mm/hugetlbfs: fix bugs in fallocate hole punch of areas with holes

Hugh Dickins pointed out problems with the new hugetlbfs fallocate hole
punch code.  These problems are in the routine remove_inode_hugepages and
mostly occur in the case where there are holes in the range of pages to be
removed.  These holes could be the result of a previous hole punch or
simply sparse allocation.  The current code could access pages outside the
specified range.

remove_inode_hugepages handles both hole punch and truncate operations.
Page index handling was fixed/cleaned up so that the loop index always
matches the page being processed.  The code now only makes a single pass
through the range of pages as it was determined page faults could not race
with truncate.  A cond_resched() was added after removing up to
PAGEVEC_SIZE pages.

Some totally unnecessary code in hugetlbfs_fallocate() that remained from
early development was also removed.

Tested with fallocate tests submitted here:
http://librelist.com/browser//libhugetlbfs/2015/6/25/patch-tests-add-tests-for-fallocate-system-call/
And, some ftruncate tests under development

Fixes: b5cec28d36f5 ("hugetlbfs: truncate_hugepages() takes a range of pages")
Signed-off-by: Mike Kravetz <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: "Hillf Danton" <[email protected]>
Cc: <[email protected]>	[4.3]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions