To: Christoph Hellwig <hch@...>, <linux-fsdevel@...>, <linux-kernel@...>, <linux-ext4@...>, <adilger@...>, David Chinner <dgc@...>, <suparna@...>, <cmm@...>, <xfs@...>
On Tue, Jul 03, 2007 at 11:31:07AM +0100, Christoph Hellwig wrote:
Well, if you see the modes proposed using above flags :
#define FA_ALLOCATE 0
#define FA_DEALLOCATE FA_FL_DEALLOC
#define FA_RESV_SPACE FA_FL_KEEP_SIZE
#define FA_UNRESV_SPACE (FA_FL_DEALLOC | FA_FL_KEEP_SIZE | FA_FL_DEL_DATA)
FA_FL_DEL_DATA is _not_ being used for preallocation. We have two modes
for preallocation FA_ALLOCATE and FA_RESV_SPACE, which do not use this
flag. Hence prealloction will never delete data.
This mode is required only for FA_UNRESV_SPACE, which is a deallocation
mode, to support any existing XFS aware applications/usage-scenarios.
And, regarding FA_FL_DEALLOC being a separate syscall - I think then the
very purpose of @mode argument is not justified. We have this mode so
that we can provide more features like this. That said, I don't say that
we should make things very complicated; but, atleast we should provide
some basic features which we expect most of the applications wanting
preallocation to use. To start with, we need to cater to already
existing applications/user base who use XFS preallocation feature.
And further advanced features, like goal based preallocation, can be
implemented as a separate syscall.
Ok. This can be changed in the next take.
I agree on this one.
This requirement was from the point of view of HSM applications. Hope
you saw Andreas previous post and are keeping that in mind.
--
Regards,
Amit Arora
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