[PATCH 2/5] xfs: add two mp member to record the alloction field layout

[zhangshida]

From: Shida Zhang <zhangshida@xxxxxxxxxx>

Add two member to support the AF(alloction field) for each *mp*,
which means now we can have 3 AFs at most:
    [ 0, AF[0] )
    [ AF[0], AF[1] )
    [ AF[1], m_sb.agcount )

where AF[N],
    start agno of the AF[N] = mp->m_sb.agcount - mp->m_af[N]

On default,
    [ 0,  m_sb.agcount)
    [ m_sb.agcount, m_sb.agcount )
    [ m_sb.agcount, m_sb.agcount )

That means the entire filesystem can be deemed as a AF 0 extending
from 0 to m_sb.agcount.

Signed-off-by: Shida Zhang <zhangshida@xxxxxxxxxx>
---
 fs/xfs/xfs_mount.h | 3 +++
 fs/xfs/xfs_super.c | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 96496f39f551..38dff08b467d 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -260,6 +260,9 @@ typedef struct xfs_mount {
 
 	/* Hook to feed dirent updates to an active online repair. */
 	struct xfs_hooks	m_dir_update_hooks;
+
+	/* Relative start agno of the AFs */
+	xfs_agnumber_t		m_af[2];
 } xfs_mount_t;
 
 #define M_IGEO(mp)		(&(mp)->m_ino_geo)
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index fbb3a1594c0d..0975ad55557e 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -2040,6 +2040,8 @@ static int xfs_init_fs_context(
 	mp->m_logbufs = -1;
 	mp->m_logbsize = -1;
 	mp->m_allocsize_log = 16; /* 64k */
+	mp->m_af[0] = 0;
+	mp->m_af[1] = 0;
 
 	xfs_hooks_init(&mp->m_dir_update_hooks);
 
-- 
2.33.0