| Message ID | 20170919181041.GC7112@magnolia (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Tue, Sep 19, 2017 at 11:10:41AM -0700, Darrick J. Wong wrote: > We call __xfs_ag_resv_init to make a per-AG reservation for each AG. > This makes the reservation per-AG, not per-filesystem. Therefore, it > is incorrect to adjust m_ag_max_usable for each AG. Adjust it only > when we're reserving AG 0's blocks so that we only do it once per fs. > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > --- Reviewed-by: Brian Foster <bfoster@redhat.com> > fs/xfs/libxfs/xfs_ag_resv.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c > index b008ff3..df3e600 100644 > --- a/fs/xfs/libxfs/xfs_ag_resv.c > +++ b/fs/xfs/libxfs/xfs_ag_resv.c > @@ -156,7 +156,8 @@ __xfs_ag_resv_free( > trace_xfs_ag_resv_free(pag, type, 0); > > resv = xfs_perag_resv(pag, type); > - pag->pag_mount->m_ag_max_usable += resv->ar_asked; > + if (pag->pag_agno == 0) > + pag->pag_mount->m_ag_max_usable += resv->ar_asked; > /* > * AGFL blocks are always considered "free", so whatever > * was reserved at mount time must be given back at umount. > @@ -216,7 +217,14 @@ __xfs_ag_resv_init( > return error; > } > > - mp->m_ag_max_usable -= ask; > + /* > + * Reduce the maximum per-AG allocation length by however much we're > + * trying to reserve for an AG. Since this is a filesystem-wide > + * counter, we only make the adjustment for AG 0. This assumes that > + * there aren't any AGs hungrier for per-AG reservation than AG 0. > + */ > + if (pag->pag_agno == 0) > + mp->m_ag_max_usable -= ask; > > resv = xfs_perag_resv(pag, type); > resv->ar_asked = ask; > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Sep 19, 2017 at 11:10:41AM -0700, Darrick J. Wong wrote: > We call __xfs_ag_resv_init to make a per-AG reservation for each AG. > This makes the reservation per-AG, not per-filesystem. Therefore, it > is incorrect to adjust m_ag_max_usable for each AG. Adjust it only > when we're reserving AG 0's blocks so that we only do it once per fs. This looks correct to me, but I hate how we manipulate a per-mount value. Is there a way we can just move this to the caller? -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Sep 21, 2017 at 07:04:21AM -0700, Christoph Hellwig wrote: > On Tue, Sep 19, 2017 at 11:10:41AM -0700, Darrick J. Wong wrote: > > We call __xfs_ag_resv_init to make a per-AG reservation for each AG. > > This makes the reservation per-AG, not per-filesystem. Therefore, it > > is incorrect to adjust m_ag_max_usable for each AG. Adjust it only > > when we're reserving AG 0's blocks so that we only do it once per fs. > > This looks correct to me, but I hate how we manipulate a per-mount > value. Is there a way we can just move this to the caller? I'm not sure which caller you're referring to -- if you mean xfs_ag_resv_init, then we'd still have the "if (pag->agno == 0) xfs_mod_fdblocks(...)"; and if xfs_fs_reserve_ag_blocks then you'd have to bubble the two ask values up out of xfs_ag_resv_init, which also seems like a layering violation. Modifying fdblocks in __xfs_ag_resv_init (Dave I think is sharpening his axe on that) smells kinda funny but it's less code intensive. <confused> --D > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c index b008ff3..df3e600 100644 --- a/fs/xfs/libxfs/xfs_ag_resv.c +++ b/fs/xfs/libxfs/xfs_ag_resv.c @@ -156,7 +156,8 @@ __xfs_ag_resv_free( trace_xfs_ag_resv_free(pag, type, 0); resv = xfs_perag_resv(pag, type); - pag->pag_mount->m_ag_max_usable += resv->ar_asked; + if (pag->pag_agno == 0) + pag->pag_mount->m_ag_max_usable += resv->ar_asked; /* * AGFL blocks are always considered "free", so whatever * was reserved at mount time must be given back at umount. @@ -216,7 +217,14 @@ __xfs_ag_resv_init( return error; } - mp->m_ag_max_usable -= ask; + /* + * Reduce the maximum per-AG allocation length by however much we're + * trying to reserve for an AG. Since this is a filesystem-wide + * counter, we only make the adjustment for AG 0. This assumes that + * there aren't any AGs hungrier for per-AG reservation than AG 0. + */ + if (pag->pag_agno == 0) + mp->m_ag_max_usable -= ask; resv = xfs_perag_resv(pag, type); resv->ar_asked = ask;
We call __xfs_ag_resv_init to make a per-AG reservation for each AG. This makes the reservation per-AG, not per-filesystem. Therefore, it is incorrect to adjust m_ag_max_usable for each AG. Adjust it only when we're reserving AG 0's blocks so that we only do it once per fs. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> --- fs/xfs/libxfs/xfs_ag_resv.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html