gfs2: Fix and clean up create / evict interaction

When gfs2_create_inode() fails after creating a new inode, it uses the
GIF_FREE_VFS_INODE and GIF_ALLOC_FAILED inode flags to communicate to
gfs2_evict_inode() which parts of the inode need to be deallocated and
destroyed.  In some error cases, the inode ends up being allocated on
disk and then accidentally left behind.  In others, the inode is
partially constructed and then not properly destroyed.  Clean this up by
completely handling the inode deallocation and destruction in
gfs2_evict_inode().

This means that gfs2_evict_inode() may now be faced with partially
constructed inodes, so add the necessary checks to cope with that.  In
particular, make sure that for incompletely constructed inodes, we're
not accessing the buffers backing the on-disk blocks; the contents may
be undefined.

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

1 files changed, 21 insertions, 14 deletions

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index b018957a1bb2..eac9b0c34aac 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -475,6 +475,12 @@ static void gfs2_dirty_inode(struct inode *inode, int flags)
 	int need_endtrans = 0;
 	int ret;
 
+	if (unlikely(!ip->i_gl)) {
+		/* This can only happen during incomplete inode creation. */
+		BUG_ON(!test_bit(GIF_ALLOC_FAILED, &ip->i_flags));
+		return;
+	}
+
 	if (unlikely(gfs2_withdrawn(sdp)))
 		return;
 	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
@@ -927,8 +933,7 @@ static int gfs2_drop_inode(struct inode *inode)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 
-	if (!test_bit(GIF_FREE_VFS_INODE, &ip->i_flags) &&
-	    inode->i_nlink &&
+	if (inode->i_nlink &&
 	    gfs2_holder_initialized(&ip->i_iopen_gh)) {
 		struct gfs2_glock *gl = ip->i_iopen_gh.gh_gl;
 		if (test_bit(GLF_DEMOTE, &gl->gl_flags))
@@ -1076,7 +1081,13 @@ static void gfs2_final_release_pages(struct gfs2_inode *ip)
 	struct inode *inode = &ip->i_inode;
 	struct gfs2_glock *gl = ip->i_gl;
 
-	truncate_inode_pages(gfs2_glock2aspace(ip->i_gl), 0);
+	if (unlikely(!gl)) {
+		/* This can only happen during incomplete inode creation. */
+		BUG_ON(!test_bit(GIF_ALLOC_FAILED, &ip->i_flags));
+		return;
+	}
+
+	truncate_inode_pages(gfs2_glock2aspace(gl), 0);
 	truncate_inode_pages(&inode->i_data, 0);
 
 	if (atomic_read(&gl->gl_revokes) == 0) {
@@ -1218,10 +1229,8 @@ static enum dinode_demise evict_should_delete(struct inode *inode,
 	struct gfs2_sbd *sdp = sb->s_fs_info;
 	int ret;
 
-	if (test_bit(GIF_ALLOC_FAILED, &ip->i_flags)) {
-		BUG_ON(!gfs2_glock_is_locked_by_me(ip->i_gl));
+	if (unlikely(test_bit(GIF_ALLOC_FAILED, &ip->i_flags)))
 		goto should_delete;
-	}
 
 	if (test_bit(GIF_DEFERRED_DELETE, &ip->i_flags))
 		return SHOULD_DEFER_EVICTION;
@@ -1298,9 +1307,11 @@ static int evict_unlinked_inode(struct inode *inode)
 	   do, gfs2_create_inode can create another inode at the same block
 	   location and try to set gl_object again. We clear gl_object here so
 	   that subsequent inode creates don't see an old gl_object. */
-	glock_clear_object(ip->i_gl, ip);
+	if (ip->i_gl) {
+		glock_clear_object(ip->i_gl, ip);
+		gfs2_inode_remember_delete(ip->i_gl, ip->i_no_formal_ino);
+	}
 	ret = gfs2_dinode_dealloc(ip);
-	gfs2_inode_remember_delete(ip->i_gl, ip->i_no_formal_ino);
 out:
 	return ret;
 }
@@ -1367,12 +1378,7 @@ static void gfs2_evict_inode(struct inode *inode)
 	struct gfs2_holder gh;
 	int ret;
 
-	if (test_bit(GIF_FREE_VFS_INODE, &ip->i_flags)) {
-		clear_inode(inode);
-		return;
-	}
-
-	if (inode->i_nlink || sb_rdonly(sb))
+	if (inode->i_nlink || sb_rdonly(sb) || !ip->i_no_addr)
 		goto out;
 
 	gfs2_holder_mark_uninitialized(&gh);
@@ -1429,6 +1435,7 @@ static struct inode *gfs2_alloc_inode(struct super_block *sb)
 	ip = alloc_inode_sb(sb, gfs2_inode_cachep, GFP_KERNEL);
 	if (!ip)
 		return NULL;
+	ip->i_no_addr = 0;
 	ip->i_flags = 0;
 	ip->i_gl = NULL;
 	gfs2_holder_mark_uninitialized(&ip->i_iopen_gh);