Signed-off-by: Nikolay Borisov <nbori...@suse.com>
---
V2:
* Document post_commit_list is protected by chunk_mutex in the "Device Locking"
section.
fs/btrfs/volumes.c | 4 +++-
fs/btrfs/volumes.h | 11 ++++++++---
2 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b85ff32f851c..83603be86891 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -237,7 +237,9 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
* chunk_mutex
* -----------
* protects chunks, adding or removing during allocation, trim or when a new
- * device is added/removed
+ * device is added/removed. Additionally it also protects post_commit_list of
+ * individual devices, since they can be added to the transaction's
+ * post_commit_list only with chunk_mutex held.
*
* cleaner_mutex
* -------------
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 3b97e8092ba7..514799362244 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -52,8 +52,8 @@ struct btrfs_io_geometry {
#define BTRFS_DEV_STATE_FLUSH_SENT (4)
struct btrfs_device {
- struct list_head dev_list;
- struct list_head dev_alloc_list;
+ struct list_head dev_list; /* device_list_mutex */
+ struct list_head dev_alloc_list; /* chunk mutex */
struct list_head post_commit_list; /* chunk mutex */
struct btrfs_fs_devices *fs_devices;
struct btrfs_fs_info *fs_info;
@@ -238,9 +238,14 @@ struct btrfs_fs_devices {
* this mutex lock.
*/
struct mutex device_list_mutex;
+
+ /* List of all devices, protected by device_list_mutex */
struct list_head devices;
- /* devices not currently being allocated */
+ /*
+ * Devices which can satisfy space allocation. Protected by
+ * chunk_mutex
+ */
struct list_head alloc_list;
struct btrfs_fs_devices *seed;
--
2.17.1
