Commit 499aa1ca authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 

Pull dcache updates from Al Viro:
 "Change of locking rules for __dentry_kill(), regularized refcounting
  rules in that area, assorted cleanups and removal of weird corner
  cases (e.g. now ->d_iput() on child is always called before the parent
  might hit __dentry_kill(), etc)"

* tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (40 commits)
  dcache: remove unnecessary NULL check in dget_dlock()
  kill DCACHE_MAY_FREE
  __d_unalias() doesn't use inode argument
  d_alloc_parallel(): in-lookup hash insertion doesn't need an RCU variant
  get rid of DCACHE_GENOCIDE
  d_genocide(): move the extern into fs/internal.h
  simple_fill_super(): don't bother with d_genocide() on failure
  nsfs: use d_make_root()
  d_alloc_pseudo(): move setting ->d_op there from the (sole) caller
  kill d_instantate_anon(), fold __d_instantiate_anon() into remaining caller
  retain_dentry(): introduce a trimmed-down lockless variant
  __dentry_kill(): new locking scheme
  d_prune_aliases(): use a shrink list
  switch select_collect{,2}() to use of to_shrink_list()
  to_shrink_list(): call only if refcount is 0
  fold dentry_kill() into dput()
  don't try to cut corners in shrink_lock_dentry()
  fold the call of retain_dentry() into fast_dput()
  Call retain_dentry() with refcount 0
  dentry_kill(): don't bother with retain_dentry() on slow path
  ...
parents bf4e7080 1b6ae9f6

Documentation/filesystems/porting.rst

+34 −0
Original line number Diff line number Diff line
@@ -1091,6 +1091,40 @@ would need to do so. 


---



**mandatory**



The list of children anchored in parent dentry got turned into hlist now.

Field names got changed (->d_children/->d_sib instead of ->d_subdirs/->d_child

for anchor/entries resp.), so any affected places will be immediately caught

by compiler.



---



**mandatory**



->d_delete() instances are now called for dentries with ->d_lock held

and refcount equal to 0.  They are not permitted to drop/regain ->d_lock.

None of in-tree instances did anything of that sort.  Make sure yours do not...



---



**mandatory**



->d_prune() instances are now called without ->d_lock held on the parent.

->d_lock on dentry itself is still held; if you need per-parent exclusions (none

of the in-tree instances did), use your own spinlock.



->d_iput() and ->d_release() are called with victim dentry still in the

list of parent's children.  It is still unhashed, marked killed, etc., just not

removed from parent's ->d_children yet.



Anyone iterating through the list of children needs to be aware of the

half-killed dentries that might be seen there; taking ->d_lock on those will

see them negative, unhashed and with negative refcount, which means that most

of the in-kernel users would've done the right thing anyway without any adjustment.



---



**recommended**



Block device freezing and thawing have been moved to holder operations.

arch/powerpc/platforms/cell/spufs/inode.c

+3 −2
Original line number Diff line number Diff line
@@ -145,10 +145,11 @@ spufs_evict_inode(struct inode *inode) 


static void spufs_prune_dir(struct dentry *dir)

{

	struct dentry *dentry, *tmp;

	struct dentry *dentry;

	struct hlist_node *n;



	inode_lock(d_inode(dir));

	list_for_each_entry_safe(dentry, tmp, &dir->d_subdirs, d_child) {

	hlist_for_each_entry_safe(dentry, n, &dir->d_children, d_sib) {

		spin_lock(&dentry->d_lock);

		if (simple_positive(dentry)) {

			dget_dlock(dentry);

fs/afs/dynroot.c

+3 −2
Original line number Diff line number Diff line
@@ -373,7 +373,7 @@ int afs_dynroot_populate(struct super_block *sb) 
void afs_dynroot_depopulate(struct super_block *sb)

{

	struct afs_net *net = afs_sb2net(sb);

	struct dentry *root = sb->s_root, *subdir, *tmp;

	struct dentry *root = sb->s_root, *subdir;



	/* Prevent more subdirs from being created */

	mutex_lock(&net->proc_cells_lock);
@@ -382,10 +382,11 @@ void afs_dynroot_depopulate(struct super_block *sb) 
	mutex_unlock(&net->proc_cells_lock);



	if (root) {

		struct hlist_node *n;

		inode_lock(root->d_inode);



		/* Remove all the pins for dirs created for manually added cells */

		list_for_each_entry_safe(subdir, tmp, &root->d_subdirs, d_child) {

		hlist_for_each_entry_safe(subdir, n, &root->d_children, d_sib) {

			if (subdir->d_fsdata) {

				subdir->d_fsdata = NULL;

				dput(subdir);

fs/autofs/expire.c

+2 −5
Original line number Diff line number Diff line
@@ -73,12 +73,9 @@ static int autofs_mount_busy(struct vfsmount *mnt, 
/* p->d_lock held */

static struct dentry *positive_after(struct dentry *p, struct dentry *child)

{

	if (child)

		child = list_next_entry(child, d_child);

	else

		child = list_first_entry(&p->d_subdirs, struct dentry, d_child);

	child = child ? d_next_sibling(child) : d_first_child(p);



	list_for_each_entry_from(child, &p->d_subdirs, d_child) {

	hlist_for_each_entry_from(child, d_sib) {

		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);

		if (simple_positive(child)) {

			dget_dlock(child);

fs/ceph/dir.c

+1 −1
Original line number Diff line number Diff line
@@ -174,7 +174,7 @@ __dcache_find_get_entry(struct dentry *parent, u64 idx, 
/*

 * When possible, we try to satisfy a readdir by peeking at the

 * dcache.  We make this work by carefully ordering dentries on

 * d_child when we initially get results back from the MDS, and

 * d_children when we initially get results back from the MDS, and

 * falling back to a "normal" sync readdir if any dentries in the dir

 * are dropped.

 *