Theodore Tso 写道:
So that's not it. The problem is that indexed diretories have a limit that only allows the trees to be two levels deep. The fanout is normally big enough that this is effectively not a problem, but if you use very long filenames, and a 1k blocksize, you will run into this limit much more quickly. So the problem is not the number of sub directories, but the maximum depth of the htree allowed in Daniel Phillips' relatively restricted implementation. Note that with a 4k block filesystem, the limits get expanded by a factor of 4 cubed, or 64. And most of the time users aren't maximal length named directory entries, which further pushes the limit out in the normal case. It in theory would be possible to relax this restriction, using a more advanced htree implementation and a feature flag to allow backwards compatibility with older kernels that only support the maximal depth. Andreas has a prototype kernel implementation which in theory could be added to ext4. It hasn't been high on my priority list to complete, but if someone else really finds this limit to be annoying, it is a project they might try to complete. Were you writing this test program because this is a realistic situation for your application, or just to explore the limits of ext4?
Thanks for explanation. I see the limit of ext4 subdirectory. The test program originally tests it. But I fail and find the limit of the htree. I think it may be annoying. Somebody may be puzzled for the two limits. The limit of the htree should be greater than the limit of ext4 subdirectory. -- Regards Zhang Xiliang -- 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
