From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38623) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d1Aml-0007aT-I6 for qemu-devel@nongnu.org; Thu, 20 Apr 2017 08:02:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d1AmY-0002vp-Jg for qemu-devel@nongnu.org; Thu, 20 Apr 2017 08:02:07 -0400 From: Paolo Bonzini Date: Thu, 20 Apr 2017 14:00:42 +0200 Message-Id: <20170420120058.28404-2-pbonzini@redhat.com> In-Reply-To: <20170420120058.28404-1-pbonzini@redhat.com> References: <20170420120058.28404-1-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 01/17] block: access copy_on_read with atomic ops List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org Signed-off-by: Paolo Bonzini --- block.c | 6 ++++-- block/io.c | 8 ++++---- blockdev.c | 2 +- include/block/block_int.h | 11 ++++++----- 4 files changed, 15 insertions(+), 12 deletions(-) diff --git a/block.c b/block.c index 1fbbb8d..a48fdd8 100644 --- a/block.c +++ b/block.c @@ -1189,7 +1189,9 @@ static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file, goto fail_opts; } - assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */ + /* bdrv_new() and bdrv_close() make it so */ + assert(atomic_read(&bs->copy_on_read) == 0); + if (bs->open_flags & BDRV_O_COPY_ON_READ) { if (!bs->read_only) { bdrv_enable_copy_on_read(bs); @@ -2937,7 +2939,7 @@ static void bdrv_close(BlockDriverState *bs) g_free(bs->opaque); bs->opaque = NULL; - bs->copy_on_read = 0; + atomic_set(&bs->copy_on_read, 0); bs->backing_file[0] = '\0'; bs->backing_format[0] = '\0'; bs->total_sectors = 0; diff --git a/block/io.c b/block/io.c index a54e5c8..08de488 100644 --- a/block/io.c +++ b/block/io.c @@ -130,13 +130,13 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) */ void bdrv_enable_copy_on_read(BlockDriverState *bs) { - bs->copy_on_read++; + atomic_inc(&bs->copy_on_read); } void bdrv_disable_copy_on_read(BlockDriverState *bs) { - assert(bs->copy_on_read > 0); - bs->copy_on_read--; + assert(atomic_read(&bs->copy_on_read) > 0); + atomic_dec(&bs->copy_on_read); } /* Check if any requests are in-flight (including throttled requests) */ @@ -1144,7 +1144,7 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child, bdrv_inc_in_flight(bs); /* Don't do copy-on-read if we read data before write operation */ - if (bs->copy_on_read && !(flags & BDRV_REQ_NO_SERIALISING)) { + if (atomic_read(&bs->copy_on_read) && !(flags & BDRV_REQ_NO_SERIALISING)) { flags |= BDRV_REQ_COPY_ON_READ; } diff --git a/blockdev.c b/blockdev.c index 9098233..e9b5717 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1794,7 +1794,7 @@ static void external_snapshot_commit(BlkActionState *common) /* We don't need (or want) to use the transactional * bdrv_reopen_multiple() across all the entries at once, because we * don't want to abort all of them if one of them fails the reopen */ - if (!state->old_bs->copy_on_read) { + if (!atomic_read(&state->old_bs->copy_on_read)) { bdrv_reopen(state->old_bs, state->old_bs->open_flags & ~BDRV_O_RDWR, NULL); } diff --git a/include/block/block_int.h b/include/block/block_int.h index 59400bd..d0b88ff 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -581,11 +581,6 @@ struct BlockDriverState { /* Protected by AioContext lock */ - /* If true, copy read backing sectors into image. Can be >1 if more - * than one client has requested copy-on-read. - */ - int copy_on_read; - /* If we are reading a disk image, give its size in sectors. * Generally read-only; it is written to by load_vmstate and save_vmstate, * but the block layer is quiescent during those. @@ -619,6 +614,12 @@ struct BlockDriverState { QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps; + /* If true, copy read backing sectors into image. Can be >1 if more + * than one client has requested copy-on-read. Accessed with atomic + * ops. + */ + int copy_on_read; + /* do we need to tell the quest if we have a volatile write cache? */ int enable_write_cache; -- 2.9.3