On Tue, 2006-10-24 at 15:44 -0400, Theodore Tso wrote: > On Tue, Oct 24, 2006 at 11:59:28PM +1000, David Chinner wrote: > > That's the wrong way to look at it. if you want the userspace > > process to specify a location, then you should preallocate it first > > before doing anything else. There is no need to clutter a simple > > data mover interface with all sorts of unnecessary error handling. > > This is doable, but it adds a huge amount of complexity before we > could implement on-line defragmentation. > > First of all, we would need a way of allowing userpsace to specify > which blocks should be used in the preallocation. > > Secondly, we would need a way of marking blocks as "preallocated but > not pre-zeroed"; otherwise we would have to zero out all of the blocks > in order to assure security (don't want userspace programs seeing the > previous contents of the data blocks), only to do the copy and the > extents vector swap Chris Mason page place holder work for DIRECT IO should be applicable to any pre-allocations? -- Russell Cattelan <cattelan@xxxxxxxxxxx>
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