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authorJosef Bacik <josef@toxicpanda.com>2021-10-05 16:12:43 -0400
committerDavid Sterba <dsterba@suse.com>2021-10-26 19:08:07 +0200
commitfaa775c41d655a4786e9d53cb075a77bb5a75f66 (patch)
tree72087feb56f555f84f6632d57650b84049482809 /fs/btrfs/volumes.c
parent562d7b1512f7369a19bca2883e2e8672d78f0481 (diff)
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btrfs: add a btrfs_get_dev_args_from_path helper
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>
Diffstat (limited to 'fs/btrfs/volumes.c')
-rw-r--r--fs/btrfs/volumes.c96
1 files changed, 64 insertions, 32 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index eddd2e50cb65..340583942d22 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -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 (ret)
- return ERR_PTR(ret);
+ 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;
+ }
- args.devid = btrfs_stack_device_id(&disk_super->dev_item);
- args.uuid = disk_super->dev_item.uuid;
+ ret = btrfs_get_bdev_and_sb(path, FMODE_READ, fs_info->bdev_holder, 0,
+ &bdev, &disk_super);
+ if (ret)
+ 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;
}
/*