4.9-stable review patch. If anyone has any objections, please let me know.
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From: Jeff Mahoney jeffm@suse.com
commit d4e329de5e5e21594df2e0dd59da9acee71f133b upstream.
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") CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Jeff Mahoney jeffm@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/extent-tree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -11193,8 +11193,8 @@ int btrfs_trim_fs(struct btrfs_root *roo }
mutex_lock(&root->fs_info->fs_devices->device_list_mutex); - devices = &root->fs_info->fs_devices->alloc_list; - list_for_each_entry(device, devices, dev_alloc_list) { + devices = &root->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)