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Subject[PATCH 07/12] mm, thp, tmpfs: handle huge page in shmem_undo_range for truncate
When comes to truncate file, add support to handle huge page in the
truncate range.

Signed-off-by: Ning Qu <quning@gmail.com>
---
mm/shmem.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 86 insertions(+), 11 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 0a423a9..90f2e0e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -559,6 +559,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
struct shmem_inode_info *info = SHMEM_I(inode);
pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
+ /* Whether we have to do partial truncate */
unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
struct pagevec pvec;
@@ -570,12 +571,16 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
if (lend == -1)
end = -1; /* unsigned, so actually very big */

+ i_split_down_read(inode);
pagevec_init(&pvec, 0);
index = start;
while (index < end) {
+ bool thp = false;
+
pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE),
pvec.pages, indices);
+
if (!pvec.nr)
break;
mem_cgroup_uncharge_start();
@@ -586,6 +591,25 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
if (index >= end)
break;

+ thp = PageTransHugeCache(page);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE
+ if (thp) {
+ /* the range starts in middle of huge page */
+ if (index < start) {
+ partial_start = true;
+ start = index + HPAGE_CACHE_NR;
+ break;
+ }
+
+ /* the range ends on huge page */
+ if (index == (end & ~HPAGE_CACHE_INDEX_MASK)) {
+ partial_end = true;
+ end = index;
+ break;
+ }
+ }
+#endif
+
if (radix_tree_exceptional_entry(page)) {
if (unfalloc)
continue;
@@ -603,26 +627,52 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
}
}
unlock_page(page);
+ if (thp)
+ break;
}
shmem_deswap_pagevec(&pvec);
pagevec_release(&pvec);
mem_cgroup_uncharge_end();
cond_resched();
- index++;
+ if (thp)
+ index += HPAGE_CACHE_NR;
+ else
+ index++;
}

if (partial_start) {
struct page *page = NULL;
gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
+ int flags = 0;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE
+ flags |= AOP_FLAG_TRANSHUGE;
+#endif

- shmem_getpage(inode, start - 1, &page, SGP_READ, gfp, 0, NULL);
+ shmem_getpage(inode, start - 1, &page, SGP_READ, gfp,
+ flags, NULL);
if (page) {
- unsigned int top = PAGE_CACHE_SIZE;
- if (start > end) {
- top = partial_end;
- partial_end = 0;
+ pgoff_t index_mask;
+ loff_t page_cache_mask;
+ unsigned pstart, pend;
+
+ index_mask = 0UL;
+ page_cache_mask = PAGE_CACHE_MASK;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE
+ if (PageTransHugeCache(page)) {
+ index_mask = HPAGE_CACHE_INDEX_MASK;
+ page_cache_mask = HPAGE_PMD_MASK;
}
- zero_user_segment(page, partial_start, top);
+#endif
+
+ pstart = lstart & ~page_cache_mask;
+ if ((end & ~index_mask) == page->index) {
+ pend = (lend + 1) & ~page_cache_mask;
+ end = page->index;
+ partial_end = false; /* handled here */
+ } else
+ pend = PAGE_CACHE_SIZE << compound_order(page);
+
+ zero_pagecache_segment(page, pstart, pend);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
@@ -631,20 +681,37 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
if (partial_end) {
struct page *page = NULL;
gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
+ int flags = 0;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE
+ flags |= AOP_FLAG_TRANSHUGE;
+#endif

- shmem_getpage(inode, end, &page, SGP_READ, gfp, 0, NULL);
+ shmem_getpage(inode, end, &page, SGP_READ, gfp,
+ flags, NULL);
if (page) {
- zero_user_segment(page, 0, partial_end);
+ loff_t page_cache_mask;
+ unsigned pend;
+
+ page_cache_mask = PAGE_CACHE_MASK;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE
+ if (PageTransHugeCache(page))
+ page_cache_mask = HPAGE_PMD_MASK;
+#endif
+ pend = (lend + 1) & ~page_cache_mask;
+ end = page->index;
+ zero_pagecache_segment(page, 0, pend);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
}
}
if (start >= end)
- return;
+ goto out;

index = start;
for ( ; ; ) {
+ bool thp = false;
+
cond_resched();
pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE),
@@ -676,6 +743,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
continue;
}

+ thp = PageTransHugeCache(page);
lock_page(page);
if (!unfalloc || !PageUptodate(page)) {
if (page->mapping == mapping) {
@@ -684,17 +752,24 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
}
}
unlock_page(page);
+ if (thp)
+ break;
}
shmem_deswap_pagevec(&pvec);
pagevec_release(&pvec);
mem_cgroup_uncharge_end();
- index++;
+ if (thp)
+ index += HPAGE_CACHE_NR;
+ else
+ index++;
}

spin_lock(&info->lock);
info->swapped -= nr_swaps_freed;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
+out:
+ i_split_up_read(inode);
}

void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
--
1.8.4



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