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Illumos 5701 - zpool list reports incorrect "alloc" value for cache devices
5701 zpool list reports incorrect "alloc" value for cache devices Reviewed by: Matthew Ahrens <mahrens@delphix.com> Reviewed by: George Wilson <george@delphix.com> Reviewed by: Alek Pinchuk <alek.pinchuk@nexenta.com> Approved by: Dan McDonald <danmcd@omniti.com> References: https://www.illumos.org/issues/5701 https://github.com/illumos/illumos-gate/commit/a52fc31 Porting Notes: arc_space_return(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS); correctly placed at arc_hdr_l2hdr_destroy(arc_buf_hdr_t *hdr). Ported by: kernelOfTruth kerneloftruth@gmail.com Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Prakash Surya
Brian Behlendorf
parent
fa720217b9
commit
d962d5dad9
@ -172,12 +172,12 @@ typedef struct l2arc_dev {
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uint64_t l2ad_hand; /* next write location */
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uint64_t l2ad_start; /* first addr on device */
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uint64_t l2ad_end; /* last addr on device */
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uint64_t l2ad_evict; /* last addr eviction reached */
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boolean_t l2ad_first; /* first sweep through */
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boolean_t l2ad_writing; /* currently writing */
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kmutex_t l2ad_mtx; /* lock for buffer list */
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list_t l2ad_buflist; /* buffer list */
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list_node_t l2ad_node; /* device list node */
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refcount_t l2ad_alloc; /* allocated bytes */
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} l2arc_dev_t;
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typedef struct l2arc_buf_hdr {
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187
module/zfs/arc.c
187
module/zfs/arc.c
@ -627,6 +627,16 @@ uint64_t zfs_crc64_table[256];
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#define L2ARC_FEED_SECS 1 /* caching interval secs */
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#define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */
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/*
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* Used to distinguish headers that are being process by
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* l2arc_write_buffers(), but have yet to be assigned to a l2arc disk
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* address. This can happen when the header is added to the l2arc's list
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* of buffers to write in the first stage of l2arc_write_buffers(), but
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* has not yet been written out which happens in the second stage of
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* l2arc_write_buffers().
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*/
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#define L2ARC_ADDR_UNSET ((uint64_t)(-1))
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#define l2arc_writes_sent ARCSTAT(arcstat_l2_writes_sent)
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#define l2arc_writes_done ARCSTAT(arcstat_l2_writes_done)
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@ -1014,6 +1024,7 @@ arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new)
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buf_hash_remove(hdr);
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bcopy(hdr, nhdr, HDR_L2ONLY_SIZE);
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if (new == hdr_full_cache) {
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nhdr->b_flags |= ARC_FLAG_HAS_L1HDR;
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/*
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@ -1070,6 +1081,20 @@ arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new)
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mutex_exit(&dev->l2ad_mtx);
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/*
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* Since we're using the pointer address as the tag when
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* incrementing and decrementing the l2ad_alloc refcount, we
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* must remove the old pointer (that we're about to destroy) and
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* add the new pointer to the refcount. Otherwise we'd remove
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* the wrong pointer address when calling arc_hdr_destroy() later.
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*/
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(void) refcount_remove_many(&dev->l2ad_alloc,
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hdr->b_l2hdr.b_asize, hdr);
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(void) refcount_add_many(&dev->l2ad_alloc,
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nhdr->b_l2hdr.b_asize, nhdr);
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buf_discard_identity(hdr);
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hdr->b_freeze_cksum = NULL;
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kmem_cache_free(old, hdr);
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@ -1836,6 +1861,59 @@ arc_buf_destroy(arc_buf_t *buf, boolean_t remove)
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kmem_cache_free(buf_cache, buf);
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}
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static void
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arc_hdr_l2hdr_destroy(arc_buf_hdr_t *hdr)
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{
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l2arc_buf_hdr_t *l2hdr = &hdr->b_l2hdr;
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l2arc_dev_t *dev = l2hdr->b_dev;
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ASSERT(MUTEX_HELD(&dev->l2ad_mtx));
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ASSERT(HDR_HAS_L2HDR(hdr));
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list_remove(&dev->l2ad_buflist, hdr);
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arc_space_return(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS);
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/*
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* We don't want to leak the b_tmp_cdata buffer that was
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* allocated in l2arc_write_buffers()
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*/
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arc_buf_l2_cdata_free(hdr);
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/*
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* If the l2hdr's b_daddr is equal to L2ARC_ADDR_UNSET, then
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* this header is being processed by l2arc_write_buffers() (i.e.
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* it's in the first stage of l2arc_write_buffers()).
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* Re-affirming that truth here, just to serve as a reminder. If
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* b_daddr does not equal L2ARC_ADDR_UNSET, then the header may or
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* may not have its HDR_L2_WRITING flag set. (the write may have
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* completed, in which case HDR_L2_WRITING will be false and the
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* b_daddr field will point to the address of the buffer on disk).
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*/
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IMPLY(l2hdr->b_daddr == L2ARC_ADDR_UNSET, HDR_L2_WRITING(hdr));
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/*
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* If b_daddr is equal to L2ARC_ADDR_UNSET, we're racing with
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* l2arc_write_buffers(). Since we've just removed this header
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* from the l2arc buffer list, this header will never reach the
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* second stage of l2arc_write_buffers(), which increments the
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* accounting stats for this header. Thus, we must be careful
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* not to decrement them for this header either.
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*/
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if (l2hdr->b_daddr != L2ARC_ADDR_UNSET) {
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ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize);
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ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
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vdev_space_update(dev->l2ad_vdev,
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-l2hdr->b_asize, 0, 0);
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(void) refcount_remove_many(&dev->l2ad_alloc,
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l2hdr->b_asize, hdr);
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}
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hdr->b_flags &= ~ARC_FLAG_HAS_L2HDR;
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}
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static void
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arc_hdr_destroy(arc_buf_hdr_t *hdr)
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{
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@ -1849,30 +1927,26 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr)
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ASSERT(!HDR_IN_HASH_TABLE(hdr));
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if (HDR_HAS_L2HDR(hdr)) {
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l2arc_buf_hdr_t *l2hdr = &hdr->b_l2hdr;
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boolean_t buflist_held = MUTEX_HELD(&l2hdr->b_dev->l2ad_mtx);
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if (!buflist_held) {
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mutex_enter(&l2hdr->b_dev->l2ad_mtx);
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l2hdr = &hdr->b_l2hdr;
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}
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list_remove(&l2hdr->b_dev->l2ad_buflist, hdr);
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/*
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* We don't want to leak the b_tmp_cdata buffer that was
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* allocated in l2arc_write_buffers()
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*/
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arc_buf_l2_cdata_free(hdr);
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arc_space_return(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS);
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ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
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ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize);
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l2arc_dev_t *dev = hdr->b_l2hdr.b_dev;
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boolean_t buflist_held = MUTEX_HELD(&dev->l2ad_mtx);
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if (!buflist_held)
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mutex_exit(&l2hdr->b_dev->l2ad_mtx);
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mutex_enter(&dev->l2ad_mtx);
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hdr->b_flags &= ~ARC_FLAG_HAS_L2HDR;
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/*
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* Even though we checked this conditional above, we
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* need to check this again now that we have the
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* l2ad_mtx. This is because we could be racing with
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* another thread calling l2arc_evict() which might have
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* destroyed this header's L2 portion as we were waiting
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* to acquire the l2ad_mtx. If that happens, we don't
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* want to re-destroy the header's L2 portion.
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*/
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if (HDR_HAS_L2HDR(hdr))
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arc_hdr_l2hdr_destroy(hdr);
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if (!buflist_held)
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mutex_exit(&dev->l2ad_mtx);
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}
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if (!BUF_EMPTY(hdr))
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@ -4343,21 +4417,20 @@ arc_release(arc_buf_t *buf, void *tag)
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ASSERT(refcount_count(&hdr->b_l1hdr.b_refcnt) > 0);
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if (HDR_HAS_L2HDR(hdr)) {
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ARCSTAT_INCR(arcstat_l2_asize, -hdr->b_l2hdr.b_asize);
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ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
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mutex_enter(&hdr->b_l2hdr.b_dev->l2ad_mtx);
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list_remove(&hdr->b_l2hdr.b_dev->l2ad_buflist, hdr);
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/*
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* We don't want to leak the b_tmp_cdata buffer that was
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* allocated in l2arc_write_buffers()
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* We have to recheck this conditional again now that
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* we're holding the l2ad_mtx to prevent a race with
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* another thread which might be concurrently calling
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* l2arc_evict(). In that case, l2arc_evict() might have
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* destroyed the header's L2 portion as we were waiting
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* to acquire the l2ad_mtx.
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*/
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arc_buf_l2_cdata_free(hdr);
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if (HDR_HAS_L2HDR(hdr))
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arc_hdr_l2hdr_destroy(hdr);
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mutex_exit(&hdr->b_l2hdr.b_dev->l2ad_mtx);
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hdr->b_flags &= ~ARC_FLAG_HAS_L2HDR;
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}
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/*
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@ -5437,6 +5510,10 @@ top:
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ARCSTAT_INCR(arcstat_l2_asize, -hdr->b_l2hdr.b_asize);
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ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
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bytes_dropped += hdr->b_l2hdr.b_asize;
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(void) refcount_remove_many(&dev->l2ad_alloc,
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hdr->b_l2hdr.b_asize, hdr);
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}
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/*
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@ -5595,7 +5672,6 @@ l2arc_evict(l2arc_dev_t *dev, uint64_t distance, boolean_t all)
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arc_buf_hdr_t *hdr, *hdr_prev;
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kmutex_t *hash_lock;
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uint64_t taddr;
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int64_t bytes_evicted = 0;
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buflist = &dev->l2ad_buflist;
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@ -5686,25 +5762,15 @@ top:
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hdr->b_flags |= ARC_FLAG_L2_EVICTED;
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}
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/*
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* Tell ARC this no longer exists in L2ARC.
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*/
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/* Tell ARC this no longer exists in L2ARC. */
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ARCSTAT_INCR(arcstat_l2_asize, -hdr->b_l2hdr.b_asize);
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ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
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hdr->b_flags &= ~ARC_FLAG_HAS_L2HDR;
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list_remove(buflist, hdr);
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/* Ensure this header has finished being written */
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ASSERT(!HDR_L2_WRITING(hdr));
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ASSERT3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL);
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arc_hdr_l2hdr_destroy(hdr);
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}
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mutex_exit(hash_lock);
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}
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mutex_exit(&dev->l2ad_mtx);
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vdev_space_update(dev->l2ad_vdev, -bytes_evicted, 0, 0);
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dev->l2ad_evict = taddr;
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}
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/*
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@ -5847,6 +5913,29 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz,
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hdr->b_l2hdr.b_hits = 0;
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hdr->b_l1hdr.b_tmp_cdata = hdr->b_l1hdr.b_buf->b_data;
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/*
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* Explicitly set the b_daddr field to a known
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* value which means "invalid address". This
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* enables us to differentiate which stage of
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* l2arc_write_buffers() the particular header
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* is in (e.g. this loop, or the one below).
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* ARC_FLAG_L2_WRITING is not enough to make
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* this distinction, and we need to know in
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* order to do proper l2arc vdev accounting in
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* arc_release() and arc_hdr_destroy().
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*
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* Note, we can't use a new flag to distinguish
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* the two stages because we don't hold the
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* header's hash_lock below, in the second stage
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* of this function. Thus, we can't simply
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* change the b_flags field to denote that the
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* IO has been sent. We can change the b_daddr
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* field of the L2 portion, though, since we'll
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* be holding the l2ad_mtx; which is why we're
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* using it to denote the header's state change.
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*/
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hdr->b_l2hdr.b_daddr = L2ARC_ADDR_UNSET;
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buf_sz = hdr->b_size;
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hdr->b_flags |= ARC_FLAG_HAS_L2HDR;
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@ -5926,6 +6015,13 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz,
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buf_data = hdr->b_l1hdr.b_tmp_cdata;
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buf_sz = hdr->b_l2hdr.b_asize;
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/*
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* We need to do this regardless if buf_sz is zero or
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* not, otherwise, when this l2hdr is evicted we'll
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* remove a reference that was never added.
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*/
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(void) refcount_add_many(&dev->l2ad_alloc, buf_sz, hdr);
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/* Compression may have squashed the buffer to zero length. */
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if (buf_sz != 0) {
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uint64_t buf_p_sz;
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@ -5940,6 +6036,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz,
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(void) zio_nowait(wzio);
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write_asize += buf_sz;
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/*
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* Keep the clock hand suitably device-aligned.
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*/
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@ -5964,7 +6061,6 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz,
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*/
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if (dev->l2ad_hand >= (dev->l2ad_end - target_sz)) {
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dev->l2ad_hand = dev->l2ad_start;
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dev->l2ad_evict = dev->l2ad_start;
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dev->l2ad_first = B_FALSE;
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}
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@ -6290,7 +6386,6 @@ l2arc_add_vdev(spa_t *spa, vdev_t *vd)
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adddev->l2ad_start = VDEV_LABEL_START_SIZE;
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adddev->l2ad_end = VDEV_LABEL_START_SIZE + vdev_get_min_asize(vd);
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adddev->l2ad_hand = adddev->l2ad_start;
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adddev->l2ad_evict = adddev->l2ad_start;
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adddev->l2ad_first = B_TRUE;
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adddev->l2ad_writing = B_FALSE;
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list_link_init(&adddev->l2ad_node);
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@ -6304,6 +6399,7 @@ l2arc_add_vdev(spa_t *spa, vdev_t *vd)
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offsetof(arc_buf_hdr_t, b_l2hdr.b_l2node));
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vdev_space_update(vd, 0, 0, adddev->l2ad_end - adddev->l2ad_hand);
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refcount_create(&adddev->l2ad_alloc);
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/*
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* Add device to global list
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@ -6349,6 +6445,7 @@ l2arc_remove_vdev(vdev_t *vd)
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l2arc_evict(remdev, 0, B_TRUE);
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list_destroy(&remdev->l2ad_buflist);
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mutex_destroy(&remdev->l2ad_mtx);
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refcount_destroy(&remdev->l2ad_alloc);
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kmem_free(remdev, sizeof (l2arc_dev_t));
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}
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