From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Mon, 10 Mar 2008 18:04:25 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with SMTP id m2B13xV2031888 for ; Mon, 10 Mar 2008 18:04:03 -0700 Date: Tue, 11 Mar 2008 12:04:21 +1100 From: David Chinner Subject: [Review] Improve XFS error checking and propagation Message-ID: <20080311010420.GD155407@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: xfs-dev Cc: xfs@oss.sgi.com, haryadi@cs.wisc.edu, remzi@cs.wisc.edu A recent paper at the FAST08 conference highlighted a large number of unchecked error paths in Linux filesystems and I/O layers. As a subsystem, XFS had the highest aggregate numbers of bad error propagation. A tarball which contains a quilt patch series of 32 patches aimed at improving this situation can be found here: http://oss.sgi.com/~dgc/xfs/error-check/xfs-error-checking.tar.gz The paper "EIO: Error Handling is Occasionally Correct" can be found here: http://www.cs.wisc.edu/adsl/Publications/eio-fast08.html And the in depth results here: http://www.cs.wisc.edu/adsl/Publications/eio-fast08/readme.html http://www.cs.wisc.edu/adsl/Publications/eio-fast08/ The XFS results I've been working from are here: http://www.cs.wisc.edu/adsl/Publications/eio-fast08/fullfs-xfs-without-false-positives.txt and included below is an annotated version of this file as I've worked through it. The graph of the XFS error paths is a good visual representation of how the bad error paths tend to cluster together: http://www.cs.wisc.edu/adsl/Publications/eio-fast08/singlefs-xfs.pdf (you'll need at least 800% zoom to be able to read it at all) The paper analysed a 2.6.15 kernel, but I've been working against an xfs-dev tree (~2.6.24). Of the 101 reported problems for the 2.6.15 kernel that was analysed: - 7 did not exist anymore (bhv layer, dirv1, write path changes) - 11 were false positives that were not modified - 24 were false positives that have been patched to remove (e.g. int xfs_foo() to void xfs_foo()) - 37 real problems where an error needed to be returned and are fixed in the patch series. - 3 where there is no error path to return an error and no point in even warning about it (ENOSPC flushing) - 10 where there is no error path to return an error, but patched to warn to the syslog about potential data loss or metadata I/O errors - 4 were already fixed in the xfs-dev tree - 2 where the error is ignored because we must continue anyway (patched to warn to syslog) - 4 that I haven't yet fixed (xfs_buf_iostrategy and xfs_buf_iostart) because I need to think about them more. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group ---------------------------------------- fs/xfs/ ---- d 1 xfs_write -> _xfs_log_force fs/xfs/linux-2.6/xfs_lrw.c 881 d 2 xfs_write -> _xfs_log_force fs/xfs/linux-2.6/xfs_lrw.c 884 F 3 xfs_flush_device -> _xfs_log_force fs/xfs/linux-2.6/xfs_super.c 547 F 4 xfs_qm_dqflush -> _xfs_log_force fs/xfs/quota/xfs_dquot.c 1294 F 5 xfs_qm_dqflock_pushbuf_wait -> _xfs_log_force fs/xfs/quota/xfs_dquot.c 1591 F 6 xfs_qm_dqunpin_wait -> _xfs_log_force fs/xfs/quota/xfs_dquot_item.c 204 F 7 xfs_qm_dquot_logitem_pushbuf -> _xfs_log_force fs/xfs/quota/xfs_dquot_item.c 267 F 8 xfs_alloc_search_busy -> _xfs_log_force fs/xfs/xfs_alloc.c 2593 F 9 xfs_iunpin_wait -> _xfs_log_force fs/xfs/xfs_inode.c 2847 F 10 xfs_iflush -> _xfs_log_force fs/xfs/xfs_inode.c 3243 F 11 xfs_inode_item_pushbuf -> _xfs_log_force fs/xfs/xfs_inode_item.c 819 P 12 xfs_log_unmount_write -> _xfs_log_force fs/xfs/xfs_log.c 529 F 13 xlog_recover_finish -> _xfs_log_force fs/xfs/xfs_log_recover.c 3961 F 14 xfs_unmountfs -> _xfs_log_force fs/xfs/xfs_mount.c 1088 F 15 xfs_trans_push_ail -> _xfs_log_force fs/xfs/xfs_trans_ail.c 198 F 16 xfs_syncsub -> _xfs_log_force fs/xfs/xfs_vfsops.c 1440 F 17 xfs_syncsub -> _xfs_log_force fs/xfs/xfs_vfsops.c 1455 F 18 xfs_syncsub -> _xfs_log_force fs/xfs/xfs_vfsops.c 1491 F 19 xfs_syncsub -> _xfs_log_force fs/xfs/xfs_vfsops.c 1543 P 20 xfs_fsync -> _xfs_log_force fs/xfs/xfs_vnodeops.c 1129 P 21 xfs_qm_write_sb_changes -> _xfs_trans_commit fs/xfs/quota/xfs_qm.c 2414 P 22 xfs_qm_scall_setqlim -> _xfs_trans_commit fs/xfs/quota/xfs_qm_syscalls.c 739 P 23 xfs_itruncate_finish -> _xfs_trans_commit fs/xfs/xfs_inode.c 1718 P 24 xlog_recover_process_efi -> _xfs_trans_commit fs/xfs/xfs_log_recover.c 3047 P 25 xlog_recover_clear_agi_bucket -> _xfs_trans_commit fs/xfs/xfs_log_recover.c 3174 PB 26 xfs_mount_log_sbunit -> _xfs_trans_commit fs/xfs/xfs_mount.c 1579 P 27 xfs_growfs_rt_alloc -> _xfs_trans_commit fs/xfs/xfs_rtalloc.c 154 P 28 xfs_growfs_rt_alloc -> _xfs_trans_commit fs/xfs/xfs_rtalloc.c 191 P 29 xfs_growfs_rt -> _xfs_trans_commit fs/xfs/xfs_rtalloc.c 2103 P 30 xfs_inactive_attrs -> _xfs_trans_commit fs/xfs/xfs_vnodeops.c 1505 C 31 xfs_inactive -> _xfs_trans_commit fs/xfs/xfs_vnodeops.c 1790 d 32 xfs_initialize_vnode -> bhv_insert fs/xfs/linux-2.6/xfs_super.c 220 d 33 vfs_insertops -> bhv_insert fs/xfs/linux-2.6/xfs_vfs.c 259 N 34 linvfs_truncate -> block_truncate_page fs/xfs/linux-2.6/xfs_iops.c 651 G 35 fs_flushinval_pages -> filemap_fdatawait fs/xfs/linux-2.6/xfs_fs_subr.c 83 G 36 fs_flush_pages -> filemap_fdatawait fs/xfs/linux-2.6/xfs_fs_subr.c 108 G 37 fs_flushinval_pages -> filemap_fdatawrite fs/xfs/linux-2.6/xfs_fs_subr.c 82 G 38 fs_flush_pages -> filemap_fdatawrite fs/xfs/linux-2.6/xfs_fs_subr.c 105 n 39 xfs_flush_inode_work -> filemap_flush fs/xfs/linux-2.6/xfs_super.c 508 PM 40 xlog_sync -> pagebuf_associate_memory fs/xfs/xfs_log.c 1358 PM 41 xlog_sync -> pagebuf_associate_memory fs/xfs/xfs_log.c 1395 PM 42 xlog_write_log_records -> pagebuf_associate_memory fs/xfs/xfs_log_recover.c 1156 PM 43 xlog_write_log_records -> pagebuf_associate_memory fs/xfs/xfs_log_recover.c 1159 PM 44 xlog_do_recovery_pass -> pagebuf_associate_memory fs/xfs/xfs_log_recover.c 3646 PM 45 xlog_do_recovery_pass -> pagebuf_associate_memory fs/xfs/xfs_log_recover.c 3653 PM 46 xlog_do_recovery_pass -> pagebuf_associate_memory fs/xfs/xfs_log_recover.c 3705 PM 47 xlog_do_recovery_pass -> pagebuf_associate_memory fs/xfs/xfs_log_recover.c 3711 M 48 xfs_buf_read_flags -> pagebuf_iostart fs/xfs/linux-2.6/xfs_buf.c 636 M 49 xfsbufd -> pagebuf_iostrategy fs/xfs/linux-2.6/xfs_buf.c 1755 M 50 xfs_flush_buftarg -> pagebuf_iostrategy fs/xfs/linux-2.6/xfs_buf.c 1816 M 51 XFS_bwrite -> pagebuf_iostrategy fs/xfs/linux-2.6/xfs_buf.h 503 n 52 xfs_flush_device_work -> sync_blockdev fs/xfs/linux-2.6/xfs_super.c 533 f 53 exit_xfs_fs -> unregister_filesystem fs/xfs/linux-2.6/xfs_super.c 999 PM 54 xfs_acl_vset -> xfs_acl_vremove fs/xfs/xfs_acl.c 326 f 55 xfs_ialloc_ag_select -> xfs_alloc_pagf_init fs/xfs/xfs_ialloc.c 411 P 56 xfs_qm_dqflush -> xfs_bawrite fs/xfs/quota/xfs_dquot.c 1300 N 57 xfs_qm_dqflock_pushbuf_wait -> xfs_bawrite fs/xfs/quota/xfs_dquot.c 1595 N 58 xfs_qm_dquot_logitem_pushbuf -> xfs_bawrite fs/xfs/quota/xfs_dquot_item.c 275 N 59 xfs_buf_item_push -> xfs_bawrite fs/xfs/xfs_buf_item.c 669 P 60 xfs_iflush -> xfs_bawrite fs/xfs/xfs_inode.c 3249 N 61 xfs_inode_item_pushbuf -> xfs_bawrite fs/xfs/xfs_inode_item.c 823 F 62 xfs_qm_dqflush -> xfs_bdwrite fs/xfs/quota/xfs_dquot.c 1298 F 63 xfs_qm_dqiter_bufs -> xfs_bdwrite fs/xfs/quota/xfs_qm.c 1551 F 64 xfs_iflush -> xfs_bdwrite fs/xfs/xfs_inode.c 3247 F 65 xlog_recover_do_buffer_trans -> xfs_bdwrite fs/xfs/xfs_log_recover.c 2271 F 66 xlog_recover_do_inode_trans -> xfs_bdwrite fs/xfs/xfs_log_recover.c 2535 F 67 xlog_recover_do_dquot_trans -> xfs_bdwrite fs/xfs/xfs_log_recover.c 2664 C 68 xfs_inactive -> xfs_bmap_finish fs/xfs/xfs_vnodeops.c 1788 P 69 xfs_iomap_write_allocate -> xfs_bmap_last_offset fs/xfs/xfs_iomap.c 787 d 70 xfs_dir_leaf_rebalance -> xfs_dir_leaf_compact fs/xfs/xfs_dir_leaf.c 1146 d 71 xfs_dir_leaf_rebalance -> xfs_dir_leaf_compact fs/xfs/xfs_dir_leaf.c 1176 d 72 xfs_dir_leaf_to_shortform -> xfs_dir_shortform_addname fs/xfs/xfs_dir_leaf.c 693 P 73 xlog_recover_process_efi -> xfs_free_extent fs/xfs/xfs_log_recover.c 3041 n 74 xfs_inode_item_push -> xfs_iflush fs/xfs/xfs_inode_item.c 879 P 75 xlog_recover_do_inode_trans -> xfs_imap fs/xfs/xfs_log_recover.c 2320 f 76 xfs_bmap_add_extent -> xfs_mod_incore_sb fs/xfs/xfs_bmap.c 689 f 77 xfs_bmap_add_extent_hole_delay -> xfs_mod_incore_sb fs/xfs/xfs_bmap.c 1918 f 78 xfs_bmap_del_extent -> xfs_mod_incore_sb fs/xfs/xfs_bmap.c 3117 f 79 xfs_bmapi -> xfs_mod_incore_sb fs/xfs/xfs_bmap.c 4801 f 80 xfs_bmapi -> xfs_mod_incore_sb fs/xfs/xfs_bmap.c 4805 f 81 xfs_bunmapi -> xfs_mod_incore_sb fs/xfs/xfs_bmap.c 5452 f 82 xfs_bunmapi -> xfs_mod_incore_sb fs/xfs/xfs_bmap.c 5458 f 83 xfs_trans_reserve -> xfs_mod_incore_sb fs/xfs/xfs_trans.c 305 P 84 xfs_qm_quotacheck -> xfs_mount_reset_sbqflags fs/xfs/quota/xfs_qm.c 1962 N 85 xfs_qm_dqpurge -> xfs_qm_dqflush fs/xfs/quota/xfs_dquot.c 1505 NB 86 xfs_qm_dquot_logitem_push -> xfs_qm_dqflush fs/xfs/quota/xfs_dquot_item.c 168 N 87 xfs_qm_shake_freelist -> xfs_qm_dqflush fs/xfs/quota/xfs_qm.c 2134 N 88 xfs_qm_dqreclaim_one -> xfs_qm_dqflush fs/xfs/quota/xfs_qm.c 2306 PM 89 xfs_qm_quotacheck -> xfs_qm_dqflush_all fs/xfs/quota/xfs_qm.c 1930 P 90 xfs_qm_scall_quotaoff -> xfs_qm_log_quotaoff fs/xfs/quota/xfs_qm_syscalls.c 291 P 91 xfs_qm_scall_quotaoff -> xfs_qm_log_quotaoff_end fs/xfs/quota/xfs_qm_syscalls.c 347 F 92 xfs_qm_newmount -> xfs_qm_mount_quotas fs/xfs/quota/xfs_qm_bhv.c 273 F 93 xfs_qm_endmount -> xfs_qm_mount_quotas fs/xfs/quota/xfs_qm_bhv.c 301 PM 94 xfs_quiesce_fs -> xfs_syncsub fs/xfs/xfs_vfsops.c 632 P 95 xlog_recover_process_efi -> xfs_trans_reserve fs/xfs/xfs_log_recover.c 3036 P 96 xlog_recover_clear_agi_bucket -> xfs_trans_reserve fs/xfs/xfs_log_recover.c 3152 P 97 xfs_qm_scall_trunc_qfiles -> xfs_truncate_file fs/xfs/quota/xfs_qm_syscalls.c 395 P 98 xfs_qm_scall_trunc_qfiles -> xfs_truncate_file fs/xfs/quota/xfs_qm_syscalls.c 404 P 99 xfs_log_unmount_write -> xlog_state_release_iclog fs/xfs/xfs_log.c 570 P 100 xfs_log_unmount_write -> xlog_state_release_iclog fs/xfs/xfs_log.c 606 f 101 xfs_log_force_umount -> xlog_state_sync_all fs/xfs/xfs_log.c 3586 f = false positive F = false positive + patch to remove condition G = patch in mainline git tree already M = __must_check annotations found this as well P = real, patch to fix n = no error path to return error N = no error path to return error, patch to warn about error added d = does not exist anymore. B = some other bug found and fixed at same time C = error ignored, must continue anyway. If silent, made noisy Notes: - all the xfs_mod_incore_sb() are false positive because they are freeing blocks or extents which means there can never be an error returned. The only error that can be returned is ENOSPC when trying to allocate blocks.... - none of the callers of xfs_mount_log_sb() check the return value. - new function xfs_log_sbcount failed to check return of xfs_trans_commit. Callers are failing to check return value. - most of the callers to xfs_log_force() are not interested in errors - they'll get them through other means (i.e. log error implies filesystem shutdown). Only a handful of callers really should return errors, such as fsync(), sync writes or synchronous transaction commits.