[PATCH 1/3] btrfs: use ->devices list instead of ->alloc_list in btrfs_trim_fs

[jeffm]

From: Jeff Mahoney <je...@suse.com>

btrfs_trim_fs iterates over the fs_devices->alloc_list while holding
the device_list_mutex.  The problem is that ->alloc_list is protected
by the chunk mutex.  We don't want to hold the chunk mutex over
the trim of the entire file system.  Fortunately, the ->dev_list
list is protected by the dev_list mutex and while it will give us
all devices, including read-only devices, we already just skip the
read-only devices.  Then we can continue to take and release the chunk
mutex while scanning each device.

Fixes: 499f377f49f (btrfs: iterate over unused chunk space in FITRIM)
Signed-off-by: Jeff Mahoney <je...@suse.com>
---
 fs/btrfs/extent-tree.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3d9fe58c0080..a0e82589c3e8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11008,8 +11008,8 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct 
fstrim_range *range)
        }
 
        mutex_lock(&fs_info->fs_devices->device_list_mutex);
-       devices = &fs_info->fs_devices->alloc_list;
-       list_for_each_entry(device, devices, dev_alloc_list) {
+       devices = &fs_info->fs_devices->devices;
+       list_for_each_entry(device, devices, dev_list) {
                ret = btrfs_trim_free_extents(device, range->minlen,
                                              &group_trimmed);
                if (ret)
-- 
2.12.3