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btrfs: lift uuid_mutex to callers of btrfs_open_devices

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[ Upstream commit f5194e34cabaddd348a90f950e0a8188dd26cdc0 ]

Prepartory work to fix race between mount and device scan.

The callers will have to manage the critical section, eg. mount wants to
scan and then call btrfs_open_devices without the ioctl scan walking in
and modifying the fs devices in the meantime.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Sterba 2018-06-19 17:09:47 +02:00 committed by Greg Kroah-Hartman
parent f88b40c147
commit 122fe306d0
2 changed files with 4 additions and 2 deletions
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2
fs/btrfs/super.c
View File

@ -1565,7 +1565,9 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
goto error_fs_info;
}
mutex_lock(&uuid_mutex);
error = btrfs_open_devices(fs_devices, mode, fs_type);
mutex_unlock(&uuid_mutex);
if (error)
goto error_fs_info;

4
fs/btrfs/volumes.c
View File

@ -1146,7 +1146,8 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
{
int ret;
mutex_lock(&uuid_mutex);
lockdep_assert_held(&uuid_mutex);
mutex_lock(&fs_devices->device_list_mutex);
if (fs_devices->opened) {
fs_devices->opened++;
@ -1156,7 +1157,6 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
ret = open_fs_devices(fs_devices, flags, holder);
}
mutex_unlock(&fs_devices->device_list_mutex);
mutex_unlock(&uuid_mutex);
return ret;
}