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-rw-r--r--Documentation/filesystems/porting27
1 files changed, 24 insertions, 3 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 6e29954851a2..7f8861d341ea 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -400,10 +400,31 @@ a file off.
--
[mandatory]
-
---
-[mandatory]
->get_sb() is gone. Switch to use of ->mount(). Typically it's just
a matter of switching from calling get_sb_... to mount_... and changing the
function type. If you were doing it manually, just switch from setting ->mnt_root
to some pointer to returning that pointer. On errors return ERR_PTR(...).
+
+--
+[mandatory]
+ ->permission(), generic_permission() and ->check_acl() have lost flags
+argument; instead of passing IPERM_FLAG_RCU we add MAY_NOT_BLOCK into mask.
+ generic_permission() has also lost the check_acl argument; if you want
+non-NULL to be used for that inode, put it into ->i_op->check_acl.
+
+--
+[mandatory]
+ If you implement your own ->llseek() you must handle SEEK_HOLE and
+SEEK_DATA. You can hanle this by returning -EINVAL, but it would be nicer to
+support it in some way. The generic handler assumes that the entire file is
+data and there is a virtual hole at the end of the file. So if the provided
+offset is less than i_size and SEEK_DATA is specified, return the same offset.
+If the above is true for the offset and you are given SEEK_HOLE, return the end
+of the file. If the offset is i_size or greater return -ENXIO in either case.
+
+[mandatory]
+ If you have your own ->fsync() you must make sure to call
+filemap_write_and_wait_range() so that all dirty pages are synced out properly.
+You must also keep in mind that ->fsync() is not called with i_mutex held
+anymore, so if you require i_mutex locking you must make sure to take it and
+release it yourself.