diff options
Diffstat (limited to 'fs/xfs/libxfs/xfs_rmap_btree.c')
| -rw-r--r-- | fs/xfs/libxfs/xfs_rmap_btree.c | 40 |
1 files changed, 21 insertions, 19 deletions
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c index f3c4d0965cc9..85caeb14e4db 100644 --- a/fs/xfs/libxfs/xfs_rmap_btree.c +++ b/fs/xfs/libxfs/xfs_rmap_btree.c @@ -535,30 +535,32 @@ xfs_rmapbt_maxrecs( } /* Compute the maximum height of an rmap btree. */ -void +unsigned int xfs_rmapbt_compute_maxlevels( - struct xfs_mount *mp) + struct xfs_mount *mp) { + if (!xfs_has_reflink(mp)) { + /* + * If there's no block sharing, compute the maximum rmapbt + * height assuming one rmap record per AG block. + */ + return xfs_btree_compute_maxlevels(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. + * Compute the asymptotic maxlevels for an rmapbt on a reflink fs. * - * 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. + * On a reflink filesystem, 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. However, we're likely to run + * out of blocks in the AG long before that happens, which means that + * we must compute the max height based on what the btree will look + * like if it consumes almost all the blocks in the AG due to maximal + * sharing factor. */ - if (xfs_has_reflink(mp)) - mp->m_rmap_maxlevels = XFS_BTREE_MAXLEVELS; - else - mp->m_rmap_maxlevels = xfs_btree_compute_maxlevels( - mp->m_rmap_mnr, mp->m_sb.sb_agblocks); + return xfs_btree_compute_maxlevels_size(mp->m_sb.sb_agblocks, + mp->m_rmap_mnr[1]); } /* Calculate the refcount btree size for some records. */ |