark_inode_dirty.  If a filesystem did
    not have a ->truncate function, then vmtruncate will have changed i_size,
    without marking the inode as 'dirty', and I think this is wrong.
    Signed-off-by: default avatarNeil Brown <neilb@suse.de>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
open.c 25.3 KB