e2fsck: always submit logical block 0 of a directory for pass 2

Always iterate logical block 0 in a directory, even if no physical
block has been allocated.  Pass 2 will notice the lack of mapping and
offer to allocate a new directory block; this enables us to link the
directory into lost+found.

Previously, if there were no logical blocks mapped, we would fail to
pick up even block 0 of the directory for processing in pass 2.  This
meant that e2fsck never allocated a block 0 and therefore wouldn't fix
the missing . and .. entries for the directory; subsequent e2fsck runs
would complain about (yet never fix) the problem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

e2fsck/pass1.c

@@ -2377,6 +2377,21 @@ static int process_block(ext2_filsys fs,
 		return 0;
 	}
 
+	/*
+	 * For a directory, add logical block zero for processing even if it's
+	 * not mapped or we'll be perennially stuck with broken "." and ".."
+	 * entries.
+	 */
+	if (p->is_dir && blockcnt == 0 && blk == 0) {
+		pctx->errcode = ext2fs_add_dir_block2(fs->dblist, p->ino, 0, 0);
+		if (pctx->errcode) {
+			pctx->blk = blk;
+			pctx->num = blockcnt;
+			goto failed_add_dir_block;
+		}
+		p->last_db_block++;
+	}
+
 	if (blk == 0)
 		return 0;
 

tests/f_emptydir/expect.1

@@ -0,0 +1,19 @@
+Pass 1: Checking inodes, blocks, and sizes
+Inode 12, i_size is 1024, should be 0.  Fix? yes
+
+Pass 2: Checking directory structure
+Directory inode 12 has an unallocated block #0.  Allocate? yes
+
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+Free blocks count wrong for group #0 (957, counted=956).
+Fix? yes
+
+Free blocks count wrong (957, counted=956).
+Fix? yes
+
+
+test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
+test_filesys: 12/256 files (8.3% non-contiguous), 1092/2048 blocks
+Exit status is 1

tests/f_emptydir/expect.2

@@ -0,0 +1,7 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+test_filesys: 12/256 files (16.7% non-contiguous), 1092/2048 blocks
+Exit status is 0

tests/f_emptydir/name

@@ -0,0 +1,2 @@
+always iterate dir block 0 or e2fsck goes into infinite loop
+