Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > On Tue, 17 Aug 2010, Valerie Aurora wrote: >> > - hard links to make sure a separate inode is not necessary for each >> > whiteout/fallthrough entry >> >> The problem with hard links is that you run into hard link limits. I >> don't think we can do hard links for whiteouts and fallthrus. Each >> whiteout or fallthru will cost an inode if we implement them as >> extended attributes. This cost has to be balanced against the cost of >> implementing them as dentries, which is mainly code complexity in >> individual file systems. Not knowing the details, I'd suggest to implement a generic function to create an attributed inode and let the fs override it to create an unlinked-file-dentry instead. Benefit: All fs supporting extended attributes will be able to support whiteout. If the fs has other means of supporting whiteout, they may fake the attribute. Possible problems: - Having two ways of reporting a whiteout? Or can it be reported using a (static) fake inode? - How do you un-whiteout while (not) having an overlaying fs? > get_unlinked_inode() is a great idea. But I feel that individual > inodes for each fallthrough is excessive. It'll make the first > readdir() really really expensive and wastes a lot of disk and memory > for no good reason. > > Not sure how to fix the hard link limits problem though... Do a hardlink if you can create a hard link, otherwise use a fresh inode and use that for the next hardlink(s). -- 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
