centos man page for sb_start_pagefault

SB_START_PAGEFAULT(9)						   The Linux VFS					     SB_START_PAGEFAULT(9)

NAME
       sb_start_pagefault - get write access to a superblock from a page fault

SYNOPSIS
       void sb_start_pagefault(struct super_block * sb);

ARGUMENTS
       sb
	   the super we write to

DESCRIPTION
       When a process starts handling write page fault, it should embed the operation into sb_start_pagefault - sb_end_pagefault pair to get
       exclusion against file system freezing. This is needed since the page fault is going to dirty a page. This function increments number of
       running page faults preventing freezing. If the file system is already frozen, the function waits until the file system is thawed.

       Since page fault freeze protection behaves as a lock, users have to preserve ordering of freeze protection and other filesystem locks. It
       is advised to put sb_start_pagefault close to mmap_sem in lock ordering. Page fault

HANDLING CODE IMPLIES LOCK DEPENDENCY
       mmap_sem -> sb_start_pagefault

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						     SB_START_PAGEFAULT(9)