On Mon, Oct 25, 2021 at 11:57 PM Jan Kara <jack@xxxxxxx> wrote: > > On Sat 23-10-21 10:06:24, Zhengyuan Liu wrote: > > On Fri, Oct 22, 2021 at 5:31 PM Jan Kara <jack@xxxxxxx> wrote: > > > > > > > Can you post output of "dumpe2fs -h <device>" for the filesystem where the > > > > > > > problem happens? Thanks! > > > > > > > > > > > > Sure, the output is: > > > > > > > > > > > > # dumpe2fs -h /dev/sda3 > > > > > > dumpe2fs 1.45.3 (14-Jul-2019) > > > > > > Filesystem volume name: <none> > > > > > > Last mounted on: /data > > > > > > Filesystem UUID: 09a51146-b325-48bb-be63-c9df539a90a1 > > > > > > Filesystem magic number: 0xEF53 > > > > > > Filesystem revision #: 1 (dynamic) > > > > > > Filesystem features: has_journal ext_attr resize_inode dir_index > > > > > > filetype needs_recovery sparse_super large_file > > > > > > > > > > Thanks for the data. OK, a filesystem without extents. Does your test by > > > > > any chance try to do direct IO to a hole in a file? Because that is not > > > > > (and never was) supported without extents. Also the fact that you don't see > > > > > the problem with ext4 (which means extents support) would be pointing in > > > > > that direction. > > > > > > > > I am not sure if it trys to do direct IO to a hole or not, is there any > > > > way to check? If you have a simple test to reproduce please let me know, > > > > we are glad to try. > > > > > > Can you enable following tracing? > > > > Sure, but let's confirm before doing that, it seems Ext4 doesn't > > support iomap in > > V4.19 which could also reproduce the problem, so if it is necessary to > > do the following > > tracing? or should we modify the tracing if under V4.19? > > Well, iomap is just a different generic framework for doing direct IO. The > fact that you can observe the problem both with iomap and the old direct IO > framework is one of the reasons why I think the problem is actually that > the file has holes (unallocated space in the middle). > > > > echo 1 >/sys/kernel/debug/tracing/events/ext4/ext4_ind_map_blocks_exit/enable > > > echo iomap_dio_rw >/sys/kernel/debug/tracing/set_ftrace_filter > > > echo "function_graph" >/sys/kernel/debug/tracing/current_tracer > > If you want to trace a kernel were ext4 direct IO path is not yet > converted to iomap framework you need to replace tracing of iomap_dio_rw > with: > > echo __blockdev_direct_IO >/sys/kernel/debug/tracing/set_ftrace_filter Sorry for the late reply, because it is hard to reproduce when enabling ftrace. I'll post here right after getting useful data. > > > And then gather output from /sys/kernel/debug/tracing/trace_pipe. Once the > > > problem reproduces, you can gather the problematic file name from dmesg, find > > > inode number from "stat <filename>" and provide that all to me? Thanks! >
