btrfs-progs: rescue: Introduce fix-device-size

Introduce new subcommand 'fix-device-size' to the rescue group, to fix
device size alignment-related problems.

Especially for people unable to mount their fs with super::total_bytes
mismatch, this tool will fix the problems and let the mount continue.

Reported-by: Asif Youssuff <yoasif@gmail.com>
Reported-by: Rich Rauenzahn <rrauenza@gmail.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>

diff --git a/Documentation/btrfs-rescue.asciidoc b/Documentation/btrfs-rescue.asciidoc
index 24b619c..815abe3 100644 (file)
--- a/Documentation/btrfs-rescue.asciidoc
+++ b/Documentation/btrfs-rescue.asciidoc
@@ -73,6 +73,35 @@ the log and the filesystem may be mounted normally again. The keywords to look
 for are 'open_ctree' which says that it's during mount and function names
 that contain 'replay', 'recover' or 'log_tree'.
 
+*fix-device-size* <device>::
+fix device size and super block total bytes
++
+This command will fix the following problems, by re-aligning all devices' total
+bytes and re-calculating super block total bytes.
++
+1. Newer kernel refuse to mount btrfs caused by mismatch super block total bytes
++
+----
+BTRFS error (device sdb): super_total_bytes 92017859088384 mismatch with fs_devices total_rw_bytes 92017859094528
+----
++
+2. Noisy kernel warning for newer kernels
++
+----
+WARNING: CPU: 3 PID: 439 at fs/btrfs/ctree.h:1559 btrfs_update_device+0x1c5/0x1d0 [btrfs]
+----
++
+And the corresponding line is the `WARN_ON()` line below:
++
+----
+{
+       BUILD_BUG_ON(sizeof(u64) !=
+                    sizeof(((struct btrfs_dev_item *)0))->total_bytes);
+       WARN_ON(!IS_ALIGNED(val, eb->fs_info->sectorsize));
+       btrfs_set_64(eb, s, offsetof(struct btrfs_dev_item, total_bytes), val);
+}
+----
+
 EXIT STATUS
 -----------
 *btrfs rescue* returns a zero exit status if it succeeds. Non zero is

diff --git a/cmds-rescue.c b/cmds-rescue.c
index 4bc798d..c40088a 100644 (file)
--- a/cmds-rescue.c
+++ b/cmds-rescue.c
@@ -20,6 +20,7 @@
 
 #include <getopt.h>
 #include "ctree.h"
+#include "volumes.h"
 #include "transaction.h"
 #include "disk-io.h"
 #include "commands.h"
@@ -202,6 +203,51 @@ out:
        return !!ret;
 }
 
+static const char * const cmd_rescue_fix_device_size_usage[] = {
+       "btrfs rescue fix-device-size <device>",
+       "Re-align device and super block sizes. Usable if newer kernel refuse to mount it due to mismatch super size",
+       "",
+       NULL
+};
+
+static int cmd_rescue_fix_device_size(int argc, char **argv)
+{
+       struct btrfs_fs_info *fs_info;
+       char *devname;
+       int ret;
+
+       clean_args_no_options(argc, argv, cmd_rescue_fix_device_size_usage);
+
+       if (check_argc_exact(argc, 2))
+               usage(cmd_rescue_fix_device_size_usage);
+
+       devname = argv[optind];
+       ret = check_mounted(devname);
+       if (ret < 0) {
+               error("could not check mount status: %s", strerror(-ret));
+               goto out;
+       } else if (ret) {
+               error("%s is currently mounted", devname);
+               ret = -EBUSY;
+               goto out;
+       }
+
+       fs_info = open_ctree_fs_info(devname, 0, 0, 0, OPEN_CTREE_WRITES |
+                                    OPEN_CTREE_PARTIAL);
+       if (!fs_info) {
+               error("could not open btrfs");
+               ret = -EIO;
+               goto out;
+       }
+
+       ret = btrfs_fix_device_and_super_size(fs_info);
+       if (ret > 0)
+               ret = 0;
+       close_ctree(fs_info->tree_root);
+out:
+       return !!ret;
+}
+
 static const char rescue_cmd_group_info[] =
 "toolbox for specific rescue operations";
 
@@ -212,6 +258,8 @@ const struct cmd_group rescue_cmd_group = {
                { "super-recover", cmd_rescue_super_recover,
                        cmd_rescue_super_recover_usage, NULL, 0},
                { "zero-log", cmd_rescue_zero_log, cmd_rescue_zero_log_usage, NULL, 0},
+               { "fix-device-size", cmd_rescue_fix_device_size,
+                       cmd_rescue_fix_device_size_usage, NULL, 0},
                NULL_CMD_STRUCT
        }
 };

diff --git a/volumes.c b/volumes.c
index f6d5d35..ce3a540 100644 (file)
--- a/volumes.c
+++ b/volumes.c
@@ -2477,3 +2477,60 @@ int btrfs_fix_super_size(struct btrfs_fs_info *fs_info)
                old_bytes, total_bytes);
        return 1;
 }
+
+/*
+ * Return 0 if all devices and super block sizes are good
+ * Return >0 if any device/super size problem was found, but fixed
+ * Return <0 if something wrong happened during fixing
+ */
+int btrfs_fix_device_and_super_size(struct btrfs_fs_info *fs_info)
+{
+       struct btrfs_device *device;
+       struct list_head *dev_list = &fs_info->fs_devices->devices;
+       bool have_bad_value = false;
+       int ret;
+
+       /* Seed device is not supported yet */
+       if (fs_info->fs_devices->seed) {
+               error("fixing device size with seed device is not supported yet");
+               return -EOPNOTSUPP;
+       }
+
+       /* All devices must be set up before repairing */
+       if (list_empty(dev_list)) {
+               error("no device found");
+               return -ENODEV;
+       }
+       list_for_each_entry(device, dev_list, dev_list) {
+               if (device->fd == -1 || !device->writeable) {
+                       error("devid %llu is missing or not writeable",
+                             device->devid);
+                       error(
+       "fixing device size needs all device(s) to be present and writeable");
+                       return -ENODEV;
+               }
+       }
+
+       /* Repair total_bytes of each device */
+       list_for_each_entry(device, dev_list, dev_list) {
+               ret = btrfs_fix_device_size(fs_info, device);
+               if (ret < 0)
+                       return ret;
+               if (ret > 0)
+                       have_bad_value = true;
+       }
+
+       /* Repair super total_byte */
+       ret = btrfs_fix_super_size(fs_info);
+       if (ret > 0)
+               have_bad_value = true;
+       if (have_bad_value) {
+               printf(
+       "Fixed unaligned/mismatched total_bytes for super block and device items\n");
+               ret = 1;
+       } else {
+               printf("No device size related problem found\n");
+               ret = 0;
+       }
+       return ret;
+}

diff --git a/volumes.h b/volumes.h
index d5bb5f8..11572e7 100644 (file)
--- a/volumes.h
+++ b/volumes.h
@@ -248,4 +248,5 @@ u64 btrfs_stripe_length(struct btrfs_fs_info *fs_info,
 int btrfs_fix_device_size(struct btrfs_fs_info *fs_info,
                          struct btrfs_device *device);
 int btrfs_fix_super_size(struct btrfs_fs_info *fs_info);
+int btrfs_fix_device_and_super_size(struct btrfs_fs_info *fs_info);
 #endif