[PATCH 2/6] iomap: IOMAP_DIOF_PGINVALID_FAIL return if page invalidation fails

[Goldwyn Rodrigues <rgoldwyn@suse.de>]

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

The flag indicates that if the page invalidation fails, it should return
back control to the filesystem so it may fallback to buffered mode.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/iomap/direct-io.c  | 8 +++++++-
 include/linux/iomap.h | 5 +++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 7ed857196a39..20c4370e6b1b 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -484,8 +484,14 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 	 */
 	ret = invalidate_inode_pages2_range(mapping,
 			pos >> PAGE_SHIFT, end >> PAGE_SHIFT);
-	if (ret)
+	if (ret) {
+		if (dio_flags & IOMAP_DIOF_PGINVALID_FAIL) {
+			if (ret == -EBUSY)
+				ret = 0;
+			goto out_free_dio;
+		}
 		dio_warn_stale_pagecache(iocb->ki_filp);
+	}
 	ret = 0;
 
 	if (iov_iter_rw(iter) == WRITE && !wait_for_completion &&
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index f6230446b08d..95024e28dec5 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -261,6 +261,11 @@ struct iomap_dio_ops {
 
 /* Wait for completion of DIO */
 #define IOMAP_DIOF_WAIT_FOR_COMPLETION 		0x1
+/*
+ * Return zero if page invalidation fails, so caller filesystem may fallback
+ * to buffered I/O
+ */
+#define IOMAP_DIOF_PGINVALID_FAIL		0x2
 
 ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
-- 
2.25.0