From: Steven Whitehouse <swhiteho@redhat.com>
Date: Fri, 6 Nov 2009 20:24:36 +0000
Subject: [gfs2] careful unlinking inodes
Message-id: 1257539076.2685.6.camel@localhost.localdomain
O-Subject: [RHEL 5.5] Updated patch for bz #519049 (being more careful unlinking inodes)
Bugzilla: 519049
RH-Acked-by: Abhijith Das <adas@redhat.com>

This is an updated version of the previous patch which fixes an issue
relating to lock ordering in the first patch.

The patch means that we now perform an extra check before trying to
deallocate unlinked inodes, just in case there has been a race and
another node has beaten us to it.

Steve.

diff --git a/fs/gfs2/ops_export.c b/fs/gfs2/ops_export.c
index 1a5dd36..42b98b1 100644
--- a/fs/gfs2/ops_export.c
+++ b/fs/gfs2/ops_export.c
@@ -189,14 +189,11 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_obj)
 {
 	struct gfs2_sbd *sdp = sb->s_fs_info;
 	struct gfs2_inum_host *inum = inum_obj;
-	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) {
@@ -211,29 +208,11 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_obj)
 	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 (!inode)
 		goto fail;
 	if (IS_ERR(inode)) {
@@ -274,12 +253,6 @@ out_inode:
 	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);
diff --git a/fs/gfs2/ops_super.c b/fs/gfs2/ops_super.c
index 7d634a3..81e01bd 100644
--- a/fs/gfs2/ops_super.c
+++ b/fs/gfs2/ops_super.c
@@ -545,8 +545,13 @@ static void gfs2_delete_inode(struct inode *inode)
 		goto out;
 	}
 
+	error = gfs2_check_blk_type(sdp, ip->i_no_addr, GFS2_BLKST_UNLINKED);
+	if (error)
+		goto out_truncate;
+
 	gfs2_glock_dq_wait(&ip->i_iopen_gh);
-	gfs2_holder_reinit(LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | GL_NOCACHE, &ip->i_iopen_gh);
+	gfs2_holder_reinit(LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | GL_NOCACHE,
+			   &ip->i_iopen_gh);
 	error = gfs2_glock_nq(&ip->i_iopen_gh);
 	if (error)
 		goto out_truncate;
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index a7164e7..43805af 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1275,7 +1275,7 @@ void gfs2_inplace_release(struct gfs2_inode *ip)
  * Returns: The block type (GFS2_BLKST_*)
  */
 
-unsigned char gfs2_get_block_type(struct gfs2_rgrpd *rgd, u64 block)
+static unsigned char gfs2_get_block_type(struct gfs2_rgrpd *rgd, u64 block)
 {
 	struct gfs2_bitmap *bi = NULL;
 	u32 length, rgrp_block, buf_block;
@@ -1686,6 +1686,53 @@ void gfs2_free_di(struct gfs2_rgrpd *rgd, struct gfs2_inode *ip)
 }
 
 /**
+ * gfs2_check_blk_type - Check the type of a block
+ * @sdp: The superblock
+ * @no_addr: The block number to check
+ * @type: The block type we are looking for
+ *
+ * Returns: 0 if the block type matches the expected type
+ *          -ESTALE if it doesn't match
+ *          or -ve errno if something went wrong while checking
+ */
+
+int gfs2_check_blk_type(struct gfs2_sbd *sdp, u64 no_addr, unsigned int type)
+{
+	struct gfs2_rgrpd *rgd;
+	struct gfs2_holder ri_gh, rgd_gh;
+	struct gfs2_inode *ip = GFS2_I(sdp->sd_rindex);
+	int ri_locked = 0;
+	int error;
+
+	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+		error = gfs2_rindex_hold(sdp, &ri_gh);
+		if (error)
+			goto fail;
+		ri_locked = 1;
+	}
+
+	error = -EINVAL;
+	rgd = gfs2_blk2rgrpd(sdp, 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 = 0;
+	if (gfs2_get_block_type(rgd, no_addr) != type)
+		error = -ESTALE;
+
+	gfs2_glock_dq_uninit(&rgd_gh);
+fail_rindex:
+	if (ri_locked)
+		gfs2_glock_dq_uninit(&ri_gh);
+fail:
+	return error;
+}
+
+/**
  * gfs2_rlist_add - add a RG to a list of RGs
  * @sdp: the filesystem
  * @rlist: the list of resource groups
diff --git a/fs/gfs2/rgrp.h b/fs/gfs2/rgrp.h
index 5683605..83a4554 100644
--- a/fs/gfs2/rgrp.h
+++ b/fs/gfs2/rgrp.h
@@ -44,8 +44,6 @@ gfs2_inplace_reserve_i((ip), __FILE__, __LINE__)
 
 void gfs2_inplace_release(struct gfs2_inode *ip);
 
-unsigned char gfs2_get_block_type(struct gfs2_rgrpd *rgd, u64 block);
-
 u64 gfs2_alloc_data(struct gfs2_inode *ip);
 u64 gfs2_alloc_meta(struct gfs2_inode *ip);
 u64 gfs2_alloc_di(struct gfs2_inode *ip, u64 *generation);
@@ -54,6 +52,7 @@ void gfs2_free_data(struct gfs2_inode *ip, u64 bstart, u32 blen);
 void gfs2_free_meta(struct gfs2_inode *ip, u64 bstart, u32 blen);
 void gfs2_free_di(struct gfs2_rgrpd *rgd, struct gfs2_inode *ip);
 void gfs2_unlink_di(struct inode *inode);
+int gfs2_check_blk_type(struct gfs2_sbd *sdp, u64 no_addr, unsigned int type);
 
 struct gfs2_rgrp_list {
 	unsigned int rl_rgrps;