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* [PATCH] btrfs: relocation: Enhance kernel error output for relocation
@ 2017-02-13  7:26 Qu Wenruo
  2017-02-14  0:49 ` Liu Bo
  0 siblings, 1 reply; 2+ messages in thread
From: Qu Wenruo @ 2017-02-13  7:26 UTC (permalink / raw)
  To: linux-btrfs

When balance(relocation) fails, btrfs-progs will report like:

ERROR: error during balancing '/mnt/scratch': Input/output error
There may be more info in syslog - try dmesg | tail

However in some case, for example debugging btrfs/125 with small file
size, kernel only have some recoverable csum error message and nothing
useful at all.

This patch will add error messages in relocation to help both end user to
wipe out some obvious problems, like ENOSPC.
And for developers, they can locate the problem to specific function just
by kernel message.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 fs/btrfs/relocation.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 379711048fb0..c9474377a59c 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4011,6 +4011,8 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 					rc->block_rsv, rc->block_rsv->size,
 					BTRFS_RESERVE_FLUSH_ALL);
 		if (ret) {
+			btrfs_err(fs_info, "failed to reserve space: %d(%s)",
+				  ret, btrfs_decode_error(ret));
 			err = ret;
 			break;
 		}
@@ -4019,6 +4021,9 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 		if (IS_ERR(trans)) {
 			err = PTR_ERR(trans);
 			trans = NULL;
+			btrfs_err(fs_info,
+				  "failed to start transaction: %d(%s)",
+				  err, btrfs_decode_error(err));
 			break;
 		}
 restart:
@@ -4028,8 +4033,11 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 		}
 
 		ret = find_next_extent(rc, path, &key);
-		if (ret < 0)
+		if (ret < 0) {
+			btrfs_err(fs_info, "failed to find next extent: %d(%s)",
+				  ret, btrfs_decode_error(ret));
 			err = ret;
+		}
 		if (ret != 0)
 			break;
 
@@ -4081,9 +4089,17 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 
 		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 			ret = add_tree_block(rc, &key, path, &blocks);
+			if (ret < 0)
+				btrfs_err(fs_info,
+					  "failed to record tree block: %d(%s)",
+					  ret, btrfs_decode_error(ret));
 		} else if (rc->stage == UPDATE_DATA_PTRS &&
 			   (flags & BTRFS_EXTENT_FLAG_DATA)) {
 			ret = add_data_references(rc, &key, path, &blocks);
+			if (ret < 0)
+				btrfs_err(fs_info,
+					  "failed to record data extent: %d(%s)",
+					  ret, btrfs_decode_error(ret));
 		} else {
 			btrfs_release_path(path);
 			ret = 0;
@@ -4103,6 +4119,9 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 				rc->backref_cache.last_trans = trans->transid - 1;
 
 				if (ret != -EAGAIN) {
+					btrfs_err(fs_info,
+					"faild to relocate tree blocks: %d(%s)",
+						  ret, btrfs_decode_error(ret));
 					err = ret;
 					break;
 				}
@@ -4121,6 +4140,9 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 			ret = relocate_data_extent(rc->data_inode,
 						   &key, &rc->cluster);
 			if (ret < 0) {
+				btrfs_err(fs_info,
+				"failed to relocate data extent: %d(%s)",
+					  ret, btrfs_decode_error(ret));
 				err = ret;
 				break;
 			}
@@ -4147,8 +4169,12 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 	if (!err) {
 		ret = relocate_file_extent_cluster(rc->data_inode,
 						   &rc->cluster);
-		if (ret < 0)
+		if (ret < 0) {
+			btrfs_err(fs_info,
+			"failed to relocate file extent cluster: %d(%s)",
+				  ret, btrfs_decode_error(ret));
 			err = ret;
+		}
 	}
 
 	rc->create_reloc_tree = 0;
@@ -4158,6 +4184,10 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 	btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
 
 	err = prepare_to_merge(rc, err);
+	if (err < 0)
+		btrfs_err(fs_info,
+			  "failed to preapre merge relocate trees: %d(%s)",
+			  ret, btrfs_decode_error(ret));
 
 	merge_reloc_roots(rc);
 
@@ -4336,6 +4366,9 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
 
 	ret = btrfs_inc_block_group_ro(extent_root, rc->block_group);
 	if (ret) {
+		btrfs_err(fs_info,
+			"failed to set block group read-only: %d(%s)",
+			  err, btrfs_decode_error(err));
 		err = ret;
 		goto out;
 	}
@@ -4351,10 +4384,19 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
 					path);
 	btrfs_free_path(path);
 
-	if (!IS_ERR(inode))
+	if (!IS_ERR(inode)) {
 		ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
-	else
+		if (ret < 0)
+			btrfs_err(fs_info,
+				"failed to delete block group cache: %d(%s)",
+				  err, btrfs_decode_error(err));
+	} else {
 		ret = PTR_ERR(inode);
+		if (ret < 0 && ret != -ENOENT)
+			btrfs_err(fs_info,
+				"failed to lookup free space inode: %d(%s)",
+				  err, btrfs_decode_error(err));
+	}
 
 	if (ret && ret != -ENOENT) {
 		err = ret;
@@ -4364,6 +4406,8 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
 	rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
 	if (IS_ERR(rc->data_inode)) {
 		err = PTR_ERR(rc->data_inode);
+		btrfs_err(fs_info, "failed to create relocate inode: %d(%s)",
+			  err, btrfs_decode_error(err));
 		rc->data_inode = NULL;
 		goto out;
 	}
@@ -4394,6 +4438,9 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
 			ret = btrfs_wait_ordered_range(rc->data_inode, 0,
 						       (u64)-1);
 			if (ret) {
+				btrfs_err(fs_info,
+					"failed to wait ordered range: %d(%s)",
+					  ret, btrfs_decode_error(ret));
 				err = ret;
 				goto out;
 			}
@@ -4407,6 +4454,11 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
 	WARN_ON(rc->block_group->reserved > 0);
 	WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
 out:
+	if (err < 0)
+		btrfs_err(fs_info,
+			  "failed to relocate block group %llu: %d(%s)",
+			  rc->block_group->key.objectid, ret,
+			  btrfs_decode_error(ret));
 	if (err && rw)
 		btrfs_dec_block_group_ro(rc->block_group);
 	iput(rc->data_inode);
-- 
2.11.1




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2017-02-13  7:26 [PATCH] btrfs: relocation: Enhance kernel error output for relocation Qu Wenruo
2017-02-14  0:49 ` Liu Bo

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