Hi, On Sun, Feb 21, 2016 at 6:27 AM, Richard Weinberger <richard.weinberger@xxxxxxxxx> wrote: > Cc'ing linux-mtd. > > On Sat, Feb 20, 2016 at 1:02 AM, Pushpal Sidhu <psidhu@xxxxxxxxxxxxx> wrote: >> It seems that overlayfs requires RENAME_WHITEOUT and RENAME_EXCHANGE. >> However, these two flags aren't currently supported in ubifs (or >> anything other than ext4, f2fs, and xfs). This causes any atomic >> renames to fail (e.g. using 'mv' command). > > Hmm, right. I always thought overlayfs does checks at mount time. > But apparently I was wrong. > Thanks for pointing this out. No problem. >> I'm currently trying to implement these flags, but I'm having some >> issues as I'm pretty vanilla when it comes to implementation details >> on ubifs. I'm taking inspiration from patches [1] and [2], but I'm >> kind of coming up short. Is there anyone currently working on this? If >> not, I would certainly appreciate any advice for implementing these >> features. > > Not to my knowledge. But you can use my O_TMPFILE patch as start. > See linux-mtd mailinglist. > If you have questions, just ask. > As using overlayfs is common on embedded stuff we definitely need that on UBIFS. > Just in case I'm putting that also on my todo list. Great, that patch looks like it would help. If I can't totally figure out a solution on my own, I'll let you know since you can probably type out the implementation to these flags much faster than I am currently able to. >> What I'm doing: I'm attempting to create a 'whiteout' object from >> within the ubifs_rename function. However, I noticed that it calls >> ubifs_jnl_rename, which is where I believe I should try to implement >> this. I haven't touched RENAME_EXCHANGE yet. >> >> [1] https://dev.openwrt.org/browser/trunk/target/linux/generic/patches-4.4/110-jffs2-use-.rename2-and-add-RENAME_WHITEOUT-support.patch >> [2] https://dev.openwrt.org/browser/trunk/target/linux/generic/patches-4.4/111-jffs2-add-RENAME_EXCHANGE-support.patch > > Hmm, these patches seem wrong to me. > Unless I'm very mistaken it looks like every whiteout creates an busy > orphaned inode. Great, I will only look at implementations currently in the kernel then. Thanks, - Pushpal > -- > Thanks, > //richard -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
