[PATCH RFC v2 11/13] udf: sync inode metadata in udf_evict_inode()

[Christian Brauner <brauner@kernel.org>]

udf_write_inode() copies the inode into the block that holds it, marks
the block dirty and sets I_METADATA_WRITEBACK so that a later fsync()
writes the block out and waits for it. But the bit goes away with the
inode. If the inode is evicted and read back in, fsync() finds a clean
inode and returns while the block might still be dirty or under
writeback.

Right now that can't happen because inode_lru_isolate() never lets go
of an inode with I_METADATA_WRITEBACK set. That is about to change.

So call udf_sync_inode_metadata() from udf_evict_inode() for an inode
that isn't deleted and still has the bit set. It syncs the metadata
buffers as well so it replaces the mmb_sync() there, and since the
previous patch it doesn't allocate anything.

Suggested-by: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org # v7.3
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 fs/udf/inode.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index b3e7c07cb9e7..8f45133ce75a 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -152,8 +152,18 @@ void udf_evict_inode(struct inode *inode)
 		}
 	}
 	truncate_inode_pages_final(&inode->i_data);
-	if (!want_delete)
-		mmb_sync(&iinfo->i_metadata_bhs);
+	if (!want_delete) {
+		/*
+		 * fsync() can't find what I_METADATA_WRITEBACK tracks once the
+		 * inode is gone. This syncs the metadata buffers as well.
+		 */
+		if (inode_state_read_once(inode) & I_METADATA_WRITEBACK)
+			udf_sync_inode_metadata(inode, &(struct writeback_control) {
+				.sync_mode = WB_SYNC_ALL,
+			});
+		else
+			mmb_sync(&iinfo->i_metadata_bhs);
+	}
 	mmb_invalidate(&iinfo->i_metadata_bhs);
 	clear_inode(inode);
 	kfree(iinfo->i_data);

-- 
2.53.0