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@xxxxxxxxxx>
On Fri, 17 Sep 2021 07:55:32 +0000
HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx> 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@xxxxxxxxxxxxx>
> 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@xxxxxxx>
> ---
> 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.
> {
> 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.
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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