![Josef Bacik](/assets/img/avatar_default.png)
There's a bug in snapshot deletion where we won't update the drop_progress key if we're in the UPDATE_BACKREF stage. This is a problem because we could drop refs for blocks we know don't belong to ours. If we crash or umount at the right time we could experience messages such as the following when snapshot deletion resumes BTRFS error (device dm-3): unable to find ref byte nr 66797568 parent 0 root 258 owner 1 offset 0 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 16052 at fs/btrfs/extent-tree.c:7108 __btrfs_free_extent.isra.78+0x62c/0xb30 [btrfs] CPU: 3 PID: 16052 Comm: umount Tainted: G W OE 5.0.0-rc4+ #147 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./890FX Deluxe5, BIOS P1.40 05/03/2011 RIP: 0010:__btrfs_free_extent.isra.78+0x62c/0xb30 [btrfs] RSP: 0018:ffffc90005cd7b18 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff88842fade680 RSI: ffff88842fad6b18 RDI: ffff88842fad6b18 RBP: ffffc90005cd7bc8 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000001 R11: ffffffff822696b8 R12: 0000000003fb4000 R13: 0000000000000001 R14: 0000000000000102 R15: ffff88819c9d67e0 FS: 00007f08bb138fc0(0000) GS:ffff88842fac0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8f5d861ea0 CR3: 00000003e99fe000 CR4: 00000000000006e0 Call Trace: ? _raw_spin_unlock+0x27/0x40 ? btrfs_merge_delayed_refs+0x356/0x3e0 [btrfs] __btrfs_run_delayed_refs+0x75a/0x13c0 [btrfs] ? join_transaction+0x2b/0x460 [btrfs] btrfs_run_delayed_refs+0xf3/0x1c0 [btrfs] btrfs_commit_transaction+0x52/0xa50 [btrfs] ? start_transaction+0xa6/0x510 [btrfs] btrfs_sync_fs+0x79/0x1c0 [btrfs] sync_filesystem+0x70/0x90 generic_shutdown_super+0x27/0x120 kill_anon_super+0x12/0x30 btrfs_kill_super+0x16/0xa0 [btrfs] deactivate_locked_super+0x43/0x70 deactivate_super+0x40/0x60 cleanup_mnt+0x3f/0x80 __cleanup_mnt+0x12/0x20 task_work_run+0x8b/0xc0 exit_to_usermode_loop+0xce/0xd0 do_syscall_64+0x20b/0x210 entry_SYSCALL_64_after_hwframe+0x49/0xbe To fix this simply mark dead roots we read from disk as DEAD and then set the walk_control->restarted flag so we know we have a restarted deletion. From here whenever we try to drop refs for blocks we check to verify our ref is set on them, and if it is not we skip it. Once we find a ref that is set we unset walk_control->restarted since the tree should be in a normal state from then on, and any problems we run into from there are different issues. I tested this with an existing broken fs and my reproducer that creates a broken fs and it fixed both file systems. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
499 lines
13 KiB
C
499 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*/
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#include <linux/err.h>
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#include <linux/uuid.h>
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#include "ctree.h"
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#include "transaction.h"
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#include "disk-io.h"
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#include "print-tree.h"
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/*
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* Read a root item from the tree. In case we detect a root item smaller then
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* sizeof(root_item), we know it's an old version of the root structure and
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* initialize all new fields to zero. The same happens if we detect mismatching
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* generation numbers as then we know the root was once mounted with an older
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* kernel that was not aware of the root item structure change.
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*/
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static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
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struct btrfs_root_item *item)
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{
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uuid_le uuid;
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u32 len;
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int need_reset = 0;
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len = btrfs_item_size_nr(eb, slot);
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read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
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min_t(u32, len, sizeof(*item)));
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if (len < sizeof(*item))
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need_reset = 1;
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if (!need_reset && btrfs_root_generation(item)
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!= btrfs_root_generation_v2(item)) {
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if (btrfs_root_generation_v2(item) != 0) {
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btrfs_warn(eb->fs_info,
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"mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
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}
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need_reset = 1;
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}
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if (need_reset) {
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memset(&item->generation_v2, 0,
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sizeof(*item) - offsetof(struct btrfs_root_item,
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generation_v2));
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uuid_le_gen(&uuid);
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memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
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}
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}
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/*
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* btrfs_find_root - lookup the root by the key.
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* root: the root of the root tree
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* search_key: the key to search
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* path: the path we search
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* root_item: the root item of the tree we look for
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* root_key: the root key of the tree we look for
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*
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* If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
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* of the search key, just lookup the root with the highest offset for a
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* given objectid.
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*
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* If we find something return 0, otherwise > 0, < 0 on error.
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*/
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int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
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struct btrfs_path *path, struct btrfs_root_item *root_item,
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struct btrfs_key *root_key)
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{
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struct btrfs_key found_key;
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struct extent_buffer *l;
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int ret;
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int slot;
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ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
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if (ret < 0)
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return ret;
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if (search_key->offset != -1ULL) { /* the search key is exact */
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if (ret > 0)
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goto out;
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} else {
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BUG_ON(ret == 0); /* Logical error */
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if (path->slots[0] == 0)
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goto out;
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path->slots[0]--;
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ret = 0;
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}
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l = path->nodes[0];
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slot = path->slots[0];
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btrfs_item_key_to_cpu(l, &found_key, slot);
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if (found_key.objectid != search_key->objectid ||
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found_key.type != BTRFS_ROOT_ITEM_KEY) {
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ret = 1;
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goto out;
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}
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if (root_item)
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btrfs_read_root_item(l, slot, root_item);
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if (root_key)
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memcpy(root_key, &found_key, sizeof(found_key));
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out:
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btrfs_release_path(path);
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return ret;
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}
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void btrfs_set_root_node(struct btrfs_root_item *item,
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struct extent_buffer *node)
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{
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btrfs_set_root_bytenr(item, node->start);
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btrfs_set_root_level(item, btrfs_header_level(node));
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btrfs_set_root_generation(item, btrfs_header_generation(node));
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}
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/*
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* copy the data in 'item' into the btree
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*/
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int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
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*root, struct btrfs_key *key, struct btrfs_root_item
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*item)
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{
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struct btrfs_fs_info *fs_info = root->fs_info;
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struct btrfs_path *path;
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struct extent_buffer *l;
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int ret;
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int slot;
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unsigned long ptr;
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u32 old_len;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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ret = btrfs_search_slot(trans, root, key, path, 0, 1);
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if (ret < 0) {
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btrfs_abort_transaction(trans, ret);
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goto out;
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}
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if (ret != 0) {
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btrfs_print_leaf(path->nodes[0]);
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btrfs_crit(fs_info, "unable to update root key %llu %u %llu",
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key->objectid, key->type, key->offset);
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BUG_ON(1);
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}
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l = path->nodes[0];
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slot = path->slots[0];
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ptr = btrfs_item_ptr_offset(l, slot);
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old_len = btrfs_item_size_nr(l, slot);
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/*
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* If this is the first time we update the root item which originated
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* from an older kernel, we need to enlarge the item size to make room
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* for the added fields.
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*/
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if (old_len < sizeof(*item)) {
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btrfs_release_path(path);
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ret = btrfs_search_slot(trans, root, key, path,
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-1, 1);
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if (ret < 0) {
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btrfs_abort_transaction(trans, ret);
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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 < 0) {
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btrfs_abort_transaction(trans, ret);
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goto out;
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}
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btrfs_release_path(path);
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ret = btrfs_insert_empty_item(trans, root, path,
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key, sizeof(*item));
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if (ret < 0) {
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btrfs_abort_transaction(trans, ret);
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goto out;
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}
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l = path->nodes[0];
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slot = path->slots[0];
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ptr = btrfs_item_ptr_offset(l, slot);
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}
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/*
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* Update generation_v2 so at the next mount we know the new root
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* fields are valid.
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*/
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btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
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write_extent_buffer(l, item, ptr, sizeof(*item));
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btrfs_mark_buffer_dirty(path->nodes[0]);
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out:
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btrfs_free_path(path);
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return ret;
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}
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int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
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const struct btrfs_key *key, struct btrfs_root_item *item)
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{
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/*
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* Make sure generation v1 and v2 match. See update_root for details.
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*/
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btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
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return btrfs_insert_item(trans, root, key, item, sizeof(*item));
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}
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int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
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{
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struct btrfs_root *tree_root = fs_info->tree_root;
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struct extent_buffer *leaf;
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struct btrfs_path *path;
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struct btrfs_key key;
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struct btrfs_key root_key;
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struct btrfs_root *root;
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int err = 0;
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int ret;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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key.objectid = BTRFS_ORPHAN_OBJECTID;
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key.type = BTRFS_ORPHAN_ITEM_KEY;
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key.offset = 0;
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root_key.type = BTRFS_ROOT_ITEM_KEY;
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root_key.offset = (u64)-1;
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while (1) {
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ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
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if (ret < 0) {
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err = ret;
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break;
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}
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leaf = path->nodes[0];
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if (path->slots[0] >= btrfs_header_nritems(leaf)) {
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ret = btrfs_next_leaf(tree_root, path);
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if (ret < 0)
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err = ret;
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if (ret != 0)
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break;
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leaf = path->nodes[0];
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}
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btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
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btrfs_release_path(path);
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if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
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key.type != BTRFS_ORPHAN_ITEM_KEY)
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break;
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root_key.objectid = key.offset;
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key.offset++;
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/*
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* The root might have been inserted already, as before we look
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* for orphan roots, log replay might have happened, which
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* triggers a transaction commit and qgroup accounting, which
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* in turn reads and inserts fs roots while doing backref
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* walking.
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*/
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root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
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if (root) {
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WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
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&root->state));
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if (btrfs_root_refs(&root->root_item) == 0) {
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set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
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btrfs_add_dead_root(root);
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}
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continue;
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}
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root = btrfs_read_fs_root(tree_root, &root_key);
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err = PTR_ERR_OR_ZERO(root);
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if (err && err != -ENOENT) {
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break;
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} else if (err == -ENOENT) {
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struct btrfs_trans_handle *trans;
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btrfs_release_path(path);
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trans = btrfs_join_transaction(tree_root);
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if (IS_ERR(trans)) {
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err = PTR_ERR(trans);
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btrfs_handle_fs_error(fs_info, err,
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"Failed to start trans to delete orphan item");
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break;
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}
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err = btrfs_del_orphan_item(trans, tree_root,
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root_key.objectid);
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btrfs_end_transaction(trans);
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if (err) {
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btrfs_handle_fs_error(fs_info, err,
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"Failed to delete root orphan item");
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break;
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}
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continue;
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}
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err = btrfs_init_fs_root(root);
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if (err) {
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btrfs_free_fs_root(root);
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break;
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}
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set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
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err = btrfs_insert_fs_root(fs_info, root);
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if (err) {
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BUG_ON(err == -EEXIST);
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btrfs_free_fs_root(root);
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break;
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}
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if (btrfs_root_refs(&root->root_item) == 0) {
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set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
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btrfs_add_dead_root(root);
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}
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}
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btrfs_free_path(path);
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return err;
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}
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/* drop the root item for 'key' from the tree root */
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int btrfs_del_root(struct btrfs_trans_handle *trans,
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const struct btrfs_key *key)
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{
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struct btrfs_root *root = trans->fs_info->tree_root;
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struct btrfs_path *path;
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int ret;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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ret = btrfs_search_slot(trans, root, key, path, -1, 1);
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if (ret < 0)
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goto out;
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BUG_ON(ret != 0);
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ret = btrfs_del_item(trans, root, path);
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out:
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btrfs_free_path(path);
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return ret;
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}
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int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
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u64 ref_id, u64 dirid, u64 *sequence, const char *name,
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int name_len)
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{
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struct btrfs_root *tree_root = trans->fs_info->tree_root;
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struct btrfs_path *path;
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struct btrfs_root_ref *ref;
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struct extent_buffer *leaf;
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struct btrfs_key key;
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unsigned long ptr;
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int err = 0;
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int ret;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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key.objectid = root_id;
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key.type = BTRFS_ROOT_BACKREF_KEY;
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key.offset = ref_id;
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again:
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ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
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BUG_ON(ret < 0);
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if (ret == 0) {
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leaf = path->nodes[0];
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ref = btrfs_item_ptr(leaf, path->slots[0],
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struct btrfs_root_ref);
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WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
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WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
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ptr = (unsigned long)(ref + 1);
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WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
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*sequence = btrfs_root_ref_sequence(leaf, ref);
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ret = btrfs_del_item(trans, tree_root, path);
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if (ret) {
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err = ret;
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goto out;
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}
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} else
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err = -ENOENT;
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if (key.type == BTRFS_ROOT_BACKREF_KEY) {
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btrfs_release_path(path);
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key.objectid = ref_id;
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key.type = BTRFS_ROOT_REF_KEY;
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key.offset = root_id;
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goto again;
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}
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out:
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btrfs_free_path(path);
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return err;
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}
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/*
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* add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
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* or BTRFS_ROOT_BACKREF_KEY.
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*
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* The dirid, sequence, name and name_len refer to the directory entry
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* that is referencing the root.
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*
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* For a forward ref, the root_id is the id of the tree referencing
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* the root and ref_id is the id of the subvol or snapshot.
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*
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* For a back ref the root_id is the id of the subvol or snapshot and
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* ref_id is the id of the tree referencing it.
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*
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* Will return 0, -ENOMEM, or anything from the CoW path
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*/
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int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
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u64 ref_id, u64 dirid, u64 sequence, const char *name,
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int name_len)
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{
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struct btrfs_root *tree_root = trans->fs_info->tree_root;
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struct btrfs_key key;
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int ret;
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struct btrfs_path *path;
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struct btrfs_root_ref *ref;
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struct extent_buffer *leaf;
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unsigned long ptr;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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key.objectid = root_id;
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key.type = BTRFS_ROOT_BACKREF_KEY;
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key.offset = ref_id;
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again:
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ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
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sizeof(*ref) + name_len);
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if (ret) {
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btrfs_abort_transaction(trans, ret);
|
|
btrfs_free_path(path);
|
|
return ret;
|
|
}
|
|
|
|
leaf = path->nodes[0];
|
|
ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
|
|
btrfs_set_root_ref_dirid(leaf, ref, dirid);
|
|
btrfs_set_root_ref_sequence(leaf, ref, sequence);
|
|
btrfs_set_root_ref_name_len(leaf, ref, name_len);
|
|
ptr = (unsigned long)(ref + 1);
|
|
write_extent_buffer(leaf, name, ptr, name_len);
|
|
btrfs_mark_buffer_dirty(leaf);
|
|
|
|
if (key.type == BTRFS_ROOT_BACKREF_KEY) {
|
|
btrfs_release_path(path);
|
|
key.objectid = ref_id;
|
|
key.type = BTRFS_ROOT_REF_KEY;
|
|
key.offset = root_id;
|
|
goto again;
|
|
}
|
|
|
|
btrfs_free_path(path);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Old btrfs forgets to init root_item->flags and root_item->byte_limit
|
|
* for subvolumes. To work around this problem, we steal a bit from
|
|
* root_item->inode_item->flags, and use it to indicate if those fields
|
|
* have been properly initialized.
|
|
*/
|
|
void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
|
|
{
|
|
u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
|
|
|
|
if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
|
|
inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
|
|
btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
|
|
btrfs_set_root_flags(root_item, 0);
|
|
btrfs_set_root_limit(root_item, 0);
|
|
}
|
|
}
|
|
|
|
void btrfs_update_root_times(struct btrfs_trans_handle *trans,
|
|
struct btrfs_root *root)
|
|
{
|
|
struct btrfs_root_item *item = &root->root_item;
|
|
struct timespec64 ct;
|
|
|
|
ktime_get_real_ts64(&ct);
|
|
spin_lock(&root->root_item_lock);
|
|
btrfs_set_root_ctransid(item, trans->transid);
|
|
btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
|
|
btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
|
|
spin_unlock(&root->root_item_lock);
|
|
}
|