[PATCHv3 38/41] ext4: fix SEEK_DATA/SEEK_HOLE for huge pages

Kirill A. Shutemov
2016-09-15T11:55:20Z

ext4_find_unwritten_pgoff() needs few tweaks to work with huge pages.
Mostly trivial page_mapping()/page_to_pgoff() and adjustment to how we
find relevant block.

Signe-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
fs/ext4/file.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 261ac3734c58..2c3d6bb0edfe 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -473,7 +473,7 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
* range, it will be a hole.
*/
if (lastoff < endoff && whence == SEEK_HOLE &&
- page->index > end) {
+ page_to_pgoff(page) > end) {
found = 1;
*offset = lastoff;
goto out;
@@ -481,7 +481,7 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,

lock_page(page);

- if (unlikely(page->mapping != inode->i_mapping)) {
+ if (unlikely(page_mapping(page) != inode->i_mapping)) {
unlock_page(page);
continue;
}
@@ -492,8 +492,12 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
}

if (page_has_buffers(page)) {
+ int diff;
lastoff = page_offset(page);
bh = head = page_buffers(page);
+ diff = (page - compound_head(page)) << inode->i_blkbits;
+ while (diff--)
+ bh = bh->b_this_page;
do {
if (buffer_uptodate(bh) ||
buffer_unwritten(bh)) {
@@ -514,8 +518,12 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
} while (bh != head);
}

- lastoff = page_offset(page) + PAGE_SIZE;
+ lastoff = page_offset(page) + hpage_size(page);
unlock_page(page);
+ if (PageTransCompound(page)) {
+ i++;
+ break;
+ }
}

/*
@@ -528,7 +536,9 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
break;
}

- index = pvec.pages[i - 1]->index + 1;
+ index = page_to_pgoff(pvec.pages[i - 1]) + 1;
+ if (PageTransCompound(pvec.pages[i - 1]))
+ index = round_up(index, HPAGE_PMD_NR);
pagevec_release(&pvec);
} while (index <= end);