Re: [PATCH v2] f2fs: relax migratepage for atomic written page

From: Jaegeuk Kim
Date: Thu Jul 06 2017 - 17:49:37 EST


In order to avoid lock contention for atomic written pages, we'd better give
EBUSY in f2fs_migrate_page when mode is asynchronous. We expect it will be
released soon as transaction commits.

Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---

Change log from v1:
- return -EBUSY when mode is MIGRATE_ASYNC or MIGRATE_SYNC_LIGHT

fs/f2fs/data.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 85ac3a63cce6..74c31cb203e2 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2206,8 +2206,12 @@ int f2fs_migrate_page(struct address_space *mapping,
BUG_ON(PageWriteback(page));

/* migrating an atomic written page is safe with the inmem_lock hold */
- if (atomic_written && !mutex_trylock(&fi->inmem_lock))
- return -EAGAIN;
+ if (atomic_written) {
+ if (mode != MIGRATE_SYNC)
+ return -EBUSY;
+ if (!mutex_trylock(&fi->inmem_lock))
+ return -EAGAIN;
+ }

/*
* A reference is expected if PagePrivate set when move mapping,
--
2.13.0.rc1.294.g07d810a77f-goog