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qemu-io: Use bdrv_parse_cache_mode() in reopen_f()

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We must forbid changing the WCE flag in bdrv_reopen() in the same patch,
as otherwise the behaviour would change so that the flag takes
precedence over the explicitly specified option.

The correct value of the WCE flag depends on the BlockBackend user (e.g.
guest device) and isn't a decision that the QMP client makes, so this
change is what we want.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Kevin Wolf 2016-03-18 15:36:31 +01:00
parent 04feb4a507
commit 19dbecdcee
4 changed files with 21 additions and 15 deletions
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18
block.c
View File

@ -2028,18 +2028,12 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
update_flags_from_options(&reopen_state->flags, opts); update_flags_from_options(&reopen_state->flags, opts);
/* If a guest device is attached, it owns WCE */ /* WCE is a BlockBackend level option, can't change it */
if (reopen_state->bs->blk && blk_get_attached_dev(reopen_state->bs->blk)) { bool old_wce = bdrv_enable_write_cache(reopen_state->bs);
bool old_wce = bdrv_enable_write_cache(reopen_state->bs); bool new_wce = (reopen_state->flags & BDRV_O_CACHE_WB);
bool new_wce = (reopen_state->flags & BDRV_O_CACHE_WB);
if (old_wce != new_wce) { if (old_wce != new_wce) {
error_setg(errp, "Cannot change cache.writeback: Device attached"); error_setg(errp, "Cannot change cache.writeback");
ret = -EINVAL;
goto error;
}
}
if (!reopen_state->bs->blk && !(reopen_state->flags & BDRV_O_CACHE_WB)) {
error_setg(errp, "Cannot disable cache.writeback: No BlockBackend");
ret = -EINVAL; ret = -EINVAL;
goto error; goto error;
} }

14
qemu-io-cmds.c
View File

@ -2106,6 +2106,7 @@ static int reopen_f(BlockBackend *blk, int argc, char **argv)
QDict *opts; QDict *opts;
int c; int c;
int flags = bs->open_flags; int flags = bs->open_flags;
bool writethrough = !blk_enable_write_cache(blk);
BlockReopenQueue *brq; BlockReopenQueue *brq;
Error *local_err = NULL; Error *local_err = NULL;
@ -2113,7 +2114,7 @@ static int reopen_f(BlockBackend *blk, int argc, char **argv)
while ((c = getopt(argc, argv, "c:o:r")) != -1) { while ((c = getopt(argc, argv, "c:o:r")) != -1) {
switch (c) { switch (c) {
case 'c': case 'c':
if (bdrv_parse_cache_flags(optarg, &flags) < 0) { if (bdrv_parse_cache_mode(optarg, &flags, &writethrough) < 0) {
error_report("Invalid cache option: %s", optarg); error_report("Invalid cache option: %s", optarg);
return 0; return 0;
} }
@ -2138,14 +2139,25 @@ static int reopen_f(BlockBackend *blk, int argc, char **argv)
return qemuio_command_usage(&reopen_cmd); return qemuio_command_usage(&reopen_cmd);
} }
if (writethrough != blk_enable_write_cache(blk) &&
blk_get_attached_dev(blk))
{
error_report("Cannot change cache.writeback: Device attached");
qemu_opts_reset(&reopen_opts);
return 0;
}
qopts = qemu_opts_find(&reopen_opts, NULL); qopts = qemu_opts_find(&reopen_opts, NULL);
opts = qopts ? qemu_opts_to_qdict(qopts, NULL) : NULL; opts = qopts ? qemu_opts_to_qdict(qopts, NULL) : NULL;
qemu_opts_reset(&reopen_opts); qemu_opts_reset(&reopen_opts);
flags |= blk_enable_write_cache(blk) ? BDRV_O_CACHE_WB : 0;
brq = bdrv_reopen_queue(NULL, bs, opts, flags); brq = bdrv_reopen_queue(NULL, bs, opts, flags);
bdrv_reopen_multiple(brq, &local_err); bdrv_reopen_multiple(brq, &local_err);
if (local_err) { if (local_err) {
error_report_err(local_err); error_report_err(local_err);
} else {
blk_set_enable_write_cache(blk, !writethrough);
} }
return 0; return 0;

2
tests/qemu-iotests/142
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@ -216,7 +216,7 @@ echo
# BDS initialised with the json: pseudo-protocol, but still have it inherit # BDS initialised with the json: pseudo-protocol, but still have it inherit
# options from its parent node. # options from its parent node.
hmp_cmds="qemu-io none0 \"reopen -o cache.writeback=off,cache.direct=on,cache.no-flush=on\" hmp_cmds="qemu-io none0 \"reopen -o cache.direct=on,cache.no-flush=on\"
info block none0 info block none0
info block image info block image
info block blkdebug info block blkdebug

2
tests/qemu-iotests/142.out
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@ -414,7 +414,7 @@ cache.no-flush=on on backing-file
--- Change cache mode in parent, child has explicit option in JSON --- --- Change cache mode in parent, child has explicit option in JSON ---
Cache mode: writethrough, direct, ignore flushes Cache mode: writeback, direct, ignore flushes
Cache mode: writeback, direct, ignore flushes Cache mode: writeback, direct, ignore flushes
Cache mode: writeback, direct, ignore flushes Cache mode: writeback, direct, ignore flushes
Cache mode: writeback, ignore flushes Cache mode: writeback, ignore flushes