[Crash-utility] [PATCH v2] diskdump: Add support for reading dumpfiles compressed by Zstandard
HAGIO KAZUHITO(萩尾 一仁)
k-hagio-ab at nec.com
Fri Sep 24 02:33:44 UTC 2021
Hi Philipp,
-----Original Message-----
>
> Hi Kazu,
>
> the patch follows the snappy and lzo example and all in all the
> looks good to me. Two small comments below though. Nevertheless
>
> Reviewed-by: Philipp Rudo <prudo at redhat.com>
Thanks for reviewing this!
>
>
> On Fri, 17 Sep 2021 07:55:32 +0000
> HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab at nec.com> wrote:
>
> > -----Original Message-----
> > > @@ -1002,6 +1006,11 @@ is_diskdump(char *file)
> > > dd->flags |= SNAPPY_SUPPORTED;
> > > #endif
> > >
> > > +#ifdef ZSTD
> > > + if ((dctx = ZSTD_createDCtx()) != NULL)
> > > + dd->flags |= ZSTD_SUPPORTED;
> >
> > I found that this part allocates dctx superfluously for split dumpfiles,
> > so sending v2.
> >
> > --
> > From: Kazuhito Hagio <k-hagio at ab.jp.nec.com>
> > Subject: [PATCH] diskdump: Add support for reading dumpfiles compressed by
> > Zstandard
> >
> > Add support for reading dumpfiles compressed by Zstandard (zstd)
> > using makedumpfile.
> >
> > To build crash with zstd support, type "make zstd".
> >
> > Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
> > ---
> > Makefile | 4 ++++
> > README | 4 ++--
> > configure.c | 20 +++++++++++++++++---
> > defs.h | 4 ++++
> > diskdump.c | 33 +++++++++++++++++++++++++++++++++
> > diskdump.h | 1 +
> > help.c | 4 ++--
> > 7 files changed, 63 insertions(+), 7 deletions(-)
>
> [...]
>
> > --- a/configure.c
> > +++ b/configure.c
> > @@ -1746,6 +1746,7 @@ add_extra_lib(char *option)
>
> You should probably add a 'For ZSTD:' section in the comment above this
> function as well.
Agree, will add in v3.
>
> > {
> > int lzo, add_DLZO, add_llzo2;
> > int snappy, add_DSNAPPY, add_lsnappy;
> > + int zstd, add_DZSTD, add_lzstd;
> > int valgrind, add_DVALGRIND;
> > char *cflags, *ldflags;
> > FILE *fp_cflags, *fp_ldflags;
>
> [...]
>
> > --- 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
> > +
> > int dumpfile_is_split(void)
> > {
> > return KDUMP_SPLIT();
> > @@ -1002,6 +1006,13 @@ is_diskdump(char *file)
> > dd->flags |= SNAPPY_SUPPORTED;
> > #endif
> >
> > +#ifdef ZSTD
> > + if (!dctx)
> > + dctx = ZSTD_createDCtx();
> > + if (dctx)
> > + dd->flags |= ZSTD_SUPPORTED;
> > +#endif
> > +
>
> would it make sense to only set ZSTD_SUPPORTED here and move the
> creation of dctx to cache_page where it is used? That at least would
> save a couple of bytes when zstd is supported but the dump is not zstd
> compressed.
Makes sense. This also will make an error distinguishable between
no zstd support or failure of ZSTD_createDCtx().
will post v3.
Thanks,
Kazu
>
> Thanks
> Philipp
>
> > pc->read_vmcoreinfo = vmcoreinfo_read_string;
> >
> > if ((pc->flags2 & GET_LOG) && KDUMP_CMPRS_VALID()) {
> > @@ -1251,6 +1262,24 @@ 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
> > + retlen = ZSTD_decompressDCtx(dctx,
> > + dd->page_cache_hdr[i].pg_bufptr, block_size,
> > + dd->compressed_page, pd.size);
> > + if (ZSTD_isError(retlen)) {
> > + error(INFO, "%s: uncompress failed: %d (%s)\n",
> > + DISKDUMP_VALID() ? "diskdump" : "compressed kdump",
> > + retlen, ZSTD_getErrorName(retlen));
> > + return READ_ERROR;
> > + }
> > #endif
> > } else
> > memcpy(dd->page_cache_hdr[i].pg_bufptr,
> > @@ -1806,6 +1835,8 @@ __diskdump_memory_dump(FILE *fp)
> > fprintf(fp, "%sLZO_SUPPORTED", others++ ? "|" : "");
> > if (dd->flags & SNAPPY_SUPPORTED)
> > fprintf(fp, "%sSNAPPY_SUPPORTED", others++ ? "|" : "");
> > + if (dd->flags & ZSTD_SUPPORTED)
> > + fprintf(fp, "%sZSTD_SUPPORTED", others++ ? "|" : "");
> > fprintf(fp, ") %s\n", FLAT_FORMAT() ? "[FLAT]" : "");
> > fprintf(fp, " dfd: %d\n", dd->dfd);
> > fprintf(fp, " ofp: %lx\n", (ulong)dd->ofp);
> > @@ -1872,6 +1903,8 @@ __diskdump_memory_dump(FILE *fp)
> > fprintf(fp, "DUMP_DH_COMPRESSED_LZO");
> > if (dh->status & DUMP_DH_COMPRESSED_SNAPPY)
> > fprintf(fp, "DUMP_DH_COMPRESSED_SNAPPY");
> > + if (dh->status & DUMP_DH_COMPRESSED_ZSTD)
> > + fprintf(fp, "DUMP_DH_COMPRESSED_ZSTD");
> > if (dh->status & DUMP_DH_COMPRESSED_INCOMPLETE)
> > fprintf(fp, "DUMP_DH_COMPRESSED_INCOMPLETE");
> > if (dh->status & DUMP_DH_EXCLUDED_VMEMMAP)
> > diff --git a/diskdump.h b/diskdump.h
> > index 28713407b841..c152c7b86616 100644
> > --- a/diskdump.h
> > +++ b/diskdump.h
> > @@ -86,6 +86,7 @@ struct kdump_sub_header {
> > #define DUMP_DH_COMPRESSED_SNAPPY 0x4 /* page is compressed with snappy */
> > #define DUMP_DH_COMPRESSED_INCOMPLETE 0x8 /* dumpfile is incomplete */
> > #define DUMP_DH_EXCLUDED_VMEMMAP 0x10 /* unused vmemmap pages are excluded */
> > +#define DUMP_DH_COMPRESSED_ZSTD 0x20 /* page is compressed with zstd */
> >
> > /* descriptor of each page for vmcore */
> > typedef struct page_desc {
> > diff --git a/help.c b/help.c
> > index 6c262a3ffcbb..f34838d59908 100644
> > --- a/help.c
> > +++ b/help.c
> > @@ -9420,8 +9420,8 @@ README_ENTER_DIRECTORY,
> > " Traditionally when vmcores are compressed via the makedumpfile(8) facility",
> > " the libz compression library is used, and by default the crash utility",
> > " only supports libz. Recently makedumpfile has been enhanced to optionally",
> > -" use either the LZO or snappy compression libraries. To build crash with",
> > -" either or both of those libraries, type \"make lzo\" or \"make snappy\".",
> > +" use the LZO, snappy or zstd compression libraries. To build crash with any",
> > +" or all of those libraries, type \"make lzo\", \"make snappy\" or \"make zstd\".",
> > "",
> > " crash supports valgrind Memcheck tool on the crash's custom memory allocator.",
> > " To build crash with this feature enabled, type \"make valgrind\" and then run",
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