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authorLinus Torvalds <torvalds@linux-foundation.org>2024-01-11 20:11:35 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2024-01-11 20:11:35 -0800
commit499aa1ca4eb6602df38afaecb88fc14edf50cdbb (patch)
tree32ab97c0ab43eea0e313cd1f6ec0b904a689b17b
parentbf4e7080aeed29354cb156a8eb5d221ab2b6a8cc (diff)
parent1b6ae9f6e6c3e3c35aad0f11b116a81780b8aa03 (diff)
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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 ...
-rw-r--r--Documentation/filesystems/porting.rst34
-rw-r--r--arch/powerpc/platforms/cell/spufs/inode.c5
-rw-r--r--fs/afs/dynroot.c5
-rw-r--r--fs/autofs/expire.c7
-rw-r--r--fs/ceph/dir.c2
-rw-r--r--fs/ceph/mds_client.c2
-rw-r--r--fs/coda/cache.c8
-rw-r--r--fs/dcache.c650
-rw-r--r--fs/file_table.c5
-rw-r--r--fs/internal.h5
-rw-r--r--fs/libfs.c62
-rw-r--r--fs/nfsd/nfsctl.c70
-rw-r--r--fs/notify/fsnotify.c2
-rw-r--r--fs/nsfs.c7
-rw-r--r--fs/overlayfs/export.c23
-rw-r--r--fs/tracefs/inode.c33
-rw-r--r--include/linux/dcache.h162
17 files changed, 425 insertions, 657 deletions
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index c549fb2fc3ba..1be76ef117b3 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -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.
diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index 10c1320adfd0..030de2b8c145 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -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);
diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index 1f656005018e..2cd40ba601f1 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -373,7 +373,7 @@ error:
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);
diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c
index 038b3d2d9f57..39d8c84c16f4 100644
--- a/fs/autofs/expire.c
+++ b/fs/autofs/expire.c
@@ -73,12 +73,9 @@ done:
/* 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);
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 91709934c8b1..678596684596 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -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.
*
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index d95eb525519a..02ebfabfc8ee 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2128,7 +2128,7 @@ static bool drop_negative_children(struct dentry *dentry)
goto out;
spin_lock(&dentry->d_lock);
- list_for_each_entry(child, &dentry->d_subdirs, d_child) {
+ hlist_for_each_entry(child, &dentry->d_children, d_sib) {
if (d_really_is_positive(child)) {
all_negative = false;
break;
diff --git a/fs/coda/cache.c b/fs/coda/cache.c
index 3b8c4513118f..970f0022ec52 100644
--- a/fs/coda/cache.c
+++ b/fs/coda/cache.c
@@ -93,13 +93,13 @@ static void coda_flag_children(struct dentry *parent, int flag)
struct dentry *de;
spin_lock(&parent->d_lock);
- list_for_each_entry(de, &parent->d_subdirs, d_child) {
+ hlist_for_each_entry(de, &parent->d_children, d_sib) {
+ struct inode *inode = d_inode_rcu(de);
/* don't know what to do with negative dentries */
- if (d_inode(de) )
- coda_flag_inode(d_inode(de), flag);
+ if (inode)
+ coda_flag_inode(inode, flag);
}
spin_unlock(&parent->d_lock);
- return;
}
void coda_flag_inode_children(struct inode *inode, int flag)
diff --git a/fs/dcache.c b/fs/dcache.c
index df49d29ca154..b813528fb147 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -51,8 +51,8 @@
* - d_lru
* - d_count
* - d_unhashed()
- * - d_parent and d_subdirs
- * - childrens' d_child and d_parent
+ * - d_parent and d_chilren
+ * - childrens' d_sib and d_parent
* - d_u.d_alias, d_inode
*
* Ordering:
@@ -343,7 +343,7 @@ static inline void __d_set_inode_and_type(struct dentry *dentry,
dentry->d_inode = inode;
flags = READ_ONCE(dentry->d_flags);
- flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
+ flags &= ~DCACHE_ENTRY_TYPE;
flags |= type_flags;
smp_store_release(&dentry->d_flags, flags);
}
@@ -352,7 +352,7 @@ static inline void __d_clear_type_and_inode(struct dentry *dentry)
{
unsigned flags = READ_ONCE(dentry->d_flags);
- flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
+ flags &= ~DCACHE_ENTRY_TYPE;
WRITE_ONCE(dentry->d_flags, flags);
dentry->d_inode = NULL;
if (dentry->d_flags & DCACHE_LRU_LIST)
@@ -538,7 +538,7 @@ void d_drop(struct dentry *dentry)
}
EXPORT_SYMBOL(d_drop);
-static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
+static inline void dentry_unlist(struct dentry *dentry)
{
struct dentry *next;
/*
@@ -546,12 +546,12 @@ static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
* attached to the dentry tree
*/
dentry->d_flags |= DCACHE_DENTRY_KILLED;
- if (unlikely(list_empty(&dentry->d_child)))
+ if (unlikely(hlist_unhashed(&dentry->d_sib)))
return;
- __list_del_entry(&dentry->d_child);
+ __hlist_del(&dentry->d_sib);
/*
* Cursors can move around the list of children. While we'd been
- * a normal list member, it didn't matter - ->d_child.next would've
+ * a normal list member, it didn't matter - ->d_sib.next would've
* been updated. However, from now on it won't be and for the
* things like d_walk() it might end up with a nasty surprise.
* Normally d_walk() doesn't care about cursors moving around -
@@ -559,29 +559,27 @@ static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
* of its own, we get through it without ever unlocking the parent.
* There is one exception, though - if we ascend from a child that
* gets killed as soon as we unlock it, the next sibling is found
- * using the value left in its ->d_child.next. And if _that_
+ * using the value left in its ->d_sib.next. And if _that_
* pointed to a cursor, and cursor got moved (e.g. by lseek())
* before d_walk() regains parent->d_lock, we'll end up skipping
* everything the cursor had been moved past.
*
- * Solution: make sure that the pointer left behind in ->d_child.next
+ * Solution: make sure that the pointer left behind in ->d_sib.next
* points to something that won't be moving around. I.e. skip the
* cursors.
*/
- while (dentry->d_child.next != &parent->d_subdirs) {
- next = list_entry(dentry->d_child.next, struct dentry, d_child);
+ while (dentry->d_sib.next) {
+ next = hlist_entry(dentry->d_sib.next, struct dentry, d_sib);
if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR)))
break;
- dentry->d_child.next = next->d_child.next;
+ dentry->d_sib.next = next->d_sib.next;
}
}
-static void __dentry_kill(struct dentry *dentry)
+static struct dentry *__dentry_kill(struct dentry *dentry)
{
struct dentry *parent = NULL;
bool can_free = true;
- if (!IS_ROOT(dentry))
- parent = dentry->d_parent;
/*
* The dentry is now unrecoverably dead to the world.
@@ -601,9 +599,6 @@ static void __dentry_kill(struct dentry *dentry)
}
/* if it was on the hash then remove it */
__d_drop(dentry);
- dentry_unlist(dentry, parent);
- if (parent)
- spin_unlock(&parent->d_lock);
if (dentry->d_inode)
dentry_unlink_inode(dentry);
else
@@ -612,80 +607,114 @@ static void __dentry_kill(struct dentry *dentry)
if (dentry->d_op && dentry->d_op->d_release)
dentry->d_op->d_release(dentry);
- spin_lock(&dentry->d_lock);
- if (dentry->d_flags & DCACHE_SHRINK_LIST) {
- dentry->d_flags |= DCACHE_MAY_FREE;
- can_free = false;
+ cond_resched();
+ /* now that it's negative, ->d_parent is stable */
+ if (!IS_ROOT(dentry)) {
+ parent = dentry->d_parent;
+ spin_lock(&parent->d_lock);
}
+ spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+ dentry_unlist(dentry);
+ if (dentry->d_flags & DCACHE_SHRINK_LIST)
+ can_free = false;
spin_unlock(&dentry->d_lock);
if (likely(can_free))
dentry_free(dentry);
- cond_resched();
-}
-
-static struct dentry *__lock_parent(struct dentry *dentry)
-{
- struct dentry *parent;
- rcu_read_lock();
- spin_unlock(&dentry->d_lock);
-again:
- parent = READ_ONCE(dentry->d_parent);
- spin_lock(&parent->d_lock);
- /*
- * We can't blindly lock dentry until we are sure
- * that we won't violate the locking order.
- * Any changes of dentry->d_parent must have
- * been done with parent->d_lock held, so
- * spin_lock() above is enough of a barrier
- * for checking if it's still our child.
- */
- if (unlikely(parent != dentry->d_parent)) {
+ if (parent && --parent->d_lockref.count) {
spin_unlock(&parent->d_lock);
- goto again;
+ return NULL;
}
- rcu_read_unlock();
- if (parent != dentry)
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- else
- parent = NULL;
return parent;
}
-static inline struct dentry *lock_parent(struct dentry *dentry)
+/*
+ * Lock a dentry for feeding it to __dentry_kill().
+ * Called under rcu_read_lock() and dentry->d_lock; the former
+ * guarantees that nothing we access will be freed under us.
+ * Note that dentry is *not* protected from concurrent dentry_kill(),
+ * d_delete(), etc.
+ *
+ * Return false if dentry is busy. Otherwise, return true and have
+ * that dentry's inode locked.
+ */
+
+static bool lock_for_kill(struct dentry *dentry)
{
- struct dentry *parent = dentry->d_parent;
- if (IS_ROOT(dentry))
- return NULL;
- if (likely(spin_trylock(&parent->d_lock)))
- return parent;
- return __lock_parent(dentry);
+ struct inode *inode = dentry->d_inode;
+
+ if (unlikely(dentry->d_lockref.count))
+ return false;
+
+ if (!inode || likely(spin_trylock(&inode->i_lock)))
+ return true;
+
+ do {
+ spin_unlock(&dentry->d_lock);
+ spin_lock(&inode->i_lock);
+ spin_lock(&dentry->d_lock);
+ if (likely(inode == dentry->d_inode))
+ break;
+ spin_unlock(&inode->i_lock);
+ inode = dentry->d_inode;
+ } while (inode);
+ if (likely(!dentry->d_lockref.count))
+ return true;
+ if (inode)
+ spin_unlock(&inode->i_lock);
+ return false;
}
-static inline bool retain_dentry(struct dentry *dentry)
+/*
+ * Decide if dentry is worth retaining. Usually this is called with dentry
+ * locked; if not locked, we are more limited and might not be able to tell
+ * without a lock. False in this case means "punt to locked path and recheck".
+ *
+ * In case we aren't locked, these predicates are not "stable". However, it is
+ * sufficient that at some point after we dropped the reference the dentry was
+ * hashed and the flags had the proper value. Other dentry users may have
+ * re-gotten a reference to the dentry and change that, but our work is done -
+ * we can leave the dentry around with a zero refcount.
+ */
+static inline bool retain_dentry(struct dentry *dentry, bool locked)
{
- WARN_ON(d_in_lookup(dentry));
+ unsigned int d_flags;
- /* Unreachable? Get rid of it */
+ smp_rmb();
+ d_flags = READ_ONCE(dentry->d_flags);
+
+ // Unreachable? Nobody would be able to look it up, no point retaining
if (unlikely(d_unhashed(dentry)))
return false;
- if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
+ // Same if it's disconnected
+ if (unlikely(d_flags & DCACHE_DISCONNECTED))
return false;
- if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
- if (dentry->d_op->d_delete(dentry))
+ // ->d_delete() might tell us not to bother, but that requires
+ // ->d_lock; can't decide without it
+ if (unlikely(d_flags & DCACHE_OP_DELETE)) {
+ if (!locked || dentry->d_op->d_delete(dentry))
return false;
}
- if (unlikely(dentry->d_flags & DCACHE_DONTCACHE))
+ // Explicitly told not to bother
+ if (unlikely(d_flags & DCACHE_DONTCACHE))
return false;
- /* retain; LRU fodder */
- dentry->d_lockref.count--;
- if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
+ // At this point it looks like we ought to keep it. We also might
+ // need to do something - put it on LRU if it wasn't there already
+ // and mark it referenced if it was on LRU, but not marked yet.
+ // Unfortunately, both actions require ->d_lock, so in lockless
+ // case we'd have to punt rather than doing those.
+ if (unlikely(!(d_flags & DCACHE_LRU_LIST))) {
+ if (!locked)
+ return false;
d_lru_add(dentry);
- else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
+ } else if (unlikely(!(d_flags & DCACHE_REFERENCED))) {
+ if (!locked)
+ return false;
dentry->d_flags |= DCACHE_REFERENCED;
+ }
return true;
}
@@ -705,60 +734,11 @@ void d_mark_dontcache(struct inode *inode)
EXPORT_SYMBOL(d_mark_dontcache);
/*
- * Finish off a dentry we've decided to kill.
- * dentry->d_lock must be held, returns with it unlocked.
- * Returns dentry requiring refcount drop, or NULL if we're done.
- */
-static struct dentry *dentry_kill(struct dentry *dentry)
- __releases(dentry->d_lock)
-{
- struct inode *inode = dentry->d_inode;
- struct dentry *parent = NULL;
-
- if (inode && unlikely(!spin_trylock(&inode->i_lock)))
- goto slow_positive;
-
- if (!IS_ROOT(dentry)) {
- parent = dentry->d_parent;
- if (unlikely(!spin_trylock(&parent->d_lock))) {
- parent = __lock_parent(dentry);
- if (likely(inode || !dentry->d_inode))
- goto got_locks;
- /* negative that became positive */
- if (parent)
- spin_unlock(&parent->d_lock);
- inode = dentry->d_inode;
- goto slow_positive;
- }
- }
- __dentry_kill(dentry);
- return parent;
-
-slow_positive:
- spin_unlock(&dentry->d_lock);
- spin_lock(&inode->i_lock);
- spin_lock(&dentry->d_lock);
- parent = lock_parent(dentry);
-got_locks:
- if (unlikely(dentry->d_lockref.count != 1)) {
- dentry->d_lockref.count--;
- } else if (likely(!retain_dentry(dentry))) {
- __dentry_kill(dentry);
- return parent;
- }
- /* we are keeping it, after all */
- if (inode)
- spin_unlock(&inode->i_lock);
- if (parent)
- spin_unlock(&parent->d_lock);
- spin_unlock(&dentry->d_lock);
- return NULL;
-}
-
-/*
* Try to do a lockless dput(), and return whether that was successful.
*
* If unsuccessful, we return false, having already taken the dentry lock.
+ * In that case refcount is guaranteed to be zero and we have already
+ * decided that it's not worth keeping around.
*
* The caller needs to hold the RCU read lock, so that the dentry is
* guaranteed to stay around even if the refcount goes down to zero!
@@ -766,18 +746,9 @@ got_locks:
static inline bool fast_dput(struct dentry *dentry)
{
int ret;
- unsigned int d_flags;
-
- /*
- * If we have a d_op->d_delete() operation, we sould not
- * let the dentry count go to zero, so use "put_or_lock".
- */
- if (unlikely(dentry->d_flags & DCACHE_OP_DELETE))
- return lockref_put_or_lock(&dentry->d_lockref);
/*
- * .. otherwise, we can try to just decrement the
- * lockref optimistically.
+ * try to decrement the lockref optimistically.
*/
ret = lockref_put_return(&dentry->d_lockref);
@@ -788,12 +759,12 @@ static inline bool fast_dput(struct dentry *dentry)
*/
if (unlikely(ret < 0)) {
spin_lock(&dentry->d_lock);
- if (dentry->d_lockref.count > 1) {
- dentry->d_lockref.count--;
+ if (WARN_ON_ONCE(dentry->d_lockref.count <= 0)) {
spin_unlock(&dentry->d_lock);
return true;
}
- return false;
+ dentry->d_lockref.count--;
+ goto locked;
}
/*
@@ -803,45 +774,18 @@ static inline bool fast_dput(struct dentry *dentry)
return true;
/*
- * Careful, careful. The reference count went down
- * to zero, but we don't hold the dentry lock, so
- * somebody else could get it again, and do another
- * dput(), and we need to not race with that.
- *
- * However, there is a very special and common case
- * where we don't care, because there is nothing to
- * do: the dentry is still hashed, it does not have
- * a 'delete' op, and it's referenced and already on
- * the LRU list.
- *
- * NOTE! Since we aren't locked, these values are
- * not "stable". However, it is sufficient that at
- * some point after we dropped the reference the
- * dentry was hashed and the flags had the proper
- * value. Other dentry users may have re-gotten
- * a reference to the dentry and change that, but
- * our work is done - we can leave the dentry
- * around with a zero refcount.
- *
- * Nevertheless, there are two cases that we should kill
- * the dentry anyway.
- * 1. free disconnected dentries as soon as their refcount
- * reached zero.
- * 2. free dentries if they should not be cached.
+ * Can we decide that decrement of refcount is all we needed without
+ * taking the lock? There's a very common case when it's all we need -
+ * dentry looks like it ought to be retained and there's nothing else
+ * to do.
*/
- smp_rmb();
- d_flags = READ_ONCE(dentry->d_flags);
- d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST |
- DCACHE_DISCONNECTED | DCACHE_DONTCACHE;
-
- /* Nothing to do? Dropping the reference was all we needed? */
- if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))
+ if (retain_dentry(dentry, false))
return true;
/*
- * Not the fast normal case? Get the lock. We've already decremented
- * the refcount, but we'll need to re-check the situation after
- * getting the lock.
+ * Either not worth retaining or we can't tell without the lock.
+ * Get the lock, then. We've already decremented the refcount to 0,
+ * but we'll need to re-check the situation after getting the lock.
*/
spin_lock(&dentry->d_lock);
@@ -851,17 +795,11 @@ static inline bool fast_dput(struct dentry *dentry)
* else could have killed it and marked it dead. Either way, we
* don't need to do anything else.
*/
- if (dentry->d_lockref.count) {
+locked:
+ if (dentry->d_lockref.count || retain_dentry(dentry, true)) {
spin_unlock(&dentry->d_lock);
return true;
}
-
- /*
- * Re-get the reference we optimistically dropped. We hold the
- * lock, and we just tested that it was zero, so we can just
- * set it to 1.
- */
- dentry->d_lockref.count = 1;
return false;
}
@@ -894,39 +832,37 @@ static inline bool fast_dput(struct dentry *dentry)
*/
void dput(struct dentry *dentry)
{
- while (dentry) {
- might_sleep();
-
- rcu_read_lock();
- if (likely(fast_dput(dentry))) {
- rcu_read_unlock();
- return;
- }
-
- /* Slow case: now with the dentry lock held */
+ if (!dentry)
+ return;
+ might_sleep();
+ rcu_read_lock();
+ if (likely(fast_dput(dentry))) {
rcu_read_unlock();
-
- if (likely(retain_dentry(dentry))) {
+ return;
+ }
+ while (lock_for_kill(dentry)) {
+ rcu_read_unlock();
+ dentry = __dentry_kill(dentry);
+ if (!dentry)
+ return;
+ if (retain_dentry(dentry, true)) {
spin_unlock(&dentry->d_lock);
return;
}
-
- dentry = dentry_kill(dentry);
+ rcu_read_lock();
}
+ rcu_read_unlock();
+ spin_unlock(&dentry->d_lock);
}
EXPORT_SYMBOL(dput);
-static void __dput_to_list(struct dentry *dentry, struct list_head *list)
+static void to_shrink_list(struct dentry *dentry, struct list_head *list)
__must_hold(&dentry->d_lock)
{
- if (dentry->d_flags & DCACHE_SHRINK_LIST) {
- /* let the owner of the list it's on deal with it */
- --dentry->d_lockref.count;
- } else {
+ if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
if (dentry->d_flags & DCACHE_LRU_LIST)
d_lru_del(dentry);
- if (!--dentry->d_lockref.count)
- d_shrink_add(dentry, list);
+ d_shrink_add(dentry, list);
}
}
@@ -938,22 +874,10 @@ void dput_to_list(struct dentry *dentry, struct list_head *list)
return;
}
rcu_read_unlock();
- if (!retain_dentry(dentry))
- __dput_to_list(dentry, list);
+ to_shrink_list(dentry, list);
spin_unlock(&dentry->d_lock);
}
-/* This must be called with d_lock held */
-static inline void __dget_dlock(struct dentry *dentry)
-{
- dentry->d_lockref.count++;
-}
-
-static inline void __dget(struct dentry *dentry)
-{
- lockref_get(&dentry->d_lockref);
-}
-
struct dentry *dget_parent(struct dentry *dentry)
{
int gotref;
@@ -1003,7 +927,7 @@ static struct dentry * __d_find_any_alias(struct inode *inode)
if (hlist_empty(&inode->i_dentry))
return NULL;
alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
- __dget(alias);
+ lockref_get(&alias->d_lockref);
return alias;
}
@@ -1035,7 +959,7 @@ static struct dentry *__d_find_alias(struct inode *inode)
hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
spin_lock(&alias->d_lock);
if (!d_unhashed(alias)) {
- __dget_dlock(alias);
+ dget_dlock(alias);
spin_unlock(&alias->d_lock);
return alias;
}
@@ -1102,104 +1026,53 @@ struct dentry *d_find_alias_rcu(struct inode *inode)
*/
void d_prune_aliases(struct inode *inode)
{
+ LIST_HEAD(dispose);
struct dentry *dentry;
-restart:
+
spin_lock(&inode->i_lock);
hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
spin_lock(&dentry->d_lock);
- if (!dentry->d_lockref.count) {
- struct dentry *parent = lock_parent(dentry);
- if (likely(!dentry->d_lockref.count)) {
- __dentry_kill(dentry);
- dput(parent);
- goto restart;
- }
- if (parent)
- spin_unlock(&parent->d_lock);
- }
+ if (!dentry->d_lockref.count)
+ to_shrink_list(dentry, &dispose);
spin_unlock(&dentry->d_lock);
}
spin_unlock(&inode->i_lock);
+ shrink_dentry_list(&dispose);
}
EXPORT_SYMBOL(d_prune_aliases);
-/*
- * Lock a dentry from shrink list.
- * Called under rcu_read_lock() and dentry->d_lock; the former
- * guarantees that nothing we access will be freed under us.
- * Note that dentry is *not* protected from concurrent dentry_kill(),
- * d_delete(), etc.
- *
- * Return false if dentry has been disrupted or grabbed, leaving
- * the caller to kick it off-list. Otherwise, return true and have
- * that dentry's inode and parent both locked.
- */
-static bool shrink_lock_dentry(struct dentry *dentry)
+static inline void shrink_kill(struct dentry *victim)
{
- struct inode *inode;
- struct dentry *parent;
-
- if (dentry->d_lockref.count)
- return false;
-
- inode = dentry->d_inode;
- if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
- spin_unlock(&dentry->d_lock);
- spin_lock(&inode->i_lock);
- spin_lock(&dentry->d_lock);
- if (unlikely(dentry->d_lockref.count))
- goto out;
- /* changed inode means that somebody had grabbed it */
- if (unlikely(inode != dentry->d_inode))
- goto out;
- }
-
- parent = dentry->d_parent;
- if (IS_ROOT(dentry) || likely(spin_trylock(&parent->d_lock)))
- return true;
-
- spin_unlock(&dentry->d_lock);
- spin_lock(&parent->d_lock);
- if (unlikely(parent != dentry->d_parent)) {
- spin_unlock(&parent->d_lock);
- spin_lock(&dentry->d_lock);
- goto out;
- }
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- if (likely(!dentry->d_lockref.count))
- return true;
- spin_unlock(&parent->d_lock);
-out:
- if (inode)
- spin_unlock(&inode->i_lock);
- return false;
+ do {
+ rcu_read_unlock();
+ victim = __dentry_kill(victim);
+ rcu_read_lock();
+ } while (victim && lock_for_kill(victim));
+ rcu_read_unlock();
+ if (victim)
+ spin_unlock(&victim->d_lock);
}
void shrink_dentry_list(struct list_head *list)
{
while (!list_empty(list)) {
- struct dentry *dentry, *parent;
+ struct dentry *dentry;
dentry = list_entry(list->prev, struct dentry, d_lru);
spin_lock(&dentry->d_lock);
rcu_read_lock();
- if (!shrink_lock_dentry(dentry)) {
- bool can_free = false;
+ if (!lock_for_kill(dentry)) {
+ bool can_free;
rcu_read_unlock();
d_shrink_del(dentry);
- if (dentry->d_lockref.count < 0)
- can_free = dentry->d_flags & DCACHE_MAY_FREE;
+ can_free = dentry->d_flags & DCACHE_DENTRY_KILLED;
spin_unlock(&dentry->d_lock);
if (can_free)
dentry_free(dentry);
continue;
}
- rcu_read_unlock();
d_shrink_del(dentry);
- parent = dentry->d_parent;
- if (parent != dentry)
- __dput_to_list(parent, list);
- __dentry_kill(dentry);
+ shrink_kill(dentry);
}
}
@@ -1349,8 +1222,7 @@ enum d_walk_ret {
static void d_walk(struct dentry *parent, void *data,
enum d_walk_ret (*enter)(void *, struct dentry *))
{
- struct dentry *this_parent;
- struct list_head *next;
+ struct dentry *this_parent, *dentry;
unsigned seq = 0;
enum d_walk_ret ret;
bool retry = true;
@@ -1372,13 +1244,9 @@ again:
break;
}
repeat:
- next = this_parent->d_subdirs.next;
+ dentry = d_first_child(this_parent);
resume:
- while (next != &this_parent->d_subdirs) {
- struct list_head *tmp = next;
- struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
- next = tmp->next;
-
+ hlist_for_each_entry_from(dentry, d_sib) {
if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR))
continue;
@@ -1399,7 +1267,7 @@ resume:
continue;
}
- if (!list_empty(&dentry->d_subdirs)) {
+ if (!hlist_empty(&dentry->d_children)) {
spin_unlock(&this_parent->d_lock);
spin_release(&dentry->d_lock.dep_map, _RET_IP_);
this_parent = dentry;
@@ -1414,24 +1282,23 @@ resume:
rcu_read_lock();
ascend:
if (this_parent != parent) {
- struct dentry *child = this_parent;
- this_parent = child->d_parent;
+ dentry = this_parent;
+ this_parent = dentry->d_parent;
- spin_unlock(&child->d_lock);
+ spin_unlock(&dentry->d_lock);
spin_lock(&this_parent->d_lock);
/* might go back up the wrong parent if we have had a rename. */
if (need_seqretry(&rename_lock, seq))
goto rename_retry;
/* go into the first sibling still alive */
- do {
- next = child->d_child.next;
- if (next == &this_parent->d_subdirs)
- goto ascend;
- child = list_entry(next, struct dentry, d_child);
- } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
- rcu_read_unlock();
- goto resume;
+ hlist_for_each_entry_continue(dentry, d_sib) {
+ if (likely(!(dentry->d_flags & DCACHE_DENTRY_KILLED))) {
+ rcu_read_unlock();
+ goto resume;
+ }
+ }
+ goto ascend;
}
if (need_seqretry(&rename_lock, seq))
goto rename_retry;
@@ -1531,7 +1398,7 @@ out:
* Search the dentry child list of the specified parent,
* and move any unused dentries to the end of the unused
* list for prune_dcache(). We descend to the next level
- * whenever the d_subdirs list is non-empty and continue
+ * whenever the d_children list is non-empty and continue
* searching.
*
* It returns zero iff there are no unused children,
@@ -1561,13 +1428,11 @@ static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
if (dentry->d_flags & DCACHE_SHRINK_LIST) {
data->found++;
- } else {
- if (dentry->d_flags & DCACHE_LRU_LIST)
- d_lru_del(dentry);
- if (!dentry->d_lockref.count) {
- d_shrink_add(dentry, &data->dispose);
- data->found++;
- }
+ } else if (!dentry->d_lockref.count) {
+ to_shrink_list(dentry, &data->dispose);
+ data->found++;
+ } else if (dentry->d_lockref.count < 0) {
+ data->found++;
}
/*
* We can return to the caller if we have found some (this
@@ -1588,17 +1453,13 @@ static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry)
if (data->start == dentry)
goto out;
- if (dentry->d_flags & DCACHE_SHRINK_LIST) {
- if (!dentry->d_lockref.count) {
+ if (!dentry->d_lockref.count) {
+ if (dentry->d_flags & DCACHE_SHRINK_LIST) {
rcu_read_lock();
data->victim = dentry;
return D_WALK_QUIT;
}
- } else {
- if (dentry->d_flags & DCACHE_LRU_LIST)
- d_lru_del(dentry);
- if (!dentry->d_lockref.count)
- d_shrink_add(dentry, &data->dispose);
+ to_shrink_list(dentry, &data->dispose);
}
/*
* We can return to the caller if we have found some (this
@@ -1636,17 +1497,12 @@ void shrink_dcache_parent(struct dentry *parent)
data.victim = NULL;
d_walk(parent, &data, select_collect2);
if (data.victim) {
- struct dentry *parent;
spin_lock(&data.victim->d_lock);
- if (!shrink_lock_dentry(data.victim)) {
+ if (!lock_for_kill(data.victim)) {
spin_unlock(&data.victim->d_lock);
rcu_read_unlock();
} else {
- rcu_read_unlock();
- parent = data.victim->d_parent;
- if (parent != data.victim)
- __dput_to_list(parent, &data.dispose);
- __dentry_kill(data.victim);
+ shrink_kill(data.victim);
}
}
if (!list_empty(&data.dispose))
@@ -1658,7 +1514,7 @@ EXPORT_SYMBOL(shrink_dcache_parent);
static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
{
/* it has busy descendents; complain about those instead */
- if (!list_empty(&dentry->d_subdirs))
+ if (!hlist_empty(&dentry->d_children))
return D_WALK_CONTINUE;
/* root with refcount 1 is fine */
@@ -1708,8 +1564,7 @@ static enum d_walk_ret find_submount(void *_data, struct dentry *dentry)
{
struct dentry **victim = _data;
if (d_mountpoint(dentry)) {
- __dget_dlock(dentry);
- *victim = dentry;
+ *victim = dget_dlock(dentry);
return D_WALK_QUIT;
}
return D_WALK_CONTINUE;
@@ -1815,9 +1670,9 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
dentry->d_fsdata = NULL;
INIT_HLIST_BL_NODE(&dentry->d_hash);
INIT_LIST_HEAD(&dentry->d_lru);
- INIT_LIST_HEAD(&dentry->d_subdirs);
+ INIT_HLIST_HEAD(&dentry->d_children);
INIT_HLIST_NODE(&dentry->d_u.d_alias);
- INIT_LIST_HEAD(&dentry->d_child);
+ INIT_HLIST_NODE(&dentry->d_sib);
d_set_d_op(dentry, dentry->d_sb->s_d_op);
if (dentry->d_op && dentry->d_op->d_init) {
@@ -1854,9 +1709,8 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
* don't need child lock because it is not subject
* to concurrency here
*/
- __dget_dlock(parent);
- dentry->d_parent = parent;
- list_add(&dentry->d_child, &parent->d_subdirs);
+ dentry->d_parent = dget_dlock(parent);
+ hlist_add_head(&dentry->d_sib, &parent->d_children);
spin_unlock(&parent->d_lock);
return dentry;
@@ -1896,9 +1750,15 @@ struct dentry *d_alloc_cursor(struct dentry * parent)
*/
struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
{
+ static const struct dentry_operations anon_ops = {
+ .d_dname = simple_dname
+ };
struct dentry *dentry = __d_alloc(sb, name);
- if (likely(dentry))
+ if (likely(dentry)) {
dentry->d_flags |= DCACHE_NORCU;
+ if (!sb->s_d_op)
+ d_set_d_op(dentry, &anon_ops);
+ }
return dentry;
}
@@ -1942,22 +1802,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
}
EXPORT_SYMBOL(d_set_d_op);
-
-/*
- * d_set_fallthru - Mark a dentry as falling through to a lower layer
- * @dentry - The dentry to mark
- *
- * Mark a dentry as falling through to the lower layer (as set with
- * d_pin_lower()). This flag may be recorded on the medium.
- */
-void d_set_fallthru(struct dentry *dentry)
-{
- spin_lock(&dentry->d_lock);
- dentry->d_flags |= DCACHE_FALLTHRU;
- spin_unlock(&dentry->d_lock);
-}
-EXPORT_SYMBOL(d_set_fallthru);
-
static unsigned d_flags_for_inode(struct inode *inode)
{
unsigned add_flags = DCACHE_REGULAR_TYPE;
@@ -2076,75 +1920,55 @@ struct dentry *d_make_root(struct inode *root_inode)
}
EXPORT_SYMBOL(d_make_root);
-static struct dentry *__d_instantiate_anon(struct dentry *dentry,
- struct inode *inode,
- bool disconnected)
-{
- struct dentry *res;
- unsigned add_flags;
-
- security_d_instantiate(dentry, inode);
- spin_lock(&inode->i_lock);
- res = __d_find_any_alias(inode);
- if (res) {
- spin_unlock(&inode->i_lock);
- dput(dentry);
- goto out_iput;
- }
-
- /* attach a disconnected dentry */
- add_flags = d_flags_for_inode(inode);
-
- if (disconnected)
- add_flags |= DCACHE_DISCONNECTED;
-
- spin_lock(&dentry->d_lock);
- __d_set_inode_and_type(dentry, inode, add_flags);
- hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
- if (!disconnected) {
- hlist_bl_lock(&dentry->d_sb->s_roots);
- hlist_bl_add_head(&dentry->d_hash, &dentry->d_sb->s_roots);
- hlist_bl_unlock(&dentry->d_sb->s_roots);
- }
- spin_unlock(&dentry->d_lock);
- spin_unlock(&inode->i_lock);
-
- return dentry;
-
- out_iput:
- iput(inode);
- return res;
-}
-
-struct dentry *d_instantiate_anon(struct dentry *dentry, struct inode *inode)
-{
- return __d_instantiate_anon(dentry, inode, true);
-}
-EXPORT_SYMBOL(d_instantiate_anon);
-
static struct dentry *__d_obtain_alias(struct inode *inode, bool disconnected)
{
- struct dentry *tmp;
- struct dentry *res;
+ struct super_block *sb;
+ struct dentry *new, *res;
if (!inode)
return ERR_PTR(-ESTALE);
if (IS_ERR(inode))
return ERR_CAST(inode);
- res = d_find_any_alias(inode);
+ sb = inode->i_sb;
+
+ res = d_find_any_alias(inode); /* existing alias? */
if (res)
- goto out_iput;
+ goto out;
- tmp = d_alloc_anon(inode->i_sb);
- if (!tmp) {
+ new = d_alloc_anon(sb);
+ if (!new) {
res = ERR_PTR(-ENOMEM);
- goto out_iput;
+ goto out;
}
- return __d_instantiate_anon(tmp, inode, disconnected);
+ security_d_instantiate(new, inode);
+ spin_lock(&inode->i_lock);
+ res = __d_find_any_alias(inode); /* recheck under lock */
+ if (likely(!res)) { /* still no alias, attach a disconnected dentry */
+ unsigned add_flags = d_flags_for_inode(inode);
+
+ if (disconnected)
+ add_flags |= DCACHE_DISCONNECTED;
-out_iput:
+ spin_lock(&new->d_lock);
+ __d_set_inode_and_type(new, inode, add_flags);
+ hlist_add_head(&new->d_u.d_alias, &inode->i_dentry);
+ if (!disconnected) {
+ hlist_bl_lock(&sb->s_roots);
+ hlist_bl_add_head(&new->d_hash, &sb->s_roots);
+ hlist_bl_unlock(&sb->s_roots);
+ }
+ spin_unlock(&new->d_lock);
+ spin_unlock(&inode->i_lock);
+ inode = NULL; /* consumed by new->d_inode */
+ res = new;
+ } else {
+ spin_unlock(&inode->i_lock);
+ dput(new);
+ }
+
+ out:
iput(inode);
return res;
}
@@ -2728,7 +2552,7 @@ retry:
/* we can't take ->d_lock here; it's OK, though. */
new->d_flags |= DCACHE_PAR_LOOKUP;
new->d_wait = wq;
- hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b);
+ hlist_bl_add_head(&new->d_u.d_in_lookup_hash, b);
hlist_bl_unlock(b);
return new;
mismatch:
@@ -2852,7 +2676,7 @@ struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode)
spin_unlock(&alias->d_lock);
alias = NULL;
} else {
- __dget_dlock(alias);
+ dget_dlock(alias);
__d_rehash(alias);
spin_unlock(&alias->d_lock);
}
@@ -2994,11 +2818,15 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
} else {
target->d_parent = old_parent;
swap_names(dentry, target);
- list_move(&target->d_child, &target->d_parent->d_subdirs);
+ if (!hlist_unhashed(&target->d_sib))
+ __hlist_del(&target->d_sib);
+ hlist_add_head(&target->d_sib, &target->d_parent->d_children);
__d_rehash(target);
fsnotify_update_flags(target);
}
- list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
+ if (!hlist_unhashed(&dentry->d_sib))
+ __hlist_del(&dentry->d_sib);
+ hlist_add_head(&dentry->d_sib, &dentry->d_parent->d_children);
__d_rehash(dentry);
fsnotify_update_flags(dentry);
fscrypt_handle_d_move(dentry);
@@ -3081,8 +2909,7 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
* Note: If ever the locking in lock_rename() changes, then please
* remember to update this too...
*/
-static int __d_unalias(struct inode *inode,
- struct dentry *dentry, struct dentry *alias)
+static int __d_unalias(struct dentry *dentry, struct dentry *alias)
{
struct mutex *m1 = NULL;
struct rw_semaphore *m2 = NULL;
@@ -3163,7 +2990,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
inode->i_sb->s_id);
} else if (!IS_ROOT(new)) {
struct dentry *old_parent = dget(new->d_parent);
- int err = __d_unalias(inode, dentry, new);
+ int err = __d_unalias(dentry, new);
write_sequnlock(&rename_lock);
if (err) {
dput(new);
@@ -3234,10 +3061,7 @@ static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
if (d_unhashed(dentry) || !dentry->d_inode)
return D_WALK_SKIP;
- if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
- dentry->d_flags |= DCACHE_GENOCIDE;
- dentry->d_lockref.count--;
- }
+ dentry->d_lockref.count--;
}
return D_WALK_CONTINUE;
}
diff --git a/fs/file_table.c b/fs/file_table.c
index c5ac2cc05135..b991f90571b4 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -316,9 +316,6 @@ struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt,
const char *name, int flags,
const struct file_operations *fops)
{
- static const struct dentry_operations anon_ops = {
- .d_dname = simple_dname
- };
struct qstr this = QSTR_INIT(name, strlen(name));
struct path path;
struct file *file;
@@ -326,8 +323,6 @@ struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt,
path.dentry = d_alloc_pseudo(mnt->mnt_sb, &this);
if (!path.dentry)
return ERR_PTR(-ENOMEM);
- if (!mnt->mnt_sb->s_d_op)
- d_set_d_op(path.dentry, &anon_ops);
path.mnt = mntget(mnt);
d_instantiate(path.dentry, inode);
file = alloc_file(&path, flags, fops);
diff --git a/fs/internal.h b/fs/internal.h
index 93cdeeb858cb..b67406435fc0 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -214,6 +214,11 @@ extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *)
extern char *simple_dname(struct dentry *, char *, int);
extern void dput_to_list(struct dentry *, struct list_head *);
extern void shrink_dentry_list(struct list_head *);
+extern void shrink_dcache_for_umount(struct super_block *);
+extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
+extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
+ const struct qstr *name, unsigned *seq);
+extern void d_genocide(struct dentry *);
/*
* pipe.c
diff --git a/fs/libfs.c b/fs/libfs.c
index c2aa6fd4795c..eec6031b0155 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -104,15 +104,16 @@ EXPORT_SYMBOL(dcache_dir_close);
* If no such element exists, NULL is returned.
*/
static struct dentry *scan_positives(struct dentry *cursor,
- struct list_head *p,
+ struct hlist_node **p,
loff_t count,
struct dentry *last)
{
struct dentry *dentry = cursor->d_parent, *found = NULL;
spin_lock(&dentry->d_lock);
- while ((p = p->next) != &dentry->d_subdirs) {
- struct dentry *d = list_entry(p, struct dentry, d_child);
+ while (*p) {
+ struct dentry *d = hlist_entry(*p, struct dentry, d_sib);
+ p = &d->d_sib.next;
// we must at least skip cursors, to avoid livelocks
if (d->d_flags & DCACHE_DENTRY_CURSOR)
continue;
@@ -126,8 +127,10 @@ static struct dentry *scan_positives(struct dentry *cursor,
count = 1;
}
if (need_resched()) {
- list_move(&cursor->d_child, p);
- p = &cursor->d_child;
+ if (!hlist_unhashed(&cursor->d_sib))
+ __hlist_del(&cursor->d_sib);
+ hlist_add_behind(&cursor->d_sib, &d->d_sib);
+ p = &cursor->d_sib.next;
spin_unlock(&dentry->d_lock);
cond_resched();
spin_lock(&dentry->d_lock);
@@ -159,13 +162,12 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
inode_lock_shared(dentry->d_inode);
if (offset > 2)
- to = scan_positives(cursor, &dentry->d_subdirs,
+ to = scan_positives(cursor, &dentry->d_children.first,
offset - 2, NULL);
spin_lock(&dentry->d_lock);
+ hlist_del_init(&cursor->d_sib);
if (to)
- list_move(&cursor->d_child, &to->d_child);
- else
- list_del_init(&cursor->d_child);
+ hlist_add_behind(&cursor->d_sib, &to->d_sib);
spin_unlock(&dentry->d_lock);
dput(to);
@@ -187,19 +189,16 @@ int dcache_readdir(struct file *file, struct dir_context *ctx)
{
struct dentry *dentry = file->f_path.dentry;
struct dentry *cursor = file->private_data;
- struct list_head *anchor = &dentry->d_subdirs;
struct dentry *next = NULL;
- struct list_head *p;
+ struct hlist_node **p;
if (!dir_emit_dots(file, ctx))
return 0;
if (ctx->pos == 2)
- p = anchor;
- else if (!list_empty(&cursor->d_child))
- p = &cursor->d_child;
+ p = &dentry->d_children.first;
else
- return 0;
+ p = &cursor->d_sib.next;
while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
@@ -207,13 +206,12 @@ int dcache_readdir(struct file *file, struct dir_context *ctx)
fs_umode_to_dtype(d_inode(next)->i_mode)))
break;
ctx->pos++;
- p = &next->d_child;
+ p = &next->d_sib.next;
}
spin_lock(&dentry->d_lock);
+ hlist_del_init(&cursor->d_sib);
if (next)
- list_move_tail(&cursor->d_child, &next->d_child);
- else
- list_del_init(&cursor->d_child);
+ hlist_add_before(&cursor->d_sib, &next->d_sib);
spin_unlock(&dentry->d_lock);
dput(next);
@@ -500,12 +498,11 @@ const struct file_operations simple_offset_dir_operations = {
static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
{
- struct dentry *child = NULL;
- struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
+ struct dentry *child = NULL, *d;
spin_lock(&parent->d_lock);
- while ((p = p->next) != &parent->d_subdirs) {
- struct dentry *d = container_of(p, struct dentry, d_child);
+ d = prev ? d_next_sibling(prev) : d_first_child(parent);
+ hlist_for_each_entry_from(d, d_sib) {
if (simple_positive(d)) {
spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
if (simple_positive(d))
@@ -666,7 +663,7 @@ int simple_empty(struct dentry *dentry)
int ret = 0;
spin_lock(&dentry->d_lock);
- list_for_each_entry(child, &dentry->d_subdirs, d_child) {
+ hlist_for_each_entry(child, &dentry->d_children, d_sib) {
spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
if (simple_positive(child)) {
spin_unlock(&child->d_lock);
@@ -920,7 +917,6 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
const struct tree_descr *files)
{
struct inode *inode;
- struct dentry *root;
struct dentry *dentry;
int i;
@@ -943,8 +939,8 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
set_nlink(inode, 2);
- root = d_make_root(inode);
- if (!root)
+ s->s_root = d_make_root(inode);
+ if (!s->s_root)
return -ENOMEM;
for (i = 0; !files->name || files->name[0]; i++, files++) {
if (!files->name)
@@ -956,13 +952,13 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
"with an index of 1!\n", __func__,
s->s_type->name);
- dentry = d_alloc_name(root, files->name);
+ dentry = d_alloc_name(s->s_root, files->name);
if (!dentry)
- goto out;
+ return -ENOMEM;
inode = new_inode(s);
if (!inode) {
dput(dentry);
- goto out;
+ return -ENOMEM;
}
inode->i_mode = S_IFREG | files->mode;
simple_inode_init_ts(inode);
@@ -970,13 +966,7 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
inode->i_ino = i;
d_add(dentry, inode);
}
- s->s_root = root;
return 0;
-out:
- d_genocide(root);
- shrink_dcache_parent(root);
- dput(root);
- return -ENOMEM;
}
EXPORT_SYMBOL(simple_fill_super);
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 8e6dbe9e0b65..c9f9590f056b 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1242,63 +1242,34 @@ static inline void _nfsd_symlink(struct dentry *parent, const char *name,
#endif
-static void clear_ncl(struct inode *inode)
+static void clear_ncl(struct dentry *dentry)
{
+ struct inode *inode = d_inode(dentry);
struct nfsdfs_client *ncl = inode->i_private;
+ spin_lock(&inode->i_lock);
inode->i_private = NULL;
+ spin_unlock(&inode->i_lock);
kref_put(&ncl->cl_ref, ncl->cl_release);
}
-static struct nfsdfs_client *__get_nfsdfs_client(struct inode *inode)
-{
- struct nfsdfs_client *nc = inode->i_private;
-
- if (nc)
- kref_get(&nc->cl_ref);
- return nc;
-}
-
struct nfsdfs_client *get_nfsdfs_client(struct inode *inode)
{
struct nfsdfs_client *nc;
- inode_lock_shared(inode);
- nc = __get_nfsdfs_client(inode);
- inode_unlock_shared(inode);
+ spin_lock(&inode->i_lock);
+ nc = inode->i_private;
+ if (nc)
+ kref_get(&nc->cl_ref);
+ spin_unlock(&inode->i_lock);
return nc;
}
-/* from __rpc_unlink */
-static void nfsdfs_remove_file(struct inode *dir, struct dentry *dentry)
-{
- int ret;
-
- clear_ncl(d_inode(dentry));
- dget(dentry);
- ret = simple_unlink(dir, dentry);
- d_drop(dentry);
- fsnotify_unlink(dir, dentry);
- dput(dentry);
- WARN_ON_ONCE(ret);
-}
-
-static void nfsdfs_remove_files(struct dentry *root)
-{
- struct dentry *dentry, *tmp;
-
- list_for_each_entry_safe(dentry, tmp, &root->d_subdirs, d_child) {
- if (!simple_positive(dentry)) {
- WARN_ON_ONCE(1); /* I think this can't happen? */
- continue;
- }
- nfsdfs_remove_file(d_inode(root), dentry);
- }
-}
/* XXX: cut'n'paste from simple_fill_super; figure out if we could share
* code instead. */
static int nfsdfs_create_files(struct dentry *root,
const struct tree_descr *files,
+ struct nfsdfs_client *ncl,
struct dentry **fdentries)
{
struct inode *dir = d_inode(root);
@@ -1317,8 +1288,9 @@ static int nfsdfs_create_files(struct dentry *root,
dput(dentry);
goto out;
}
+ kref_get(&ncl->cl_ref);
inode->i_fop = files->ops;
- inode->i_private = __get_nfsdfs_client(dir);
+ inode->i_private = ncl;
d_add(dentry, inode);
fsnotify_create(dir, dentry);
if (fdentries)
@@ -1327,7 +1299,6 @@ static int nfsdfs_create_files(struct dentry *root,
inode_unlock(dir);
return 0;
out:
- nfsdfs_remove_files(root);
inode_unlock(dir);
return -ENOMEM;
}
@@ -1347,7 +1318,7 @@ struct dentry *nfsd_client_mkdir(struct nfsd_net *nn,
dentry = nfsd_mkdir(nn->nfsd_client_dir, ncl, name);
if (IS_ERR(dentry)) /* XXX: tossing errors? */
return NULL;
- ret = nfsdfs_create_files(dentry, files, fdentries);
+ ret = nfsdfs_create_files(dentry, files, ncl, fdentries);
if (ret) {
nfsd_client_rmdir(dentry);
return NULL;
@@ -1358,20 +1329,7 @@ struct dentry *nfsd_client_mkdir(struct nfsd_net *nn,
/* Taken from __rpc_rmdir: */
void nfsd_client_rmdir(struct dentry *dentry)
{
- struct inode *dir = d_inode(dentry->d_parent);
- struct inode *inode = d_inode(dentry);
- int ret;
-
- inode_lock(dir);
- nfsdfs_remove_files(dentry);
- clear_ncl(inode);
- dget(dentry);
- ret = simple_rmdir(dir, dentry);
- WARN_ON_ONCE(ret);
- d_drop(dentry);
- fsnotify_rmdir(dir, dentry);
- dput(dentry);
- inode_unlock(dir);
+ simple_recursive_removal(dentry, clear_ncl);
}
static int nfsd_fill_super(struct super_block *sb, struct fs_context *fc)
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 7974e91ffe13..8bfd690e9f10 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -124,7 +124,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
* d_flags to indicate parental interest (their parent is the
* original inode) */
spin_lock(&alias->d_lock);
- list_for_each_entry(child, &alias->d_subdirs, d_child) {
+ hlist_for_each_entry(child, &alias->d_children, d_sib) {
if (!child->d_inode)
continue;
diff --git a/fs/nsfs.c b/fs/nsfs.c
index 9a4b228d42fa..34e1e3e36733 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -90,12 +90,9 @@ slow:
inode->i_fop = &ns_file_operations;
inode->i_private = ns;
- dentry = d_alloc_anon(mnt->mnt_sb);
- if (!dentry) {
- iput(inode);
+ dentry = d_make_root(inode); /* not the normal use, but... */
+ if (!dentry)
return -ENOMEM;
- }
- d_instantiate(dentry, inode);
dentry->d_fsdata = (void *)ns->ops;
d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);
if (d) {
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 6909c4a5da56..063409069f56 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -289,7 +289,6 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
{
struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;
struct dentry *upper = upper_alias ?: index;
- struct dentry *dentry;
struct inode *inode = NULL;
struct ovl_entry *oe;
struct ovl_inode_params oip = {
@@ -320,27 +319,7 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
if (upper)
ovl_set_flag(OVL_UPPERDATA, inode);
- dentry = d_find_any_alias(inode);
- if (dentry)
- goto out_iput;
-
- dentry = d_alloc_anon(inode->i_sb);
- if (unlikely(!dentry))
- goto nomem;
-
- if (upper_alias)
- ovl_dentry_set_upper_alias(dentry);
-
- ovl_dentry_init_reval(dentry, upper, OVL_I_E(inode));
-
- return d_instantiate_anon(dentry, inode);
-
-nomem:
- dput(dentry);
- dentry = ERR_PTR(-ENOMEM);
-out_iput:
- iput(inode);
- return dentry;
+ return d_obtain_alias(inode);
}
/* Get the upper or lower dentry in stack whose on layer @idx */
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index bc86ffdb103b..ad20e6af938d 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -199,21 +199,17 @@ static void change_gid(struct dentry *dentry, kgid_t gid)
*/
static void set_gid(struct dentry *parent, kgid_t gid)
{
- struct dentry *this_parent;
- struct list_head *next;
+ struct dentry *this_parent, *dentry;
this_parent = parent;
spin_lock(&this_parent->d_lock);
change_gid(this_parent, gid);
repeat:
- next = this_parent->d_subdirs.next;
+ dentry = d_first_child(this_parent);
resume:
- while (next != &this_parent->d_subdirs) {
+ hlist_for_each_entry_from(dentry, d_sib) {
struct tracefs_inode *ti;
- struct list_head *tmp = next;
- struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
- next = tmp->next;
/* Note, getdents() can add a cursor dentry with no inode */
if (!dentry->d_inode)
@@ -228,7 +224,7 @@ resume:
if (ti && (ti->flags & TRACEFS_EVENT_INODE))
eventfs_update_gid(dentry, gid);
- if (!list_empty(&dentry->d_subdirs)) {
+ if (!hlist_empty(&dentry->d_children)) {
spin_unlock(&this_parent->d_lock);
spin_release(&dentry->d_lock.dep_map, _RET_IP_);
this_parent = dentry;
@@ -243,21 +239,20 @@ resume:
rcu_read_lock();
ascend:
if (this_parent != parent) {
- struct dentry *child = this_parent;
- this_parent = child->d_parent;
+ dentry = this_parent;
+ this_parent = dentry->d_parent;
- spin_unlock(&child->d_lock);
+ spin_unlock(&dentry->d_lock);
spin_lock(&this_parent->d_lock);
/* go into the first sibling still alive */
- do {
- next = child->d_child.next;
- if (next == &this_parent->d_subdirs)
- goto ascend;
- child = list_entry(next, struct dentry, d_child);
- } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
- rcu_read_unlock();
- goto resume;
+ hlist_for_each_entry_continue(dentry, d_sib) {
+ if (likely(!(dentry->d_flags & DCACHE_DENTRY_KILLED))) {
+ rcu_read_unlock();
+ goto resume;
+ }
+ }
+ goto ascend;
}
rcu_read_unlock();
spin_unlock(&this_parent->d_lock);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 3da2f0545d5d..1666c387861f 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -68,12 +68,12 @@ extern const struct qstr dotdot_name;
* large memory footprint increase).
*/
#ifdef CONFIG_64BIT
-# define DNAME_INLINE_LEN 32 /* 192 bytes */
+# define DNAME_INLINE_LEN 40 /* 192 bytes */
#else
# ifdef CONFIG_SMP
-# define DNAME_INLINE_LEN 36 /* 128 bytes */
-# else
# define DNAME_INLINE_LEN 40 /* 128 bytes */
+# else
+# define DNAME_INLINE_LEN 44 /* 128 bytes */
# endif
#endif
@@ -101,8 +101,8 @@ struct dentry {
struct list_head d_lru; /* LRU list */
wait_queue_head_t *d_wait; /* in-lookup ones only */
};
- struct list_head d_child; /* child of parent list */
- struct list_head d_subdirs; /* our children */
+ struct hlist_node d_sib; /* child of parent list */
+ struct hlist_head d_children; /* our children */
/*
* d_alias and d_rcu can share memory
*/
@@ -111,7 +111,7 @@ struct dentry {
struct hlist_bl_node d_in_lookup_hash; /* only for in-lookup ones */
struct rcu_head d_rcu;
} d_u;
-} __randomize_layout;
+};
/*
* dentry->d_lock spinlock nesting subclasses:
@@ -151,13 +151,13 @@ struct dentry_operations {
*/
/* d_flags entries */
-#define DCACHE_OP_HASH 0x00000001
-#define DCACHE_OP_COMPARE 0x00000002
-#define DCACHE_OP_REVALIDATE 0x00000004
-#define DCACHE_OP_DELETE 0x00000008
-#define DCACHE_OP_PRUNE 0x00000010
+#define DCACHE_OP_HASH BIT(0)
+#define DCACHE_OP_COMPARE BIT(1)
+#define DCACHE_OP_REVALIDATE BIT(2)
+#define DCACHE_OP_DELETE BIT(3)
+#define DCACHE_OP_PRUNE BIT(4)
-#define DCACHE_DISCONNECTED 0x00000020
+#define DCACHE_DISCONNECTED BIT(5)
/* This dentry is possibly not currently connected to the dcache tree, in
* which case its parent will either be itself, or will have this flag as
* well. nfsd will not use a dentry with this bit set, but will first
@@ -168,50 +168,46 @@ struct dentry_operations {
* dentry into place and return that dentry rather than the passed one,
* typically using d_splice_alias. */
-#define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
+#define DCACHE_REFERENCED BIT(6) /* Recently used, don't discard. */
-#define DCACHE_DONTCACHE 0x00000080 /* Purge from memory on final dput() */
+#define DCACHE_DONTCACHE BIT(7) /* Purge from memory on final dput() */
-#define DCACHE_CANT_MOUNT 0x00000100
-#define DCACHE_GENOCIDE 0x00000200
-#define DCACHE_SHRINK_LIST 0x00000400
+#define DCACHE_CANT_MOUNT BIT(8)
+#define DCACHE_SHRINK_LIST BIT(10)
-#define DCACHE_OP_WEAK_REVALIDATE 0x00000800
+#define DCACHE_OP_WEAK_REVALIDATE BIT(11)
-#define DCACHE_NFSFS_RENAMED 0x00001000
+#define DCACHE_NFSFS_RENAMED BIT(12)
/* this dentry has been "silly renamed" and has to be deleted on the last
* dput() */
-#define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
-#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
+#define DCACHE_FSNOTIFY_PARENT_WATCHED BIT(14)
/* Parent inode is watched by some fsnotify listener */
-#define DCACHE_DENTRY_KILLED 0x00008000
+#define DCACHE_DENTRY_KILLED BIT(15)
-#define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
-#define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
-#define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
+#define DCACHE_MOUNTED BIT(16) /* is a mountpoint */
+#define DCACHE_NEED_AUTOMOUNT BIT(17) /* handle automount on this dir */
+#define DCACHE_MANAGE_TRANSIT BIT(18) /* manage transit from this dirent */
#define DCACHE_MANAGED_DENTRY \
(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
-#define DCACHE_LRU_LIST 0x00080000
+#define DCACHE_LRU_LIST BIT(19)
-#define DCACHE_ENTRY_TYPE 0x00700000
-#define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
-#define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */
-#define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */
-#define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */
-#define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */
-#define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */
-#define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */
+#define DCACHE_ENTRY_TYPE (7 << 20) /* bits 20..22 are for storing type: */
+#define DCACHE_MISS_TYPE (0 << 20) /* Negative dentry */
+#define DCACHE_WHITEOUT_TYPE (1 << 20) /* Whiteout dentry (stop pathwalk) */
+#define DCACHE_DIRECTORY_TYPE (2 << 20) /* Normal directory */
+#define DCACHE_AUTODIR_TYPE (3 << 20) /* Lookupless directory (presumed automount) */
+#define DCACHE_REGULAR_TYPE (4 << 20) /* Regular file type */
+#define DCACHE_SPECIAL_TYPE (5 << 20) /* Other file type */
+#define DCACHE_SYMLINK_TYPE (6 << 20) /* Symlink */
-#define DCACHE_MAY_FREE 0x00800000
-#define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
-#define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */
-#define DCACHE_OP_REAL 0x04000000
+#define DCACHE_NOKEY_NAME BIT(25) /* Encrypted name encoded without key */
+#define DCACHE_OP_REAL BIT(26)
-#define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
-#define DCACHE_DENTRY_CURSOR 0x20000000
-#define DCACHE_NORCU 0x40000000 /* No RCU delay for freeing */
+#define DCACHE_PAR_LOOKUP BIT(28) /* being looked up (with parent locked shared) */
+#define DCACHE_DENTRY_CURSOR BIT(29)
+#define DCACHE_NORCU BIT(30) /* No RCU delay for freeing */
extern seqlock_t rename_lock;
@@ -220,8 +216,6 @@ extern seqlock_t rename_lock;
*/
extern void d_instantiate(struct dentry *, struct inode *);
extern void d_instantiate_new(struct dentry *, struct inode *);
-extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
-extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *);
extern void __d_drop(struct dentry *dentry);
extern void d_drop(struct dentry *dentry);
extern void d_delete(struct dentry *);
@@ -242,15 +236,11 @@ extern struct dentry * d_obtain_alias(struct inode *);
extern struct dentry * d_obtain_root(struct inode *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
-extern void shrink_dcache_for_umount(struct super_block *);
extern void d_invalidate(struct dentry *);
/* only used at mount-time */
extern struct dentry * d_make_root(struct inode *);
-/* <clickety>-<click> the ramfs-type tree */
-extern void d_genocide(struct dentry *);
-
extern void d_mark_tmpfile(struct file *, struct inode *);
extern void d_tmpfile(struct file *, struct inode *);
@@ -274,12 +264,8 @@ extern void d_move(struct dentry *, struct dentry *);
extern void d_exchange(struct dentry *, struct dentry *);
extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
-/* appendix may either be NULL or be used for transname suffixes */
extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
-extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
-extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
- const struct qstr *name, unsigned *seq);
static inline unsigned d_count(const struct dentry *dentry)
{
@@ -301,20 +287,40 @@ extern char *dentry_path(const struct dentry *, char *, int);
/* Allocation counts.. */
/**
- * dget, dget_dlock - get a reference to a dentry
- * @dentry: dentry to get a reference to
+ * dget_dlock - get a reference to a dentry
+ * @dentry: dentry to get a reference to
*
- * Given a dentry or %NULL pointer increment the reference count
- * if appropriate and return the dentry. A dentry will not be
- * destroyed when it has references.
+ * Given a live dentry, increment the reference count and return the dentry.
+ * Caller must hold @dentry->d_lock. Making sure that dentry is alive is
+ * caller's resonsibility. There are many conditions sufficient to guarantee
+ * that; e.g. anything with non-negative refcount is alive, so's anything
+ * hashed, anything positive, anyone's parent, etc.
*/
static inline struct dentry *dget_dlock(struct dentry *dentry)
{
- if (dentry)
- dentry->d_lockref.count++;
+ dentry->d_lockref.count++;
return dentry;
}
+
+/**
+ * dget - get a reference to a dentry
+ * @dentry: dentry to get a reference to
+ *
+ * Given a dentry or %NULL pointer increment the reference count
+ * if appropriate and return the dentry. A dentry will not be
+ * destroyed when it has references. Conversely, a dentry with
+ * no references can disappear for any number of reasons, starting
+ * with memory pressure. In other words, that primitive is
+ * used to clone an existing reference; using it on something with
+ * zero refcount is a bug.
+ *
+ * NOTE: it will spin if @dentry->d_lock is held. From the deadlock
+ * avoidance point of view it is equivalent to spin_lock()/increment
+ * refcount/spin_unlock(), so calling it under @dentry->d_lock is
+ * always a bug; so's calling it under ->d_lock on any of its descendents.
+ *
+ */
static inline struct dentry *dget(struct dentry *dentry)
{
if (dentry)
@@ -325,12 +331,11 @@ static inline struct dentry *dget(struct dentry *dentry)
extern struct dentry *dget_parent(struct dentry *dentry);
/**
- * d_unhashed - is dentry hashed
- * @dentry: entry to check
+ * d_unhashed - is dentry hashed
+ * @dentry: entry to check
*
- * Returns true if the dentry passed is not currently hashed.
+ * Returns true if the dentry passed is not currently hashed.
*/
-
static inline int d_unhashed(const struct dentry *dentry)
{
return hlist_bl_unhashed(&dentry->d_hash);
@@ -490,14 +495,6 @@ static inline int simple_positive(const struct dentry *dentry)
return d_really_is_positive(dentry) && !d_unhashed(dentry);
}
-extern void d_set_fallthru(struct dentry *dentry);
-
-static inline bool d_is_fallthru(const struct dentry *dentry)
-{
- return dentry->d_flags & DCACHE_FALLTHRU;
-}
-
-
extern int sysctl_vfs_cache_pressure;
static inline unsigned long vfs_pressure_ratio(unsigned long val)
@@ -547,21 +544,6 @@ static inline struct inode *d_backing_inode(const struct dentry *upper)
}
/**
- * d_backing_dentry - Get upper or lower dentry we should be using
- * @upper: The upper layer
- *
- * This is the helper that should be used to get the dentry of the inode that
- * will be used if this dentry were opened as a file. It may be the upper
- * dentry or it may be a lower dentry pinned by the upper.
- *
- * Normal filesystems should not use this to access their own dentries.
- */
-static inline struct dentry *d_backing_dentry(struct dentry *upper)
-{
- return upper;
-}
-
-/**
* d_real - Return the real dentry
* @dentry: the dentry to query
* @inode: inode to select the dentry from multiple layers (can be NULL)
@@ -600,4 +582,14 @@ struct name_snapshot {
void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
void release_dentry_name_snapshot(struct name_snapshot *);
+static inline struct dentry *d_first_child(const struct dentry *dentry)
+{
+ return hlist_entry_safe(dentry->d_children.first, struct dentry, d_sib);
+}
+
+static inline struct dentry *d_next_sibling(const struct dentry *dentry)
+{
+ return hlist_entry_safe(dentry->d_sib.next, struct dentry, d_sib);
+}
+
#endif /* __LINUX_DCACHE_H */