diff mbox series

[v3.1,1/2] btrfs: Enhance btrfs_trim_fs function to handle error better

Message ID 20180907061624.20604-2-wqu@suse.com (mailing list archive)
State New, archived
Headers show
Series btrfs: trim enhancement to allow btrfs really trim block groups | expand

Commit Message

Qu Wenruo Sept. 7, 2018, 6:16 a.m. UTC
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 <lists@colorremedies.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/extent-tree.c | 55 ++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 16 deletions(-)

Comments

David Sterba Sept. 14, 2018, 3:57 p.m. UTC | #1
On Fri, Sep 07, 2018 at 02:16:23PM +0800, Qu Wenruo wrote:
> 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 <lists@colorremedies.com>
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Reviewed-by: David Sterba <dsterba@suse.com>

> -			ret = btrfs_trim_block_group(cache,
> -						     &group_trimmed,
> -						     start,
> -						     end,
> -						     range->minlen);
> +			ret = btrfs_trim_block_group(cache, &group_trimmed,
> +						start, end, range->minlen);

No unrealted changes please, this just reformats the argument list.
David Sterba Sept. 14, 2018, 4:05 p.m. UTC | #2
On Fri, Sep 07, 2018 at 02:16:23PM +0800, Qu Wenruo wrote:
> +	if (bg_failed)
> +		btrfs_warn(fs_info, "failed to trim %llu block group(s)",
> +			   bg_failed);

> +	if (dev_failed)
> +		btrfs_warn(fs_info, "failed to trim %llu device(s)",
> +			   dev_failed);

Minor update, I've added bg_ret and dev_ret to the messages as this will
end up in the logs and could be useful for later analysis.
diff mbox series

Patch

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index de6f75f5547b..2cc449190578 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -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 +10880,54 @@  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;
 			}
 		}
-
-		cache = next_block_group(fs_info, cache);
 	}
 
+	if (bg_failed)
+		btrfs_warn(fs_info, "failed to trim %llu block group(s)",
+			   bg_failed);
 	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;
+		}
 
 		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)",
+			   dev_failed);
 	range->len = trimmed;
-	return ret;
+	if (bg_ret)
+		return bg_ret;
+	return dev_ret;
 }
 
 /*