lkml.org 
[lkml]   [2007]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 4/7][TAKE5] support new modes in fallocate
    On Wed, Jul 11, 2007 at 10:03:12AM +0100, Christoph Hellwig wrote:
    > On Tue, Jul 03, 2007 at 05:16:50PM +0530, Amit K. Arora 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.
    >
    > Sorry, but this doesn't make any sense. There is no need to put every
    > feature in the XFS ioctls in the syscalls. The XFS ioctls will need to
    > be supported forever anyway - as I suggested before they really should
    > be moved to generic code.
    >
    > What needs to be supported is what makes sense as an interface.
    > A punch a hole interface does make sense, but trying to hack this into
    > a preallocation system call is just madness. We're not IRIX or windows
    > that fit things into random subcall just because there was some space
    > left to squeeze them in.
    >
    > > > > > FA_FL_NO_MTIME 0x10 /* keep same mtime (default change on size, data change) */
    > > > > > FA_FL_NO_CTIME 0x20 /* keep same ctime (default change on size, data change) */
    > > >
    > > > NACK to these aswell. If i_size changes c/mtime need updates, if the size
    > > > doesn't chamge they don't. No need to add more flags for this.
    > >
    > > This requirement was from the point of view of HSM applications. Hope
    > > you saw Andreas previous post and are keeping that in mind.
    >
    > HSMs needs this basically for every system call, which screams for an
    > open flag like O_INVISIBLE anyway. Adding this in a generic way is
    > a good idea, but hacking bits and pieces that won't fit into the global
    > design is completely wrong.


    Why don't we just merge the interface for preallocation (essentially
    enough to satisfy posix_fallocate() and the simple XFS requirement for
    space reservation without changing file size), which there is clear agreement
    on (I hope :)). After all, this was all that we set out to do when we
    started.

    And leave all the dealloc/punch/hsm type features for separate future patches/
    debates, those really shouldn't hold up the basic fallocate interface.
    I agree with Christoph that we are just diverging too much in trying to
    club those decisions here.

    Dave, Andreas, Ted ?

    Regards
    Suparna

    > -
    > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at http://vger.kernel.org/majordomo-info.html

    --
    Suparna Bhattacharya (suparna@in.ibm.com)
    Linux Technology Center
    IBM Software Lab, India

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-07-12 09:27    [W:0.043 / U:31.916 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site