On Thu, Apr 26, 2007 at 12:05:04PM -0400, Jeff Dike wrote: > > No, I'm referring to a different file. The scenario is that you have > a growing file in a nearly full disk with files being deleted (and > thus space being freed) such that allocations for the growing file > bounce back and forth between chunks.
This is an excellent question. I call this the ping-pong problem. The solution is as Amit describes: You have a maximum of one continuation inode per file per chunk, and you require sparse files. Here's an example, spelled out: Allocate file 1 in chunk A. Grow file 1. Chunk A fills up. Allocate continuation inode for file 1 in chunk B. Chunk A gets some free space. Chunk B fills up. Pick chunk A for allocating next block of file 1. Try to look up a continuation inode for file 1 in chunk A. Continuation inode for file 1 found in chunk A! Attach newly allocated block to existing inode for file 1 in chunk A. This is why the file format inside each chunk needs to support sparse files. I have a presentation that has a series of slides on problems and potential resolutions that might help: http://infohost.nmt.edu/~val/review/chunkfs_presentation.pdf -VAL - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
