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authorethanwu <ethanwu@synology.com>2018-04-29 15:59:42 +0800
committerDavid Sterba <dsterba@suse.com>2018-05-02 11:54:58 +0200
commit998ac6d21cfd6efd58f5edf420bae8839dda9f2a (patch)
tree488d8767d0d027b387876bfd3a7da78c6d90f761 /fs
parent17515f1b764df36271f3166c714f5a78301fbaa7 (diff)
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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>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/extent-tree.c7
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;
}