gfs2: Add per-reservation reserved block accounting

Add a rs_reserved field to struct gfs2_blkreserv to keep track of the number of
blocks reserved by this particular reservation, and a rd_reserved field to
struct gfs2_rgrpd to keep track of the total number of reserved blocks in the
resource group.  Those blocks are exclusively reserved, as opposed to the
rs_requested / rd_requested blocks which are tracked in the reservation tree
(rd_rstree) and which can be stolen if necessary.

When making a reservation with gfs2_inplace_reserve, rs_reserved is set to
somewhere between ap->min_target and ap->target depending on the number of free
blocks in the resource group.  When allocating blocks with gfs2_alloc_blocks,
rs_reserved is decremented accordingly.  Eventually, any reserved but not
consumed blocks are returned to the resource group by gfs2_inplace_release.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 0640d0c70a75e6..2679ba54798c85 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -107,6 +107,7 @@ struct gfs2_rgrpd {
 	u32 rd_bitbytes;		/* number of bytes in data bitmaps */
 	u32 rd_free;
 	u32 rd_requested;		/* number of blocks in rd_rstree */
+	u32 rd_reserved;		/* number of reserved blocks */
 	u32 rd_free_clone;
 	u32 rd_dinodes;
 	u64 rd_igeneration;
@@ -292,6 +293,7 @@ struct gfs2_blkreserv {
 	struct gfs2_rgrpd *rs_rgd;
 	u64 rs_start;
 	u32 rs_requested;
+	u32 rs_reserved;              /* number of reserved blocks */
 };
 
 /*