From 171938e528079deced3226a17dcab12121312a64 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Tue, 28 Mar 2017 14:44:21 +0200 Subject: 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 Signed-off-by: David Sterba --- fs/btrfs/ioctl.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) (limited to 'fs/btrfs/ioctl.c') diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index dabfc7ac48a6..a29dc3fd7152 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1504,7 +1504,7 @@ static noinline int btrfs_ioctl_resize(struct file *file, 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 @@ out_free: 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 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg) 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 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg) 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 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg) 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 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg) 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 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) 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 @@ 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: - 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 @@ static long btrfs_ioctl_dev_replace(struct btrfs_fs_info *fs_info, 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 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg) 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 @@ again: } 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 @@ locked: 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 @@ out_unlock: 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; -- cgit v1.2.3-55-g7522