On 07/25/2012 06:41 PM, Guenther Rasch wrote: > Hi! > > I'm writing my bsc thesis about btrfs and I'm analyzing the > btrfs metadata structure at the moment. > > I'm using fedora 17 with kernel 3.4 and btrfs-prog from your > git-repository. For an overview I use "btrfs-debug-tree" and > here are my questions: > > The root tree contains some inode_items, but I don't understand > the meaning of them: > item 4 key (ROOT_TREE_DIR INODE_ITEM 0) itemoff 3101 itemsize 160 > inode generation 3 size 0 block group 0 mode 40555 links 1 > > item 5 key (ROOT_TREE_DIR INODE_REF 6) itemoff 3089 itemsize 12 > inode ref index 0 namelen 2 name: .. > > The key for an inode_item is objectid=ROOT_TREE_DIR. ROOT-TREE-DIR is > the inode-Nr.? > What does offset=6 regarding INODE_REF mean? --> item 5 > I think you can find the answer by doing grep ROOT_TREE_DIR in btrfs-progs source code. ;) > Also placed in the root tree, I've found entries of > (FREE_SPACE UNTYPED ....) > What does UNTYPED mean in this context and the offset is > the logical address of a block group (I guess...)? This > item has a pointer to an inode_item, is that right? > It's free space cache, which refers to free-space-cache.c in upstream's code. > And last question about this entries: > item 2 key (FS_TREE INODE_REF 6) itemoff 3500 itemsize 17 > inode ref index 0 namelen 7 name: default > ... > item 6 key (ROOT_TREE_DIR DIR_ITEM 2378154706) itemoff 3052 itemsize 37 > location key (FS_TREE ROOT_ITEM 18446744073709551615) type 2 > namelen 7 datalen 0 name: default > > There is an INODE_REF (again, offset 6...?) pointing to > which inode? I cannot find some... > What's about that offset in location key (FS_TREE....) > > Thx in advance for your patience and answers! > > Regards > Guenther > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
