Commit d4e329de authored Sep 06, 2018 by Jeff Mahoney Committed by David Sterba Oct 15, 2018

btrfs: iterate all devices during trim, instead of fs_devices::alloc_list



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: 499f377f ("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>

parent 6ba9fc8e

fs/btrfs/extent-tree.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -10903,8 +10903,8 @@ int btrfs_trim_fs(struct btrfs_fs_info fs_info, struct fstrim_range range)
		"failed to trim %llu block group(s), last error %d",
		bg_failed, bg_ret);
		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) {

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