block: clarify the meaning of BDRV_O_NOCACHE
Change BDRV_O_NOCACHE to only imply bypassing the host OS file cache, but no writeback semantics. All existing callers are changed to also specify BDRV_O_CACHE_WB to give them writeback semantics. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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parent
69c38b8fce
commit
a659979328
8
block.c
8
block.c
@ -439,13 +439,7 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
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bs->drv = drv;
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bs->drv = drv;
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bs->opaque = qemu_mallocz(drv->instance_size);
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bs->opaque = qemu_mallocz(drv->instance_size);
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/*
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if (flags & BDRV_O_CACHE_WB)
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* Yes, BDRV_O_NOCACHE aka O_DIRECT means we have to present a
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* write cache to the guest. We do need the fdatasync to flush
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* out transactions for block allocations, and we maybe have a
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* volatile write cache in our backing device to deal with.
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*/
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if (flags & (BDRV_O_CACHE_WB|BDRV_O_NOCACHE))
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bs->enable_write_cache = 1;
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bs->enable_write_cache = 1;
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/*
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/*
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@ -229,7 +229,7 @@ static int qcow2_open(BlockDriverState *bs, int flags)
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}
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}
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/* alloc L2 table/refcount block cache */
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/* alloc L2 table/refcount block cache */
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writethrough = ((flags & BDRV_O_CACHE_MASK) == 0);
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writethrough = ((flags & BDRV_O_CACHE_WB) == 0);
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s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE, writethrough);
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s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE, writethrough);
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s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE,
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s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE,
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writethrough);
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writethrough);
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@ -154,7 +154,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
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* and O_DIRECT for no caching. */
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* and O_DIRECT for no caching. */
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if ((bdrv_flags & BDRV_O_NOCACHE))
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if ((bdrv_flags & BDRV_O_NOCACHE))
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s->open_flags |= O_DIRECT;
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s->open_flags |= O_DIRECT;
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else if (!(bdrv_flags & BDRV_O_CACHE_WB))
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if (!(bdrv_flags & BDRV_O_CACHE_WB))
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s->open_flags |= O_DSYNC;
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s->open_flags |= O_DSYNC;
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s->fd = -1;
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s->fd = -1;
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@ -88,9 +88,9 @@ static int raw_open(BlockDriverState *bs, const char *filename, int flags)
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}
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}
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overlapped = FILE_ATTRIBUTE_NORMAL;
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overlapped = FILE_ATTRIBUTE_NORMAL;
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if ((flags & BDRV_O_NOCACHE))
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if (flags & BDRV_O_NOCACHE)
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overlapped |= FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH;
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overlapped |= FILE_FLAG_NO_BUFFERING;
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else if (!(flags & BDRV_O_CACHE_WB))
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if (!(flags & BDRV_O_CACHE_WB))
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overlapped |= FILE_FLAG_WRITE_THROUGH;
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overlapped |= FILE_FLAG_WRITE_THROUGH;
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s->hfile = CreateFile(filename, access_flags,
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s->hfile = CreateFile(filename, access_flags,
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FILE_SHARE_READ, NULL,
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FILE_SHARE_READ, NULL,
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@ -349,9 +349,9 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
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create_flags = OPEN_EXISTING;
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create_flags = OPEN_EXISTING;
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overlapped = FILE_ATTRIBUTE_NORMAL;
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overlapped = FILE_ATTRIBUTE_NORMAL;
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if ((flags & BDRV_O_NOCACHE))
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if (flags & BDRV_O_NOCACHE)
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overlapped |= FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH;
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overlapped |= FILE_FLAG_NO_BUFFERING;
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else if (!(flags & BDRV_O_CACHE_WB))
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if (!(flags & BDRV_O_CACHE_WB))
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overlapped |= FILE_FLAG_WRITE_THROUGH;
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overlapped |= FILE_FLAG_WRITE_THROUGH;
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s->hfile = CreateFile(filename, access_flags,
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s->hfile = CreateFile(filename, access_flags,
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FILE_SHARE_READ, NULL,
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FILE_SHARE_READ, NULL,
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@ -326,7 +326,7 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
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if ((buf = qemu_opt_get(opts, "cache")) != NULL) {
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if ((buf = qemu_opt_get(opts, "cache")) != NULL) {
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if (!strcmp(buf, "off") || !strcmp(buf, "none")) {
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if (!strcmp(buf, "off") || !strcmp(buf, "none")) {
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bdrv_flags |= BDRV_O_NOCACHE;
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bdrv_flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
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} else if (!strcmp(buf, "writeback")) {
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} else if (!strcmp(buf, "writeback")) {
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bdrv_flags |= BDRV_O_CACHE_WB;
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bdrv_flags |= BDRV_O_CACHE_WB;
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} else if (!strcmp(buf, "unsafe")) {
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} else if (!strcmp(buf, "unsafe")) {
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@ -1655,7 +1655,7 @@ open_f(int argc, char **argv)
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flags |= BDRV_O_SNAPSHOT;
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flags |= BDRV_O_SNAPSHOT;
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break;
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break;
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case 'n':
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case 'n':
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flags |= BDRV_O_NOCACHE;
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flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
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break;
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break;
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case 'r':
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case 'r':
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readonly = 1;
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readonly = 1;
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@ -1751,7 +1751,7 @@ int main(int argc, char **argv)
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flags |= BDRV_O_SNAPSHOT;
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flags |= BDRV_O_SNAPSHOT;
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break;
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break;
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case 'n':
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case 'n':
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flags |= BDRV_O_NOCACHE;
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flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
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break;
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break;
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case 'c':
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case 'c':
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add_user_command(optarg);
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add_user_command(optarg);
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@ -238,7 +238,7 @@ int main(int argc, char **argv)
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flags |= BDRV_O_SNAPSHOT;
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flags |= BDRV_O_SNAPSHOT;
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break;
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break;
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case 'n':
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case 'n':
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flags |= BDRV_O_NOCACHE;
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flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
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break;
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break;
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case 'b':
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case 'b':
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bindto = optarg;
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bindto = optarg;
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