[PATCH 0/8] btrfs: Error handling fixes

[PATCH 0/8] btrfs: Error handling fixes

[Mark Fasheh]

Hi,

The following are assorted fixes to error handling from all parts of the
Btrfs code.  Every patch in this series stands on it's own, with the
exception of the last patch which relies on the one before it (so patches 7
and 8 can be considered a pair).  I also included in this series an
uncommited patch from Tsutomu Itoh which was a better version of a patch I
had written. He should be cc'd on that mail.

For the most part, I'm still concentrating on eliminating sites where we
BUG_ON(ret) instead of bubbling errors up the stack. The patches were
tested using some simple file system commands and a background kernel build.

A git branch with these patches is available:

git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/btrfs-error-handling.git for_mason


Thanks,
	--Mark

[PATCH 1/8] btrfs: Don't BUG_ON errors from btrfs_create_subvol_root()

[Mark Fasheh]

From: Mark Fasheh <mfasheh@suse.com>

This is called from only one place - create_subvol() which passes errors
safely back out to it's caller, btrfs_mksubvol where they are handled.

Additionally, btrfs_create_subvol_root() itself bug's needlessly from error
return of btrfs_update_inode(). Since create_subvol() was fixed to catch
errors we can bubble this one up too.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
---
 fs/btrfs/inode.c |    3 +--
 fs/btrfs/ioctl.c |    2 ++
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 15fceef..7028c0c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6722,10 +6722,9 @@ int btrfs_create_subvol_root(struct btrfs_trans_handle *trans,
 	btrfs_i_size_write(inode, 0);
 
 	err = btrfs_update_inode(trans, new_root, inode);
-	BUG_ON(err);
 
 	iput(inode);
-	return 0;
+	return err;
 }
 
 struct inode *btrfs_alloc_inode(struct super_block *sb)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 7cf0133..b3440f5 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -411,6 +411,8 @@ static noinline int create_subvol(struct btrfs_root *root,
 	btrfs_record_root_in_trans(trans, new_root);
 
 	ret = btrfs_create_subvol_root(trans, new_root, new_dirid);
+	if (ret)
+		goto fail;
 	/*
 	 * insert the directory item
 	 */
-- 
1.7.6

[PATCH 2/8] btrfs: Don't BUG_ON() errors in update_ref_for_cow()

[Mark Fasheh]

From: Mark Fasheh <mfasheh@suse.com>

The only caller of update_ref_for_cow() is __btrfs_cow_block() which was
originally ignoring any return values. update_ref_for_cow() however doesn't
look like a candidate to become a void function - there are a few places
where errors can occur.

So instead I changed update_ref_for_cow() to bubble all errors up (instead
of BUG_ON). __btrfs_cow_block() was then updated to catch and BUG_ON() any
errors from update_ref_for_cow(). The end effect is that we have no change
in behavior, but about 8 different places where a BUG_ON(ret) was removed.

Obviously a future patch will have to address the BUG_ON() in
__btrfs_cow_block().

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/btrfs/ctree.c |   31 +++++++++++++++++++++----------
 1 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 011cab3..5064930 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -331,7 +331,8 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 	if (btrfs_block_can_be_shared(root, buf)) {
 		ret = btrfs_lookup_extent_info(trans, root, buf->start,
 					       buf->len, &refs, &flags);
-		BUG_ON(ret);
+		if (ret)
+			return ret;
 		BUG_ON(refs == 0);
 	} else {
 		refs = 1;
@@ -351,14 +352,18 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 		     root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 		    !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 			ret = btrfs_inc_ref(trans, root, buf, 1);
-			BUG_ON(ret);
+			if (ret)
+				return ret;
 
 			if (root->root_key.objectid ==
 			    BTRFS_TREE_RELOC_OBJECTID) {
 				ret = btrfs_dec_ref(trans, root, buf, 0);
-				BUG_ON(ret);
+				if (ret)
+					return ret;
+
 				ret = btrfs_inc_ref(trans, root, cow, 1);
-				BUG_ON(ret);
+				if (ret)
+					return ret;
 			}
 			new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 		} else {
@@ -368,14 +373,16 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 				ret = btrfs_inc_ref(trans, root, cow, 1);
 			else
 				ret = btrfs_inc_ref(trans, root, cow, 0);
-			BUG_ON(ret);
+			if (ret)
+				return ret;
 		}
 		if (new_flags != 0) {
 			ret = btrfs_set_disk_extent_flags(trans, root,
 							  buf->start,
 							  buf->len,
 							  new_flags, 0);
-			BUG_ON(ret);
+			if (ret)
+				return ret;
 		}
 	} else {
 		if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
@@ -384,9 +391,12 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 				ret = btrfs_inc_ref(trans, root, cow, 1);
 			else
 				ret = btrfs_inc_ref(trans, root, cow, 0);
-			BUG_ON(ret);
+			if (ret)
+				return ret;
+
 			ret = btrfs_dec_ref(trans, root, buf, 1);
-			BUG_ON(ret);
+			if (ret)
+				return ret;
 		}
 		clean_tree_block(trans, root, buf);
 		*last_ref = 1;
@@ -415,7 +425,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_disk_key disk_key;
 	struct extent_buffer *cow;
-	int level;
+	int level, ret;
 	int last_ref = 0;
 	int unlock_orig = 0;
 	u64 parent_start;
@@ -467,7 +477,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 			    (unsigned long)btrfs_header_fsid(cow),
 			    BTRFS_FSID_SIZE);
 
-	update_ref_for_cow(trans, root, buf, cow, &last_ref);
+	ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
+	BUG_ON(ret);
 
 	if (root->ref_cows)
 		btrfs_reloc_cow_block(trans, root, buf, cow);
-- 
1.7.6

[PATCH 3/8] btrfs: Don't BUG_ON kzalloc error in btrfs_lookup_csums_range()

[Mark Fasheh]

From: Mark Fasheh <mfasheh@suse.com>

Unfortunately it isn't enough to just exit here - the kzalloc() happens in a
loop and the allocated items are added to a linked list whose head is passed
in from the caller.

To fix the BUG_ON() and also provide the semantic that the list passed in is
only modified on success, I create function-local temporary list that we add
items too. If no error is met, that list is spliced to the callers at the
end of the function. Otherwise the list will be walked and all items freed
before the error value is returned.

I did a simple test on this patch by forcing an error at the kzalloc() point
and verifying that when this hits (git clone seemed to exercise this), the
function throws the proper error. Unfortunately but predictably, we later
hit a BUG_ON(ret) type line that still hasn't been fixed up ;)

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
---
 fs/btrfs/file-item.c |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index b910694..679fbff 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -284,6 +284,7 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 	struct btrfs_ordered_sum *sums;
 	struct btrfs_sector_sum *sector_sum;
 	struct btrfs_csum_item *item;
+	LIST_HEAD(tmplist);
 	unsigned long offset;
 	int ret;
 	size_t size;
@@ -358,7 +359,10 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 					MAX_ORDERED_SUM_BYTES(root));
 			sums = kzalloc(btrfs_ordered_sum_size(root, size),
 					GFP_NOFS);
-			BUG_ON(!sums);
+			if (!sums) {
+				ret = -ENOMEM;
+				goto fail;
+			}
 
 			sector_sum = sums->sums;
 			sums->bytenr = start;
@@ -380,12 +384,19 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 				offset += csum_size;
 				sector_sum++;
 			}
-			list_add_tail(&sums->list, list);
+			list_add_tail(&sums->list, &tmplist);
 		}
 		path->slots[0]++;
 	}
 	ret = 0;
 fail:
+	while (ret < 0 && !list_empty(&tmplist)) {
+		sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
+		list_del(&sums->list);
+		kfree(sums);
+	}
+	list_splice_tail(&tmplist, list);
+
 	btrfs_free_path(path);
 	return ret;
 }
-- 
1.7.6

[PATCH 4/8] btrfs: make insert_ptr() void

[Mark Fasheh]

From: Mark Fasheh <mfasheh@suse.com>

insert_ptr() always returns zero, so all the exta error handling can go
away.  This makes it trivial to also make copy_for_split() a void function
as it's only return was from insert_ptr(). Finally, this all makes the
BUG_ON(ret) in split_leaf() meaningless so I removed that.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/btrfs/ctree.c |   59 ++++++++++++++++-------------------------------------
 1 files changed, 18 insertions(+), 41 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 5064930..84e4053e 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2134,12 +2134,10 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
  *
  * slot and level indicate where you want the key to go, and
  * blocknr is the block the key points to.
- *
- * returns zero on success and < 0 on any error
  */
-static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
-		      *root, struct btrfs_path *path, struct btrfs_disk_key
-		      *key, u64 bytenr, int slot, int level)
+static void insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
+		       *root, struct btrfs_path *path, struct btrfs_disk_key
+		       *key, u64 bytenr, int slot, int level)
 {
 	struct extent_buffer *lower;
 	int nritems;
@@ -2163,7 +2161,6 @@ static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
 	btrfs_set_node_ptr_generation(lower, slot, trans->transid);
 	btrfs_set_header_nritems(lower, nritems + 1);
 	btrfs_mark_buffer_dirty(lower);
-	return 0;
 }
 
 /*
@@ -2184,7 +2181,6 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
 	struct btrfs_disk_key disk_key;
 	int mid;
 	int ret;
-	int wret;
 	u32 c_nritems;
 
 	c = path->nodes[level];
@@ -2241,11 +2237,8 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
 	btrfs_mark_buffer_dirty(c);
 	btrfs_mark_buffer_dirty(split);
 
-	wret = insert_ptr(trans, root, path, &disk_key, split->start,
-			  path->slots[level + 1] + 1,
-			  level + 1);
-	if (wret)
-		ret = wret;
+	insert_ptr(trans, root, path, &disk_key, split->start,
+		   path->slots[level + 1] + 1, level + 1);
 
 	if (path->slots[level] >= mid) {
 		path->slots[level] -= mid;
@@ -2735,18 +2728,16 @@ out:
  *
  * returns 0 if all went well and < 0 on failure.
  */
-static noinline int copy_for_split(struct btrfs_trans_handle *trans,
-			       struct btrfs_root *root,
-			       struct btrfs_path *path,
-			       struct extent_buffer *l,
-			       struct extent_buffer *right,
-			       int slot, int mid, int nritems)
+static noinline void copy_for_split(struct btrfs_trans_handle *trans,
+				    struct btrfs_root *root,
+				    struct btrfs_path *path,
+				    struct extent_buffer *l,
+				    struct extent_buffer *right,
+				    int slot, int mid, int nritems)
 {
 	int data_copy_size;
 	int rt_data_off;
 	int i;
-	int ret = 0;
-	int wret;
 	struct btrfs_disk_key disk_key;
 
 	nritems = nritems - mid;
@@ -2774,12 +2765,9 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
 	}
 
 	btrfs_set_header_nritems(l, mid);
-	ret = 0;
 	btrfs_item_key(right, &disk_key, 0);
-	wret = insert_ptr(trans, root, path, &disk_key, right->start,
-			  path->slots[1] + 1, 1);
-	if (wret)
-		ret = wret;
+	insert_ptr(trans, root, path, &disk_key, right->start,
+		   path->slots[1] + 1, 1);
 
 	btrfs_mark_buffer_dirty(right);
 	btrfs_mark_buffer_dirty(l);
@@ -2797,8 +2785,6 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
 	}
 
 	BUG_ON(path->slots[0] < 0);
-
-	return ret;
 }
 
 /*
@@ -2987,12 +2973,8 @@ again:
 	if (split == 0) {
 		if (mid <= slot) {
 			btrfs_set_header_nritems(right, 0);
-			wret = insert_ptr(trans, root, path,
-					  &disk_key, right->start,
-					  path->slots[1] + 1, 1);
-			if (wret)
-				ret = wret;
-
+			insert_ptr(trans, root, path, &disk_key, right->start,
+				   path->slots[1] + 1, 1);
 			btrfs_tree_unlock(path->nodes[0]);
 			free_extent_buffer(path->nodes[0]);
 			path->nodes[0] = right;
@@ -3000,12 +2982,8 @@ again:
 			path->slots[1] += 1;
 		} else {
 			btrfs_set_header_nritems(right, 0);
-			wret = insert_ptr(trans, root, path,
-					  &disk_key,
-					  right->start,
-					  path->slots[1], 1);
-			if (wret)
-				ret = wret;
+			insert_ptr(trans, root, path, &disk_key, right->start,
+				   path->slots[1], 1);
 			btrfs_tree_unlock(path->nodes[0]);
 			free_extent_buffer(path->nodes[0]);
 			path->nodes[0] = right;
@@ -3021,8 +2999,7 @@ again:
 		return ret;
 	}
 
-	ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems);
-	BUG_ON(ret);
+	copy_for_split(trans, root, path, l, right, slot, mid, nritems);
 
 	if (split == 2) {
 		BUG_ON(num_doubles != 0);
-- 
1.7.6

[PATCH 5/8] btrfs: Don't BUG_ON errors in __finish_chunk_alloc()

[Mark Fasheh]

From: Mark Fasheh <mfasheh@suse.com>

All callers of __finish_chunk_alloc() BUG_ON() return value, so it's trivial
for us to always bubble up any errors caught in __finish_chunk_alloc() to be
caught there.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/btrfs/volumes.c |    7 ++-----
 1 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 53875ae..5d166c2 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2600,16 +2600,13 @@ static int __finish_chunk_alloc(struct btrfs_trans_handle *trans,
 	key.offset = chunk_offset;
 
 	ret = btrfs_insert_item(trans, chunk_root, &key, chunk, item_size);
-	BUG_ON(ret);
-
-	if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
+	if (ret == 0 && map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
 		ret = btrfs_add_system_chunk(trans, chunk_root, &key, chunk,
 					     item_size);
-		BUG_ON(ret);
 	}
 
 	kfree(chunk);
-	return 0;
+	return ret;
 }
 
 /*
-- 
1.7.6

[PATCH 6/8] btrfs: fix error check of btrfs_lookup_dentry()

[Mark Fasheh]

From: Tsutomu Itoh <t-itoh@jp.fujitsu.com>

Clean up btrfs_lookup_dentry() to never return NULL, but PTR_ERR(-ENOENT)
instead. This keeps the return value convention consistent.

Callers who pass to d_instatiate() require a trivial update.

create_snapshot() in particular looks like it can also lose a BUG_ON(!inode)
which is not really needed - there seems less harm in returning ENOENT to
userspace at that point in the stack than there is to crash the machine.

Mark: Fixed conflicts against latest tree, gave the patch a more thorough
description.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/btrfs/inode.c |   12 ++++++++++--
 fs/btrfs/ioctl.c |   11 +++++++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 7028c0c..9f3a85d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4027,7 +4027,7 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
 		return ERR_PTR(ret);
 
 	if (location.objectid == 0)
-		return NULL;
+		return ERR_PTR(-ENOENT);
 
 	if (location.type == BTRFS_INODE_ITEM_KEY) {
 		inode = btrfs_iget(dir->i_sb, &location, root, NULL);
@@ -4085,7 +4085,15 @@ static void btrfs_dentry_release(struct dentry *dentry)
 static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
 				   struct nameidata *nd)
 {
-	return d_splice_alias(btrfs_lookup_dentry(dir, dentry), dentry);
+	struct inode *inode = btrfs_lookup_dentry(dir, dentry);
+	if (IS_ERR(inode)) {
+		if (PTR_ERR(inode) == -ENOENT)
+			inode = NULL;
+		else
+			return ERR_CAST(inode);
+	}
+
+	return d_splice_alias(inode, dentry);
 }
 
 unsigned char btrfs_filetype_table[] = {
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b3440f5..692eac2 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -325,6 +325,7 @@ static noinline int create_subvol(struct btrfs_root *root,
 	struct btrfs_root *new_root;
 	struct dentry *parent = dentry->d_parent;
 	struct inode *dir;
+	struct inode *inode;
 	int ret;
 	int err;
 	u64 objectid;
@@ -435,7 +436,13 @@ static noinline int create_subvol(struct btrfs_root *root,
 
 	BUG_ON(ret);
 
-	d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
+	inode = btrfs_lookup_dentry(dir, dentry);
+	if (IS_ERR(inode)) {
+		ret = PTR_ERR(inode);
+		goto fail;
+	}
+
+	d_instantiate(dentry, inode);
 fail:
 	if (async_transid) {
 		*async_transid = trans->transid;
@@ -505,7 +512,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
 		ret = PTR_ERR(inode);
 		goto fail;
 	}
-	BUG_ON(!inode);
+
 	d_instantiate(dentry, inode);
 	ret = 0;
 fail:
-- 
1.7.6

[PATCH 7/8] btrfs: make fixup_low_keys() void

[Mark Fasheh]

From: Mark Fasheh <mfasheh@suse.com>

This is trivial - fixup_low_keys always returns zero so we can make it void.
As a result, we can then make setup_items_for_insert() void too which lets
us cut out a couple of BUG_ON(ret) lines.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/btrfs/ctree.c         |   59 ++++++++++++++-------------------------------
 fs/btrfs/ctree.h         |    8 +++---
 fs/btrfs/delayed-inode.c |    6 +---
 3 files changed, 25 insertions(+), 48 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 84e4053e..b42caec 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1874,16 +1874,12 @@ done:
  * This is used after shifting pointers to the left, so it stops
  * fixing up pointers when a given leaf/node is not in slot 0 of the
  * higher levels
- *
- * If this fails to write a tree block, it returns -1, but continues
- * fixing up the blocks in ram so the tree is consistent.
  */
-static int fixup_low_keys(struct btrfs_trans_handle *trans,
-			  struct btrfs_root *root, struct btrfs_path *path,
-			  struct btrfs_disk_key *key, int level)
+static void fixup_low_keys(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root, struct btrfs_path *path,
+			   struct btrfs_disk_key *key, int level)
 {
 	int i;
-	int ret = 0;
 	struct extent_buffer *t;
 
 	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
@@ -1896,7 +1892,6 @@ static int fixup_low_keys(struct btrfs_trans_handle *trans,
 		if (tslot != 0)
 			break;
 	}
-	return ret;
 }
 
 /*
@@ -2524,7 +2519,6 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
 	u32 old_left_nritems;
 	u32 nr;
 	int ret = 0;
-	int wret;
 	u32 this_item_size;
 	u32 old_left_item_size;
 
@@ -2630,9 +2624,7 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
 		clean_tree_block(trans, root, right);
 
 	btrfs_item_key(right, &disk_key, 0);
-	wret = fixup_low_keys(trans, root, path, &disk_key, 1);
-	if (wret)
-		ret = wret;
+	fixup_low_keys(trans, root, path, &disk_key, 1);
 
 	/* then fixup the leaf pointer in the path */
 	if (path->slots[0] < push_items) {
@@ -2988,12 +2980,8 @@ again:
 			free_extent_buffer(path->nodes[0]);
 			path->nodes[0] = right;
 			path->slots[0] = 0;
-			if (path->slots[1] == 0) {
-				wret = fixup_low_keys(trans, root,
-						path, &disk_key, 1);
-				if (wret)
-					ret = wret;
-			}
+			if (path->slots[1] == 0)
+				fixup_low_keys(trans, root, path, &disk_key, 1);
 		}
 		btrfs_mark_buffer_dirty(right);
 		return ret;
@@ -3209,10 +3197,9 @@ int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
 		return ret;
 
 	path->slots[0]++;
-	ret = setup_items_for_insert(trans, root, path, new_key, &item_size,
-				     item_size, item_size +
-				     sizeof(struct btrfs_item), 1);
-	BUG_ON(ret);
+	setup_items_for_insert(trans, root, path, new_key, &item_size,
+			       item_size, item_size +
+			       sizeof(struct btrfs_item), 1);
 
 	leaf = path->nodes[0];
 	memcpy_extent_buffer(leaf,
@@ -3515,7 +3502,7 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
 	ret = 0;
 	if (slot == 0) {
 		btrfs_cpu_key_to_disk(&disk_key, cpu_key);
-		ret = fixup_low_keys(trans, root, path, &disk_key, 1);
+		fixup_low_keys(trans, root, path, &disk_key, 1);
 	}
 
 	if (btrfs_leaf_free_space(root, leaf) < 0) {
@@ -3533,17 +3520,16 @@ out:
  * to save stack depth by doing the bulk of the work in a function
  * that doesn't call btrfs_search_slot
  */
-int setup_items_for_insert(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *root, struct btrfs_path *path,
-			   struct btrfs_key *cpu_key, u32 *data_size,
-			   u32 total_data, u32 total_size, int nr)
+void setup_items_for_insert(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root, struct btrfs_path *path,
+			    struct btrfs_key *cpu_key, u32 *data_size,
+			    u32 total_data, u32 total_size, int nr)
 {
 	struct btrfs_item *item;
 	int i;
 	u32 nritems;
 	unsigned int data_end;
 	struct btrfs_disk_key disk_key;
-	int ret;
 	struct extent_buffer *leaf;
 	int slot;
 
@@ -3604,10 +3590,9 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
 
 	btrfs_set_header_nritems(leaf, nritems + nr);
 
-	ret = 0;
 	if (slot == 0) {
 		btrfs_cpu_key_to_disk(&disk_key, cpu_key);
-		ret = fixup_low_keys(trans, root, path, &disk_key, 1);
+		fixup_low_keys(trans, root, path, &disk_key, 1);
 	}
 	btrfs_unlock_up_safe(path, 1);
 	btrfs_mark_buffer_dirty(leaf);
@@ -3616,7 +3601,6 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
 		btrfs_print_leaf(root, leaf);
 		BUG();
 	}
-	return ret;
 }
 
 /*
@@ -3648,7 +3632,8 @@ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
 	slot = path->slots[0];
 	BUG_ON(slot < 0);
 
-	ret = setup_items_for_insert(trans, root, path, cpu_key, data_size,
+	ret = 0;
+	setup_items_for_insert(trans, root, path, cpu_key, data_size,
 			       total_data, total_size, nr);
 
 out:
@@ -3694,7 +3679,6 @@ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 	struct extent_buffer *parent = path->nodes[level];
 	u32 nritems;
 	int ret = 0;
-	int wret;
 
 	nritems = btrfs_header_nritems(parent);
 	if (slot != nritems - 1) {
@@ -3714,9 +3698,7 @@ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		struct btrfs_disk_key disk_key;
 
 		btrfs_node_key(parent, &disk_key, 0);
-		wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
-		if (wret)
-			ret = wret;
+		fixup_low_keys(trans, root, path, &disk_key, level + 1);
 	}
 	btrfs_mark_buffer_dirty(parent);
 	return ret;
@@ -3819,10 +3801,7 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 			struct btrfs_disk_key disk_key;
 
 			btrfs_item_key(leaf, &disk_key, 0);
-			wret = fixup_low_keys(trans, root, path,
-					      &disk_key, 1);
-			if (wret)
-				ret = wret;
+			fixup_low_keys(trans, root, path, &disk_key, 1);
 		}
 
 		/* delete the leaf if it is mostly empty */
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0469263..d0b7b58 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2344,10 +2344,10 @@ static inline int btrfs_del_item(struct btrfs_trans_handle *trans,
 	return btrfs_del_items(trans, root, path, path->slots[0], 1);
 }
 
-int setup_items_for_insert(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *root, struct btrfs_path *path,
-			   struct btrfs_key *cpu_key, u32 *data_size,
-			   u32 total_data, u32 total_size, int nr);
+void setup_items_for_insert(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root, struct btrfs_path *path,
+			    struct btrfs_key *cpu_key, u32 *data_size,
+			    u32 total_data, u32 total_size, int nr);
 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
 		      *root, struct btrfs_key *key, void *data, u32 data_size);
 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index b52c672..6211997 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -738,10 +738,8 @@ static int btrfs_batch_insert_items(struct btrfs_trans_handle *trans,
 	btrfs_clear_path_blocking(path, NULL, 0);
 
 	/* insert the keys of the items */
-	ret = setup_items_for_insert(trans, root, path, keys, data_size,
-				     total_data_size, total_size, nitems);
-	if (ret)
-		goto error;
+	setup_items_for_insert(trans, root, path, keys, data_size,
+			       total_data_size, total_size, nitems);
 
 	/* insert the dir index items */
 	slot = path->slots[0];
-- 
1.7.6

[PATCH 8/8] btrfs: make del_ptr() and btrfs_del_leaf() void

[Mark Fasheh]

From: Mark Fasheh <mfasheh@suse.com>

Since fixup_low_keys() has been made void, del_ptr() always returns zero. We
can then make it void as well. This allows us in turn to make
btrfs_del_leaf() void as the only return value it was previously catching
was from del_ptr(). This winds up removing a couple of un-needed BUG_ON(ret)
lines.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/btrfs/ctree.c |   40 +++++++++++++---------------------------
 1 files changed, 13 insertions(+), 27 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index b42caec..32f8030 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -36,8 +36,8 @@ static int balance_node_right(struct btrfs_trans_handle *trans,
 			      struct btrfs_root *root,
 			      struct extent_buffer *dst_buf,
 			      struct extent_buffer *src_buf);
-static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-		   struct btrfs_path *path, int level, int slot);
+static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		    struct btrfs_path *path, int level, int slot);
 
 struct btrfs_path *btrfs_alloc_path(void)
 {
@@ -1005,10 +1005,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
 		if (btrfs_header_nritems(right) == 0) {
 			clean_tree_block(trans, root, right);
 			btrfs_tree_unlock(right);
-			wret = del_ptr(trans, root, path, level + 1, pslot +
-				       1);
-			if (wret)
-				ret = wret;
+			del_ptr(trans, root, path, level + 1, pslot + 1);
 			root_sub_used(root, right->len);
 			btrfs_free_tree_block(trans, root, right, 0, 1);
 			free_extent_buffer(right);
@@ -1046,9 +1043,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
 	if (btrfs_header_nritems(mid) == 0) {
 		clean_tree_block(trans, root, mid);
 		btrfs_tree_unlock(mid);
-		wret = del_ptr(trans, root, path, level + 1, pslot);
-		if (wret)
-			ret = wret;
+		del_ptr(trans, root, path, level + 1, pslot);
 		root_sub_used(root, mid->len);
 		btrfs_free_tree_block(trans, root, mid, 0, 1);
 		free_extent_buffer(mid);
@@ -3673,12 +3668,11 @@ int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
  * the tree should have been previously balanced so the deletion does not
  * empty a node.
  */
-static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-		   struct btrfs_path *path, int level, int slot)
+static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		    struct btrfs_path *path, int level, int slot)
 {
 	struct extent_buffer *parent = path->nodes[level];
 	u32 nritems;
-	int ret = 0;
 
 	nritems = btrfs_header_nritems(parent);
 	if (slot != nritems - 1) {
@@ -3701,7 +3695,6 @@ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		fixup_low_keys(trans, root, path, &disk_key, level + 1);
 	}
 	btrfs_mark_buffer_dirty(parent);
-	return ret;
 }
 
 /*
@@ -3714,17 +3707,13 @@ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  * The path must have already been setup for deleting the leaf, including
  * all the proper balancing.  path->nodes[1] must be locked.
  */
-static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
-				   struct btrfs_root *root,
-				   struct btrfs_path *path,
-				   struct extent_buffer *leaf)
+static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
+				    struct btrfs_root *root,
+				    struct btrfs_path *path,
+				    struct extent_buffer *leaf)
 {
-	int ret;
-
 	WARN_ON(btrfs_header_generation(leaf) != trans->transid);
-	ret = del_ptr(trans, root, path, 1, path->slots[1]);
-	if (ret)
-		return ret;
+	del_ptr(trans, root, path, 1, path->slots[1]);
 
 	/*
 	 * btrfs_free_extent is expensive, we want to make sure we
@@ -3735,7 +3724,6 @@ static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
 	root_sub_used(root, leaf->len);
 
 	btrfs_free_tree_block(trans, root, leaf, 0, 1);
-	return 0;
 }
 /*
  * delete the item at the leaf level in path.  If that empties
@@ -3792,8 +3780,7 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		} else {
 			btrfs_set_path_blocking(path);
 			clean_tree_block(trans, root, leaf);
-			ret = btrfs_del_leaf(trans, root, path, leaf);
-			BUG_ON(ret);
+			btrfs_del_leaf(trans, root, path, leaf);
 		}
 	} else {
 		int used = leaf_space_used(leaf, 0, nritems);
@@ -3829,8 +3816,7 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 
 			if (btrfs_header_nritems(leaf) == 0) {
 				path->slots[1] = slot;
-				ret = btrfs_del_leaf(trans, root, path, leaf);
-				BUG_ON(ret);
+				btrfs_del_leaf(trans, root, path, leaf);
 				free_extent_buffer(leaf);
 			} else {
 				/* if we're still in the path, make sure
-- 
1.7.6

[PATCH 0/8] btrfs: error handling fixes

[Qu Wenruo]

I believe there is a regression in the last 2 or 3 releases where
metadata/data space reservation code is no longer working properly,
result us to hit -ENOSPC during btrfs_run_delalloc_range().

One of the most common situation to hit such problem is during
generic/750, along with other long running generic tests.

Although I should start bisecting the space reservation bug, but I can
not help fixing the exposed bugs first.

This exposed quite some long existing bugs, all in the error handling
paths, that can lead to the following crashes

- Double ordered extent accounting
  Triggers WARN_ON_OCE() inside can_finish_ordered_extent() then crash.

  This bug is fixed by the first 3 patches.

- Subpage ASSERT() triggered, where subpage folio bitmap differs from
  folio status
  This happens most likey in submit_uncompressed_range(), where it
  unlock the folio without updating the subpage bitmaps.

  This bug is fixed by the 3rd patch.

- WARN_ON() if out-of-tree patch "btrfs: reject out-of-band dirty folios
  during writeback" applied
  This is a more complex case, where error handling leaves some folios
  dirty, but with EXTENT_DELALLOC flag cleared from extent io tree.

  Such dirty folios are still possible to be written back later, but
  since there is no EXTENT_DELALLOC flag, it will be treat as
  out-of-band dirty flags and trigger COW fixup.

  This bug is fixed by the 4th and 5th patch

With so many existing bugs exposed, there is more than enough motivation
to make btrfs_run_delalloc_range() (and its delalloc range functions)
output extra error messages so that at least we know something is wrong.

And those error messages have already helped a lot during my
development.

Patches 6~8 are here to enhance the error messages.

With all these patches applied, at least fstests can finish reliably,
otherwise it frequently crashes in generic tests that I was unable to
finish even one full run since the space reservation regression.

Qu Wenruo (8):
  btrfs: fix double accounting race when btrfs_run_delalloc_range()
    failed
  btrfs: fix double accounting race when extent_writepage_io() failed
  btrfs: fix the error handling of submit_uncompressed_range()
  btrfs: do proper folio cleanup when cow_file_range() failed
  btrfs: do proper folio cleanup when run_delalloc_nocow() failed
  btrfs: subpage: fix the bitmap dump for the locked flags
  btrfs: subpage: dump the involved bitmap when ASSERT() failed
  btrfs: add extra error messages for delalloc range related errors

 fs/btrfs/extent_io.c |  79 ++++++++++++++----
 fs/btrfs/inode.c     | 188 +++++++++++++++++++++++++++++++------------
 fs/btrfs/subpage.c   |  48 ++++++++---
 3 files changed, 234 insertions(+), 81 deletions(-)

-- 
2.47.1