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Commit ddfae63c authored by Josef Bacik's avatar Josef Bacik Committed by David Sterba
Browse files

btrfs: move btrfs_truncate_block out of trans handle 



Since we do a delalloc reserve in btrfs_truncate_block we can deadlock
with freeze.  If somebody else is trying to allocate metadata for this
inode and it gets stuck in start_delalloc_inodes because of freeze we
will deadlock.  Be safe and move this outside of a trans handle.  This
also has a side-effect of making sure that we're not leaving stale data
behind in the other_encoding or encryption case.  Not an issue now since
nobody uses it, but it would be a problem in the future.

Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ce8ea7cc

fs/btrfs/inode.c

+45 −75
Original line number Diff line number Diff line
@@ -4360,47 +4360,11 @@ static int truncate_space_check(struct btrfs_trans_handle *trans, 


}



static int truncate_inline_extent(struct inode *inode,

				  struct btrfs_path *path,

				  struct btrfs_key *found_key,

				  const u64 item_end,

				  const u64 new_size)

{

	struct extent_buffer *leaf = path->nodes[0];

	int slot = path->slots[0];

	struct btrfs_file_extent_item *fi;

	u32 size = (u32)(new_size - found_key->offset);

	struct btrfs_root *root = BTRFS_I(inode)->root;



	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);



	if (btrfs_file_extent_compression(leaf, fi) != BTRFS_COMPRESS_NONE) {

		loff_t offset = new_size;

		loff_t page_end = ALIGN(offset, PAGE_SIZE);



/*

		 * Zero out the remaining of the last page of our inline extent,

		 * instead of directly truncating our inline extent here - that

		 * would be much more complex (decompressing all the data, then

		 * compressing the truncated data, which might be bigger than

		 * the size of the inline extent, resize the extent, etc).

		 * We release the path because to get the page we might need to

		 * read the extent item from disk (data not in the page cache).

 * Return this if we need to call truncate_block for the last bit of the

 * truncate.

 */

		btrfs_release_path(path);

		return btrfs_truncate_block(inode, offset, page_end - offset,

					0);

	}



	btrfs_set_file_extent_ram_bytes(leaf, fi, size);

	size = btrfs_file_extent_calc_inline_size(size);

	btrfs_truncate_item(root->fs_info, path, size, 1);



	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state))

		inode_sub_bytes(inode, item_end + 1 - new_size);



	return 0;

}

#define NEED_TRUNCATE_BLOCK 1



/*

 * this can truncate away extent items, csum items and directory items.
@@ -4561,11 +4525,6 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans, 
		if (found_type != BTRFS_EXTENT_DATA_KEY)

			goto delete;



		if (del_item)

			last_size = found_key.offset;

		else

			last_size = new_size;



		if (extent_type != BTRFS_FILE_EXTENT_INLINE) {

			u64 num_dec;

			extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
@@ -4607,40 +4566,30 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans, 
			 */

			if (!del_item &&

			    btrfs_file_extent_encryption(leaf, fi) == 0 &&

			    btrfs_file_extent_other_encoding(leaf, fi) == 0) {

			    btrfs_file_extent_other_encoding(leaf, fi) == 0 &&

			    btrfs_file_extent_compression(leaf, fi) == 0) {

				u32 size = (u32)(new_size - found_key.offset);



				btrfs_set_file_extent_ram_bytes(leaf, fi, size);

				size = btrfs_file_extent_calc_inline_size(size);

				btrfs_truncate_item(root->fs_info, path, size, 1);

			} else if (!del_item) {

				/*

				 * Need to release path in order to truncate a

				 * compressed extent. So delete any accumulated

				 * extent items so far.

				 * We have to bail so the last_size is set to

				 * just before this extent.

				 */

				if (btrfs_file_extent_compression(leaf, fi) !=

				    BTRFS_COMPRESS_NONE && pending_del_nr) {

					err = btrfs_del_items(trans, root, path,

							      pending_del_slot,

							      pending_del_nr);

					if (err) {

						btrfs_abort_transaction(trans,

									err);

						goto error;

					}

					pending_del_nr = 0;

				err = NEED_TRUNCATE_BLOCK;

				break;

			}



				err = truncate_inline_extent(inode, path,

							     &found_key,

							     item_end,

							     new_size);

				if (err) {

					btrfs_abort_transaction(trans, err);

					goto error;

				}

			} else if (test_bit(BTRFS_ROOT_REF_COWS,

					    &root->state)) {

			if (test_bit(BTRFS_ROOT_REF_COWS, &root->state))

				inode_sub_bytes(inode, item_end + 1 - new_size);

		}

		}

delete:

		if (del_item)

			last_size = found_key.offset;

		else

			last_size = new_size;

		if (del_item) {

			if (!pending_del_nr) {

				/* no pending yet, add ourselves */
@@ -9338,12 +9287,12 @@ static int btrfs_truncate(struct inode *inode) 
		ret = btrfs_truncate_inode_items(trans, root, inode,

						 inode->i_size,

						 BTRFS_EXTENT_DATA_KEY);

		trans->block_rsv = &fs_info->trans_block_rsv;

		if (ret != -ENOSPC && ret != -EAGAIN) {

			err = ret;

			break;

		}



		trans->block_rsv = &fs_info->trans_block_rsv;

		ret = btrfs_update_inode(trans, root, inode);

		if (ret) {

			err = ret;
@@ -9367,6 +9316,27 @@ static int btrfs_truncate(struct inode *inode) 
		trans->block_rsv = rsv;

	}



	/*

	 * We can't call btrfs_truncate_block inside a trans handle as we could

	 * deadlock with freeze, if we got NEED_TRUNCATE_BLOCK then we know

	 * we've truncated everything except the last little bit, and can do

	 * btrfs_truncate_block and then update the disk_i_size.

	 */

	if (ret == NEED_TRUNCATE_BLOCK) {

		btrfs_end_transaction(trans);

		btrfs_btree_balance_dirty(fs_info);



		ret = btrfs_truncate_block(inode, inode->i_size, 0, 0);

		if (ret)

			goto out;

		trans = btrfs_start_transaction(root, 1);

		if (IS_ERR(trans)) {

			ret = PTR_ERR(trans);

			goto out;

		}

		btrfs_ordered_update_i_size(inode, inode->i_size, NULL);

	}



	if (ret == 0 && inode->i_nlink > 0) {

		trans->block_rsv = root->orphan_block_rsv;

		ret = btrfs_orphan_del(trans, BTRFS_I(inode));