On Mon, Mar 18, 2013 at 05:38:09PM -0400, Brian Foster wrote:
> The mkfs code currently creates a single free space extent record
> for each of the bno and cnt btrees in each AG. The start block of
> the record is pushed forward on the AG that hosts an internal log.
> If the log happens to consume all available space in the AG, the
> start block becomes equal to sb->sb_agblocks and thus invalid.
> This causes xfs_repair to complain.
> For example, the following sequence:
> mkfs.xfs -d file,name=./fs.img,size=50g,agsize=16m
> xfs_repair ./fs.img
> ... produces the following xfs_repair output:
> Phase 1 - find and verify superblock...
> Phase 2 - using internal log
> - scan filesystem freespace and inode maps...
> invalid start block 4096 in record 0 of bno btree block 1600/1
> invalid start block 4096 in record 0 of cnt btree block 1600/2
> - found root inode chunk
> xfs_repair appears to correct the numrecs value such that subsequent
> checks are successful. The sequence above is pulled from xfstests
> Modify mkfs.xfs such that we check the block count value of the
> free space record for the log AG after the log is accounted for. If
> no space is left for the record, reset the record count to 0.
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
> mkfs/xfs_mkfs.c | 6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index c84448e..c4ae15b 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -2594,6 +2594,9 @@ an AG size that is one stripe unit smaller, for example
> arec->ar_blockcount = cpu_to_be32(agsize -
> + if (!arec->ar_blockcount)
> + block->bb_numrecs = cpu_to_be16(0);
You don't need to endian swap zero. block->bb_numrecs = 0; is just
fine. I'd also add a comment to explain why this is being done....