don't pass nameidata to ->create()

[deliverable/linux.git] / Documentation / filesystems / porting

diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 74acd9618819b0adc61d13bfe82fee438f602c1f..2bef2b3843d1d4e09ead99fed121de4b2ab92db2 100644 (file)
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -297,7 +297,8 @@ in the beginning of ->setattr unconditionally.
 be used instead.  It gets called whenever the inode is evicted, whether it has
 remaining links or not.  Caller does *not* evict the pagecache or inode-associated
 metadata buffers; getting rid of those is responsibility of method, as it had
-been for ->delete_inode().
+been for ->delete_inode(). Caller makes sure async writeback cannot be running
+for the inode while (or after) ->evict_inode() is called.
 
        ->drop_inode() returns int now; it's called on final iput() with
 inode->i_lock held and it returns true if filesystems wants the inode to be
@@ -306,14 +307,11 @@ updated appropriately.  generic_delete_inode() is also alive and it consists
 simply of return 1.  Note that all actual eviction work is done by caller after
 ->drop_inode() returns.
 
-       clear_inode() is gone; use end_writeback() instead.  As before, it must
-be called exactly once on each call of ->evict_inode() (as it used to be for
-each call of ->delete_inode()).  Unlike before, if you are using inode-associated
-metadata buffers (i.e. mark_buffer_dirty_inode()), it's your responsibility to
-call invalidate_inode_buffers() before end_writeback().
-       No async writeback (and thus no calls of ->write_inode()) will happen
-after end_writeback() returns, so actions that should not overlap with ->write_inode()
-(e.g. freeing on-disk inode if i_nlink is 0) ought to be done after that call.
+       As before, clear_inode() must be called exactly once on each call of
+->evict_inode() (as it used to be for each call of ->delete_inode()).  Unlike
+before, if you are using inode-associated metadata buffers (i.e.
+mark_buffer_dirty_inode()), it's your responsibility to call
+invalidate_inode_buffers() before clear_inode().
 
        NOTE: checking i_nlink in the beginning of ->write_inode() and bailing out
 if it's zero is not *and* *never* *had* *been* enough.  Final unlink() and iput()
@@ -357,12 +355,10 @@ protects *all* the dcache state of a given dentry.
 via rcu-walk path walk (basically, if the file can have had a path name in the
 vfs namespace).
 
-       i_dentry and i_rcu share storage in a union, and the vfs expects
-i_dentry to be reinitialized before it is freed, so an:
-
-  INIT_LIST_HEAD(&inode->i_dentry);
-
-must be done in the RCU callback.
+       Even though i_dentry and i_rcu share storage in a union, we will
+initialize the former in inode_init_always(), so just leave it alone in
+the callback.  It used to be necessary to clean it there, but not anymore
+(starting at 3.2).
 
 --
 [recommended]
@@ -435,3 +431,14 @@ release it yourself.
        d_alloc_root() is gone, along with a lot of bugs caused by code
 misusing it.  Replacement: d_make_root(inode).  The difference is,
 d_make_root() drops the reference to inode if dentry allocation fails.  
+
+--
+[mandatory]
+       The witch is dead!  Well, 2/3 of it, anyway.  ->d_revalidate() and
+->lookup() do *not* take struct nameidata anymore; just the flags.
+--
+[mandatory]
+       ->create() doesn't take struct nameidata *; unlike the previous
+two, it gets "is it an O_EXCL or equivalent?" boolean argument.  Note that
+local filesystems can ignore tha argument - they are guaranteed that the
+object doesn't exist.  It's remote/distributed ones that might care...