btrfs: track exclusive filesystem operation in flags
There are several operations, usually started from ioctls, that cannot
run concurrently. The status is tracked in
mutually_exclusive_operation_running as an atomic_t. We can easily track
the status as one of the per-filesystem flag bits with same
synchronization guarantees.
The conversion replaces:
* atomic_xchg(..., 1) -> test_and_set_bit(FLAG, ...)
* atomic_set(..., 0) -> clear_bit(FLAG, ...)
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e9d7711..70631d7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -705,6 +705,11 @@
#define BTRFS_FS_BTREE_ERR 11
#define BTRFS_FS_LOG1_ERR 12
#define BTRFS_FS_LOG2_ERR 13
+/*
+ * Indicate that a whole-filesystem exclusive operation is running
+ * (device replace, resize, device add/delete, balance)
+ */
+#define BTRFS_FS_EXCL_OP 14
struct btrfs_fs_info {
u8 fsid[BTRFS_FSID_SIZE];
@@ -1070,8 +1075,6 @@
/* device replace state */
struct btrfs_dev_replace dev_replace;
- atomic_t mutually_exclusive_operation_running;
-
struct percpu_counter bio_counter;
wait_queue_head_t replace_wait;
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index e653921..de7b2c8 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -784,8 +784,7 @@
}
btrfs_dev_replace_unlock(dev_replace, 1);
- WARN_ON(atomic_xchg(
- &fs_info->mutually_exclusive_operation_running, 1));
+ WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
return PTR_ERR_OR_ZERO(task);
}
@@ -814,7 +813,7 @@
(unsigned int)progress);
}
btrfs_dev_replace_continue_on_mount(fs_info);
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
return 0;
}
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index dabfc7a..a29dc3f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1504,7 +1504,7 @@
if (ret)
return ret;
- if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {
+ if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
mnt_drop_write_file(file);
return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
}
@@ -1619,7 +1619,7 @@
kfree(vol_args);
out:
mutex_unlock(&fs_info->volume_mutex);
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
mnt_drop_write_file(file);
return ret;
}
@@ -2661,7 +2661,7 @@
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1))
+ if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags))
return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
mutex_lock(&fs_info->volume_mutex);
@@ -2680,7 +2680,7 @@
kfree(vol_args);
out:
mutex_unlock(&fs_info->volume_mutex);
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
return ret;
}
@@ -2708,7 +2708,7 @@
if (vol_args->flags & ~BTRFS_VOL_ARG_V2_FLAGS_SUPPORTED)
return -EOPNOTSUPP;
- if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {
+ if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
goto out;
}
@@ -2721,7 +2721,7 @@
ret = btrfs_rm_device(fs_info, vol_args->name, 0);
}
mutex_unlock(&fs_info->volume_mutex);
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
if (!ret) {
if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID)
@@ -2752,7 +2752,7 @@
if (ret)
return ret;
- if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {
+ if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
goto out_drop_write;
}
@@ -2772,7 +2772,7 @@
btrfs_info(fs_info, "disk deleted %s", vol_args->name);
kfree(vol_args);
out:
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
out_drop_write:
mnt_drop_write_file(file);
@@ -4442,13 +4442,11 @@
ret = -EROFS;
goto out;
}
- if (atomic_xchg(
- &fs_info->mutually_exclusive_operation_running, 1)) {
+ if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
} else {
ret = btrfs_dev_replace_by_ioctl(fs_info, p);
- atomic_set(
- &fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
}
break;
case BTRFS_IOCTL_DEV_REPLACE_CMD_STATUS:
@@ -4643,7 +4641,7 @@
return ret;
again:
- if (!atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {
+ if (!test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
mutex_lock(&fs_info->volume_mutex);
mutex_lock(&fs_info->balance_mutex);
need_unlock = true;
@@ -4689,7 +4687,7 @@
}
locked:
- BUG_ON(!atomic_read(&fs_info->mutually_exclusive_operation_running));
+ BUG_ON(!test_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
if (arg) {
bargs = memdup_user(arg, sizeof(*bargs));
@@ -4745,11 +4743,10 @@
do_balance:
/*
- * Ownership of bctl and mutually_exclusive_operation_running
+ * Ownership of bctl and filesystem flag BTRFS_FS_EXCL_OP
* goes to to btrfs_balance. bctl is freed in __cancel_balance,
* or, if restriper was paused all the way until unmount, in
- * free_fs_info. mutually_exclusive_operation_running is
- * cleared in __cancel_balance.
+ * free_fs_info. The flag is cleared in __cancel_balance.
*/
need_unlock = false;
@@ -4769,7 +4766,7 @@
mutex_unlock(&fs_info->balance_mutex);
mutex_unlock(&fs_info->volume_mutex);
if (need_unlock)
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
out:
mnt_drop_write_file(file);
return ret;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index df50a63..2e425a9 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3761,7 +3761,7 @@
if (ret)
btrfs_handle_fs_error(fs_info, ret, NULL);
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
}
/* Non-zero return value signifies invalidity */
@@ -3941,7 +3941,7 @@
__cancel_balance(fs_info);
else {
kfree(bctl);
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
}
return ret;
}
@@ -4031,7 +4031,7 @@
btrfs_balance_sys(leaf, item, &disk_bargs);
btrfs_disk_balance_args_to_cpu(&bctl->sys, &disk_bargs);
- WARN_ON(atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1));
+ WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
mutex_lock(&fs_info->volume_mutex);
mutex_lock(&fs_info->balance_mutex);