Hi, btrfs-profiler (https://github.com/adam900710/btrfs-profiler) has added a new tool: inject.py.
The tool is mostly a blend between bcc/tools/inject.py and Josef's
debug-scripts/inject-error.py:
- Variable length callchain (trigger) support
This feature is mostly from bcc.
With this tool, we can inject error for certain call stack.
E.g. to only trigger error for the following call trace in tree block
write path:
-C \
"btree_submit_bio_hook:btree_csum_one_bio:btrfs_check_leaf_full".
- Any target function support
This feature is mostly from Josef's script.
Unlike the limited target from bcc/inject, as long as the target
function is declared by ALLOW_ERROR_INJECTION(), it can be the target.
E.g. to inject error for btrfs_check_leaf_full():
"btrfs_check_leaf_full(struct extent_buffer *eb):-EUCLEAN"
- Extra condition to check before triggering error
This feature is mostly from bcc.
And this support custom parameters like above tree-checker parameters.
This allows us to filter certain calls before triggering error:
E.g. Don't inject error for __GFP_NOFAIL calls:
-F "!(gfpflags & __GFP_NOFAIL)"
Some misc features:
- Easier to edit C files
Unlike bcc tool which generate the C file, making the C code
fragmented and hard to read, this tool replaces placeholder inside
a complete C file, thus C part is easier to read.
- Easier to understand parameters
Good examples (although with poor English) for each option.
Limitation:
- No support for recursive callchain support
If the target get called recursively, callchain check is unreliable
and skipped.
Please use -F for such use case to filter out unwanted calls.
- Callchain sequence check for lower level is unreliable
Thus "func_a():func_b():func_c()" is the same as
"func_a():func_c():func_b()".
Normally two level callchain should be good enough(TM).
Thanks,
Qu
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