Re: [libvirt] [PATCH v2 1/3] virfile: Refactor safezero, introduce virFileFdPosixFallocate
On Mon, Aug 11, 2014 at 04:30:19PM -0400, John Ferlan wrote:
Currently the safezero() function uses build conditionals to choose
either
the posix_fallocate() or mmap() with a fallback to safewrite() in order to
preallocate a file.
This patch will modify the logic in order to allow fallbacks in the
event that posix_fallocate() or the ftruncate()and mmap() doesn't work
properly. The fallback will be to use the slow safewrite of zero filled
buffers to the file.
Have you actually encountered failing of posix_fallocate() in the
real world ? It is supposed to automatically fallback to the
equivalent of writing zeros if the filesystem / kernel does not
support it, so we should not have todo runtime fallback ourselves.
The existance of fallback is the main distinction between the
posix_fallocate() and fallocate() system calls.
Regards,
Daniel
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