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btrfs: add a btrfs_get_dev_args_from_path helper

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We are going to want to populate our device lookup args outside of any
locks and then do the actual device lookup later, so add a helper to do
this work and make btrfs_find_device_by_devspec() use this helper for
now.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2021-10-05 16:12:43 -04:00 committed by David Sterba
parent 562d7b1512
commit faa775c41d
2 changed files with 68 additions and 32 deletions
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96
fs/btrfs/volumes.c
View File

@ -2325,45 +2325,81 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
btrfs_free_device(tgtdev);
}
static struct btrfs_device *btrfs_find_device_by_path(
struct btrfs_fs_info *fs_info, const char *device_path)
/**
* Populate args from device at path
*
* @fs_info: the filesystem
* @args: the args to populate
* @path: the path to the device
*
* This will read the super block of the device at @path and populate @args with
* the devid, fsid, and uuid. This is meant to be used for ioctls that need to
* lookup a device to operate on, but need to do it before we take any locks.
* This properly handles the special case of "missing" that a user may pass in,
* and does some basic sanity checks. The caller must make sure that @path is
* properly NUL terminated before calling in, and must call
* btrfs_put_dev_args_from_path() in order to free up the temporary fsid and
* uuid buffers.
*
* Return: 0 for success, -errno for failure
*/
int btrfs_get_dev_args_from_path(struct btrfs_fs_info *fs_info,
struct btrfs_dev_lookup_args *args,
const char *path)
{
BTRFS_DEV_LOOKUP_ARGS(args);
int ret = 0;
struct btrfs_super_block *disk_super;
struct block_device *bdev;
struct btrfs_device *device;
int ret;
ret = btrfs_get_bdev_and_sb(device_path, FMODE_READ,
fs_info->bdev_holder, 0, &bdev, &disk_super);
if (!path || !path[0])
return -EINVAL;
if (!strcmp(path, "missing")) {
args->missing = true;
return 0;
}
args->uuid = kzalloc(BTRFS_UUID_SIZE, GFP_KERNEL);
args->fsid = kzalloc(BTRFS_FSID_SIZE, GFP_KERNEL);
if (!args->uuid || !args->fsid) {
btrfs_put_dev_args_from_path(args);
return -ENOMEM;
}
ret = btrfs_get_bdev_and_sb(path, FMODE_READ, fs_info->bdev_holder, 0,
&bdev, &disk_super);
if (ret)
return ERR_PTR(ret);
args.devid = btrfs_stack_device_id(&disk_super->dev_item);
args.uuid = disk_super->dev_item.uuid;
return ret;
args->devid = btrfs_stack_device_id(&disk_super->dev_item);
memcpy(args->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE);
if (btrfs_fs_incompat(fs_info, METADATA_UUID))
args.fsid = disk_super->metadata_uuid;
memcpy(args->fsid, disk_super->metadata_uuid, BTRFS_FSID_SIZE);
else
args.fsid = disk_super->fsid;
device = btrfs_find_device(fs_info->fs_devices, &args);
memcpy(args->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
btrfs_release_disk_super(disk_super);
if (!device)
device = ERR_PTR(-ENOENT);
blkdev_put(bdev, FMODE_READ);
return device;
return 0;
}
/*
* Lookup a device given by device id, or the path if the id is 0.
* Only use this jointly with btrfs_get_dev_args_from_path() because we will
* allocate our ->uuid and ->fsid pointers, everybody else uses local variables
* that don't need to be freed.
*/
void btrfs_put_dev_args_from_path(struct btrfs_dev_lookup_args *args)
{
kfree(args->uuid);
kfree(args->fsid);
args->uuid = NULL;
args->fsid = NULL;
}
struct btrfs_device *btrfs_find_device_by_devspec(
struct btrfs_fs_info *fs_info, u64 devid,
const char *device_path)
{
BTRFS_DEV_LOOKUP_ARGS(args);
struct btrfs_device *device;
int ret;
if (devid) {
args.devid = devid;
@ -2373,18 +2409,14 @@ struct btrfs_device *btrfs_find_device_by_devspec(
return device;
}
if (!device_path || !device_path[0])
return ERR_PTR(-EINVAL);
if (strcmp(device_path, "missing") == 0) {
args.missing = true;
device = btrfs_find_device(fs_info->fs_devices, &args);
if (!device)
return ERR_PTR(-ENOENT);
return device;
}
return btrfs_find_device_by_path(fs_info, device_path);
ret = btrfs_get_dev_args_from_path(fs_info, &args, device_path);
if (ret)
return ERR_PTR(ret);
device = btrfs_find_device(fs_info->fs_devices, &args);
btrfs_put_dev_args_from_path(&args);
if (!device)
return ERR_PTR(-ENOENT);
return device;
}
/*

4
fs/btrfs/volumes.h
View File

@ -520,9 +520,13 @@ void btrfs_assign_next_active_device(struct btrfs_device *device,
struct btrfs_device *btrfs_find_device_by_devspec(struct btrfs_fs_info *fs_info,
u64 devid,
const char *devpath);
int btrfs_get_dev_args_from_path(struct btrfs_fs_info *fs_info,
struct btrfs_dev_lookup_args *args,
const char *path);
struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
const u64 *devid,
const u8 *uuid);
void btrfs_put_dev_args_from_path(struct btrfs_dev_lookup_args *args);
void btrfs_free_device(struct btrfs_device *device);
int btrfs_rm_device(struct btrfs_fs_info *fs_info,
const char *device_path, u64 devid,