1SB_START_PAGEFAULT(9)            The Linux VFS           SB_START_PAGEFAULT(9)
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NAME

6       sb_start_pagefault - get write access to a superblock from a page fault
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SYNOPSIS

9       void sb_start_pagefault(struct super_block * sb);
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ARGUMENTS

12       sb
13           the super we write to
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DESCRIPTION

16       When a process starts handling write page fault, it should embed the
17       operation into sb_start_pagefault - sb_end_pagefault pair to get
18       exclusion against file system freezing. This is needed since the page
19       fault is going to dirty a page. This function increments number of
20       running page faults preventing freezing. If the file system is already
21       frozen, the function waits until the file system is thawed.
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23       Since page fault freeze protection behaves as a lock, users have to
24       preserve ordering of freeze protection and other filesystem locks. It
25       is advised to put sb_start_pagefault close to mmap_sem in lock
26       ordering. Page fault
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HANDLING CODE IMPLIES LOCK DEPENDENCY

29       mmap_sem -> sb_start_pagefault
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32Kernel Hackers Manual 3.10         June 2019             SB_START_PAGEFAULT(9)
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