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>

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 4d546df..47d0bda 100644 (file)
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -644,7 +644,6 @@ struct gfs2_sbd {
 
        int sd_rindex_uptodate;
        spinlock_t sd_rindex_spin;
-       struct mutex sd_rindex_mutex;
        struct rb_root sd_rindex_tree;
        unsigned int sd_rgrps;
        unsigned int sd_max_rg_data;

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index a55baa7..ae5e0a4 100644 (file)
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -83,7 +83,6 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb)
        spin_lock_init(&sdp->sd_statfs_spin);
 
        spin_lock_init(&sdp->sd_rindex_spin);
-       mutex_init(&sdp->sd_rindex_mutex);
        sdp->sd_rindex_tree.rb_node = NULL;
 
        INIT_LIST_HEAD(&sdp->sd_jindex_list);

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index e09370e..6ff9f17 100644 (file)
--- 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;
 }