On Wednesday 18 June 2008 08:21, Andi Kleen wrote:It looks like mount does need an exact copy, so they've rolled their own (exact_copy_from_user). I guess if you need an exact copy, then it doesn't really matter how inexact an inexact one is, it's still unusable :) All else being equal, a smaller maximum error is preferable, but surely that is outweighed by the correctness issue of returning a valid number of bytes left to operate on. BTW. we already have lots (although steadily declining number) of corner case issues around this whole area, but if we want to get really strict, even an inexact report may be wrong for filemap. Suppose we copy 10 bytes into the pagecache, but report that 5 were copied. That means, we'll subsequently re-copy the delta. Between these two copies, a 2nd writer might come in and write something over those 5 bytes. Then a reader might see the following sequence of those 10 bytes "0000000000" "1111111111" "2222222222" "2222211111" --
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| Greg KH | [GIT PATCH] driver core patches against 2.6.24 |
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git: | |
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| Rob Coleman | S3 |
| Ian Kluft | 2nd CFV and VOTE ACK: comp.os.linux reorganization |
