Messages in this thread |  | | Date | Thu, 11 Jan 2001 10:43:04 -0500 | From | Chris Mason <> | Subject | Re: Possible deadlock with ->writepaged version of flush_dirty_buffers() and 2.4.0 |
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On Wednesday, January 10, 2001 05:56:09 PM -0200 Marcelo Tosatti <marcelo@conectiva.com.br> wrote:
> > Hi Chris, > > It seems there is a possible deadlock condition with your patch which > changes flush_dirty_buffers() to use ->writepage (something which we > _definately_ want for 2.5). Take a look: > Yes, good catch.
> > mark_buffer_dirty->balance_dirty->wakeup_bdflush->flush_dirty_buffers-> > writepage->block_write_full_page->__block_write_full_page->get_block-> > ext2_get_block->ext2_alloc_branch-> > > ext2_alloc_block->ext2_new_block->lock_super > or > getblk()->lock_super > > > I dont see any reason why this deadlock could'nt happen in practice now. > It won't happen until someone other than fs/buffer.c starts marking ext2 pages dirty. The normal file write path will make sure that any dirty buffers are mapped, so the ext2_get_block code is never run.
> If I'm right, it will pretty nasty to fix this. One possible solution is > to _never_ call mark_buffer_dirty() with the superblock lock held (ext2 > has a lot of places likes this right now) >
This is probably the best solution, since it is a good idea regardless of my patch.
-chris
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