On Thu, Jun 26, 2008 at 01:19:51PM +0100, Jamie Lokier wrote: > Andreas Dilger wrote: > > > Is there a reason why fsync() before calling FIEMAP is unsuitable? > > > > This was added because the xfsbmap operation always did an fsync before > > returning the extents. I don't think it is strictly required, but it > > isn't harmful either. > > It's not harmful but suggests it might do something important - > e.g. provide atomicity between the fsync and getting extends. It does precisely that. > > > > * FIEMAP_FLAG_XATTR > > > > If this flag is set, the extents returned will describe the inodes > > > > extended attribute lookup tree, instead of it's data tree. > > > > > > What is this for? The meaning of the xattr tree sounds rather > > > filesystem specific to me. > > > > This is to return the location of the xattr blocks for the inode. > > Some filesystems will store xattrs as metadata - in exactly the same > as, say, the inode itself, it's permissions, mappings etc. > > I'm not sure why xattrs get special treatment, compared with a > hypothetical FIEMAP_FLAG_METADATA for example, indicating which > physical blocks contain the inode itself, or it's other auxiliary > information. Because xattrs tend to contain user data, not metadata? Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
