From 5d232b56379e7d9a7ef1cb6048dd9ffea920a54f Mon Sep 17 00:00:00 2001 From: Chunwei Chen Date: Thu, 1 Feb 2018 16:19:36 -0800 Subject: [PATCH] Fix zdb -R decompression There are some issues in the zdb -R decompression implementation. The first is that ZLE can easily decompress non-ZLE streams. So we add ZDB_NO_ZLE env to make zdb skip ZLE. The second is the random bytes appended to pabd, pbuf2 stuff. This serve no purpose at all, those bytes shouldn't be read during decompression anyway. Instead, we randomize lbuf2, so that we can make sure decompression fill exactly to lsize by bcmp lbuf and lbuf2. The last one is the condition to detect fail is wrong. Reviewed-by: Brian Behlendorf Reviewed-by: loli10K Signed-off-by: Chunwei Chen Closes #7099 Closes #4984 --- cmd/zdb/zdb.c | 38 ++++++++++++++++++-------------------- man/man8/zdb.8 | 4 +++- 2 files changed, 21 insertions(+), 21 deletions(-) diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c index 0cc1656a8208..2d80589cafc0 100644 --- a/cmd/zdb/zdb.c +++ b/cmd/zdb/zdb.c @@ -3895,13 +3895,6 @@ zdb_vdev_lookup(vdev_t *vdev, char *path) return (NULL); } -/* ARGSUSED */ -static int -random_get_pseudo_bytes_cb(void *buf, size_t len, void *unused) -{ - return (random_get_pseudo_bytes(buf, len)); -} - /* * Read a block from a pool and print it out. The syntax of the * block descriptor is: @@ -4064,17 +4057,8 @@ zdb_read_block(char *thing, spa_t *spa) * every decompress function at every inflated blocksize. */ enum zio_compress c; - void *pbuf2 = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL); void *lbuf2 = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL); - abd_copy_to_buf(pbuf2, pabd, psize); - - VERIFY0(abd_iterate_func(pabd, psize, SPA_MAXBLOCKSIZE - psize, - random_get_pseudo_bytes_cb, NULL)); - - VERIFY0(random_get_pseudo_bytes((uint8_t *)pbuf2 + psize, - SPA_MAXBLOCKSIZE - psize)); - /* * XXX - On the one hand, with SPA_MAXBLOCKSIZE at 16MB, * this could take a while and we should let the user know @@ -4084,13 +4068,29 @@ zdb_read_block(char *thing, spa_t *spa) for (lsize = psize + SPA_MINBLOCKSIZE; lsize <= SPA_MAXBLOCKSIZE; lsize += SPA_MINBLOCKSIZE) { for (c = 0; c < ZIO_COMPRESS_FUNCTIONS; c++) { + /* + * ZLE can easily decompress non zle stream. + * So have an option to disable it. + */ + if (c == ZIO_COMPRESS_ZLE && + getenv("ZDB_NO_ZLE")) + continue; + (void) fprintf(stderr, "Trying %05llx -> %05llx (%s)\n", (u_longlong_t)psize, (u_longlong_t)lsize, zio_compress_table[c].ci_name); + + /* + * We randomize lbuf2, and decompress to both + * lbuf and lbuf2. This way, we will know if + * decompression fill exactly to lsize. + */ + VERIFY0(random_get_pseudo_bytes(lbuf2, lsize)); + if (zio_decompress_data(c, pabd, lbuf, psize, lsize) == 0 && - zio_decompress_data_buf(c, pbuf2, + zio_decompress_data(c, pabd, lbuf2, psize, lsize) == 0 && bcmp(lbuf, lbuf2, lsize) == 0) break; @@ -4098,11 +4098,9 @@ zdb_read_block(char *thing, spa_t *spa) if (c != ZIO_COMPRESS_FUNCTIONS) break; } - - umem_free(pbuf2, SPA_MAXBLOCKSIZE); umem_free(lbuf2, SPA_MAXBLOCKSIZE); - if (lsize <= psize) { + if (lsize > SPA_MAXBLOCKSIZE) { (void) printf("Decompress of %s failed\n", thing); goto out; } diff --git a/man/man8/zdb.8 b/man/man8/zdb.8 index 4e47de7bef8d..d991aae4caac 100644 --- a/man/man8/zdb.8 +++ b/man/man8/zdb.8 @@ -246,7 +246,9 @@ and, optionally, .It Sy b Ar offset Print block pointer .It Sy d -Decompress the block +Decompress the block. Set environment variable +.Nm ZBD_NO_ZLE +to skip zle when guessing. .It Sy e Byte swap the block .It Sy g