06.06.2011 21:13, Michael Tokarev wrote: > Thank you for the answer. I thought noone will reply... ;) > > 06.06.2011 07:39, Ted Ts'o wrote: >> On Sun, May 29, 2011 at 08:08:55PM +0400, Michael Tokarev wrote: >>> Hello. >>> >>> Just noticed that at least on ext4, unlinking a >>> non-existing file from a read-only filesystem >>> results in EROFS instead of ENOENT. I'd expect >>> it return ENOENT - it is more logical, at least >>> in my opinion. >>> >>> For one, (readonly) NFS mount returns ENOENT in >>> this case. >> >> Um, it doesn't for me. Testing on v3.0-rc1: >> >> # ls /test/foo; rm /test/foo >> ls: cannot access /test/foo: No such file or directory >> rm: cannot remove `/test/foo': No such file or directory > > This is a hack in coreutils rm to work around this > kernel change. The comment at > http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/remove.c#n450 > says: > > /* The unlinkat from kernels like linux-2.6.32 reports EROFS even for > nonexistent files. When the file is indeed missing, map that to ENOENT, > so that rm -f ignores it, as required. Even without -f, this is useful > because it makes rm print the more precise diagnostic. */ > > so that rm(1) calls stat(2) to see if the file actually > exist if unlinkat() returned EROFS, and turns this errno > into ENOENT. And another followup to this, -- the original case when I actually noticed the problem. A readonly-mounted root filesystem with /etc in git (the repository is in /var, symlinked from /etc/.git). I deleted a few files from /etc (when it was readwrite), and noticed that I forgot to commit the change. So I used `git rm oldfiles' and voila, git, for the first time, refused to commit stuff for me in this configuration, -- before, I was always able to _commit_ the changes even if the working tree is read-only. It works for everything but not for unlinks. > That is, rm(1) output is not a good indicator. Use > > strace rm -f /test/foo 2>&1 | grep unlink > > to see the actual errno reported by the kernel. > > Here's the POSIX description of unlink (and unlinkat) again: > http://pubs.opengroup.org/onlinepubs/009695399/functions/unlink.html > > Thanks! > > /mjt > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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
