[PATCH for 4.14.x] Revert "btrfs: Honour FITRIM range constraints during free space trim"

[David Sterba <dsterba@suse.com>]

This reverts commit b327ff8a9b5767ce39db650d468fb124b48974a5.

There is currently no corresponding patch in master due to additional
changes that would be significantly different from plain revert in the
respective stable branch.

The range argument was not handled correctly and could cause trim to
overlap allocated areas or reach beyond the end of the device. The
address space that fitrim normally operates on is in logical
coordinates, while the discards are done on the physical device extents.
This distinction cannot be made with the current ioctl interface and
caused the confusion.

The bug depends on the layout of block groups and does not always
happen. The whole-fs trim (run by default by the fstrim tool) is not
affected.

Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/extent-tree.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 54bb5d79723a..83791d13c204 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11058,9 +11058,9 @@ int btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info,
  * transaction.
  */
 static int btrfs_trim_free_extents(struct btrfs_device *device,
-				   struct fstrim_range *range, u64 *trimmed)
+				   u64 minlen, u64 *trimmed)
 {
-	u64 start = range->start, len = 0;
+	u64 start = 0, len = 0;
 	int ret;
 
 	*trimmed = 0;
@@ -11096,8 +11096,8 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 			refcount_inc(&trans->use_count);
 		spin_unlock(&fs_info->trans_lock);
 
-		ret = find_free_dev_extent_start(trans, device, range->minlen,
-						 start, &start, &len);
+		ret = find_free_dev_extent_start(trans, device, minlen, start,
+						 &start, &len);
 		if (trans)
 			btrfs_put_transaction(trans);
 
@@ -11109,16 +11109,6 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 			break;
 		}
 
-		/* If we are out of the passed range break */
-		if (start > range->start + range->len - 1) {
-			mutex_unlock(&fs_info->chunk_mutex);
-			ret = 0;
-			break;
-		}
-
-		start = max(range->start, start);
-		len = min(range->len, len);
-
 		ret = btrfs_issue_discard(device->bdev, start, len, &bytes);
 		up_read(&fs_info->commit_root_sem);
 		mutex_unlock(&fs_info->chunk_mutex);
@@ -11129,10 +11119,6 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 		start += len;
 		*trimmed += bytes;
 
-		/* We've trimmed enough */
-		if (*trimmed >= range->len)
-			break;
-
 		if (fatal_signal_pending(current)) {
 			ret = -ERESTARTSYS;
 			break;
@@ -11216,7 +11202,8 @@ 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->devices;
 	list_for_each_entry(device, devices, dev_list) {
-		ret = btrfs_trim_free_extents(device, range, &group_trimmed);
+		ret = btrfs_trim_free_extents(device, range->minlen,
+					      &group_trimmed);
 		if (ret) {
 			dev_failed++;
 			dev_ret = ret;
-- 
2.21.0