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Ts'o: Delayed allocation and the zero-length file problemTs'o: Delayed allocation and the zero-length file problemPosted Mar 15, 2009 23:25 UTC (Sun) by halfline (guest, #31920)In reply to: Ts'o: Delayed allocation and the zero-length file problem by alexl Parent article: Ts'o: Delayed allocation and the zero-length file problem
Another idea would be to introduce a new open flag, O_REWRITE, or some such that gives the same straightforwardness as O_TRUNC to the application developer but under the hood works on a detached file and atomically renames on close. Since all the I/O operations are grouped (via the fd), the kernel should be able to ensure proper ordering relatively easily (i think?) and apps wouldn't have to introduce a costly "sync it now" operation.
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Ts'o: Delayed allocation and the zero-length file problem Posted Mar 21, 2009 0:34 UTC (Sat) by spitzak (guest, #4593) [Link]
This flag certainly is needed, but I would go further and say that Linux should change the behavior of O_CREAT|O_WRONLY|O_TRUNC to do exactly what you specify. This is because probably every program using these flags (or using creat()) are written to implicitly expect this behavior anyway.
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