GFS2: Fix & clean up GFS2 rename

This patch fixes a locking issue in the rename code by ensuring that we hold
the per sb rename lock over both directory and "other" renames which involve
different parent directories.

At the same time, this moved the (only called from one place) function
gfs2_ok_to_move into the file that its called from, so we can mark it
static. This should make a code a bit easier to follow.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Peter Staubach <staubach@redhat.com>

1 files changed, 60 insertions, 11 deletions

diff --git a/fs/gfs2/ops_inode.c b/fs/gfs2/ops_inode.c
index 35f6f032a026..534e1e2c65ca 100644
--- a/fs/gfs2/ops_inode.c
+++ b/fs/gfs2/ops_inode.c
@@ -589,6 +589,54 @@ static int gfs2_mknod(struct inode *dir, struct dentry *dentry, int mode,
         return 0;
 }
 
+/*
+ * gfs2_ok_to_move - check if it's ok to move a directory to another directory
+ * @this: move this
+ * @to: to here
+ *
+ * Follow @to back to the root and make sure we don't encounter @this
+ * Assumes we already hold the rename lock.
+ *
+ * Returns: errno
+ */
+
+static int gfs2_ok_to_move(struct gfs2_inode *this, struct gfs2_inode *to)
+{
+        struct inode *dir = &to->i_inode;
+        struct super_block *sb = dir->i_sb;
+        struct inode *tmp;
+        struct qstr dotdot;
+        int error = 0;
+
+        gfs2_str2qstr(&dotdot, "..");
+
+        igrab(dir);
+
+        for (;;) {
+                if (dir == &this->i_inode) {
+                        error = -EINVAL;
+                        break;
+                }
+                if (dir == sb->s_root->d_inode) {
+                        error = 0;
+                        break;
+                }
+
+                tmp = gfs2_lookupi(dir, &dotdot, 1);
+                if (IS_ERR(tmp)) {
+                        error = PTR_ERR(tmp);
+                        break;
+                }
+
+                iput(dir);
+                dir = tmp;
+        }
+
+        iput(dir);
+
+        return error;
+}
+
 /**
  * gfs2_rename - Rename a file
  * @odir: Parent directory of old file name
@@ -607,7 +655,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
         struct gfs2_inode *ip = GFS2_I(odentry->d_inode);
         struct gfs2_inode *nip = NULL;
         struct gfs2_sbd *sdp = GFS2_SB(odir);
-        struct gfs2_holder ghs[5], r_gh;
+        struct gfs2_holder ghs[5], r_gh = { .gh_gl = NULL, };
         struct gfs2_rgrpd *nrgd;
         unsigned int num_gh;
         int dir_rename = 0;
@@ -621,19 +669,20 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
                         return 0;
         }
 
-        /* Make sure we aren't trying to move a dirctory into it's subdir */
 
-        if (S_ISDIR(ip->i_inode.i_mode) && odip != ndip) {
-                dir_rename = 1;
-
-                error = gfs2_glock_nq_init(sdp->sd_rename_gl, LM_ST_EXCLUSIVE, 0,
-                                           &r_gh);
+        if (odip != ndip) {
+                error = gfs2_glock_nq_init(sdp->sd_rename_gl, LM_ST_EXCLUSIVE,
+                                           0, &r_gh);
                 if (error)
                         goto out;
 
-                error = gfs2_ok_to_move(ip, ndip);
-                if (error)
-                        goto out_gunlock_r;
+                if (S_ISDIR(ip->i_inode.i_mode)) {
+                        dir_rename = 1;
+                        /* don't move a dirctory into it's subdir */
+                        error = gfs2_ok_to_move(ip, ndip);
+                        if (error)
+                                goto out_gunlock_r;
+                }
         }
 
         num_gh = 1;
@@ -829,7 +878,7 @@ out_gunlock:
                 gfs2_holder_uninit(ghs + x);
         }
 out_gunlock_r:
-        if (dir_rename)
+        if (r_gh.gh_gl)
                 gfs2_glock_dq_uninit(&r_gh);
 out:
         return error;