Is there any good literature explaining Linux's file system ?

[Yubin Ruan]

     Hi everybody,
     I'm really curious about whether there is any literature that 
describe Linux's file systems(e.g. ext2{3,4}, btrfs) deeply?
     I can't find much literature about Linux's filesystem. I have read 
some papers about Unix's file system. For example, **A Fast File System 
for UNIX**, which explain things in detail(though not so informative for 
me). I also read **Design and Implementation of the Second Extend 
Filesystem** by Remy, Theodore, et al. But those papers and blogs can't 
make thing clear for me, because there are so many things that they have 
not explained.
     I wonder is there any book that explain one of the Linux 
filesystem(design, implementation) in detail, like what Mal Gorman 
explain about Linux Memory Management in his books **Understand The 
Linux Memory Manager** and **Code Commentary On The Linux Virtual Memory 
Manager** ?

Thanks in advance,
Ruan.