e2fsck: optionally create an undo file

Provide the user with an option to create an undo file so that they
can roll back a failed repair operation.

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

diff --git a/e2fsck/e2fsck.8.in b/e2fsck/e2fsck.8.in
index e1bbd27..f6d8436 100644 (file)
--- a/e2fsck/e2fsck.8.in
+++ b/e2fsck/e2fsck.8.in
@@ -339,6 +339,16 @@ may not be specified at the same time as the
 or
 .B \-p
 options.
+.TP
+.BI \-z " undo_file"
+Before overwriting a file system block, write the old contents of the block to
+an undo file.  This undo file can be used with e2undo(8) to restore the old
+contents of the file system should something go wrong.  If the empty string is
+passed as the undo_file argument, the undo file will be written to a file named
+e2fsck-\fIdevice\fR.e2undo in the directory specified via the
+\fIE2FSPROGS_UNDO_DIR\fR environment variable.
+
+WARNING: The undo file cannot be used to recover from a power or system crash.
 .SH EXIT CODE
 The exit code returned by
 .B e2fsck

diff --git a/e2fsck/e2fsck.h b/e2fsck/e2fsck.h
index 8e0e302..97c6bf9 100644 (file)
--- a/e2fsck/e2fsck.h
+++ b/e2fsck/e2fsck.h
@@ -390,6 +390,9 @@ struct e2fsck_struct {
         * Inodes to rebuild extent trees
         */
        ext2fs_inode_bitmap inodes_to_rebuild;
+
+       /* Undo file */
+       char *undo_file;
 };
 
 /* Data structures to evaluate whether an extent tree needs rebuilding. */

diff --git a/e2fsck/unix.c b/e2fsck/unix.c
index 5bc829a..4bad553 100644 (file)
--- a/e2fsck/unix.c
+++ b/e2fsck/unix.c
@@ -45,6 +45,7 @@ extern int optind;
 #ifdef HAVE_DIRENT_H
 #include <dirent.h>
 #endif
+#include <libgen.h>
 
 #include "e2p/e2p.h"
 #include "et/com_err.h"
@@ -75,7 +76,7 @@ static void usage(e2fsck_t ctx)
                _("Usage: %s [-panyrcdfvtDFV] [-b superblock] [-B blocksize]\n"
                "\t\t[-I inode_buffer_blocks] [-P process_inode_size]\n"
                "\t\t[-l|-L bad_blocks_file] [-C fd] [-j external_journal]\n"
-               "\t\t[-E extended-options] device\n"),
+               "\t\t[-E extended-options] [-z undo_file] device\n"),
                ctx->program_name);
 
        fprintf(stderr, "%s", _("\nEmergency help:\n"
@@ -91,6 +92,7 @@ static void usage(e2fsck_t ctx)
                " -j external_journal  Set location of the external journal\n"
                " -l bad_blocks_file   Add to badblocks list\n"
                " -L bad_blocks_file   Set badblocks list\n"
+               " -z undo_file         Create an undo file\n"
                ));
 
        exit(FSCK_USAGE);
@@ -798,7 +800,7 @@ static errcode_t PRS(int argc, char *argv[], e2fsck_t *ret_ctx)
 
        phys_mem_kb = get_memory_size() / 1024;
        ctx->readahead_kb = ~0ULL;
-       while ((c = getopt (argc, argv, "panyrcC:B:dE:fvtFVM:b:I:j:P:l:L:N:SsDk")) != EOF)
+       while ((c = getopt(argc, argv, "panyrcC:B:dE:fvtFVM:b:I:j:P:l:L:N:SsDkz:")) != EOF)
                switch (c) {
                case 'C':
                        ctx->progress = e2fsck_update_progress;
@@ -930,6 +932,9 @@ static errcode_t PRS(int argc, char *argv[], e2fsck_t *ret_ctx)
                case 'k':
                        keep_bad_blocks++;
                        break;
+               case 'z':
+                       ctx->undo_file = optarg;
+                       break;
                default:
                        usage(ctx);
                }
@@ -1224,6 +1229,87 @@ check_error:
        return retval;
 }
 
+static int e2fsck_setup_tdb(e2fsck_t ctx, io_manager *io_ptr)
+{
+       errcode_t retval = ENOMEM;
+       char *tdb_dir = NULL, *tdb_file = NULL;
+       char *dev_name, *tmp_name;
+       int free_tdb_dir = 0;
+
+       /* (re)open a specific undo file */
+       if (ctx->undo_file && ctx->undo_file[0] != 0) {
+               set_undo_io_backing_manager(*io_ptr);
+               *io_ptr = undo_io_manager;
+               retval = set_undo_io_backup_file(ctx->undo_file);
+               if (retval)
+                       goto err;
+               printf(_("Overwriting existing filesystem; this can be undone "
+                        "using the command:\n"
+                        "    e2undo %s %s\n\n"),
+                       ctx->undo_file, ctx->filesystem_name);
+               return 0;
+       }
+
+       /*
+        * Configuration via a conf file would be
+        * nice
+        */
+       tdb_dir = getenv("E2FSPROGS_UNDO_DIR");
+       if (!tdb_dir) {
+               profile_get_string(ctx->profile, "defaults",
+                                  "undo_dir", 0, "/var/lib/e2fsprogs",
+                                  &tdb_dir);
+               free_tdb_dir = 1;
+       }
+
+       if (!strcmp(tdb_dir, "none") || (tdb_dir[0] == 0) ||
+           access(tdb_dir, W_OK)) {
+               if (free_tdb_dir)
+                       free(tdb_dir);
+               return 0;
+       }
+
+       tmp_name = strdup(ctx->filesystem_name);
+       if (!tmp_name)
+               goto errout;
+       dev_name = basename(tmp_name);
+       tdb_file = malloc(strlen(tdb_dir) + 8 + strlen(dev_name) + 7 + 1);
+       if (!tdb_file) {
+               free(tmp_name);
+               goto errout;
+       }
+       sprintf(tdb_file, "%s/e2fsck-%s.e2undo", tdb_dir, dev_name);
+       free(tmp_name);
+
+       if ((unlink(tdb_file) < 0) && (errno != ENOENT)) {
+               retval = errno;
+               goto errout;
+       }
+
+       set_undo_io_backing_manager(*io_ptr);
+       *io_ptr = undo_io_manager;
+       retval = set_undo_io_backup_file(tdb_file);
+       if (retval)
+               goto errout;
+       printf(_("Overwriting existing filesystem; this can be undone "
+                "using the command:\n"
+                "    e2undo %s %s\n\n"), tdb_file, ctx->filesystem_name);
+
+       if (free_tdb_dir)
+               free(tdb_dir);
+       free(tdb_file);
+       return 0;
+
+errout:
+       if (free_tdb_dir)
+               free(tdb_dir);
+       free(tdb_file);
+err:
+       com_err(ctx->program_name, retval, "%s",
+               _("while trying to setup undo file\n"));
+       return retval;
+}
+
 int main (int argc, char *argv[])
 {
        errcode_t       retval = 0, retval2 = 0, orig_retval = 0;
@@ -1333,6 +1419,12 @@ restart:
                        flags &= ~EXT2_FLAG_EXCLUSIVE;
        }
 
+       if (ctx->undo_file) {
+               retval = e2fsck_setup_tdb(ctx, &io_ptr);
+               if (retval)
+                       exit(FSCK_ERROR);
+       }
+
        ctx->openfs_flags = flags;
        retval = try_open_fs(ctx, flags, io_ptr, &fs);
 

diff --git a/lib/ext2fs/undo_io.c b/lib/ext2fs/undo_io.c
index df26e3e..4a48193 100644 (file)
--- a/lib/ext2fs/undo_io.c
+++ b/lib/ext2fs/undo_io.c
@@ -790,6 +790,7 @@ static errcode_t undo_close(io_channel channel)
        if (!getenv("UNDO_IO_SIMULATE_UNFINISHED"))
                data->hdr.state = ext2fs_cpu_to_le32(E2UNDO_STATE_FINISHED);
        err = write_undo_indexes(data);
+       ext2fs_remove_exit_fn(undo_atexit, data);
        if (data->real)
                retval = io_channel_close(data->real);
        if (data->tdb_file)
@@ -799,7 +800,6 @@ static errcode_t undo_close(io_channel channel)
        ext2fs_free_mem(&data->keyb);
        if (data->written_block_map)
                ext2fs_free_generic_bitmap(data->written_block_map);
-       ext2fs_remove_exit_fn(undo_atexit, data);
        ext2fs_free_mem(&channel->private_data);
        if (channel->name)
                ext2fs_free_mem(&channel->name);