xfs: store rmapbt block count in the AGF

Track the number of blocks used for the rmapbt in the AGF.  When we
get to the AG reservation code we need this counter to quickly
make our reservation during mount.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

4 files changed, 16 insertions, 3 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 776ae2f325d1..af1a72efa64c 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2264,6 +2264,7 @@ xfs_alloc_log_agf(
                 offsetof(xfs_agf_t, agf_longest),
                 offsetof(xfs_agf_t, agf_btreeblks),
                 offsetof(xfs_agf_t, agf_uuid),
+                offsetof(xfs_agf_t, agf_rmap_blocks),
                 sizeof(xfs_agf_t)
         };
 
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index f814d42c73b2..e6a8bea0f7ba 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -640,12 +640,15 @@ typedef struct xfs_agf {
         __be32          agf_btreeblks;  /* # of blocks held in AGF btrees */
         uuid_t          agf_uuid;       /* uuid of filesystem */
 
+        __be32          agf_rmap_blocks;        /* rmapbt blocks used */
+        __be32          agf_padding;            /* padding */
+
         /*
          * reserve some contiguous space for future logged fields before we add
          * the unlogged fields. This makes the range logging via flags and
          * structure offsets much simpler.
          */
-        __be64          agf_spare64[16];
+        __be64          agf_spare64[15];
 
         /* unlogged fields, written during buffer writeback. */
         __be64          agf_lsn;        /* last write sequence */
@@ -670,7 +673,8 @@ typedef struct xfs_agf {
 #define XFS_AGF_LONGEST         0x00000400
 #define XFS_AGF_BTREEBLKS       0x00000800
 #define XFS_AGF_UUID            0x00001000
-#define XFS_AGF_NUM_BITS        13
+#define XFS_AGF_RMAP_BLOCKS     0x00002000
+#define XFS_AGF_NUM_BITS        14
 #define XFS_AGF_ALL_BITS        ((1 << XFS_AGF_NUM_BITS) - 1)
 
 #define XFS_AGF_FLAGS \
@@ -686,7 +690,8 @@ typedef struct xfs_agf {
         { XFS_AGF_FREEBLKS,     "FREEBLKS" }, \
         { XFS_AGF_LONGEST,      "LONGEST" }, \
         { XFS_AGF_BTREEBLKS,    "BTREEBLKS" }, \
-        { XFS_AGF_UUID,         "UUID" }
+        { XFS_AGF_UUID,         "UUID" }, \
+        { XFS_AGF_RMAP_BLOCKS,  "RMAP_BLOCKS" }
 
 /* disk block (xfs_daddr_t) in the AG */
 #define XFS_AGF_DADDR(mp)       ((xfs_daddr_t)(1 << (mp)->m_sectbb_log))
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index bc1faebc84ec..17b8eeb34ac8 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -98,6 +98,8 @@ xfs_rmapbt_alloc_block(
         union xfs_btree_ptr     *new,
         int                     *stat)
 {
+        struct xfs_buf          *agbp = cur->bc_private.a.agbp;
+        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
         int                     error;
         xfs_agblock_t           bno;
 
@@ -124,6 +126,8 @@ xfs_rmapbt_alloc_block(
 
         xfs_trans_agbtree_delta(cur->bc_tp, 1);
         new->s = cpu_to_be32(bno);
+        be32_add_cpu(&agf->agf_rmap_blocks, 1);
+        xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
 
         XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
         *stat = 1;
@@ -143,6 +147,8 @@ xfs_rmapbt_free_block(
         bno = xfs_daddr_to_agbno(cur->bc_mp, XFS_BUF_ADDR(bp));
         trace_xfs_rmapbt_free_block(cur->bc_mp, cur->bc_private.a.agno,
                         bno, 1);
+        be32_add_cpu(&agf->agf_rmap_blocks, -1);
+        xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
         error = xfs_alloc_put_freelist(cur->bc_tp, agbp, NULL, bno, 1);
         if (error)
                 return error;
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 0f96847b90e1..0b7f986745c1 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -248,6 +248,7 @@ xfs_growfs_data_private(
                         agf->agf_roots[XFS_BTNUM_RMAPi] =
                                                 cpu_to_be32(XFS_RMAP_BLOCK(mp));
                         agf->agf_levels[XFS_BTNUM_RMAPi] = cpu_to_be32(1);
+                        agf->agf_rmap_blocks = cpu_to_be32(1);
                 }
 
                 agf->agf_flfirst = cpu_to_be32(1);