Hi forks, Sorry for long delay these days due to my work ineffective, this is RFC v2 of this patchset addressing previous constructive comments... This RFC patchset mainly addresses the thoughts [*] and [**] from Dave's original patchset, https://lore.kernel.org/r/20200623095015.1934171-1-david@xxxxxxxxxxxxx In short, it focues on the following ideas mentioned by Dave: - use bucket 0 instead of multiple buckets since in-memory double linked list finally works; - avoid taking AGI buffer and unnecessary AGI update if possible, so 1) add a new lock and keep proper locking order to avoid deadlock; 2) insert a new unlinked inode from the tail instead of head; In addition, it's worth noticing 3 things: - xfs_iunlink_remove() should support old multiple buckets in order to keep old inode unlinked list (old image) working when recovering. - (but) OTOH, the old kernel recovery _shouldn't_ work with new image since the bucket_index from old xfs_iunlink_remove() is generated by the old formula (rather than keep in xfs_inode), which is now fixed as 0. So this feature is not forward compatible without some extra backport patches; - a tail xfs_inode pointer is also added in the perag, which keeps track of the tail of bucket 0 since it's mainly used for xfs_iunlink(). - the old kernel recovery shouldn't work with new image since its bucket_index from old kernel is The git tree is also available at git://git.kernel.org/pub/scm/linux/kernel/git/xiang/linux.git tags/xfs/iunlink_opt_v2 Gitweb: https://git.kernel.org/pub/scm/linux/kernel/git/xiang/linux.git/log/?h=xfs/iunlink_opt_v2 Some limited test for debugging only is done (mainly fsstress and manual power-cut tests) and it's worth noticing that when I tested fsstress for much longer time, it showed the following kernel message twice and it haven't been reproduced again for about 3 days, and I have no idea what's wrong over the current logic, so it could be better to send out the patchset first and go on reproducing with extra debugging prints added... [ 7884.930106] XFS (sda): bad inode magic/vsn daddr 111232 #0 (magic=5050) [ 7884.930988] XFS (sda): Metadata corruption detected at xfs_buf_ioend+0x11a/0x190, xfs_inode block 0x1b280 xfs_inode_buf_verify [ 7884.932418] XFS (sda): Unmount and run xfs_repair [ 7884.933154] XFS (sda): First 128 bytes of corrupted metadata buffer: [ 7884.934253] 00000000: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.935495] 00000010: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.936752] 00000020: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.937761] 00000030: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.939336] 00000040: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.940914] 00000050: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.942382] 00000060: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.943513] 00000070: 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 PPPPPPPPPPPPPPPP [ 7884.945006] XFS (sda): metadata I/O error in "xfs_imap_to_bp+0x61/0xd0" at daddr 0x1b280 len 32 error 117 [ 7884.952066] XFS (sda): xfs_do_force_shutdown(0x1) called from line 312 of file fs/xfs/xfs_trans_buf.c. Return address = ffffffff983ea7e0 [ 7884.952494] sda: writeback error on inode 20695, offset 770048, sector 1970864 [ 7884.954353] XFS (sda): I/O Error Detected. Shutting down filesystem [ 7884.956566] sda: writeback error on inode 117946, offset 2347008, sector 612424 [ 7884.956802] XFS (sda): Please unmount the filesystem and rectify the problem(s) [ 7884.958943] XFS (sda): xfs_inactive_ifree: xfs_trans_commit returned error -117 fsstress: check_cwd failure [ 7884.963475] XFS (sda): xfs_imap_lookup: xfs_ialloc_read_agi() returned error -5, agno 0 Comments and directions are welcomed. :) Thanks, Gao Xiang Changes since v1: - show some number of reduced AGI buffer modification (Darrick); - add comments about pag_unlinked_mutex, pag_unlinked_tail (Darrick); - avoid touching xfs_iunlink_update_bucket() logic (Dave); - spilt "xfs: don't access AGI on unlinked inodes if it can" into 2 patches (Dave); - add xfs_iunlink_insert_lock/xfs_iunlink_remove_lock/xfs_iunlink_unlock to make the code easy to follow (Dave). Gao Xiang (3): xfs: arrange all unlinked inodes into one list xfs: introduce perag iunlink lock xfs: insert unlinked inodes from tail fs/xfs/xfs_inode.c | 202 ++++++++++++++++++++++++++++----------- fs/xfs/xfs_log_recover.c | 5 + fs/xfs/xfs_mount.c | 2 + fs/xfs/xfs_mount.h | 6 ++ 4 files changed, 159 insertions(+), 56 deletions(-) -- 2.18.1
