mkfs.btrfs --rootdir provides user a method to generate btrfs with pre-written content while without the need of root privilege.
However the code is quite old and doesn't get much review or test. This makes some strange behavior, from customized chunk allocation (which uses the reserved 0~1M device space) to lack of special file handler (Fixed in previous 2 patches). The reworked --rootdir will be based on traditional mkfs, everything is processed after traditional mkfs, so nothing is customized. The result will be an equivalent of mkfs, mount, cp, umount. (If btrfs-progs chunk/extent allocator acts as the same as kernel) And, add extra explanation for --rootdir, since the old implement introduced a confusing behavior to limit the filesystem size. The 1st patch fixes a bug that causes any write after cleanup_temp_chunks() to trigger a NULL pointer dereference. The 2nd patch changes the work flow of --rootdir, and slightly changed the behavior, which will not shrink filesystem size by its own. The 3rd patch will shrink the fs, to keep the behavior the same as old --rootdir. If anyone doesn't like the behavior, it can be removed easily. (Which is the main part of the new code, I'd like to get rid of this) The 4th patch enhance the verbose output to reflect the real chunk allocation of --rootdir. The final patch add extra documentary explanation. Qu Wenruo (5): btrfs-progs: Fix one-byte overlap bug in free_block_group_cache btrfs-progs: mkfs: Rework rootdir option to avoid custom chunk layout btrfs-progs: mkfs: Shrink the image for rootdir to minimal size btrfs-progs: mkfs: Update allocation info before verbose output btrfs-progs: Doc/mkfs: Add explanation for rootdir parameter Documentation/mkfs.btrfs.asciidoc | 3 + extent-tree.c | 2 +- mkfs/main.c | 342 ++++++++++++++++++-------------------- 3 files changed, 164 insertions(+), 183 deletions(-) -- 2.14.1 -- 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
