ocfs2: properly set and use inode group alloc hint

We were setting ac->ac_last_group in ocfs2_claim_suballoc_bits from
res->sr_bg_blkno.  Unfortunately, res->sr_bg_blkno is going to be zero under
normal (non-fragmented) circumstances. The discontig block group patches
effectively turned off that feature. Fix this by correctly calculating what
the next group hint should be.

Acked-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Tested-by: Goldwyn Rodrigues <rgoldwyn@suse.de>
Signed-off-by: Tao Ma <tao.ma@oracle.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 8a009ee1f7fd..b93d7e72175a 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -62,6 +62,17 @@ struct ocfs2_suballoc_result {
         unsigned int    sr_bits;        /* How many bits we claimed */
 };
 
+static u64 ocfs2_group_from_res(struct ocfs2_suballoc_result *res)
+{
+        if (res->sr_blkno == 0)
+                return 0;
+
+        if (res->sr_bg_blkno)
+                return res->sr_bg_blkno;
+
+        return ocfs2_which_suballoc_group(res->sr_blkno, res->sr_bit_offset);
+}
+
 static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg);
 static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe);
 static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl);
@@ -1845,6 +1856,7 @@ static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
         int status;
         u16 victim, i;
         u16 bits_left = 0;
+        u64 hint = ac->ac_last_group;
         struct ocfs2_chain_list *cl;
         struct ocfs2_dinode *fe;
 
@@ -1872,7 +1884,7 @@ static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
                 goto bail;
         }
 
-        res->sr_bg_blkno = ac->ac_last_group;
+        res->sr_bg_blkno = hint;
         if (res->sr_bg_blkno) {
                 /* Attempt to short-circuit the usual search mechanism
                  * by jumping straight to the most recently used
@@ -1896,8 +1908,10 @@ static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
 
         status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits,
                                     res, &bits_left);
-        if (!status)
+        if (!status) {
+                hint = ocfs2_group_from_res(res);
                 goto set_hint;
+        }
         if (status < 0 && status != -ENOSPC) {
                 mlog_errno(status);
                 goto bail;
@@ -1920,8 +1934,10 @@ static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
                 ac->ac_chain = i;
                 status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits,
                                             res, &bits_left);
-                if (!status)
+                if (!status) {
+                        hint = ocfs2_group_from_res(res);
                         break;
+                }
                 if (status < 0 && status != -ENOSPC) {
                         mlog_errno(status);
                         goto bail;
@@ -1936,7 +1952,7 @@ set_hint:
                 if (bits_left < min_bits)
                         ac->ac_last_group = 0;
                 else
-                        ac->ac_last_group = res->sr_bg_blkno;
+                        ac->ac_last_group = hint;
         }
 
 bail: