On Tue, Sep 27, 2016 at 07:54:20PM -0700, Darrick J. Wong wrote: > Every time we allocate or free an extent, we might need to split the > refcount btree. Reserve some blocks in the transaction to handle > this possibility. > I'm probably not far along enough to grok how this all works, but I'm a bit confused by the requirement here. Why is generic block allocation/free a refcountbt matter? E.g., the function below is used for things like inode chunk allocation and whatnot, aren't those irrelevant to the refcountbt? Brian > (Reproduced by generic/167 over NFS atop XFS) > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > [darrick.wong@xxxxxxxxxx: add commit message] > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > --- > fs/xfs/libxfs/xfs_trans_resv.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > > diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c > index 7c840e1..a59838f 100644 > --- a/fs/xfs/libxfs/xfs_trans_resv.c > +++ b/fs/xfs/libxfs/xfs_trans_resv.c > @@ -67,7 +67,8 @@ xfs_calc_buf_res( > * Per-extent log reservation for the btree changes involved in freeing or > * allocating an extent. In classic XFS there were two trees that will be > * modified (bnobt + cntbt). With rmap enabled, there are three trees > - * (rmapbt). The number of blocks reserved is based on the formula: > + * (rmapbt). With reflink, there are four trees (refcountbt). The number of > + * blocks reserved is based on the formula: > * > * num trees * ((2 blocks/level * max depth) - 1) > * > @@ -83,6 +84,8 @@ xfs_allocfree_log_count( > blocks = num_ops * 2 * (2 * mp->m_ag_maxlevels - 1); > if (xfs_sb_version_hasrmapbt(&mp->m_sb)) > blocks += num_ops * (2 * mp->m_rmap_maxlevels - 1); > + if (xfs_sb_version_hasreflink(&mp->m_sb)) > + blocks += num_ops * (2 * mp->m_refc_maxlevels - 1); > > return blocks; > } > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" 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-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
