[PATCH v2 05/10] ext4: refactor ext4_punch_hole()

[Zhang Yi <yi.zhang@huaweicloud.com>]

From: Zhang Yi <yi.zhang@huawei.com>

Current ext4_punch_hole() is full of complex position calculation and
stale error out tags. In order to clean up the code and make things
clear, refactor it by a) simplify and rename variables, make the style
the same as ext4_zero_range(), b) remove some unnecessary position
calculations, always write back dirty data and drop cache from offset to
end, instead of only write back aligned blocks, c) rename the three
stale error tags.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/ext4/inode.c | 114 ++++++++++++++++++++++--------------------------
 1 file changed, 51 insertions(+), 63 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9343ce9f2b01..dfaf9e9d6ad8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3916,13 +3916,14 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 {
 	struct inode *inode = file_inode(file);
 	struct super_block *sb = inode->i_sb;
-	ext4_lblk_t first_block, stop_block;
+	ext4_lblk_t start_lblk, end_lblk;
 	struct address_space *mapping = inode->i_mapping;
-	loff_t first_block_offset, last_block_offset, max_length;
-	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	loff_t max_end = EXT4_SB(sb)->s_bitmap_maxbytes - sb->s_blocksize;
+	loff_t end = offset + length;
+	unsigned long blocksize = i_blocksize(inode);
 	handle_t *handle;
 	unsigned int credits;
-	int ret = 0, ret2 = 0;
+	int ret = 0;
 
 	trace_ext4_punch_hole(inode, offset, length, 0);
 
@@ -3930,36 +3931,27 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 
 	/* No need to punch hole beyond i_size */
 	if (offset >= inode->i_size)
-		goto out_mutex;
+		goto out;
 
 	/*
-	 * If the hole extends beyond i_size, set the hole
-	 * to end after the page that contains i_size
+	 * If the hole extends beyond i_size, set the hole to end after
+	 * the page that contains i_size, and also make sure that the hole
+	 * within one block before last range.
 	 */
-	if (offset + length > inode->i_size) {
-		length = inode->i_size +
-		   PAGE_SIZE - (inode->i_size & (PAGE_SIZE - 1)) -
-		   offset;
-	}
+	if (end > inode->i_size)
+		end = round_up(inode->i_size, PAGE_SIZE);
+	if (end > max_end)
+		end = max_end;
+	length = end - offset;
 
 	/*
-	 * For punch hole the length + offset needs to be within one block
-	 * before last range. Adjust the length if it goes beyond that limit.
+	 * Attach jinode to inode for jbd2 if we do any zeroing of partial
+	 * block.
 	 */
-	max_length = sbi->s_bitmap_maxbytes - inode->i_sb->s_blocksize;
-	if (offset + length > max_length)
-		length = max_length - offset;
-
-	if (offset & (sb->s_blocksize - 1) ||
-	    (offset + length) & (sb->s_blocksize - 1)) {
-		/*
-		 * Attach jinode to inode for jbd2 if we do any zeroing of
-		 * partial block
-		 */
+	if (offset & (blocksize - 1) || end & (blocksize - 1)) {
 		ret = ext4_inode_attach_jinode(inode);
 		if (ret < 0)
-			goto out_mutex;
-
+			goto out;
 	}
 
 	/* Wait all existing dio workers, newcomers will block on i_rwsem */
@@ -3967,7 +3959,7 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 
 	ret = file_modified(file);
 	if (ret)
-		goto out_mutex;
+		goto out;
 
 	/*
 	 * Prevent page faults from reinstantiating pages we have released from
@@ -3977,23 +3969,17 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 
 	ret = ext4_break_layouts(inode);
 	if (ret)
-		goto out_dio;
+		goto out_invalidate_lock;
 
 	/* Write out all dirty pages to avoid race conditions */
 	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
-		ret = filemap_write_and_wait_range(mapping, offset,
-						   offset + length - 1);
+		ret = filemap_write_and_wait_range(mapping, offset, end - 1);
 		if (ret)
-			goto out_dio;
+			goto out_invalidate_lock;
 	}
 
-	first_block_offset = round_up(offset, sb->s_blocksize);
-	last_block_offset = round_down((offset + length), sb->s_blocksize) - 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);
+	truncate_pagecache_range(inode, offset, end - 1);
 
 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
 		credits = ext4_writepage_trans_blocks(inode);
@@ -4003,52 +3989,54 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 	if (IS_ERR(handle)) {
 		ret = PTR_ERR(handle);
 		ext4_std_error(sb, ret);
-		goto out_dio;
+		goto out_invalidate_lock;
 	}
 
-	ret = ext4_zero_partial_blocks(handle, inode, offset,
-				       length);
+	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);
-	stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
+		goto out_handle;
 
 	/* If there are blocks to remove, do it */
-	if (stop_block > first_block) {
-		ext4_lblk_t hole_len = stop_block - first_block;
+	start_lblk = round_up(offset, blocksize) >> inode->i_blkbits;
+	end_lblk = end >> inode->i_blkbits;
+
+	if (end_lblk > start_lblk) {
+		ext4_lblk_t hole_len = end_lblk - start_lblk;
 
 		down_write(&EXT4_I(inode)->i_data_sem);
 		ext4_discard_preallocations(inode);
 
-		ext4_es_remove_extent(inode, first_block, hole_len);
+		ext4_es_remove_extent(inode, start_lblk, hole_len);
 
 		if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
-			ret = ext4_ext_remove_space(inode, first_block,
-						    stop_block - 1);
+			ret = ext4_ext_remove_space(inode, start_lblk,
+						    end_lblk - 1);
 		else
-			ret = ext4_ind_remove_space(handle, inode, first_block,
-						    stop_block);
+			ret = ext4_ind_remove_space(handle, inode, start_lblk,
+						    end_lblk);
+		if (ret) {
+			up_write(&EXT4_I(inode)->i_data_sem);
+			goto out_handle;
+		}
 
-		ext4_es_insert_extent(inode, first_block, hole_len, ~0,
+		ext4_es_insert_extent(inode, start_lblk, hole_len, ~0,
 				      EXTENT_STATUS_HOLE);
 		up_write(&EXT4_I(inode)->i_data_sem);
 	}
-	ext4_fc_track_range(handle, inode, first_block, stop_block);
+	ext4_fc_track_range(handle, inode, start_lblk, end_lblk);
+
+	ret = ext4_mark_inode_dirty(handle, inode);
+	if (unlikely(ret))
+		goto out_handle;
+
+	ext4_update_inode_fsync_trans(handle, inode, 1);
 	if (IS_SYNC(inode))
 		ext4_handle_sync(handle);
-
-	ret2 = ext4_mark_inode_dirty(handle, inode);
-	if (unlikely(ret2))
-		ret = ret2;
-	if (ret >= 0)
-		ext4_update_inode_fsync_trans(handle, inode, 1);
-out_stop:
+out_handle:
 	ext4_journal_stop(handle);
-out_dio:
+out_invalidate_lock:
 	filemap_invalidate_unlock(mapping);
-out_mutex:
+out:
 	inode_unlock(inode);
 	return ret;
 }
-- 
2.39.2