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-rw-r--r--block/block-backend.c6
-rw-r--r--hmp.c26
-rw-r--r--include/qemu-io.h1
-rw-r--r--include/sysemu/block-backend.h1
-rw-r--r--qemu-io-cmds.c28
5 files changed, 61 insertions, 1 deletions
diff --git a/block/block-backend.c b/block/block-backend.c
index 38a3858e96..daa7908d01 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -584,6 +584,12 @@ int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
return 0;
}
+void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm)
+{
+ *perm = blk->perm;
+ *shared_perm = blk->shared_perm;
+}
+
static int blk_do_attach_dev(BlockBackend *blk, void *dev)
{
if (blk->dev) {
diff --git a/hmp.c b/hmp.c
index e219f97239..7b44e64c84 100644
--- a/hmp.c
+++ b/hmp.c
@@ -2051,7 +2051,6 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict)
if (!blk) {
BlockDriverState *bs = bdrv_lookup_bs(NULL, device, &err);
if (bs) {
- /* FIXME Use real permissions */
blk = local_blk = blk_new(0, BLK_PERM_ALL);
ret = blk_insert_bs(blk, bs, &err);
if (ret < 0) {
@@ -2065,6 +2064,31 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict)
aio_context = blk_get_aio_context(blk);
aio_context_acquire(aio_context);
+ /*
+ * Notably absent: Proper permission management. This is sad, but it seems
+ * almost impossible to achieve without changing the semantics and thereby
+ * limiting the use cases of the qemu-io HMP command.
+ *
+ * In an ideal world we would unconditionally create a new BlockBackend for
+ * qemuio_command(), but we have commands like 'reopen' and want them to
+ * take effect on the exact BlockBackend whose name the user passed instead
+ * of just on a temporary copy of it.
+ *
+ * Another problem is that deleting the temporary BlockBackend involves
+ * draining all requests on it first, but some qemu-iotests cases want to
+ * issue multiple aio_read/write requests and expect them to complete in
+ * the background while the monitor has already returned.
+ *
+ * This is also what prevents us from saving the original permissions and
+ * restoring them later: We can't revoke permissions until all requests
+ * have completed, and we don't know when that is nor can we really let
+ * anything else run before we have revoken them to avoid race conditions.
+ *
+ * What happens now is that command() in qemu-io-cmds.c can extend the
+ * permissions if necessary for the qemu-io command. And they simply stay
+ * extended, possibly resulting in a read-only guest device keeping write
+ * permissions. Ugly, but it appears to be the lesser evil.
+ */
qemuio_command(blk, command);
aio_context_release(aio_context);
diff --git a/include/qemu-io.h b/include/qemu-io.h
index 4d402b9b01..196fde0f3a 100644
--- a/include/qemu-io.h
+++ b/include/qemu-io.h
@@ -36,6 +36,7 @@ typedef struct cmdinfo {
const char *args;
const char *oneline;
helpfunc_t help;
+ uint64_t perm;
} cmdinfo_t;
extern bool qemuio_misalign;
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index b23f6830db..096c17fce0 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -107,6 +107,7 @@ bool bdrv_has_blk(BlockDriverState *bs);
bool bdrv_is_root_node(BlockDriverState *bs);
int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
Error **errp);
+void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm);
void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
void blk_iostatus_enable(BlockBackend *blk);
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 7ac1576d4c..2c48f9ce1a 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -83,6 +83,29 @@ static int command(BlockBackend *blk, const cmdinfo_t *ct, int argc,
}
return 0;
}
+
+ /* Request additional permissions if necessary for this command. The caller
+ * is responsible for restoring the original permissions afterwards if this
+ * is what it wants. */
+ if (ct->perm && blk_is_available(blk)) {
+ uint64_t orig_perm, orig_shared_perm;
+ blk_get_perm(blk, &orig_perm, &orig_shared_perm);
+
+ if (ct->perm & ~orig_perm) {
+ uint64_t new_perm;
+ Error *local_err = NULL;
+ int ret;
+
+ new_perm = orig_perm | ct->perm;
+
+ ret = blk_set_perm(blk, new_perm, orig_shared_perm, &local_err);
+ if (ret < 0) {
+ error_report_err(local_err);
+ return 0;
+ }
+ }
+ }
+
optind = 0;
return ct->cfunc(blk, argc, argv);
}
@@ -918,6 +941,7 @@ static const cmdinfo_t write_cmd = {
.name = "write",
.altname = "w",
.cfunc = write_f,
+ .perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
.args = "[-bcCfquz] [-P pattern] off len",
@@ -1093,6 +1117,7 @@ static int writev_f(BlockBackend *blk, int argc, char **argv);
static const cmdinfo_t writev_cmd = {
.name = "writev",
.cfunc = writev_f,
+ .perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
.args = "[-Cfq] [-P pattern] off len [len..]",
@@ -1392,6 +1417,7 @@ static int aio_write_f(BlockBackend *blk, int argc, char **argv);
static const cmdinfo_t aio_write_cmd = {
.name = "aio_write",
.cfunc = aio_write_f,
+ .perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
.args = "[-Cfiquz] [-P pattern] off len [len..]",
@@ -1556,6 +1582,7 @@ static const cmdinfo_t truncate_cmd = {
.name = "truncate",
.altname = "t",
.cfunc = truncate_f,
+ .perm = BLK_PERM_WRITE | BLK_PERM_RESIZE,
.argmin = 1,
.argmax = 1,
.args = "off",
@@ -1653,6 +1680,7 @@ static const cmdinfo_t discard_cmd = {
.name = "discard",
.altname = "d",
.cfunc = discard_f,
+ .perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
.args = "[-Cq] off len",