fsck option --lost-and-found

fsck option --lost-and-found

[Joachim Wagner]

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Hi!

The attached patch extends reiserfsck to read the name of the lost+found 
directory from the command line option --lost-and-found. I regard it as a 
"trivial improvement" for the purpose of licencing as described in the 
reiserfsprogs README.

Motivation: Due to some problems with my external USB drive, I had to run 
reiserfsck --rebuild-tree -S. Unfortunately, I deleted the directory 
"lost+found" a while ago and reiserfsck 3.6.18 aborted in line 348 of 
lost+found.c. Afterwards, it wasn't possible to mount the fs in order to 
create the directory. I downloaded the 3.6.19 source, replaced all 
occurrences of the constant string "lost+found" with an existing directory 
and then could finish the filesystem check (recovering many files).

The patched version passed the attached test script.

I also ran the same test with an additional dd if=/dev/urandom bs=1024k 
count=320 >> /temp.img between the other two dd commands. The immediate mount 
produced an error message, but reiserfsck still worked fine. However, running 
it a second time with a different lost+found directory name (home), I got 
many new errors in pass0 (mostly wrong order of items), all numbered files 
from /etc (lost+found of 1st run) disappeared and many numbered files 
appeared in /home. Running it a 2nd time, there are still some errors. Does 
this mean
 * that there is a fundamental problem with changing the
    lost+found directory name or
 * that a successfull reiserfsck run does not guarantee a
    consistent filesystem or
 * is this just an artifact of the -S option?

Happy New Year!
Joachim

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diff -U 3 -r reiserfsprogs-3.6.19-orig/fsck/fsck.h reiserfsprogs-3.6.19/fsck/fsck.h
--- reiserfsprogs-3.6.19-orig/fsck/fsck.h	2004-10-01 14:03:43.000000000 +0200
+++ reiserfsprogs-3.6.19/fsck/fsck.h	2006-12-27 12:41:32.000000000 +0100
@@ -406,6 +406,7 @@
     struct check_info check;
 
     char * journal_dev_name; 
+    char * lost_found_name;
     /* log file name and handle */
     char * log_file_name;
     FILE * log;
diff -U 3 -r reiserfsprogs-3.6.19-orig/fsck/lost+found.c reiserfsprogs-3.6.19/fsck/lost+found.c
--- reiserfsprogs-3.6.19-orig/fsck/lost+found.c	2004-09-16 09:17:27.000000000 +0200
+++ reiserfsprogs-3.6.19/fsck/lost+found.c	2006-12-27 12:39:24.000000000 +0100
@@ -341,16 +341,17 @@
 
     /* update /lost+found sd_size and sd_blocks (nlink is correct already) */
 
-    objectid = reiserfs_find_entry (fs, &root_dir_key, "lost+found",
+    objectid = reiserfs_find_entry (fs, &root_dir_key, fsck_data(fs)->lost_found_name,
                                        &gen_counter, &lost_found_dir_key);
 
     if (!objectid) {
-       reiserfs_panic ("look_for_lost: The entry 'lost+found' could not be found in the root directory.");
+       reiserfs_panic ("look_for_lost: The entry '%s' could not be found in the root directory.",
+			fsck_data(fs)->lost_found_name);
     }
 
     if (reiserfs_search_by_key_4 (fs, &lost_found_dir_key, &path) != ITEM_FOUND)
-	reiserfs_panic ("look_for_lost: The StatData of the 'lost+found' directory %K could not be found",
-			&lost_found_dir_key);
+	reiserfs_panic ("look_for_lost: The StatData of the '%s' directory %K could not be found",
+			fsck_data(fs)->lost_found_name, &lost_found_dir_key);
     ih = get_ih (&path);
     sd = get_item (&path);
     get_sd_size (ih, sd, &sd_size);
diff -U 3 -r reiserfsprogs-3.6.19-orig/fsck/main.c reiserfsprogs-3.6.19/fsck/main.c
--- reiserfsprogs-3.6.19-orig/fsck/main.c	2004-10-07 16:04:08.000000000 +0200
+++ reiserfsprogs-3.6.19/fsck/main.c	2006-12-27 13:54:13.000000000 +0100
@@ -16,6 +16,8 @@
 reiserfs_filsys_t * fs;
 char * badblocks_file;
 
+#define LOST_FOUND_DEFAULT "lost+found"
+
 #define print_usage_and_exit() {						\
 fsck_progress ("Usage: %s [mode] [options] "					\
 " device\n"									\
@@ -42,6 +44,7 @@
 "  -f and -r\t\t\tignored\n"							\
 "Expert options:\n"								\
 "  --no-journal-available\tdo not open nor replay journal\n"			\
+"  -L | --lost-and-found directory\tname of the " LOST_FOUND_DEFAULT " directory\n"	\
 "  -S | --scan-whole-partition\tbuild tree of all blocks of the device\n\n",	\
   argv[0]);									\
 										\
@@ -99,6 +102,7 @@
 	    /* options */
 	    {"logfile", required_argument, 0, 'l'},
 	    {"badblocks", required_argument, 0, 'B'},
+	    {"lost-and-found", required_argument, 0, 'L'},
 	    {"interactive", no_argument, 0, 'i'},
 	    {"adjust-size", no_argument, 0, 'z'},
 	    {"quiet", no_argument, 0, 'q'},
@@ -131,7 +135,7 @@
 	};
 	int option_index;
       
-	c = getopt_long (argc, argv, "iql:nb:Szd:R:h:j:gafVrpyt:B:",
+	c = getopt_long (argc, argv, "iql:nb:Szd:R:h:j:gafVrpyt:B:L:",
 			 options, &option_index);
 	if (c == -1)
 	    break;
@@ -167,6 +171,10 @@
 		    optarg, strerror(errno));	    
 	    break;
 
+	case 'L': /* name of lost+found directory */
+	    asprintf (&data->lost_found_name, "%s", optarg);
+	    break;
+
 	case 'n': /* --nolog */
 	    data->options |= OPT_SILENT;
 	    break;
@@ -1217,6 +1225,7 @@
     }
 
     data = getmem (sizeof (struct fsck_data));
+    data->lost_found_name = LOST_FOUND_DEFAULT;
 
     file_name = parse_options (data, argc, argv);
 
diff -U 3 -r reiserfsprogs-3.6.19-orig/fsck/reiserfsck.8 reiserfsprogs-3.6.19/fsck/reiserfsck.8
--- reiserfsprogs-3.6.19-orig/fsck/reiserfsck.8	2004-10-13 14:53:30.000000000 +0200
+++ reiserfsprogs-3.6.19/fsck/reiserfsck.8	2006-12-27 14:10:05.000000000 +0100
@@ -15,6 +15,7 @@
 [ \fB-n\fR | \fB--nolog\fR ]
 [ \fB-B\fR | \fB--badblocks \fIfile\fR ]
 [ \fB-l\fR | \fB--logfile \fIfile\fR ]
+[ \fB-L\fR | \fB--lost-and-found \fIdirectory-name\fR ]
 [ \fB-q\fR | \fB--quiet\fR ]
 [ \fB-y\fR | \fB--yes\fR ]
 .\" [ \fB-b\fR | \fB--scan-marked-in-bitmap \fIbitmap-filename\fR ]
@@ -101,6 +102,14 @@
 This option causes \fBreiserfsck\fR to report any corruption it finds 
 to the specified log file rather than to stderr.
 .TP
+\fB--lost-and-found \fIdirectory-name\fR, \fB-L \fI directory-name\fR
+This option sets the name of the directory to store lost and found
+items (files, directories, etc.). Default is 'lost+found'. 
+Normally, \fBreiserfsck\fR will create the directory if it does not
+exist.
+If it fails, you may have luck with a different (existing) top-level
+directory, for example a login name in case of a /home filesystem.
+.TP
 .B --nolog, -n
 This option prevents \fBreiserfsck\fR from reporting any kinds of corruption.
 .TP
diff -U 3 -r reiserfsprogs-3.6.19-orig/fsck/semantic_rebuild.c reiserfsprogs-3.6.19/fsck/semantic_rebuild.c
--- reiserfsprogs-3.6.19-orig/fsck/semantic_rebuild.c	2004-09-15 15:54:22.000000000 +0200
+++ reiserfsprogs-3.6.19/fsck/semantic_rebuild.c	2006-12-27 12:48:55.000000000 +0100
@@ -1069,13 +1069,13 @@
 
     /* look for "lost+found" in the root directory */
     retval = reiserfs_find_entry (fs, &root_dir_key,
-				  "lost+found", &gen_counter,
+				  fsck_data(fs)->lost_found_name, &gen_counter,
 				  &lost_found_dir_key);
     if (!retval) {
 	objectid = id_map_alloc(proper_id_map(fs));
 	if (!objectid) {
-	    fsck_progress ("Could not allocate an objectid for \"/lost+found\", \
-		lost files will not be linked\n");
+	    fsck_progress ("Could not allocate an objectid for \"/%s\", \
+		lost files will not be linked\n", fsck_data(fs)->lost_found_name);
 	    return;
 	}
 	set_key_dirid (&lost_found_dir_key, REISERFS_ROOT_OBJECTID);
@@ -1096,8 +1096,8 @@
 	fix_obviously_wrong_sd_mode (&path);
 	
 	if (not_a_directory (get_item (&path))) {
-	    fsck_progress ("\"/lost+found\" exists, but it is not a directory, \
-		lost files will not be linked\n");
+	    fsck_progress ("\"/%s\" exists, but it is not a directory, \
+		lost files will not be linked\n", fsck_data(fs)->lost_found_name);
 	    set_key_objectid (&lost_found_dir_key, 0);
 	    pathrelse (&path);
 	    return;
@@ -1114,8 +1114,9 @@
     reiserfs_add_entry (fs, &lost_found_dir_key, "..", name_length ("..", lost_found_dir_format),
     		&root_dir_key, 1 << IH_Unreachable);
 
-    item_len = reiserfs_add_entry (fs, &root_dir_key, "lost+found",
-    		name_length ("lost+found", root_dir_format), &lost_found_dir_key, 1 << IH_Unreachable);
+    item_len = reiserfs_add_entry (fs, &root_dir_key, fsck_data(fs)->lost_found_name,
+    		name_length (fsck_data(fs)->lost_found_name, root_dir_format),
+		&lost_found_dir_key, 1 << IH_Unreachable);
 
     if (item_len) {
 	if (reiserfs_search_by_key_4 (fs, &root_dir_key, &path) == ITEM_NOT_FOUND)

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Re: fsck option --lost-and-found

[Joachim Wagner]

Hi,

> reiserfsck is supposed to create lost+found if it does not exist. 3.6.18
> has  a bug. 3.6.19 is better, but it also has problem with lost+found.
Sorry that I didn't look at the differences between 3.6.18 and 3.6.19 in the 
first place and give 3.6.19 a try. The change_log didn't say anything about 
lost+found and I assumed that one of the few things went wrong that can go 
wrong in the function make_sure_lost_found_exists. If you think that this is 
very unlikely and I only experienced a 3.6.18 bug, I understand that my patch 
will not be included.

> ftp://ftp.namesys.com/pub/tmp/reiserfsprogs-3.6.19.tar.gz fixes them.
(1) I ran diff -r with and without -w and noticed many changes in whitespace, 
mostly in struct definitions. You may want to fix this before the release of 
3.6.20.
(2) I looked at the differences of the function make_sure_lost_found_exists 
(which now moved from semantic_rebuild.c to lost+found.c)  and looked into 
reiserfs_add_entry of the 2.6.13-15.13 SuSE kernel to see what happens if 
namelen is -1. (Checking for this situation is what has been added since 
3.6.18 to make_sure_lost_found_exists.) The first thing that will cause 
problems is a call to memcpy with count -1. This will overwrite 4 GB of 
kernel memory on 32-bit i686. Shouldn't that cause a page fault or kill the 
whole system? Then the bug I experienced most have been a different one 
because this didn't happen.

> successfull reiserfsck is supposed to leave a filesystem in consistent
> state [...]
Thinking about this a little bit more, reiserfsck is neither supposed to be a 
full-blown data recovery tools (that would not write to the fs at all) nor a 
replacement for mkreiserfs + restore of a backup. Its major advantage is that 
it often brings back a system without any human interaction and at higher 
speed than the start-from-scratch option (at least if --rebuild-tree is not 
necessary).

Joachim

Re: fsck option --lost-and-found

[Joachim Wagner]

Hi Vladimir,

> Do you still reproduce the problem with 
> ftp://ftp.namesys.com/pub/tmp/reiserfsprogs-3.6.19.tar.gz?
I didn't make a copy of the partition nor a debugreiserfs image, so I cannot 
tell.

Happy New Year
Joachim