WIP: libcontainer/specconv/spec_linux: defaults should not be a no-op #1444
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It has been since it landed in 9fac183 (Initial commit of runc binary, 2015-06-21), but the spec currently references mount(8) for these options [1] and mount(8) has: defaults Use the default options: rw, suid, dev, exec, auto, nouser, and async. Note that the real set of all default mount options depends on kernel and filesystem type. See the beginning of this section for more details. I exepect that "real set" paragraph applies to: Note that filesystems also have per-filesystem specific default mount options (see for example tune2fs -l output for extN filesystems). This commit sets up 'defaults' according to that option list, but does not do anything about 'auto' or 'nouser', which do not map to MS_* flags and only apply to fstab entries. For what its worth, util-linux 2.28.2 seems to ignore 'defaults' instead of clearing bits: # strace -o /tmp/trace mount -t tmpfs -o ro,defaults - /tmp/a # grep 'mount(' /tmp/trace mount("-", "/tmp/a", "tmpfs", MS_MGC_VAL|MS_RDONLY, NULL) = 0 While a single-bit clear option does unset an earlier bit: # strace -o /tmp/trace mount -t tmpfs -o ro,rw - /tmp/a # grep 'mount(' /tmp/trace mount("-", "/tmp/a", "tmpfs", MS_MGC_VAL, NULL) = 0 but the spec is currnently punting to the util-linux mount(8) page and not to the util-linux implementation. [1]: https://github.com/opencontainers/runtime-spec/blame/v1.0.0-rc5/config.md#L68 [2]: http://man7.org/linux/man-pages/man8/mount.8.html#FILESYSTEM-INDEPENDENT_MOUNT%20OPTIONS Signed-off-by: W. Trevor King <[email protected]>
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I've posted a request for clarification to the util-linux list to resolve the differences between my reading of the man page and the util-linux implementation. |
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Updated mount(8) wording is still up in the air, but Karel Zak confirmed that runC's current |
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It has been since it landed in 9fac183, but the spec currently references mount(8) for these options and mount(8) has:
I exepect that “real set” paragraph applies to:
For what its worth, util-linux 2.28.2 seems to ignore
defaultsinstead of clearing bits:While a single-bit clear option does unset an earlier bit:
but the spec is currnently punting to the util-linux mount(8) page and not to the util-linux implementation.
Related to opencontainers/runtime-spec#771.