[edk2-devel] [edk2-platforms PATCH] Ext4Pkg: Add uninitialized extents support
Pedro Falcato
pedro.falcato at gmail.com
Thu Nov 18 20:31:02 UTC 2021
It's been over two weeks and a quick Rb would be great, since this patch is
relatively trivial and it would fix a bug. Again, if I'm doing anything
wrong, please let me know.
Thanks,
Pedro
On Mon, Nov 1, 2021 at 9:29 PM Pedro Falcato <pedro.falcato at gmail.com>
wrote:
> Quick PS: I CC'd the edk2-platforms stewards on the patch because there's
> no co-maintainer, and from what I gathered, that's what I'm supposed to do.
> If I'm mistaken, please let me know.
>
> Thanks,
> Pedro
>
> On Fri, Oct 29, 2021 at 2:04 AM Pedro Falcato via groups.io
> <pedro.falcato=gmail.com at groups.io> wrote:
>
>> Uninitialized extents are special extents that have blocks allocated,
>> but are specified as uninitialized and therefore, reads behave the
>> same as file holes (reads 0), while writes already have blocks allocated.
>>
>> Cc: Leif Lindholm <leif at nuviainc.com>
>> Cc: Michael D Kinney <michael.d.kinney at intel.com>
>> Signed-off-by: Pedro Falcato <pedro.falcato at gmail.com>
>> ---
>> Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h | 8 ++++++++
>> Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h | 21 +++++++++++++++++++++
>> Features/Ext4Pkg/Ext4Dxe/Extents.c | 24 ++++++++++++++++++++++--
>> Features/Ext4Pkg/Ext4Dxe/Inode.c | 14 +++++++++++---
>> 4 files changed, 62 insertions(+), 5 deletions(-)
>>
>> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
>> b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
>> index 070eb5a9c8..756b1bbe10 100644
>> --- a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
>> +++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
>> @@ -448,6 +448,14 @@ typedef struct {
>> UINT32 eb_checksum;
>> } EXT4_EXTENT_TAIL;
>>
>> +/**
>> + * EXT4 has this feature called uninitialized extents:
>> + * An extent has a maximum of 32768 blocks (2^15 or 1 << 15).
>> + * When we find an extent with > 32768 blocks, this extent is called
>> uninitialized.
>> + * Long story short, it's an extent that behaves as a file hole but has
>> blocks already allocated.
>> + */
>> +#define EXT4_EXTENT_MAX_INITIALIZED (1 << 15)
>> +
>> typedef UINT64 EXT4_BLOCK_NR;
>> typedef UINT32 EXT4_INO_NR;
>>
>> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
>> b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
>> index a9b932ed52..1d9a4ac6ba 100644
>> --- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
>> +++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
>> @@ -1131,4 +1131,25 @@ Ext4SuperblockCheckMagic (
>> IN EFI_BLOCK_IO_PROTOCOL *BlockIo
>> );
>>
>> +/**
>> + Check if the extent is uninitialized
>> +
>> + @param[in] Extent Pointer to the EXT4_EXTENT
>> +
>> + @returns True if uninitialized, else false.
>> +**/
>> +#define EXT4_EXTENT_IS_UNINITIALIZED(Extent) ((Extent)->ee_len >
>> EXT4_EXTENT_MAX_INITIALIZED)
>> +
>> +/**
>> + Retrieves the extent's length, dealing with uninitialized extents in
>> the process.
>> +
>> + @param[in] Extent Pointer to the EXT4_EXTENT
>> +
>> + @returns Extent's length, in filesystem blocks.
>> +**/
>> +EXT4_BLOCK_NR
>> +Ext4GetExtentLength (
>> + IN CONST EXT4_EXTENT *Extent
>> + );
>> +
>> #endif
>> diff --git a/Features/Ext4Pkg/Ext4Dxe/Extents.c
>> b/Features/Ext4Pkg/Ext4Dxe/Extents.c
>> index 5fa2fe098d..1ae175f417 100644
>> --- a/Features/Ext4Pkg/Ext4Dxe/Extents.c
>> +++ b/Features/Ext4Pkg/Ext4Dxe/Extents.c
>> @@ -332,7 +332,7 @@ Ext4GetExtent (
>> return EFI_NO_MAPPING;
>> }
>>
>> - if (!(LogicalBlock >= Ext->ee_block && Ext->ee_block + Ext->ee_len >
>> LogicalBlock)) {
>> + if (!(LogicalBlock >= Ext->ee_block && Ext->ee_block +
>> Ext4GetExtentLength (Ext) > LogicalBlock)) {
>> // This extent does not cover the block
>> if (Buffer != NULL) {
>> FreePool (Buffer);
>> @@ -413,7 +413,7 @@ Ext4ExtentsMapKeyCompare (
>> Extent = UserStruct;
>> Block = (UINT32)(UINTN)StandaloneKey;
>>
>> - if (Block >= Extent->ee_block && Block < Extent->ee_block +
>> Extent->ee_len) {
>> + if (Block >= Extent->ee_block && Block < Extent->ee_block +
>> Ext4GetExtentLength (Extent)) {
>> return 0;
>> }
>>
>> @@ -593,3 +593,23 @@ Ext4CheckExtentChecksum (
>>
>> return Tail->eb_checksum == Ext4CalculateExtentChecksum (ExtHeader,
>> File);
>> }
>> +
>> +/**
>> + Retrieves the extent's length, dealing with uninitialized extents in
>> the process.
>> +
>> + @param[in] Extent Pointer to the EXT4_EXTENT
>> +
>> + @returns Extent's length, in filesystem blocks.
>> +**/
>> +EXT4_BLOCK_NR
>> +Ext4GetExtentLength (
>> + IN CONST EXT4_EXTENT *Extent
>> + )
>> +{
>> + // If it's an unintialized extent, the true length is ee_len - 2^15
>> + if (EXT4_EXTENT_IS_UNINITIALIZED (Extent)) {
>> + return Extent->ee_len - EXT4_EXTENT_MAX_INITIALIZED;
>> + }
>> +
>> + return Extent->ee_len;
>> +}
>> diff --git a/Features/Ext4Pkg/Ext4Dxe/Inode.c
>> b/Features/Ext4Pkg/Ext4Dxe/Inode.c
>> index 63cecec1f7..48bfe026a3 100644
>> --- a/Features/Ext4Pkg/Ext4Dxe/Inode.c
>> +++ b/Features/Ext4Pkg/Ext4Dxe/Inode.c
>> @@ -144,11 +144,19 @@ Ext4Read (
>>
>> HasBackingExtent = Status != EFI_NO_MAPPING;
>>
>> - if (!HasBackingExtent) {
>> + if (!HasBackingExtent || EXT4_EXTENT_IS_UNINITIALIZED (&Extent)) {
>> +
>> HoleOff = BlockOff;
>> - HoleLen = Partition->BlockSize - HoleOff;
>> +
>> + if (!HasBackingExtent) {
>> + HoleLen = Partition->BlockSize - HoleOff;
>> + } else {
>> + // Uninitialized extents behave exactly the same as file holes.
>> + HoleLen = Ext4GetExtentLength (&Extent) - HoleOff;
>> + }
>> +
>> WasRead = HoleLen > RemainingRead ? RemainingRead : HoleLen;
>> - // Potential improvement: In the future, we could get the hole's
>> tota
>> + // Potential improvement: In the future, we could get the file
>> hole's total
>> // size and memset all that
>> SetMem (Buffer, WasRead, 0);
>> } else {
>> --
>> 2.33.1.windows.1
>>
>>
>>
>> ------------
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>> pedro.falcato at gmail.com]
>> ------------
>>
>>
>>
>
> --
> Pedro Falcato
>
--
Pedro Falcato
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