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btrfs: introduce mount option rescue=ignorebadroots

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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 <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2020-10-16 11:29:18 -04:00 committed by David Sterba
parent 68319c18cb
commit 42437a6386
10 changed files with 130 additions and 28 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

48
fs/btrfs/block-group.c
View file

@ -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 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)) {
struct extent_map *em;
struct map_lookup *map;
struct btrfs_block_group *bg;
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;

8
fs/btrfs/block-rsv.c
View file

@ -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 dereferencing 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;

2
fs/btrfs/compression.c
View file

@ -150,7 +150,7 @@ 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;

1
fs/btrfs/ctree.h
View file

@ -1298,6 +1298,7 @@ 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)

65
fs/btrfs/disk-io.c
View file

@ -2307,30 +2307,39 @@ 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
@ -2339,11 +2348,14 @@ 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);
@ -2356,9 +2368,11 @@ 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;
@ -2368,11 +2382,14 @@ 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;

2
fs/btrfs/file-item.c
View file

@ -272,7 +272,7 @@ 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();

6
fs/btrfs/inode.c
View file

@ -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;
@ -2902,6 +2903,9 @@ 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);

12
fs/btrfs/super.c
View file

@ -360,6 +360,7 @@ enum {
Opt_rescue,
Opt_usebackuproot,
Opt_nologreplay,
Opt_ignorebadroots,
/* Deprecated options */
Opt_recovery,
@ -455,6 +456,8 @@ static const match_table_t tokens = {
static const match_table_t rescue_tokens = {
{Opt_usebackuproot, "usebackuproot"},
{Opt_nologreplay, "nologreplay"},
{Opt_ignorebadroots, "ignorebadroots"},
{Opt_ignorebadroots, "ibadroots"},
{Opt_err, NULL},
};
@ -498,6 +501,10 @@ 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 +990,8 @@ 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) &&
@ -1439,6 +1447,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
print_rescue_option(seq, "nologreplay", &printed);
if (btrfs_test_opt(info, USEBACKUPROOT))
print_rescue_option(seq, "usebackuproot", &printed);
if (btrfs_test_opt(info, IGNOREBADROOTS))
print_rescue_option(seq, "ignorebadroots", &printed);
if (btrfs_test_opt(info, FLUSHONCOMMIT))
seq_puts(seq, ",flushoncommit");
if (btrfs_test_opt(info, DISCARD_SYNC))

1
fs/btrfs/sysfs.c
View file

@ -332,6 +332,7 @@ BTRFS_ATTR(static_feature, send_stream_version, send_stream_version_show);
static const char *rescue_opts[] = {
"usebackuproot",
"nologreplay",
"ignorebadroots",
};
static ssize_t supported_rescue_options_show(struct kobject *kobj,

13
fs/btrfs/volumes.c
View file

@ -7659,6 +7659,19 @@ 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 corrupted
* 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;