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btrfs: qgroup: Fix a race in delayed_ref which leads to abort trans
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Between btrfs_allocerved_file_extent() and
btrfs_add_delayed_qgroup_reserve(), there is a window that delayed_refs
are run and delayed ref head maybe freed before
btrfs_add_delayed_qgroup_reserve().

This will cause btrfs_dad_delayed_qgroup_reserve() to return -ENOENT,
and cause transaction to be aborted.

This patch will record qgroup reserve space info into delayed_ref_head
at btrfs_add_delayed_ref(), to eliminate the race window.

Reported-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
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Qu Wenruo authored and Chris Mason committed Oct 27, 2015
1 parent 6962491 commit 5846a3c
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Showing 5 changed files with 32 additions and 21 deletions.
3 changes: 2 additions & 1 deletion fs/btrfs/ctree.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3430,7 +3430,8 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 root_objectid, u64 owner,
u64 offset, struct btrfs_key *ins);
u64 offset, u64 ram_bytes,
struct btrfs_key *ins);
int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 root_objectid, u64 owner, u64 offset,
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22 changes: 17 additions & 5 deletions fs/btrfs/delayed-ref.c
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Original file line number Diff line number Diff line change
Expand Up @@ -535,7 +535,8 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info,
struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_node *ref,
struct btrfs_qgroup_extent_record *qrecord,
u64 bytenr, u64 num_bytes, int action, int is_data)
u64 bytenr, u64 num_bytes, u64 ref_root, u64 reserved,
int action, int is_data)
{
struct btrfs_delayed_ref_head *existing;
struct btrfs_delayed_ref_head *head_ref = NULL;
Expand All @@ -544,6 +545,9 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info,
int count_mod = 1;
int must_insert_reserved = 0;

/* If reserved is provided, it must be a data extent. */
BUG_ON(!is_data && reserved);

/*
* the head node stores the sum of all the mods, so dropping a ref
* should drop the sum in the head node by one.
Expand Down Expand Up @@ -593,6 +597,11 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info,

/* Record qgroup extent info if provided */
if (qrecord) {
if (ref_root && reserved) {
head_ref->qgroup_ref_root = ref_root;
head_ref->qgroup_reserved = reserved;
}

qrecord->bytenr = bytenr;
qrecord->num_bytes = num_bytes;
qrecord->old_roots = NULL;
Expand All @@ -611,6 +620,8 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info,
existing = htree_insert(&delayed_refs->href_root,
&head_ref->href_node);
if (existing) {
WARN_ON(ref_root && reserved && existing->qgroup_ref_root
&& existing->qgroup_reserved);
update_existing_head_ref(delayed_refs, &existing->node, ref);
/*
* we've updated the existing ref, free the newly
Expand Down Expand Up @@ -777,7 +788,7 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
* the spin lock
*/
head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,
bytenr, num_bytes, action, 0);
bytenr, num_bytes, 0, 0, action, 0);

add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,
num_bytes, parent, ref_root, level, action);
Expand All @@ -800,7 +811,7 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes,
u64 parent, u64 ref_root,
u64 owner, u64 offset, int action,
u64 owner, u64 offset, u64 reserved, int action,
struct btrfs_delayed_extent_op *extent_op)
{
struct btrfs_delayed_data_ref *ref;
Expand Down Expand Up @@ -839,7 +850,8 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
* the spin lock
*/
head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,
bytenr, num_bytes, action, 1);
bytenr, num_bytes, ref_root, reserved,
action, 1);

add_delayed_data_ref(fs_info, trans, head_ref, &ref->node, bytenr,
num_bytes, parent, ref_root, owner, offset,
Expand Down Expand Up @@ -894,7 +906,7 @@ int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
spin_lock(&delayed_refs->lock);

add_delayed_ref_head(fs_info, trans, &head_ref->node, NULL, bytenr,
num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
num_bytes, 0, 0, BTRFS_UPDATE_DELAYED_HEAD,
extent_op->is_data);

spin_unlock(&delayed_refs->lock);
Expand Down
2 changes: 1 addition & 1 deletion fs/btrfs/delayed-ref.h
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Original file line number Diff line number Diff line change
Expand Up @@ -248,7 +248,7 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes,
u64 parent, u64 ref_root,
u64 owner, u64 offset, int action,
u64 owner, u64 offset, u64 reserved, int action,
struct btrfs_delayed_extent_op *extent_op);
int btrfs_add_delayed_qgroup_reserve(struct btrfs_fs_info *fs_info,
struct btrfs_trans_handle *trans,
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14 changes: 8 additions & 6 deletions fs/btrfs/extent-tree.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2087,8 +2087,8 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
BTRFS_ADD_DELAYED_REF, NULL);
} else {
ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
num_bytes,
parent, root_objectid, owner, offset,
num_bytes, parent, root_objectid,
owner, offset, 0,
BTRFS_ADD_DELAYED_REF, NULL);
}
return ret;
Expand Down Expand Up @@ -6832,8 +6832,8 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root *root,
ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
num_bytes,
parent, root_objectid, owner,
offset, BTRFS_DROP_DELAYED_REF,
NULL);
offset, 0,
BTRFS_DROP_DELAYED_REF, NULL);
}
return ret;
}
Expand Down Expand Up @@ -7759,7 +7759,8 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 root_objectid, u64 owner,
u64 offset, struct btrfs_key *ins)
u64 offset, u64 ram_bytes,
struct btrfs_key *ins)
{
int ret;

Expand All @@ -7768,7 +7769,8 @@ int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
ret = btrfs_add_delayed_data_ref(root->fs_info, trans, ins->objectid,
ins->offset, 0,
root_objectid, owner, offset,
BTRFS_ADD_DELAYED_EXTENT, NULL);
ram_bytes, BTRFS_ADD_DELAYED_EXTENT,
NULL);
return ret;
}

Expand Down
12 changes: 4 additions & 8 deletions fs/btrfs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2127,17 +2127,13 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
ins.type = BTRFS_EXTENT_ITEM_KEY;
ret = btrfs_alloc_reserved_file_extent(trans, root,
root->root_key.objectid,
btrfs_ino(inode), file_pos, &ins);
if (ret < 0)
goto out;
btrfs_ino(inode), file_pos,
ram_bytes, &ins);
/*
* Release the reserved range from inode dirty range map, and
* move it to delayed ref codes, as now accounting only happens at
* commit_transaction() time.
* Release the reserved range from inode dirty range map, as it is
* already moved into delayed_ref_head
*/
btrfs_qgroup_release_data(inode, file_pos, ram_bytes);
ret = btrfs_add_delayed_qgroup_reserve(root->fs_info, trans,
root->objectid, disk_bytenr, ram_bytes);
out:
btrfs_free_path(path);

Expand Down

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