[PATCH v2 9/9] Documentation: document what to do on a writeback error

[Jeff Layton]

There's no real guidance on this for filesystem authors, so add a
paragraph to vfs.txt that explains how this should be handled.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 Documentation/filesystems/vfs.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 569211703721..527370fbab39 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -577,6 +577,13 @@ should clear PG_Dirty and set PG_Writeback.  It can be actually
 written at any point after PG_Dirty is clear.  Once it is known to be
 safe, PG_Writeback is cleared.
 
+If there is an error during writeback, then the address_space should be
+marked with an AS_EIO or AS_ENOSPC error, in order to ensure that the
+error will be reported to the application at fsync or close.  Most
+writepage callers will do this automatically if writepage returns an
+error, but writepages implementations generally need to ensure this
+themselves.
+
 Writeback makes use of a writeback_control structure...
 
 struct address_space_operations
-- 
2.9.3