On Wed, May 22, 2013 at 03:50:59PM -0500, Ben Myers wrote: > On Tue, May 21, 2013 at 06:02:05PM +1000, Dave Chinner wrote: > > From: Dave Chinner <dchinner@xxxxxxxxxx> > > > > xfs_attr3_leaf_unbalance() uses a temporary buffer for recombining > > the entries in two leaves when the destination leaf requires > > compaction. The temporary buffer ends up being copied back over the > > original destination buffer, so the header in the temporary buffer > > needs to contain all the information that is in the destination > > buffer. > > > > To make sure the temporary buffer is fully initialised, once we've > > set up the temporary incore header appropriately, write is back to > > the temporary buffer before starting to move entries around. > > > > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> > > > > --- > > fs/xfs/xfs_attr_leaf.c | 16 +++++++++++++--- > > 1 file changed, 13 insertions(+), 3 deletions(-) > > > > diff --git a/fs/xfs/xfs_attr_leaf.c b/fs/xfs/xfs_attr_leaf.c > > index 0bce1b3..79ece72 100644 > > --- a/fs/xfs/xfs_attr_leaf.c > > +++ b/fs/xfs/xfs_attr_leaf.c > > @@ -2181,14 +2181,24 @@ xfs_attr3_leaf_unbalance( > > struct xfs_attr_leafblock *tmp_leaf; > > struct xfs_attr3_icleaf_hdr tmphdr; > > > > - tmp_leaf = kmem_alloc(state->blocksize, KM_SLEEP); > > - memset(tmp_leaf, 0, state->blocksize); > > - memset(&tmphdr, 0, sizeof(tmphdr)); > > + tmp_leaf = kmem_zalloc(state->blocksize, KM_SLEEP); > > + > > + /* > > + * Copy the header into the temp leaf so that all the stuff > > + * not in the incore header is present and gets copied back in > > + * once we've moved all the entries. > > + */ > > + memcpy(tmp_leaf, save_leaf, xfs_attr3_leaf_hdr_size(save_leaf)); > > > > + memset(&tmphdr, 0, sizeof(tmphdr)); > > tmphdr.magic = savehdr.magic; > > tmphdr.forw = savehdr.forw; > > tmphdr.back = savehdr.back; > > tmphdr.firstused = state->blocksize; > > + > > + /* write the header to the temp buffer to initialise it */ > > + xfs_attr3_leaf_hdr_to_disk(tmp_leaf, &tmphdr); > > + > > Hrm. It seemed like the memset 0 for the incore temp header should have been > enough for the purposes of moveents. Why did you have to add this additional > hdr_to_disk? Because we've modified the tmphdr so it is different to what is in the tmp_leaf, and I'm being paranoid and not making any assumptions that a callee doesn't reread the tmphdr from the tmp_leaf. i.e. I'm initialising both the on-disk and the incore headers to be identical before we do anything else. Once bitten, twice shy. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
