BACKPORT: f2fs: fix to mitigate overhead of f2fs_zero_post_eof_page()

f2fs_zero_post_eof_page() may cuase more overhead due to invalidate_lock
and page lookup, change as below to mitigate its overhead:
- check new_size before grabbing invalidate_lock
- lookup and invalidate pages only in range of [old_size, new_size]

Bug: 432527227
[Chao: adjust the code]
(cherry picked from commit c2f7c32)
Change-Id: If1f91fb4a7651272e90ebc63dd9d691d5bd323fb
Fixes: ba8dac3 ("f2fs: fix to zero post-eof page")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Chao Yu <chao@kernel.org>

Author: chaseyu

fs/f2fs/file.c

@@ -38,15 +38,23 @@
 #undef CREATE_TRACE_POINTS
 #include <trace/hooks/fs.h>
 
-static void f2fs_zero_post_eof_page(struct inode *inode, loff_t new_size)
+static void f2fs_zero_post_eof_page(struct inode *inode,
+					loff_t new_size, bool lock)
 {
 	loff_t old_size = i_size_read(inode);
 
 	if (old_size >= new_size)
 		return;
 
+	if (mapping_empty(inode->i_mapping))
+		return;
+
+	if (lock)
+		filemap_invalidate_lock(inode->i_mapping);
 	/* zero or drop pages only in range of [old_size, new_size] */
-	truncate_pagecache(inode, old_size);
+	truncate_inode_pages_range(inode->i_mapping, old_size, new_size);
+	if (lock)
+		filemap_invalidate_unlock(inode->i_mapping);
 }
 
 vm_fault_t f2fs_filemap_fault(struct vm_fault *vmf)
@@ -117,9 +125,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
 
 	f2fs_bug_on(sbi, f2fs_has_inline_data(inode));
 
-	filemap_invalidate_lock(inode->i_mapping);
-	f2fs_zero_post_eof_page(inode, (folio->index + 1) << PAGE_SHIFT);
-	filemap_invalidate_unlock(inode->i_mapping);
+	f2fs_zero_post_eof_page(inode, (folio->index + 1) << PAGE_SHIFT, true);
 
 	file_update_time(vmf->vma->vm_file);
 	filemap_invalidate_lock_shared(inode->i_mapping);
@@ -1134,7 +1140,7 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		filemap_invalidate_lock(inode->i_mapping);
 
 		if (attr->ia_size > old_size)
-			f2fs_zero_post_eof_page(inode, attr->ia_size);
+			f2fs_zero_post_eof_page(inode, attr->ia_size, false);
 		truncate_setsize(inode, attr->ia_size);
 
 		if (attr->ia_size <= old_size)
@@ -1253,9 +1259,7 @@ static int f2fs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 	if (ret)
 		return ret;
 
-	filemap_invalidate_lock(inode->i_mapping);
-	f2fs_zero_post_eof_page(inode, offset + len);
-	filemap_invalidate_unlock(inode->i_mapping);
+	f2fs_zero_post_eof_page(inode, offset + len, true);
 
 	pg_start = ((unsigned long long) offset) >> PAGE_SHIFT;
 	pg_end = ((unsigned long long) offset + len) >> PAGE_SHIFT;
@@ -1540,7 +1544,7 @@ static int f2fs_do_collapse(struct inode *inode, loff_t offset, loff_t len)
 	f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
 	filemap_invalidate_lock(inode->i_mapping);
 
-	f2fs_zero_post_eof_page(inode, offset + len);
+	f2fs_zero_post_eof_page(inode, offset + len, false);
 
 	f2fs_lock_op(sbi);
 	f2fs_drop_extent_tree(inode);
@@ -1663,9 +1667,7 @@ static int f2fs_zero_range(struct inode *inode, loff_t offset, loff_t len,
 	if (ret)
 		return ret;
 
-	filemap_invalidate_lock(mapping);
-	f2fs_zero_post_eof_page(inode, offset + len);
-	filemap_invalidate_unlock(mapping);
+	f2fs_zero_post_eof_page(inode, offset + len, true);
 
 	pg_start = ((unsigned long long) offset) >> PAGE_SHIFT;
 	pg_end = ((unsigned long long) offset + len) >> PAGE_SHIFT;
@@ -1799,7 +1801,7 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len)
 	f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
 	filemap_invalidate_lock(mapping);
 
-	f2fs_zero_post_eof_page(inode, offset + len);
+	f2fs_zero_post_eof_page(inode, offset + len, false);
 	truncate_pagecache(inode, offset);
 
 	while (!ret && idx > pg_start) {
@@ -1857,9 +1859,7 @@ static int f2fs_expand_inode_data(struct inode *inode, loff_t offset,
 	if (err)
 		return err;
 
-	filemap_invalidate_lock(inode->i_mapping);
-	f2fs_zero_post_eof_page(inode, offset + len);
-	filemap_invalidate_unlock(inode->i_mapping);
+	f2fs_zero_post_eof_page(inode, offset + len, true);
 
 	f2fs_balance_fs(sbi, true);
 
@@ -4912,9 +4912,8 @@ static ssize_t f2fs_write_checks(struct kiocb *iocb, struct iov_iter *from)
 	if (err)
 		return err;
 
-	filemap_invalidate_lock(inode->i_mapping);
-	f2fs_zero_post_eof_page(inode, iocb->ki_pos + iov_iter_count(from));
-	filemap_invalidate_unlock(inode->i_mapping);
+	f2fs_zero_post_eof_page(inode,
+		iocb->ki_pos + iov_iter_count(from), true);
 	return count;
 }