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由 Josef Bacik 提交于
In btrfs we have 2 indexes for inodes. One is for readdir, it's in this nice sequential order and works out brilliantly for readdir. However if you use ls, it usually stat's each file it gets from readdir. This is where the second index comes in, which is based on a hash of the name of the file. So then the lookup has to lookup this index, and then lookup the inode. The index lookup is going to be in random order (since its based on the name hash), which gives us less than stellar performance. Since we know the inode location from the readdir index, I create a dummy dentry and copy the location key into dentry->d_fsdata. Then on lookup if we have d_fsdata we use that location to lookup the inode, avoiding looking up the other directory index. Thanks, Signed-off-by: NJosef Bacik <josef@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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