Brought ToDo file more or less up to date again.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@28522 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/file_systems/bfs/ToDo

@@ -1,39 +1,21 @@
-BFS - ToDo, November 12th, 2004
+BFS - ToDo, November 5th, 2008
 -----
 
 BlockAllocator
 
- - the BlockAllocator is only slightly optimized and probably slow
- - the first free and the largest range are currently not correctly maintained (only efficiency suffers - it does work correctly)
+ - the BlockAllocator is only slightly optimized
  - the allocation policies will have to stand against some real world tests
- - the access to the block bitmap is currently managed using a global lock (doesn't matter as long as transactions are serialized)
 
 
 DataStream
 
- - only files are trimmed back (in bfs_close()), but every inode has a preallocated stream...
  - Inode::GrowStream(): merging of block_runs doesn't work between range/block boundaries
- - check the array block size in BFS for different block sizes
 
 
 Queries
 
  - There shouldn't be any cases where you can speed up a query with reordering the query expression - test it
- - Check permissions of the parent directories
- - Add protection against crashing applications which had a query open - at least the original BeOS kernel does not free the cookie (which throws some memory away *and* prevents unmounting the disk), but that won't be needed for OpenBeOS
- - the query set for "!=" and last_modified/size is not the same as for "="; last_modified/size don't contain directories
  - check if the query has to be checked for a live update
- - accept hex values 0x...
-
-
-Journal
-
- - Check if there are any standard and often-happening cases for a transaction to fail, and if so, start the transaction only when necessary
- - if the system crashes between bfs_unlink() and bfs_remove_vnode(), the inode can be removed from the tree, but its memory is still allocated - this can happen if the inode is still in use by someone (and that's what the "chkbfs" utility is for, mainly).
- - add delayed index updating (+ delete actions to solve the issue above)
- - multiple log files, parallel transactions? (note that parallel transactions would require more locking to be done)
- - variable sized log file
- - as long as we have a fixed-sized log file, it should be possible to reserve space for a transaction to be able to decide if batching it is possible
 
 
 BPlusTree
@@ -49,7 +31,6 @@ Inode
  - exchange Inode::OldLastModified() with Inode::NewLastModified(), and don't change the last_modified field directly in Inode::WriteAt() for consistency in case of a crash
  - the size is only updated in bfs_close() - but if the system crashes before, the entry in the size index doesn't match the one in the inode anymore - it would be better to let the data.size not reflect the real file size in this case (since the max_xxx_range entries are always correct)
  - Inode::FillGapWithZeros() currently disabled; apart from being slow, it really shouldn't be executed while a transaction is running, because that stops all other threads from doing anything (which can be a long time for a 100 MB file)
- - need better locking mechanism in combination with B+trees etc.!
 
 
 Indices
@@ -58,24 +39,25 @@ Indices
  - clearing up Index::Update() and live query update (seems to be a bit confusing right now)
  - investigate adding an index cache to improve performance
 
+
 Attributes
 
- - Inode::WriteAttribute() doesn't check if the attribute data may fit into the small_data region if there already is that attribute as an attribute file
  - for indices, we could get the old data from there when doing a query update
+ - "pos" is ignored when writing attributes in the small data section (reading works)
 
 
-Volume
+Future BFS
 
-
-kernel_interface
-
- - missing functions, maybe they are not really needed: bfs_rename_attr(), bfs_rename_index(), bfs_initialize(), bfs_link()
- - bfs_rename() currently doesn't respect any permissions
-
-
-general stuff
-
- - There are also some comments with a leading "ToDo:" directly in the code which may not be mentioned here.
+ - put more than just an inode into a block
+ - make query indices useful for user oriented queries (*[Hh][Oo][Ww]?*)
+ - delayed allocation to be able to make better block allocation decisions
+ - if the system crashes between bfs_unlink() and bfs_remove_vnode(), the inode can be removed from the tree, but its memory is still allocated - this can happen if the inode is still in use by someone (and that's what the "chkbfs" utility is for, mainly).
+ - add delayed index updating (+ delete actions to solve the issue above)
+ - multiple log files, parallel transactions? (note that parallel transactions would require more locking to be done)
+ - variable sized log file
+ - the access to the block bitmap is currently managed using a global lock (doesn't matter as long as transactions are serialized)
+ - Check permissions of the parent directories for query results
+ - ...
 
 
 -----