From: Andreas Gruenbacher <agruen@suse.de>

Andrew Morton found that there is lock contention between extended
attribute operations (like reading ACLs, which `ls -l' needs to do)
and other operations on the same files. This is due to the fact that
all extended attribute syscalls take inode->i_sem before calling into
the filesystem code.

To fix this problem, this patch no longer takes inode->i_sem in the
getxattr and listxattr syscalls, and moves the lock taking code into
the file systems. (Another patch improves the locking strategy in
ext2 and ext3.)