[PATCH v5 2/6] f2fs: compress: fix to cover normal cluster write with cp_rwsem

[Chao Yu]

When we overwrite compressed cluster w/ normal cluster, we should
not unlock cp_rwsem during f2fs_write_raw_pages(), otherwise data
will be corrupted if partial blocks were persisted before CP & SPOR,
due to cluster metadata wasn't updated atomically.

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Reviewed-by: Daeho Jeong <daehojeong@xxxxxxxxxx>
Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
v5:
- include cleanup from Jaegeuk.
 fs/f2fs/compress.c | 27 ++++++++++++++++++---------
 fs/f2fs/data.c     |  3 ++-
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 9940b7886e5d..06e9bbfba1f1 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1443,12 +1443,14 @@ void f2fs_compress_write_end_io(struct bio *bio, struct page *page)
 }
 
 static int f2fs_write_raw_pages(struct compress_ctx *cc,
-					int *submitted,
+					int *submitted_p,
 					struct writeback_control *wbc,
 					enum iostat_type io_type)
 {
 	struct address_space *mapping = cc->inode->i_mapping;
-	int _submitted, compr_blocks, ret, i;
+	struct f2fs_sb_info *sbi = F2FS_M_SB(mapping);
+	int submitted, compr_blocks, i;
+	int ret = 0;
 
 	compr_blocks = f2fs_compressed_blocks(cc);
 
@@ -1463,6 +1465,10 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
 	if (compr_blocks < 0)
 		return compr_blocks;
 
+	/* overwrite compressed cluster w/ normal cluster */
+	if (compr_blocks > 0)
+		f2fs_lock_op(sbi);
+
 	for (i = 0; i < cc->cluster_size; i++) {
 		if (!cc->rpages[i])
 			continue;
@@ -1487,7 +1493,7 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
 		if (!clear_page_dirty_for_io(cc->rpages[i]))
 			goto continue_unlock;
 
-		ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted,
+		ret = f2fs_write_single_data_page(cc->rpages[i], &submitted,
 						NULL, NULL, wbc, io_type,
 						compr_blocks, false);
 		if (ret) {
@@ -1495,26 +1501,29 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
 				unlock_page(cc->rpages[i]);
 				ret = 0;
 			} else if (ret == -EAGAIN) {
+				ret = 0;
 				/*
 				 * for quota file, just redirty left pages to
 				 * avoid deadlock caused by cluster update race
 				 * from foreground operation.
 				 */
 				if (IS_NOQUOTA(cc->inode))
-					return 0;
-				ret = 0;
+					goto out;
 				f2fs_io_schedule_timeout(DEFAULT_IO_TIMEOUT);
 				goto retry_write;
 			}
-			return ret;
+			goto out;
 		}
 
-		*submitted += _submitted;
+		*submitted_p += submitted;
 	}
 
-	f2fs_balance_fs(F2FS_M_SB(mapping), true);
+out:
+	if (compr_blocks > 0)
+		f2fs_unlock_op(sbi);
 
-	return 0;
+	f2fs_balance_fs(sbi, true);
+	return ret;
 }
 
 int f2fs_write_multi_pages(struct compress_ctx *cc,
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 81f9e2cc49e2..b171a9980f6a 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2839,7 +2839,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 		.encrypted_page = NULL,
 		.submitted = 0,
 		.compr_blocks = compr_blocks,
-		.need_lock = LOCK_RETRY,
+		.need_lock = compr_blocks ? LOCK_DONE : LOCK_RETRY,
 		.post_read = f2fs_post_read_required(inode) ? 1 : 0,
 		.io_type = io_type,
 		.io_wbc = wbc,
@@ -2920,6 +2920,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 	if (err == -EAGAIN) {
 		err = f2fs_do_write_data_page(&fio);
 		if (err == -EAGAIN) {
+			f2fs_bug_on(sbi, compr_blocks);
 			fio.need_lock = LOCK_REQ;
 			err = f2fs_do_write_data_page(&fio);
 		}
-- 
2.40.1