This patch introduces functions to repair device size related problems,
including:
1) Unaligned total_bytes of dev_item
v4.14-rc kernel introduced total_bytes alignment checker.
However older kernel device add/shrink doesn't align these members.
This will cause kernel warning every time dev_item get updated.
Although it can be fixed by shrinking device on latest kernel or
use manually aligned size on older kernel, a fallback method in
btrfs-progs won't hurt.
2) Mismatch super->total_bytes
There are some reports about unmountable fs, due to mismatched
super->total_bytes.
And normal kernel device shrink won't help since it only modify the
total_bytes by the size changed, not re-calculating it.
The root cause is still under investigation, but at least to fix it
in btrfs-progs
Fix all of them by manually rounding down total_bytes of each device, and
recalculate super->total_bytes using all existing devices.
Reported-by: Asif Youssuff <yoasif@xxxxxxxxx>
Reported-by: Rich Rauenzahn <rrauenza@xxxxxxxxx>
Signed-off-by: Qu Wenruo <quwenruo.btrfs@xxxxxxx>
---
cmds-check.c | 191 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 191 insertions(+)
diff --git a/cmds-check.c b/cmds-check.c
index 0c08618ed701..007781fa5d1b 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -12885,6 +12885,197 @@ close_out:
return ret;
}
+/*
+ * Return 0 if DEV_ITEM for @device is good
+ * Return >0 if DEV_ITEM for @device has unaligned value and fixed
+ * Return <0 if we failed to fix the unaligned value
+ */
+static int reset_one_dev_size(struct btrfs_fs_info *fs_info,
+ struct btrfs_device *device)
+{
+ struct btrfs_trans_handle *trans;
+ struct btrfs_key key;
+ struct btrfs_path path;
+ struct btrfs_root *chunk_root = fs_info->chunk_root;
+ struct btrfs_dev_item *di;
+ u64 old_bytes = device->total_bytes;
+ int ret;
+
+ if (IS_ALIGNED(device->total_bytes, fs_info->sectorsize))
+ return 0;
+
+ /* Align the in-memory total_bytes first, and use it later */
+ device->total_bytes = round_down(device->total_bytes,
+ fs_info->sectorsize);
+
+ key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
+ key.type = BTRFS_DEV_ITEM_KEY;
+ key.offset = device->devid;
+
+ trans = btrfs_start_transaction(chunk_root, 1);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ error("error starting transaction: %d (%s)",
+ ret, strerror(-ret));
+ return ret;
+ }
+
+ btrfs_init_path(&path);
+ ret = btrfs_search_slot(trans, chunk_root, &key, &path, 0, 1);
+ if (ret > 0) {
+ error("failed to find DEV_ITEM for devid %llu",
+ device->devid);
+ ret = -ENOENT;
+ goto err;
+ }
+ if (ret < 0) {
+ error("failed to search chunk root: %d (%s)",
+ ret, strerror(-ret));
+ goto err;
+ }
+ di = btrfs_item_ptr(path.nodes[0], path.slots[0],
+ struct btrfs_dev_item);
+ btrfs_set_device_total_bytes(path.nodes[0], di, device->total_bytes);
+ btrfs_mark_buffer_dirty(path.nodes[0]);
+ ret = btrfs_commit_transaction(trans, chunk_root);
+ if (ret < 0) {
+ error("failed to commit current transaction: %d (%s)",
+ ret, strerror(-ret));
+ btrfs_release_path(&path);
+ return ret;
+ }
+ btrfs_release_path(&path);
+ printf("Fixed device size for devid %llu, old size: %llu new size: %llu\n",
+ device->devid, old_bytes, device->total_bytes);
+ return 1;
+
+err:
+ /* We haven't modified anything, it's OK to commit current trans */
+ btrfs_commit_transaction(trans, chunk_root);
+ btrfs_release_path(&path);
+ return ret;
+}
+
+/*
+ * Return 0 if super block total bytes matches with device total_bytes
+ * Return >0 if super block has mismatch total_bytes and fixed
+ * Return <0 if we failed to fix the mismatch total_bytes
+ */
+static int reset_super_total_bytes(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_trans_handle *trans;
+ struct btrfs_device *device;
+ struct list_head *dev_list = &fs_info->fs_devices->devices;
+ u64 total_bytes = 0;
+ u64 old_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+ int ret;
+
+ list_for_each_entry(device, dev_list, dev_list)
+ total_bytes += device->total_bytes;
+
+ if (total_bytes == old_bytes)
+ return 0;
+
+ /* Just in case */
+ if (!IS_ALIGNED(total_bytes, fs_info->sectorsize)) {
+ error("final total_bytes still not aligned to %u, please report a bug to btrfs mail list",
+ fs_info->sectorsize);
+ return -EUCLEAN;
+ }
+
+ btrfs_set_super_total_bytes(fs_info->super_copy, total_bytes);
+
+ /* Commit transaction to update all super blocks */
+ trans = btrfs_start_transaction(fs_info->tree_root, 1);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ error("error starting transaction: %d (%s)",
+ ret, strerror(-ret));
+ return ret;
+ }
+ ret = btrfs_commit_transaction(trans, fs_info->tree_root);
+ if (ret < 0) {
+ error("failed to commit current transaction: %d (%s)",
+ ret, strerror(-ret));
+ return ret;
+ }
+ printf("Fixed super total bytes, old size: %llu new size: %llu\n",
+ old_bytes, total_bytes);
+ return 1;
+}
+
+/*
+ * Repair device size related problems, including:
+ * 1) Unaligned total_bytes of dev_item
+ * v4.14-rc kernel introduced total_bytes alignment checker.
+ * However older kernel device add/shrink doesn't restrictly align
+ * these members.
+ * This will cause kernel warning everytime dev_item get updated.
+ *
+ * Although it can be fixed by shrinking device on latest kernel or
+ * use manually aligned size on older kernel, a fallback method in
+ * btrfs-progs won't hurt.
+ *
+ * 2) Mismatch super->total_bytes
+ * Due to similar situation, super->total_bytes can be mismatch with
+ * total size of all devices.
+ * This will cause the filesystem unable to be mounted with v4.14-rc kernel.
+ *
+ * Add such fixer in btrfs-progs as a fallback method.
+ *
+ * Fix all of them by manually rounding down total_bytes of each device, and
+ * recalculate super->total_bytes using all existing devices.
+ */
+static int reset_devs_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 support yet */
+ if (fs_info->fs_devices->seed) {
+ error("resetting device size with seed device is not supported yet");
+ return -ENOTTY;
+ }
+
+ /* All devices must be on-line before reparing */
+ 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("device with devid %llu is missing or not writeable",
+ device->devid);
+ error("resetting device size needs all device(s) present and writeable");
+ return -ENODEV;
+ }
+ }
+
+ /* Repair total_bytes of each device */
+ list_for_each_entry(device, dev_list, dev_list) {
+ ret = reset_one_dev_size(fs_info, device);
+ if (ret < 0)
+ return ret;
+ if (ret > 0)
+ have_bad_value = true;
+ }
+
+ /* Repair super total_byte */
+ ret = reset_super_total_bytes(fs_info);
+ if (ret > 0)
+ have_bad_value = true;
+ if (have_bad_value) {
+ printf("Fixed unaligned/mismatch total_bytes for superblock and device item\n");
+ ret = 1;
+ } else {
+ printf("No device size related problem found\n");
+ ret = 0;
+ }
+ return ret;
+}
+
const char * const cmd_check_usage[] = {
"btrfs check [options] <device>",
"Check structural integrity of a filesystem (unmounted).",
--
2.14.2
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