diff options
Diffstat (limited to 'fs/xfs/libxfs/xfs_rmap_btree.c')
| -rw-r--r-- | fs/xfs/libxfs/xfs_rmap_btree.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c index 17b8eeb34ac8..9c0585e7db1f 100644 --- a/fs/xfs/libxfs/xfs_rmap_btree.c +++ b/fs/xfs/libxfs/xfs_rmap_btree.c @@ -512,6 +512,24 @@ void xfs_rmapbt_compute_maxlevels( struct xfs_mount *mp) { - mp->m_rmap_maxlevels = xfs_btree_compute_maxlevels(mp, - mp->m_rmap_mnr, mp->m_sb.sb_agblocks); + /* + * On a non-reflink filesystem, the maximum number of rmap + * records is the number of blocks in the AG, hence the max + * rmapbt height is log_$maxrecs($agblocks). However, with + * reflink each AG block can have up to 2^32 (per the refcount + * record format) owners, which means that theoretically we + * could face up to 2^64 rmap records. + * + * That effectively means that the max rmapbt height must be + * XFS_BTREE_MAXLEVELS. "Fortunately" we'll run out of AG + * blocks to feed the rmapbt long before the rmapbt reaches + * maximum height. The reflink code uses ag_resv_critical to + * disallow reflinking when less than 10% of the per-AG metadata + * block reservation since the fallback is a regular file copy. + */ + if (xfs_sb_version_hasreflink(&mp->m_sb)) + mp->m_rmap_maxlevels = XFS_BTREE_MAXLEVELS; + else + mp->m_rmap_maxlevels = xfs_btree_compute_maxlevels(mp, + mp->m_rmap_mnr, mp->m_sb.sb_agblocks); } |