From: Gao Xiang <email@example.com> To: Yue Hu <firstname.lastname@example.org> Cc: email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: Re: [PATCH] erofs-utils: do not check ->idata_size for compressed files in erofs_prepare_inode_buffer() Date: Tue, 31 Aug 2021 19:15:50 +0800 [thread overview] Message-ID: <YS4PZvVbdHGqurAD@B-P7TQMD6M-0146.local> (raw) In-Reply-To: <email@example.com> Hi Yue, On Tue, Aug 31, 2021 at 05:00:29PM +0800, Yue Hu wrote: > On Thu, 17 Jun 2021 18:14:17 +0800 > Yue Hu <firstname.lastname@example.org> wrote: > > > On Thu, 17 Jun 2021 17:30:26 +0800 > > Gao Xiang <email@example.com> wrote: > > > > > On Thu, Jun 17, 2021 at 05:27:33PM +0800, Gao Xiang wrote: > > > > On Thu, Jun 17, 2021 at 05:15:55PM +0800, Yue Hu wrote: > > > > > On Thu, 17 Jun 2021 17:04:29 +0800 > > > > > Gao Xiang <firstname.lastname@example.org> wrote: > > > > > > > > > > > Hi Yue, > > > > > > > > > > > > On Thu, Jun 17, 2021 at 04:29:54PM +0800, Yue Hu wrote: > > > > > > > From: Yue Hu <email@example.com> > > > > > > > > > > > > > > erofs_write_compressed_file() will always set inode->idata_size = 0 > > > > > > > if succeed, that means no tail-end data for compressed files. So, no > > > > > > > need to call erofs_prepare_tail_block() which is used to handle > > > > > > > tail-end data for that case. Just skip it. > > > > > > > > > > > > Thanks for the patch, due to somewhat long time so I don't quite > > > > > > remember the exact logic here now... > > > > > > > > > > > > Yet from the description before, it's not strictly correct > > > > > > since my original intention would be to support tail-packing > > > > > > inline compressed data which is similar to uncompressed case > > > > > > to decrease tail extent I/O and save more space. > > > > > > > > > > nice. > > > > > > > > > > > > > > > > > BTW, if you have some interest, would you like to implement it? :) > > > > > > > > > > I don't know if i can finish it. But i would like to have a try :) > > > > > > > > My rough thought is to try to inline the last tail compresseed > > > > extent after the on-disk compressed extents, maybe we could let > > > > it work for non-compact (legacy) compress index format cases... > > > > > > I mean try to implement non-compact (legacy) compress index format cases > > > first. > > I'm trying to do it under 4.19 code (since i have no 5.x environment temporarily). > > Now, i think mkfs should be done. But, kernel side seems not working fine(no crash, > no decompression warning/bug). Only some files are working, others not. I'm sure i > can catch the inline data correctly via file dump. And I'm trying debug the issue. > Maybe i need more time to read/understand more decompression code related. > > BTW, now i understand no need to go z_erofs_vle_work_xxx for inline part(cur-end) > , just go next_part after mapping as below, am i right? > You are right. For the common cases (except for fiemap or cases to get the exact decompressed length), we only need to calculate the start of the compression extent, so it's transversal in the reverse order. But really... Again, I don't suggest using 4.19 staging code for real production or further development. The uncompressed part is considered as stable, but compression side may not (also it was disabled by default). Please also see, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/staging/erofs/Kconfig?h=v4.19#n86 " config EROFS_FS_ZIP bool "EROFS Data Compresssion Support" depends on EROFS_FS help Currently we support VLE Compression only. Play at your own risk. If you don't want to use compression feature, say N. " Our original first real production codebase was between 5.2~5.3. Therefore, I suggest using >= 5.4 LTS codebase for production. You could also find some backport codebase on github, e.g.: https://github.com/nolange/erofs_kernel_4_19 , which backports 5.6 erofs codebase to 4.19. As for tail-packing inline extent feature, how about focusing on on-disk design and mkfs/erofsfuse implementation first as PoC? I'm afraid that if you only focus on 4.19 codebase, the format of compact indexes will be ignored, but "compact indexes" is the default option for erofs now since it has less metadata overhead than non-compact indexes, so both the sequential / random read are better. Thanks, Gao Xiang > Thanks. > > > > > Ok, let me try to implement it. > > > > Thanks.
next prev parent reply other threads:[~2021-08-31 11:16 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-17 8:29 Yue Hu 2021-06-17 9:04 ` Gao Xiang 2021-06-17 9:15 ` Yue Hu 2021-06-17 9:27 ` Gao Xiang 2021-06-17 9:30 ` Gao Xiang 2021-06-17 10:14 ` Yue Hu 2021-08-31 9:00 ` Yue Hu 2021-08-31 11:15 ` Gao Xiang [this message] 2021-08-31 11:56 ` Yue Hu 2021-08-31 12:20 ` Gao Xiang 2021-09-01 2:20 ` Yue Hu 2021-09-01 3:05 ` Gao Xiang
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=YS4PZvVbdHGqurAD@B-P7TQMD6M-0146.local \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --subject='Re: [PATCH] erofs-utils: do not check ->idata_size for compressed files in erofs_prepare_inode_buffer()' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).