From d6db242bbd6d606fd5babf84355365096c528620 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Axel=20D=C3=B6rfler?= Date: Wed, 5 Nov 2008 21:37:28 +0000 Subject: [PATCH] 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 | 48 ++++++++---------------- 1 file changed, 15 insertions(+), 33 deletions(-) diff --git a/src/add-ons/kernel/file_systems/bfs/ToDo b/src/add-ons/kernel/file_systems/bfs/ToDo index 3b721cfec6..6dccb94ac5 100644 --- a/src/add-ons/kernel/file_systems/bfs/ToDo +++ b/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 + - ... -----