Date: Wed, 14 Oct 2015 07:28:36 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-vendor@freebsd.org Subject: svn commit: r289294 - vendor-sys/illumos/dist/uts/common/fs/zfs Message-ID: <201510140728.t9E7SaTF053107@repo.freebsd.org>
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Author: mav Date: Wed Oct 14 07:28:36 2015 New Revision: 289294 URL: https://svnweb.freebsd.org/changeset/base/289294 Log: 5219 l2arc_write_buffers() may write beyond target_sz Reviewed by: Matthew Ahrens <mahrens@delphix.com> Reviewed by: Saso Kiselkov <skiselkov@gmail.com> Reviewed by: George Wilson <george@delphix.com> Reviewed by: Steven Hartland <steven.hartland@multiplay.co.uk> Reviewed by: Justin Gibbs <gibbs@FreeBSD.org> Approved by: Matthew Ahrens <mahrens@delphix.com> Author: Andriy Gapon <avg@freebsd.org> illumos/illumos-gate@d7d9a6d919f92d74ea0510a53f8441396048e800 Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c ============================================================================== --- vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c Wed Oct 14 06:57:28 2015 (r289293) +++ vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c Wed Oct 14 07:28:36 2015 (r289294) @@ -5902,7 +5902,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_de boolean_t *headroom_boost) { arc_buf_hdr_t *hdr, *hdr_prev, *head; - uint64_t write_asize, write_psize, write_sz, headroom, + uint64_t write_asize, write_sz, headroom, buf_compress_minsz; void *buf_data; boolean_t full; @@ -5917,7 +5917,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_de *headroom_boost = B_FALSE; pio = NULL; - write_sz = write_asize = write_psize = 0; + write_sz = write_asize = 0; full = B_FALSE; head = kmem_cache_alloc(hdr_l2only_cache, KM_PUSHPAGE); head->b_flags |= ARC_FLAG_L2_WRITE_HEAD; @@ -5954,6 +5954,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_de for (; hdr; hdr = hdr_prev) { kmutex_t *hash_lock; uint64_t buf_sz; + uint64_t buf_a_sz; if (arc_warm == B_FALSE) hdr_prev = multilist_sublist_next(mls, hdr); @@ -5982,7 +5983,15 @@ l2arc_write_buffers(spa_t *spa, l2arc_de continue; } - if ((write_sz + hdr->b_size) > target_sz) { + /* + * Assume that the buffer is not going to be compressed + * and could take more space on disk because of a larger + * disk block size. + */ + buf_sz = hdr->b_size; + buf_a_sz = vdev_psize_to_asize(dev->l2ad_vdev, buf_sz); + + if ((write_asize + buf_a_sz) > target_sz) { full = B_TRUE; mutex_exit(hash_lock); break; @@ -6046,7 +6055,6 @@ l2arc_write_buffers(spa_t *spa, l2arc_de */ hdr->b_l2hdr.b_daddr = L2ARC_ADDR_UNSET; - buf_sz = hdr->b_size; hdr->b_flags |= ARC_FLAG_HAS_L2HDR; mutex_enter(&dev->l2ad_mtx); @@ -6063,6 +6071,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_de mutex_exit(hash_lock); write_sz += buf_sz; + write_asize += buf_a_sz; } multilist_sublist_unlock(mls); @@ -6082,6 +6091,19 @@ l2arc_write_buffers(spa_t *spa, l2arc_de mutex_enter(&dev->l2ad_mtx); /* + * Note that elsewhere in this file arcstat_l2_asize + * and the used space on l2ad_vdev are updated using b_asize, + * which is not necessarily rounded up to the device block size. + * Too keep accounting consistent we do the same here as well: + * stats_size accumulates the sum of b_asize of the written buffers, + * while write_asize accumulates the sum of b_asize rounded up + * to the device block size. + * The latter sum is used only to validate the corectness of the code. + */ + uint64_t stats_size = 0; + write_asize = 0; + + /* * Now start writing the buffers. We're starting at the write head * and work backwards, retracing the course of the buffer selector * loop above. @@ -6134,7 +6156,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_de /* Compression may have squashed the buffer to zero length. */ if (buf_sz != 0) { - uint64_t buf_p_sz; + uint64_t buf_a_sz; wzio = zio_write_phys(pio, dev->l2ad_vdev, dev->l2ad_hand, buf_sz, buf_data, ZIO_CHECKSUM_OFF, @@ -6145,14 +6167,14 @@ l2arc_write_buffers(spa_t *spa, l2arc_de zio_t *, wzio); (void) zio_nowait(wzio); - write_asize += buf_sz; + stats_size += buf_sz; /* * Keep the clock hand suitably device-aligned. */ - buf_p_sz = vdev_psize_to_asize(dev->l2ad_vdev, buf_sz); - write_psize += buf_p_sz; - dev->l2ad_hand += buf_p_sz; + buf_a_sz = vdev_psize_to_asize(dev->l2ad_vdev, buf_sz); + write_asize += buf_a_sz; + dev->l2ad_hand += buf_a_sz; } } @@ -6162,8 +6184,8 @@ l2arc_write_buffers(spa_t *spa, l2arc_de ARCSTAT_BUMP(arcstat_l2_writes_sent); ARCSTAT_INCR(arcstat_l2_write_bytes, write_asize); ARCSTAT_INCR(arcstat_l2_size, write_sz); - ARCSTAT_INCR(arcstat_l2_asize, write_asize); - vdev_space_update(dev->l2ad_vdev, write_asize, 0, 0); + ARCSTAT_INCR(arcstat_l2_asize, stats_size); + vdev_space_update(dev->l2ad_vdev, stats_size, 0, 0); /* * Bump device hand to the device start if it is approaching the end.
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