Nfs client writing a mapped page to the nfs server
nfs.aop.writepage
for_kupdate
a flag of writeback_control, indicates if it's a kupdate writeback
dev
device identifier
i_size
file length in bytes
page_index
offset within mapping, can used a page identifier and position identifier in the page frame
sb_flag
super block flags
ino
inode number
size
number of pages to be written in this execution
for_reclaim
a flag of writeback_control, indicates if it's invoked from the page allocator
i_state
inode state flags
__page
the address of page
i_flag
file flags
wsize
write size
The priority of wb is decided by the flags for_reclaim and for_kupdate.