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Commit 8233767a authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Chris Mason
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Btrfs: allocate extent state and check the result properly 



It doesn't allocate extent_state and check the result properly:
- in set_extent_bit, it doesn't allocate extent_state if the path is not
  allowed wait

- in clear_extent_bit, it doesn't check the result after atomic-ly allocate,
  we trigger BUG_ON() if it's fail

- if allocate fail, we trigger BUG_ON instead of returning -ENOMEM since
  the return value of clear_extent_bit() is ignored by many callers

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent b0839166

fs/btrfs/extent_io.c

+26 −8
Original line number Diff line number Diff line
@@ -439,6 +439,15 @@ static int clear_state_bit(struct extent_io_tree *tree, 
	return ret;

}



static struct extent_state *

alloc_extent_state_atomic(struct extent_state *prealloc)

{

	if (!prealloc)

		prealloc = alloc_extent_state(GFP_ATOMIC);



	return prealloc;

}



/*

 * clear some bits on a range in the tree.  This may require splitting

 * or inserting elements in the tree, so the gfp mask is used to
@@ -476,8 +485,7 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
again:

	if (!prealloc && (mask & __GFP_WAIT)) {

		prealloc = alloc_extent_state(mask);

		if (!prealloc)

			return -ENOMEM;

		BUG_ON(!prealloc);

	}



	spin_lock(&tree->lock);
@@ -529,8 +537,8 @@ hit_next: 
	 */



	if (state->start < start) {

		if (!prealloc)

			prealloc = alloc_extent_state(GFP_ATOMIC);

		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

		err = split_state(tree, state, prealloc, start);

		BUG_ON(err == -EEXIST);

		prealloc = NULL;
@@ -551,8 +559,8 @@ hit_next: 
	 * on the first half

	 */

	if (state->start <= end && state->end > end) {

		if (!prealloc)

			prealloc = alloc_extent_state(GFP_ATOMIC);

		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

		err = split_state(tree, state, prealloc, end + 1);

		BUG_ON(err == -EEXIST);

		if (wake)
@@ -725,8 +733,7 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
again:

	if (!prealloc && (mask & __GFP_WAIT)) {

		prealloc = alloc_extent_state(mask);

		if (!prealloc)

			return -ENOMEM;

		BUG_ON(!prealloc);

	}



	spin_lock(&tree->lock);
@@ -743,6 +750,8 @@ again: 
	 */

	node = tree_search(tree, start);

	if (!node) {

		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

		err = insert_state(tree, prealloc, start, end, &bits);

		prealloc = NULL;

		BUG_ON(err == -EEXIST);
@@ -811,6 +820,9 @@ hit_next: 
			err = -EEXIST;

			goto out;

		}



		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

		err = split_state(tree, state, prealloc, start);

		BUG_ON(err == -EEXIST);

		prealloc = NULL;
@@ -841,6 +853,9 @@ hit_next: 
			this_end = end;

		else

			this_end = last_start - 1;



		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

		err = insert_state(tree, prealloc, start, this_end,

				   &bits);

		BUG_ON(err == -EEXIST);
@@ -865,6 +880,9 @@ hit_next: 
			err = -EEXIST;

			goto out;

		}



		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

		err = split_state(tree, state, prealloc, end + 1);

		BUG_ON(err == -EEXIST);