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[174.109.172.136]) by smtp.gmail.com with ESMTPSA id i18sm1848135qka.50.2020.09.28.11.35.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2020 11:35:03 -0700 (PDT) From: Josef Bacik To: linux-btrfs@vger.kernel.org, kernel-team@fb.com Subject: [PATCH v2 3/5] btrfs: introduce rescue=ignorebadroots Date: Mon, 28 Sep 2020 14:34:55 -0400 Message-Id: X-Mailer: git-send-email 2.26.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org In the face of extent root corruption, or any other core fs wide root corruption we will fail to mount the file system. This makes recovery kind of a pain, because you need to fall back to userspace tools to scrape off data. Instead provide a mechanism to gracefully handle bad roots, so we can at least mount read-only and possibly recover data from the file system. Signed-off-by: Josef Bacik --- fs/btrfs/block-group.c | 48 +++++++++++++++++++++++++++++++ fs/btrfs/block-rsv.c | 8 ++++++ fs/btrfs/compression.c | 3 +- fs/btrfs/ctree.h | 1 + fs/btrfs/disk-io.c | 65 ++++++++++++++++++++++++++---------------- fs/btrfs/file-item.c | 3 +- fs/btrfs/inode.c | 6 +++- fs/btrfs/super.c | 11 ++++++- fs/btrfs/volumes.c | 13 +++++++++ 9 files changed, 130 insertions(+), 28 deletions(-) diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index c0f1d6818df7..7e32f7820543 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1985,6 +1985,51 @@ static int read_one_block_group(struct btrfs_fs_info *info, return ret; } +static int fill_dummy_bgs(struct btrfs_fs_info *fs_info) +{ + struct extent_map_tree *em_tree = &fs_info->mapping_tree; + struct extent_map *em; + struct map_lookup *map; + struct btrfs_block_group *bg; + struct btrfs_space_info *space_info; + struct rb_node *node; + int ret = 0; + + for (node = rb_first_cached(&em_tree->map); node; + node = rb_next(node)) { + em = rb_entry(node, struct extent_map, rb_node); + map = em->map_lookup; + bg = btrfs_create_block_group_cache(fs_info, em->start); + if (!bg) { + ret = -ENOMEM; + break; + } + + /* Fill dummy cache as FULL */ + bg->length = em->len; + bg->flags = map->type; + bg->last_byte_to_unpin = (u64)-1; + bg->cached = BTRFS_CACHE_FINISHED; + bg->used = em->len; + bg->flags = map->type; + ret = btrfs_add_block_group_cache(fs_info, bg); + if (ret) { + btrfs_remove_free_space_cache(bg); + btrfs_put_block_group(bg); + break; + } + btrfs_update_space_info(fs_info, bg->flags, em->len, em->len, + 0, &space_info); + bg->space_info = space_info; + link_block_group(bg); + + set_avail_alloc_bits(fs_info, bg->flags); + } + if (!ret) + btrfs_init_global_block_rsv(fs_info); + return ret; +} + int btrfs_read_block_groups(struct btrfs_fs_info *info) { struct btrfs_path *path; @@ -1995,6 +2040,9 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) int need_clear = 0; u64 cache_gen; + if (!info->extent_root) + return fill_dummy_bgs(info); + key.objectid = 0; key.offset = 0; key.type = BTRFS_BLOCK_GROUP_ITEM_KEY; diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c index 7e1549a84fcc..58b38912498d 100644 --- a/fs/btrfs/block-rsv.c +++ b/fs/btrfs/block-rsv.c @@ -426,6 +426,14 @@ void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info) fs_info->delayed_block_rsv.space_info = space_info; fs_info->delayed_refs_rsv.space_info = space_info; + /* + * Our various recovery options can leave us with NULL roots, so check + * here and just bail before we go deref'ing NULLS everywhere. + */ + if (!fs_info->extent_root || !fs_info->csum_root || + !fs_info->dev_root || !fs_info->chunk_root || !fs_info->tree_root) + return; + fs_info->extent_root->block_rsv = &fs_info->delayed_refs_rsv; fs_info->csum_root->block_rsv = &fs_info->delayed_refs_rsv; fs_info->dev_root->block_rsv = &fs_info->global_block_rsv; diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 7e1eb57b923c..46dc621f599d 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -150,7 +150,8 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio, struct compressed_bio *cb = bio->bi_private; u8 *cb_sum = cb->sums; - if (inode->flags & BTRFS_INODE_NODATASUM) + if (!fs_info->csum_root || + inode->flags & BTRFS_INODE_NODATASUM) return 0; shash->tfm = fs_info->csum_shash; diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index aac3d6f4e35b..fb3cfd0aaf1e 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1295,6 +1295,7 @@ static inline u32 BTRFS_MAX_XATTR_SIZE(const struct btrfs_fs_info *info) #define BTRFS_MOUNT_NOLOGREPLAY (1 << 27) #define BTRFS_MOUNT_REF_VERIFY (1 << 28) #define BTRFS_MOUNT_DISCARD_ASYNC (1 << 29) +#define BTRFS_MOUNT_IGNOREBADROOTS (1 << 30) #define BTRFS_DEFAULT_COMMIT_INTERVAL (30) #define BTRFS_DEFAULT_MAX_INLINE (2048) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3d39f5d47ad3..5deedfb0e5c7 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2247,30 +2247,39 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info) root = btrfs_read_tree_root(tree_root, &location); if (IS_ERR(root)) { - ret = PTR_ERR(root); - goto out; + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) { + ret = PTR_ERR(root); + goto out; + } + } else { + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); + fs_info->extent_root = root; } - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); - fs_info->extent_root = root; location.objectid = BTRFS_DEV_TREE_OBJECTID; root = btrfs_read_tree_root(tree_root, &location); if (IS_ERR(root)) { - ret = PTR_ERR(root); - goto out; + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) { + ret = PTR_ERR(root); + goto out; + } + } else { + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); + fs_info->dev_root = root; + btrfs_init_devices_late(fs_info); } - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); - fs_info->dev_root = root; - btrfs_init_devices_late(fs_info); location.objectid = BTRFS_CSUM_TREE_OBJECTID; root = btrfs_read_tree_root(tree_root, &location); if (IS_ERR(root)) { - ret = PTR_ERR(root); - goto out; + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) { + ret = PTR_ERR(root); + goto out; + } + } else { + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); + fs_info->csum_root = root; } - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); - fs_info->csum_root = root; /* * This tree can share blocks with some other fs tree during relocation @@ -2279,11 +2288,14 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info) root = btrfs_get_fs_root(tree_root->fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID, true); if (IS_ERR(root)) { - ret = PTR_ERR(root); - goto out; + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) { + ret = PTR_ERR(root); + goto out; + } + } else { + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); + fs_info->data_reloc_root = root; } - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); - fs_info->data_reloc_root = root; location.objectid = BTRFS_QUOTA_TREE_OBJECTID; root = btrfs_read_tree_root(tree_root, &location); @@ -2296,9 +2308,11 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info) location.objectid = BTRFS_UUID_TREE_OBJECTID; root = btrfs_read_tree_root(tree_root, &location); if (IS_ERR(root)) { - ret = PTR_ERR(root); - if (ret != -ENOENT) - goto out; + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) { + ret = PTR_ERR(root); + if (ret != -ENOENT) + goto out; + } } else { set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); fs_info->uuid_root = root; @@ -2308,11 +2322,14 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info) location.objectid = BTRFS_FREE_SPACE_TREE_OBJECTID; root = btrfs_read_tree_root(tree_root, &location); if (IS_ERR(root)) { - ret = PTR_ERR(root); - goto out; + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) { + ret = PTR_ERR(root); + goto out; + } + } else { + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); + fs_info->free_space_root = root; } - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state); - fs_info->free_space_root = root; } return 0; diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c index 8083d71d6af6..90c728652033 100644 --- a/fs/btrfs/file-item.c +++ b/fs/btrfs/file-item.c @@ -272,7 +272,8 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, int count = 0; u16 csum_size = btrfs_super_csum_size(fs_info->super_copy); - if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) + if (!fs_info->csum_root || + BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) return BLK_STS_OK; path = btrfs_alloc_path(); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index d262944c4297..27752c66dec4 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2187,7 +2187,8 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio, int skip_sum; int async = !atomic_read(&BTRFS_I(inode)->sync_writers); - skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM; + skip_sum = (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) || + !fs_info->csum_root; if (btrfs_is_free_space_inode(BTRFS_I(inode))) metadata = BTRFS_WQ_ENDIO_FREE_SPACE; @@ -2844,6 +2845,9 @@ int btrfs_verify_data_csum(struct btrfs_io_bio *io_bio, u64 phy_offset, if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) return 0; + if (!root->fs_info->csum_root) + return 0; + if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID && test_range_bit(io_tree, start, end, EXTENT_NODATASUM, 1, NULL)) { clear_extent_bits(io_tree, start, end, EXTENT_NODATASUM); diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index f99e89ec46b2..7cc7a9233f5e 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -360,6 +360,7 @@ enum { Opt_rescue, Opt_usebackuproot, Opt_nologreplay, + Opt_ignorebadroots, /* Deprecated options */ Opt_recovery, @@ -455,6 +456,7 @@ static const match_table_t tokens = { static const match_table_t rescue_tokens = { {Opt_usebackuproot, "usebackuproot"}, {Opt_nologreplay, "nologreplay"}, + {Opt_ignorebadroots, "ignorebadroots"}, {Opt_err, NULL}, }; @@ -498,6 +500,10 @@ static int parse_rescue_options(struct btrfs_fs_info *info, const char *options) btrfs_set_and_info(info, NOLOGREPLAY, "disabling log replay at mount time"); break; + case Opt_ignorebadroots: + btrfs_set_and_info(info, IGNOREBADROOTS, + "ignoring bad roots"); + break; case Opt_err: btrfs_info(info, "unrecognized rescue option '%s'", p); ret = -EINVAL; @@ -983,7 +989,8 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, if (new_flags & SB_RDONLY) goto out; - if (check_ro_option(info, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay")) + if (check_ro_option(info, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay") || + check_ro_option(info, BTRFS_MOUNT_IGNOREBADROOTS, "ignorebadroots")) ret = -EINVAL; out: if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) && @@ -1430,6 +1437,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry) seq_puts(seq, ",notreelog"); if (btrfs_test_opt(info, NOLOGREPLAY)) seq_puts(seq, ",rescue=nologreplay"); + if (btrfs_test_opt(info, IGNOREBADROOTS)) + seq_puts(seq, ",rescue=ignorebadroots"); if (btrfs_test_opt(info, FLUSHONCOMMIT)) seq_puts(seq, ",flushoncommit"); if (btrfs_test_opt(info, DISCARD_SYNC)) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 46f4efd58652..f0e6f43a4166 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -7656,6 +7656,19 @@ int btrfs_verify_dev_extents(struct btrfs_fs_info *fs_info) u64 prev_dev_ext_end = 0; int ret = 0; + /* + * We don't have a dev_root because we mounted with ignorebadroots and + * failed to load the root, so we want to skip the verification in this + * case for sure. + * + * However if the dev root is fine, but the tree itself is corrupt we'd + * still fail to mount. This verification is only to make sure writes + * can happen safely, so instead just bypass this check completely in + * the case of IGNOREBADROOTS. + */ + if (btrfs_test_opt(fs_info, IGNOREBADROOTS)) + return 0; + key.objectid = 1; key.type = BTRFS_DEV_EXTENT_KEY; key.offset = 0;