Hi Jens I tried more on my side to debug the situation, and found a very weird write behavior: Some unexpected direct IO happened, without corresponding fsstress workload. The workload is: $fsstress -p 7 -n 50 -s 1691396493 -w -d $mnt -v > /tmp/fsstress Which I can reliably reproduce the problem locally, around 1/50 possibility. In my particular case, it results data corruption at root 5 inode 283 offset 8192. Then I added some trace points for the following functions: - btrfs_do_write_iter() Two trace points, one before btrfs_direct_write(), and one before btrfs_buffered_write(), outputting the aligned and unaligned write range, root/inode number, type of the write (buffered or direct). - btrfs_finish_one_ordered() This is where btrfs inserts its ordered extent into the subvolume tree. This happens when a range of pages finishes its writeback. Then here comes the fsstress log for inode 283 (no btrfs root number): 0/22: clonerange d0/f2[283 1 0 0 0 0] [0,0] -> d0/f2[283 1 0 0 0 0] [307200,0] 0/23: copyrange d0/f2[283 1 0 0 0 0] [0,0] -> d0/f2[283 1 0 0 0 0] [1058819,0] 0/25: write d0/f2[283 2 0 0 0 0] [393644,88327] 0 0/29: fallocate(INSERT_RANGE) d0/f3 [283 2 0 0 176 481971]t 884736 585728 95 0/30: uring_write d0/f3[283 2 0 0 176 481971] [1400622, 56456(res=56456)] 0 0/31: writev d0/f3[283 2 0 0 296 1457078] [709121,8,964] 0 0/33: do_aio_rw - xfsctl(XFS_IOC_DIOINFO) d0/f2[283 2 308134 1763236 320 1457078] return 25, fallback to stat() 0/34: dwrite - xfsctl(XFS_IOC_DIOINFO) d0/f3[283 2 308134 1763236 320 1457078] return 25, fallback to stat() 0/34: dwrite d0/f3[283 2 308134 1763236 320 1457078] [589824,16384] 0 0/38: dwrite - xfsctl(XFS_IOC_DIOINFO) d0/f3[283 2 308134 1763236 496 1457078] return 25, fallback to stat() 0/38: dwrite d0/f3[283 2 308134 1763236 496 1457078] [2084864,36864] 0 0/39: write d0/d4/f6[283 2 308134 1763236 496 2121728] [2749000,60139] 0 0/40: fallocate(ZERO_RANGE) d0/f3 [283 2 308134 1763236 688 2809139]t 3512660 81075 0 0/43: splice d0/f5[293 1 0 0 1872 2678784] [552619,59420] -> d0/f3[283 2 308134 1763236 856 3593735] [5603798,59420] 0 0/48: fallocate(KEEP_SIZE|PUNCH_HOLE) d0/f3 [283 1 308134 1763236 976 5663218]t 1361821 480392 0 0/49: clonerange d0/f3[283 1 308134 1763236 856 5663218] [2461696,53248] -> d0/f5[293 1 0 0 1872 2678784] [942080,53248] Note one thing, there is no direct/buffered write into inode 283 offset 8192. But from the trace events for root 5 inode 283: btrfs_do_write_iter: r/i=5/283 buffered fileoff=393216(393644) len=90112(88327) btrfs_do_write_iter: r/i=5/283 buffered fileoff=1396736(1400622) len=61440(56456) btrfs_do_write_iter: r/i=5/283 buffered fileoff=708608(709121) len=12288(7712) btrfs_do_write_iter: r/i=5/283 direct fileoff=8192(8192) len=73728(73728) <<<<< btrfs_do_write_iter: r/i=5/283 direct fileoff=589824(589824) len=16384(16384) btrfs_finish_one_ordered: r/i=5/283 fileoff=8192 len=73728 btrfs_finish_one_ordered: r/i=5/283 fileoff=589824 len=16384 btrfs_do_write_iter: r/i=5/283 direct fileoff=2084864(2084864) len=36864(36864) btrfs_finish_one_ordered: r/i=5/283 fileoff=2084864 len=36864 btrfs_do_write_iter: r/i=5/283 buffered fileoff=2748416(2749000) len=61440(60139) btrfs_do_write_iter: r/i=5/283 buffered fileoff=5603328(5603798) len=61440(59420) btrfs_finish_one_ordered: r/i=5/283 fileoff=393216 len=90112 btrfs_finish_one_ordered: r/i=5/283 fileoff=708608 len=12288 btrfs_finish_one_ordered: r/i=5/283 fileoff=1396736 len=61440 btrfs_finish_one_ordered: r/i=5/283 fileoff=3592192 len=4096 btrfs_finish_one_ordered: r/i=5/283 fileoff=2748416 len=61440 btrfs_finish_one_ordered: r/i=5/283 fileoff=5603328 len=61440 Note that phantom direct IO call, which is in the corrupted range. If paired with fsstress, that phantom write happens between the two operations: 0/31: writev d0/f3[283 2 0 0 296 1457078] [709121,8,964] 0 0/34: dwrite d0/f3[283 2 308134 1763236 320 1457078] [589824,16384] 0 I'll keep digging, but the phantom writes which is not properly loggeg from fsstress is already a concern to me. Or maybe I'm missing some fixes in fsstress? Thanks, Qu
