gfs2: separate holder for rgrps in gfs2_rename

Before this patch, gfs2_rename added a holder for the rgrp glock to
its array of holders, ghs. There's nothing wrong with that, but this
patch separates it into a separate holder. This is done to ensure
it's always locked last as per the proper glock lock ordering,
and also to pave the way for a future patch in which we will
lock the non-rgrp glocks asynchronously.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 2e2a8a2fb51dd6b95e478ad711ace6ac940d9852..50eeb15c6f4fdab22a3e40cc2f405c431cb5fa50 100644 (file)
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -1348,7 +1348,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
        struct gfs2_inode *ip = GFS2_I(d_inode(odentry));
        struct gfs2_inode *nip = NULL;
        struct gfs2_sbd *sdp = GFS2_SB(odir);
-       struct gfs2_holder ghs[5], r_gh;
+       struct gfs2_holder ghs[4], r_gh, rd_gh;
        struct gfs2_rgrpd *nrgd;
        unsigned int num_gh;
        int dir_rename = 0;
@@ -1357,6 +1357,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
        int error;
 
        gfs2_holder_mark_uninitialized(&r_gh);
+       gfs2_holder_mark_uninitialized(&rd_gh);
        if (d_really_is_positive(ndentry)) {
                nip = GFS2_I(d_inode(ndentry));
                if (ip == nip)
@@ -1398,13 +1399,6 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
        if (nip) {
                gfs2_holder_init(nip->i_gl, LM_ST_EXCLUSIVE, 0, ghs + num_gh);
                num_gh++;
-               /* grab the resource lock for unlink flag twiddling 
-                * this is the case of the target file already existing
-                * so we unlink before doing the rename
-                */
-               nrgd = gfs2_blk2rgrpd(sdp, nip->i_no_addr, 1);
-               if (nrgd)
-                       gfs2_holder_init(nrgd->rd_gl, LM_ST_EXCLUSIVE, 0, ghs + num_gh++);
        }
 
        for (x = 0; x < num_gh; x++) {
@@ -1413,6 +1407,22 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
                        goto out_gunlock;
        }
 
+       if (nip) {
+               /* Grab the resource group glock for unlink flag twiddling.
+                * This is the case where the target dinode already exists
+                * so we unlink before doing the rename.
+                */
+               nrgd = gfs2_blk2rgrpd(sdp, nip->i_no_addr, 1);
+               if (!nrgd) {
+                       error = -ENOENT;
+                       goto out_gunlock;
+               }
+               error = gfs2_glock_nq_init(nrgd->rd_gl, LM_ST_EXCLUSIVE, 0,
+                                          &rd_gh);
+               if (error)
+                       goto out_gunlock;
+       }
+
        error = -ENOENT;
        if (ip->i_inode.i_nlink == 0)
                goto out_gunlock;
@@ -1541,6 +1551,9 @@ out_gunlock_q:
                gfs2_quota_unlock(ndip);
 out_gunlock:
        gfs2_dir_no_add(&da);
+       if (gfs2_holder_initialized(&rd_gh))
+               gfs2_glock_dq_uninit(&rd_gh);
+
        while (x--) {
                gfs2_glock_dq(ghs + x);
                gfs2_holder_uninit(ghs + x);