This line may do come form linux kernel, As you can see in the first link I refers says this number (1UL << 15) is kind of magic number. If you write somethimg linux standanrded, It is hard to keep abosultely no any linux involued I think even freebsd has some code from linux, like the second link I posted, the freebsd's ext4_ext_get_actual_len and EXT_INIT_MAX_LEN are exactly the same as linux
It is ok if it's considering as not mergeable, I think it is also good just as a reference on the mailinng list, to those people who need to read very large files The debug/fix process, I described here on the first, I use vbox's ext4 uefi driver to read large files, but failed on verfication use some tools I writed, I share it here md5sum.efi: https://1drv.ms/u/s!As-Ec5SPH0fuillwxhIsePY0KBla?e=WzHaBf diff.efi: https://1drv.ms/u/s!As-Ec5SPH0fuilgMwlg6yNQOFCD1?e=GVoKuH then I googed to for replacement(on the first, I dont plat to fixed it myself), But no luck, the all fails on large file read verfication. But I noticed the performance of edk2-platforms's ext4 driver is most best of all those uefi ext4 drivers I did not found a working one, so I need to fix it. First I did some guess and research, and then I added some logs dump the edk2's read extents to serial on data that did't not match, (the diff.efi tool I write will stop reading when data dismatch) I compare those log dump to linux's 'filefrag -v"'s ouput, It is easy to found the difference, then I google to find the logic about unwritten extents, then did the fix From: Pedro Falcato <pedro.falc...@gmail.com> Sent: Thursday, October 28, 2021 5:34 To: QiZhou <atm...@outlook.com> Cc: devel@edk2.groups.io <devel@edk2.groups.io> Subject: Re: [PATCH][Ext4Pkg] unwritten extent suuport Hi Qi, If you didn't use the Linux kernel (nor the documentation) as a reference, can you please tell me what you've used? I'm asking because there's at least a line that's suspiciously similar to Linux's code: #define EXTENT_INIT_MAX_LEN (1UL << 15) the UL looks redundant to me, since there's no need for it. Also, I prefer that you fix the typos yourself and format the patch correctly, including the code. On Wed, Oct 27, 2021 at 4:45 PM QiZhou <atm...@outlook.com> wrote: 1. I am not familiar with freebsd, and don know if freebsd get the same issue, But I do found the freebsd has some code snippets related to unwritten extent, see: https://github.com/freebsd/freebsd-src/blob/b3f46656393f5c8a6e8305afeb5e8c3638025c26/sys/fs/ext2fs/ext2_extents.h#L37 https://github.com/freebsd/freebsd-src/blob/b3f46656393f5c8a6e8305afeb5e8c3638025c26/sys/fs/ext2fs/ext2_extents.c#L1347 Is Ext4 is freebsd's default/major file system ? 2. I did't look at linux kernel(ext4) berfor send this patch, I cant found any offcial document, so I refer to linux source as a standand when send this patch 3. Yes, unwritten extents are wild used, usally when a file cotains many zeros, or mark file holes(fallocate, qemu-img...) You can generate a file contains a lot of unwritten extents by qemu, for example: qemu-img convert -f raw -O qcow2 win10.img win10.qcow2 # win10.img's size: 10G But for files do not have any continuous zeros, like compressed files, then there will be no any unwritten extents unwritten extents are usally seen in very large files 4. You can fix the typos, My English is not so good On Oct 27 2021, at 10:56 pm, Pedro Falcato <pedro.falc...@gmail.com> wrote: > Hi, > > The patch looks OK despite the typos and lack of proper formatting on > the commit message. > > But honestly, I don't know if this patch is even mergeable considering > you looked at the Linux kernel's source code for this. The patch was > already trivial enough > if you looked at the documentation and the FreeBSD driver (as I had > done in the past but never got to fixing this considering I don't even > know if unwritten extents can appear in the wild). > > I *cannot* stress this enough: Ext4Pkg is a clean room implementation > of ext4 licensed under the BSD-2-Clause-Patent license (which is NOT > compatible with GPLv2) and cannot have random Linux kernel > bits, or any other incompatibly-licensed project's bits for that matter. > > Best regards, > Pedro > > >> On Wed, Oct 27, 2021 at 2:37 PM qi zhou <atm...@outlook.com> wrote: >> >>> From: "Qi Zhou" <atm...@outlook.com> >>> Subject: [PATCH] unwritten extent suuport >>> >>> the real lenght of uninitialized/unwritten extent should be (ee_len >>> - (1UL << 15)), and >>> all related block should been read as zeros. see: >>> https://github.com/torvalds/linux/blob/d25f27432f80a800a3592db128254c8140bd71bf/fs/ext4/ext4_extents.h#L156 >>> >>> Signed-off-by: Qi Zhou <atm...@outlook.com> >>> --- >>> Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h | 5 +++++ >>> Features/Ext4Pkg/Ext4Dxe/Extents.c | 4 ++-- >>> Features/Ext4Pkg/Ext4Dxe/Inode.c | 5 +++++ >>> 3 files changed, 12 insertions(+), 2 deletions(-) >>> >>> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h >>> b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h >>> index 070eb5a..7ca8eee 100644 >>> --- a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h >>> +++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h >>> @@ -402,6 +402,11 @@ typedef struct { >>> >>> #define EXT4_MIN_DIR_ENTRY_LEN 8 >>> >>> +#define EXTENT_INIT_MAX_LEN (1UL << 15) >>> + >>> +#define EXTENT_REAL_LEN(x) ((UINT16)(x <= EXTENT_INIT_MAX_LEN ? x : >>> (x - EXTENT_INIT_MAX_LEN))) >>> +#define EXTENT_IS_UNWRITTEN(x) (x > EXTENT_INIT_MAX_LEN) >>> + >>> // This on-disk structure is present at the bottom of the extent tree >>> typedef struct { >>> // First logical block >>> diff --git a/Features/Ext4Pkg/Ext4Dxe/Extents.c >>> b/Features/Ext4Pkg/Ext4Dxe/Extents.c >>> index 5fa2fe0..21af573 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 + >>> EXTENT_REAL_LEN(Ext->ee_len) > 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 + >>> EXTENT_REAL_LEN(Extent->ee_len)) { >>> return 0; >>> } >>> >>> diff --git a/Features/Ext4Pkg/Ext4Dxe/Inode.c >>> b/Features/Ext4Pkg/Ext4Dxe/Inode.c >>> index 63cecec..d691ec7 100644 >>> --- a/Features/Ext4Pkg/Ext4Dxe/Inode.c >>> +++ b/Features/Ext4Pkg/Ext4Dxe/Inode.c >>> @@ -151,6 +151,11 @@ Ext4Read ( >>> // Potential improvement: In the future, we could get the >>> hole's tota >>> // size and memset all that >>> SetMem (Buffer, WasRead, 0); >>> + } else if(EXTENT_IS_UNWRITTEN(Extent.ee_len)) { >>> + HoleOff = CurrentSeek - (UINT64)Extent.ee_block * >>> Partition->BlockSize; >>> + HoleLen = EXTENT_REAL_LEN(Extent.ee_len) * >>> Partition->BlockSize - HoleOff; >>> + WasRead = HoleLen > RemainingRead ? RemainingRead : HoleLen; >>> + SetMem (Buffer, WasRead, 0); >>> } else { >>> ExtentStartBytes = MultU64x32 ( >>> LShiftU64 (Extent.ee_start_hi, 32) | >>> -- >>> 2.17.1 >>> > > > -- > > Pedro Falcato -- Pedro Falcato -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#82762): https://edk2.groups.io/g/devel/message/82762 Mute This Topic: https://groups.io/mt/86629612/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-