On Fri, 2013-09-20 at 23:30 +0100, Hin-Tak Leung wrote: > -------------------------------------------- [snip] > > This patch implements functionality of creation > AttributesFile metadata file on HFS+ volume in the case of absence of it. > > It makes trying to open AttributesFile's B-tree during mount > of HFS+ volume. If HFS+ volume hasn't AttributesFile then a > pointer on AttributesFile's B-tree keeps as NULL. Thereby, when it > is discovered absence of AttributesFile on HFS+ volume in the > begin of xattr creation operation then AttributesFile will be > created. > > The creation of AttributesFile will have success in the case > of availability (2 * clump) free blocks on HFS+ volume. > Otherwise, creation operation is ended with error (-ENOSPC). [snip] > > The changelog isn't quite correct/precise. According to the code (my reading and > understanding of it), The AttributesFile is created on first need, i.e. when the first-ever > attribute is set. The changelog sounds as if an empty one might be created > if missing, on mount. The latter would be somewhat undesirable, as a user might > just keep a particular disk quite full but contain entirely of plain no-attribute files, and > have no need of a big AttributesFile ever, and suddenly find a disk throwing an previously-not-seen > error on use. > I don't think that description of the patch set is inaccurate. And I misunderstand how you can conclude from path set description that AttributesFile is created during mount operation. The patch description states that HFS+ driver tries to open AttributesFile's tree by means of hfs_btree_open() call (but such call takes place only if total blocks of AttributesFile doesn't equal to zero). So, hfs_btree_open() method doesn't contain any code of creation AttributesFile. And, finally, description of the patch states that AttributesFile creation functionality can be called in the begin of operation of extended attribute (xattr) creation, namely, in __hfsplus_setxattr() method. > Usage on linux would mostly be standalone xsetattr; the other common use would be > the copy of a file plus its attribute, from another fs which supports this, to an hfs+ fs without > a AttributesFile yet. How does hfs+ under Mac OS behaves vs current Linux vs patched Linux? > (silently dropping attribute/drop attribute with warning/error/etc ?) As far as I can judge, Mac OS X doesn't copy xattrs of files during copying operation. And, as far as I can see, Linux does it in the same way. Anyway, a file system driver should have some set of method for xattrs support. And HFS+ driver has all necessary methods (for xattrs support) as implemented. With the best regards, Vyacheslav Dubeyko. -- 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
