On 5/7/2010 9:53 AM, Matthew Wilcox wrote: > The problem you're seeing is aliasing in the page cache, not a failed > unification of the buffer and page caches. Pages are addressed by > (mapping, offset). Each inode generally has its own mapping. Depending > on the file system, directories may be addressed by their own inode's > mapping, or by the block device's mapping. If there are two mappings that don't know about each other, then the caches don't seem very unified to me. If I write to the file and that data sits in the mapping for the inode, then I read the corresponding blocks though the block device, and it has a different mapping, then I read the old data off the disk instead of the new data in the cache. I thought that this exact problem had been fixed long ago. > Resolving aliasing would be horribly expensive, so it's unlikely to > happen. Back to the drawing board I guess. Maybe ext could be fixed to use an inode mapping for directories instead of relying on the block device mapping, then I could readahead() the directory instead of having to go to the block device at all. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
