If a given AG is empty, we can totally wipe it out of the disk via this
helper by cleaning up the AG metadata blocks.
Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
---
fs/xfs/xfs_fsops.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 149 insertions(+), 0 deletions(-)
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 6623d9a..24de23f 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -706,6 +706,155 @@ error0:
}
/*
+ * This function is used to remove an empty AG out of the disk
+ * by cleaning up it's metadata info and free the related perag
+ * object.
+ */
+static int
+xfs_remove_empty_ag(
+ xfs_mount_t *mp,
+ xfs_agnumber_t agno,
+ xfs_extlen_t *nfree)
+{
+ xfs_agf_t *agf;
+ xfs_agi_t *agi;
+ xfs_buf_t *bp;
+ xfs_dsb_t *sbp;
+ xfs_agfl_t *agfl;
+ xfs_perag_t *pag;
+ __uint32_t agfl_bno;
+ __uint32_t bno_btree_blkno;
+ __uint32_t cnt_btree_blkno;
+ __uint32_t ino_btree_blkno;
+ struct xfs_btree_block *block;
+ int error;
+
+ /* Wipe out superblock in sector size */
+ error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
+ XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
+ XFS_FSS_TO_BB(mp, 1), 0, &bp);
+ if (error)
+ goto error0;
+ sbp = XFS_BUF_TO_SBP(bp);
+ memset(sbp, 0, mp->m_sb.sb_sectsize);
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ if (error)
+ goto error0;
+
+ bp = xfs_buf_get(mp->m_ddev_targp,
+ XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
+ XFS_FSS_TO_BB(mp, 1), 0);
+ if (!bp) {
+ error = ENOMEM;
+ goto error0;
+ }
+ agf = XFS_BUF_TO_AGF(bp);
+ if (nfree) {
+ /*
+ * Don't use the mp->m_sb.sb_agcount since the end
+ * AG might has different size to others.
+ */
+ *nfree = be32_to_cpu(agf->agf_length);
+ }
+ bno_btree_blkno = be32_to_cpu(agf->agf_roots[XFS_BTNUM_BNOi]);
+ cnt_btree_blkno = be32_to_cpu(agf->agf_roots[XFS_BTNUM_CNTi]);
+ memset(agf, 0, mp->m_sb.sb_sectsize);
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ if (error)
+ goto error0;
+
+ bp = xfs_buf_get(mp->m_ddev_targp,
+ XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
+ XFS_FSS_TO_BB(mp, 1), 0);
+ if (!bp) {
+ error = ENOMEM;
+ goto error0;
+ }
+ agi = XFS_BUF_TO_AGI(bp);
+ ino_btree_blkno = be32_to_cpu(agi->agi_root);
+ memset(agi, 0, mp->m_sb.sb_sectsize);
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ if (error)
+ goto error0;
+
+ bp = xfs_buf_get(mp->m_ddev_targp,
+ XFS_AGB_TO_DADDR(mp, agno, XFS_AGFL_BLOCK(mp)),
+ XFS_FSS_TO_BB(mp, 1), 0);
+ if (!bp) {
+ error = XFS_ERROR(ENOMEM);
+ goto error0;
+ }
+ agfl = XFS_BUF_TO_AGFL(bp);
+ agfl_bno = be32_to_cpu(agfl->agfl_bno[0]);
+ memset(agfl, 0, mp->m_sb.sb_sectsize);
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ if (error)
+ goto error0;
+
+ /* BNO btree root block */
+ bp = xfs_buf_get(mp->m_ddev_targp,
+ XFS_AGB_TO_DADDR(mp, agno, bno_btree_blkno),
+ BTOBB(mp->m_sb.sb_blocksize), 0);
+ if (!bp) {
+ error = XFS_ERROR(ENOMEM);
+ goto error0;
+ }
+ block = XFS_BUF_TO_BLOCK(bp);
+ memset(block, 0, mp->m_sb.sb_blocksize);
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ if (error)
+ goto error0;
+
+ /* CNT btree root block */
+ bp = xfs_buf_get(mp->m_ddev_targp,
+ XFS_AGB_TO_DADDR(mp, agno, cnt_btree_blkno),
+ BTOBB(mp->m_sb.sb_blocksize), 0);
+ if (!bp) {
+ error = XFS_ERROR(ENOMEM);
+ goto error0;
+ }
+ block = XFS_BUF_TO_BLOCK(bp);
+ memset(block, 0, mp->m_sb.sb_blocksize);
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ if (error)
+ goto error0;
+
+ /* INO btree root block */
+ bp = xfs_buf_get(mp->m_ddev_targp,
+ XFS_AGB_TO_DADDR(mp, agno, ino_btree_blkno),
+ BTOBB(mp->m_sb.sb_blocksize), 0);
+ if (!bp) {
+ error = XFS_ERROR(ENOMEM);
+ goto error0;
+ }
+ block = XFS_BUF_TO_BLOCK(bp);
+ memset(block, 0, mp->m_sb.sb_blocksize);
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ if (error)
+ goto error0;
+
+ /* Free perag object from the radix tree */
+ spin_lock(&mp->m_perag_lock);
+ pag = radix_tree_delete(&mp->m_perag_tree, agno);
+ spin_unlock(&mp->m_perag_lock);
+ ASSERT(pag);
+ ASSERT(atomic_read(&pag->pag_ref) == 0);
+ kmem_free(pag);
+
+ *nfree += xfs_ag_metadata_blocks(mp, agno);
+
+error0:
+ return error;
+}
+
+/*
* exported through ioctl XFS_IOC_FSCOUNTS
*/
--
1.7.4.1
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