1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (C) 2007 Oracle. All rights reserved.
4 */
5
6 #ifndef BTRFS_TRANSACTION_H
7 #define BTRFS_TRANSACTION_H
8
9 #include <linux/atomic.h>
10 #include <linux/build_bug.h>
11 #include <linux/refcount.h>
12 #include <linux/list.h>
13 #include <linux/time64.h>
14 #include <linux/mutex.h>
15 #include <linux/wait.h>
16 #include "btrfs_inode.h"
17 #include "delayed-ref.h"
18
19 struct dentry;
20 struct inode;
21 struct btrfs_pending_snapshot;
22 struct btrfs_fs_info;
23 struct btrfs_root_item;
24 struct btrfs_root;
25 struct btrfs_path;
26 struct extent_buffer;
27
28 /*
29 * Signal that a direct IO write is in progress, to avoid deadlock for sync
30 * direct IO writes when fsync is called during the direct IO write path.
31 */
32 #define BTRFS_TRANS_DIO_WRITE_STUB ((void *) 1)
33
34 /* Radix-tree tag for roots that are part of the transaction. */
35 #define BTRFS_ROOT_TRANS_TAG 0
36
37 enum btrfs_trans_state {
38 TRANS_STATE_RUNNING,
39 TRANS_STATE_COMMIT_PREP,
40 TRANS_STATE_COMMIT_START,
41 TRANS_STATE_COMMIT_DOING,
42 TRANS_STATE_UNBLOCKED,
43 TRANS_STATE_SUPER_COMMITTED,
44 TRANS_STATE_COMPLETED,
45 TRANS_STATE_MAX,
46 };
47
48 #define BTRFS_TRANS_HAVE_FREE_BGS 0
49 #define BTRFS_TRANS_DIRTY_BG_RUN 1
50 #define BTRFS_TRANS_CACHE_ENOSPC 2
51
52 struct btrfs_transaction {
53 u64 transid;
54 /*
55 * total external writers(USERSPACE/START/ATTACH) in this
56 * transaction, it must be zero before the transaction is
57 * being committed
58 */
59 atomic_t num_extwriters;
60 /*
61 * total writers in this transaction, it must be zero before the
62 * transaction can end
63 */
64 atomic_t num_writers;
65 refcount_t use_count;
66
67 unsigned long flags;
68
69 /* Be protected by fs_info->trans_lock when we want to change it. */
70 enum btrfs_trans_state state;
71 int aborted;
72 struct list_head list;
73 struct extent_io_tree dirty_pages;
74 time64_t start_time;
75 wait_queue_head_t writer_wait;
76 wait_queue_head_t commit_wait;
77 struct list_head pending_snapshots;
78 struct list_head dev_update_list;
79 struct list_head switch_commits;
80 struct list_head dirty_bgs;
81
82 /*
83 * There is no explicit lock which protects io_bgs, rather its
84 * consistency is implied by the fact that all the sites which modify
85 * it do so under some form of transaction critical section, namely:
86 *
87 * - btrfs_start_dirty_block_groups - This function can only ever be
88 * run by one of the transaction committers. Refer to
89 * BTRFS_TRANS_DIRTY_BG_RUN usage in btrfs_commit_transaction
90 *
91 * - btrfs_write_dirty_blockgroups - this is called by
92 * commit_cowonly_roots from transaction critical section
93 * (TRANS_STATE_COMMIT_DOING)
94 *
95 * - btrfs_cleanup_dirty_bgs - called on transaction abort
96 */
97 struct list_head io_bgs;
98 struct list_head dropped_roots;
99 struct extent_io_tree pinned_extents;
100
101 /*
102 * we need to make sure block group deletion doesn't race with
103 * free space cache writeout. This mutex keeps them from stomping
104 * on each other
105 */
106 struct mutex cache_write_mutex;
107 spinlock_t dirty_bgs_lock;
108 /* Protected by spin lock fs_info->unused_bgs_lock. */
109 struct list_head deleted_bgs;
110 spinlock_t dropped_roots_lock;
111 struct btrfs_delayed_ref_root delayed_refs;
112 struct btrfs_fs_info *fs_info;
113
114 /*
115 * Number of ordered extents the transaction must wait for before
116 * committing. These are ordered extents started by a fast fsync.
117 */
118 atomic_t pending_ordered;
119 wait_queue_head_t pending_wait;
120 };
121
122 enum {
123 ENUM_BIT(__TRANS_FREEZABLE),
124 ENUM_BIT(__TRANS_START),
125 ENUM_BIT(__TRANS_ATTACH),
126 ENUM_BIT(__TRANS_JOIN),
127 ENUM_BIT(__TRANS_JOIN_NOLOCK),
128 ENUM_BIT(__TRANS_DUMMY),
129 ENUM_BIT(__TRANS_JOIN_NOSTART),
130 };
131
132 #define TRANS_START (__TRANS_START | __TRANS_FREEZABLE)
133 #define TRANS_ATTACH (__TRANS_ATTACH)
134 #define TRANS_JOIN (__TRANS_JOIN | __TRANS_FREEZABLE)
135 #define TRANS_JOIN_NOLOCK (__TRANS_JOIN_NOLOCK)
136 #define TRANS_JOIN_NOSTART (__TRANS_JOIN_NOSTART)
137
138 #define TRANS_EXTWRITERS (__TRANS_START | __TRANS_ATTACH)
139
140 /*
141 * Number of extent buffers a transaction handle tracks for writeback
142 * inhibition. The CLOCK reference bits pack into a u32 so this must not exceed
143 * 32, and keeping it a power of two lets the compiler reduce the CLOCK hand
144 * modulo to a mask.
145 */
146 #define BTRFS_INHIBITED_EBS_SLOTS 8
147
148 static_assert(BTRFS_INHIBITED_EBS_SLOTS <= 32);
149 static_assert(BTRFS_INHIBITED_EBS_SLOTS != 0 &&
150 (BTRFS_INHIBITED_EBS_SLOTS & (BTRFS_INHIBITED_EBS_SLOTS - 1)) == 0);
151
152 struct btrfs_trans_handle {
153 u64 transid;
154 u64 bytes_reserved;
155 u64 delayed_refs_bytes_reserved;
156 u64 chunk_bytes_reserved;
157 unsigned long delayed_ref_updates;
158 unsigned long delayed_ref_csum_deletions;
159 struct btrfs_transaction *transaction;
160 struct btrfs_block_rsv *block_rsv;
161 struct btrfs_block_rsv *orig_rsv;
162 /* Set by a task that wants to create a snapshot. */
163 struct btrfs_pending_snapshot *pending_snapshot;
164 refcount_t use_count;
165 unsigned int type;
166 /*
167 * Error code of transaction abort, set outside of locks and must use
168 * the READ_ONCE/WRITE_ONCE access
169 */
170 short aborted;
171 bool adding_csums;
172 bool allocating_chunk;
173 bool removing_chunk;
174 bool reloc_reserved;
175 bool in_fsync;
176 struct btrfs_fs_info *fs_info;
177 struct list_head new_bgs;
178 struct btrfs_block_rsv delayed_rsv;
179
180 /* Extent buffers this handle has inhibited writeback on. */
181 struct extent_buffer *inhibited_ebs[BTRFS_INHIBITED_EBS_SLOTS];
182 /* CLOCK reference bit per slot. */
183 u32 inhibited_ebs_referenced;
184 u32 nr_inhibited_ebs;
185 /* CLOCK hand. */
186 u32 inhibited_ebs_hand;
187 };
188
189 /*
190 * The abort status can be changed between calls and is not protected by locks.
191 * This accepts btrfs_transaction and btrfs_trans_handle as types. Once it's
192 * set to a non-zero value it does not change, so the macro should be in checks
193 * but is not necessary for further reads of the value.
194 */
195 #define TRANS_ABORTED(trans) (unlikely(READ_ONCE((trans)->aborted)))
196
197 struct btrfs_pending_snapshot {
198 struct dentry *dentry;
199 struct btrfs_inode *dir;
200 struct btrfs_root *root;
201 struct btrfs_root_item *root_item;
202 struct btrfs_root *snap;
203 struct btrfs_qgroup_inherit *inherit;
204 struct btrfs_path *path;
205 /* block reservation for the operation */
206 struct btrfs_block_rsv block_rsv;
207 /* extra metadata reservation for relocation */
208 int error;
209 /* Preallocated anonymous block device number */
210 dev_t anon_dev;
211 bool readonly;
212 struct list_head list;
213 };
214
btrfs_set_inode_last_trans(struct btrfs_trans_handle * trans,struct btrfs_inode * inode)215 static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
216 struct btrfs_inode *inode)
217 {
218 spin_lock(&inode->lock);
219 inode->last_trans = trans->transaction->transid;
220 inode->last_sub_trans = btrfs_get_root_log_transid(inode->root);
221 inode->last_log_commit = inode->last_sub_trans - 1;
222 spin_unlock(&inode->lock);
223 }
224
225 /*
226 * Make qgroup codes to skip given qgroupid, means the old/new_roots for
227 * qgroup won't contain the qgroupid in it.
228 */
btrfs_set_skip_qgroup(struct btrfs_trans_handle * trans,u64 qgroupid)229 static inline void btrfs_set_skip_qgroup(struct btrfs_trans_handle *trans,
230 u64 qgroupid)
231 {
232 struct btrfs_delayed_ref_root *delayed_refs;
233
234 delayed_refs = &trans->transaction->delayed_refs;
235 WARN_ON(delayed_refs->qgroup_to_skip);
236 delayed_refs->qgroup_to_skip = qgroupid;
237 }
238
btrfs_clear_skip_qgroup(struct btrfs_trans_handle * trans)239 static inline void btrfs_clear_skip_qgroup(struct btrfs_trans_handle *trans)
240 {
241 struct btrfs_delayed_ref_root *delayed_refs;
242
243 delayed_refs = &trans->transaction->delayed_refs;
244 WARN_ON(!delayed_refs->qgroup_to_skip);
245 delayed_refs->qgroup_to_skip = 0;
246 }
247
248 /*
249 * We want the transaction abort to print stack trace only for errors where the
250 * cause could be a bug, eg. due to ENOSPC, and not for common errors that are
251 * caused by external factors.
252 */
btrfs_abort_should_print_stack(int error)253 static inline bool btrfs_abort_should_print_stack(int error)
254 {
255 switch (error) {
256 case -EIO:
257 case -EROFS:
258 case -ENOMEM:
259 return false;
260 }
261 return true;
262 }
263
264 /*
265 * Compile-time and run-time verification of error passed to transaction abort.
266 * Direct constants will be caught at compile time, errors read from variables
267 * can be caught only at run-time and will warn under debugging config.
268 *
269 * How verification works:
270 * - accepted builtin constants are all -EIO and such
271 * - for compile-time check, invalid condition produces a negative-sized array
272 * type, valid zero-sized
273 * - when a variable is passed as error the first check is a no-op
274 * - with enabled debugging, the second array type size is constructed from the
275 * real variable value, valid condition produces array of size 1
276 * - sizeof(type) does not generate any code
277 */
278 #define VERIFY_NEGATIVE_ERROR(error) \
279 do { \
280 (void)sizeof(char[-!(__builtin_constant_p(error) ? (error) < 0 : 1)]); \
281 if (IS_ENABLED(CONFIG_BTRFS_DEBUG)) { \
282 if (sizeof(char[(error) < 0]) != 1) \
283 DEBUG_WARN("error >= 0 passed to btrfs_abort_transaction()"); \
284 } \
285 } while(0)
286
287 /*
288 * Call btrfs_abort_transaction() as early as possible when an error condition
289 * is detected, that way the exact stack trace is reported for some errors.
290 *
291 * Error number must be negative as it encodes wheather it's the first abort.
292 */
293 #define btrfs_abort_transaction(trans, error) \
294 do { \
295 int __error = (error); \
296 \
297 VERIFY_NEGATIVE_ERROR(error); \
298 /* Report first abort since mount */ \
299 if (!test_and_set_bit(BTRFS_FS_STATE_TRANS_ABORTED, \
300 &((trans)->fs_info->fs_state))) { \
301 WARN_ON(btrfs_abort_should_print_stack(__error)); \
302 __error = -__error; \
303 } \
304 __btrfs_abort_transaction((trans), __func__, \
305 __LINE__, __error); \
306 } while (0)
307
308 int btrfs_end_transaction(struct btrfs_trans_handle *trans);
309 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
310 unsigned int num_items);
311 struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
312 struct btrfs_root *root,
313 unsigned int num_items);
314 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root);
315 struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root);
316 struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root);
317 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root);
318 struct btrfs_trans_handle *btrfs_attach_transaction_barrier(
319 struct btrfs_root *root);
320 int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid);
321
322 void btrfs_add_dead_root(struct btrfs_root *root);
323 void btrfs_maybe_wake_unfinished_drop(struct btrfs_fs_info *fs_info);
324 int btrfs_clean_one_deleted_snapshot(struct btrfs_fs_info *fs_info);
325 int btrfs_commit_transaction(struct btrfs_trans_handle *trans);
326 void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans);
327 int btrfs_commit_current_transaction(struct btrfs_root *root);
328 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans);
329 bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans);
330 void btrfs_throttle(struct btrfs_fs_info *fs_info);
331 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
332 struct btrfs_root *root);
333 int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
334 struct extent_io_tree *dirty_pages, int mark);
335 int btrfs_wait_tree_log_extents(struct btrfs_root *root, int mark);
336 int btrfs_transaction_blocked(struct btrfs_fs_info *info);
337 void btrfs_put_transaction(struct btrfs_transaction *transaction);
338 void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
339 struct btrfs_root *root);
340 void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans);
341 void __cold __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
342 const char *function,
343 unsigned int line, int error);
344
345 int __init btrfs_transaction_init(void);
346 void __cold btrfs_transaction_exit(void);
347
348 #endif
349