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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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