[PATCH 5/5] zonefs: drain in-flight DIO before buffered writes

[Jiale Yao]

Conventional zone files allow both direct and buffered writes. An
asynchronous direct write can remain active after its submitting thread
releases the inode lock. A buffered write can then dirty page cache before
direct I/O completion performs post-write invalidation, causing the
invalidation to fail and record -EIO in the mapping error sequence.

After taking the exclusive inode lock, wait for active DIO before running
buffered write checks. Return -EAGAIN when an IOCB_NOWAIT request would
otherwise block.

Fixes: 4008e2a0b01a ("zonefs: Reorganize code")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
---
 fs/zonefs/file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/zonefs/file.c b/fs/zonefs/file.c
index 5b34849be7a2..8635a795c24c 100644
--- a/fs/zonefs/file.c
+++ b/fs/zonefs/file.c
@@ -576,6 +576,14 @@ static ssize_t zonefs_file_buffered_write(struct kiocb *iocb,
 		inode_lock(inode);
 	}
 
+	if (atomic_read(&inode->i_dio_count)) {
+		if (iocb->ki_flags & IOCB_NOWAIT) {
+			ret = -EAGAIN;
+			goto inode_unlock;
+		}
+		inode_dio_wait(inode);
+	}
+
 	ret = zonefs_write_checks(iocb, from);
 	if (ret <= 0)
 		goto inode_unlock;
-- 
2.34.1