fallocate system call

This is the latest fallocate patchset and is rebased to 2.6.22.

Following are the changes from TAKE5:
1) Rebased to 2.6.22
2) Added compat wrapper for x86_64
3) Dropped s390 and ia64 patches, since the platform maintaners can
   add the support for fallocate once it is in mainline.
4) Added a change suggested by Andreas for better extent-to-group
   alignment in ext4 (Patch 6/6). Please refer following post:
http://www.mail-archive.com/linux-ext4@vger.kernel.org/ms...
5) Renamed mode flags and values from "FA_" to "FALLOC_"
6) Added manpage (updated version of the one initially submitted by
   David Chinner).


Todos:
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1> Implementation on other architectures (other than i386, x86_64,
   and ppc64). s390(x) and ia64 patches are ready and will be pushed
   by platform maintaners when the fallocate is in mainline.
2> A generic file system operation to handle fallocate
   (generic_fallocate), for filesystems that do _not_ have the fallocate
   inode operation implemented.
3> Changes to glibc,
   a) to support fallocate() system call
   b) to make posix_fallocate() and posix_fallocate64() call fallocate()
4> A testcase to test the system call. Will post it soon.


Following patches follow:
Patch 1/7 : manpage for fallocate
Patch 2/7 : fallocate() implementation in i386, x86_64 and powerpc
Patch 3/7 : support new modes in fallocate
Patch 4/7 : ext4: fallocate support in ext4
Patch 5/7 : ext4: write support for preallocated blocks
Patch 6/7 : ext4: support new modes in ext4
Patch 7/7 : ext4: change for better extent-to-group alignment


--
Regards,
Amit Arora