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blockdev: drain while unlocked in external_snapshot_action()

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This is in preparation to mark bdrv_drained_begin() as GRAPH_UNLOCKED.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20250530151125.955508-19-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Fiona Ebner 2025-05-30 17:10:55 +02:00 • committed by Kevin Wolf
parent 6f101614f9
commit 195a8a946a
1 changed files with 16 additions and 1 deletions
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17
blockdev.c
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@ -1377,9 +1377,10 @@ static void external_snapshot_action(TransactionAction *action,
const char *new_image_file; const char *new_image_file;
ExternalSnapshotState *state = g_new0(ExternalSnapshotState, 1); ExternalSnapshotState *state = g_new0(ExternalSnapshotState, 1);
uint64_t perm, shared; uint64_t perm, shared;
BlockDriverState *check_bs;
/* TODO We'll eventually have to take a writer lock in this function */ /* TODO We'll eventually have to take a writer lock in this function */
GRAPH_RDLOCK_GUARD_MAINLOOP(); bdrv_graph_rdlock_main_loop();
tran_add(tran, &external_snapshot_drv, state); tran_add(tran, &external_snapshot_drv, state);
@ -1412,11 +1413,25 @@ static void external_snapshot_action(TransactionAction *action,
state->old_bs = bdrv_lookup_bs(device, node_name, errp); state->old_bs = bdrv_lookup_bs(device, node_name, errp);
if (!state->old_bs) { if (!state->old_bs) {
bdrv_graph_rdunlock_main_loop();
return; return;
} }
/* Need to drain while unlocked. */
bdrv_graph_rdunlock_main_loop();
/* Paired with .clean() */ /* Paired with .clean() */
bdrv_drained_begin(state->old_bs); bdrv_drained_begin(state->old_bs);
GRAPH_RDLOCK_GUARD_MAINLOOP();
/* Make sure the associated bs did not change with the drain. */
check_bs = bdrv_lookup_bs(device, node_name, errp);
if (state->old_bs != check_bs) {
if (check_bs) {
error_setg(errp, "Block node of device '%s' unexpectedly changed",
device);
} /* else errp is already set */
return;
}
if (!bdrv_is_inserted(state->old_bs)) { if (!bdrv_is_inserted(state->old_bs)) {
error_setg(errp, "Device '%s' has no medium", error_setg(errp, "Device '%s' has no medium",