I've bisected the deadlock when many small appends are done on jffs2 down to
this commit:
commit 6fe6900e1e5b6fa9e5c59aa5061f244fe3f467e2
Author: Nick Piggin <npiggin@suse.de>
Date: Sun May 6 14:49:04 2007 -0700
mm: make read_cache_page synchronous
Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate calls.
I didn't have a great look down the call chains, but this appears to fixes 7
possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in
ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in
block2mtd. All depending on whether the filler is async and/or can return
with a !uptodate page.
It introduced a wait to read_cache_page, as well as a
read_cache_page_async function equivalent to the old read_cache_page
without any callers.
Switching jffs2_gc_fetch_page to read_cache_page_async for the old
behavior makes the deadlocks go away, but maybe reintroduces the
use-before-uptodate problem? I don't understand the mm/fs interaction
well enough to say.
Someone more knowledgable should see if similar deadlock issues may have
been introduced for other read_cache_page callers, including the other
two in jffs2.
Signed-off-by: Jason Lunz <lunz@falooley.org>
---
fs/jffs2/fs.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index 1d3b7a9..8bc727b 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -627,7 +627,7 @@ unsigned char *jffs2_gc_fetch_page(struct jffs2_sb_info *c,
struct inode *inode = OFNI_EDONI_2SFFJ(f);
struct page *pg;
- pg = read_cache_page(inode->i_mapping, offset >> PAGE_CACHE_SHIFT,
+ pg = read_cache_page_async(inode->i_mapping, offset >> PAGE_CACHE_SHIFT,
(void *)jffs2_do_readpage_unlock, inode);
if (IS_ERR(pg))
return (void *)pg;
-
