Patchwork [1/2] mm: Wait for writeback when grabbing pages to begin a write

login
register
mail settings
Submitter Darrick J. Wong
Date May 27, 2011, 7:23 p.m.
Message ID <20110527192334.32105.99904.stgit@elm3c44.beaverton.ibm.com>
Download mbox | patch
Permalink /patch/97738/
State Not Applicable
Headers show

Comments

Darrick J. Wong - May 27, 2011, 7:23 p.m.
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: Darrick J. Wong <djwong@us.ibm.com>
---
 mm/filemap.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)



--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/mm/filemap.c b/mm/filemap.c
index bcdc393..dac95a2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2327,7 +2327,7 @@  struct page *grab_cache_page_write_begin(struct address_space *mapping,
 repeat:
 	page = find_lock_page(mapping, index);
 	if (page)
-		return page;
+		goto found;
 
 	page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
 	if (!page)
@@ -2340,6 +2340,8 @@  repeat:
 			goto repeat;
 		return NULL;
 	}
+found:
+	wait_on_page_writeback(page);
 	return page;
 }
 EXPORT_SYMBOL(grab_cache_page_write_begin);