In <1lrx1si.n8tms1igmi5pM%manu@xxxxxxxxxx> I explained why NetBSD currently fails self-heald.t, but since the subjet is burried deep in a thread, it might be worth starting a new one to talk about how to fix. In 3 places within glusterfs code (features/index, features/snapview-server and storage/posix), a server component answers readdir requests on a directory which may be split in mulitple calls. To answer one call, we have the following library calls: - opendir() - seekdir() to resume where the previous request was - readdir() - telldir() to record where we are for the next request - closedir() This relies on unspecified behavior, as POSIX says: "The value of loc should have been returned from an earlier call to telldir() using the same directory stream." http://pubs.opengroup.org/onlinepubs/9699919799/functions/seekdir.html Since we do opendir() and closedir() at each time, we do not use the same directory stream. It causes an infinite loop on NetBSD because it badly resume from previous request, and in the general case it will break badly if an entry is added in the directory between two requests. How can we fix that? 1) we can keep the directory stream open. The change is intrusive since we will need a chained list of open contexts, and we need to clean them if they timeout. 2) in order to keep state between requests, we can use the entry index (first encoutered is 1, and so on) instead of values returned by telldir(). That works around the unspecified behavior, but it still breaks if directory content is changed between two requests 3) make sure the readdir is done in a single request. That means trying with bigger buffers until it works. For instance in xlator/cluster/afr/src/afr-self-heald.c we have: while ((ret = syncop_readdir (subvol, fd, 131072, offset, &entries))) We would use -1 instead of 131072 to tell that we want everything without a size limit, and the server component (here features/index) would either return everyting or fail, whithout playing with telldir/seekdir. Opinions? The third solution seems the best to me since it is not very intrusive and it makes things simplier. Indeed we allow unbound data size to come back from the brick to glustershd, but we trust the brick, right? -- Emmanuel Dreyfus http://hcpnet.free.fr/pubz manu@xxxxxxxxxx _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxxx http://supercolony.gluster.org/mailman/listinfo/gluster-devel
