I filed https://www.illumos.org/issues/11051 with a summary of what I've
discovered.
On 05/19/19 13:09, Igor Kozhukhov wrote:
add openzfs dev list where it can be interested to ZoL and others too.
i think it is additional issue what was fixed by Tom Caputi with scrub.
-Igor
On May 19, 2019, at 9:53 PM, Bill Sommerfeld <[email protected]> wrote:
On 05/18/19 14:27, Jerry Jelinek wrote:
I’ll see if I can reproduce this and I’ll also spend some time looking at the
code to see if I can spot anything.
I've figured out how to reproduce it. It doesn't appear to happen with
compress=lz4 for reasons I haven't yet figured out but it's easy to reproduce
by creating a bunch of very short random files in a filesystem using either
compress=zle or compress=lzjb. (I haven't tried others).
0) use a pool with embedded_data enabled.
1) use a compression algorithm other than lz4:
zfs set compress=lzjb path/to/filesys
2) create a bunch of small files with random content:
cd /path/to/filesys
for f in $(seq 1024)
do
dd if=/dev/urandom of=$f bs=16 count=1
done
3) scrub, watch "issued" value go nuts when the scan reaches the embedded bp's
containing the above files.
I'm convinced it's the BP_IS_EMBEDDED() thing and it appears it can be fixed by:
diff --git a/usr/src/uts/common/fs/zfs/dsl_scan.c
b/usr/src/uts/common/fs/zfs/dsl_scan.c
index ca82195178..b15b0931ed 100644
--- a/usr/src/uts/common/fs/zfs/dsl_scan.c
+++ b/usr/src/uts/common/fs/zfs/dsl_scan.c
@@ -3431,6 +3431,9 @@ count_block(dsl_scan_t *scn, zfs_all_blkstats_t *zab,
const blkptr_t *bp)
{
int i;
+ if (BP_IS_EMBEDDED(bp))
+ return;
+
/*
* Update the spa's stats on how many bytes we have issued.
* Sequential scrubs create a zio for each DVA of the bp. Each
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