projects/linux·commit 6ccfa806

VFS: fix dio write returning EIO when try_to_release_page fails

6ccfa806 · Hisashi Hifumi <[email protected]> · 2008-09-02 14:35:40 -07:00

Dio write returns EIO when try_to_release_page fails because bh is
still referenced.

The patch

    commit 3f31fddfa26b7594b44ff2b34f9a04ba409e0f91
    Author: Mingming Cao <[email protected]>
    Date:   Fri Jul 25 01:46:22 2008 -0700

        jbd: fix race between free buffer and commit transaction

was merged into 2.6.27-rc1, but I noticed that this patch is not enough
to fix the race.

I did fsstress test heavily to 2.6.27-rc1, and found that dio write still
sometimes got EIO through this test.

The patch above fixed race between freeing buffer(dio) and committing
transaction(jbd) but I discovered that there is another race, freeing
buffer(dio) and ext3/4_ordered_writepage.

: background_writeout()
     ->write_cache_pages()
       ->ext3_ordered_writepage()
     	   walk_page_buffers() -> take a bh ref
 	   block_write_full_page() -> unlock_page
		: <- end_page_writeback
                : <- race! (dio write->try_to_release_page fails)
      	   walk_page_buffers() ->release a bh ref

ext3_ordered_writepage holds bh ref and does unlock_page remaining
taking a bh ref, so this causes the race and failure of
try_to_release_page.

To fix this race, I used the approach of falling back to buffered
writes if try_to_release_page() fails on a page.

[[email protected]: cleanups]
Signed-off-by: Hisashi Hifumi <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Mingming Cao <[email protected]>
Cc: Zach Brown <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Commit
6ccfa806a9cfbbf1cd43d5b6aa47ef2c0eb518fd
Parents
344c790e

Changes

2 files changed · +11 −4

FileStatusAddDelContent
mm/filemap.cmodified+9−2View file
mm/truncate.cmodified+2−2View file

mm/filemap.c

View file
diff --git a/mm/filemap.c b/mm/filemap.c
index 54e9686..876bc59 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2129,13 +2129,20 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
* After a write we want buffered reads to be sure to go to disk to get
* the new data. We invalidate clean cached page from the region we're
* about to write. We do this *before* the write so that we can return
- * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
+ * without clobbering -EIOCBQUEUED from ->direct_IO().
*/
if (mapping->nrpages) {
written = invalidate_inode_pages2_range(mapping,
pos >> PAGE_CACHE_SHIFT, end);
- if (written)
+ /*
+ * If a page can not be invalidated, return 0 to fall back
+ * to buffered write.
+ */
+ if (written) {
+ if (written == -EBUSY)
+ return 0;
goto out;
+ }
}
written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);

mm/truncate.c

View file
diff --git a/mm/truncate.c b/mm/truncate.c
index 2505050..6650c1d 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -380,7 +380,7 @@ static int do_launder_page(struct address_space *mapping, struct page *page)
* Any pages which are found to be mapped into pagetables are unmapped prior to
* invalidation.
*
- * Returns -EIO if any pages could not be invalidated.
+ * Returns -EBUSY if any pages could not be invalidated.
*/
int invalidate_inode_pages2_range(struct address_space *mapping,
pgoff_t start, pgoff_t end)
@@ -440,7 +440,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
ret2 = do_launder_page(mapping, page);
if (ret2 == 0) {
if (!invalidate_complete_page2(mapping, page))
- ret2 = -EIO;
+ ret2 = -EBUSY;
}
if (ret2 < 0)
ret = ret2;