diff options
| -rw-r--r-- | block.c | 17 | ||||
| -rw-r--r-- | block/vvfat.c | 1 | ||||
| -rw-r--r-- | blockdev.c | 2 | ||||
| -rw-r--r-- | include/block/block.h | 2 | ||||
| -rw-r--r-- | qapi/block-core.json | 7 |
5 files changed, 28 insertions, 1 deletions
@@ -930,6 +930,7 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options, /* Inherit the read-only option from the parent if it's not set */ qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); + qdict_copy_default(child_options, parent_options, BDRV_OPT_AUTO_READ_ONLY); /* Our block drivers take care to send flushes and respect unmap policy, * so we can default to enable both on lower layers regardless of the @@ -1053,6 +1054,7 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options, /* backing files always opened read-only */ qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on"); + qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off"); flags &= ~BDRV_O_COPY_ON_READ; /* snapshot=on is handled on the top layer */ @@ -1142,6 +1144,10 @@ static void update_flags_from_options(int *flags, QemuOpts *opts) *flags |= BDRV_O_RDWR; } + assert(qemu_opt_find(opts, BDRV_OPT_AUTO_READ_ONLY)); + if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) { + *flags |= BDRV_O_AUTO_RDONLY; + } } static void update_options_from_flags(QDict *options, int flags) @@ -1156,6 +1162,10 @@ static void update_options_from_flags(QDict *options, int flags) if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) { qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR)); } + if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) { + qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY, + flags & BDRV_O_AUTO_RDONLY); + } } static void bdrv_assign_node_name(BlockDriverState *bs, @@ -1329,6 +1339,11 @@ QemuOptsList bdrv_runtime_opts = { .help = "Node is opened in read-only mode", }, { + .name = BDRV_OPT_AUTO_READ_ONLY, + .type = QEMU_OPT_BOOL, + .help = "Node can become read-only if opening read-write fails", + }, + { .name = "detect-zeroes", .type = QEMU_OPT_STRING, .help = "try to optimize zero writes (off, on, unmap)", @@ -2486,6 +2501,8 @@ BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp) qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off"); qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off"); qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off"); + qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off"); + } bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, errp); diff --git a/block/vvfat.c b/block/vvfat.c index f2e7d50..98ba5e2 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -3130,6 +3130,7 @@ static void vvfat_qcow_options(int *child_flags, QDict *child_options, int parent_flags, QDict *parent_options) { qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "off"); + qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off"); qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on"); } @@ -2651,7 +2651,7 @@ void qmp_blockdev_change_medium(bool has_device, const char *device, bdrv_flags = blk_get_open_flags_from_root_state(blk); bdrv_flags &= ~(BDRV_O_TEMPORARY | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | - BDRV_O_PROTOCOL); + BDRV_O_PROTOCOL | BDRV_O_AUTO_RDONLY); if (!has_read_only) { read_only = BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN; diff --git a/include/block/block.h b/include/block/block.h index b189cf4..580b371 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -115,6 +115,7 @@ typedef struct HDGeometry { select an appropriate protocol driver, ignoring the format layer */ #define BDRV_O_NO_IO 0x10000 /* don't initialize for I/O */ +#define BDRV_O_AUTO_RDONLY 0x20000 /* degrade to read-only if opening read-write fails */ #define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_NO_FLUSH) @@ -125,6 +126,7 @@ typedef struct HDGeometry { #define BDRV_OPT_CACHE_DIRECT "cache.direct" #define BDRV_OPT_CACHE_NO_FLUSH "cache.no-flush" #define BDRV_OPT_READ_ONLY "read-only" +#define BDRV_OPT_AUTO_READ_ONLY "auto-read-only" #define BDRV_OPT_DISCARD "discard" #define BDRV_OPT_FORCE_SHARE "force-share" diff --git a/qapi/block-core.json b/qapi/block-core.json index 0fc1590..d4fe710 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -3656,6 +3656,12 @@ # either generally or in certain configurations. In this case, # the default value does not work and the option must be # specified explicitly. +# @auto-read-only: if true and @read-only is false, QEMU may automatically +# decide not to open the image read-write as requested, but +# fall back to read-only instead (and switch between the modes +# later), e.g. depending on whether the image file is writable +# or whether a writing user is attached to the node +# (default: false, since 3.1) # @detect-zeroes: detect and optimize zero writes (Since 2.1) # (default: off) # @force-share: force share all permission on added nodes. @@ -3671,6 +3677,7 @@ '*discard': 'BlockdevDiscardOptions', '*cache': 'BlockdevCacheOptions', '*read-only': 'bool', + '*auto-read-only': 'bool', '*force-share': 'bool', '*detect-zeroes': 'BlockdevDetectZeroesOptions' }, 'discriminator': 'driver', |