btrfs: add support for processing pending changes

There are some actions that modify global filesystem state but cannot be performed at the time of request, but later at the transaction commit time when the filesystem is in a known state. For example enabling new incompat features on-the-fly or issuing transaction commit from unsafe contexts (sysfs handlers). Signed-off-by: David Sterba <dsterba@suse.cz>

btrfs: add support for processing pending changes
There are some actions that modify global filesystem state but cannot be performed at the time of request, but later at the transaction commit time when the filesystem is in a known state. For example enabling new incompat features on-the-fly or issuing transaction commit from unsafe contexts (sysfs handlers). Signed-off-by: David Sterba <dsterba@suse.cz>
David Sterba
1 parent 206c5f60a3
Showing 4 changed files with 69 additions and 0 deletions Side-by-side Diff
fs/btrfs/ctree.h
fs/btrfs/disk-io.c
fs/btrfs/transaction.c
fs/btrfs/transaction.h
@@ -1402,6 +1402,11 @@
 	 */
 	u64 last_trans_log_full_commit;
 	unsigned long mount_opt;
+	/*
+	 * Track requests for actions that need to be done during transaction
+	 * commit (like for some mount options).
+	 */
+	unsigned long pending_changes;
 	unsigned long compress_type:4;
 	int commit_interval;
 	/*
@@ -2103,6 +2108,7 @@
 #define btrfs_raw_test_opt(o, opt)	((o) & BTRFS_MOUNT_##opt)
 #define btrfs_test_opt(root, opt)	((root)->fs_info->mount_opt & \
 					 BTRFS_MOUNT_##opt)
+
 #define btrfs_set_and_info(root, opt, fmt, args...)			\
 {									\
 	if (!btrfs_test_opt(root, opt))					\
@@ -2116,6 +2122,45 @@
 		btrfs_info(root->fs_info, fmt, ##args);			\
 	btrfs_clear_opt(root->fs_info->mount_opt, opt);			\
 }
+
+/*
+ * Requests for changes that need to be done during transaction commit.
+ *
+ * Internal mount options that are used for special handling of the real
+ * mount options (eg. cannot be set during remount and have to be set during
+ * transaction commit)
+ */
+
+#define btrfs_test_pending(info, opt)	\
+	test_bit(BTRFS_PENDING_##opt, &(info)->pending_changes)
+#define btrfs_set_pending(info, opt)	\
+	set_bit(BTRFS_PENDING_##opt, &(info)->pending_changes)
+#define btrfs_clear_pending(info, opt)	\
+	clear_bit(BTRFS_PENDING_##opt, &(info)->pending_changes)
+
+/*
+ * Helpers for setting pending mount option changes.
+ *
+ * Expects corresponding macros
+ * BTRFS_PENDING_SET_ and CLEAR_ + short mount option name
+ */
+#define btrfs_set_pending_and_info(info, opt, fmt, args...)            \
+do {                                                                   \
+       if (!btrfs_raw_test_opt((info)->mount_opt, opt)) {              \
+               btrfs_info((info), fmt, ##args);                        \
+               btrfs_set_pending((info), SET_##opt);                   \
+               btrfs_clear_pending((info), CLEAR_##opt);               \
+       }                                                               \
+} while(0)
+
+#define btrfs_clear_pending_and_info(info, opt, fmt, args...)          \
+do {                                                                   \
+       if (btrfs_raw_test_opt((info)->mount_opt, opt)) {               \
+               btrfs_info((info), fmt, ##args);                        \
+               btrfs_set_pending((info), CLEAR_##opt);                 \
+               btrfs_clear_pending((info), SET_##opt);                 \
+       }                                                               \
+} while(0)
  
 /*
  * Inode flags
@@ -2834,6 +2834,12 @@
 	if (btrfs_test_opt(tree_root, CHANGE_INODE_CACHE))
 		btrfs_set_opt(tree_root->fs_info->mount_opt, INODE_MAP_CACHE);
  
+	/*
+	 * Mount does not set all options immediatelly, we can do it now and do
+	 * not have to wait for transaction commit
+	 */
+	btrfs_apply_pending_changes(fs_info);
+
 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 	if (btrfs_test_opt(tree_root, CHECK_INTEGRITY)) {
 		ret = btrfsic_mount(tree_root, fs_devices,
@@ -1850,6 +1850,8 @@
 	else
 		btrfs_clear_opt(root->fs_info->mount_opt, INODE_MAP_CACHE);
  
+	btrfs_apply_pending_changes(root->fs_info);
+
 	/* commit_fs_roots gets rid of all the tree log roots, it is now
 	 * safe to free the root of tree log roots
 	 */
@@ -2018,5 +2020,19 @@
 		ret = btrfs_drop_snapshot(root, NULL, 1, 0);
  
 	return (ret < 0) ? 0 : 1;
+}
+
+void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
+{
+	unsigned long prev;
+	unsigned long bit;
+
+	prev = cmpxchg(&fs_info->pending_changes, 0, 0);
+	if (!prev)
+		return;
+
+	if (prev)
+		btrfs_warn(fs_info,
+			"unknown pending changes left 0x%lx, ignoring", prev);
 }
@@ -170,5 +170,7 @@
 int btrfs_transaction_blocked(struct btrfs_fs_info *info);
 int btrfs_transaction_in_commit(struct btrfs_fs_info *info);
 void btrfs_put_transaction(struct btrfs_transaction *transaction);
+void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info);
+
 #endif
...	...	@@ -1402,6 +1402,11 @@
1402	1402	*/
1403	1403	u64 last_trans_log_full_commit;
1404	1404	unsigned long mount_opt;
	1405	+ /*
	1406	+ * Track requests for actions that need to be done during transaction
	1407	+ * commit (like for some mount options).
	1408	+ */
	1409	+ unsigned long pending_changes;
1405	1410	unsigned long compress_type:4;
1406	1411	int commit_interval;
1407	1412	/*
...	...	@@ -2103,6 +2108,7 @@
2103	2108	#define btrfs_raw_test_opt(o, opt) ((o) & BTRFS_MOUNT_##opt)
2104	2109	#define btrfs_test_opt(root, opt) ((root)->fs_info->mount_opt & \
2105	2110	BTRFS_MOUNT_##opt)
	2111	+
2106	2112	#define btrfs_set_and_info(root, opt, fmt, args...) \
2107	2113	{ \
2108	2114	if (!btrfs_test_opt(root, opt)) \
...	...	@@ -2116,6 +2122,45 @@
2116	2122	btrfs_info(root->fs_info, fmt, ##args); \
2117	2123	btrfs_clear_opt(root->fs_info->mount_opt, opt); \
2118	2124	}
	2125	+
	2126	+/*
	2127	+ * Requests for changes that need to be done during transaction commit.
	2128	+ *
	2129	+ * Internal mount options that are used for special handling of the real
	2130	+ * mount options (eg. cannot be set during remount and have to be set during
	2131	+ * transaction commit)
	2132	+ */
	2133	+
	2134	+#define btrfs_test_pending(info, opt) \
	2135	+ test_bit(BTRFS_PENDING_##opt, &(info)->pending_changes)
	2136	+#define btrfs_set_pending(info, opt) \
	2137	+ set_bit(BTRFS_PENDING_##opt, &(info)->pending_changes)
	2138	+#define btrfs_clear_pending(info, opt) \
	2139	+ clear_bit(BTRFS_PENDING_##opt, &(info)->pending_changes)
	2140	+
	2141	+/*
	2142	+ * Helpers for setting pending mount option changes.
	2143	+ *
	2144	+ * Expects corresponding macros
	2145	+ * BTRFS_PENDING_SET_ and CLEAR_ + short mount option name
	2146	+ */
	2147	+#define btrfs_set_pending_and_info(info, opt, fmt, args...) \
	2148	+do { \
	2149	+ if (!btrfs_raw_test_opt((info)->mount_opt, opt)) { \
	2150	+ btrfs_info((info), fmt, ##args); \
	2151	+ btrfs_set_pending((info), SET_##opt); \
	2152	+ btrfs_clear_pending((info), CLEAR_##opt); \
	2153	+ } \
	2154	+} while(0)
	2155	+
	2156	+#define btrfs_clear_pending_and_info(info, opt, fmt, args...) \
	2157	+do { \
	2158	+ if (btrfs_raw_test_opt((info)->mount_opt, opt)) { \
	2159	+ btrfs_info((info), fmt, ##args); \
	2160	+ btrfs_set_pending((info), CLEAR_##opt); \
	2161	+ btrfs_clear_pending((info), SET_##opt); \
	2162	+ } \
	2163	+} while(0)
2119	2164
2120	2165	/*
2121	2166	* Inode flags
...	...	@@ -2834,6 +2834,12 @@
2834	2834	if (btrfs_test_opt(tree_root, CHANGE_INODE_CACHE))
2835	2835	btrfs_set_opt(tree_root->fs_info->mount_opt, INODE_MAP_CACHE);
2836	2836
	2837	+ /*
	2838	+ * Mount does not set all options immediatelly, we can do it now and do
	2839	+ * not have to wait for transaction commit
	2840	+ */
	2841	+ btrfs_apply_pending_changes(fs_info);
	2842	+
2837	2843	#ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2838	2844	if (btrfs_test_opt(tree_root, CHECK_INTEGRITY)) {
2839	2845	ret = btrfsic_mount(tree_root, fs_devices,
...	...	@@ -1850,6 +1850,8 @@
1850	1850	else
1851	1851	btrfs_clear_opt(root->fs_info->mount_opt, INODE_MAP_CACHE);
1852	1852
	1853	+ btrfs_apply_pending_changes(root->fs_info);
	1854	+
1853	1855	/* commit_fs_roots gets rid of all the tree log roots, it is now
1854	1856	* safe to free the root of tree log roots
1855	1857	*/
...	...	@@ -2018,5 +2020,19 @@
2018	2020	ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2019	2021
2020	2022	return (ret < 0) ? 0 : 1;
	2023	+}
	2024	+
	2025	+void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
	2026	+{
	2027	+ unsigned long prev;
	2028	+ unsigned long bit;
	2029	+
	2030	+ prev = cmpxchg(&fs_info->pending_changes, 0, 0);
	2031	+ if (!prev)
	2032	+ return;
	2033	+
	2034	+ if (prev)
	2035	+ btrfs_warn(fs_info,
	2036	+ "unknown pending changes left 0x%lx, ignoring", prev);
2021	2037	}
...	...	@@ -170,5 +170,7 @@
170	170	int btrfs_transaction_blocked(struct btrfs_fs_info *info);
171	171	int btrfs_transaction_in_commit(struct btrfs_fs_info *info);
172	172	void btrfs_put_transaction(struct btrfs_transaction *transaction);
	173	+void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info);
	174	+
173	175	#endif