Commit 2ca456c2 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

filemap: Update the folio_mark_dirty documentation 



The previous comment was not terribly helpful.  Be a bit more explicit
about the necessary locking environment.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
parent cd125eea

mm/page-writeback.c

+6 −4
Original line number Diff line number Diff line
@@ -2602,10 +2602,12 @@ EXPORT_SYMBOL(folio_redirty_for_writepage); 
 * folio_mark_dirty - Mark a folio as being modified.

 * @folio: The folio.

 *

 * For folios with a mapping this should be done with the folio lock held

 * for the benefit of asynchronous memory errors who prefer a consistent

 * dirty state. This rule can be broken in some special cases,

 * but should be better not to.

 * The folio may not be truncated while this function is running.

 * Holding the folio lock is sufficient to prevent truncation, but some

 * callers cannot acquire a sleeping lock.  These callers instead hold

 * the page table lock for a page table which contains at least one page

 * in this folio.  Truncation will block on the page table lock as it

 * unmaps pages before removing the folio from its mapping.

 *

 * Return: True if the folio was newly dirtied, false if it was already dirty.

 */