Final answer:
In a log-structured file system, a new file /tmp/foo is created by allocating a new inode and logging the action. Data is appended to the log as it is written, and the inode is updated to reflect the final file size of 20 KB once writing is complete.
Step-by-step explanation:
When a process requests the creation of a new file /tmp/foo on a log-structured file system, several modifications occur. First, the system allocates a new inode for the file and records the creation in its log, a sequential structure meant to optimize write performance by appending all changes to the end of the log. As data is written sequentially to the file until it reaches 20 KB, the file system continuously appends these write operations to the log, ensuring data integrity and allowing for efficient use of disk bandwidth. The log structure is particularly adept at handling such sequential writes, as it minimizes seek times associated with traditional file systems.
Given the log-structured nature of the system, the writes are appended to the log in chunks, which are eventually coalesced during a garbage collection process that reclaims space used by obsolete or deleted files. This process is transparent to the user and is optimized to reduce the impact on system performance. Lastly, upon reaching the 20 KB file size, the system updates the file's inode with the latest size and metadata information, finalizing the operation.