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dev: implement reading from block devices

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reading from block devices is done using the block cache (bcache).
This cache stores sectors from a block device in pages of memory
marked as 'cached', which will allow them to be reclaimed when
memory pressure is high (TODO).

while block device drivers implement callbacks allowing reading/writing
at block-granularity, the device subsystem uses the block cache to
implement reading/writing at byte-granularity in a driver-agnostic way.

block drivers can disable the block cache for their devices, but this
will require that any clients communicate with the devices at
block-granularity.

also added an offset parameter to device and object read/write functions/callbacks.
This commit is contained in:
max 🍓
2023-07-09 21:58:40 +01:00
parent 53440653f2
commit 3233169f25
14 changed files with 435 additions and 52 deletions
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8
dev/char.c
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@@ -18,25 +18,25 @@ struct char_device *char_device_from_generic(struct device *dev)
return CHAR_DEVICE(dev);
}
static kern_status_t char_device_read(struct device *dev, void *buf, size_t size, size_t *bytes_read, socks_flags_t flags)
static kern_status_t char_device_read(struct device *dev, void *buf, size_t offset, size_t size, size_t *bytes_read, socks_flags_t flags)
{
kern_status_t status = KERN_UNSUPPORTED;
struct char_device *cdev = CHAR_DEVICE(dev);
if (cdev->c_ops && cdev->c_ops->read) {
status = cdev->c_ops->read(dev, buf, size, bytes_read, flags);
status = cdev->c_ops->read(dev, buf, offset, size, bytes_read, flags);
}
return status;
}
static kern_status_t char_device_write(struct device *dev, const void *buf, size_t size, size_t *bytes_read, socks_flags_t flags)
static kern_status_t char_device_write(struct device *dev, const void *buf, size_t offset, size_t size, size_t *bytes_read, socks_flags_t flags)
{
kern_status_t status = KERN_UNSUPPORTED;
struct char_device *cdev = CHAR_DEVICE(dev);
if (cdev->c_ops && cdev->c_ops->write) {
status = cdev->c_ops->write(dev, buf, size, bytes_read, flags);
status = cdev->c_ops->write(dev, buf, offset, size, bytes_read, flags);
}
return status;