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Kernel/Ext2FS: Reduce allocations in compute_block_list_impl()

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In Ext2FSInode::compute_block_list_impl(), each call to
process_block_array() creates a new ByteBuffer, which leads to a
kmalloc() call. The ByteBuffer is then discarded when
process_block_array() exits, leading to a kfree() call.

This leads to repeated kmalloc() and kfree() calls as ByteBuffers are
created and destroyed each time process_block_array() is called.

This commit makes it so that only 1 ByteBuffer is created for each level
of inode indirect block (so only 3 ByteBuffers are created at most).
These ByteBuffers are re-used on each call to process_block_array().

This reduces the number of kmalloc() and kfree() calls during
compute_block_list_impl(), especially for larger files.
This commit is contained in:
brody-qq 2024-07-14 05:31:17 +01:00 committed by Nico Weber
parent 500ff2a7ed
commit 44a2157e2e
1 changed files with 10 additions and 8 deletions
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18
Kernel/FileSystem/Ext2FS/Inode.cpp
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@ -294,11 +294,11 @@ ErrorOr<Ext2FS::BlockList> Ext2FSInode::compute_block_list_impl(Vector<Ext2FS::B
return {};
};
auto process_block_array = [&](auto current_logical_index, unsigned level, auto array_block_index, auto&& callback) -> ErrorOr<void> {
auto process_block_array = [&](auto current_logical_index, unsigned level, auto array_block_index, ByteBuffer& array_storage, auto&& callback) -> ErrorOr<void> {
if (meta_blocks)
TRY(meta_blocks->try_append(array_block_index));
auto array_storage = TRY(ByteBuffer::create_uninitialized(block_size));
TRY(array_storage.try_resize(block_size));
auto* array = (u32*)array_storage.data();
auto buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)array);
TRY(fs().read_block(array_block_index, &buffer, block_size, 0));
@ -314,24 +314,26 @@ ErrorOr<Ext2FS::BlockList> Ext2FSInode::compute_block_list_impl(Vector<Ext2FS::B
TRY(set_block(i, m_raw_inode.i_block[i]));
}
ByteBuffer block_storage[3] = {};
if (m_raw_inode.i_block[EXT2_IND_BLOCK]) {
TRY(process_block_array(EXT2_NDIR_BLOCKS, 1, m_raw_inode.i_block[EXT2_IND_BLOCK], [&](auto logical_block_index, auto on_disk_index) -> ErrorOr<void> {
TRY(process_block_array(EXT2_NDIR_BLOCKS, 1, m_raw_inode.i_block[EXT2_IND_BLOCK], block_storage[0], [&](auto logical_block_index, auto on_disk_index) -> ErrorOr<void> {
return set_block(logical_block_index, on_disk_index);
}));
}
if (m_raw_inode.i_block[EXT2_DIND_BLOCK]) {
TRY(process_block_array(singly_indirect_block_capacity(), 2, m_raw_inode.i_block[EXT2_DIND_BLOCK], [&](auto logical_block_index, auto on_disk_index) -> ErrorOr<void> {
return process_block_array(logical_block_index, 1, on_disk_index, [&](auto logical_block_index2, auto on_disk_index2) -> ErrorOr<void> {
TRY(process_block_array(singly_indirect_block_capacity(), 2, m_raw_inode.i_block[EXT2_DIND_BLOCK], block_storage[1], [&](auto logical_block_index, auto on_disk_index) -> ErrorOr<void> {
return process_block_array(logical_block_index, 1, on_disk_index, block_storage[0], [&](auto logical_block_index2, auto on_disk_index2) -> ErrorOr<void> {
return set_block(logical_block_index2, on_disk_index2);
});
}));
}
if (m_raw_inode.i_block[EXT2_TIND_BLOCK]) {
TRY(process_block_array(doubly_indirect_block_capacity(), 3, m_raw_inode.i_block[EXT2_TIND_BLOCK], [&](auto logical_block_index, auto on_disk_index) -> ErrorOr<void> {
return process_block_array(logical_block_index, 2, on_disk_index, [&](auto logical_block_index2, auto on_disk_index2) -> ErrorOr<void> {
return process_block_array(logical_block_index2, 1, on_disk_index2, [&](auto logical_block_index3, auto on_disk_index3) -> ErrorOr<void> {
TRY(process_block_array(doubly_indirect_block_capacity(), 3, m_raw_inode.i_block[EXT2_TIND_BLOCK], block_storage[2], [&](auto logical_block_index, auto on_disk_index) -> ErrorOr<void> {
return process_block_array(logical_block_index, 2, on_disk_index, block_storage[1], [&](auto logical_block_index2, auto on_disk_index2) -> ErrorOr<void> {
return process_block_array(logical_block_index2, 1, on_disk_index2, block_storage[0], [&](auto logical_block_index3, auto on_disk_index3) -> ErrorOr<void> {
return set_block(logical_block_index3, on_disk_index3);
});
});