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btrfs: remove device item and update super block in the same transaction
[ Upstream commit bbac58698a
]
[BUG]
There is a report that a btrfs has a bad super block num devices.
This makes btrfs to reject the fs completely.
BTRFS error (device sdd3): super_num_devices 3 mismatch with num_devices 2 found here
BTRFS error (device sdd3): failed to read chunk tree: -22
BTRFS error (device sdd3): open_ctree failed
[CAUSE]
During btrfs device removal, chunk tree and super block num devs are
updated in two different transactions:
btrfs_rm_device()
|- btrfs_rm_dev_item(device)
| |- trans = btrfs_start_transaction()
| | Now we got transaction X
| |
| |- btrfs_del_item()
| | Now device item is removed from chunk tree
| |
| |- btrfs_commit_transaction()
| Transaction X got committed, super num devs untouched,
| but device item removed from chunk tree.
| (AKA, super num devs is already incorrect)
|
|- cur_devices->num_devices--;
|- cur_devices->total_devices--;
|- btrfs_set_super_num_devices()
All those operations are not in transaction X, thus it will
only be written back to disk in next transaction.
So after the transaction X in btrfs_rm_dev_item() committed, but before
transaction X+1 (which can be minutes away), a power loss happen, then
we got the super num mismatch.
[FIX]
Instead of starting and committing a transaction inside
btrfs_rm_dev_item(), start a transaction in side btrfs_rm_device() and
pass it to btrfs_rm_dev_item().
And only commit the transaction after everything is done.
Reported-by: Luca Béla Palkovics <luca.bela.palkovics@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CA+8xDSpvdm_U0QLBAnrH=zqDq_cWCOH5TiV46CKmp3igr44okQ@mail.gmail.com/
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
f75534a71a
commit
72fa2ea3e0
1 changed files with 28 additions and 37 deletions
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@ -1942,23 +1942,18 @@ static void update_dev_time(const char *device_path)
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path_put(&path);
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}
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static int btrfs_rm_dev_item(struct btrfs_device *device)
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static int btrfs_rm_dev_item(struct btrfs_trans_handle *trans,
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struct btrfs_device *device)
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{
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struct btrfs_root *root = device->fs_info->chunk_root;
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int ret;
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struct btrfs_path *path;
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struct btrfs_key key;
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struct btrfs_trans_handle *trans;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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trans = btrfs_start_transaction(root, 0);
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if (IS_ERR(trans)) {
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btrfs_free_path(path);
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return PTR_ERR(trans);
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}
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key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
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key.type = BTRFS_DEV_ITEM_KEY;
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key.offset = device->devid;
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@ -1969,21 +1964,12 @@ static int btrfs_rm_dev_item(struct btrfs_device *device)
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if (ret) {
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if (ret > 0)
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ret = -ENOENT;
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btrfs_abort_transaction(trans, ret);
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btrfs_end_transaction(trans);
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goto out;
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}
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ret = btrfs_del_item(trans, root, path);
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if (ret) {
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btrfs_abort_transaction(trans, ret);
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btrfs_end_transaction(trans);
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}
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out:
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btrfs_free_path(path);
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if (!ret)
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ret = btrfs_commit_transaction(trans);
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return ret;
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}
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@ -2124,6 +2110,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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struct btrfs_dev_lookup_args *args,
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struct block_device **bdev, fmode_t *mode)
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{
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struct btrfs_trans_handle *trans;
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struct btrfs_device *device;
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struct btrfs_fs_devices *cur_devices;
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struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
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@ -2139,7 +2126,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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ret = btrfs_check_raid_min_devices(fs_info, num_devices - 1);
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if (ret)
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goto out;
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return ret;
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device = btrfs_find_device(fs_info->fs_devices, args);
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if (!device) {
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@ -2147,27 +2134,22 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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ret = BTRFS_ERROR_DEV_MISSING_NOT_FOUND;
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else
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ret = -ENOENT;
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goto out;
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return ret;
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}
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if (btrfs_pinned_by_swapfile(fs_info, device)) {
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btrfs_warn_in_rcu(fs_info,
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"cannot remove device %s (devid %llu) due to active swapfile",
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rcu_str_deref(device->name), device->devid);
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ret = -ETXTBSY;
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goto out;
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return -ETXTBSY;
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}
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if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
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ret = BTRFS_ERROR_DEV_TGT_REPLACE;
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goto out;
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}
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if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
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return BTRFS_ERROR_DEV_TGT_REPLACE;
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if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
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fs_info->fs_devices->rw_devices == 1) {
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ret = BTRFS_ERROR_DEV_ONLY_WRITABLE;
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goto out;
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}
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fs_info->fs_devices->rw_devices == 1)
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return BTRFS_ERROR_DEV_ONLY_WRITABLE;
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if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
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mutex_lock(&fs_info->chunk_mutex);
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@ -2182,14 +2164,22 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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if (ret)
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goto error_undo;
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/*
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* TODO: the superblock still includes this device in its num_devices
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* counter although write_all_supers() is not locked out. This
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* could give a filesystem state which requires a degraded mount.
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*/
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ret = btrfs_rm_dev_item(device);
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if (ret)
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trans = btrfs_start_transaction(fs_info->chunk_root, 0);
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if (IS_ERR(trans)) {
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ret = PTR_ERR(trans);
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goto error_undo;
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}
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ret = btrfs_rm_dev_item(trans, device);
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if (ret) {
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/* Any error in dev item removal is critical */
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btrfs_crit(fs_info,
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"failed to remove device item for devid %llu: %d",
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device->devid, ret);
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btrfs_abort_transaction(trans, ret);
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btrfs_end_transaction(trans);
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return ret;
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}
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clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
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btrfs_scrub_cancel_dev(device);
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@ -2264,7 +2254,8 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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free_fs_devices(cur_devices);
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}
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out:
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ret = btrfs_commit_transaction(trans);
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return ret;
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error_undo:
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@ -2276,7 +2267,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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device->fs_devices->rw_devices++;
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mutex_unlock(&fs_info->chunk_mutex);
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}
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goto out;
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return ret;
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}
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void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_device *srcdev)
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