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https://github.com/RGBCube/serenity
synced 2025-07-25 21:47:46 +00:00
Kernel: Implement O_DIRECT open() flag to bypass disk caches
Files opened with O_DIRECT will now bypass the disk cache in read/write operations (though metadata operations will still hit the disk cache.) This will allow us to test actual disk performance instead of testing disk *cache* performance, if that's what we want. :^) There's room for improvment here, we're very aggressively flushing any dirty cache entries for the specific block before reading/writing that block. This is done by walking the entire cache, which may be slow.
This commit is contained in:
parent
3de3daf765
commit
59ed235c85
7 changed files with 59 additions and 18 deletions
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@ -1,5 +1,6 @@
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#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/FileSystem/DiskBackedFileSystem.h>
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#include <Kernel/FileSystem/DiskBackedFileSystem.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/KBuffer.h>
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#include <Kernel/KBuffer.h>
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#include <Kernel/Process.h>
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#include <Kernel/Process.h>
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@ -92,11 +93,21 @@ DiskBackedFS::~DiskBackedFS()
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{
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{
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}
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}
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bool DiskBackedFS::write_block(unsigned index, const u8* data)
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bool DiskBackedFS::write_block(unsigned index, const u8* data, FileDescription* description)
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{
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{
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#ifdef DBFS_DEBUG
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#ifdef DBFS_DEBUG
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kprintf("DiskBackedFileSystem::write_block %u, size=%u\n", index, data.size());
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kprintf("DiskBackedFileSystem::write_block %u, size=%u\n", index, data.size());
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#endif
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#endif
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bool allow_cache = !description || !description->is_direct();
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if (!allow_cache) {
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flush_specific_block_if_needed(index);
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DiskOffset base_offset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(block_size());
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device().write(base_offset, block_size(), data);
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return true;
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}
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auto& entry = cache().get(index);
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auto& entry = cache().get(index);
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memcpy(entry.data, data, block_size());
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memcpy(entry.data, data, block_size());
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entry.is_dirty = true;
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entry.is_dirty = true;
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@ -106,22 +117,32 @@ bool DiskBackedFS::write_block(unsigned index, const u8* data)
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return true;
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return true;
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}
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}
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bool DiskBackedFS::write_blocks(unsigned index, unsigned count, const u8* data)
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bool DiskBackedFS::write_blocks(unsigned index, unsigned count, const u8* data, FileDescription* description)
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{
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{
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#ifdef DBFS_DEBUG
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#ifdef DBFS_DEBUG
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kprintf("DiskBackedFileSystem::write_blocks %u x%u\n", index, count);
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kprintf("DiskBackedFileSystem::write_blocks %u x%u\n", index, count);
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#endif
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#endif
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for (unsigned i = 0; i < count; ++i)
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for (unsigned i = 0; i < count; ++i)
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write_block(index + i, data + i * block_size());
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write_block(index + i, data + i * block_size(), description);
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return true;
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return true;
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}
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}
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bool DiskBackedFS::read_block(unsigned index, u8* buffer) const
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bool DiskBackedFS::read_block(unsigned index, u8* buffer, FileDescription* description) const
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{
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{
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#ifdef DBFS_DEBUG
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#ifdef DBFS_DEBUG
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kprintf("DiskBackedFileSystem::read_block %u\n", index);
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kprintf("DiskBackedFileSystem::read_block %u\n", index);
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#endif
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#endif
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bool allow_cache = !description || !description->is_direct();
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if (!allow_cache) {
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const_cast<DiskBackedFS*>(this)->flush_specific_block_if_needed(index);
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DiskOffset base_offset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(block_size());
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bool success = device().read(base_offset, block_size(), buffer);
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ASSERT(success);
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return true;
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}
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auto& entry = cache().get(index);
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auto& entry = cache().get(index);
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if (!entry.has_data) {
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if (!entry.has_data) {
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DiskOffset base_offset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(block_size());
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DiskOffset base_offset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(block_size());
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@ -133,16 +154,16 @@ bool DiskBackedFS::read_block(unsigned index, u8* buffer) const
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return true;
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return true;
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}
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}
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bool DiskBackedFS::read_blocks(unsigned index, unsigned count, u8* buffer) const
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bool DiskBackedFS::read_blocks(unsigned index, unsigned count, u8* buffer, FileDescription* description) const
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{
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{
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if (!count)
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if (!count)
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return false;
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return false;
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if (count == 1)
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if (count == 1)
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return read_block(index, buffer);
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return read_block(index, buffer, description);
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u8* out = buffer;
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u8* out = buffer;
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for (unsigned i = 0; i < count; ++i) {
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for (unsigned i = 0; i < count; ++i) {
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if (!read_block(index + i, out))
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if (!read_block(index + i, out, description))
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return false;
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return false;
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out += block_size();
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out += block_size();
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}
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}
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@ -150,6 +171,20 @@ bool DiskBackedFS::read_blocks(unsigned index, unsigned count, u8* buffer) const
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return true;
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return true;
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}
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}
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void DiskBackedFS::flush_specific_block_if_needed(unsigned index)
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{
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LOCKER(m_lock);
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if (!cache().is_dirty())
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return;
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cache().for_each_entry([&](CacheEntry& entry) {
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if (entry.is_dirty && entry.block_index == index) {
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DiskOffset base_offset = static_cast<DiskOffset>(entry.block_index) * static_cast<DiskOffset>(block_size());
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device().write(base_offset, block_size(), entry.data);
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entry.is_dirty = false;
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}
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});
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}
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void DiskBackedFS::flush_writes_impl()
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void DiskBackedFS::flush_writes_impl()
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{
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{
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LOCKER(m_lock);
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LOCKER(m_lock);
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@ -21,14 +21,15 @@ public:
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protected:
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protected:
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explicit DiskBackedFS(NonnullRefPtr<DiskDevice>&&);
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explicit DiskBackedFS(NonnullRefPtr<DiskDevice>&&);
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bool read_block(unsigned index, u8* buffer) const;
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bool read_block(unsigned index, u8* buffer, FileDescription* = nullptr) const;
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bool read_blocks(unsigned index, unsigned count, u8* buffer) const;
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bool read_blocks(unsigned index, unsigned count, u8* buffer, FileDescription* = nullptr) const;
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bool write_block(unsigned index, const u8*);
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bool write_block(unsigned index, const u8*, FileDescription* = nullptr);
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bool write_blocks(unsigned index, unsigned count, const u8*);
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bool write_blocks(unsigned index, unsigned count, const u8*, FileDescription* = nullptr);
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private:
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private:
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DiskCache& cache() const;
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DiskCache& cache() const;
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void flush_specific_block_if_needed(unsigned index);
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NonnullRefPtr<DiskDevice> m_device;
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NonnullRefPtr<DiskDevice> m_device;
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mutable OwnPtr<DiskCache> m_cache;
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mutable OwnPtr<DiskCache> m_cache;
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@ -2,6 +2,7 @@
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#include <AK/BufferStream.h>
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#include <AK/BufferStream.h>
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#include <AK/StdLibExtras.h>
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#include <AK/StdLibExtras.h>
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#include <Kernel/FileSystem/Ext2FileSystem.h>
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#include <Kernel/FileSystem/Ext2FileSystem.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/FileSystem/ext2_fs.h>
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#include <Kernel/FileSystem/ext2_fs.h>
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#include <Kernel/Process.h>
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#include <Kernel/Process.h>
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#include <Kernel/RTC.h>
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#include <Kernel/RTC.h>
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@ -90,7 +91,6 @@ bool Ext2FS::initialize()
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kprintf("ext2fs: desc size = %u\n", EXT2_DESC_SIZE(&super_block));
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kprintf("ext2fs: desc size = %u\n", EXT2_DESC_SIZE(&super_block));
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#endif
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#endif
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set_block_size(EXT2_BLOCK_SIZE(&super_block));
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set_block_size(EXT2_BLOCK_SIZE(&super_block));
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ASSERT(block_size() <= (int)max_block_size);
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ASSERT(block_size() <= (int)max_block_size);
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@ -610,7 +610,7 @@ RefPtr<Inode> Ext2FS::get_inode(InodeIdentifier inode) const
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return new_inode;
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return new_inode;
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}
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}
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ssize_t Ext2FSInode::read_bytes(off_t offset, ssize_t count, u8* buffer, FileDescription*) const
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ssize_t Ext2FSInode::read_bytes(off_t offset, ssize_t count, u8* buffer, FileDescription* description) const
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{
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{
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Locker inode_locker(m_lock);
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Locker inode_locker(m_lock);
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ASSERT(offset >= 0);
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ASSERT(offset >= 0);
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@ -656,7 +656,7 @@ ssize_t Ext2FSInode::read_bytes(off_t offset, ssize_t count, u8* buffer, FileDes
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u8 block[max_block_size];
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u8 block[max_block_size];
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for (int bi = first_block_logical_index; remaining_count && bi <= last_block_logical_index; ++bi) {
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for (int bi = first_block_logical_index; remaining_count && bi <= last_block_logical_index; ++bi) {
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bool success = fs().read_block(m_block_list[bi], block);
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bool success = fs().read_block(m_block_list[bi], block, description);
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if (!success) {
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if (!success) {
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kprintf("ext2fs: read_bytes: read_block(%u) failed (lbi: %u)\n", m_block_list[bi], bi);
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kprintf("ext2fs: read_bytes: read_block(%u) failed (lbi: %u)\n", m_block_list[bi], bi);
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return -EIO;
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return -EIO;
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@ -694,7 +694,6 @@ KResult Ext2FSInode::resize(u64 new_size)
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return KResult(-ENOSPC);
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return KResult(-ENOSPC);
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}
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}
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auto block_list = fs().block_list_for_inode(m_raw_inode);
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auto block_list = fs().block_list_for_inode(m_raw_inode);
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if (blocks_needed_after > blocks_needed_before) {
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if (blocks_needed_after > blocks_needed_before) {
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auto new_blocks = fs().allocate_blocks(fs().group_index_from_inode(index()), blocks_needed_after - blocks_needed_before);
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auto new_blocks = fs().allocate_blocks(fs().group_index_from_inode(index()), blocks_needed_after - blocks_needed_before);
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return KSuccess;
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return KSuccess;
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}
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}
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ssize_t Ext2FSInode::write_bytes(off_t offset, ssize_t count, const u8* data, FileDescription*)
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ssize_t Ext2FSInode::write_bytes(off_t offset, ssize_t count, const u8* data, FileDescription* description)
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{
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{
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ASSERT(offset >= 0);
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ASSERT(offset >= 0);
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ASSERT(count >= 0);
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ASSERT(count >= 0);
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ByteBuffer block;
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ByteBuffer block;
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if (offset_into_block != 0 || num_bytes_to_copy != block_size) {
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if (offset_into_block != 0 || num_bytes_to_copy != block_size) {
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block = ByteBuffer::create_uninitialized(block_size);
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block = ByteBuffer::create_uninitialized(block_size);
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bool success = fs().read_block(m_block_list[bi], block.data());
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bool success = fs().read_block(m_block_list[bi], block.data(), description);
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if (!success) {
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if (!success) {
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kprintf("Ext2FSInode::write_bytes: read_block(%u) failed (lbi: %u)\n", m_block_list[bi], bi);
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kprintf("Ext2FSInode::write_bytes: read_block(%u) failed (lbi: %u)\n", m_block_list[bi], bi);
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return -EIO;
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return -EIO;
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#ifdef EXT2_DEBUG
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#ifdef EXT2_DEBUG
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dbgprintf("Ext2FSInode::write_bytes: writing block %u (offset_into_block: %u)\n", m_block_list[bi], offset_into_block);
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dbgprintf("Ext2FSInode::write_bytes: writing block %u (offset_into_block: %u)\n", m_block_list[bi], offset_into_block);
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#endif
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#endif
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bool success = fs().write_block(m_block_list[bi], block.data());
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bool success = fs().write_block(m_block_list[bi], block.data(), description);
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if (!success) {
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if (!success) {
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kprintf("Ext2FSInode::write_bytes: write_block(%u) failed (lbi: %u)\n", m_block_list[bi], bi);
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kprintf("Ext2FSInode::write_bytes: write_block(%u) failed (lbi: %u)\n", m_block_list[bi], bi);
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ASSERT_NOT_REACHED();
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ASSERT_NOT_REACHED();
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{
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{
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m_is_blocking = !(flags & O_NONBLOCK);
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m_is_blocking = !(flags & O_NONBLOCK);
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m_should_append = flags & O_APPEND;
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m_should_append = flags & O_APPEND;
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m_direct = flags & O_DIRECT;
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m_file_flags = flags;
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m_file_flags = flags;
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}
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}
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String absolute_path() const;
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String absolute_path() const;
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bool is_direct() const { return m_direct; }
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bool is_directory() const { return m_is_directory; }
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bool is_directory() const { return m_is_directory; }
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File& file() { return *m_file; }
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File& file() { return *m_file; }
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bool m_is_blocking { true };
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bool m_is_blocking { true };
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bool m_is_directory { false };
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bool m_is_directory { false };
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bool m_should_append { false };
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bool m_should_append { false };
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bool m_direct { false };
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FIFO::Direction m_fifo_direction { FIFO::Direction::Neither };
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FIFO::Direction m_fifo_direction { FIFO::Direction::Neither };
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};
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};
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#define O_DIRECTORY 00200000
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#define O_DIRECTORY 00200000
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#define O_NOFOLLOW 00400000
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#define O_NOFOLLOW 00400000
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#define O_CLOEXEC 02000000
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#define O_CLOEXEC 02000000
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#define O_DIRECT 04000000
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#define O_NOFOLLOW_NOERROR 0x4000000
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#define O_NOFOLLOW_NOERROR 0x4000000
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class Custody;
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class Custody;
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#define O_DIRECTORY 00200000
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#define O_DIRECTORY 00200000
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#define O_NOFOLLOW 00400000
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#define O_NOFOLLOW 00400000
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#define O_CLOEXEC 02000000
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#define O_CLOEXEC 02000000
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#define O_DIRECT 04000000
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#define S_IFMT 0170000
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#define S_IFMT 0170000
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#define S_IFDIR 0040000
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#define S_IFDIR 0040000
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