[Cluster-devel] [GFS2 PATCH v3 14/14] GFS2: Rework gfs2_evict_inode to prevent collisions with openers

[Bob Peterson <rpeterso@redhat.com>]

This patch mainly changes function gfs2_evict_inode so that it takes
out glock references and sets a DELETING bit to prevent collisions
from inode and glock creations from interfering. This is necessary
to ensure a smooth transition from unlinked to deleted status for
dinodes.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/incore.h  |  1 +
 fs/gfs2/meta_io.c |  6 ++++++
 fs/gfs2/super.c   | 35 ++++++++++++++++++++++++++++-------
 3 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index c8f9bb9..effa924 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -381,6 +381,7 @@ enum {
 	GIF_SW_PAGED		= 3,
 	GIF_ORDERED		= 4,
 	GIF_FREE_VFS_INODE      = 5,
+	GIF_AM_DELETING         = 6,
 };
 
 struct gfs2_inode {
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index c20d7ca..040eb15 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -128,6 +128,12 @@ struct buffer_head *gfs2_getbuf(struct gfs2_glock *gl, u64 blkno, int create)
 	index = blkno >> shift;             /* convert block to page */
 	bufnum = blkno - (index << shift);  /* block buf index within page */
 
+	if ((gl->gl_name.ln_type == LM_TYPE_INODE) && gl->gl_object) {
+		struct gfs2_inode *ip = gl->gl_object;
+		struct inode *inode = &ip->i_inode;
+		if (!test_bit(GIF_AM_DELETING, &ip->i_flags))
+			BUG_ON(inode->i_state & I_FREEING);
+	}
 	if (create) {
 		for (;;) {
 			page = grab_cache_page(mapping, index);
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 06bd72b..189389e 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1511,6 +1511,7 @@ static void gfs2_evict_inode(struct inode *inode)
 	struct gfs2_sbd *sdp = sb->s_fs_info;
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_holder gh;
+	struct gfs2_glock *io_gl = NULL;
 	struct address_space *metamapping;
 	int error;
 
@@ -1522,6 +1523,7 @@ static void gfs2_evict_inode(struct inode *inode)
 	if (inode->i_nlink || (sb->s_flags & MS_RDONLY))
 		goto out;
 
+	BUG_ON(__lockref_is_dead(&ip->i_gl->gl_lockref));
 	/* Must not read inode block until block type has been verified */
 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_SKIP, &gh);
 	if (unlikely(error)) {
@@ -1531,10 +1533,13 @@ static void gfs2_evict_inode(struct inode *inode)
 		goto out;
 	}
 
+	set_bit(GIF_AM_DELETING, &ip->i_flags);
 	if (!test_bit(GIF_ALLOC_FAILED, &ip->i_flags)) {
 		error = gfs2_check_blk_type(sdp, ip->i_no_addr, GFS2_BLKST_UNLINKED);
-		if (error)
-			goto out_truncate;
+		if (error) {
+			gfs2_glock_dq_uninit(&gh);
+			goto out;
+		}
 	}
 
 	if (test_bit(GIF_INVALID, &ip->i_flags)) {
@@ -1543,10 +1548,22 @@ static void gfs2_evict_inode(struct inode *inode)
 			goto out_truncate;
 	}
 
+	/* The iopen glock may have been released prior to this, but we need
+	   it back. */
+	error = gfs2_glock_get(sdp, ip->i_no_addr, &gfs2_iopen_glops, CREATE,
+			       &io_gl);
+	if (error)
+		goto out_truncate;
+
 	ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
-	gfs2_glock_dq_wait(&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 (ip->i_iopen_gh.gh_gl &&
+	    test_bit(HIF_HOLDER, &ip->i_iopen_gh.gh_iflags)) {
+		gfs2_glock_dq_wait(&ip->i_iopen_gh);
+		gfs2_holder_uninit(&ip->i_iopen_gh);
+	}
+
+	error = gfs2_glock_nq_init(io_gl, LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB |
+				   GL_NOCACHE, &ip->i_iopen_gh);
 	if (error)
 		goto out_truncate;
 
@@ -1598,11 +1615,15 @@ out_unlock:
 	if (gfs2_rs_active(ip->i_res))
 		gfs2_rs_deltree(ip->i_res);
 
-	if (test_bit(HIF_HOLDER, &ip->i_iopen_gh.gh_iflags)) {
+	if (ip->i_iopen_gh.gh_gl &&
+	    test_bit(HIF_HOLDER, &ip->i_iopen_gh.gh_iflags)) {
 		ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
 		gfs2_glock_dq_wait(&ip->i_iopen_gh);
+		gfs2_holder_uninit(&ip->i_iopen_gh);
 	}
-	gfs2_holder_uninit(&ip->i_iopen_gh);
+	if (io_gl)
+		gfs2_glock_put(io_gl);
+
 	gfs2_glock_dq_uninit(&gh);
 	if (error && error != GLR_TRYFAILED && error != -EROFS)
 		fs_warn(sdp, "gfs2_evict_inode: %d\n", error);
-- 
2.4.3