[Cluster-devel] [PATCH 1/4] gfs2: Fix remote demote of weak glock holders

[Cluster-devel] [PATCH 1/4] gfs2: Fix remote demote of weak glock holders

[Andreas Gruenbacher]

When we mock up a temporary holder in gfs2_glock_cb to demote weak holders in
response to a remote locking conflict, we don't set the HIF_HOLDER flag.  This
causes function may_grant to BUG.  Fix by setting the missing HIF_HOLDER flag
in the mock glock holder.

In addition, define the mock glock holder where it is used.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/gfs2/glock.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 8dbd6fe66420..44a7a4288956 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1857,7 +1857,6 @@ void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
 
 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
 {
-	struct gfs2_holder mock_gh = { .gh_gl = gl, .gh_state = state, };
 	unsigned long delay = 0;
 	unsigned long holdtime;
 	unsigned long now = jiffies;
@@ -1890,8 +1889,13 @@ void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
 	 * keep the glock until the last strong holder is done with it.
 	 */
 	if (!find_first_strong_holder(gl)) {
-		if (state == LM_ST_UNLOCKED)
-			mock_gh.gh_state = LM_ST_EXCLUSIVE;
+		struct gfs2_holder mock_gh = {
+			.gh_gl = gl,
+			.gh_state = (state == LM_ST_UNLOCKED) ?
+				    LM_ST_EXCLUSIVE : state,
+			.gh_iflags = BIT(HIF_HOLDER)
+		};
+
 		demote_incompat_holders(gl, &mock_gh);
 	}
 	handle_callback(gl, state, delay, true);
-- 
2.33.1

[Cluster-devel] [PATCH 2/4] gfs2: gfs2_inode_lookup cleanup

[Andreas Gruenbacher]

In gfs2_inode_lookup, once the inode has been looked up, we check if the
inode generation (no_formal_ino) is the one we're looking for.  If it
isn't and the inode wasn't in the inode cache, we discard the newly
looked up inode.  This is unnecessary, complicates the code, and makes
future changes to gfs2_inode_lookup harder, so change the code to retain
newly looked up inodes instead.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/gfs2/inode.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 6424b903e885..806357f0c7ee 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -208,20 +208,15 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 			gfs2_glock_dq_uninit(&i_gh);
 
 		gfs2_set_iop(inode);
+		unlock_new_inode(inode);
 	}
 
 	if (no_formal_ino && ip->i_no_formal_ino &&
 	    no_formal_ino != ip->i_no_formal_ino) {
-		error = -ESTALE;
-		if (inode->i_state & I_NEW)
-			goto fail;
 		iput(inode);
-		return ERR_PTR(error);
+		return ERR_PTR(-ESTALE);
 	}
 
-	if (inode->i_state & I_NEW)
-		unlock_new_inode(inode);
-
 	return inode;
 
 fail:
-- 
2.33.1

[Cluster-devel] [PATCH 3/4] gfs2: gfs2_inode_lookup rework

[Andreas Gruenbacher]

Rework gfs2_inode_lookup() to only set up the new inode's glocks after
verifying that the new inode is valid.

There is no need for flushing the inode glock work queue anymore now,
so remove that as well.

While at it, get rid of the useless wrapper around iget5_locked() and
its unnecessary is_bad_inode() check.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/gfs2/inode.c | 84 +++++++++++++++++++------------------------------
 1 file changed, 33 insertions(+), 51 deletions(-)

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 806357f0c7ee..d73b2933fdb8 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -40,37 +40,6 @@ static const struct inode_operations gfs2_file_iops;
 static const struct inode_operations gfs2_dir_iops;
 static const struct inode_operations gfs2_symlink_iops;
 
-static int iget_test(struct inode *inode, void *opaque)
-{
-	u64 no_addr = *(u64 *)opaque;
-
-	return GFS2_I(inode)->i_no_addr == no_addr;
-}
-
-static int iget_set(struct inode *inode, void *opaque)
-{
-	u64 no_addr = *(u64 *)opaque;
-
-	GFS2_I(inode)->i_no_addr = no_addr;
-	inode->i_ino = no_addr;
-	return 0;
-}
-
-static struct inode *gfs2_iget(struct super_block *sb, u64 no_addr)
-{
-	struct inode *inode;
-
-repeat:
-	inode = iget5_locked(sb, no_addr, iget_test, iget_set, &no_addr);
-	if (!inode)
-		return inode;
-	if (is_bad_inode(inode)) {
-		iput(inode);
-		goto repeat;
-	}
-	return inode;
-}
-
 /**
  * gfs2_set_iop - Sets inode operations
  * @inode: The inode with correct i_mode filled in
@@ -104,6 +73,22 @@ static void gfs2_set_iop(struct inode *inode)
 	}
 }
 
+static int iget_test(struct inode *inode, void *opaque)
+{
+	u64 no_addr = *(u64 *)opaque;
+
+	return GFS2_I(inode)->i_no_addr == no_addr;
+}
+
+static int iget_set(struct inode *inode, void *opaque)
+{
+	u64 no_addr = *(u64 *)opaque;
+
+	GFS2_I(inode)->i_no_addr = no_addr;
+	inode->i_ino = no_addr;
+	return 0;
+}
+
 /**
  * gfs2_inode_lookup - Lookup an inode
  * @sb: The super block
@@ -132,12 +117,11 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 {
 	struct inode *inode;
 	struct gfs2_inode *ip;
-	struct gfs2_glock *io_gl = NULL;
 	struct gfs2_holder i_gh;
 	int error;
 
 	gfs2_holder_mark_uninitialized(&i_gh);
-	inode = gfs2_iget(sb, no_addr);
+	inode = iget5_locked(sb, no_addr, iget_test, iget_set, &no_addr);
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
@@ -145,22 +129,16 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 
 	if (inode->i_state & I_NEW) {
 		struct gfs2_sbd *sdp = GFS2_SB(inode);
+		struct gfs2_glock *io_gl;
 
 		error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl);
 		if (unlikely(error))
 			goto fail;
-		flush_delayed_work(&ip->i_gl->gl_work);
-
-		error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
-		if (unlikely(error))
-			goto fail;
-		if (blktype != GFS2_BLKST_UNLINKED)
-			gfs2_cancel_delete_work(io_gl);
 
 		if (type == DT_UNKNOWN || blktype != GFS2_BLKST_FREE) {
 			/*
 			 * The GL_SKIP flag indicates to skip reading the inode
-			 * block.  We read the inode with gfs2_inode_refresh
+			 * block.  We read the inode when instantiating it
 			 * after possibly checking the block type.
 			 */
 			error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE,
@@ -181,24 +159,31 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 			}
 		}
 
-		glock_set_object(ip->i_gl, ip);
 		set_bit(GLF_INSTANTIATE_NEEDED, &ip->i_gl->gl_flags);
-		error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
+
+		error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
 		if (unlikely(error))
 			goto fail;
-		glock_set_object(ip->i_iopen_gh.gh_gl, ip);
+		if (blktype != GFS2_BLKST_UNLINKED)
+			gfs2_cancel_delete_work(io_gl);
+		error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
 		gfs2_glock_put(io_gl);
-		io_gl = NULL;
+		if (unlikely(error))
+			goto fail;
 
 		/* Lowest possible timestamp; will be overwritten in gfs2_dinode_in. */
 		inode->i_atime.tv_sec = 1LL << (8 * sizeof(inode->i_atime.tv_sec) - 1);
 		inode->i_atime.tv_nsec = 0;
 
+		glock_set_object(ip->i_gl, ip);
+
 		if (type == DT_UNKNOWN) {
 			/* Inode glock must be locked already */
 			error = gfs2_instantiate(&i_gh);
-			if (error)
+			if (error) {
+				glock_clear_object(ip->i_gl, ip);
 				goto fail;
+			}
 		} else {
 			ip->i_no_formal_ino = no_formal_ino;
 			inode->i_mode = DT2IF(type);
@@ -206,6 +191,7 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 
 		if (gfs2_holder_initialized(&i_gh))
 			gfs2_glock_dq_uninit(&i_gh);
+		glock_set_object(ip->i_iopen_gh.gh_gl, ip);
 
 		gfs2_set_iop(inode);
 		unlock_new_inode(inode);
@@ -220,12 +206,8 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 	return inode;
 
 fail:
-	if (gfs2_holder_initialized(&ip->i_iopen_gh)) {
-		glock_clear_object(ip->i_iopen_gh.gh_gl, ip);
+	if (gfs2_holder_initialized(&ip->i_iopen_gh))
 		gfs2_glock_dq_uninit(&ip->i_iopen_gh);
-	}
-	if (io_gl)
-		gfs2_glock_put(io_gl);
 	if (gfs2_holder_initialized(&i_gh))
 		gfs2_glock_dq_uninit(&i_gh);
 	iget_failed(inode);
-- 
2.33.1

[Cluster-devel] [PATCH 4/4] gfs2: gfs2_create_inode rework

[Andreas Gruenbacher]

When gfs2_lookup_by_inum() calls gfs2_inode_lookup() for an uncached
inode, gfs2_inode_lookup() will place a new tentative inode into the
inode cache before verifying that there is a valid inode at the given
address.  This can race with gfs2_create_inode() which doesn't check for
duplicates inodes.  gfs2_create_inode() will try to assign the new inode
to the corresponding inode glock, and glock_set_object() will complain
that the glock is still in use by gfs2_inode_lookup's tentative inode.

We noticed this bug after adding commit 486408d690e1 ("gfs2: Cancel
remote delete work asynchronously") which allowed delete_work_func() to
race with gfs2_create_inode(), but the same race exists for
open-by-handle.

Fix that by switching from insert_inode_hash() to
insert_inode_locked4(), which does check for duplicate inodes.  We know
we've just managed to to allocate the new inode, so an inode tentatively
created by gfs2_inode_lookup() will eventually go away and
insert_inode_locked4() will always succeed.

In addition, don't flush the inode glock work anymore (this can now only
make things worse) and clean up glock_{set,clear}_object for the inode
glock somewhat.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/gfs2/inode.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index d73b2933fdb8..89905f4f29bb 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -707,18 +707,19 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	error = gfs2_glock_get(sdp, ip->i_no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl);
 	if (error)
 		goto fail_free_inode;
-	flush_delayed_work(&ip->i_gl->gl_work);
 
 	error = gfs2_glock_get(sdp, ip->i_no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
 	if (error)
 		goto fail_free_inode;
 	gfs2_cancel_delete_work(io_gl);
 
+	error = insert_inode_locked4(inode, ip->i_no_addr, iget_test, &ip->i_no_addr);
+	BUG_ON(error);
+
 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_SKIP, ghs + 1);
 	if (error)
 		goto fail_gunlock2;
 
-	glock_set_object(ip->i_gl, ip);
 	error = gfs2_trans_begin(sdp, blocks, 0);
 	if (error)
 		goto fail_gunlock2;
@@ -734,9 +735,9 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	if (error)
 		goto fail_gunlock2;
 
+	glock_set_object(ip->i_gl, ip);
 	glock_set_object(io_gl, ip);
 	gfs2_set_iop(inode);
-	insert_inode_hash(inode);
 
 	free_vfs_inode = 0; /* After this point, the inode is no longer
 			       considered free. Any failures need to undo
@@ -778,17 +779,17 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	gfs2_glock_dq_uninit(ghs + 1);
 	gfs2_glock_put(io_gl);
 	gfs2_qa_put(dip);
+	unlock_new_inode(inode);
 	return error;
 
 fail_gunlock3:
+	glock_clear_object(ip->i_gl, ip);
 	glock_clear_object(io_gl, ip);
 	gfs2_glock_dq_uninit(&ip->i_iopen_gh);
 fail_gunlock2:
-	glock_clear_object(io_gl, ip);
 	gfs2_glock_put(io_gl);
 fail_free_inode:
 	if (ip->i_gl) {
-		glock_clear_object(ip->i_gl, ip);
 		if (free_vfs_inode) /* else evict will do the put for us */
 			gfs2_glock_put(ip->i_gl);
 	}
@@ -806,7 +807,10 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 			mark_inode_dirty(inode);
 		set_bit(free_vfs_inode ? GIF_FREE_VFS_INODE : GIF_ALLOC_FAILED,
 			&GFS2_I(inode)->i_flags);
-		iput(inode);
+		if (inode->i_state & I_NEW)
+			iget_failed(inode);
+		else
+			iput(inode);
 	}
 	if (gfs2_holder_initialized(ghs + 1))
 		gfs2_glock_dq_uninit(ghs + 1);
-- 
2.33.1