On Fri, Nov 09, 2012 at 02:47:41PM +0800, Jeff Liu wrote: > Hello, > > I observed that there is an issue on our official DOC for AG disk > layout, which can be found at: > http://xfs.org/docs/xfsdocs-xml-dev/XFS_Filesystem_Structure//tmp/en-US/html/Allocation_Groups.html > > It shows that the IBT block is followed by the block where AGFL sector > resides. However, it should be followed by the > CNT block according to my debug, like below: > > ------------------------------- > superblock > AG free block info > AG inode B+tree info > AG internal free list > ------------------------------- > Root of free space B+tree > B+tree key is block number > ------------------------------- > Root of free space B+tree > B+tree key is block count > -------------------------------- > Root of inodes B+tree > -------------------------------- > > Maybe the DOC is old, or am I missing anything? If not, can we correct it? The btree root blocks are dynamic. mkfs.xfs puts them in a fixed place, just like growfs does, but the moment you split a root block, it moves from that location. Hence the only way to reliably find the root btree block is to look up the point in the AGF/AGI, and that's what the document shows. IOWs, the ordering in the document is not important - the linkage is - as the root blocks can end up *anywhere* in the AG. e.g: $ sudo xfs_db -r -c "agf 0" -c p /dev/vda magicnum = 0x58414746 versionnum = 1 seqno = 0 length = 262144 bnoroot = 596 cntroot = 1003 bnolevel = 2 cntlevel = 2 .... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
