On Thu, Jan 16, 2020 at 10:59:57PM -0800, Christoph Hellwig wrote:
> On Thu, Jan 16, 2020 at 10:24:41PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > Refactor xfs_read_agf and xfs_alloc_read_agf to return EAGAIN if the
> > caller passed TRYLOCK and we weren't able to get the lock; and change
> > the callers to recognize this.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > ---
> > fs/xfs/libxfs/xfs_alloc.c | 31 +++++++++++++++----------------
> > fs/xfs/libxfs/xfs_bmap.c | 9 +++++----
> > fs/xfs/xfs_filestream.c | 11 ++++++-----
> > 3 files changed, 26 insertions(+), 25 deletions(-)
> >
> >
> > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> > index 83273975df77..26f3e4db84e0 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.c
> > +++ b/fs/xfs/libxfs/xfs_alloc.c
> > @@ -2502,13 +2502,15 @@ xfs_alloc_fix_freelist(
> >
> > if (!pag->pagf_init) {
> > error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> > - if (error)
> > - goto out_no_agbp;
> > - if (!pag->pagf_init) {
> > + if (error == -EAGAIN) {
> > + /* Couldn't lock the AGF so skip this AG. */
> > ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> > ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> > - goto out_agbp_relse;
> > + error = 0;
> > + goto out_no_agbp;
> > }
> > + if (error)
> > + goto out_no_agbp;
>
> I wonder if something like:
>
> if (error) {
> if (error == -EAGAIN) {
> /* Couldn't lock the AGF so skip this AG. */
> ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> error = 0;
> }
> goto out_no_agbp;
> }
>
> would be a little nicer here?
> > @@ -2533,13 +2535,15 @@ xfs_alloc_fix_freelist(
> > */
> > if (!agbp) {
> > error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> > - if (error)
> > - goto out_no_agbp;
> > - if (!agbp) {
> > + if (error == -EAGAIN) {
> > + /* Couldn't lock the AGF so skip this AG. */
> > ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> > ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> > + error = 0;
> > goto out_no_agbp;
> > }
> > + if (error)
> > + goto out_no_agbp;
> > }
>
> Same here. Also shouldn't those asserts just move into
> xfs_alloc_read_agf or go away now that we have a proper return value
> and not the magic NULL buffer?
I'll move the assert into xfs_alloc_read_agf, so these all turn into:
if (error) {
if (error == -EAGAIN)
error = 0;
goto next ag;
}
>
> > + error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
> > + if (error)
> > return error;
> > + xfs_trans_brelse(tp, bp);
> > return 0;
>
> Maybe simplify this further to:
>
> error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
> if (!error)
> xfs_trans_brelse(tp, bp);
> return error;
Ok.
> > @@ -2958,12 +2962,9 @@ xfs_read_agf(
> > trace_xfs_read_agf(mp, agno);
> >
> > ASSERT(agno != NULLAGNUMBER);
> > - error = xfs_trans_read_buf(
> > - mp, tp, mp->m_ddev_targp,
> > + error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
>
> This hunk should probably go into the patch that changed the
> xfs_trans_read_buf return value instead.
Ok.
> > + if (error == -EAGAIN) {
> > + /* Couldn't lock the AGF, so skip this AG. */
> > *notinit = 1;
> > + error = 0;
> > goto out;
> > }
> > + if (error)
> > + goto out;
>
> Should probably be:
>
> if (error) {
> if (error == -EAGAIN) {
> /* Couldn't lock the AGF, so skip this AG. */
> *notinit = 1;
> error = 0;
> }
> goto out;
Fixed.
--D
