1 files changed, 46 insertions, 72 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index a7f6b31..3acf353 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3693,6 +3693,41 @@ unlock:
 	return err;
 }
 
+int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
+			     loff_t lstart, loff_t length)
+{
+	struct super_block *sb = inode->i_sb;
+	struct address_space *mapping = inode->i_mapping;
+	unsigned partial = lstart & (sb->s_blocksize - 1);
+	ext4_fsblk_t start, end;
+	loff_t byte_end = (lstart + length - 1);
+	int err = 0;
+
+	start = lstart >> sb->s_blocksize_bits;
+	end = byte_end >> sb->s_blocksize_bits;
+
+	/* Handle partial zero within the single block */
+	if (start == end) {
+		err = ext4_block_zero_page_range(handle, mapping,
+						 lstart, length);
+		return err;
+	}
+	/* Handle partial zero out on the start of the range */
+	if (partial) {
+		err = ext4_block_zero_page_range(handle, mapping,
+						 lstart, sb->s_blocksize);
+		if (err)
+			return err;
+	}
+	/* Handle partial zero out on the end of the range */
+	partial = byte_end & (sb->s_blocksize - 1);
+	if (partial != sb->s_blocksize - 1)
+		err = ext4_block_zero_page_range(handle, mapping,
+						 byte_end - partial,
+						 partial + 1);
+	return err;
+}
+
 int ext4_can_truncate(struct inode *inode)
 {
 	if (S_ISREG(inode->i_mode))
@@ -3721,8 +3756,7 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 	struct super_block *sb = inode->i_sb;
 	ext4_lblk_t first_block, stop_block;
 	struct address_space *mapping = inode->i_mapping;
-	loff_t first_page, last_page, page_len;
-	loff_t first_page_offset, last_page_offset;
+	loff_t first_block_offset, last_block_offset;
 	handle_t *handle;
 	unsigned int credits;
 	int ret = 0;
@@ -3773,17 +3807,13 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 		   offset;
 	}
 
-	first_page = (offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-	last_page = (offset + length) >> PAGE_CACHE_SHIFT;
+	first_block_offset = round_up(offset, sb->s_blocksize);
+	last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
 
-	first_page_offset = first_page << PAGE_CACHE_SHIFT;
-	last_page_offset = last_page << PAGE_CACHE_SHIFT;
-
-	/* Now release the pages */
-	if (last_page_offset > first_page_offset) {
-		truncate_pagecache_range(inode, first_page_offset,
-					 last_page_offset - 1);
-	}
+	/* Now release the pages and zero block aligned part of pages*/
+	if (last_block_offset > first_block_offset)
+		truncate_pagecache_range(inode, first_block_offset,
+					 last_block_offset);
 
 	/* Wait all existing dio workers, newcomers will block on i_mutex */
 	ext4_inode_block_unlocked_dio(inode);
@@ -3803,66 +3833,10 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 		goto out_dio;
 	}
 
-	/*
-	 * Now we need to zero out the non-page-aligned data in the
-	 * pages at the start and tail of the hole, and unmap the
-	 * buffer heads for the block aligned regions of the page that
-	 * were completely zeroed.
-	 */
-	if (first_page > last_page) {
-		/*
-		 * If the file space being truncated is contained
-		 * within a page just zero out and unmap the middle of
-		 * that page
-		 */
-		ret = ext4_discard_partial_page_buffers(handle,
-			mapping, offset, length, 0);
-
-		if (ret)
-			goto out_stop;
-	} else {
-		/*
-		 * zero out and unmap the partial page that contains
-		 * the start of the hole
-		 */
-		page_len = first_page_offset - offset;
-		if (page_len > 0) {
-			ret = ext4_discard_partial_page_buffers(handle, mapping,
-						offset, page_len, 0);
-			if (ret)
-				goto out_stop;
-		}
-
-		/*
-		 * zero out and unmap the partial page that contains
-		 * the end of the hole
-		 */
-		page_len = offset + length - last_page_offset;
-		if (page_len > 0) {
-			ret = ext4_discard_partial_page_buffers(handle, mapping,
-					last_page_offset, page_len, 0);
-			if (ret)
-				goto out_stop;
-		}
-	}
-
-	/*
-	 * If i_size is contained in the last page, we need to
-	 * unmap and zero the partial page after i_size
-	 */
-	if (inode->i_size >> PAGE_CACHE_SHIFT == last_page &&
-	   inode->i_size % PAGE_CACHE_SIZE != 0) {
-		page_len = PAGE_CACHE_SIZE -
-			(inode->i_size & (PAGE_CACHE_SIZE - 1));
-
-		if (page_len > 0) {
-			ret = ext4_discard_partial_page_buffers(handle,
-					mapping, inode->i_size, page_len, 0);
-
-			if (ret)
-				goto out_stop;
-		}
-	}
+	ret = ext4_zero_partial_blocks(handle, inode, offset,
+				       length);
+	if (ret)
+		goto out_stop;
 
 	first_block = (offset + sb->s_blocksize - 1) >>
 		EXT4_BLOCK_SIZE_BITS(sb);