diff --git a/c_src/bcachefs.c b/c_src/bcachefs.c
index f488436e..aed9c261 100644
--- a/c_src/bcachefs.c
+++ b/c_src/bcachefs.c
@@ -33,6 +33,7 @@ void bcachefs_usage(void)
"Superblock commands:\n"
" format Format a new filesystem\n"
" show-super Dump superblock information to stdout\n"
+ " recover-super Attempt to recover overwritten superblock from backups\n"
" set-fs-option Set a filesystem option\n"
" reset-counters Reset all counters on an unmounted device\n"
"\n"
diff --git a/c_src/cmd_format.c b/c_src/cmd_format.c
index 730a544e..b103d2bd 100644
--- a/c_src/cmd_format.c
+++ b/c_src/cmd_format.c
@@ -433,3 +433,204 @@ int cmd_show_super(int argc, char *argv[])
printbuf_exit(&buf);
return 0;
}
+
+#include "libbcachefs/super-io.h"
+#include "libbcachefs/sb-members.h"
+
+typedef DARRAY(struct bch_sb *) probed_sb_list;
+
+static void probe_one_super(int dev_fd, unsigned sb_size, u64 offset,
+ probed_sb_list *sbs, bool verbose)
+{
+ darray_char sb_buf = {};
+ darray_resize(&sb_buf, sb_size);
+
+ xpread(dev_fd, sb_buf.data, sb_buf.size, offset);
+
+ struct printbuf err = PRINTBUF;
+ int ret = bch2_sb_validate((void *) sb_buf.data, offset >> 9, 0, &err);
+ printbuf_exit(&err);
+
+ if (!ret) {
+ if (verbose) {
+ struct printbuf buf = PRINTBUF;
+ prt_human_readable_u64(&buf, offset);
+ printf("found superblock at %s\n", buf.buf);
+ printbuf_exit(&buf);
+ }
+
+ darray_push(sbs, (void *) sb_buf.data);
+ sb_buf.data = NULL;
+ }
+
+ darray_exit(&sb_buf);
+}
+
+static void probe_sb_range(int dev_fd, u64 start_offset, u64 end_offset,
+ probed_sb_list *sbs, bool verbose)
+{
+ start_offset &= ~((u64) 511);
+ end_offset &= ~((u64) 511);
+
+ size_t buflen = end_offset - start_offset;
+ void *buf = malloc(buflen);
+ xpread(dev_fd, buf, buflen, start_offset);
+
+ for (u64 offset = 0; offset < buflen; offset += 512) {
+ struct bch_sb *sb = buf + offset;
+
+ if (!uuid_equal(&sb->magic, &BCACHE_MAGIC) &&
+ !uuid_equal(&sb->magic, &BCHFS_MAGIC))
+ continue;
+
+ size_t bytes = vstruct_bytes(sb);
+ if (offset + bytes > buflen) {
+ fprintf(stderr, "found sb %llu size %zu that overran buffer\n",
+ start_offset + offset, bytes);
+ continue;
+ }
+ struct printbuf err = PRINTBUF;
+ int ret = bch2_sb_validate(sb, (start_offset + offset) >> 9, 0, &err);
+ if (ret)
+ fprintf(stderr, "found sb %llu that failed to validate: %s\n",
+ start_offset + offset, err.buf);
+ printbuf_exit(&err);
+
+ if (ret)
+ continue;
+
+ if (verbose) {
+ struct printbuf buf = PRINTBUF;
+ prt_human_readable_u64(&buf, start_offset + offset);
+ printf("found superblock at %s\n", buf.buf);
+ printbuf_exit(&buf);
+ }
+
+ void *sb_copy = malloc(bytes);
+ memcpy(sb_copy, sb, bytes);
+ darray_push(sbs, sb_copy);
+ }
+
+ free(buf);
+}
+
+static u64 bch2_sb_last_mount_time(struct bch_sb *sb)
+{
+ u64 ret = 0;
+ for (unsigned i = 0; i < sb->nr_devices; i++)
+ ret = max(ret, le64_to_cpu(bch2_sb_member_get(sb, i).last_mount));
+ return ret;
+}
+
+static int bch2_sb_time_cmp(struct bch_sb *l, struct bch_sb *r)
+{
+ return cmp_int(bch2_sb_last_mount_time(l),
+ bch2_sb_last_mount_time(r));
+}
+
+static void recover_super_usage(void)
+{
+ puts("bcachefs recover-super \n"
+ "Usage: bcachefs recover-super [OPTION].. device\n"
+ "\n"
+ "Attempt to recover a filesystem on a device that has had the main superblock\n"
+ "and superblock layout overwritten.\n"
+ "All options will be guessed if not provided\n"
+ "\n"
+ "Options:\n"
+ " -d, --dev_size size of filessytem on device, in bytes \n"
+ " -o, --offset offset to probe, in bytes\n"
+ " -y, --yes Recover without prompting\n"
+ " -v, --verbose Increase logging level\n"
+ " -h, --help display this help and exit\n"
+ "Report bugs to <linux-bcachefs@vger.kernel.org>");
+ exit(EXIT_SUCCESS);
+}
+
+int cmd_recover_super(int argc, char *argv[])
+{
+ static const struct option longopts[] = {
+ { "dev_size", 1, NULL, 'd' },
+ { "offset", 1, NULL, 'o' },
+ { "yes", 0, NULL, 'y' },
+ { "verbose", 0, NULL, 'v' },
+ { "help", 0, NULL, 'h' },
+ { NULL }
+ };
+ u64 dev_size = 0, offset = 0;
+ bool yes = false, verbose = false;
+ int opt;
+
+ while ((opt = getopt_long(argc, argv, "d:o:yvh", longopts, NULL)) != -1)
+ switch (opt) {
+ case 'd':
+ if (bch2_strtoull_h(optarg, &dev_size))
+ die("invalid offset");
+ break;
+ case 'o':
+ if (bch2_strtoull_h(optarg, &offset))
+ die("invalid offset");
+
+ if (offset & 511)
+ die("offset must be a multiple of 512");
+ break;
+ case 'y':
+ yes = true;
+ break;
+ case 'v':
+ verbose = true;
+ break;
+ case 'h':
+ recover_super_usage();
+ break;
+ }
+ args_shift(optind);
+
+ char *dev_path = arg_pop();
+ if (!dev_path)
+ die("please supply a device");
+ if (argc)
+ die("too many arguments");
+
+ int dev_fd = xopen(dev_path, O_RDWR);
+
+ if (!dev_size)
+ dev_size = get_size(dev_fd);
+
+ probed_sb_list sbs = {};
+
+ if (offset) {
+ probe_one_super(dev_fd, SUPERBLOCK_SIZE_DEFAULT, offset, &sbs, verbose);
+ } else {
+ unsigned scan_len = 16 << 20; /* 16MB, start and end of device */
+
+ probe_sb_range(dev_fd, 4096, scan_len, &sbs, verbose);
+ probe_sb_range(dev_fd, dev_size - scan_len, dev_size, &sbs, verbose);
+ }
+
+ if (!sbs.nr) {
+ printf("Found no bcachefs superblocks\n");
+ exit(EXIT_FAILURE);
+ }
+
+ struct bch_sb *best = NULL;
+ darray_for_each(sbs, sb)
+ if (!best || bch2_sb_time_cmp(best, *sb) < 0)
+ best = *sb;
+
+ struct printbuf buf = PRINTBUF;
+ bch2_sb_to_text(&buf, best, true, BIT_ULL(BCH_SB_FIELD_members_v2));
+
+ printf("Found superblock:\n%s", buf.buf);
+ printf("Recover?");
+
+ if (yes || ask_yn())
+ bch2_super_write(dev_fd, best);
+
+ printbuf_exit(&buf);
+ darray_for_each(sbs, sb)
+ kfree(*sb);
+ darray_exit(&sbs);
+
+ return 0;
+}
diff --git a/c_src/cmds.h b/c_src/cmds.h
index 9de87a18..9502d539 100644
--- a/c_src/cmds.h
+++ b/c_src/cmds.h
@@ -11,6 +11,7 @@
int cmd_format(int argc, char *argv[]);
int cmd_show_super(int argc, char *argv[]);
+int cmd_recover_super(int argc, char *argv[]);
int cmd_reset_counters(int argc, char *argv[]);
int cmd_set_option(int argc, char *argv[]);
diff --git a/c_src/libbcachefs.c b/c_src/libbcachefs.c
index cdb5f7f6..c3af991b 100644
--- a/c_src/libbcachefs.c
+++ b/c_src/libbcachefs.c
@@ -31,10 +31,10 @@
#define NSEC_PER_SEC 1000000000L
-static void init_layout(struct bch_sb_layout *l,
- unsigned block_size,
- unsigned sb_size,
- u64 sb_start, u64 sb_end)
+void bch2_sb_layout_init(struct bch_sb_layout *l,
+ unsigned block_size,
+ unsigned sb_size,
+ u64 sb_start, u64 sb_end)
{
u64 sb_pos = sb_start;
unsigned i;
@@ -307,9 +307,9 @@ struct bch_sb *bch2_format(struct bch_opt_strs fs_opt_strs,
i->sb_end = size_sectors;
}
- init_layout(&sb.sb->layout, fs_opts.block_size,
- opts.superblock_size,
- i->sb_offset, i->sb_end);
+ bch2_sb_layout_init(&sb.sb->layout, fs_opts.block_size,
+ opts.superblock_size,
+ i->sb_offset, i->sb_end);
/*
* Also create a backup superblock at the end of the disk:
diff --git a/c_src/libbcachefs.h b/c_src/libbcachefs.h
index ff754c4f..026a3def 100644
--- a/c_src/libbcachefs.h
+++ b/c_src/libbcachefs.h
@@ -79,6 +79,9 @@ static inline struct dev_opts dev_opts_default()
};
}
+void bch2_sb_layout_init(struct bch_sb_layout *,
+ unsigned, unsigned, u64, u64);
+
u64 bch2_pick_bucket_size(struct bch_opts, struct dev_opts *);
void bch2_check_bucket_size(struct bch_opts, struct dev_opts *);
diff --git a/src/bcachefs.rs b/src/bcachefs.rs
index 417cb01e..548add0a 100644
--- a/src/bcachefs.rs
+++ b/src/bcachefs.rs
@@ -60,6 +60,7 @@ fn handle_c_command(mut argv: Vec<String>, symlink_cmd: Option<&str>) -> i32 {
"set-passphrase" => c::cmd_set_passphrase(argc, argv),
"set-file-option" => c::cmd_setattr(argc, argv),
"show-super" => c::cmd_show_super(argc, argv),
+ "recover-super" => c::cmd_recover_super(argc, argv),
"unlock" => c::cmd_unlock(argc, argv),
"version" => c::cmd_version(argc, argv),