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Kernel: Make StorageDevice partial block writes OOM-fallible

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This commit is contained in:
Idan Horowitz 2022-01-25 14:58:47 +02:00
parent 6f8e89a905
commit daf6b59a01
1 changed files with 8 additions and 5 deletions
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13
Kernel/Storage/StorageDevice.cpp
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@ -105,6 +105,12 @@ ErrorOr<size_t> StorageDevice::write(OpenFileDescription&, u64 offset, const Use
remaining = 0; remaining = 0;
} }
// We try to allocate the temporary block buffer for partial writes *before* we start any full block writes,
// to try and prevent partial writes
Optional<ByteBuffer> partial_write_block;
if (remaining > 0)
partial_write_block = TRY(ByteBuffer::create_zeroed(block_size()));
dbgln_if(STORAGE_DEVICE_DEBUG, "StorageDevice::write() index={}, whole_blocks={}, remaining={}", index, whole_blocks, remaining); dbgln_if(STORAGE_DEVICE_DEBUG, "StorageDevice::write() index={}, whole_blocks={}, remaining={}", index, whole_blocks, remaining);
if (whole_blocks > 0) { if (whole_blocks > 0) {
@ -129,10 +135,7 @@ ErrorOr<size_t> StorageDevice::write(OpenFileDescription&, u64 offset, const Use
// partial write, we have to read the block's content first, modify it, // partial write, we have to read the block's content first, modify it,
// then write the whole block back to the disk. // then write the whole block back to the disk.
if (remaining > 0) { if (remaining > 0) {
// FIXME: Do something sensible with this OOM scenario. auto data_buffer = UserOrKernelBuffer::for_kernel_buffer(partial_write_block->data());
auto data = ByteBuffer::create_zeroed(block_size()).release_value_but_fixme_should_propagate_errors();
auto data_buffer = UserOrKernelBuffer::for_kernel_buffer(data.data());
{ {
auto read_request = TRY(try_make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Read, index + whole_blocks, 1, data_buffer, block_size())); auto read_request = TRY(try_make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Read, index + whole_blocks, 1, data_buffer, block_size()));
auto result = read_request->wait(); auto result = read_request->wait();
@ -151,7 +154,7 @@ ErrorOr<size_t> StorageDevice::write(OpenFileDescription&, u64 offset, const Use
} }
} }
TRY(inbuf.read(data.data(), pos, remaining)); TRY(inbuf.read(partial_write_block->data(), pos, remaining));
{ {
auto write_request = TRY(try_make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Write, index + whole_blocks, 1, data_buffer, block_size())); auto write_request = TRY(try_make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Write, index + whole_blocks, 1, data_buffer, block_size()));