From: Dave Chinner dchinner@redhat.com
commit 56486f307100e8fc66efa2ebd8a71941fa10bf6f upstream.
xfs/538 on a 1kB block filesystem failed with this assert:
XFS: Assertion failed: cur->bc_btnum != XFS_BTNUM_BMAP || cur->bc_ino.allocated == 0 || xfs_is_shutdown(cur->bc_mp), file: fs/xfs/libxfs/xfs_btree.c, line: 448
The problem was that an allocation failed unexpectedly in xfs_bmbt_alloc_block() after roughly 150,000 minlen allocation error injections, resulting in an EFSCORRUPTED error being returned to xfs_bmapi_write(). The error occurred on extent-to-btree format conversion allocating the new root block:
RIP: 0010:xfs_bmbt_alloc_block+0x177/0x210 Call Trace: <TASK> xfs_btree_new_iroot+0xdf/0x520 xfs_btree_make_block_unfull+0x10d/0x1c0 xfs_btree_insrec+0x364/0x790 xfs_btree_insert+0xaa/0x210 xfs_bmap_add_extent_hole_real+0x1fe/0x9a0 xfs_bmapi_allocate+0x34c/0x420 xfs_bmapi_write+0x53c/0x9c0 xfs_alloc_file_space+0xee/0x320 xfs_file_fallocate+0x36b/0x450 vfs_fallocate+0x148/0x340 __x64_sys_fallocate+0x3c/0x70 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xa
Why the allocation failed at this point is unknown, but is likely that we ran the transaction out of reserved space and filesystem out of space with bmbt blocks because of all the minlen allocations being done causing worst case fragmentation of a large allocation.
Regardless of the cause, we've then called xfs_bmapi_finish() which calls xfs_btree_del_cursor(cur, error) to tear down the cursor.
So we have a failed operation, error != 0, cur->bc_ino.allocated > 0 and the filesystem is still up. The assert fails to take into account that allocation can fail with an error and the transaction teardown will shut the filesystem down if necessary. i.e. the assert needs to check "|| error != 0" as well, because at this point shutdown is pending because the current transaction is dirty....
Signed-off-by: Dave Chinner dchinner@redhat.com Reviewed-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Dave Chinner david@fromorbit.com Signed-off-by: Amir Goldstein amir73il@gmail.com --- fs/xfs/libxfs/xfs_btree.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c index 9f9f9feccbcd..98c82f4935e1 100644 --- a/fs/xfs/libxfs/xfs_btree.c +++ b/fs/xfs/libxfs/xfs_btree.c @@ -372,8 +372,14 @@ xfs_btree_del_cursor( break; }
+ /* + * If we are doing a BMBT update, the number of unaccounted blocks + * allocated during this cursor life time should be zero. If it's not + * zero, then we should be shut down or on our way to shutdown due to + * cancelling a dirty transaction on error. + */ ASSERT(cur->bc_btnum != XFS_BTNUM_BMAP || cur->bc_ino.allocated == 0 || - XFS_FORCED_SHUTDOWN(cur->bc_mp)); + XFS_FORCED_SHUTDOWN(cur->bc_mp) || error != 0); if (unlikely(cur->bc_flags & XFS_BTREE_STAGING)) kmem_free(cur->bc_ops); kmem_cache_free(xfs_btree_cur_zone, cur);