btrfs-progs: add dry-run option to restore command

Sometimes it is useful to see what btrfs restore is going to do
before provisioning enough external storage to restore onto.
Add a dry-run option so we can see what files and paths are found
by restore, without actually restoring any data.

Signed-off-by: Justin Maggard <jmaggard10@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/cmds-restore.c b/cmds-restore.c
index 1748262..fd533ce 100644 (file)
--- a/cmds-restore.c
+++ b/cmds-restore.c
@@ -53,6 +53,7 @@ static int verbose = 0;
 static int ignore_errors = 0;
 static int overwrite = 0;
 static int get_xattrs = 0;
+static int dry_run = 0;
 
 #define LZO_LEN 4
 #define PAGE_CACHE_SIZE 4096
@@ -801,6 +802,8 @@ static int search_dir(struct btrfs_root *root, struct btrfs_key *key,
                        }
                        if (verbose)
                                printf("Restoring %s\n", path_name);
+                       if (dry_run)
+                               goto next;
                        fd = open(path_name, O_CREAT|O_WRONLY, 0644);
                        if (fd < 0) {
                                fprintf(stderr, "Error creating %s: %d\n",
@@ -873,7 +876,10 @@ static int search_dir(struct btrfs_root *root, struct btrfs_key *key,
                                printf("Restoring %s\n", path_name);
 
                        errno = 0;
-                       ret = mkdir(path_name, 0755);
+                       if (dry_run)
+                               ret = 0;
+                       else
+                               ret = mkdir(path_name, 0755);
                        if (ret && errno != EEXIST) {
                                free(dir);
                                fprintf(stderr, "Error mkdiring %s: %d\n",
@@ -1090,6 +1096,7 @@ out:
 
 static struct option long_options[] = {
        { "path-regex", 1, NULL, 256},
+       { "dry-run", 0, NULL, 'D'},
        { NULL, 0, NULL, 0}
 };
 
@@ -1105,9 +1112,10 @@ const char * const cmd_restore_usage[] = {
        "-t <location>   tree location",
        "-f <offset>     filesystem location",
        "-u <block>      super mirror",
-       "-r <rootid>     root objectid",
+       "-r <rootid>     root objectid",
        "-d              find dir",
        "-l              list tree roots",
+       "-D|--dry-run    dry run (only list files that would be recovered)",
        "--path-regex <regex>",
        "                restore only filenames matching regex,",
        "                you have to use following syntax (possibly quoted):",
@@ -1135,7 +1143,7 @@ int cmd_restore(int argc, char **argv)
        regex_t match_reg, *mreg = NULL;
        char reg_err[256];
 
-       while ((opt = getopt_long(argc, argv, "sxviot:u:df:r:lc", long_options,
+       while ((opt = getopt_long(argc, argv, "sxviot:u:df:r:lDc", long_options,
                                        &option_index)) != -1) {
 
                switch (opt) {
@@ -1191,6 +1199,9 @@ int cmd_restore(int argc, char **argv)
                        case 'l':
                                list_roots = 1;
                                break;
+                       case 'D':
+                               dry_run = 1;
+                               break;
                        case 'c':
                                match_cflags |= REG_ICASE;
                                break;
@@ -1282,6 +1293,9 @@ int cmd_restore(int argc, char **argv)
                mreg = &match_reg;
        }
 
+       if (dry_run)
+               printf("This is a dry-run, no files are going to be restored\n");
+
        ret = search_dir(root, &key, dir_name, "", mreg);
 
 out: