On 01/04/17 00:21, David Sterba wrote:
On Wed, Dec 21, 2016 at 03:42:07PM +0800, Anand Jain wrote:
Both BTRFS_IOC_DEFRAG and BTRFS_IOC_DEFRAG_RANGE call the same
function- btrfs_ioctl_defrag(), however BTRFS_IOC_DEFRAG does
not support any argument, so check that and return not supported
if provided. This has valid impact at the user end, in the cli below
btrfs filesystem defrag -clzo /btrfs
the -c option (or similarly other) is only applicable to the file
defrag, which is either provided in the argument or when used along
with the -r option, however as of now the above cli does not report
any error. This patch will fix it.
I think it would be better to do the sanitization on the userspace side.
>
In this case combination of a compression option and bare directory
would not lead to the expected result.
Hmm.. I am confused on the expected result here, what should it be ?
My thinking, compression option on the directory is not supported.
That's because the kernel calls btrfs_defrag_root() for dir as arg,
which does not accept any option.
In the same context if either -r option is used (then it picks up
individual files as arg) or if a file is used as arg, then kernel
calls btrfs_defrag_files() which then the options makes sense.
IMO it's deciding between
"pass any arguments to kernel" - here returning EOPNOTSUPP would be
quite unclear what went wrong
vs.
"validate as much arguments as we can before passing to kernel" - and
we'll know early that the combination is not valid, also that we want
to deprecate it etc.
btrfs-progs is one of the tool. If API is tested with a test program
it will still can be shown as failing.
The kernel problem statement is:
- ioctl("/dir", BTRFS_IOC_DEFRAG, options)
- ioctl("/dir", BTRFS_IOC_DEFRAG_RANGE, options)
the above ioctl usage provides false impression that options have
worked, but the kernel does not use the options at all.
Its a different story if btrfs_defrag_root() would support options
in the long term ?
I vote for #2 as we have enough information to give an informative error
message.
Thanks, Anand
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