Messages in this thread | | | From | OGAWA Hirofumi <> | Subject | Re: [PATCH] fat: Editions to support fat_fallocate() | Date | Mon, 14 Jan 2008 04:49:46 +0900 |
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"Grant Likely" <grant.likely@secretlab.ca> writes:
> On 12/23/07, OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> wrote: >> "Grant Likely" <grant.likely@secretlab.ca> writes: >> > >> > However, digging further, when FALLOC_FL_KEEP_SIZE is set, I don't >> > think fat_cont_expand() has the behaviour that we want to implement. >> > When that flag is set, I think we simply want to add clusters >> > associated with the file to the FAT. We don't want to clear them or >> > map them into the page cache yet (that should be done when the >> > filesize is increased for real). >> > >> > I believe a call to fat_allocate_clusters() is all that is needed in >> > this case. Hirofumi, please correct me if I'm wrong. >> >> Right. And we need to care the limitation on FAT specification (compatibility). > > I not sure I fully understand what you mean. Can you please > elaborate? Are you referring to whether on not it will break other > FAT implementations if a file has more clusters allocated than it > needs? If so, how do we decide whether or not it is acceptable?
[Sorry for long delay. I was on vacation.]
Probably we need to check how Widnows behave in some situations.
E.g. if we store the longer cluster-chain than i_size (in the case of FALLOC_FL_KEEP_SIZE), the driver will be seen like corrupted files. Because we doesn't know the file is whether file was "fallocate" or not after reboot. At least, I think current linux implementation will detect it as corrupted file (filesystem).
So we have to handle somehow those situations. Also I think we'll need to more investigate problem like this.
Thanks. -- OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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