GFS2: Make rename not save dirent location

commit 19aeb5a6 upstream.

This patch fixes a regression in the patch "GFS2: Remember directory
insert point", commit 2b47dad8.
The problem had to do with the rename function: The function found
space for the new dirent, and remembered that location. But then the
old dirent was removed, which often moved the eligible location for
the renamed dirent. Putting the new dirent at the saved location
caused file system corruption.

This patch adds a new "save_loc" variable to struct gfs2_diradd.
If 1, the dirent location is saved. If 0, the dirent location is not
saved and the buffer_head is released as per previous behavior.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

fs/gfs2/dir.c

@@ -2100,8 +2100,13 @@ int gfs2_diradd_alloc_required(struct inode *inode, const struct qstr *name,
 	}
 	if (IS_ERR(dent))
 		return PTR_ERR(dent);
-	da->bh = bh;
-	da->dent = dent;
+
+	if (da->save_loc) {
+		da->bh = bh;
+		da->dent = dent;
+	} else {
+		brelse(bh);
+	}
 	return 0;
 }
 

fs/gfs2/dir.h

@@ -23,6 +23,7 @@ struct gfs2_diradd {
 	unsigned nr_blocks;
 	struct gfs2_dirent *dent;
 	struct buffer_head *bh;
+	int save_loc;
 };
 
 extern struct inode *gfs2_dir_search(struct inode *dir,

fs/gfs2/inode.c

@@ -600,7 +600,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	int error, free_vfs_inode = 0;
 	u32 aflags = 0;
 	unsigned blocks = 1;
-	struct gfs2_diradd da = { .bh = NULL, };
+	struct gfs2_diradd da = { .bh = NULL, .save_loc = 1, };
 
 	if (!name->len || name->len > GFS2_FNAMESIZE)
 		return -ENAMETOOLONG;
@@ -897,7 +897,7 @@ static int gfs2_link(struct dentry *old_dentry, struct inode *dir,
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_holder ghs[2];
 	struct buffer_head *dibh;
-	struct gfs2_diradd da = { .bh = NULL, };
+	struct gfs2_diradd da = { .bh = NULL, .save_loc = 1, };
 	int error;
 
 	if (S_ISDIR(inode->i_mode))
@@ -1335,7 +1335,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 	struct gfs2_rgrpd *nrgd;
 	unsigned int num_gh;
 	int dir_rename = 0;
-	struct gfs2_diradd da = { .nr_blocks = 0, };
+	struct gfs2_diradd da = { .nr_blocks = 0, .save_loc = 0, };
 	unsigned int x;
 	int error;