GFS2: Be extra careful about deallocating inodes

There is a potential race in the inode deallocation code if two
nodes try to deallocate the same inode at the same time. Most of
the issue is solved by the iopen locking. There is still a small
window which is not covered by the iopen lock. This patches fixes
that and also makes the deallocation code more robust in the face of
any errors in the rgrp bitmaps, or erroneous iopen callbacks from
other nodes.

This does introduce one extra disk read, but that is generally not
an issue since its the same block that must be written to later
in the deallocation process. The total disk accesses therefore stay
the same,

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 4 insertions, 32 deletions

diff --git a/fs/gfs2/export.c b/fs/gfs2/export.c
index 9200ef2..d15876e 100644
--- a/fs/gfs2/export.c
+++ b/fs/gfs2/export.c
@@ -143,17 +143,14 @@ static struct dentry *gfs2_get_parent(struct dentry *child)
 }
 
 static struct dentry *gfs2_get_dentry(struct super_block *sb,
-		struct gfs2_inum_host *inum)
+				      struct gfs2_inum_host *inum)
 {
 	struct gfs2_sbd *sdp = sb->s_fs_info;
-	struct gfs2_holder i_gh, ri_gh, rgd_gh;
-	struct gfs2_rgrpd *rgd;
+	struct gfs2_holder i_gh;
 	struct inode *inode;
 	struct dentry *dentry;
 	int error;
 
-	/* System files? */
-
 	inode = gfs2_ilookup(sb, inum->no_addr);
 	if (inode) {
 		if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
@@ -168,29 +165,11 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb,
 	if (error)
 		return ERR_PTR(error);
 
-	error = gfs2_rindex_hold(sdp, &ri_gh);
+	error = gfs2_check_blk_type(sdp, inum->no_addr, GFS2_BLKST_DINODE);
 	if (error)
 		goto fail;
 
-	error = -EINVAL;
-	rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
-	if (!rgd)
-		goto fail_rindex;
-
-	error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
-	if (error)
-		goto fail_rindex;
-
-	error = -ESTALE;
-	if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
-		goto fail_rgd;
-
-	gfs2_glock_dq_uninit(&rgd_gh);
-	gfs2_glock_dq_uninit(&ri_gh);
-
-	inode = gfs2_inode_lookup(sb, DT_UNKNOWN,
-					inum->no_addr,
-					0, 0);
+	inode = gfs2_inode_lookup(sb, DT_UNKNOWN, inum->no_addr, 0, 0);
 	if (IS_ERR(inode)) {
 		error = PTR_ERR(inode);
 		goto fail;
@@ -224,13 +203,6 @@ out_inode:
 	if (!IS_ERR(dentry))
 		dentry->d_op = &gfs2_dops;
 	return dentry;
-
-fail_rgd:
-	gfs2_glock_dq_uninit(&rgd_gh);
-
-fail_rindex:
-	gfs2_glock_dq_uninit(&ri_gh);
-
 fail:
 	gfs2_glock_dq_uninit(&i_gh);
 	return ERR_PTR(error);