[PATCH 1/2] btrfs: enumerate the type of exclusive operation in progress

Goldwyn Rodrigues
2020-08-25T15:02:47Z

Instead of using a flag bit for exclusive operation, use an atomic_t
variable to store if the exclusive operation is being performed.
Introduce an API to start and finish an exclusive operation.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
---
fs/btrfs/ctree.h | 24 +++++++++++++++++++-----
fs/btrfs/dev-replace.c | 4 ++--
fs/btrfs/inode.c | 4 ++--
fs/btrfs/ioctl.c | 36 +++++++++++++++++++++++-------------
fs/btrfs/volumes.c | 8 ++++----
5 files changed, 50 insertions(+), 26 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a3b110ffbc93..e7ac63446346 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -540,11 +540,6 @@ enum {
BTRFS_FS_QUOTA_OVERRIDE,
/* Used to record internally whether fs has been frozen */
BTRFS_FS_FROZEN,
- /*
- * Indicate that a whole-filesystem exclusive operation is running
- * (device replace, resize, device add/delete, balance)
- */
- BTRFS_FS_EXCL_OP,
/*
* Indicate that balance has been set up from the ioctl and is in the
* main phase. The fs_info::balance_ctl is initialized.
@@ -565,6 +560,20 @@ enum {
BTRFS_FS_DISCARD_RUNNING,
};

+/*
+ * Exclusive operation values
+ * (device replace, resize, device add/remove, balance)
+ */
+enum btrfs_exclusive_operation_t {
+ BTRFS_EXCLOP_NONE = 0,
+ BTRFS_EXCLOP_BALANCE,
+ BTRFS_EXCLOP_DEV_ADD,
+ BTRFS_EXCLOP_DEV_REPLACE,
+ BTRFS_EXCLOP_DEV_REMOVE,
+ BTRFS_EXCLOP_SWAP_ACTIVATE,
+ BTRFS_EXCLOP_RESIZE,
+};
+
struct btrfs_fs_info {
u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
unsigned long flags;
@@ -936,6 +945,9 @@ struct btrfs_fs_info {
*/
int send_in_progress;

+ /* Type of exclusive operation running */
+ atomic_t exclusive_operation;
+
#ifdef CONFIG_BTRFS_FS_REF_VERIFY
spinlock_t ref_verify_lock;
struct rb_root block_tree;
@@ -3034,6 +3046,8 @@ void btrfs_get_block_group_info(struct list_head *groups_list,
struct btrfs_ioctl_space_info *space);
void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
struct btrfs_ioctl_balance_args *bargs);
+bool btrfs_exclop_start(struct btrfs_fs_info *fs_info, int type);
+void btrfs_exclop_finish(struct btrfs_fs_info *fs_info);

/* file.c */
int __init btrfs_auto_defrag_init(void);
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 769ac3098880..3671a2039dad 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -983,7 +983,7 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
* should never allow both to start and pause. We don't want to allow
* dev-replace to start anyway.
*/
- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
down_write(&dev_replace->rwsem);
dev_replace->replace_state =
BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
@@ -1020,7 +1020,7 @@ static int btrfs_dev_replace_kthread(void *data)
ret = btrfs_dev_replace_finishing(fs_info, ret);
WARN_ON(ret && ret != -ECANCELED);

- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
return 0;
}

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 144b9bd79cfb..87d1b7888d1c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9978,7 +9978,7 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
* concurrent device add which isn't actually necessary, but it's not
* really worth the trouble to allow it.
*/
- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_SWAP_ACTIVATE)) {
btrfs_warn(fs_info,
"cannot activate swapfile while exclusive operation is running");
return -EBUSY;
@@ -10124,7 +10124,7 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
if (ret)
btrfs_swap_deactivate(file);

- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);

if (ret)
return ret;
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e45520d3cf51..256e58d42a7b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -378,6 +378,17 @@ static int check_xflags(unsigned int flags)
return 0;
}

+bool btrfs_exclop_start(struct btrfs_fs_info *fs_info, int type)
+{
+ return !atomic_cmpxchg(&fs_info->exclusive_operation, BTRFS_EXCLOP_NONE,
+ type);
+}
+
+void btrfs_exclop_finish(struct btrfs_fs_info *fs_info)
+{
+ atomic_set(&fs_info->exclusive_operation, BTRFS_EXCLOP_NONE);
+}
+
/*
* Set the xflags from the internal inode flags. The remaining items of fsxattr
* are zeroed.
@@ -1638,7 +1649,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
if (ret)
return ret;

- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_RESIZE)) {
mnt_drop_write_file(file);
return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
}
@@ -1752,7 +1763,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
out_free:
kfree(vol_args);
out:
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
mnt_drop_write_file(file);
return ret;
}
@@ -3112,7 +3123,7 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;

- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags))
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD))
return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;

vol_args = memdup_user(arg, sizeof(*vol_args));
@@ -3129,7 +3140,7 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)

kfree(vol_args);
out:
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
return ret;
}

@@ -3158,7 +3169,7 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
goto out;
}

- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REMOVE)) {
ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
goto out;
}
@@ -3169,7 +3180,7 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
ret = btrfs_rm_device(fs_info, vol_args->name, 0);
}
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);

if (!ret) {
if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID)
@@ -3200,7 +3211,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
if (ret)
return ret;

- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REMOVE)) {
ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
goto out_drop_write;
}
@@ -3218,7 +3229,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
btrfs_info(fs_info, "disk deleted %s", vol_args->name);
kfree(vol_args);
out:
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
out_drop_write:
mnt_drop_write_file(file);

@@ -3722,11 +3733,11 @@ static long btrfs_ioctl_dev_replace(struct btrfs_fs_info *fs_info,
ret = -EROFS;
goto out;
}
- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
} else {
ret = btrfs_dev_replace_by_ioctl(fs_info, p);
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
}
break;
case BTRFS_IOCTL_DEV_REPLACE_CMD_STATUS:
@@ -3937,7 +3948,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
return ret;

again:
- if (!test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ if (btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) {
mutex_lock(&fs_info->balance_mutex);
need_unlock = true;
goto locked;
@@ -3983,7 +3994,6 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
}

locked:
- BUG_ON(!test_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));

if (arg) {
bargs = memdup_user(arg, sizeof(*bargs));
@@ -4060,7 +4070,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
out_unlock:
mutex_unlock(&fs_info->balance_mutex);
if (need_unlock)
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
out:
mnt_drop_write_file(file);
return ret;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1d5026fdfc75..a65199f3dc2b 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4183,7 +4183,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
if ((ret && ret != -ECANCELED && ret != -ENOSPC) ||
balance_need_close(fs_info)) {
reset_balance_state(fs_info);
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
}

wake_up(&fs_info->balance_wait_q);
@@ -4194,7 +4194,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
reset_balance_state(fs_info);
else
kfree(bctl);
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);

return ret;
}
@@ -4296,7 +4296,7 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info)
* is in a paused state and must have fs_info::balance_ctl properly
* set up.
*/
- if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags))
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE))
btrfs_warn(fs_info,
"balance: cannot set exclusive op status, resume manually");

@@ -4378,7 +4378,7 @@ int btrfs_cancel_balance(struct btrfs_fs_info *fs_info)

if (fs_info->balance_ctl) {
reset_balance_state(fs_info);
- clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+ btrfs_exclop_finish(fs_info);
btrfs_info(fs_info, "balance: canceled");
}
}
--
2.26.2