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    SubjectRe: [RFC] Heads up on sys_fallocate()
    > >On Fri, 02 Mar 2007 09:40:54 +1100
    > >Nathan Scott <nscott@aconex.com> wrote:
    > >
    > >
    > >>On Thu, 2007-03-01 at 14:25 -0800, Andrew Morton wrote:
    > >>
    > >>>On Fri, 2 Mar 2007 00:04:45 +0530
    > >>>"Amit K. Arora" <aarora@linux.vnet.ibm.com> wrote:
    > >>>
    > >>>
    > >>>>This is to give a heads up on few patches that we will be soon coming up
    > >>>>with. These patches implement a new system call sys_fallocate() and a
    > >>>>new inode operation "fallocate", for persistent preallocation. The new
    > >>>>system call, as Andrew suggested, will look like:
    > >>>>
    > >>>> asmlinkage long sys_fallocate(int fd, loff_t offset, loff_t len);
    > >>>
    > >>>...
    > >>>
    > >>>I'd agree with Eric on the "command" flag extension.
    > >>
    > >>Seems like a separate syscall would be better, "command" sounds
    > >>a bit ioctl like, especially if that command is passed into the
    > >>filesystems..
    > >>
    > >
    > >
    > >madvise, fadvise, lseek, etc seem to work OK.
    > >
    > >I get repeatedly traumatised by patch rejects whenever a new syscall gets
    > >added, so I'm biased.
    > >
    > >The advantage of a command flag is that we can add new modes in the future
    > >without causing lots of churn, waiting for arch maintainers to catch up,
    > >potentially adding new compat code, etc.
    > >
    > >Rename it to "mode"? ;)
    > >
    > I am wondering if it is useful to add another mode to advise block
    > allocation policy? Something like indicating which physical block/block
    > group to allocate from (goal), and whether ask for strict contigous
    > blocks. This will help preallocation or reservation to choose the right
    > blocks for the file.
    Yes, I also think this would be useful so you can "guide"
    preallocation for things like defragmentation (e.g. preallocate space
    for the file being defragmented and move the file to it).

    Honza
    --
    Jan Kara <jack@suse.cz>
    SuSE CR Labs
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