Hi, guys I got a question about this.Since htree is a potential limitation for subdirectories. Is there areason why EXT4_LINK_MAX is applied when fs hasn't dir_index butignored when fs has dir_index(by the following code)? #define is_dx(dir) (EXT4_HAS_COMPAT_FEATURE(dir->i_sb, \ EXT4_FEATURE_COMPAT_DIR_INDEX) && \ (EXT4_I(dir)->i_flags & EXT4_INDEX_FL))#define EXT4_DIR_LINK_MAX(dir) (!is_dx(dir) && (dir)->i_nlink >= EXT4_LINK_MAX) On Wed, Dec 24, 2008 at 9:18 AM, Zhang Xiliang<zhangxiliang@xxxxxxxxxxxxxx> wrote:> 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> -- Cheers, Bergwolf ................Rodney Dangerfield - "The way my luck is running, if I was apolitician I would be honest."��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
