xfs: fix a memory leak in xfs_buf_item_init()

xfs_buf_item_get_format() may allocate memory for bip->bli_formats,
free the memory in the error path.

Fixes: c3d5f0c ("xfs: complain if anyone tries to create a too-large buffer log item")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Haoxiang Li

fs/xfs/xfs_buf_item.c

@@ -896,6 +896,7 @@ xfs_buf_item_init(
 		map_size = DIV_ROUND_UP(chunks, NBWORD);
 
 		if (map_size > XFS_BLF_DATAMAP_SIZE) {
+			xfs_buf_item_free_format(bip);
 			kmem_cache_free(xfs_buf_item_cache, bip);
 			xfs_err(mp,
 	"buffer item dirty bitmap (%u uints) too small to reflect %u bytes!",