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btrfs: move device->name RCU allocation and assign to btrfs_alloc_device()

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There is a repeating code section in the parent function after calling
btrfs_alloc_device(), as below:

      name = rcu_string_strdup(path, GFP_...);
      if (!name) {
              btrfs_free_device(device);
              return ERR_PTR(-ENOMEM);
      }
      rcu_assign_pointer(device->name, name);

Except in add_missing_dev() for obvious reasons.

This patch consolidates that repeating code into the btrfs_alloc_device()
itself so that the parent function doesn't have to duplicate code.
This consolidation also helps to review issues regarding RCU lock
violation with device->name.

Parent function device_list_add() and add_missing_dev() use GFP_NOFS for
the allocation, whereas the rest of the parent functions use GFP_KERNEL,
so bring the NOFS allocation context using memalloc_nofs_save() in the
function device_list_add() and add_missing_dev() is already doing it.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Anand Jain 2022-11-07 23:07:17 +08:00 • committed by David Sterba
parent 3e09b5b229
commit bb21e30260
3 changed files with 34 additions and 48 deletions
Download patch file Download diff file Expand all files Collapse all files

10
fs/btrfs/dev-replace.c
View file

@ -249,7 +249,6 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
struct btrfs_device *device;
struct block_device *bdev;
struct rcu_string *name;
u64 devid = BTRFS_DEV_REPLACE_DEVID;
int ret = 0;
@ -293,19 +292,12 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
}
device = btrfs_alloc_device(NULL, &devid, NULL);
device = btrfs_alloc_device(NULL, &devid, NULL, device_path);
if (IS_ERR(device)) {
ret = PTR_ERR(device);
goto error;
}
name = rcu_string_strdup(device_path, GFP_KERNEL);
if (!name) {
btrfs_free_device(device);
ret = -ENOMEM;
goto error;
}
rcu_assign_pointer(device->name, name);
ret = lookup_bdev(device_path, &device->devt);
if (ret)
goto error;