btrfs: trim enhancement to allow btrfs really trim block groups

Function btrfs_trim_fs() doesn't handle errors in a consistent way, if error happens when trimming existing block groups, it will skip the remaining blocks and continue to trim unallocated space for each device.

And the return value will only reflect the final error from device trimming.

This patch will fix such behavior by:

1) Recording last error from block group or device trimming So return value will also reflect the last error during trimming. Make developer more aware of the problem.

2) Continuing trimming if we can
If we failed to trim one block group or device, we could still try next block group or device.

3) Report number of failures during block group and device trimming So it would be less noisy, but still gives user a brief summary of what's going wrong.

Such behavior can avoid confusion for case like failure to trim the first block group and then only unallocated space is trimmed.

Reported-by Chris Murphy <[email protected]>

Signed-off-by Qu Wenruo <[email protected]>

---
 fs/btrfs/extent-tree.c | 57 ++++++++++++++++++++++++++++++------------
 1 file changed, 41 insertions(+), 16 deletions(-)

fs/btrfs/extent-tree.c +26 -12

index de6f75f5547b..7768f206196a 100644
@@ -10832,6 +10832,16 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 	return ret;
 }
 
+/*
+ * Trim the whole fs, by:
+ * 1) Trimming free space in each block group
+ * 2) Trimming unallocated space in each device
+ *
+ * Will try to continue trimming even if we failed to trim one block group or
+ * device.
+ * The return value will be the last error during trim.
+ * Or 0 if nothing wrong happened.
+ */
 int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 {
 	struct btrfs_block_group_cache *cache = NULL;

@@ -10842,6 +10852,10 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	u64 end;
 	u64 trimmed = 0;
 	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+	u64 bg_failed = 0;
+	u64 dev_failed = 0;
+	int bg_ret = 0;
+	int dev_ret = 0;
 	int ret = 0;
 
 	/*

@@ -10852,7 +10866,7 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	else
 		cache = btrfs_lookup_block_group(fs_info, range->start);
 
-	while (cache) {
+	for (; cache; cache = next_block_group(fs_info, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);
 			break;

@@ -10866,45 +10880,56 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 			if (!block_group_cache_done(cache)) {
 				ret = cache_block_group(cache, 0);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 				ret = wait_block_group_cache_done(cache);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 			}
-			ret = btrfs_trim_block_group(cache,
-						     &group_trimmed,
-						     start,
-						     end,
-						     range->minlen);
+			ret = btrfs_trim_block_group(cache, &group_trimmed,
+						start, end, range->minlen);
 
 			trimmed += group_trimmed;
 			if (ret) {
-				btrfs_put_block_group(cache);
-				break;
+				bg_failed++;
+				bg_ret = ret;
+				continue;

fs/btrfs/extent-tree.c +3 -1

 	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) {
 		ret = btrfs_trim_free_extents(device, range->minlen,
 					      &group_trimmed);
-		if (ret)
+		if (ret) {
+			dev_failed++;
+			dev_ret = ret;
 			break;

fs/btrfs/extent-tree.c +3 -1

 	range->len = trimmed;
-	return ret;
+	if (bg_ret)
+		return bg_ret;
+	return dev_ret;
 }
 
 /*

Quoted 105 lines · Qu Wenruo

Function btrfs_trim_fs() doesn't handle errors in a consistent way, if error happens when trimming existing block groups, it will skip the remaining blocks and continue to trim unallocated space for each device.

And the return value will only reflect the final error from device trimming.

This patch will fix such behavior by:

1) Recording last error from block group or device trimming So return value will also reflect the last error during trimming. Make developer more aware of the problem.

2) Continuing trimming if we can
If we failed to trim one block group or device, we could still try next block group or device.

3) Report number of failures during block group and device trimming So it would be less noisy, but still gives user a brief summary of what's going wrong.

Such behavior can avoid confusion for case like failure to trim the first block group and then only unallocated space is trimmed.

Reported-by Chris Murphy <[email protected]>

Signed-off-by Qu Wenruo <[email protected]>

---
 fs/btrfs/extent-tree.c | 57 ++++++++++++++++++++++++++++++------------
 1 file changed, 41 insertions(+), 16 deletions(-)

fs/btrfs/extent-tree.c +26 -12

index de6f75f5547b..7768f206196a 100644
@@ -10832,6 +10832,16 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 	return ret;
 }
 
+/*
+ * Trim the whole fs, by:
+ * 1) Trimming free space in each block group
+ * 2) Trimming unallocated space in each device
+ *
+ * Will try to continue trimming even if we failed to trim one block group or
+ * device.
+ * The return value will be the last error during trim.
+ * Or 0 if nothing wrong happened.
+ */
 int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 {
 	struct btrfs_block_group_cache *cache = NULL;

@@ -10842,6 +10852,10 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	u64 end;
 	u64 trimmed = 0;
 	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+	u64 bg_failed = 0;
+	u64 dev_failed = 0;
+	int bg_ret = 0;
+	int dev_ret = 0;
 	int ret = 0;
 
 	/*

@@ -10852,7 +10866,7 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	else
 		cache = btrfs_lookup_block_group(fs_info, range->start);
 
-	while (cache) {
+	for (; cache; cache = next_block_group(fs_info, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);
 			break;

@@ -10866,45 +10880,56 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 			if (!block_group_cache_done(cache)) {
 				ret = cache_block_group(cache, 0);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 				ret = wait_block_group_cache_done(cache);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 			}
-			ret = btrfs_trim_block_group(cache,
-						     &group_trimmed,
-						     start,
-						     end,
-						     range->minlen);
+			ret = btrfs_trim_block_group(cache, &group_trimmed,
+						start, end, range->minlen);
 
 			trimmed += group_trimmed;
 			if (ret) {
-				btrfs_put_block_group(cache);
-				break;
+				bg_failed++;
+				bg_ret = ret;
+				continue;

fs/btrfs/extent-tree.c int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) · line 10909

Quoted 10 lines

fs/btrfs/extent-tree.c +4 -2

 			}
 		}
-
-		cache = next_block_group(fs_info, cache);
 	}
 
+	if (bg_failed)
+		btrfs_warn(fs_info,
+		"failed to trim %llu block group(s), last error was %d",
+			   bg_failed, bg_ret);

IMO this error handling strategy doesn't really bring any value. The only thing which the user really gathers from that error message is that N block groups failed. But there is no information whether it failed due to read failure hence cannot load the freespace cache or there was some error during the actual trimming.

I agree that if we fail for 1 bg we shouldn't terminate the whole process but just skip it. However, a more useful error handling strategy would be to have btrfs_warns for every failed block group for every failed function.

I.e one for wait_block_group_cache since the low-level code in cache_block_group already prints something if it encounters errors. And one for btrfs_trim_block_group

Quoted 10 lines

fs/btrfs/extent-tree.c +3 -1

 	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) {
 		ret = btrfs_trim_free_extents(device, range->minlen,
 					      &group_trimmed);
-		if (ret)
+		if (ret) {
+			dev_failed++;
+			dev_ret = ret;
 			break;

fs/btrfs/extent-tree.c int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) · line 10928

Quoted 10 lines

fs/btrfs/extent-tree.c +5 -0

+		}
 
 		trimmed += group_trimmed;
 	}
 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 
+	if (dev_failed)
+		btrfs_warn(fs_info,
+		"failed to trim %llu device(s), last error was %d",
+			   dev_failed, dev_ret);

Same thing here, I'd rather see one message per device error and also identify the device by name.

Quoted 9 lines

fs/btrfs/extent-tree.c +3 -1

 	range->len = trimmed;
-	return ret;
+	if (bg_ret)
+		return bg_ret;
+	return dev_ret;
 }
 
 /*

Quoted 125 lines · Nikolay Borisov

Quoted 105 lines · Qu Wenruo

Function btrfs_trim_fs() doesn't handle errors in a consistent way, if error happens when trimming existing block groups, it will skip the remaining blocks and continue to trim unallocated space for each device.

And the return value will only reflect the final error from device trimming.

This patch will fix such behavior by:

1) Recording last error from block group or device trimming So return value will also reflect the last error during trimming. Make developer more aware of the problem.

2) Continuing trimming if we can
If we failed to trim one block group or device, we could still try next block group or device.

3) Report number of failures during block group and device trimming So it would be less noisy, but still gives user a brief summary of what's going wrong.

Such behavior can avoid confusion for case like failure to trim the first block group and then only unallocated space is trimmed.

Reported-by Chris Murphy <[email protected]>

Signed-off-by Qu Wenruo <[email protected]>

---
 fs/btrfs/extent-tree.c | 57 ++++++++++++++++++++++++++++++------------
 1 file changed, 41 insertions(+), 16 deletions(-)

fs/btrfs/extent-tree.c +26 -12

index de6f75f5547b..7768f206196a 100644
@@ -10832,6 +10832,16 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 	return ret;
 }
 
+/*
+ * Trim the whole fs, by:
+ * 1) Trimming free space in each block group
+ * 2) Trimming unallocated space in each device
+ *
+ * Will try to continue trimming even if we failed to trim one block group or
+ * device.
+ * The return value will be the last error during trim.
+ * Or 0 if nothing wrong happened.
+ */
 int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 {
 	struct btrfs_block_group_cache *cache = NULL;

@@ -10842,6 +10852,10 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	u64 end;
 	u64 trimmed = 0;
 	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+	u64 bg_failed = 0;
+	u64 dev_failed = 0;
+	int bg_ret = 0;
+	int dev_ret = 0;
 	int ret = 0;
 
 	/*

@@ -10852,7 +10866,7 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	else
 		cache = btrfs_lookup_block_group(fs_info, range->start);
 
-	while (cache) {
+	for (; cache; cache = next_block_group(fs_info, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);
 			break;

@@ -10866,45 +10880,56 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 			if (!block_group_cache_done(cache)) {
 				ret = cache_block_group(cache, 0);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 				ret = wait_block_group_cache_done(cache);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 			}
-			ret = btrfs_trim_block_group(cache,
-						     &group_trimmed,
-						     start,
-						     end,
-						     range->minlen);
+			ret = btrfs_trim_block_group(cache, &group_trimmed,
+						start, end, range->minlen);
 
 			trimmed += group_trimmed;
 			if (ret) {
-				btrfs_put_block_group(cache);
-				break;
+				bg_failed++;
+				bg_ret = ret;
+				continue;

fs/btrfs/extent-tree.c int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) · line 10909

Quoted 10 lines

fs/btrfs/extent-tree.c +4 -2

 			}
 		}
-
-		cache = next_block_group(fs_info, cache);
 	}
 
+	if (bg_failed)
+		btrfs_warn(fs_info,
+		"failed to trim %llu block group(s), last error was %d",
+			   bg_failed, bg_ret);

IMO this error handling strategy doesn't really bring any value. The only thing which the user really gathers from that error message is that N block groups failed. But there is no information whether it failed due to read failure hence cannot load the freespace cache or there was some error during the actual trimming.

Quoted 4 lines

I agree that if we fail for 1 bg we shouldn't terminate the whole process but just skip it. However, a more useful error handling strategy would be to have btrfs_warns for every failed block group for every failed function.

Yep, previous version goes that way.

But even for btrfs_warn_rl() it could be too noisy.
And just as commented by David, user may not even care, thus such too noisy report makes not much sense.

E.g. if something really went wrong and make the fs RO, then there will be tons of error messages flooding dmesg (although most of them will be rate limited), and really makes no sense.

Thanks,
Qu

Quoted 37 lines

I.e one for wait_block_group_cache since the low-level code in cache_block_group already prints something if it encounters errors. And one for btrfs_trim_block_group

Quoted 10 lines

fs/btrfs/extent-tree.c +3 -1

 	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) {
 		ret = btrfs_trim_free_extents(device, range->minlen,
 					      &group_trimmed);
-		if (ret)
+		if (ret) {
+			dev_failed++;
+			dev_ret = ret;
 			break;

fs/btrfs/extent-tree.c int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) · line 10928

Quoted 10 lines

fs/btrfs/extent-tree.c +5 -0

+		}
 
 		trimmed += group_trimmed;
 	}
 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 
+	if (dev_failed)
+		btrfs_warn(fs_info,
+		"failed to trim %llu device(s), last error was %d",
+			   dev_failed, dev_ret);

Same thing here, I'd rather see one message per device error and also identify the device by name.

Quoted 9 lines

fs/btrfs/extent-tree.c +3 -1

 	range->len = trimmed;
-	return ret;
+	if (bg_ret)
+		return bg_ret;
+	return dev_ret;
 }
 
 /*

Quoted 139 lines · Qu Wenruo

Quoted 125 lines · Nikolay Borisov

Quoted 105 lines · Qu Wenruo

Function btrfs_trim_fs() doesn't handle errors in a consistent way, if error happens when trimming existing block groups, it will skip the remaining blocks and continue to trim unallocated space for each device.

And the return value will only reflect the final error from device trimming.

This patch will fix such behavior by:

1) Recording last error from block group or device trimming So return value will also reflect the last error during trimming. Make developer more aware of the problem.

2) Continuing trimming if we can
If we failed to trim one block group or device, we could still try next block group or device.

3) Report number of failures during block group and device trimming So it would be less noisy, but still gives user a brief summary of what's going wrong.

Such behavior can avoid confusion for case like failure to trim the first block group and then only unallocated space is trimmed.

Reported-by Chris Murphy <[email protected]>

Signed-off-by Qu Wenruo <[email protected]>

---
 fs/btrfs/extent-tree.c | 57 ++++++++++++++++++++++++++++++------------
 1 file changed, 41 insertions(+), 16 deletions(-)

fs/btrfs/extent-tree.c +26 -12

index de6f75f5547b..7768f206196a 100644
@@ -10832,6 +10832,16 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 	return ret;
 }
 
+/*
+ * Trim the whole fs, by:
+ * 1) Trimming free space in each block group
+ * 2) Trimming unallocated space in each device
+ *
+ * Will try to continue trimming even if we failed to trim one block group or
+ * device.
+ * The return value will be the last error during trim.
+ * Or 0 if nothing wrong happened.
+ */
 int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 {
 	struct btrfs_block_group_cache *cache = NULL;

@@ -10842,6 +10852,10 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	u64 end;
 	u64 trimmed = 0;
 	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+	u64 bg_failed = 0;
+	u64 dev_failed = 0;
+	int bg_ret = 0;
+	int dev_ret = 0;
 	int ret = 0;
 
 	/*

@@ -10852,7 +10866,7 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	else
 		cache = btrfs_lookup_block_group(fs_info, range->start);
 
-	while (cache) {
+	for (; cache; cache = next_block_group(fs_info, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);
 			break;

@@ -10866,45 +10880,56 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 			if (!block_group_cache_done(cache)) {
 				ret = cache_block_group(cache, 0);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 				ret = wait_block_group_cache_done(cache);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 			}
-			ret = btrfs_trim_block_group(cache,
-						     &group_trimmed,
-						     start,
-						     end,
-						     range->minlen);
+			ret = btrfs_trim_block_group(cache, &group_trimmed,
+						start, end, range->minlen);
 
 			trimmed += group_trimmed;
 			if (ret) {
-				btrfs_put_block_group(cache);
-				break;
+				bg_failed++;
+				bg_ret = ret;
+				continue;

fs/btrfs/extent-tree.c int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) · line 10909

Quoted 10 lines

fs/btrfs/extent-tree.c +4 -2

 			}
 		}
-
-		cache = next_block_group(fs_info, cache);
 	}
 
+	if (bg_failed)
+		btrfs_warn(fs_info,
+		"failed to trim %llu block group(s), last error was %d",
+			   bg_failed, bg_ret);

IMO this error handling strategy doesn't really bring any value. The only thing which the user really gathers from that error message is that N block groups failed. But there is no information whether it failed due to read failure hence cannot load the freespace cache or there was some error during the actual trimming.

Quoted 4 lines

I agree that if we fail for 1 bg we shouldn't terminate the whole process but just skip it. However, a more useful error handling strategy would be to have btrfs_warns for every failed block group for every failed function.

Yep, previous version goes that way.

But even for btrfs_warn_rl() it could be too noisy.
And just as commented by David, user may not even care, thus such too noisy report makes not much sense.

Quoted 3 lines

E.g. if something really went wrong and make the fs RO, then there will be tons of error messages flooding dmesg (although most of them will be rate limited), and really makes no sense.

Well in that case I don't see value in retaining the last error message so you can just leave the "%llu block groups failed to be trimmed" messages. The last error is not meaningful.

[BUG]
fstrim on some btrfs only trims the unallocated space, not trimming any space in existing block groups.

[CAUSE]
Before fstrim_range passed to btrfs_trim_fs(), it get truncated to range [0, super->total_bytes).
So later btrfs_trim_fs() will only be able to trim block groups in range [0, super->total_bytes).

While for btrfs, any bytenr aligned to sector size is valid, since btrfs use its logical address space, there is nothing limiting the location where we put block groups.

For btrfs with routine balance, it's quite easy to relocate all block groups and bytenr of block groups will start beyond super->total_bytes.

In that case, btrfs will not trim existing block groups.

[FIX]
Just remove the truncation in btrfs_ioctl_fitrim(), so btrfs_trim_fs() can get the unmodified range, which is normally set to [0, U64_MAX].

Reported-by Chris Murphy <[email protected]>

Fixes f4c697e6406d ("btrfs: return EINVAL if start > total_bytes in fitrim ioctl")

Cc <[email protected]> # v4.0+

Signed-off-by Qu Wenruo <[email protected]>

---
 fs/btrfs/extent-tree.c | 10 +---------
 fs/btrfs/ioctl.c       | 11 +++++++----
 2 files changed, 8 insertions(+), 13 deletions(-)

fs/btrfs/extent-tree.c +1 -9

index 7768f206196a..d1478d66c7a5 100644
@@ -10851,21 +10851,13 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 	u64 start;
 	u64 end;
 	u64 trimmed = 0;
-	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
 	u64 bg_failed = 0;
 	u64 dev_failed = 0;
 	int bg_ret = 0;
 	int dev_ret = 0;
 	int ret = 0;
 
-	/*
-	 * try to trim all FS space, our block group may start from non-zero.
-	 */
-	if (range->len == total_bytes)
-		cache = btrfs_lookup_first_block_group(fs_info, range->start);
-	else
-		cache = btrfs_lookup_block_group(fs_info, range->start);
-
+	cache = btrfs_lookup_first_block_group(fs_info, range->start);
 	for (; cache; cache = next_block_group(fs_info, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);

fs/btrfs/ioctl.c +7 -4

index 63600dc2ac4c..8165a4bfa579 100644
@@ -491,7 +491,6 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
 	struct fstrim_range range;
 	u64 minlen = ULLONG_MAX;
 	u64 num_devices = 0;
-	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
 	int ret;
 
 	if (!capable(CAP_SYS_ADMIN))

@@ -515,11 +514,15 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
 		return -EOPNOTSUPP;
 	if (copy_from_user(&range, arg, sizeof(range)))
 		return -EFAULT;
-	if (range.start > total_bytes ||
-	    range.len < fs_info->sb->s_blocksize)
+
+	/*
+	 * NOTE: Don't truncate the range using super->total_bytes.
+	 * Bytenr of btrfs block group is in btrfs logical address space,
+	 * which can be any sector size aligned bytenr in [0, U64_MAX].
+	 */
+	if (range.len < fs_info->sb->s_blocksize)
 		return -EINVAL;
 
-	range.len = min(range.len, total_bytes - range.start);
 	range.minlen = max(range.minlen, minlen);
 	ret = btrfs_trim_fs(fs_info, &range);
 	if (ret < 0)