The Linux VFS and Ext4

The virtual file system interface sits right below Linux's implementation of the file I/O API defined by the file-related system calls. In this session, we will consider how the VFS abstracts out and supplies common operations.

major data structures
support for delegating operations to specific file system implementations
support for canonicalization and path lookup

The XFS file system: http://oss.sgi.com/projects/xfs/papers/xfs_usenix/index.html

$ history > ~/myhistory.txt
$ wc ~/myhistory.txt 
$ cat ~/myhistory.txt | sort | awk '{print $2}' | sort | uniq -c | sort -nr
670 ls
540 cd
462 make
280 emacs
217 pdflatex
213 clear
136 file
125 mv
114 open
107 grep
 99 more
 72 cat
 64 scp
 44 ssh
 39 mkdir
 37 ll
 30 man
 29 rm
 26 cvs
 19 exit
 17 cp
 16 ./doq
 15 wc
 15 sftp
 14 gawk
 12 pwd
 12 printf
 12 history
  7 unzip
  7 top
  7 sort
  7 amke
  6 df
  3 mail
  3 locate
  2 wget
  2 wall
  2 ssh-add
  2 mount
  2 doq
  1 which
  1 touch
  1 svn
  1 s
  1 rmdir
  1 pushd
  1 popd
  1 mesg
  1 mailx
  1 mai
  1 echo
  1 date
  1 chmod
  1 cal
$

sys_read entry point