e2fsck: use root dir for lost+found when really desperate

If we're totally unable to allocate a lost+found directory, ask the
user if he would like to dump orphaned files in the root directory.
Hopefully this enables the user to delete enough files so that a
subsequent run of e2fsck will make more progress.  Better to cram lost
files in the rootdir than the current behavior, which is to fail at
linking them in, thereby leaving them as lost files.

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

e2fsck/pass3.c

@@ -450,6 +450,12 @@ unlink:
 		goto skip_new_block;
 	}
 	retval = ext2fs_new_block2(fs, 0, ctx->block_found_map, &blk);
+	if (retval == EXT2_ET_BLOCK_ALLOC_FAIL &&
+	    fix_problem(ctx, PR_3_LPF_NO_SPACE, &pctx)) {
+		printf("Delete some files and re-run e2fsck.\n\n");
+		ctx->lost_and_found = EXT2_ROOT_INO;
+		return 0;
+	}
 	if (retval) {
 		pctx.errcode = retval;
 		fix_problem(ctx, PR_3_ERR_LPF_NEW_BLOCK, &pctx);
@@ -464,6 +470,12 @@ skip_new_block:
 	 */
 	retval = ext2fs_new_inode(fs, EXT2_ROOT_INO, 040700,
 				  ctx->inode_used_map, &ino);
+	if (retval == EXT2_ET_INODE_ALLOC_FAIL &&
+	    fix_problem(ctx, PR_3_LPF_NO_SPACE, &pctx)) {
+		printf("Delete some files and re-run e2fsck.\n\n");
+		ctx->lost_and_found = EXT2_ROOT_INO;
+		return 0;
+	}
 	if (retval) {
 		pctx.errcode = retval;
 		fix_problem(ctx, PR_3_ERR_LPF_NEW_INODE, &pctx);

e2fsck/problem.c

@@ -1630,6 +1630,11 @@ static struct e2fsck_problem problem_table[] = {
 	  N_("/@l has inline data\n"),
 	  PROMPT_CLEAR, 0 },
 
+	/* Cannot allocate /lost+found. */
+	{ PR_3_LPF_NO_SPACE,
+	  N_("Cannot allocate space for /@l.\nPlace lost files in root directory instead"),
+	  PROMPT_NULL, 0 },
+
 	/* Pass 3A Directory Optimization	*/
 
 	/* Pass 3A: Optimizing directories */

e2fsck/problem.h

@@ -973,6 +973,9 @@ struct problem_context {
 /* Lost+found has inline data */
 #define PR_3_LPF_INLINE_DATA		0x030018
 
+/* Cannot allocate lost+found */
+#define PR_3_LPF_NO_SPACE		0x030019
+
 /*
  * Pass 3a --- rehashing diretories
  */

tests/f_nospc_create_lnf/expect.1

@@ -0,0 +1,28 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+/lost+found not found.  Create? yes
+
+Cannot allocate space for /lost+found.
+Place lost files in root directory instead? yes
+
+Delete some files and re-run e2fsck.
+
+Pass 3A: Optimizing directories
+Pass 4: Checking reference counts
+Unattached inode 125
+Connect to /lost+found? yes
+
+Inode 125 ref count is 2, should be 1.  Fix? yes
+
+Pass 5: Checking group summary information
+Free blocks count wrong for group #0 (496, counted=495).
+Fix? yes
+
+Free blocks count wrong (496, counted=495).
+Fix? yes
+
+
+test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
+test_filesys: 128/128 files (0.0% non-contiguous), 17/512 blocks
+Exit status is 1

tests/f_nospc_create_lnf/expect.2

@@ -0,0 +1,25 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+/lost+found not found.  Create? yes
+
+Cannot allocate space for /lost+found.
+Place lost files in root directory instead? yes
+
+Delete some files and re-run e2fsck.
+
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+Block bitmap differences:  -9
+Fix? yes
+
+Free blocks count wrong for group #0 (494, counted=495).
+Fix? yes
+
+Free blocks count wrong (494, counted=495).
+Fix? yes
+
+
+test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
+test_filesys: 128/128 files (0.0% non-contiguous), 17/512 blocks
+Exit status is 1

tests/f_nospc_create_lnf/name

@@ -0,0 +1 @@
+no space to create lost+found