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Commit 543cc115 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
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documentation: document the is_dirty_writeback aops callback 



Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 26c0c5bf

Documentation/filesystems/vfs.txt

+10 −0
Original line number Diff line number Diff line
@@ -582,6 +582,7 @@ struct address_space_operations { 
	int (*launder_page) (struct page *);

	int (*is_partially_uptodate) (struct page *, read_descriptor_t *,

					unsigned long);

	void (*is_dirty_writeback) (struct page *, bool *, bool *);

	int (*error_remove_page) (struct mapping *mapping, struct page *page);

	int (*swap_activate)(struct file *);

	int (*swap_deactivate)(struct file *);
@@ -746,6 +747,15 @@ struct address_space_operations { 
	block is up to date then the read can complete without needing the IO

	to bring the whole page up to date.



  is_dirty_writeback: Called by the VM when attempting to reclaim a page.

	The VM uses dirty and writeback information to determine if it needs

	to stall to allow flushers a chance to complete some IO. Ordinarily

	it can use PageDirty and PageWriteback but some filesystems have

	more complex state (unstable pages in NFS prevent reclaim) or

	do not set those flags due to locking problems (jbd). This callback

	allows a filesystem to indicate to the VM if a page should be

	treated as dirty or writeback for the purposes of stalling.



  error_remove_page: normally set to generic_error_remove_page if truncation

	is ok for this address space. Used for memory failure handling.

	Setting this implies you deal with pages going away under you,