Hi, On Sat, 11 Sep 2010 05:46:29 -0400, Matteo Frigo wrote: > Ryusuke Konishi <ryusuke@xxxxxxxx> writes: > > > An experimental resize feature did exist, but it's not applicable to > > the current version. And, it didn't support shrinking. > > So the feature you want is not available now. (Sorry for inconvenience) > > Ryusuke, > > Thanks for developing nilfs2, it is a superb piece of work. > > I am interested in the resize feature and willing to implement it, but I > need a little help. My understanding of the nilfs2 source code in > 2.6.35.4 is that in order to grow a file system it should be sufficient > to change s_nsegments in both superblocks while the file system is > unmounted. Yes, right. To be precise, you also have to move the secondary superblock, and s_dev_size should be changed, too. Anyway, all that's required for the off-line expansion are these modifications. > If I understand correctly, the sufile grows automatically to > accomodate the additional segments because nilfs_sufile_alloc() calls > nilfs_sufile_get_segment_usage_block() with create=1, which grows the > sufile as necessary. Exactly. > Is this interpretation correct? If so, it should not be too hard to > code a little utility that grows an unmounted file system. (Later we'll > worry about shrinking and online resize.) > > You allude to an experimental resize feature. Do you have code that I > can adapt to the current version? No, the experimental one got completely obsolete. At least, we have no applicable patch after the secondary super block was added. If someone make a new one, I will apply that. Recently, Jiro SEKIBA added library functions to modify super blocks. I think, you can implement "nilfs-resize" by enhancing his work, by amending "nilfs_sb_write" function. The change is available on the latest util's git repo. Thanks, Ryusuke Konishi -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
