[PATCH 067/119] xfs: refcount btree requires more reserved space

Darrick J. Wong
2016-06-17T01:25:09Z

The reference count btree is allocated from the free space, which
means that we have to ensure that an AG can't run out of free space
while performing a refcount operation. In the pathological case each
AG block has its own refcntbt record, so we have to keep that much
space available.

v2: Calculate the maximum possible size of the rmap and refcount
btrees based on minimally-full btree blocks. This increases the
per-AG block reservations to handle the worst case btree size.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/libxfs/xfs_alloc.c | 3 +++
fs/xfs/libxfs/xfs_refcount_btree.c | 23 +++++++++++++++++++++++
fs/xfs/libxfs/xfs_refcount_btree.h | 4 ++++
3 files changed, 30 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index be5d0df..c46db76 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -38,6 +38,7 @@
#include "xfs_buf_item.h"
#include "xfs_log.h"
#include "xfs_ag_resv.h"
+#include "xfs_refcount_btree.h"

struct workqueue_struct *xfs_alloc_wq;

@@ -138,6 +139,8 @@ xfs_alloc_ag_max_usable(struct xfs_mount *mp)
/* rmap root block + full tree split on full AG */
blocks += 1 + (2 * mp->m_ag_maxlevels) - 1;
}
+ if (xfs_sb_version_hasreflink(&mp->m_sb))
+ blocks += xfs_refcountbt_max_size(mp);

return mp->m_sb.sb_agblocks - blocks;
}
diff --git a/fs/xfs/libxfs/xfs_refcount_btree.c b/fs/xfs/libxfs/xfs_refcount_btree.c
index 7093c71..a944fca 100644
--- a/fs/xfs/libxfs/xfs_refcount_btree.c
+++ b/fs/xfs/libxfs/xfs_refcount_btree.c
@@ -373,3 +373,26 @@ xfs_refcountbt_compute_maxlevels(
mp->m_refc_maxlevels = xfs_btree_compute_maxlevels(mp,
mp->m_refc_mnr, mp->m_sb.sb_agblocks);
}
+
+/* Calculate the refcount btree size for some records. */
+xfs_extlen_t
+xfs_refcountbt_calc_size(
+ struct xfs_mount *mp,
+ unsigned long long len)
+{
+ return xfs_btree_calc_size(mp, mp->m_refc_mnr, len);
+}
+
+/*
+ * Calculate the maximum refcount btree size.
+ */
+xfs_extlen_t
+xfs_refcountbt_max_size(
+ struct xfs_mount *mp)
+{
+ /* Bail out if we're uninitialized, which can happen in mkfs. */
+ if (mp->m_refc_mxr[0] == 0)
+ return 0;
+
+ return xfs_refcountbt_calc_size(mp, mp->m_sb.sb_agblocks);
+}
diff --git a/fs/xfs/libxfs/xfs_refcount_btree.h b/fs/xfs/libxfs/xfs_refcount_btree.h
index 9e9ad7c..780b02f 100644
--- a/fs/xfs/libxfs/xfs_refcount_btree.h
+++ b/fs/xfs/libxfs/xfs_refcount_btree.h
@@ -64,4 +64,8 @@ extern int xfs_refcountbt_maxrecs(struct xfs_mount *mp, int blocklen,
bool leaf);
extern void xfs_refcountbt_compute_maxlevels(struct xfs_mount *mp);

+extern xfs_extlen_t xfs_refcountbt_calc_size(struct xfs_mount *mp,
+ unsigned long long len);
+extern xfs_extlen_t xfs_refcountbt_max_size(struct xfs_mount *mp);
+
#endif /* __XFS_REFCOUNT_BTREE_H__ */