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-rw-r--r--Documentation/filesystems/porting9
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 7fcac6393cd..dfbcd1b00b0 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -385,3 +385,12 @@ Documentation/filesystems/vfs.txt for more details.
on many or all directory inodes on the way down a path walk (to check for
exec permission). These must now be rcu-walk aware (flags & IPERM_FLAG_RCU).
See Documentation/filesystems/vfs.txt for more details.
+
+--
+[mandatory]
+ In ->fallocate() you must check the mode option passed in. If your
+filesystem does not support hole punching (deallocating space in the middle of a
+file) you must return -EOPNOTSUPP if FALLOC_FL_PUNCH_HOLE is set in mode.
+Currently you can only have FALLOC_FL_PUNCH_HOLE with FALLOC_FL_KEEP_SIZE set,
+so the i_size should not change when hole punching, even when puching the end of
+a file off.