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[FREELDR] Use less memory when doing unaligned reads on Btrfs

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Mark Harmstone 2019-10-11 00:32:14 +01:00 committed by Victor Perevertkin
parent 90c5cac72c
commit 77e2dc42a0
1 changed files with 21 additions and 7 deletions
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28
boot/freeldr/freeldr/lib/fs/btrfs.c
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@ -704,20 +704,34 @@ static u64 btrfs_read_extent_reg(struct btrfs_path *path, struct btrfs_file_exte
if (extent->compression == BTRFS_COMPRESS_NONE)
{
physical += extent->offset + offset;
if (physical & (512 - 1))
{
/* If somebody tried to do unaligned access */
physical -= offset;
temp_out = FrLdrTempAlloc(size + offset, TAG_BTRFS_FILE);
if (!disk_read(physical, temp_out, size + offset))
/* If somebody tried to do unaligned access */
if (physical & (SECTOR_SIZE - 1))
{
u32 shift;
temp_out = FrLdrTempAlloc(SECTOR_SIZE, TAG_BTRFS_FILE);
if (!disk_read(ALIGN_DOWN_BY(physical, SECTOR_SIZE), temp_out, SECTOR_SIZE))
{
FrLdrTempFree(temp_out, TAG_BTRFS_FILE);
return READ_ERROR;
}
memcpy(out, temp_out + offset, size);
shift = (u32)(physical & (SECTOR_SIZE - 1));
if (size <= SECTOR_SIZE - shift)
{
memcpy(out, temp_out + shift, size);
FrLdrTempFree(temp_out, TAG_BTRFS_FILE);
return size;
}
memcpy(out, temp_out + shift, SECTOR_SIZE - shift);
FrLdrTempFree(temp_out, TAG_BTRFS_FILE);
if (!disk_read(physical + SECTOR_SIZE - shift, out + SECTOR_SIZE - shift, size - SECTOR_SIZE + shift))
return READ_ERROR;
} else
{
if (!disk_read(physical, out, size))