fs/ntfs3: zero-fill folios beyond i_valid in ntfs_read_folio()

Handle ntfs_read_folio() early when the folio offset is beyond i_valid
by zero-filling the folio and marking it uptodate. This avoids needless
I/O and locking, improves read performance.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

Author: aalexandrovich

fs/ntfs3/inode.c

@@ -723,6 +723,19 @@ static int ntfs_read_folio(struct file *file, struct folio *folio)
 	struct address_space *mapping = folio->mapping;
 	struct inode *inode = mapping->host;
 	struct ntfs_inode *ni = ntfs_i(inode);
+	loff_t vbo = folio_pos(folio);
+
+	if (unlikely(is_bad_ni(ni))) {
+		folio_unlock(folio);
+		return -EIO;
+	}
+
+	if (ni->i_valid <= vbo) {
+		folio_zero_range(folio, 0, folio_size(folio));
+		folio_mark_uptodate(folio);
+		folio_unlock(folio);
+		return 0;
+	}
 
 	if (is_resident(ni)) {
 		ni_lock(ni);