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5222 l2arc compression buffers "leak"
Author: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Reviewed by: Xin Li <delphij@FreeBSD.org>
@@ -306,10 +306,11 @@
kstat_named_t arcstat_l2_writes_error;
kstat_named_t arcstat_l2_writes_hdr_miss;
kstat_named_t arcstat_l2_evict_lock_retry;
kstat_named_t arcstat_l2_evict_reading;
kstat_named_t arcstat_l2_free_on_write;
+ kstat_named_t arcstat_l2_cdata_free_on_write;
kstat_named_t arcstat_l2_abort_lowmem;
kstat_named_t arcstat_l2_cksum_bad;
kstat_named_t arcstat_l2_io_error;
kstat_named_t arcstat_l2_size;
kstat_named_t arcstat_l2_asize;
@@ -372,10 +373,11 @@
{ "l2_writes_error", KSTAT_DATA_UINT64 },
{ "l2_writes_hdr_miss", KSTAT_DATA_UINT64 },
{ "l2_evict_lock_retry", KSTAT_DATA_UINT64 },
{ "l2_evict_reading", KSTAT_DATA_UINT64 },
{ "l2_free_on_write", KSTAT_DATA_UINT64 },
+ { "l2_cdata_free_on_write", KSTAT_DATA_UINT64 },
{ "l2_abort_lowmem", KSTAT_DATA_UINT64 },
{ "l2_cksum_bad", KSTAT_DATA_UINT64 },
{ "l2_io_error", KSTAT_DATA_UINT64 },
{ "l2_size", KSTAT_DATA_UINT64 },
{ "l2_asize", KSTAT_DATA_UINT64 },
@@ -1471,28 +1473,36 @@
ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH),
demand, prefetch, hdr->b_type != ARC_BUFC_METADATA,
data, metadata, hits);
}
+static void
+arc_buf_free_on_write(void *data, size_t size,
+ void (*free_func)(void *, size_t))
+{
+ l2arc_data_free_t *df;
+
+ df = kmem_alloc(sizeof (l2arc_data_free_t), KM_SLEEP);
+ df->l2df_data = data;
+ df->l2df_size = size;
+ df->l2df_func = free_func;
+ mutex_enter(&l2arc_free_on_write_mtx);
+ list_insert_head(l2arc_free_on_write, df);
+ mutex_exit(&l2arc_free_on_write_mtx);
+}
+
/*
* Free the arc data buffer. If it is an l2arc write in progress,
* the buffer is placed on l2arc_free_on_write to be freed later.
*/
static void
arc_buf_data_free(arc_buf_t *buf, void (*free_func)(void *, size_t))
{
arc_buf_hdr_t *hdr = buf->b_hdr;
if (HDR_L2_WRITING(hdr)) {
- l2arc_data_free_t *df;
- df = kmem_alloc(sizeof (l2arc_data_free_t), KM_SLEEP);
- df->l2df_data = buf->b_data;
- df->l2df_size = hdr->b_size;
- df->l2df_func = free_func;
- mutex_enter(&l2arc_free_on_write_mtx);
- list_insert_head(l2arc_free_on_write, df);
- mutex_exit(&l2arc_free_on_write_mtx);
+ arc_buf_free_on_write(buf->b_data, hdr->b_size, free_func);
ARCSTAT_BUMP(arcstat_l2_free_on_write);
} else {
free_func(buf->b_data, hdr->b_size);
}
}
@@ -1500,10 +1510,27 @@
/*
* Free up buf->b_data and if 'remove' is set, then pull the
* arc_buf_t off of the the arc_buf_hdr_t's list and free it.
*/
static void
+arc_buf_l2_cdata_free(arc_buf_hdr_t *hdr)
+{
+ l2arc_buf_hdr_t *l2hdr = hdr->b_l2hdr;
+
+ ASSERT(MUTEX_HELD(&l2arc_buflist_mtx));
+
+ if (l2hdr->b_tmp_cdata == NULL)
+ return;
+
+ ASSERT(HDR_L2_WRITING(hdr));
+ arc_buf_free_on_write(l2hdr->b_tmp_cdata, hdr->b_size,
+ zio_data_buf_free);
+ ARCSTAT_BUMP(arcstat_l2_cdata_free_on_write);
+ l2hdr->b_tmp_cdata = NULL;
+}
+
+static void
arc_buf_destroy(arc_buf_t *buf, boolean_t recycle, boolean_t remove)
{
arc_buf_t **bufp;
/* free up data associated with the buf */
@@ -1594,10 +1621,11 @@
l2hdr = hdr->b_l2hdr;
}
if (l2hdr != NULL) {
list_remove(l2hdr->b_dev->l2ad_buflist, hdr);
+ arc_buf_l2_cdata_free(hdr);
ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize);
vdev_space_update(l2hdr->b_dev->l2ad_vdev,
-l2hdr->b_asize, 0, 0);
kmem_free(l2hdr, sizeof (l2arc_buf_hdr_t));
@@ -3349,10 +3377,11 @@
}
l2hdr = hdr->b_l2hdr;
if (l2hdr) {
mutex_enter(&l2arc_buflist_mtx);
+ arc_buf_l2_cdata_free(hdr);
hdr->b_l2hdr = NULL;
list_remove(l2hdr->b_dev->l2ad_buflist, hdr);
}
buf_size = hdr->b_size;
@@ -4529,10 +4558,15 @@
if (ab->b_l2hdr != NULL) {
abl2 = ab->b_l2hdr;
ARCSTAT_INCR(arcstat_l2_asize, -abl2->b_asize);
bytes_evicted += abl2->b_asize;
ab->b_l2hdr = NULL;
+ /*
+ * We are destroying l2hdr, so ensure that
+ * its compressed buffer, if any, is not leaked.
+ */
+ ASSERT(abl2->b_tmp_cdata == NULL);
kmem_free(abl2, sizeof (l2arc_buf_hdr_t));
ARCSTAT_INCR(arcstat_l2_size, -ab->b_size);
}
list_remove(buflist, ab);
@@ -4757,10 +4791,18 @@
* (and now potentially also compressed).
*/
buf_data = l2hdr->b_tmp_cdata;
buf_sz = l2hdr->b_asize;
+ /*
+ * If the data has not been compressed, then clear b_tmp_cdata
+ * to make sure that it points only to a temporary compression
+ * buffer.
+ */
+ if (!L2ARC_IS_VALID_COMPRESS(l2hdr->b_compress))
+ l2hdr->b_tmp_cdata = NULL;
+
/* Compression may have squashed the buffer to zero length. */
if (buf_sz != 0) {
uint64_t buf_p_sz;
wzio = zio_write_phys(pio, dev->l2ad_vdev,
@@ -4947,19 +4989,22 @@
static void
l2arc_release_cdata_buf(arc_buf_hdr_t *ab)
{
l2arc_buf_hdr_t *l2hdr = ab->b_l2hdr;
- if (l2hdr->b_compress == ZIO_COMPRESS_LZ4) {
+ ASSERT(L2ARC_IS_VALID_COMPRESS(l2hdr->b_compress));
+ if (l2hdr->b_compress != ZIO_COMPRESS_EMPTY) {
/*
* If the data was compressed, then we've allocated a
* temporary buffer for it, so now we need to release it.
*/
ASSERT(l2hdr->b_tmp_cdata != NULL);
zio_data_buf_free(l2hdr->b_tmp_cdata, ab->b_size);
- }
l2hdr->b_tmp_cdata = NULL;
+ } else {
+ ASSERT(l2hdr->b_tmp_cdata == NULL);
+ }
}
/*
* This thread feeds the L2ARC at regular intervals. This is the beating
* heart of the L2ARC.