Surprisingly not: https://ext4.wiki.kernel.org/index.php/Frequently_Asked_Questions#History_of_ext2.2C_ext3.2C_and_ext4 https://ext4.wiki.kernel.org/index.php/F

Surprisingly not: https://ext4.wiki.kernel.org/index.php/Frequently_Asked_Questions#History_of_ext2.2C_ext3.2C_and_ext4 https://ext4.wiki.kernel.org/index.php/Frequently_Asked_Ques... http://www.geeksofpune.in/drupal/files/8058778-ext34talk.pdf http://www.geeksofpune.in/drupal/files/8058778-ext34talk.pdf ext2,3 used an indirect-block tree structure. Ext4 uses an extents system which is nicer, but still not (AFAIK, I've only skimmed this part) a B tree.