Btrfs has an optimization where it will preallocate dentries during readdir to fill in enough information to open the inode without an extra lookup. But, we're calling d_alloc, which is doing GFP_KERNEL allocations, and that leads to deadlocks because our readdir code has tree locks held. For now, disable this optimization. We'll fix the gfp mask in the next merge window.
Unified · Split
| @@ -4192,7 +4192,6 @@ static int btrfs_real_readdir(struct file *filp, void *dirent, · 4191 unmodified lines | ||
| 4192 | 4192 | struct btrfs_path *path; |
| 4193 | 4193 | struct list_head ins_list; |
| 4194 | 4194 | struct list_head del_list; |
| 4195 | − struct qstr q; | |
| 4196 | 4195 | int ret; |
| 4197 | 4196 | struct extent_buffer *leaf; |
| 4198 | 4197 | int slot; |
| @@ -4283,7 +4282,6 @@ static int btrfs_real_readdir(struct file *filp, void *dirent, · 84 unmodified lines | ||
| 4283 | 4282 | |
| 4284 | 4283 | while (di_cur < di_total) { |
| 4285 | 4284 | struct btrfs_key location; |
| 4286 | − struct dentry *tmp; | |
| 4287 | 4285 | |
| 4288 | 4286 | if (verify_dir_item(root, leaf, di)) |
| 4289 | 4287 | break; |
| @@ -4304,33 +4302,7 @@ static int btrfs_real_readdir(struct file *filp, void *dirent, · 14 unmodified lines | ||
| 4304 | 4302 | d_type = btrfs_filetype_table[btrfs_dir_type(leaf, di)]; |
| 4305 | 4303 | btrfs_dir_item_key_to_cpu(leaf, di, &location); |
| 4306 | 4304 | |
| 4307 | − q.name = name_ptr; | |
| 4308 | − q.len = name_len; | |
| 4309 | − q.hash = full_name_hash(q.name, q.len); | |
| 4310 | − tmp = d_lookup(filp->f_dentry, &q); | |
| 4311 | − if (!tmp) { | |
| 4312 | − struct btrfs_key *newkey; | |
| 4313 | − | |
| 4314 | − newkey = kzalloc(sizeof(struct btrfs_key), | |
| 4315 | − GFP_NOFS); | |
| 4316 | − if (!newkey) | |
| 4317 | − goto no_dentry; | |
| 4318 | − tmp = d_alloc(filp->f_dentry, &q); | |
| 4319 | − if (!tmp) { | |
| 4320 | − kfree(newkey); | |
| 4321 | − dput(tmp); | |
| 4322 | − goto no_dentry; | |
| 4323 | − } | |
| 4324 | − memcpy(newkey, &location, | |
| 4325 | − sizeof(struct btrfs_key)); | |
| 4326 | − tmp->d_fsdata = newkey; | |
| 4327 | − tmp->d_flags |= DCACHE_NEED_LOOKUP; | |
| 4328 | − d_rehash(tmp); | |
| 4329 | − dput(tmp); | |
| 4330 | − } else { | |
| 4331 | − dput(tmp); | |
| 4332 | − } | |
| 4333 | −no_dentry: | |
| 4305 | + | |
| 4334 | 4306 | /* is this a reference to our own snapshot? If so |
| 4335 | 4307 | * skip it. |
| 4336 | 4308 | * |