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Commit 3d08bcc8 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Al Viro
Browse files

mm: Wait for writeback when grabbing pages to begin a write 



When grabbing a page for a buffered IO write, the mm should wait for writeback
on the page to complete so that the page does not become writable during the IO
operation.  This change is needed to provide page stability during writes for
all filesystems.

Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 98702467

mm/filemap.c

+3 −1
Original line number Original line Diff line number Diff line
@@ -2327,7 +2327,7 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping, 
repeat:

repeat:

	page = find_lock_page(mapping, index);

	page = find_lock_page(mapping, index);

	if (page)

	if (page)

		return page;

		goto found;





	page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);

	page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);

	if (!page)

	if (!page)
@@ -2340,6 +2340,8 @@ repeat: 
			goto repeat;

			goto repeat;

		return NULL;

		return NULL;

	}

	}

found:

	wait_on_page_writeback(page);

	return page;

	return page;

}

}

EXPORT_SYMBOL(grab_cache_page_write_begin);

EXPORT_SYMBOL(grab_cache_page_write_begin);