probe::nfs.fop.sendfile — NFS client send file operation
nfs.fop.sendfile
cache_valid
cache related bit mask flag
cache_time
when we started read-caching this inode
count
read bytes
dev
device identifier
ino
inode number
ppos
current position of file
attrtimeo
how long the cached information is assumed to be valid. We need to revalidate the cached attrs for this inode if jiffies - read_cache_jiffies > attrtimeo.