[PATCH v2 00/10] hugetlbfs: add fallocate support

[Mike Kravetz]

Primary change in this revision is to fix the leak found by Hillf
Danton.  Also, changed region_del to use LONG_MAX as an indicator
of "truncate" functionality.  Considered using LLONG_MAX for same
type of indicator in remove_inode_hugepages instead of -1, but kept
-1 as LLONG_MAX could potentially be a valid offset some day.  All
changes are in the log below.

As suggested during the RFC process, tests have been proposed to
libhugetlbfs as described at:
http://librelist.com/browser//libhugetlbfs/2015/6/25/patch-tests-add-tests-for-fallocate-system-call/
fallocate(2) man page modifications are also necessary to specify
that fallocate for hugetlbfs only operates on whole pages.  This
change will be submitted once the code has stabilized and been
proposed for merging.

hugetlbfs is used today by applications that want a high degree of
control over huge page usage.  Often, large hugetlbfs files are used
to map a large number huge pages into the application processes.
The applications know when page ranges within these large files will
no longer be used, and ideally would like to release them back to
the subpool or global pools for other uses.  The fallocate() system
call provides an interface for preallocation and hole punching within
files.  This patch set adds fallocate functionality to hugetlbfs.

v2:
  Fixed leak in resv_map_release discovered by Hillf Danton.
  Used LONG_MAX as indicator of truncate function for region_del.
v1:
  Add a cache of region descriptors to the resv_map for use by
    region_add in case hole punch deletes entries necessary for
    a successful operation.
RFC v4:
  Removed alloc_huge_page/hugetlb_reserve_pages race patches as already
    in mmotm
  Moved hugetlb_fix_reserve_counts in series as suggested by Naoya Horiguchi
  Inline'ed hugetlb_fault_mutex routines as suggested by Davidlohr Bueso and
    existing code changed to use new interfaces as suggested by Naoya
  fallocate preallocation code cleaned up and made simpler
  Modified alloc_huge_page to handle special case where allocation is
    for a hole punched area with spool reserves
RFC v3:
  Folded in patch for alloc_huge_page/hugetlb_reserve_pages race
    in current code
  fallocate allocation and hole punch is synchronized with page
    faults via existing mutex table
   hole punch uses existing hugetlb_vmtruncate_list instead of more
    generic unmap_mapping_range for unmapping
   Error handling for the case when region_del() fauils
RFC v2:
  Addressed alignment and error handling issues noticed by Hillf Danton
  New region_del() routine for region tracking/resv_map of ranges
  Fixed several issues found during more extensive testing
  Error handling in region_del() when kmalloc() fails stills needs
    to be addressed
  madvise remove support remains

Mike Kravetz (10):
  mm/hugetlb: add cache of descriptors to resv_map for region_add
  mm/hugetlb: add region_del() to delete a specific range of entries
  mm/hugetlb: expose hugetlb fault mutex for use by fallocate
  hugetlbfs: hugetlb_vmtruncate_list() needs to take a range to delete
  hugetlbfs: truncate_hugepages() takes a range of pages
  mm/hugetlb: vma_has_reserves() needs to handle fallocate hole punch
  mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate
  hugetlbfs: New huge_add_to_page_cache helper routine
  hugetlbfs: add hugetlbfs_fallocate()
  mm: madvise allow remove operation for hugetlbfs

 fs/hugetlbfs/inode.c    | 281 +++++++++++++++++++++++++++++---
 include/linux/hugetlb.h |  17 +-
 mm/hugetlb.c            | 422 ++++++++++++++++++++++++++++++++++++++----------
 mm/madvise.c            |   2 +-
 4 files changed, 618 insertions(+), 104 deletions(-)

-- 
2.1.0

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