GFS2: Eliminate sd_rindex_mutex

Over time, we've slowly eliminated the use of sd_rindex_mutex.
Up to this point, it was only used in two places: function
gfs2_ri_total (which totals the file system size by reading
and parsing the rindex file) and function gfs2_rindex_update
which updates the rgrps in memory. Both of these functions have
the rindex glock to protect them, so the rindex is unnecessary.
Since gfs2_grow writes to the rindex via the meta_fs, the mutex
is in the wrong order according to the normal rules. This patch
eliminates the mutex entirely to avoid the problem.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 10 insertions, 12 deletions

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index e09370eec590..6ff9f17f9ac2 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -540,7 +540,6 @@ u64 gfs2_ri_total(struct gfs2_sbd *sdp)
         struct file_ra_state ra_state;
         int error, rgrps;
 
-        mutex_lock(&sdp->sd_rindex_mutex);
         file_ra_state_init(&ra_state, inode->i_mapping);
         for (rgrps = 0;; rgrps++) {
                 loff_t pos = rgrps * sizeof(struct gfs2_rindex);
@@ -553,11 +552,10 @@ u64 gfs2_ri_total(struct gfs2_sbd *sdp)
                         break;
                 total_data += be32_to_cpu(((struct gfs2_rindex *)buf)->ri_data);
         }
-        mutex_unlock(&sdp->sd_rindex_mutex);
         return total_data;
 }
 
-static void rgd_insert(struct gfs2_rgrpd *rgd)
+static int rgd_insert(struct gfs2_rgrpd *rgd)
 {
         struct gfs2_sbd *sdp = rgd->rd_sbd;
         struct rb_node **newn = &sdp->sd_rindex_tree.rb_node, *parent = NULL;
@@ -573,11 +571,13 @@ static void rgd_insert(struct gfs2_rgrpd *rgd)
                 else if (rgd->rd_addr > cur->rd_addr)
                         newn = &((*newn)->rb_right);
                 else
-                        return;
+                        return -EEXIST;
         }
 
         rb_link_node(&rgd->rd_node, parent, newn);
         rb_insert_color(&rgd->rd_node, &sdp->sd_rindex_tree);
+        sdp->sd_rgrps++;
+        return 0;
 }
 
 /**
@@ -631,10 +631,12 @@ static int read_rindex_entry(struct gfs2_inode *ip,
         if (rgd->rd_data > sdp->sd_max_rg_data)
                 sdp->sd_max_rg_data = rgd->rd_data;
         spin_lock(&sdp->sd_rindex_spin);
-        rgd_insert(rgd);
-        sdp->sd_rgrps++;
+        error = rgd_insert(rgd);
         spin_unlock(&sdp->sd_rindex_spin);
-        return error;
+        if (!error)
+                return 0;
+
+        error = 0; /* someone else read in the rgrp; free it and ignore it */
 
 fail:
         kfree(rgd->rd_bits);
@@ -695,22 +697,18 @@ int gfs2_rindex_update(struct gfs2_sbd *sdp)
 
         /* Read new copy from disk if we don't have the latest */
         if (!sdp->sd_rindex_uptodate) {
-                mutex_lock(&sdp->sd_rindex_mutex);
                 if (!gfs2_glock_is_locked_by_me(gl)) {
                         error = gfs2_glock_nq_init(gl, LM_ST_SHARED, 0, &ri_gh);
                         if (error)
-                                goto out_unlock;
+                                return error;
                         unlock_required = 1;
                 }
                 if (!sdp->sd_rindex_uptodate)
                         error = gfs2_ri_update(ip);
                 if (unlock_required)
                         gfs2_glock_dq_uninit(&ri_gh);
-out_unlock:
-                mutex_unlock(&sdp->sd_rindex_mutex);
         }
 
-
         return error;
 }