The big conversion of bdrv_read/write to coroutines caused the two
homonymous callbacks in BlockDriver to become reentrant. It goes
like this:
1) bdrv_read is now called in a coroutine, and calls bdrv_read or
bdrv_pread.
2) the nested bdrv_read goes through the fast path in bdrv_rw_co_entry;
3) in the common case when the protocol is file, bdrv_co_do_readv calls
bdrv_co_readv_em (and from here goes to bdrv_co_io_em), which yields
until the AIO operation is complete;
4) if bdrv_read had been called from a bottom half, the main loop
is free to iterate again: a device model or another bottom half
can then come and call bdrv_read again.
This applies to all four of read/write/flush/discard. It would also
apply to is_allocated, but it is not used from within coroutines:
besides qemu-img.c and qemu-io.c, which operate synchronously, the
only user is the monitor. Copy-on-read will introduce a use in the
block layer, and will require converting it.
The solution is "simply" to convert all drivers to coroutines! We
just need to add a CoMutex that is taken around affected operations.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block/bochs.c | 2 ++
block/cloop.c | 2 ++
block/cow.c | 2 ++
block/dmg.c | 2 ++
block/nbd.c | 2 ++
block/parallels.c | 2 ++
block/vmdk.c | 2 ++
block/vpc.c | 2 ++
block/vvfat.c | 2 ++
9 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/block/bochs.c b/block/bochs.c
index 3c2f8d1..b0f8072 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -80,6 +80,7 @@ struct bochs_header {
};
typedef struct BDRVBochsState {
+ CoMutex lock;
uint32_t *catalog_bitmap;
int catalog_size;
@@ -150,6 +151,7 @@ static int bochs_open(BlockDriverState *bs, int flags)
s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);
+ qemu_co_mutex_init(&s->lock);
return 0;
fail:
return -1;
diff --git a/block/cloop.c b/block/cloop.c
index 8cff9f2..a91f372 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -27,6 +27,7 @@
#include <zlib.h>
typedef struct BDRVCloopState {
+ CoMutex lock;
uint32_t block_size;
uint32_t n_blocks;
uint64_t* offsets;
@@ -93,6 +94,7 @@ static int cloop_open(BlockDriverState *bs, int flags)
s->sectors_per_block = s->block_size/512;
bs->total_sectors = s->n_blocks*s->sectors_per_block;
+ qemu_co_mutex_init(&s->lock);
return 0;
cloop_close:
diff --git a/block/cow.c b/block/cow.c
index 4cf543c..2f426e7 100644
--- a/block/cow.c
+++ b/block/cow.c
@@ -42,6 +42,7 @@ struct cow_header_v2 {
};
typedef struct BDRVCowState {
+ CoMutex lock;
int64_t cow_sectors_offset;
} BDRVCowState;
@@ -84,6 +85,7 @@ static int cow_open(BlockDriverState *bs, int flags)
bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header);
s->cow_sectors_offset = (bitmap_size + 511) & ~511;
+ qemu_co_mutex_init(&s->lock);
return 0;
fail:
return -1;
diff --git a/block/dmg.c b/block/dmg.c
index 64c3cce..111aeae 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -28,6 +28,7 @@
#include <zlib.h>
typedef struct BDRVDMGState {
+ CoMutex lock;
/* each chunk contains a certain number of sectors,
* offsets[i] is the offset in the .dmg file,
* lengths[i] is the length of the compressed chunk,
@@ -177,6 +178,7 @@ static int dmg_open(BlockDriverState *bs, int flags)
s->current_chunk = s->n_chunks;
+ qemu_co_mutex_init(&s->lock);
return 0;
fail:
return -1;
diff --git a/block/nbd.c b/block/nbd.c
index 76f04d8..14ab225 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -47,6 +47,7 @@
#endif
typedef struct BDRVNBDState {
+ CoMutex lock;
int sock;
uint32_t nbdflags;
off_t size;
@@ -175,6 +176,7 @@ static int nbd_open(BlockDriverState *bs, const char*
filename, int flags)
*/
result = nbd_establish_connection(bs);
+ qemu_co_mutex_init(&s->lock);
return result;
}
diff --git a/block/parallels.c b/block/parallels.c
index c64103d..b86e87e 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -46,6 +46,7 @@ struct parallels_header {
} QEMU_PACKED;
typedef struct BDRVParallelsState {
+ CoMutex lock;
uint32_t *catalog_bitmap;
int catalog_size;
@@ -95,6 +96,7 @@ static int parallels_open(BlockDriverState *bs, int flags)
for (i = 0; i < s->catalog_size; i++)
le32_to_cpus(&s->catalog_bitmap[i]);
+ qemu_co_mutex_init(&s->lock);
return 0;
fail:
if (s->catalog_bitmap)
diff --git a/block/vmdk.c b/block/vmdk.c
index ace2977..1ce220d 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -90,6 +90,7 @@ typedef struct VmdkExtent {
} VmdkExtent;
typedef struct BDRVVmdkState {
+ CoMutex lock;
int desc_offset;
bool cid_updated;
uint32_t parent_cid;
@@ -646,6 +647,7 @@ static int vmdk_open(BlockDriverState *bs, int flags)
goto fail;
}
s->parent_cid = vmdk_read_cid(bs, 1);
+ qemu_co_mutex_init(&s->lock);
return ret;
fail:
diff --git a/block/vpc.c b/block/vpc.c
index 549a632..5414042 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -110,6 +110,7 @@ struct vhd_dyndisk_header {
};
typedef struct BDRVVPCState {
+ CoMutex lock;
uint8_t footer_buf[HEADER_SIZE];
uint64_t free_data_block_offset;
int max_table_entries;
@@ -226,6 +227,7 @@ static int vpc_open(BlockDriverState *bs, int flags)
s->last_pagetable = -1;
#endif
+ qemu_co_mutex_init(&s->lock);
return 0;
fail:
return err;
diff --git a/block/vvfat.c b/block/vvfat.c
index c567697..6f666d6 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -317,6 +317,7 @@ static void print_mapping(const struct mapping_t* mapping);
/* here begins the real VVFAT driver */
typedef struct BDRVVVFATState {
+ CoMutex lock;
BlockDriverState* bs; /* pointer to parent */
unsigned int first_sectors_number; /* 1 for a single partition, 0x40 for a
disk with partition table */
unsigned char first_sectors[0x40*0x200];
@@ -1063,6 +1064,7 @@ DLOG(if (stderr == NULL) {
}
// assert(is_consistent(s));
+ qemu_co_mutex_init(&s->lock);
return 0;
}
--
1.7.6
