losetuping files in tmpfs fails?
Greetings.
Quoted 1 line · Andrew Morton
Yup, tmpfs doesn't provide some of the facilities which the
<snip>
Quoted 2 lines
It's not obvious that there's a burning need to support loop-on-tmpfs though, is there?
No, there isn't. I noticed this myself a few months back, but didn't
complain because, well, the purpose of tmpfs is to provide support for POSIX shared memory, right? (At least according to Configure.help). {If,/ Because} tmpfs does that correctly, it's not broken.
The only app I've encountered that breaks with this is mkinitrd and
associates, but it should at least attempt to fallback to the user's home directory IMHO (without complaining "you're all out of loop devices" - an old Redhat mkinitrd).
Cheerio!
- ioj
Followup to: <[email protected]> By author: Ishan Oshadi Jayawardena <[email protected]> In newsgroup: linux.dev.kernel
Quoted 6 lines
No, there isn't. I noticed this myself a few months back, but didn't
complain because, well, the purpose of tmpfs is to provide support for POSIX shared memory, right? (At least according to Configure.help). {If,/ Because} tmpfs does that correctly, it's not broken.
That was the original reason for it, when it was called "shmfs". It has become more than that, due to the fairly clever observation that "shmfs" already supported virtually everything needed for a swappable temporary-storage general filesystem.
-hpa
P.S. On kernel.org, I was forced to hack tmpfs so that it returns a nonzero size for directories; otherwise "make distclean" breaks for older Linux kernels, and the incdiff robot that runs on kernel.org relies on this operation working correctly. It would be a good thing if tmpfs could account for the amount of memory consumed by directories, etc.
Signature · 3 lines
<[email protected]> at work, <[email protected]> in private! "Unix gives you enough rope to shoot yourself in the foot." http://www.zytor.com/~hpa/puzzle.txt <[email protected]>
tmpfs accounting (was: losetuping files in tmpfs fails?)
In reply to Ishan Oshadi JayawardenaHi Peter,
Quoted 6 lines · H. Peter Anvin
P.S. On kernel.org, I was forced to hack tmpfs so that it returns a nonzero size for directories; otherwise "make distclean" breaks for older Linux kernels, and the incdiff robot that runs on kernel.org relies on this operation working correctly. It would be a good thing if tmpfs could account for the amount of memory consumed by directories, etc.
I would not like to add the real size without a bigger goal (I would not see a problem with a fake size).
On the other side I could imagine that we make the directories tmpfs files which hold the swap vectors of the real tmpfs files of this directory. With this we would gain swappable meta data for tmpfs and had a real size for the directories for free.
Greetings
Christoph
Re: tmpfs accounting (was: losetuping files in tmpfs fails?)
In reply to Ishan Oshadi JayawardenaQuoted 4 lines · Christoph Rohland
I would not like to add the real size without a bigger goal (I would not see a problem with a fake size).
It defeats the filesystem size limit, and makes it possible to an unprivileged user to consume unlimited amounts of kernel memory.
-hpa