From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41801) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dG0AR-0002dL-2D for qemu-devel@nongnu.org; Wed, 31 May 2017 05:43:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dG0AN-0001qh-DK for qemu-devel@nongnu.org; Wed, 31 May 2017 05:43:51 -0400 Sender: Paolo Bonzini From: Paolo Bonzini Date: Wed, 31 May 2017 11:43:28 +0200 Message-Id: <20170531094330.1808-10-pbonzini@redhat.com> In-Reply-To: <20170531094330.1808-1-pbonzini@redhat.com> References: <20170531094330.1808-1-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 09/11] qed: protect table cache with CoMutex List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, qemu-block@nongnu.org, mreitz@redhat.com This makes the driver thread-safe. The CoMutex is dropped temporarily while accessing the data clusters or the backing file. Signed-off-by: Paolo Bonzini --- block/qed-cluster.c | 4 +- block/qed-l2-cache.c | 6 +++ block/qed-table.c | 24 +++++++--- block/qed.c | 131 ++++++++++++++++++++++++++++++++++----------------- block/qed.h | 11 +++-- 5 files changed, 121 insertions(+), 55 deletions(-) diff --git a/block/qed-cluster.c b/block/qed-cluster.c index 88dc979d8c..fd8722e08f 100644 --- a/block/qed-cluster.c +++ b/block/qed-cluster.c @@ -85,6 +85,8 @@ static unsigned int qed_count_contiguous_clusters(BDRVQEDState *s, * * On failure QED_CLUSTER_L2 or QED_CLUSTER_L1 is returned for missing L2 or L1 * table offset, respectively. len is number of contiguous unallocated bytes. + * + * Called with table_lock held. */ int qed_find_cluster(BDRVQEDState *s, QEDRequest *request, uint64_t pos, size_t *len, uint64_t *img_offset) @@ -111,7 +113,6 @@ int qed_find_cluster(BDRVQEDState *s, QEDRequest *request, uint64_t pos, } ret = qed_read_l2_table(s, request, l2_offset); - qed_acquire(s); if (ret) { goto out; } @@ -136,6 +137,5 @@ int qed_find_cluster(BDRVQEDState *s, QEDRequest *request, uint64_t pos, out: *img_offset = offset; - qed_release(s); return ret; } diff --git a/block/qed-l2-cache.c b/block/qed-l2-cache.c index 5cba794650..b548362398 100644 --- a/block/qed-l2-cache.c +++ b/block/qed-l2-cache.c @@ -101,6 +101,8 @@ CachedL2Table *qed_alloc_l2_cache_entry(L2TableCache *l2_cache) /** * Decrease an entry's reference count and free if necessary when the reference * count drops to zero. + * + * Called with table_lock held. */ void qed_unref_l2_cache_entry(CachedL2Table *entry) { @@ -122,6 +124,8 @@ void qed_unref_l2_cache_entry(CachedL2Table *entry) * * For a cached entry, this function increases the reference count and returns * the entry. + * + * Called with table_lock held. */ CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset) { @@ -150,6 +154,8 @@ CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset) * N.B. This function steals a reference to the l2_table from the caller so the * caller must obtain a new reference by issuing a call to * qed_find_l2_cache_entry(). + * + * Called with table_lock held. */ void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table) { diff --git a/block/qed-table.c b/block/qed-table.c index ebee2c50f0..eead8b0fc7 100644 --- a/block/qed-table.c +++ b/block/qed-table.c @@ -18,6 +18,7 @@ #include "qed.h" #include "qemu/bswap.h" +/* Called either from qed_check or with table_lock held. */ static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table) { QEMUIOVector qiov; @@ -32,18 +33,22 @@ static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table) trace_qed_read_table(s, offset, table); + if (qemu_in_coroutine()) { + qemu_co_mutex_unlock(&s->table_lock); + } ret = bdrv_preadv(s->bs->file, offset, &qiov); + if (qemu_in_coroutine()) { + qemu_co_mutex_lock(&s->table_lock); + } if (ret < 0) { goto out; } /* Byteswap offsets */ - qed_acquire(s); noffsets = qiov.size / sizeof(uint64_t); for (i = 0; i < noffsets; i++) { table->offsets[i] = le64_to_cpu(table->offsets[i]); } - qed_release(s); ret = 0; out: @@ -61,6 +66,8 @@ out: * @index: Index of first element * @n: Number of elements * @flush: Whether or not to sync to disk + * + * Called either from qed_check or with table_lock held. */ static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table, unsigned int index, unsigned int n, bool flush) @@ -97,16 +104,20 @@ static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table, /* Adjust for offset into table */ offset += start * sizeof(uint64_t); + if (qemu_in_coroutine()) { + qemu_co_mutex_unlock(&s->table_lock); + } ret = bdrv_pwritev(s->bs->file, offset, &qiov); + if (qemu_in_coroutine()) { + qemu_co_mutex_lock(&s->table_lock); + } trace_qed_write_table_cb(s, table, flush, ret); if (ret < 0) { goto out; } if (flush) { - qed_acquire(s); ret = bdrv_flush(s->bs); - qed_release(s); if (ret < 0) { goto out; } @@ -123,6 +134,7 @@ int qed_read_l1_table_sync(BDRVQEDState *s) return qed_read_table(s, s->header.l1_table_offset, s->l1_table); } +/* Called either from qed_check or with table_lock held. */ int qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n) { BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE); @@ -136,6 +148,7 @@ int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index, return qed_write_l1_table(s, index, n); } +/* Called either from qed_check or with table_lock held. */ int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset) { int ret; @@ -154,7 +167,6 @@ int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset) BLKDBG_EVENT(s->bs->file, BLKDBG_L2_LOAD); ret = qed_read_table(s, offset, request->l2_table->table); - qed_acquire(s); if (ret) { /* can't trust loaded L2 table anymore */ qed_unref_l2_cache_entry(request->l2_table); @@ -170,7 +182,6 @@ int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset) request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset); assert(request->l2_table != NULL); } - qed_release(s); return ret; } @@ -180,6 +191,7 @@ int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request, uint64_t offset return qed_read_l2_table(s, request, offset); } +/* Called either from qed_check or with table_lock held. */ int qed_write_l2_table(BDRVQEDState *s, QEDRequest *request, unsigned int index, unsigned int n, bool flush) { diff --git a/block/qed.c b/block/qed.c index 990210cd9c..3e93ef7873 100644 --- a/block/qed.c +++ b/block/qed.c @@ -94,6 +94,8 @@ int qed_write_header_sync(BDRVQEDState *s) * * This function only updates known header fields in-place and does not affect * extra data after the QED header. + * + * No new allocating reqs can start while this function runs. */ static int qed_write_header(BDRVQEDState *s) { @@ -110,6 +112,8 @@ static int qed_write_header(BDRVQEDState *s) QEMUIOVector qiov; int ret; + assert(s->allocating_acb || s->allocating_write_reqs_plugged); + buf = qemu_blockalign(s->bs, len); iov = (struct iovec) { .iov_base = buf, @@ -220,6 +224,8 @@ static int qed_read_string(BdrvChild *file, uint64_t offset, size_t n, * This function only produces the offset where the new clusters should be * written. It updates BDRVQEDState but does not make any changes to the image * file. + * + * Called with table_lock held. */ static uint64_t qed_alloc_clusters(BDRVQEDState *s, unsigned int n) { @@ -237,6 +243,8 @@ QEDTable *qed_alloc_table(BDRVQEDState *s) /** * Allocate a new zeroed L2 table + * + * Called with table_lock held. */ static CachedL2Table *qed_new_l2_table(BDRVQEDState *s) { @@ -250,19 +258,32 @@ static CachedL2Table *qed_new_l2_table(BDRVQEDState *s) return l2_table; } -static void qed_plug_allocating_write_reqs(BDRVQEDState *s) +static bool qed_plug_allocating_write_reqs(BDRVQEDState *s) { + qemu_co_mutex_lock(&s->table_lock); + + /* No reentrancy is allowed. */ assert(!s->allocating_write_reqs_plugged); + if (s->allocating_acb != NULL) { + /* Another allocating write came concurrently. This cannot happen + * from bdrv_qed_co_drain, but it can happen when the timer runs. + */ + qemu_co_mutex_unlock(&s->table_lock); + return false; + } s->allocating_write_reqs_plugged = true; + qemu_co_mutex_unlock(&s->table_lock); + return true; } static void qed_unplug_allocating_write_reqs(BDRVQEDState *s) { + qemu_co_mutex_lock(&s->table_lock); assert(s->allocating_write_reqs_plugged); - s->allocating_write_reqs_plugged = false; - qemu_co_enter_next(&s->allocating_write_reqs); + qemu_co_queue_next(&s->allocating_write_reqs); + qemu_co_mutex_unlock(&s->table_lock); } static void qed_need_check_timer_entry(void *opaque) @@ -270,17 +291,14 @@ static void qed_need_check_timer_entry(void *opaque) BDRVQEDState *s = opaque; int ret; - /* The timer should only fire when allocating writes have drained */ - assert(!s->allocating_acb); - trace_qed_need_check_timer_cb(s); - qed_acquire(s); - qed_plug_allocating_write_reqs(s); + if (!qed_plug_allocating_write_reqs(s)) { + return; + } /* Ensure writes are on disk before clearing flag */ ret = bdrv_co_flush(s->bs->file->bs); - qed_release(s); if (ret < 0) { goto out; } @@ -302,16 +320,6 @@ static void qed_need_check_timer_cb(void *opaque) qemu_coroutine_enter(co); } -void qed_acquire(BDRVQEDState *s) -{ - aio_context_acquire(bdrv_get_aio_context(s->bs)); -} - -void qed_release(BDRVQEDState *s) -{ - aio_context_release(bdrv_get_aio_context(s->bs)); -} - static void qed_start_need_check_timer(BDRVQEDState *s) { trace_qed_start_need_check_timer(s); @@ -373,6 +381,7 @@ static int bdrv_qed_do_open(BlockDriverState *bs, QDict *options, int flags, int ret; s->bs = bs; + qemu_co_mutex_init(&s->table_lock); qemu_co_queue_init(&s->allocating_write_reqs); ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header)); @@ -682,6 +691,7 @@ typedef struct { BlockDriverState **file; } QEDIsAllocatedCB; +/* Called with table_lock held. */ static void qed_is_allocated_cb(void *opaque, int ret, uint64_t offset, size_t len) { QEDIsAllocatedCB *cb = opaque; @@ -729,6 +739,7 @@ static int64_t coroutine_fn bdrv_qed_co_get_block_status(BlockDriverState *bs, uint64_t offset; int ret; + qemu_co_mutex_lock(&s->table_lock); ret = qed_find_cluster(s, &request, cb.pos, &len, &offset); qed_is_allocated_cb(&cb, ret, offset, len); @@ -736,6 +747,7 @@ static int64_t coroutine_fn bdrv_qed_co_get_block_status(BlockDriverState *bs, assert(cb.status != BDRV_BLOCK_OFFSET_MASK); qed_unref_l2_cache_entry(request.l2_table); + qemu_co_mutex_unlock(&s->table_lock); return cb.status; } @@ -865,6 +877,8 @@ out: * * The cluster offset may be an allocated byte offset in the image file, the * zero cluster marker, or the unallocated cluster marker. + * + * Called with table_lock held. */ static void qed_update_l2_table(BDRVQEDState *s, QEDTable *table, int index, unsigned int n, uint64_t cluster) @@ -879,6 +893,7 @@ static void qed_update_l2_table(BDRVQEDState *s, QEDTable *table, int index, } } +/* Called with table_lock held. */ static void qed_aio_complete(QEDAIOCB *acb) { BDRVQEDState *s = acb_to_s(acb); @@ -902,7 +917,7 @@ static void qed_aio_complete(QEDAIOCB *acb) if (acb == s->allocating_acb) { s->allocating_acb = NULL; if (!qemu_co_queue_empty(&s->allocating_write_reqs)) { - qemu_co_enter_next(&s->allocating_write_reqs); + qemu_co_queue_next(&s->allocating_write_reqs); } else if (s->header.features & QED_F_NEED_CHECK) { qed_start_need_check_timer(s); } @@ -911,6 +926,8 @@ static void qed_aio_complete(QEDAIOCB *acb) /** * Update L1 table with new L2 table offset and write it out + * + * Called with table_lock held. */ static int qed_aio_write_l1_update(QEDAIOCB *acb) { @@ -939,6 +956,8 @@ static int qed_aio_write_l1_update(QEDAIOCB *acb) /** * Update L2 table with new cluster offsets and write them out + * + * Called with table_lock held. */ static int qed_aio_write_l2_update(QEDAIOCB *acb, uint64_t offset) { @@ -975,6 +994,8 @@ static int qed_aio_write_l2_update(QEDAIOCB *acb, uint64_t offset) /** * Write data to the image file + * + * Called with table_lock *not* held. */ static int qed_aio_write_main(QEDAIOCB *acb) { @@ -990,6 +1011,8 @@ static int qed_aio_write_main(QEDAIOCB *acb) /** * Populate untouched regions of new data cluster + * + * Called with table_lock held. */ static int qed_aio_write_cow(QEDAIOCB *acb) { @@ -997,6 +1020,8 @@ static int qed_aio_write_cow(QEDAIOCB *acb) uint64_t start, len, offset; int ret; + qemu_co_mutex_unlock(&s->table_lock); + /* Populate front untouched region of new data cluster */ start = qed_start_of_cluster(s, acb->cur_pos); len = qed_offset_into_cluster(s, acb->cur_pos); @@ -1004,7 +1029,7 @@ static int qed_aio_write_cow(QEDAIOCB *acb) trace_qed_aio_write_prefill(s, acb, start, len, acb->cur_cluster); ret = qed_copy_from_backing_file(s, start, len, acb->cur_cluster); if (ret < 0) { - return ret; + goto out; } /* Populate back untouched region of new data cluster */ @@ -1017,12 +1042,12 @@ static int qed_aio_write_cow(QEDAIOCB *acb) trace_qed_aio_write_postfill(s, acb, start, len, offset); ret = qed_copy_from_backing_file(s, start, len, offset); if (ret < 0) { - return ret; + goto out; } ret = qed_aio_write_main(acb); if (ret < 0) { - return ret; + goto out; } if (s->bs->backing) { @@ -1037,12 +1062,11 @@ static int qed_aio_write_cow(QEDAIOCB *acb) * cluster and before updating the L2 table. */ ret = bdrv_flush(s->bs->file->bs); - if (ret < 0) { - return ret; - } } - return 0; +out: + qemu_co_mutex_lock(&s->table_lock); + return ret; } /** @@ -1065,6 +1089,8 @@ static bool qed_should_set_need_check(BDRVQEDState *s) * @len: Length in bytes * * This path is taken when writing to previously unallocated clusters. + * + * Called with table_lock held. */ static int qed_aio_write_alloc(QEDAIOCB *acb, size_t len) { @@ -1079,7 +1105,7 @@ static int qed_aio_write_alloc(QEDAIOCB *acb, size_t len) /* Freeze this request if another allocating write is in progress */ if (s->allocating_acb != acb || s->allocating_write_reqs_plugged) { if (s->allocating_acb != NULL) { - qemu_co_queue_wait(&s->allocating_write_reqs, NULL); + qemu_co_queue_wait(&s->allocating_write_reqs, &s->table_lock); assert(s->allocating_acb == NULL); } s->allocating_acb = acb; @@ -1126,9 +1152,16 @@ static int qed_aio_write_alloc(QEDAIOCB *acb, size_t len) * @len: Length in bytes * * This path is taken when writing to already allocated clusters. + * + * Called with table_lock held. */ static int qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset, size_t len) { + BDRVQEDState *s = acb_to_s(acb); + int r; + + qemu_co_mutex_unlock(&s->table_lock); + /* Allocate buffer for zero writes */ if (acb->flags & QED_AIOCB_ZERO) { struct iovec *iov = acb->qiov->iov; @@ -1136,7 +1169,8 @@ static int qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset, size_t len) if (!iov->iov_base) { iov->iov_base = qemu_try_blockalign(acb->bs, iov->iov_len); if (iov->iov_base == NULL) { - return -ENOMEM; + r = -ENOMEM; + goto out; } memset(iov->iov_base, 0, iov->iov_len); } @@ -1146,8 +1180,11 @@ static int qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset, size_t len) acb->cur_cluster = offset; qemu_iovec_concat(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); - /* Do the actual write */ - return qed_aio_write_main(acb); + /* Do the actual write. */ + r = qed_aio_write_main(acb); +out: + qemu_co_mutex_lock(&s->table_lock); + return r; } /** @@ -1158,7 +1195,7 @@ static int qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset, size_t len) * @offset: Cluster offset in bytes * @len: Length in bytes * - * Callback from qed_find_cluster(). + * Called with table_lock held. */ static int qed_aio_write_data(void *opaque, int ret, uint64_t offset, size_t len) @@ -1191,13 +1228,16 @@ static int qed_aio_write_data(void *opaque, int ret, * @offset: Cluster offset in bytes * @len: Length in bytes * - * Callback from qed_find_cluster(). + * Called with table_lock held. */ static int qed_aio_read_data(void *opaque, int ret, uint64_t offset, size_t len) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); BlockDriverState *bs = acb->bs; + int r; + + qemu_co_mutex_unlock(&s->table_lock); /* Adjust offset into cluster */ offset += qed_offset_into_cluster(s, acb->cur_pos); @@ -1206,21 +1246,22 @@ static int qed_aio_read_data(void *opaque, int ret, uint64_t offset, size_t len) qemu_iovec_concat(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); - /* Handle zero cluster and backing file reads */ + /* Handle zero cluster and backing file reads, otherwise read + * data cluster directly. + */ if (ret == QED_CLUSTER_ZERO) { qemu_iovec_memset(&acb->cur_qiov, 0, 0, acb->cur_qiov.size); - return 0; + r = 0; } else if (ret != QED_CLUSTER_FOUND) { - return qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov, - &acb->backing_qiov); + r = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov, + &acb->backing_qiov); + } else { + BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); + r = bdrv_preadv(bs->file, offset, &acb->cur_qiov); } - BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); - ret = bdrv_preadv(bs->file, offset, &acb->cur_qiov); - if (ret < 0) { - return ret; - } - return 0; + qemu_co_mutex_lock(&s->table_lock); + return r; } /** @@ -1233,6 +1276,7 @@ static int qed_aio_next_io(QEDAIOCB *acb) size_t len; int ret; + qemu_co_mutex_lock(&s->table_lock); while (1) { trace_qed_aio_next_io(s, acb, 0, acb->cur_pos + acb->cur_qiov.size); @@ -1272,6 +1316,7 @@ static int qed_aio_next_io(QEDAIOCB *acb) trace_qed_aio_complete(s, acb, ret); qed_aio_complete(acb); + qemu_co_mutex_unlock(&s->table_lock); return ret; } diff --git a/block/qed.h b/block/qed.h index fb80943c2d..21a338cdd5 100644 --- a/block/qed.h +++ b/block/qed.h @@ -151,15 +151,21 @@ typedef struct QEDAIOCB { typedef struct { BlockDriverState *bs; /* device */ - uint64_t file_size; /* length of image file, in bytes */ + /* Written only by an allocating write or the timer handler (the latter + * while allocating reqs are plugged). + */ QEDHeader header; /* always cpu-endian */ + + /* Protected by table_lock. */ + CoMutex table_lock; QEDTable *l1_table; L2TableCache l2_cache; /* l2 table cache */ uint32_t table_nelems; uint32_t l1_shift; uint32_t l2_shift; uint32_t l2_mask; + uint64_t file_size; /* length of image file, in bytes */ /* Allocating write request queue */ QEDAIOCB *allocating_acb; @@ -177,9 +183,6 @@ enum { QED_CLUSTER_L1, /* cluster missing in L1 */ }; -void qed_acquire(BDRVQEDState *s); -void qed_release(BDRVQEDState *s); - /** * Header functions */ -- 2.13.0