On 09/06/2017 08:02 PM, Austin S. Hemmelgarn wrote: > On 2017-09-06 13:48, Goffredo Baroncelli wrote: >> On 09/06/2017 07:16 PM, Austin S. Hemmelgarn wrote: [...] >>>> Sorry but I don't understand. If you reach the step a3; you have: >>>> - the final disk, and an environment fully working. So I am still inclined >>>> to think that using "mkfs.btrfs --root-dir" is more complicated in *this >>>> case*. >>> With the current released code (without these patches), `-r` can be used to >>> generate a filesystem image that has zero free space. In that case, step >>> a3 does not give you a fully working environment, >> >> True, this doesn't *give* you a filly working environment, _but_ you perform >> the step a3 in a "fully working environment", an you have at hand the target >> disk.. > You could just as easily be booted into a minimalistic install environment, > and if you netbooted that, then it's pretty likely that you want it as small > as possible, and not needing tar or btrfs-progs for the actual install will > save a lot of space (multiple MB doesn't sound like much, but when you're > dealing with a tiny system to begin with, it can be very significant).
Step a3 need to have access to the raw disk image build at step1; this is quite incompatible with a "minimalistic install environment"; and even if you have access it via net, in the same way you can have access to a fully working environment.... [...] >>>>>> >>>>>> where <file-to-be-created> doesn't have to exists before mkfs.btrfs, and >>>>>> after >>>>>> a) <file-to-be-created> contains the image >>>>>> b) <file-to-be-created> is the smallest possible size. >>>>>> >>>>>> Definitely I don't like the truncate done by the operator by hand after >>>>>> the mkfs.btrfs (current behavior). >>>>> FWIW, the current release behavior doesn't require the truncate, and >>>>> properly generates the file for the filesystem. >>>> If you don't do truncate, you have the fully partition... Or there is >>>> something that I miss ? >>> The current release, without these patches, run using a non-existent file >>> and the `-r` option, will produce a filesystem image of the exact size >>> needed to hold everything in the directory passed to `-r`. It doesn't >>> require truncation unless used on a file that already exists. >> >> Of course the truncate is not needed, because you are using a sparse file. >> But if you use a sparse file..... it is not even needed the shrinking! >> Because the file will consume the same space on the disk ! > Unless you want to use the file elsewhere. It's a pretty rare occurrence > outside of testing that you generate a filesystem image and use it as-is > without transferring it somewhere (usually onto an actual storage device). > Once you're talking about moving it, whether or not the file itself is sparse > usually doesn't matter, especially if the file is leaving the local system by > some means other than NFS or rsync. ???? If you don't truncate you have the full-image in any case.... > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
