Bruce, On 29.12.2016 17:15, J. Bruce Fields wrote: > On Thu, Dec 29, 2016 at 04:49:54PM +0100, Richard Weinberger wrote: >> Bruce, >> >> On 29.12.2016 16:34, J. Bruce Fields wrote: >>>> That way UBIFS can provide a 64bit readdir() cookie which is required for NFS3. >>> >>> Sounds good. And if a matching entry isn't found (as in the case of a >>> concurrent unlink), what happens? The answer must be the same as for >>> ext4, but I've forgotten the details.... I guess it must find the next >>> highest cookie (thinking of the cookie as a 64-bit integer of some kind) >>> that exists in the directory. And that must be the same order that >>> readdir normally returns entries in. >> >> If a 64bit cookie is not found, the lookup function returns -ENOENT. >> In UBIFS we cannot just select a higher or lower key (cookie in this case), >> since it is the B-tree key and would point to a completely different >> entry. >> >> So, in case of a concurrent unlink() one would succeed and one fail with >> -ENOENT. Unless I miss something that seems okay to me. > > Unlink takes (parent directory, name), not a directory cookie. > > The problem is concurrent unlink and nfs readdir. So: > > NFS server returns readdir result with cookie X > > Somebody unlinks the entry at X. > > NFS server gets readdir request with cookie X. > > Then the NFS client will get a spurious -ENOENT. Ah yes. Sorry I misunderstood your question. UBIFS readdir() address this already, if you ask it to readdir() from pos X and X is not present it will jump to the next best entry X'. UBIFS does so since ever. Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
