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block: Call .bdrv_co_create(_opts) unlocked

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These are functions that modify the graph, so they must be able to take
a writer lock. This is impossible if they already hold the reader lock.
If they need a reader lock for some of their operations, they should
take it internally.

Many of them go through blk_*(), which will always take the lock itself.
Direct calls of bdrv_*() need to take the reader lock. Note that while
locking for bdrv_co_*() calls is checked by TSA, this is not the case
for the mixed_coroutine_fns bdrv_*(). Holding the lock is still required
when they are called from coroutine context like here!

This effectively reverts 4ec8df0183, but adds some internal locking
instead.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230510203601.418015-2-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2023-05-10 22:35:54 +02:00
parent 41f8b63339
commit 4db7ba3b87
14 changed files with 78 additions and 70 deletions
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37
block/qcow2.c
View file

@ -118,8 +118,9 @@ static int qcow2_crypto_hdr_read_func(QCryptoBlock *block, size_t offset,
}
static int qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen,
void *opaque, Error **errp)
static int coroutine_fn GRAPH_RDLOCK
qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen, void *opaque,
Error **errp)
{
BlockDriverState *bs = opaque;
BDRVQcow2State *s = bs->opaque;
@ -144,9 +145,7 @@ static int qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen,
*/
clusterlen = size_to_clusters(s, headerlen) * s->cluster_size;
assert(qcow2_pre_write_overlap_check(bs, 0, ret, clusterlen, false) == 0);
ret = bdrv_pwrite_zeroes(bs->file,
ret,
clusterlen, 0);
ret = bdrv_co_pwrite_zeroes(bs->file, ret, clusterlen, 0);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not zero fill encryption header");
return -1;
@ -156,9 +155,11 @@ static int qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen,
}
static int qcow2_crypto_hdr_write_func(QCryptoBlock *block, size_t offset,
const uint8_t *buf, size_t buflen,
void *opaque, Error **errp)
/* The graph lock must be held when called in coroutine context */
static int coroutine_mixed_fn
qcow2_crypto_hdr_write_func(QCryptoBlock *block, size_t offset,
const uint8_t *buf, size_t buflen,
void *opaque, Error **errp)
{
BlockDriverState *bs = opaque;
BDRVQcow2State *s = bs->opaque;
@ -3137,9 +3138,10 @@ static int qcow2_change_backing_file(BlockDriverState *bs,
return qcow2_update_header(bs);
}
static int qcow2_set_up_encryption(BlockDriverState *bs,
QCryptoBlockCreateOptions *cryptoopts,
Error **errp)
static int coroutine_fn GRAPH_RDLOCK
qcow2_set_up_encryption(BlockDriverState *bs,
QCryptoBlockCreateOptions *cryptoopts,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
QCryptoBlock *crypto = NULL;
@ -3426,7 +3428,7 @@ static uint64_t qcow2_opt_get_refcount_bits_del(QemuOpts *opts, int version,
return refcount_bits;
}
static int coroutine_fn
static int coroutine_fn GRAPH_UNLOCKED
qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
{
BlockdevCreateOptionsQcow2 *qcow2_opts;
@ -3724,8 +3726,10 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
goto out;
}
bdrv_graph_co_rdlock();
ret = qcow2_alloc_clusters(blk_bs(blk), 3 * cluster_size);
if (ret < 0) {
bdrv_graph_co_rdunlock();
error_setg_errno(errp, -ret, "Could not allocate clusters for qcow2 "
"header and refcount table");
goto out;
@ -3743,6 +3747,8 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
/* Create a full header (including things like feature table) */
ret = qcow2_update_header(blk_bs(blk));
bdrv_graph_co_rdunlock();
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not update qcow2 header");
goto out;
@ -3776,7 +3782,10 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
/* Want encryption? There you go. */
if (qcow2_opts->encrypt) {
bdrv_graph_co_rdlock();
ret = qcow2_set_up_encryption(blk_bs(blk), qcow2_opts->encrypt, errp);
bdrv_graph_co_rdunlock();
if (ret < 0) {
goto out;
}
@ -3813,7 +3822,7 @@ out:
return ret;
}
static int coroutine_fn GRAPH_RDLOCK
static int coroutine_fn GRAPH_UNLOCKED
qcow2_co_create_opts(BlockDriver *drv, const char *filename, QemuOpts *opts,
Error **errp)
{
@ -3933,8 +3942,10 @@ qcow2_co_create_opts(BlockDriver *drv, const char *filename, QemuOpts *opts,
ret = qcow2_co_create(create_options, errp);
finish:
if (ret < 0) {
bdrv_graph_co_rdlock();
bdrv_co_delete_file_noerr(bs);
bdrv_co_delete_file_noerr(data_bs);
bdrv_graph_co_rdunlock();
} else {
ret = 0;
}