On Fri 16-03-18 22:14:24, Tetsuo Handa wrote:
f2fs is doing
page = f2fs_pagecache_get_page(inode->i_mapping, 0, FGP_LOCK|FGP_NOWAIT, 0);
which calls
struct page *pagecache_get_page(inode->i_mapping, 0, FGP_LOCK|FGP_NOWAIT, 0);
. Then, can't we define
static inline struct page *find_trylock_page(struct address_space *mapping, pgoff_t offset) { return pagecache_get_page(mapping, offset, FGP_LOCK|FGP_NOWAIT, 0); }
and replace find_lock_page() with find_trylock_page() ?
I haven't checked whether we have enough users of this pattern to create a helper.
Also, won't
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 34ce3ebf..0cfc329 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -479,6 +479,8 @@ static inline int trylock_page(struct page *page) static inline void lock_page(struct page *page) { might_sleep();
- WARN_ONCE(current->flags & PF_MEMALLOC,
"lock_page() from reclaim context might deadlock");}
lock_page is called from many (semi)hot paths so I wouldn't add additional code there. Maybe we can hide it in VM_WARN. I would have to think much more to be sure this won't lead to some strange false positives. I suspect it won't but wouldn't bet my head on that.
In any case, you can try to send a patch and we can stick it into mmotm and have it there for few cycles to see what falls out...