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[dev][virtio-block] fix bug when not using paging

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In the non VM path the existing routine wouldn't subtract from len, so
the function would (properly) return bytes transferred instead of zero.

The wrapping code was written to assume 0 and not bytes transferred,
which seemed like a workaround for broken code. Change the inner routine
to always return bytes transferred and adjust wrapper routines
accordingly.
This commit is contained in:
Travis Geiselbrecht
2022-04-25 23:37:39 -07:00
parent 1c9caf9f64
commit b834181637
1 changed files with 19 additions and 18 deletions
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37
dev/virtio/block/virtio-block.c
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@@ -190,7 +190,7 @@ static enum handler_return virtio_block_irq_driver_callback(struct virtio_device
return INT_RESCHEDULE;
}
ssize_t virtio_block_read_write(struct virtio_device *dev, void *buf, off_t offset, size_t len, bool write) {
ssize_t virtio_block_read_write(struct virtio_device *dev, void *buf, const off_t offset, const size_t len, const bool write) {
struct virtio_block_dev *bdev = (struct virtio_block_dev *)dev->priv;
uint16_t i;
@@ -228,6 +228,7 @@ ssize_t virtio_block_read_write(struct virtio_device *dev, void *buf, off_t offs
desc->addr = (uint64_t)pa;
/* desc->len is filled in below */
#else
/* non VM world simply queues a single buffer that transfers the whole thing */
desc->addr = (uint64_t)(uintptr_t)buf;
desc->len = len;
#endif
@@ -239,21 +240,25 @@ ssize_t virtio_block_read_write(struct virtio_device *dev, void *buf, off_t offs
paddr_t next_pa = PAGE_ALIGN(pa + 1);
desc->len = MIN(next_pa - pa, len);
LTRACEF("first descriptor va 0x%lx desc->addr 0x%llx desc->len %u\n", va, desc->addr, desc->len);
len -= desc->len;
while (len > 0) {
size_t remaining_len = len;
remaining_len -= desc->len;
while (remaining_len > 0) {
/* amount of source buffer handled by this iteration of the loop */
size_t len_tohandle = MIN(len, PAGE_SIZE);
size_t len_tohandle = MIN(remaining_len, PAGE_SIZE);
/* translate the next page in the buffer */
va = PAGE_ALIGN(va + 1);
pa = vaddr_to_paddr((void *)va);
LTRACEF("va now 0x%lx, pa 0x%lx, next_pa 0x%lx, remaining len %zu\n", va, pa, next_pa, len);
LTRACEF("va now 0x%lx, pa 0x%lx, next_pa 0x%lx, remaining len %zu\n", va, pa, next_pa, remaining_len);
/* is the new translated physical address contiguous to the last one? */
if (next_pa == pa) {
/* we can simply extend the previous descriptor by another page */
LTRACEF("extending last one by %zu bytes\n", len_tohandle);
desc->len += len_tohandle;
} else {
/* new physical page needed, allocate a new descriptor and start again */
uint16_t next_i = virtio_alloc_desc(dev, 0);
struct vring_desc *next_desc = virtio_desc_index_to_desc(dev, 0, next_i);
DEBUG_ASSERT(next_desc);
@@ -270,7 +275,7 @@ ssize_t virtio_block_read_write(struct virtio_device *dev, void *buf, off_t offs
desc = next_desc;
}
len -= len_tohandle;
remaining_len -= len_tohandle;
next_pa += PAGE_SIZE;
}
#endif
@@ -292,6 +297,8 @@ ssize_t virtio_block_read_write(struct virtio_device *dev, void *buf, off_t offs
LTRACEF("status 0x%hhx\n", bdev->blk_response);
/* TODO: handle transfer errors and return error */
mutex_release(&bdev->lock);
return len;
@@ -302,12 +309,9 @@ static ssize_t virtio_bdev_read_block(struct bdev *bdev, void *buf, bnum_t block
LTRACEF("dev %p, buf %p, block 0x%x, count %u\n", bdev, buf, block, count);
if (virtio_block_read_write(dev->dev, buf, (off_t)block * dev->bdev.block_size,
count * dev->bdev.block_size, false) == 0) {
return count * dev->bdev.block_size;
} else {
return ERR_IO;
}
ssize_t result = virtio_block_read_write(dev->dev, buf, (off_t)block * dev->bdev.block_size,
count * dev->bdev.block_size, false);
return result;
}
static ssize_t virtio_bdev_write_block(struct bdev *bdev, const void *buf, bnum_t block, uint count) {
@@ -315,11 +319,8 @@ static ssize_t virtio_bdev_write_block(struct bdev *bdev, const void *buf, bnum_
LTRACEF("dev %p, buf %p, block 0x%x, count %u\n", bdev, buf, block, count);
if (virtio_block_read_write(dev->dev, (void *)buf, (off_t)block * dev->bdev.block_size,
count * dev->bdev.block_size, true) == 0) {
return count * dev->bdev.block_size;
} else {
return ERR_IO;
}
ssize_t result = virtio_block_read_write(dev->dev, (void *)buf, (off_t)block * dev->bdev.block_size,
count * dev->bdev.block_size, true);
return result;
}