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SubjectRe: [f2fs-dev] [PATCH 1/2 v2] f2fs: avoid deadlock caused by lock order of page and lock_op
- punch_hole
- fill_zero
- f2fs_lock_op
- get_new_data_page
- lock_page

- f2fs_write_data_pages
- lock_page
- do_write_data_page
- f2fs_lock_op

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---

Change log from v1:
- hide EAGAIN to users

fs/f2fs/data.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 72fc866cad19..7dd5fb647d43 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1404,8 +1404,9 @@ int do_write_data_page(struct f2fs_io_info *fio)
}
}

- if (fio->need_lock == LOCK_REQ)
- f2fs_lock_op(fio->sbi);
+ /* Deadlock due to between page->lock and f2fs_lock_op */
+ if (fio->need_lock == LOCK_REQ && !f2fs_trylock_op(fio->sbi))
+ return -EAGAIN;

err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
if (err)
@@ -1667,7 +1668,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
}

done_index = page->index;
-
+retry_write:
lock_page(page);

if (unlikely(page->mapping != mapping)) {
@@ -1703,6 +1704,15 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
unlock_page(page);
ret = 0;
continue;
+ } else if (ret == -EAGAIN) {
+ ret = 0;
+ if (wbc->sync_mode == WB_SYNC_ALL) {
+ cond_resched();
+ congestion_wait(BLK_RW_ASYNC,
+ HZ/50);
+ goto retry_write;
+ }
+ continue;
}
done_index = page->index + 1;
done = 1;
--
2.13.0.rc1.294.g07d810a77f-goog
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