Re: [RFC][PATCH] ChunkFS: fs fission for faster fsck

From: Amit Gud
Date: Thu Apr 26 2007 - 12:46:43 EST

Alan Cox wrote:
Preventive measures are taken to limit only one continuation inode per file per chunk. This can be done easily in the chunk allocation algorithm for disk space. Although I'm not quite sure what you mean by

How are you handling the allocation in this situation, are you assuming
that a chunk is "out of bounds" because part of a file already lives on
it or simply keeping a single inode per chunk which has multiple sparse
pieces of the file on it ?

ie if I write 0-8MB to chunk A and then 8-16 to chunk B can I write
16-24MB to chunk A producing a single inode of 0-8 16-24, or does it have
to find another chunk to use ?

Hello Alan,

You re-use the same inode with multiple sparse pieces.

This way you avoid hopping around continuation inodes and coming back to same chunk with which you started but this time on a different continuation inode. This may not be I/O intensive for successive traversals if the continuation inodes are pinned in the memory, but it certainly is a waste of resource - inodes. Not allowing this would make worst case of every file having a continuation inode in every chunk, even worse; may be like only single file exist in the file system and rest all inodes in all chunks (including file's own chunk) are continuation inodes.

May the source be with you.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at