Messages in this thread |  | | Date | Mon, 28 Aug 2000 15:00:02 +0100 | From | "Stephen C. Tweedie" <> | Subject | Re: Some qns on Ext2 Extended File Attributes |
| |
Hi,
On Mon, Aug 28, 2000 at 09:23:00AM +0200, Michael Kerrisk wrote:
> if ( IS_NOATIME (inode) ) return; > > in update_atime(), and briefly looking at other parts of the source seems > to imply that this feature *is* present. However, a simple test (touch(1) > on a file with this attribute set) seems to indicate that this feature is > **not** implemented (since touch did change the file atime...). The > original poster of the earlier LK thread also found this attribute did not > seem to work. Have I missed something?
Yes. NOATIME only suppresses the automatic atime update when you read from a file. The timestamp is still there, even if it isn't being updated automatically. If you run touch(8) to set the atime manually, then the filesystem will still honour that request.
> EXT2_NODUMP_FL (chattr +d file) Do not backup file with dump(8) > > I ran a quick test with dump(8), and it seems to ignore this attribute > (i.e. files with this attribute got backed up anyway). Does this > attribute have any effect anywhere?
Yes. dump(8) has an option which lets you specify which level of dump will honour the NODUMP flag. By default, level 0 dumps ignore NODUMP, so that full dumps backup the entire filesystem but incremental dumps skip NODUMP files.
> EXT2_SYNC_FL (chattr +S file) Make file updates synchronous > > Either I'm misunderstanding how this attribute works or it doesn't seem to > be implemented. I had expected that setting this flag would force later > opens for writing on a file to behave as if O_SYNC had been specified.
No, it specifies that _directory_ updates are made synchronously. For file writes you still need to open them O_SYNC. The combination of O_SYNC (or fsync) on files, plus chattr +S on the directory, ensures that both the file _and_ the filename will be safe after reboot. O_SYNC on its own can only guarantee the data, not the filename, which is why the SYNC_FL attribute was added.
Cheers, Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
|  |