1 .. SPDX-License-Identifier: GPL-2.0 2 3 bcachefs private error codes 4 ---------------------------- 5 6 In bcachefs, as a hard rule we do not throw or directly use standard error 7 codes (-EINVAL, -EBUSY, etc.). Instead, we define private error codes as needed 8 in fs/bcachefs/errcode.h. 9 10 This gives us much better error messages and makes debugging much easier. Any 11 direct uses of standard error codes you see in the source code are simply old 12 code that has yet to be converted - feel free to clean it up! 13 14 Private error codes may subtype another error code, this allows for grouping of 15 related errors that should be handled similarly (e.g. transaction restart 16 errors), as well as specifying which standard error code should be returned at 17 the bcachefs module boundary. 18 19 At the module boundary, we use bch2_err_class() to convert to a standard error 20 code; this also emits a trace event so that the original error code be 21 recovered even if it wasn't logged. 22 23 Do not reuse error codes! Generally speaking, a private error code should only 24 be thrown in one place. That means that when we see it in a log message we can 25 see, unambiguously, exactly which file and line number it was returned from. 26 27 Try to give error codes names that are as reasonably descriptive of the error 28 as possible. Frequently, the error will be logged at a place far removed from 29 where the error was generated; good names for error codes mean much more 30 descriptive and useful error messages.
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