Summary

The first part of this book, which included Chapters 1, 2, and 3, dealt with VFS and filesystems. The second part of this book, which constitutes Chapters 4, 5, and 6, is all about the block layer. This chapter introduced the role of the block layer in the Linux kernel. The block layer is the kernel subsystem and is in charge of managing I/O operations performed on block devices. The kernel’s block device interface is central to managing persistent storage on Linux. The user-space applications can access the block devices through block special devices in the /dev directory. Working with block devices is far more complicated than working with character devices, which can only work sequentially. Character devices have a single current position. Managing block devices is a far more complex task for the kernel as block devices must be able to move to any position to provide random access to data. Because of this, performance is a major concern when working with block devices...