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Commit c2d904e0 authored by Jeff Mahoney's avatar Jeff Mahoney Committed by David Sterba
Browse files

btrfs: Catch locking failures in {set,clear,convert}_extent_bit 



The *_state functions can only return 0 or -EEXIST. This patch addresses
the cases where those functions returning -EEXIST represent a locking
failure. It handles them by panicking with an appropriate error message.

Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
parent 8c342930

fs/btrfs/extent_io.c

+38 −20
Original line number Diff line number Diff line
@@ -53,6 +53,12 @@ struct extent_page_data { 
	unsigned int sync_io:1;

};



static inline struct btrfs_fs_info *

tree_fs_info(struct extent_io_tree *tree)

{

	return btrfs_sb(tree->mapping->host->i_sb);

}



int __init extent_io_init(void)

{

	extent_state_cache = kmem_cache_create("extent_state",
@@ -439,6 +445,13 @@ alloc_extent_state_atomic(struct extent_state *prealloc) 
	return prealloc;

}



void extent_io_tree_panic(struct extent_io_tree *tree, int err)

{

	btrfs_panic(tree_fs_info(tree), err, "Locking error: "

		    "Extent tree was modified by another "

		    "thread while locked.");

}



/*

 * 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
@@ -542,7 +555,9 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

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

		BUG_ON(err == -EEXIST);

		if (err)

			extent_io_tree_panic(tree, err);



		prealloc = NULL;

		if (err)

			goto out;
@@ -564,7 +579,9 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

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

		BUG_ON(err == -EEXIST);

		if (err)

			extent_io_tree_panic(tree, err);



		if (wake)

			wake_up(&state->wq);
@@ -742,8 +759,10 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

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

		if (err)

			extent_io_tree_panic(tree, err);



		prealloc = NULL;

		BUG_ON(err == -EEXIST);

		goto out;

	}

	state = rb_entry(node, struct extent_state, rb_node);
@@ -809,7 +828,9 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

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

		BUG_ON(err == -EEXIST);

		if (err)

			extent_io_tree_panic(tree, err);



		prealloc = NULL;

		if (err)

			goto out;
@@ -846,12 +867,9 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		 */

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

				   &bits);

		BUG_ON(err == -EEXIST);

		if (err) {

			free_extent_state(prealloc);

			prealloc = NULL;

			goto out;

		}

		if (err)

			extent_io_tree_panic(tree, err);



		cache_state(prealloc, cached_state);

		prealloc = NULL;

		start = this_end + 1;
@@ -873,7 +891,8 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		prealloc = alloc_extent_state_atomic(prealloc);

		BUG_ON(!prealloc);

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

		BUG_ON(err == -EEXIST);

		if (err)

			extent_io_tree_panic(tree, err);



		set_state_bits(tree, prealloc, &bits);

		cache_state(prealloc, cached_state);
@@ -946,7 +965,8 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		}

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

		prealloc = NULL;

		BUG_ON(err == -EEXIST);

		if (err)

			extent_io_tree_panic(tree, err);

		goto out;

	}

	state = rb_entry(node, struct extent_state, rb_node);
@@ -1002,7 +1022,8 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
			goto out;

		}

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

		BUG_ON(err == -EEXIST);

		if (err)

			extent_io_tree_panic(tree, err);

		prealloc = NULL;

		if (err)

			goto out;
@@ -1041,12 +1062,8 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		 */

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

				   &bits);

		BUG_ON(err == -EEXIST);

		if (err) {

			free_extent_state(prealloc);

			prealloc = NULL;

			goto out;

		}

		if (err)

			extent_io_tree_panic(tree, err);

		prealloc = NULL;

		start = this_end + 1;

		goto search_again;
@@ -1065,7 +1082,8 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		}



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

		BUG_ON(err == -EEXIST);

		if (err)

			extent_io_tree_panic(tree, err);



		set_state_bits(tree, prealloc, &bits);

		clear_state_bit(tree, prealloc, &clear_bits, 0);