Ocfs2/move_extents: find the victim alloc group, where the given #blk fits.

This function tries locate the right alloc group, where a given physical block
resides, it returns the caller a buffer_head of victim group descriptor, and also
the offset of block in this group, by passing the block number.

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>

diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index 78db10d4c7f116e35a6af5e2878f69f48087961a..68e00b47332b4047db1ccfaec712ddec46e26174 100644 (file)
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -351,3 +351,107 @@ out:
 
        return ret;
 }
+
+/*
+ * find the victim alloc group, where #blkno fits.
+ */
+static int ocfs2_find_victim_alloc_group(struct inode *inode,
+                                        u64 vict_blkno,
+                                        int type, int slot,
+                                        int *vict_bit,
+                                        struct buffer_head **ret_bh)
+{
+       int ret, i, blocks_per_unit = 1;
+       u64 blkno;
+       char namebuf[40];
+
+       struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+       struct buffer_head *ac_bh = NULL, *gd_bh = NULL;
+       struct ocfs2_chain_list *cl;
+       struct ocfs2_chain_rec *rec;
+       struct ocfs2_dinode *ac_dinode;
+       struct ocfs2_group_desc *bg;
+
+       ocfs2_sprintf_system_inode_name(namebuf, sizeof(namebuf), type, slot);
+       ret = ocfs2_lookup_ino_from_name(osb->sys_root_inode, namebuf,
+                                        strlen(namebuf), &blkno);
+       if (ret) {
+               ret = -ENOENT;
+               goto out;
+       }
+
+       ret = ocfs2_read_blocks_sync(osb, blkno, 1, &ac_bh);
+       if (ret) {
+               mlog_errno(ret);
+               goto out;
+       }
+
+       ac_dinode = (struct ocfs2_dinode *)ac_bh->b_data;
+       cl = &(ac_dinode->id2.i_chain);
+       rec = &(cl->cl_recs[0]);
+
+       if (type == GLOBAL_BITMAP_SYSTEM_INODE)
+               blocks_per_unit <<= (osb->s_clustersize_bits -
+                                               inode->i_sb->s_blocksize_bits);
+       /*
+        * 'vict_blkno' was out of the valid range.
+        */
+       if ((vict_blkno < le64_to_cpu(rec->c_blkno)) ||
+           (vict_blkno >= (le32_to_cpu(ac_dinode->id1.bitmap1.i_total) *
+                               blocks_per_unit))) {
+               ret = -EINVAL;
+               goto out;
+       }
+
+       for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i++) {
+
+               rec = &(cl->cl_recs[i]);
+               if (!rec)
+                       continue;
+
+               bg = NULL;
+
+               do {
+                       if (!bg)
+                               blkno = le64_to_cpu(rec->c_blkno);
+                       else
+                               blkno = le64_to_cpu(bg->bg_next_group);
+
+                       if (gd_bh) {
+                               brelse(gd_bh);
+                               gd_bh = NULL;
+                       }
+
+                       ret = ocfs2_read_blocks_sync(osb, blkno, 1, &gd_bh);
+                       if (ret) {
+                               mlog_errno(ret);
+                               goto out;
+                       }
+
+                       bg = (struct ocfs2_group_desc *)gd_bh->b_data;
+
+                       if (vict_blkno < (le64_to_cpu(bg->bg_blkno) +
+                                               le16_to_cpu(bg->bg_bits))) {
+
+                               *ret_bh = gd_bh;
+                               *vict_bit = (vict_blkno - blkno) /
+                                                       blocks_per_unit;
+                               mlog(0, "find the victim group: #%llu, "
+                                    "total_bits: %u, vict_bit: %u\n",
+                                    blkno, le16_to_cpu(bg->bg_bits),
+                                    *vict_bit);
+                               goto out;
+                       }
+
+               } while (le64_to_cpu(bg->bg_next_group));
+       }
+
+       ret = -EINVAL;
+out:
+       brelse(ac_bh);
+
+       /*
+        * caller has to release the gd_bh properly.
+        */
+       return ret;
+}