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| author | ethanwu <ethanwu@synology.com> | 2018-04-29 15:59:42 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-05-02 11:54:58 +0200 |
| commit | 998ac6d21cfd6efd58f5edf420bae8839dda9f2a (patch) | |
| tree | 488d8767d0d027b387876bfd3a7da78c6d90f761 | |
| parent | 17515f1b764df36271f3166c714f5a78301fbaa7 (diff) | |
| download | linux-998ac6d21cfd6efd58f5edf420bae8839dda9f2a.tar.bz2 | |
btrfs: Take trans lock before access running trans in check_delayed_ref
In preivous patch:
Btrfs: kill trans in run_delalloc_nocow and btrfs_cross_ref_exist
We avoid starting btrfs transaction and get this information from
fs_info->running_transaction directly.
When accessing running_transaction in check_delayed_ref, there's a
chance that current transaction will be freed by commit transaction
after the NULL pointer check of running_transaction is passed.
After looking all the other places using fs_info->running_transaction,
they are either protected by trans_lock or holding the transactions.
Fix this by using trans_lock and increasing the use_count.
Fixes: e4c3b2dcd144 ("Btrfs: kill trans in run_delalloc_nocow and btrfs_cross_ref_exist")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: ethanwu <ethanwu@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
| -rw-r--r-- | fs/btrfs/extent-tree.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index f99102063366..3871658b6ab1 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3142,7 +3142,11 @@ static noinline int check_delayed_ref(struct btrfs_root *root, struct rb_node *node; int ret = 0; + spin_lock(&root->fs_info->trans_lock); cur_trans = root->fs_info->running_transaction; + if (cur_trans) + refcount_inc(&cur_trans->use_count); + spin_unlock(&root->fs_info->trans_lock); if (!cur_trans) return 0; @@ -3151,6 +3155,7 @@ static noinline int check_delayed_ref(struct btrfs_root *root, head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); if (!head) { spin_unlock(&delayed_refs->lock); + btrfs_put_transaction(cur_trans); return 0; } @@ -3167,6 +3172,7 @@ static noinline int check_delayed_ref(struct btrfs_root *root, mutex_lock(&head->mutex); mutex_unlock(&head->mutex); btrfs_put_delayed_ref_head(head); + btrfs_put_transaction(cur_trans); return -EAGAIN; } spin_unlock(&delayed_refs->lock); @@ -3199,6 +3205,7 @@ static noinline int check_delayed_ref(struct btrfs_root *root, } spin_unlock(&head->lock); mutex_unlock(&head->mutex); + btrfs_put_transaction(cur_trans); return ret; } |