btrfs: Honour FITRIM range constraints during free space trim

Up until now trimming the freespace was done irrespective of what the
arguments of the FITRIM ioctl were. For example fstrim's -o/-l arguments
will be entirely ignored. Fix it by correctly handling those paramter.
This requires breaking if the found freespace extent is after the end of
the passed range as well as completing trim after trimming
fstrim_range::len bytes.

Fixes: 499f377f49f0 ("btrfs: iterate over unused chunk space in FITRIM")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index aa52b0995fba7b41125abe7f1ec72e0d7311c481..c5f9e8359c6f7b58412c001daa4d8e507242c0e0 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11309,9 +11309,9 @@ int btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info,
  * held back allocations.
  */
 static int btrfs_trim_free_extents(struct btrfs_device *device,
-                                  u64 minlen, u64 *trimmed)
+                                  struct fstrim_range *range, u64 *trimmed)
 {
-       u64 start = 0, len = 0;
+       u64 start = range->start, len = 0;
        int ret;
 
        *trimmed = 0;
@@ -11354,8 +11354,8 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
                if (!trans)
                        up_read(&fs_info->commit_root_sem);
 
-               ret = find_free_dev_extent_start(trans, device, minlen, start,
-                                                &start, &len);
+               ret = find_free_dev_extent_start(trans, device, range->minlen,
+                                                start, &start, &len);
                if (trans) {
                        up_read(&fs_info->commit_root_sem);
                        btrfs_put_transaction(trans);
@@ -11368,6 +11368,16 @@ 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);
                mutex_unlock(&fs_info->chunk_mutex);
 
@@ -11377,6 +11387,10 @@ 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;
@@ -11460,8 +11474,7 @@ 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->minlen,
-                                             &group_trimmed);
+               ret = btrfs_trim_free_extents(device, range, &group_trimmed);
                if (ret) {
                        dev_failed++;
                        dev_ret = ret;