On Wed, May 12, 2021 at 08:52:25AM -0400, Brian Foster wrote: > On Thu, May 06, 2021 at 05:20:50PM +1000, Dave Chinner wrote: > > From: Dave Chinner <dchinner@xxxxxxxxxx> > > > > xfs_dialloc_select_ag() does a lot of repetitive work. It first > > calls xfs_ialloc_ag_select() to select the AG to start allocation > > attempts in, which can do up to two entire loops across the perags > > that inodes can be allocated in. This is simply checking if there is > > spce available to allocate inodes in an AG, and it returns when it > > finds the first candidate AG. > > > > xfs_dialloc_select_ag() then does it's own iterative walk across > > all the perags locking the AGIs and trying to allocate inodes from > > the locked AG. It also doesn't limit the search to mp->m_maxagi, > > so it will walk all AGs whether they can allocate inodes or not. > > > > Hence if we are really low on inodes, we could do almost 3 entire > > walks across the whole perag range before we find an allocation > > group we can allocate inodes in or report ENOSPC. > > > > Because xfs_ialloc_ag_select() returns on the first candidate AG it > > finds, we can simply do these checks directly in > > xfs_dialloc_select_ag() before we lock and try to allocate inodes. > > This reduces the inode allocation pass down to 2 perag sweeps at > > most - one for aligned inode cluster allocation and if we can't > > allocate full, aligned inode clusters anywhere we'll do another pass > > trying to do sparse inode cluster allocation. > > > > This also removes a big chunk of duplicate code. > > > > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> > > --- > > fs/xfs/libxfs/xfs_ialloc.c | 221 +++++++++++++------------------------ > > 1 file changed, 75 insertions(+), 146 deletions(-) > > > > diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c > > index 872591e8f5cb..b22556556bba 100644 > > --- a/fs/xfs/libxfs/xfs_ialloc.c > > +++ b/fs/xfs/libxfs/xfs_ialloc.c > ... > > @@ -1778,10 +1669,41 @@ xfs_dialloc_select_ag( > > break; > > } > > > > + if (!pag->pagi_freecount) > > + goto nextag; > > It looks like this would never allow for allocation of new inode > chunks..? > > > + if (!okalloc) > > + goto nextag; I guess I never tested this patch in isolation, and I fixed the bug in one of the following patches. This should be: if (!pag->pagi_freecount && !okalloc) goto nextag; Fixed. -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
