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Subject[RFC PATCH 1/4] hugetlbfs: truncate_hugepages() takes a range of pages
Date
Modify truncate_hugepages() to take a range of pages (start, end)
instead of simply start. If the value of end is -1, this indicates
the end of the range is the end of the file. This functionality
will be used for fallocate hole punching.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
fs/hugetlbfs/inode.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index c274aca..d5b67fd 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -324,11 +324,12 @@ static void truncate_huge_page(struct page *page)
delete_from_page_cache(page);
}

-static void truncate_hugepages(struct inode *inode, loff_t lstart)
+static void truncate_hugepages(struct inode *inode, loff_t lstart, loff_t lend)
{
struct hstate *h = hstate_inode(inode);
struct address_space *mapping = &inode->i_data;
const pgoff_t start = lstart >> huge_page_shift(h);
+ const pgoff_t end = lend >> huge_page_shift(h);
struct pagevec pvec;
pgoff_t next;
int i, freed = 0;
@@ -336,7 +337,19 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart)
pagevec_init(&pvec, 0);
next = start;
while (1) {
- if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+ long lookup_nr = PAGEVEC_SIZE;
+
+ /*
+ * Make sure to never grab more pages that we
+ * might possibly need.
+ */
+ if (end - start < lookup_nr)
+ lookup_nr = end - start;
+ /*
+ * This pagevec_lookup() may return pages past 'end',
+ * so we must check for page->index > end.
+ */
+ if (!pagevec_lookup(&pvec, mapping, next, lookup_nr)) {
if (next == start)
break;
next = start;
@@ -347,6 +360,10 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart)
struct page *page = pvec.pages[i];

lock_page(page);
+ if (page->index >= end) {
+ unlock_page(page);
+ break;
+ }
if (page->index > next)
next = page->index;
++next;
@@ -364,7 +381,7 @@ static void hugetlbfs_evict_inode(struct inode *inode)
{
struct resv_map *resv_map;

- truncate_hugepages(inode, 0);
+ truncate_hugepages(inode, 0, -1);
resv_map = (struct resv_map *)inode->i_mapping->private_data;
/* root inode doesn't have the resv_map, so we should check it */
if (resv_map)
@@ -410,7 +427,7 @@ static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
if (!RB_EMPTY_ROOT(&mapping->i_mmap))
hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
i_mmap_unlock_write(mapping);
- truncate_hugepages(inode, offset);
+ truncate_hugepages(inode, offset, -1);
return 0;
}

--
2.1.0


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