Looks like this could have introduced random data corruption, have you
seen this in practice?
On 17/11/2014 14:45, Andriy Gapon wrote:
Author: avg
Date: Mon Nov 17 14:45:42 2014
New Revision: 274628
URL: https://svnweb.freebsd.org/changeset/base/274628
Log:
l2arc: restore correct rounding up of asize of compressed data
This rounding up was lost in a mismerge of illumos code.
See r268075 MFV r267565.
After that commit zio_compress_data() no longer performs any compressed
size adjustment, so it needs to be done externally. On FreeBSD we round
up the size using vdev_ashift rather than SPA_MINBLOCKSIZE so that 4KB
devices are properly supported.
Additionally, zero out the buffer tail only if compression succeeds.
The compression is considered successful if the size of compressed
data after rounding up to account for the vdev ashift is less than the
original data size. It does not make sense to have the data compressed
if all the savings are lost to rounding up.
With the new zio_compress_data() it could have been possible that the
rounded compressed size would be greater than the original size and thus
we could zero beyond the allocated buffer if the zeroing code was kept
at the original place.
Discussed with: delphij, gibbs
MFC after: 2 weeks
X-MFC with: r274627
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Mon Nov 17
14:16:02 2014 (r274627)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Mon Nov 17
14:45:42 2014 (r274628)
@@ -5326,12 +5326,6 @@ l2arc_compress_buf(l2arc_buf_hdr_t *l2hd
csize = zio_compress_data(ZIO_COMPRESS_LZ4, l2hdr->b_tmp_cdata,
cdata, l2hdr->b_asize);
- rounded = P2ROUNDUP(csize, (size_t)SPA_MINBLOCKSIZE);
- if (rounded > csize) {
- bzero((char *)cdata + csize, rounded - csize);
- csize = rounded;
- }
-
if (csize == 0) {
/* zero block, indicate that there's nothing to write */
zio_data_buf_free(cdata, len);
@@ -5340,11 +5334,19 @@ l2arc_compress_buf(l2arc_buf_hdr_t *l2hd
l2hdr->b_tmp_cdata = NULL;
ARCSTAT_BUMP(arcstat_l2_compress_zeros);
return (B_TRUE);
- } else if (csize > 0 && csize < len) {
+ }
+
+ rounded = P2ROUNDUP(csize,
+ (size_t)1 << l2hdr->b_dev->l2ad_vdev->vdev_ashift);
+ if (rounded < len) {
/*
* Compression succeeded, we'll keep the cdata around for
* writing and release it afterwards.
*/
+ if (rounded > csize) {
+ bzero((char *)cdata + csize, rounded - csize);
+ csize = rounded;
+ }
l2hdr->b_compress = ZIO_COMPRESS_LZ4;
l2hdr->b_asize = csize;
l2hdr->b_tmp_cdata = cdata;
_______________________________________________
svn-src-head@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
