On 10.01.2018 07:16, Anand Jain wrote:
> Instead of pointer to btrfs_fs_devices as an arg in device_list_add()
> better to get pointer to btrfs_device as return value, then we have
> both, pointer to btrfs_device and btrfs_fs_devices. btrfs_device is
> needed to handle reappearing missing device.
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> ---
> fs/btrfs/volumes.c | 34 ++++++++++++++++++----------------
> 1 file changed, 18 insertions(+), 16 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 4e5b82976455..b5305bd48338 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -726,12 +726,11 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
> * Add new device to list of registered devices
> *
> * Returns:
> - * 0 - device already known or newly added
> - * < 0 - error
> + * device pointer which was just added or updated when successful
> + * error pointer when failed
> */
> -static noinline int device_list_add(const char *path,
> - struct btrfs_super_block *disk_super,
> - u64 devid, struct btrfs_fs_devices **fs_devices_ret)
> +static noinline struct btrfs_device *device_list_add(const char *path,
> + struct btrfs_super_block *disk_super, u64 devid)
> {
> struct btrfs_device *device;
> struct btrfs_fs_devices *fs_devices;
> @@ -742,7 +741,7 @@ static noinline int device_list_add(const char *path,
> if (!fs_devices) {
> fs_devices = alloc_fs_devices(disk_super->fsid);
> if (IS_ERR(fs_devices))
> - return PTR_ERR(fs_devices);
> + return ERR_PTR(PTR_ERR(fs_devices));
No need to do any conversion, alloc_fs_devices already returns ERR_PTR
value so plain return fs_devices suffices.
>
> list_add(&fs_devices->list, &fs_uuids);
>
> @@ -754,19 +753,19 @@ static noinline int device_list_add(const char *path,
>
> if (!device) {
> if (fs_devices->opened)
> - return -EBUSY;
> + return ERR_PTR(-EBUSY);
>
> device = btrfs_alloc_device(NULL, &devid,
> disk_super->dev_item.uuid);
> if (IS_ERR(device)) {
> /* we can safely leave the fs_devices entry around */
> - return PTR_ERR(device);
> + return ERR_PTR(PTR_ERR(device));
Ditto
> }
>
> name = rcu_string_strdup(path, GFP_NOFS);
> if (!name) {
> free_device(device);
> - return -ENOMEM;
> + return ERR_PTR(-ENOMEM);
> }
> rcu_assign_pointer(device->name, name);
>
> @@ -820,12 +819,12 @@ static noinline int device_list_add(const char *path,
> * with larger generation number or the last-in if
> * generation are equal.
> */
> - return -EEXIST;
> + return ERR_PTR(-EEXIST);
> }
>
> name = rcu_string_strdup(path, GFP_NOFS);
> if (!name)
> - return -ENOMEM;
> + return ERR_PTR(-ENOMEM);
> rcu_string_free(device->name);
> rcu_assign_pointer(device->name, name);
> if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
> @@ -845,9 +844,7 @@ static noinline int device_list_add(const char *path,
>
> fs_devices->total_devices = btrfs_super_num_devices(disk_super);
>
> - *fs_devices_ret = fs_devices;
> -
> - return 0;
> + return device;
> }
>
> static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
> @@ -1182,9 +1179,10 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
> struct btrfs_fs_devices **fs_devices_ret)
> {
> struct btrfs_super_block *disk_super;
> + struct btrfs_device *device;
> struct block_device *bdev;
> struct page *page;
> - int ret;
> + int ret = 0;
> u64 devid;
> u64 bytenr;
>
> @@ -1209,8 +1207,12 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
> devid = btrfs_stack_device_id(&disk_super->dev_item);
>
> mutex_lock(&uuid_mutex);
> - ret = device_list_add(path, disk_super, devid, fs_devices_ret);
> + device = device_list_add(path, disk_super, devid);
> mutex_unlock(&uuid_mutex);
> + if (IS_ERR(device))
> + ret = PTR_ERR(device);
> +
> + *fs_devices_ret = device->fs_devices;
>
> btrfs_release_disk_super(page);
>
>
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