Re: [Crash-utility] [PATCH v3] diskdump: Add support for reading dumpfiles compressed by Zstandard

> --- a/diskdump.c > +++ b/diskdump.c > @@ -96,6 +96,10 @@ static struct diskdump_data **dd_list = NULL; > static int num_dd = 0; > static int num_dumpfiles = 0; > > +#ifdef ZSTD > +static ZSTD_DCtx *dctx = NULL; > +#endif > + Would it be better to move the above definition to cache_page()? Because it is not used in other functions, and the behavior is the same.

> int dumpfile_is_split(void) > { > return KDUMP_SPLIT(); > @@ -1001,6 +1005,9 @@ is_diskdump(char *file) > #ifdef SNAPPY > dd->flags |= SNAPPY_SUPPORTED; > #endif > +#ifdef ZSTD > + dd->flags |= ZSTD_SUPPORTED; > +#endif > > pc->read_vmcoreinfo = vmcoreinfo_read_string; > > @@ -1251,6 +1258,33 @@ cache_page(physaddr_t paddr) > ret); > return READ_ERROR; > } > +#endif > + } else if (pd.flags & DUMP_DH_COMPRESSED_ZSTD) { > + > + if (!(dd->flags & ZSTD_SUPPORTED)) { > + error(INFO, "%s: uncompess failed: no zstd compression support\n", > + DISKDUMP_VALID() ? "diskdump" : "compressed kdump"); > + return READ_ERROR; > + } > +#ifdef ZSTD > + if (!dctx) > + dctx = ZSTD_createDCtx(); > + Usually these two functions ZSTD_createDCtx()/ZSTC_free() are required to be called in pairs, but this(static definition) seems to simplify the code.