#include <linux/rculist_bl.h>
#include <linux/prefetch.h>
#include <linux/ratelimit.h>
+#include <linux/list_lru.h>
+#include <linux/kasan.h>
+
#include "internal.h"
#include "mount.h"
* - the dcache hash table
* s_anon bl list spinlock protects:
* - the s_anon list (see __d_drop)
- * dcache_lru_lock protects:
+ * dentry->d_sb->s_dentry_lru_lock protects:
* - the dcache lru lists and counters
* d_lock protects:
* - d_flags
* Ordering:
* dentry->d_inode->i_lock
* dentry->d_lock
- * dcache_lru_lock
+ * dentry->d_sb->s_dentry_lru_lock
* dcache_hash_bucket lock
* s_anon lock
*
int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
-static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
EXPORT_SYMBOL(rename_lock);
.age_limit = 45,
};
-static DEFINE_PER_CPU(unsigned int, nr_dentry);
+static DEFINE_PER_CPU(long, nr_dentry);
+static DEFINE_PER_CPU(long, nr_dentry_unused);
#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
-static int get_nr_dentry(void)
+
+/*
+ * Here we resort to our own counters instead of using generic per-cpu counters
+ * for consistency with what the vfs inode code does. We are expected to harvest
+ * better code and performance by having our own specialized counters.
+ *
+ * Please note that the loop is done over all possible CPUs, not over all online
+ * CPUs. The reason for this is that we don't want to play games with CPUs going
+ * on and off. If one of them goes off, we will just keep their counters.
+ *
+ * glommer: See cffbc8a for details, and if you ever intend to change this,
+ * please update all vfs counters to match.
+ */
+static long get_nr_dentry(void)
{
int i;
- int sum = 0;
+ long sum = 0;
for_each_possible_cpu(i)
sum += per_cpu(nr_dentry, i);
return sum < 0 ? 0 : sum;
}
-int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
+static long get_nr_dentry_unused(void)
+{
+ int i;
+ long sum = 0;
+ for_each_possible_cpu(i)
+ sum += per_cpu(nr_dentry_unused, i);
+ return sum < 0 ? 0 : sum;
+}
+
+int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer,
size_t *lenp, loff_t *ppos)
{
dentry_stat.nr_dentry = get_nr_dentry();
- return proc_dointvec(table, write, buffer, lenp, ppos);
+ dentry_stat.nr_unused = get_nr_dentry_unused();
+ return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}
#endif
if (!tcount)
return 0;
}
- mask = ~(~0ul << tcount*8);
+ mask = bytemask_from_count(tcount);
return unlikely(!!((a ^ b) & mask));
}
return dentry_string_cmp(cs, ct, tcount);
}
+struct external_name {
+ union {
+ atomic_t count;
+ struct rcu_head head;
+ } u;
+ unsigned char name[];
+};
+
+static inline struct external_name *external_name(struct dentry *dentry)
+{
+ return container_of(dentry->d_name.name, struct external_name, name[0]);
+}
+
static void __d_free(struct rcu_head *head)
{
struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
- if (dname_external(dentry))
- kfree(dentry->d_name.name);
kmem_cache_free(dentry_cache, dentry);
}
-/*
- * no locks, please.
- */
-static void d_free(struct dentry *dentry)
+static void __d_free_external(struct rcu_head *head)
{
- WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias));
- BUG_ON(dentry->d_count);
- this_cpu_dec(nr_dentry);
- if (dentry->d_op && dentry->d_op->d_release)
- dentry->d_op->d_release(dentry);
+ struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
+ kfree(external_name(dentry));
+ kmem_cache_free(dentry_cache, dentry);
+}
+
+static inline int dname_external(const struct dentry *dentry)
+{
+ return dentry->d_name.name != dentry->d_iname;
+}
+
+static inline void __d_set_inode_and_type(struct dentry *dentry,
+ struct inode *inode,
+ unsigned type_flags)
+{
+ unsigned flags;
+
+ dentry->d_inode = inode;
+ flags = READ_ONCE(dentry->d_flags);
+ flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
+ flags |= type_flags;
+ WRITE_ONCE(dentry->d_flags, flags);
+}
+
+static inline void __d_clear_type_and_inode(struct dentry *dentry)
+{
+ unsigned flags = READ_ONCE(dentry->d_flags);
+ flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
+ WRITE_ONCE(dentry->d_flags, flags);
+ dentry->d_inode = NULL;
+}
+
+static void dentry_free(struct dentry *dentry)
+{
+ WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias));
+ if (unlikely(dname_external(dentry))) {
+ struct external_name *p = external_name(dentry);
+ if (likely(atomic_dec_and_test(&p->u.count))) {
+ call_rcu(&dentry->d_u.d_rcu, __d_free_external);
+ return;
+ }
+ }
/* if dentry was never visible to RCU, immediate free is OK */
if (!(dentry->d_flags & DCACHE_RCUACCESS))
__d_free(&dentry->d_u.d_rcu);
}
/**
- * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
+ * dentry_rcuwalk_invalidate - invalidate in-progress rcu-walk lookups
* @dentry: the target dentry
* After this call, in-progress rcu-walk path lookup will fail. This
* should be called after unhashing, and after changing d_inode (if
* the dentry has not already been unhashed).
*/
-static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
+static inline void dentry_rcuwalk_invalidate(struct dentry *dentry)
{
- assert_spin_locked(&dentry->d_lock);
- /* Go through a barrier */
- write_seqcount_barrier(&dentry->d_seq);
+ lockdep_assert_held(&dentry->d_lock);
+ /* Go through am invalidation barrier */
+ write_seqcount_invalidate(&dentry->d_seq);
}
/*
{
struct inode *inode = dentry->d_inode;
if (inode) {
- dentry->d_inode = NULL;
+ __d_clear_type_and_inode(dentry);
hlist_del_init(&dentry->d_u.d_alias);
spin_unlock(&dentry->d_lock);
spin_unlock(&inode->i_lock);
__releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
- dentry->d_inode = NULL;
+
+ raw_write_seqcount_begin(&dentry->d_seq);
+ __d_clear_type_and_inode(dentry);
hlist_del_init(&dentry->d_u.d_alias);
- dentry_rcuwalk_barrier(dentry);
+ raw_write_seqcount_end(&dentry->d_seq);
spin_unlock(&dentry->d_lock);
spin_unlock(&inode->i_lock);
if (!inode->i_nlink)
}
/*
- * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held.
+ * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
+ * is in use - which includes both the "real" per-superblock
+ * LRU list _and_ the DCACHE_SHRINK_LIST use.
+ *
+ * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
+ * on the shrink list (ie not on the superblock LRU list).
+ *
+ * The per-cpu "nr_dentry_unused" counters are updated with
+ * the DCACHE_LRU_LIST bit.
+ *
+ * These helper functions make sure we always follow the
+ * rules. d_lock must be held by the caller.
*/
-static void dentry_lru_add(struct dentry *dentry)
+#define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
+static void d_lru_add(struct dentry *dentry)
{
- if (list_empty(&dentry->d_lru)) {
- spin_lock(&dcache_lru_lock);
- list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
- dentry->d_sb->s_nr_dentry_unused++;
- dentry_stat.nr_unused++;
- spin_unlock(&dcache_lru_lock);
- }
+ D_FLAG_VERIFY(dentry, 0);
+ dentry->d_flags |= DCACHE_LRU_LIST;
+ this_cpu_inc(nr_dentry_unused);
+ WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
}
-static void __dentry_lru_del(struct dentry *dentry)
+static void d_lru_del(struct dentry *dentry)
{
- list_del_init(&dentry->d_lru);
- dentry->d_flags &= ~DCACHE_SHRINK_LIST;
- dentry->d_sb->s_nr_dentry_unused--;
- dentry_stat.nr_unused--;
+ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
+ dentry->d_flags &= ~DCACHE_LRU_LIST;
+ this_cpu_dec(nr_dentry_unused);
+ WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
}
-/*
- * Remove a dentry with references from the LRU.
- */
-static void dentry_lru_del(struct dentry *dentry)
+static void d_shrink_del(struct dentry *dentry)
{
- if (!list_empty(&dentry->d_lru)) {
- spin_lock(&dcache_lru_lock);
- __dentry_lru_del(dentry);
- spin_unlock(&dcache_lru_lock);
- }
+ D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
+ list_del_init(&dentry->d_lru);
+ dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
+ this_cpu_dec(nr_dentry_unused);
}
-static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list)
+static void d_shrink_add(struct dentry *dentry, struct list_head *list)
{
- spin_lock(&dcache_lru_lock);
- if (list_empty(&dentry->d_lru)) {
- list_add_tail(&dentry->d_lru, list);
- dentry->d_sb->s_nr_dentry_unused++;
- dentry_stat.nr_unused++;
- } else {
- list_move_tail(&dentry->d_lru, list);
- }
- spin_unlock(&dcache_lru_lock);
+ D_FLAG_VERIFY(dentry, 0);
+ list_add(&dentry->d_lru, list);
+ dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST;
+ this_cpu_inc(nr_dentry_unused);
}
-/**
- * d_kill - kill dentry and return parent
- * @dentry: dentry to kill
- * @parent: parent dentry
- *
- * The dentry must already be unhashed and removed from the LRU.
- *
- * If this is the root of the dentry tree, return NULL.
- *
- * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
- * d_kill.
+/*
+ * These can only be called under the global LRU lock, ie during the
+ * callback for freeing the LRU list. "isolate" removes it from the
+ * LRU lists entirely, while shrink_move moves it to the indicated
+ * private list.
*/
-static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
- __releases(dentry->d_lock)
- __releases(parent->d_lock)
- __releases(dentry->d_inode->i_lock)
+static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry)
{
- __list_del_entry(&dentry->d_child);
- /*
- * Inform ascending readers that we are no longer attached to the
- * dentry tree
- */
- dentry->d_flags |= DCACHE_DENTRY_KILLED;
- if (parent)
- spin_unlock(&parent->d_lock);
- dentry_iput(dentry);
- /*
- * dentry_iput drops the locks, at which point nobody (except
- * transient RCU lookups) can reach this dentry.
- */
- d_free(dentry);
- return parent;
+ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
+ dentry->d_flags &= ~DCACHE_LRU_LIST;
+ this_cpu_dec(nr_dentry_unused);
+ list_lru_isolate(lru, &dentry->d_lru);
+}
+
+static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry,
+ struct list_head *list)
+{
+ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
+ dentry->d_flags |= DCACHE_SHRINK_LIST;
+ list_lru_isolate_move(lru, &dentry->d_lru, list);
}
/*
- * Unhash a dentry without inserting an RCU walk barrier or checking that
- * dentry->d_lock is locked. The caller must take care of that, if
- * appropriate.
+ * dentry_lru_(add|del)_list) must be called with d_lock held.
*/
-static void __d_shrink(struct dentry *dentry)
+static void dentry_lru_add(struct dentry *dentry)
{
- if (!d_unhashed(dentry)) {
- struct hlist_bl_head *b;
- if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
- b = &dentry->d_sb->s_anon;
- else
- b = d_hash(dentry->d_parent, dentry->d_name.hash);
-
- hlist_bl_lock(b);
- __hlist_bl_del(&dentry->d_hash);
- dentry->d_hash.pprev = NULL;
- hlist_bl_unlock(b);
- }
+ if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
+ d_lru_add(dentry);
}
/**
void __d_drop(struct dentry *dentry)
{
if (!d_unhashed(dentry)) {
- __d_shrink(dentry);
- dentry_rcuwalk_barrier(dentry);
+ struct hlist_bl_head *b;
+ /*
+ * Hashed dentries are normally on the dentry hashtable,
+ * with the exception of those newly allocated by
+ * d_obtain_alias, which are always IS_ROOT:
+ */
+ if (unlikely(IS_ROOT(dentry)))
+ b = &dentry->d_sb->s_anon;
+ else
+ b = d_hash(dentry->d_parent, dentry->d_name.hash);
+
+ hlist_bl_lock(b);
+ __hlist_bl_del(&dentry->d_hash);
+ dentry->d_hash.pprev = NULL;
+ hlist_bl_unlock(b);
+ dentry_rcuwalk_invalidate(dentry);
}
}
EXPORT_SYMBOL(__d_drop);
}
EXPORT_SYMBOL(d_drop);
+static void __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.
+ */
+ lockref_mark_dead(&dentry->d_lockref);
+
+ /*
+ * inform the fs via d_prune that this dentry is about to be
+ * unhashed and destroyed.
+ */
+ if (dentry->d_flags & DCACHE_OP_PRUNE)
+ dentry->d_op->d_prune(dentry);
+
+ if (dentry->d_flags & DCACHE_LRU_LIST) {
+ if (!(dentry->d_flags & DCACHE_SHRINK_LIST))
+ d_lru_del(dentry);
+ }
+ /* if it was on the hash then remove it */
+ __d_drop(dentry);
+ __list_del_entry(&dentry->d_child);
+ /*
+ * Inform d_walk() that we are no longer attached to the
+ * dentry tree
+ */
+ dentry->d_flags |= DCACHE_DENTRY_KILLED;
+ if (parent)
+ spin_unlock(&parent->d_lock);
+ dentry_iput(dentry);
+ /*
+ * dentry_iput drops the locks, at which point nobody (except
+ * transient RCU lookups) can reach this dentry.
+ */
+ BUG_ON(dentry->d_lockref.count > 0);
+ this_cpu_dec(nr_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;
+ }
+ spin_unlock(&dentry->d_lock);
+ if (likely(can_free))
+ dentry_free(dentry);
+}
+
/*
* Finish off a dentry we've decided to kill.
* dentry->d_lock must be held, returns with it unlocked.
* If ref is non-zero, then decrement the refcount too.
* Returns dentry requiring refcount drop, or NULL if we're done.
*/
-static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
+static struct dentry *dentry_kill(struct dentry *dentry)
__releases(dentry->d_lock)
{
- struct inode *inode;
- struct dentry *parent;
+ struct inode *inode = dentry->d_inode;
+ struct dentry *parent = NULL;
- inode = dentry->d_inode;
- if (inode && !spin_trylock(&inode->i_lock)) {
-relock:
- spin_unlock(&dentry->d_lock);
- cpu_relax();
- return dentry; /* try again with same dentry */
+ if (inode && unlikely(!spin_trylock(&inode->i_lock)))
+ goto failed;
+
+ if (!IS_ROOT(dentry)) {
+ parent = dentry->d_parent;
+ if (unlikely(!spin_trylock(&parent->d_lock))) {
+ if (inode)
+ spin_unlock(&inode->i_lock);
+ goto failed;
+ }
}
+
+ __dentry_kill(dentry);
+ return parent;
+
+failed:
+ spin_unlock(&dentry->d_lock);
+ cpu_relax();
+ return dentry; /* try again with same dentry */
+}
+
+static inline struct dentry *lock_parent(struct dentry *dentry)
+{
+ struct dentry *parent = dentry->d_parent;
if (IS_ROOT(dentry))
- parent = NULL;
+ return NULL;
+ if (unlikely(dentry->d_lockref.count < 0))
+ return NULL;
+ if (likely(spin_trylock(&parent->d_lock)))
+ return parent;
+ rcu_read_lock();
+ spin_unlock(&dentry->d_lock);
+again:
+ parent = ACCESS_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)) {
+ spin_unlock(&parent->d_lock);
+ goto again;
+ }
+ rcu_read_unlock();
+ if (parent != dentry)
+ spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
else
- parent = dentry->d_parent;
- if (parent && !spin_trylock(&parent->d_lock)) {
- if (inode)
- spin_unlock(&inode->i_lock);
- goto relock;
+ parent = NULL;
+ return parent;
+}
+
+/*
+ * Try to do a lockless dput(), and return whether that was successful.
+ *
+ * If unsuccessful, we return false, having already taken the dentry lock.
+ *
+ * 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!
+ */
+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.
+ */
+ ret = lockref_put_return(&dentry->d_lockref);
+
+ /*
+ * If the lockref_put_return() failed due to the lock being held
+ * by somebody else, the fast path has failed. We will need to
+ * get the lock, and then check the count again.
+ */
+ if (unlikely(ret < 0)) {
+ spin_lock(&dentry->d_lock);
+ if (dentry->d_lockref.count > 1) {
+ dentry->d_lockref.count--;
+ spin_unlock(&dentry->d_lock);
+ return 1;
+ }
+ return 0;
}
- if (ref)
- dentry->d_count--;
/*
- * inform the fs via d_prune that this dentry is about to be
- * unhashed and destroyed.
+ * If we weren't the last ref, we're done.
*/
- if (dentry->d_flags & DCACHE_OP_PRUNE)
- dentry->d_op->d_prune(dentry);
+ if (ret)
+ return 1;
- dentry_lru_del(dentry);
- /* if it was on the hash then remove it */
- __d_drop(dentry);
- return d_kill(dentry, parent);
+ /*
+ * 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.
+ */
+ smp_rmb();
+ d_flags = ACCESS_ONCE(dentry->d_flags);
+ d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED;
+
+ /* Nothing to do? Dropping the reference was all we needed? */
+ if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))
+ return 1;
+
+ /*
+ * 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.
+ */
+ spin_lock(&dentry->d_lock);
+
+ /*
+ * Did somebody else grab a reference to it in the meantime, and
+ * we're no longer the last user after all? Alternatively, somebody
+ * else could have killed it and marked it dead. Either way, we
+ * don't need to do anything else.
+ */
+ if (dentry->d_lockref.count) {
+ spin_unlock(&dentry->d_lock);
+ return 1;
+ }
+
+ /*
+ * 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 0;
}
+
/*
* This is dput
*
*/
void dput(struct dentry *dentry)
{
- if (!dentry)
+ if (unlikely(!dentry))
return;
repeat:
- if (dentry->d_count == 1)
- might_sleep();
- spin_lock(&dentry->d_lock);
- BUG_ON(!dentry->d_count);
- if (dentry->d_count > 1) {
- dentry->d_count--;
- spin_unlock(&dentry->d_lock);
+ rcu_read_lock();
+ if (likely(fast_dput(dentry))) {
+ rcu_read_unlock();
return;
}
+ /* Slow case: now with the dentry lock held */
+ rcu_read_unlock();
+
+ /* Unreachable? Get rid of it */
+ if (unlikely(d_unhashed(dentry)))
+ goto kill_it;
+
if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
goto kill_it;
- if (dentry->d_flags & DCACHE_OP_DELETE) {
+ if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
if (dentry->d_op->d_delete(dentry))
goto kill_it;
}
- /* Unreachable? Get rid of it */
- if (d_unhashed(dentry))
- goto kill_it;
-
- dentry->d_flags |= DCACHE_REFERENCED;
+ if (!(dentry->d_flags & DCACHE_REFERENCED))
+ dentry->d_flags |= DCACHE_REFERENCED;
dentry_lru_add(dentry);
- dentry->d_count--;
+ dentry->d_lockref.count--;
spin_unlock(&dentry->d_lock);
return;
kill_it:
- dentry = dentry_kill(dentry, 1);
+ dentry = dentry_kill(dentry);
if (dentry)
goto repeat;
}
EXPORT_SYMBOL(dput);
-/**
- * d_invalidate - invalidate a dentry
- * @dentry: dentry to invalidate
- *
- * Try to invalidate the dentry if it turns out to be
- * possible. If there are other dentries that can be
- * reached through this one we can't delete it and we
- * return -EBUSY. On success we return 0.
- *
- * no dcache lock.
- */
-
-int d_invalidate(struct dentry * dentry)
+
+/* This must be called with d_lock held */
+static inline void __dget_dlock(struct dentry *dentry)
{
- /*
- * If it's already been dropped, return OK.
- */
- spin_lock(&dentry->d_lock);
- if (d_unhashed(dentry)) {
- spin_unlock(&dentry->d_lock);
- return 0;
- }
- /*
- * Check whether to do a partial shrink_dcache
- * to get rid of unused child entries.
- */
- if (!list_empty(&dentry->d_subdirs)) {
- spin_unlock(&dentry->d_lock);
- shrink_dcache_parent(dentry);
- spin_lock(&dentry->d_lock);
- }
-
- /*
- * Somebody else still using it?
- *
- * If it's a directory, we can't drop it
- * for fear of somebody re-populating it
- * with children (even though dropping it
- * would make it unreachable from the root,
- * we might still populate it if it was a
- * working directory or similar).
- * We also need to leave mountpoints alone,
- * directory or not.
- */
- if (dentry->d_count > 1 && dentry->d_inode) {
- if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
- spin_unlock(&dentry->d_lock);
- return -EBUSY;
- }
- }
-
- __d_drop(dentry);
- spin_unlock(&dentry->d_lock);
- return 0;
-}
-EXPORT_SYMBOL(d_invalidate);
-
-/* This must be called with d_lock held */
-static inline void __dget_dlock(struct dentry *dentry)
-{
- dentry->d_count++;
+ dentry->d_lockref.count++;
}
static inline void __dget(struct dentry *dentry)
{
- spin_lock(&dentry->d_lock);
- __dget_dlock(dentry);
- spin_unlock(&dentry->d_lock);
+ lockref_get(&dentry->d_lockref);
}
struct dentry *dget_parent(struct dentry *dentry)
{
+ int gotref;
struct dentry *ret;
+ /*
+ * Do optimistic parent lookup without any
+ * locking.
+ */
+ rcu_read_lock();
+ ret = ACCESS_ONCE(dentry->d_parent);
+ gotref = lockref_get_not_zero(&ret->d_lockref);
+ rcu_read_unlock();
+ if (likely(gotref)) {
+ if (likely(ret == ACCESS_ONCE(dentry->d_parent)))
+ return ret;
+ dput(ret);
+ }
+
repeat:
/*
* Don't need rcu_dereference because we re-check it was correct under
goto repeat;
}
rcu_read_unlock();
- BUG_ON(!ret->d_count);
- ret->d_count++;
+ BUG_ON(!ret->d_lockref.count);
+ ret->d_lockref.count++;
spin_unlock(&ret->d_lock);
return ret;
}
/**
* d_find_alias - grab a hashed alias of inode
* @inode: inode in question
- * @want_discon: flag, used by d_splice_alias, to request
- * that only a DISCONNECTED alias be returned.
*
* If inode has a hashed alias, or is a directory and has any alias,
* acquire the reference to alias and return it. Otherwise return NULL.
* Notice that if inode is a directory there can be only one alias and
* it can be unhashed only if it has no children, or if it is the root
- * of a filesystem.
+ * of a filesystem, or if the directory was renamed and d_revalidate
+ * was the first vfs operation to notice.
*
* If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
- * any other hashed alias over that one unless @want_discon is set,
- * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
+ * any other hashed alias over that one.
*/
-static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
+static struct dentry *__d_find_alias(struct inode *inode)
{
struct dentry *alias, *discon_alias;
if (IS_ROOT(alias) &&
(alias->d_flags & DCACHE_DISCONNECTED)) {
discon_alias = alias;
- } else if (!want_discon) {
+ } else {
__dget_dlock(alias);
spin_unlock(&alias->d_lock);
return alias;
alias = discon_alias;
spin_lock(&alias->d_lock);
if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
- if (IS_ROOT(alias) &&
- (alias->d_flags & DCACHE_DISCONNECTED)) {
- __dget_dlock(alias);
- spin_unlock(&alias->d_lock);
- return alias;
- }
+ __dget_dlock(alias);
+ spin_unlock(&alias->d_lock);
+ return alias;
}
spin_unlock(&alias->d_lock);
goto again;
if (!hlist_empty(&inode->i_dentry)) {
spin_lock(&inode->i_lock);
- de = __d_find_alias(inode, 0);
+ de = __d_find_alias(inode);
spin_unlock(&inode->i_lock);
}
return de;
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_count) {
- __dget_dlock(dentry);
- __d_drop(dentry);
- spin_unlock(&dentry->d_lock);
- spin_unlock(&inode->i_lock);
- dput(dentry);
- goto restart;
+ 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);
}
spin_unlock(&dentry->d_lock);
}
}
EXPORT_SYMBOL(d_prune_aliases);
-/*
- * Try to throw away a dentry - free the inode, dput the parent.
- * Requires dentry->d_lock is held, and dentry->d_count == 0.
- * Releases dentry->d_lock.
- *
- * This may fail if locks cannot be acquired no problem, just try again.
- */
-static void try_prune_one_dentry(struct dentry *dentry)
- __releases(dentry->d_lock)
+static void shrink_dentry_list(struct list_head *list)
{
- struct dentry *parent;
-
- parent = dentry_kill(dentry, 0);
- /*
- * If dentry_kill returns NULL, we have nothing more to do.
- * if it returns the same dentry, trylocks failed. In either
- * case, just loop again.
- *
- * Otherwise, we need to prune ancestors too. This is necessary
- * to prevent quadratic behavior of shrink_dcache_parent(), but
- * is also expected to be beneficial in reducing dentry cache
- * fragmentation.
- */
- if (!parent)
- return;
- if (parent == dentry)
- return;
+ struct dentry *dentry, *parent;
- /* Prune ancestors. */
- dentry = parent;
- while (dentry) {
+ while (!list_empty(list)) {
+ struct inode *inode;
+ dentry = list_entry(list->prev, struct dentry, d_lru);
spin_lock(&dentry->d_lock);
- if (dentry->d_count > 1) {
- dentry->d_count--;
+ parent = lock_parent(dentry);
+
+ /*
+ * The dispose list is isolated and dentries are not accounted
+ * to the LRU here, so we can simply remove it from the list
+ * here regardless of whether it is referenced or not.
+ */
+ d_shrink_del(dentry);
+
+ /*
+ * We found an inuse dentry which was not removed from
+ * the LRU because of laziness during lookup. Do not free it.
+ */
+ if (dentry->d_lockref.count > 0) {
spin_unlock(&dentry->d_lock);
- return;
+ if (parent)
+ spin_unlock(&parent->d_lock);
+ continue;
}
- dentry = dentry_kill(dentry, 1);
- }
-}
-static void shrink_dentry_list(struct list_head *list)
-{
- struct dentry *dentry;
- rcu_read_lock();
- for (;;) {
- dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
- if (&dentry->d_lru == list)
- break; /* empty */
- spin_lock(&dentry->d_lock);
- if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
+ if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
+ bool can_free = dentry->d_flags & DCACHE_MAY_FREE;
spin_unlock(&dentry->d_lock);
+ if (parent)
+ spin_unlock(&parent->d_lock);
+ if (can_free)
+ dentry_free(dentry);
continue;
}
- /*
- * We found an inuse dentry which was not removed from
- * the LRU because of laziness during lookup. Do not free
- * it - just keep it off the LRU list.
- */
- if (dentry->d_count) {
- dentry_lru_del(dentry);
+ inode = dentry->d_inode;
+ if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
+ d_shrink_add(dentry, list);
spin_unlock(&dentry->d_lock);
+ if (parent)
+ spin_unlock(&parent->d_lock);
continue;
}
- rcu_read_unlock();
+ __dentry_kill(dentry);
- try_prune_one_dentry(dentry);
+ /*
+ * We need to prune ancestors too. This is necessary to prevent
+ * quadratic behavior of shrink_dcache_parent(), but is also
+ * expected to be beneficial in reducing dentry cache
+ * fragmentation.
+ */
+ dentry = parent;
+ while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) {
+ parent = lock_parent(dentry);
+ if (dentry->d_lockref.count != 1) {
+ dentry->d_lockref.count--;
+ spin_unlock(&dentry->d_lock);
+ if (parent)
+ spin_unlock(&parent->d_lock);
+ break;
+ }
+ inode = dentry->d_inode; /* can't be NULL */
+ if (unlikely(!spin_trylock(&inode->i_lock))) {
+ spin_unlock(&dentry->d_lock);
+ if (parent)
+ spin_unlock(&parent->d_lock);
+ cpu_relax();
+ continue;
+ }
+ __dentry_kill(dentry);
+ dentry = parent;
+ }
+ }
+}
- rcu_read_lock();
+static enum lru_status dentry_lru_isolate(struct list_head *item,
+ struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+{
+ struct list_head *freeable = arg;
+ struct dentry *dentry = container_of(item, struct dentry, d_lru);
+
+
+ /*
+ * we are inverting the lru lock/dentry->d_lock here,
+ * so use a trylock. If we fail to get the lock, just skip
+ * it
+ */
+ if (!spin_trylock(&dentry->d_lock))
+ return LRU_SKIP;
+
+ /*
+ * Referenced dentries are still in use. If they have active
+ * counts, just remove them from the LRU. Otherwise give them
+ * another pass through the LRU.
+ */
+ if (dentry->d_lockref.count) {
+ d_lru_isolate(lru, dentry);
+ spin_unlock(&dentry->d_lock);
+ return LRU_REMOVED;
}
- rcu_read_unlock();
+
+ if (dentry->d_flags & DCACHE_REFERENCED) {
+ dentry->d_flags &= ~DCACHE_REFERENCED;
+ spin_unlock(&dentry->d_lock);
+
+ /*
+ * The list move itself will be made by the common LRU code. At
+ * this point, we've dropped the dentry->d_lock but keep the
+ * lru lock. This is safe to do, since every list movement is
+ * protected by the lru lock even if both locks are held.
+ *
+ * This is guaranteed by the fact that all LRU management
+ * functions are intermediated by the LRU API calls like
+ * list_lru_add and list_lru_del. List movement in this file
+ * only ever occur through this functions or through callbacks
+ * like this one, that are called from the LRU API.
+ *
+ * The only exceptions to this are functions like
+ * shrink_dentry_list, and code that first checks for the
+ * DCACHE_SHRINK_LIST flag. Those are guaranteed to be
+ * operating only with stack provided lists after they are
+ * properly isolated from the main list. It is thus, always a
+ * local access.
+ */
+ return LRU_ROTATE;
+ }
+
+ d_lru_shrink_move(lru, dentry, freeable);
+ spin_unlock(&dentry->d_lock);
+
+ return LRU_REMOVED;
}
/**
* prune_dcache_sb - shrink the dcache
* @sb: superblock
- * @count: number of entries to try to free
+ * @sc: shrink control, passed to list_lru_shrink_walk()
*
- * Attempt to shrink the superblock dcache LRU by @count entries. This is
- * done when we need more memory an called from the superblock shrinker
+ * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This
+ * is done when we need more memory and called from the superblock shrinker
* function.
*
* This function may fail to free any resources if all the dentries are in
* use.
*/
-void prune_dcache_sb(struct super_block *sb, int count)
+long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc)
{
- struct dentry *dentry;
- LIST_HEAD(referenced);
- LIST_HEAD(tmp);
-
-relock:
- spin_lock(&dcache_lru_lock);
- while (!list_empty(&sb->s_dentry_lru)) {
- dentry = list_entry(sb->s_dentry_lru.prev,
- struct dentry, d_lru);
- BUG_ON(dentry->d_sb != sb);
-
- if (!spin_trylock(&dentry->d_lock)) {
- spin_unlock(&dcache_lru_lock);
- cpu_relax();
- goto relock;
- }
+ LIST_HEAD(dispose);
+ long freed;
- if (dentry->d_flags & DCACHE_REFERENCED) {
- dentry->d_flags &= ~DCACHE_REFERENCED;
- list_move(&dentry->d_lru, &referenced);
- spin_unlock(&dentry->d_lock);
- } else {
- list_move_tail(&dentry->d_lru, &tmp);
- dentry->d_flags |= DCACHE_SHRINK_LIST;
- spin_unlock(&dentry->d_lock);
- if (!--count)
- break;
- }
- cond_resched_lock(&dcache_lru_lock);
- }
- if (!list_empty(&referenced))
- list_splice(&referenced, &sb->s_dentry_lru);
- spin_unlock(&dcache_lru_lock);
+ freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc,
+ dentry_lru_isolate, &dispose);
+ shrink_dentry_list(&dispose);
+ return freed;
+}
+
+static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
+ struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+{
+ struct list_head *freeable = arg;
+ struct dentry *dentry = container_of(item, struct dentry, d_lru);
+
+ /*
+ * we are inverting the lru lock/dentry->d_lock here,
+ * so use a trylock. If we fail to get the lock, just skip
+ * it
+ */
+ if (!spin_trylock(&dentry->d_lock))
+ return LRU_SKIP;
- shrink_dentry_list(&tmp);
+ d_lru_shrink_move(lru, dentry, freeable);
+ spin_unlock(&dentry->d_lock);
+
+ return LRU_REMOVED;
}
+
/**
* shrink_dcache_sb - shrink dcache for a superblock
* @sb: superblock
*/
void shrink_dcache_sb(struct super_block *sb)
{
- LIST_HEAD(tmp);
-
- spin_lock(&dcache_lru_lock);
- while (!list_empty(&sb->s_dentry_lru)) {
- list_splice_init(&sb->s_dentry_lru, &tmp);
- spin_unlock(&dcache_lru_lock);
- shrink_dentry_list(&tmp);
- spin_lock(&dcache_lru_lock);
- }
- spin_unlock(&dcache_lru_lock);
-}
-EXPORT_SYMBOL(shrink_dcache_sb);
-
-/*
- * destroy a single subtree of dentries for unmount
- * - see the comments on shrink_dcache_for_umount() for a description of the
- * locking
- */
-static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
-{
- struct dentry *parent;
-
- BUG_ON(!IS_ROOT(dentry));
-
- for (;;) {
- /* descend to the first leaf in the current subtree */
- while (!list_empty(&dentry->d_subdirs))
- dentry = list_entry(dentry->d_subdirs.next,
- struct dentry, d_child);
-
- /* consume the dentries from this leaf up through its parents
- * until we find one with children or run out altogether */
- do {
- struct inode *inode;
-
- /*
- * inform the fs that this dentry is about to be
- * unhashed and destroyed.
- */
- if (dentry->d_flags & DCACHE_OP_PRUNE)
- dentry->d_op->d_prune(dentry);
-
- dentry_lru_del(dentry);
- __d_shrink(dentry);
-
- if (dentry->d_count != 0) {
- printk(KERN_ERR
- "BUG: Dentry %p{i=%lx,n=%s}"
- " still in use (%d)"
- " [unmount of %s %s]\n",
- dentry,
- dentry->d_inode ?
- dentry->d_inode->i_ino : 0UL,
- dentry->d_name.name,
- dentry->d_count,
- dentry->d_sb->s_type->name,
- dentry->d_sb->s_id);
- BUG();
- }
-
- if (IS_ROOT(dentry)) {
- parent = NULL;
- list_del(&dentry->d_child);
- } else {
- parent = dentry->d_parent;
- parent->d_count--;
- list_del(&dentry->d_child);
- }
-
- inode = dentry->d_inode;
- if (inode) {
- dentry->d_inode = NULL;
- hlist_del_init(&dentry->d_u.d_alias);
- if (dentry->d_op && dentry->d_op->d_iput)
- dentry->d_op->d_iput(dentry, inode);
- else
- iput(inode);
- }
+ long freed;
- d_free(dentry);
+ do {
+ LIST_HEAD(dispose);
- /* finished when we fall off the top of the tree,
- * otherwise we ascend to the parent and move to the
- * next sibling if there is one */
- if (!parent)
- return;
- dentry = parent;
- } while (list_empty(&dentry->d_subdirs));
+ freed = list_lru_walk(&sb->s_dentry_lru,
+ dentry_lru_isolate_shrink, &dispose, UINT_MAX);
- dentry = list_entry(dentry->d_subdirs.next,
- struct dentry, d_child);
- }
+ this_cpu_sub(nr_dentry_unused, freed);
+ shrink_dentry_list(&dispose);
+ } while (freed > 0);
}
+EXPORT_SYMBOL(shrink_dcache_sb);
-/*
- * destroy the dentries attached to a superblock on unmounting
- * - we don't need to use dentry->d_lock because:
- * - the superblock is detached from all mountings and open files, so the
- * dentry trees will not be rearranged by the VFS
- * - s_umount is write-locked, so the memory pressure shrinker will ignore
- * any dentries belonging to this superblock that it comes across
- * - the filesystem itself is no longer permitted to rearrange the dentries
- * in this superblock
- */
-void shrink_dcache_for_umount(struct super_block *sb)
-{
- struct dentry *dentry;
-
- if (down_read_trylock(&sb->s_umount))
- BUG();
-
- dentry = sb->s_root;
- sb->s_root = NULL;
- dentry->d_count--;
- shrink_dcache_for_umount_subtree(dentry);
-
- while (!hlist_bl_empty(&sb->s_anon)) {
- dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
- shrink_dcache_for_umount_subtree(dentry);
- }
-}
+/**
+ * enum d_walk_ret - action to talke during tree walk
+ * @D_WALK_CONTINUE: contrinue walk
+ * @D_WALK_QUIT: quit walk
+ * @D_WALK_NORETRY: quit when retry is needed
+ * @D_WALK_SKIP: skip this dentry and its children
+ */
+enum d_walk_ret {
+ D_WALK_CONTINUE,
+ D_WALK_QUIT,
+ D_WALK_NORETRY,
+ D_WALK_SKIP,
+};
-/*
- * Search for at least 1 mount point in the dentry's subdirs.
- * We descend to the next level whenever the d_subdirs
- * list is non-empty and continue searching.
- */
-
/**
- * have_submounts - check for mounts over a dentry
- * @parent: dentry to check.
+ * d_walk - walk the dentry tree
+ * @parent: start of walk
+ * @data: data passed to @enter() and @finish()
+ * @enter: callback when first entering the dentry
+ * @finish: callback when successfully finished the walk
*
- * Return true if the parent or its subdirectories contain
- * a mount point
+ * The @enter() and @finish() callbacks are called with d_lock held.
*/
-int have_submounts(struct dentry *parent)
+static void d_walk(struct dentry *parent, void *data,
+ enum d_walk_ret (*enter)(void *, struct dentry *),
+ void (*finish)(void *))
{
struct dentry *this_parent;
struct list_head *next;
- unsigned seq;
- int locked = 0;
+ unsigned seq = 0;
+ enum d_walk_ret ret;
+ bool retry = true;
- seq = read_seqbegin(&rename_lock);
again:
+ read_seqbegin_or_lock(&rename_lock, &seq);
this_parent = parent;
-
- if (d_mountpoint(parent))
- goto positive;
spin_lock(&this_parent->d_lock);
+
+ ret = enter(data, this_parent);
+ switch (ret) {
+ case D_WALK_CONTINUE:
+ break;
+ case D_WALK_QUIT:
+ case D_WALK_SKIP:
+ goto out_unlock;
+ case D_WALK_NORETRY:
+ retry = false;
+ break;
+ }
repeat:
next = this_parent->d_subdirs.next;
resume:
next = tmp->next;
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- /* Have we found a mount point ? */
- if (d_mountpoint(dentry)) {
+
+ ret = enter(data, dentry);
+ switch (ret) {
+ case D_WALK_CONTINUE:
+ break;
+ case D_WALK_QUIT:
spin_unlock(&dentry->d_lock);
- spin_unlock(&this_parent->d_lock);
- goto positive;
+ goto out_unlock;
+ case D_WALK_NORETRY:
+ retry = false;
+ break;
+ case D_WALK_SKIP:
+ spin_unlock(&dentry->d_lock);
+ continue;
}
+
if (!list_empty(&dentry->d_subdirs)) {
spin_unlock(&this_parent->d_lock);
spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
spin_lock(&this_parent->d_lock);
/* might go back up the wrong parent if we have had a rename. */
- if (!locked && read_seqretry(&rename_lock, seq))
+ if (need_seqretry(&rename_lock, seq))
goto rename_retry;
/* go into the first sibling still alive */
do {
rcu_read_unlock();
goto resume;
}
- if (!locked && read_seqretry(&rename_lock, seq))
+ if (need_seqretry(&rename_lock, seq))
goto rename_retry;
- spin_unlock(&this_parent->d_lock);
rcu_read_unlock();
- if (locked)
- write_sequnlock(&rename_lock);
- return 0; /* No mount points found in tree */
-positive:
- if (!locked && read_seqretry(&rename_lock, seq))
- goto rename_retry_unlocked;
- if (locked)
- write_sequnlock(&rename_lock);
- return 1;
+ if (finish)
+ finish(data);
+
+out_unlock:
+ spin_unlock(&this_parent->d_lock);
+ done_seqretry(&rename_lock, seq);
+ return;
rename_retry:
spin_unlock(&this_parent->d_lock);
rcu_read_unlock();
- if (locked)
- goto again;
-rename_retry_unlocked:
- locked = 1;
- write_seqlock(&rename_lock);
+ BUG_ON(seq & 1);
+ if (!retry)
+ return;
+ seq = 1;
goto again;
}
-EXPORT_SYMBOL(have_submounts);
/*
- * 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
- * searching.
- *
- * It returns zero iff there are no unused children,
- * otherwise it returns the number of children moved to
- * the end of the unused list. This may not be the total
- * number of unused children, because select_parent can
- * drop the lock and return early due to latency
- * constraints.
+ * Search for at least 1 mount point in the dentry's subdirs.
+ * We descend to the next level whenever the d_subdirs
+ * list is non-empty and continue searching.
+ */
+
+static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
+{
+ int *ret = data;
+ if (d_mountpoint(dentry)) {
+ *ret = 1;
+ return D_WALK_QUIT;
+ }
+ return D_WALK_CONTINUE;
+}
+
+/**
+ * have_submounts - check for mounts over a dentry
+ * @parent: dentry to check.
+ *
+ * Return true if the parent or its subdirectories contain
+ * a mount point
+ */
+int have_submounts(struct dentry *parent)
+{
+ int ret = 0;
+
+ d_walk(parent, &ret, check_mount, NULL);
+
+ return ret;
+}
+EXPORT_SYMBOL(have_submounts);
+
+/*
+ * Called by mount code to set a mountpoint and check if the mountpoint is
+ * reachable (e.g. NFS can unhash a directory dentry and then the complete
+ * subtree can become unreachable).
+ *
+ * Only one of d_invalidate() and d_set_mounted() must succeed. For
+ * this reason take rename_lock and d_lock on dentry and ancestors.
+ */
+int d_set_mounted(struct dentry *dentry)
+{
+ struct dentry *p;
+ int ret = -ENOENT;
+ write_seqlock(&rename_lock);
+ for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
+ /* Need exclusion wrt. d_invalidate() */
+ spin_lock(&p->d_lock);
+ if (unlikely(d_unhashed(p))) {
+ spin_unlock(&p->d_lock);
+ goto out;
+ }
+ spin_unlock(&p->d_lock);
+ }
+ spin_lock(&dentry->d_lock);
+ if (!d_unlinked(dentry)) {
+ dentry->d_flags |= DCACHE_MOUNTED;
+ ret = 0;
+ }
+ spin_unlock(&dentry->d_lock);
+out:
+ write_sequnlock(&rename_lock);
+ return ret;
+}
+
+/*
+ * 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
+ * searching.
+ *
+ * It returns zero iff there are no unused children,
+ * otherwise it returns the number of children moved to
+ * the end of the unused list. This may not be the total
+ * number of unused children, because select_parent can
+ * drop the lock and return early due to latency
+ * constraints.
+ */
+
+struct select_data {
+ struct dentry *start;
+ struct list_head dispose;
+ int found;
+};
+
+static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
+{
+ struct select_data *data = _data;
+ enum d_walk_ret ret = D_WALK_CONTINUE;
+
+ if (data->start == dentry)
+ goto out;
+
+ 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++;
+ }
+ }
+ /*
+ * We can return to the caller if we have found some (this
+ * ensures forward progress). We'll be coming back to find
+ * the rest.
+ */
+ if (!list_empty(&data->dispose))
+ ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
+out:
+ return ret;
+}
+
+/**
+ * shrink_dcache_parent - prune dcache
+ * @parent: parent of entries to prune
+ *
+ * Prune the dcache to remove unused children of the parent dentry.
+ */
+void shrink_dcache_parent(struct dentry *parent)
+{
+ for (;;) {
+ struct select_data data;
+
+ INIT_LIST_HEAD(&data.dispose);
+ data.start = parent;
+ data.found = 0;
+
+ d_walk(parent, &data, select_collect, NULL);
+ if (!data.found)
+ break;
+
+ shrink_dentry_list(&data.dispose);
+ cond_resched();
+ }
+}
+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))
+ return D_WALK_CONTINUE;
+
+ /* root with refcount 1 is fine */
+ if (dentry == _data && dentry->d_lockref.count == 1)
+ return D_WALK_CONTINUE;
+
+ printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} "
+ " still in use (%d) [unmount of %s %s]\n",
+ dentry,
+ dentry->d_inode ?
+ dentry->d_inode->i_ino : 0UL,
+ dentry,
+ dentry->d_lockref.count,
+ dentry->d_sb->s_type->name,
+ dentry->d_sb->s_id);
+ WARN_ON(1);
+ return D_WALK_CONTINUE;
+}
+
+static void do_one_tree(struct dentry *dentry)
+{
+ shrink_dcache_parent(dentry);
+ d_walk(dentry, dentry, umount_check, NULL);
+ d_drop(dentry);
+ dput(dentry);
+}
+
+/*
+ * destroy the dentries attached to a superblock on unmounting
*/
-static int select_parent(struct dentry *parent, struct list_head *dispose)
+void shrink_dcache_for_umount(struct super_block *sb)
{
- struct dentry *this_parent;
- struct list_head *next;
- unsigned seq;
- int found = 0;
- int locked = 0;
+ struct dentry *dentry;
- seq = read_seqbegin(&rename_lock);
-again:
- this_parent = parent;
- spin_lock(&this_parent->d_lock);
-repeat:
- next = this_parent->d_subdirs.next;
-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;
+ WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked");
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+ dentry = sb->s_root;
+ sb->s_root = NULL;
+ do_one_tree(dentry);
- /*
- * move only zero ref count dentries to the dispose list.
- *
- * Those which are presently on the shrink list, being processed
- * by shrink_dentry_list(), shouldn't be moved. Otherwise the
- * loop in shrink_dcache_parent() might not make any progress
- * and loop forever.
- */
- if (dentry->d_count) {
- dentry_lru_del(dentry);
- } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
- dentry_lru_move_list(dentry, dispose);
- dentry->d_flags |= DCACHE_SHRINK_LIST;
- found++;
- }
- /*
- * We can return to the caller if we have found some (this
- * ensures forward progress). We'll be coming back to find
- * the rest.
- */
- if (found && need_resched()) {
- spin_unlock(&dentry->d_lock);
- rcu_read_lock();
- goto out;
- }
+ while (!hlist_bl_empty(&sb->s_anon)) {
+ dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash));
+ do_one_tree(dentry);
+ }
+}
- /*
- * Descend a level if the d_subdirs list is non-empty.
- */
- if (!list_empty(&dentry->d_subdirs)) {
- spin_unlock(&this_parent->d_lock);
- spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
- this_parent = dentry;
- spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
- goto repeat;
- }
+struct detach_data {
+ struct select_data select;
+ struct dentry *mountpoint;
+};
+static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry)
+{
+ struct detach_data *data = _data;
- spin_unlock(&dentry->d_lock);
+ if (d_mountpoint(dentry)) {
+ __dget_dlock(dentry);
+ data->mountpoint = dentry;
+ return D_WALK_QUIT;
}
- /*
- * All done at this level ... ascend and resume the search.
- */
- rcu_read_lock();
-ascend:
- if (this_parent != parent) {
- struct dentry *child = this_parent;
- this_parent = child->d_parent;
- spin_unlock(&child->d_lock);
- spin_lock(&this_parent->d_lock);
+ return select_collect(&data->select, dentry);
+}
- /* might go back up the wrong parent if we have had a rename. */
- if (!locked && read_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;
- }
-out:
- if (!locked && read_seqretry(&rename_lock, seq))
- goto rename_retry;
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
- if (locked)
- write_sequnlock(&rename_lock);
- return found;
+static void check_and_drop(void *_data)
+{
+ struct detach_data *data = _data;
-rename_retry:
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
- if (found)
- return found;
- if (locked)
- goto again;
- locked = 1;
- write_seqlock(&rename_lock);
- goto again;
+ if (!data->mountpoint && !data->select.found)
+ __d_drop(data->select.start);
}
/**
- * shrink_dcache_parent - prune dcache
- * @parent: parent of entries to prune
+ * d_invalidate - detach submounts, prune dcache, and drop
+ * @dentry: dentry to invalidate (aka detach, prune and drop)
*
- * Prune the dcache to remove unused children of the parent dentry.
+ * no dcache lock.
+ *
+ * The final d_drop is done as an atomic operation relative to
+ * rename_lock ensuring there are no races with d_set_mounted. This
+ * ensures there are no unhashed dentries on the path to a mountpoint.
*/
-void shrink_dcache_parent(struct dentry * parent)
+void d_invalidate(struct dentry *dentry)
{
- LIST_HEAD(dispose);
- int found;
+ /*
+ * If it's already been dropped, return OK.
+ */
+ spin_lock(&dentry->d_lock);
+ if (d_unhashed(dentry)) {
+ spin_unlock(&dentry->d_lock);
+ return;
+ }
+ spin_unlock(&dentry->d_lock);
+
+ /* Negative dentries can be dropped without further checks */
+ if (!dentry->d_inode) {
+ d_drop(dentry);
+ return;
+ }
+
+ for (;;) {
+ struct detach_data data;
+
+ data.mountpoint = NULL;
+ INIT_LIST_HEAD(&data.select.dispose);
+ data.select.start = dentry;
+ data.select.found = 0;
+
+ d_walk(dentry, &data, detach_and_collect, check_and_drop);
+
+ if (data.select.found)
+ shrink_dentry_list(&data.select.dispose);
+
+ if (data.mountpoint) {
+ detach_mounts(data.mountpoint);
+ dput(data.mountpoint);
+ }
+
+ if (!data.mountpoint && !data.select.found)
+ break;
- while ((found = select_parent(parent, &dispose)) != 0) {
- shrink_dentry_list(&dispose);
cond_resched();
}
}
-EXPORT_SYMBOL(shrink_dcache_parent);
+EXPORT_SYMBOL(d_invalidate);
/**
* __d_alloc - allocate a dcache entry
*/
dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
if (name->len > DNAME_INLINE_LEN-1) {
- dname = kmalloc(name->len + 1, GFP_KERNEL);
- if (!dname) {
+ size_t size = offsetof(struct external_name, name[1]);
+ struct external_name *p = kmalloc(size + name->len, GFP_KERNEL);
+ if (!p) {
kmem_cache_free(dentry_cache, dentry);
return NULL;
}
+ atomic_set(&p->u.count, 1);
+ dname = p->name;
+ if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS))
+ kasan_unpoison_shadow(dname,
+ round_up(name->len + 1, sizeof(unsigned long)));
} else {
dname = dentry->d_iname;
}
smp_wmb();
dentry->d_name.name = dname;
- dentry->d_count = 1;
+ dentry->d_lockref.count = 1;
dentry->d_flags = 0;
spin_lock_init(&dentry->d_lock);
seqcount_init(&dentry->d_seq);
struct dentry *dentry = __d_alloc(parent->d_sb, name);
if (!dentry)
return NULL;
-
+ dentry->d_flags |= DCACHE_RCUACCESS;
spin_lock(&parent->d_lock);
/*
* don't need child lock because it is not subject
}
EXPORT_SYMBOL(d_alloc);
+/**
+ * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
+ * @sb: the superblock
+ * @name: qstr of the name
+ *
+ * For a filesystem that just pins its dentries in memory and never
+ * performs lookups at all, return an unhashed IS_ROOT dentry.
+ */
struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
{
- struct dentry *dentry = __d_alloc(sb, name);
- if (dentry)
- dentry->d_flags |= DCACHE_DISCONNECTED;
- return dentry;
+ return __d_alloc(sb, name);
}
EXPORT_SYMBOL(d_alloc_pseudo);
DCACHE_OP_COMPARE |
DCACHE_OP_REVALIDATE |
DCACHE_OP_WEAK_REVALIDATE |
- DCACHE_OP_DELETE ));
+ DCACHE_OP_DELETE |
+ DCACHE_OP_SELECT_INODE |
+ DCACHE_OP_REAL));
dentry->d_op = op;
if (!op)
return;
dentry->d_flags |= DCACHE_OP_DELETE;
if (op->d_prune)
dentry->d_flags |= DCACHE_OP_PRUNE;
+ if (op->d_select_inode)
+ dentry->d_flags |= DCACHE_OP_SELECT_INODE;
+ if (op->d_real)
+ dentry->d_flags |= DCACHE_OP_REAL;
}
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;
+
+ if (!inode)
+ return DCACHE_MISS_TYPE;
+
+ if (S_ISDIR(inode->i_mode)) {
+ add_flags = DCACHE_DIRECTORY_TYPE;
+ if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) {
+ if (unlikely(!inode->i_op->lookup))
+ add_flags = DCACHE_AUTODIR_TYPE;
+ else
+ inode->i_opflags |= IOP_LOOKUP;
+ }
+ goto type_determined;
+ }
+
+ if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
+ if (unlikely(inode->i_op->follow_link)) {
+ add_flags = DCACHE_SYMLINK_TYPE;
+ goto type_determined;
+ }
+ inode->i_opflags |= IOP_NOFOLLOW;
+ }
+
+ if (unlikely(!S_ISREG(inode->i_mode)))
+ add_flags = DCACHE_SPECIAL_TYPE;
+
+type_determined:
+ if (unlikely(IS_AUTOMOUNT(inode)))
+ add_flags |= DCACHE_NEED_AUTOMOUNT;
+ return add_flags;
+}
+
static void __d_instantiate(struct dentry *dentry, struct inode *inode)
{
+ unsigned add_flags = d_flags_for_inode(inode);
+
spin_lock(&dentry->d_lock);
- if (inode) {
- if (unlikely(IS_AUTOMOUNT(inode)))
- dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
+ if (inode)
hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
- }
- dentry->d_inode = inode;
- dentry_rcuwalk_barrier(dentry);
+ raw_write_seqcount_begin(&dentry->d_seq);
+ __d_set_inode_and_type(dentry, inode, add_flags);
+ raw_write_seqcount_end(&dentry->d_seq);
spin_unlock(&dentry->d_lock);
fsnotify_d_instantiate(dentry, inode);
}
EXPORT_SYMBOL(d_instantiate_unique);
+/**
+ * d_instantiate_no_diralias - instantiate a non-aliased dentry
+ * @entry: dentry to complete
+ * @inode: inode to attach to this dentry
+ *
+ * Fill in inode information in the entry. If a directory alias is found, then
+ * return an error (and drop inode). Together with d_materialise_unique() this
+ * guarantees that a directory inode may never have more than one alias.
+ */
+int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode)
+{
+ BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
+
+ spin_lock(&inode->i_lock);
+ if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) {
+ spin_unlock(&inode->i_lock);
+ iput(inode);
+ return -EBUSY;
+ }
+ __d_instantiate(entry, inode);
+ spin_unlock(&inode->i_lock);
+ security_d_instantiate(entry, inode);
+
+ return 0;
+}
+EXPORT_SYMBOL(d_instantiate_no_diralias);
+
struct dentry *d_make_root(struct inode *root_inode)
{
struct dentry *res = NULL;
}
EXPORT_SYMBOL(d_find_any_alias);
-/**
- * d_obtain_alias - find or allocate a dentry for a given inode
- * @inode: inode to allocate the dentry for
- *
- * Obtain a dentry for an inode resulting from NFS filehandle conversion or
- * similar open by handle operations. The returned dentry may be anonymous,
- * or may have a full name (if the inode was already in the cache).
- *
- * When called on a directory inode, we must ensure that the inode only ever
- * has one dentry. If a dentry is found, that is returned instead of
- * allocating a new one.
- *
- * On successful return, the reference to the inode has been transferred
- * to the dentry. In case of an error the reference on the inode is released.
- * To make it easier to use in export operations a %NULL or IS_ERR inode may
- * be passed in and will be the error will be propagate to the return value,
- * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
- */
-struct dentry *d_obtain_alias(struct inode *inode)
+static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected)
{
static const struct qstr anonstring = QSTR_INIT("/", 1);
struct dentry *tmp;
struct dentry *res;
+ unsigned add_flags;
if (!inode)
return ERR_PTR(-ESTALE);
}
/* attach a disconnected dentry */
+ add_flags = d_flags_for_inode(inode);
+
+ if (disconnected)
+ add_flags |= DCACHE_DISCONNECTED;
+
spin_lock(&tmp->d_lock);
- tmp->d_inode = inode;
- tmp->d_flags |= DCACHE_DISCONNECTED;
+ __d_set_inode_and_type(tmp, inode, add_flags);
hlist_add_head(&tmp->d_u.d_alias, &inode->i_dentry);
hlist_bl_lock(&tmp->d_sb->s_anon);
hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
iput(inode);
return res;
}
-EXPORT_SYMBOL(d_obtain_alias);
/**
- * d_splice_alias - splice a disconnected dentry into the tree if one exists
- * @inode: the inode which may have a disconnected dentry
- * @dentry: a negative dentry which we want to point to the inode.
- *
- * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
- * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
- * and return it, else simply d_add the inode to the dentry and return NULL.
+ * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
+ * @inode: inode to allocate the dentry for
*
- * This is needed in the lookup routine of any filesystem that is exportable
- * (via knfsd) so that we can build dcache paths to directories effectively.
+ * Obtain a dentry for an inode resulting from NFS filehandle conversion or
+ * similar open by handle operations. The returned dentry may be anonymous,
+ * or may have a full name (if the inode was already in the cache).
*
- * If a dentry was found and moved, then it is returned. Otherwise NULL
- * is returned. This matches the expected return value of ->lookup.
+ * When called on a directory inode, we must ensure that the inode only ever
+ * has one dentry. If a dentry is found, that is returned instead of
+ * allocating a new one.
*
+ * On successful return, the reference to the inode has been transferred
+ * to the dentry. In case of an error the reference on the inode is released.
+ * To make it easier to use in export operations a %NULL or IS_ERR inode may
+ * be passed in and the error will be propagated to the return value,
+ * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
*/
-struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
+struct dentry *d_obtain_alias(struct inode *inode)
{
- struct dentry *new = NULL;
-
- if (IS_ERR(inode))
- return ERR_CAST(inode);
+ return __d_obtain_alias(inode, 1);
+}
+EXPORT_SYMBOL(d_obtain_alias);
- if (inode && S_ISDIR(inode->i_mode)) {
- spin_lock(&inode->i_lock);
- new = __d_find_alias(inode, 1);
- if (new) {
- BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
- spin_unlock(&inode->i_lock);
- security_d_instantiate(new, inode);
- d_move(new, dentry);
- iput(inode);
- } else {
- /* already taking inode->i_lock, so d_add() by hand */
- __d_instantiate(dentry, inode);
- spin_unlock(&inode->i_lock);
- security_d_instantiate(dentry, inode);
- d_rehash(dentry);
- }
- } else
- d_add(dentry, inode);
- return new;
+/**
+ * d_obtain_root - find or allocate a dentry for a given inode
+ * @inode: inode to allocate the dentry for
+ *
+ * Obtain an IS_ROOT dentry for the root of a filesystem.
+ *
+ * We must ensure that directory inodes only ever have one dentry. If a
+ * dentry is found, that is returned instead of allocating a new one.
+ *
+ * On successful return, the reference to the inode has been transferred
+ * to the dentry. In case of an error the reference on the inode is
+ * released. A %NULL or IS_ERR inode may be passed in and will be the
+ * error will be propagate to the return value, with a %NULL @inode
+ * replaced by ERR_PTR(-ESTALE).
+ */
+struct dentry *d_obtain_root(struct inode *inode)
+{
+ return __d_obtain_alias(inode, 0);
}
-EXPORT_SYMBOL(d_splice_alias);
+EXPORT_SYMBOL(d_obtain_root);
/**
* d_add_ci - lookup or allocate new dentry with case-exact name
* if not go ahead and create it now.
*/
found = d_hash_and_lookup(dentry->d_parent, name);
- if (unlikely(IS_ERR(found)))
- goto err_out;
if (!found) {
new = d_alloc(dentry->d_parent, name);
if (!new) {
- found = ERR_PTR(-ENOMEM);
- goto err_out;
- }
-
- found = d_splice_alias(inode, new);
- if (found) {
- dput(new);
- return found;
- }
- return new;
- }
-
- /*
- * If a matching dentry exists, and it's not negative use it.
- *
- * Decrement the reference count to balance the iget() done
- * earlier on.
- */
- if (found->d_inode) {
- if (unlikely(found->d_inode != inode)) {
- /* This can't happen because bad inodes are unhashed. */
- BUG_ON(!is_bad_inode(inode));
- BUG_ON(!is_bad_inode(found->d_inode));
- }
- iput(inode);
- return found;
- }
-
- /*
- * Negative dentry: instantiate it unless the inode is a directory and
- * already has a dentry.
- */
- new = d_splice_alias(inode, found);
- if (new) {
- dput(found);
- found = new;
+ found = ERR_PTR(-ENOMEM);
+ } else {
+ found = d_splice_alias(inode, new);
+ if (found) {
+ dput(new);
+ return found;
+ }
+ return new;
+ }
}
- return found;
-
-err_out:
iput(inode);
return found;
}
* Do the slow-case of the dentry name compare.
*
* Unlike the dentry_cmp() function, we need to atomically
- * load the name, length and inode information, so that the
+ * load the name and length information, so that the
* filesystem can rely on them, and can use the 'name' and
* 'len' information without worrying about walking off the
* end of memory etc.
static noinline enum slow_d_compare slow_dentry_cmp(
const struct dentry *parent,
- struct inode *inode,
struct dentry *dentry,
unsigned int seq,
const struct qstr *name)
{
int tlen = dentry->d_name.len;
const char *tname = dentry->d_name.name;
- struct inode *i = dentry->d_inode;
if (read_seqcount_retry(&dentry->d_seq, seq)) {
cpu_relax();
return D_COMP_SEQRETRY;
}
- if (parent->d_op->d_compare(parent, inode,
- dentry, i,
- tlen, tname, name))
+ if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
return D_COMP_NOMATCH;
return D_COMP_OK;
}
* @parent: parent dentry
* @name: qstr of name we wish to find
* @seqp: returns d_seq value at the point where the dentry was found
- * @inode: returns dentry->d_inode when the inode was found valid.
* Returns: dentry, or NULL
*
* __d_lookup_rcu is the dcache lookup function for rcu-walk name
* without taking d_lock and checking d_seq sequence count against @seq
* returned here.
*
- * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
+ * A refcount may be taken on the found dentry with the d_rcu_to_refcount
* function.
*
* Alternatively, __d_lookup_rcu may be called again to look up the child of
*/
struct dentry *__d_lookup_rcu(const struct dentry *parent,
const struct qstr *name,
- unsigned *seqp, struct inode *inode)
+ unsigned *seqp)
{
u64 hashlen = name->hash_len;
const unsigned char *str = name->name;
seqretry:
/*
* The dentry sequence count protects us from concurrent
- * renames, and thus protects inode, parent and name fields.
+ * renames, and thus protects parent and name fields.
*
* The caller must perform a seqcount check in order
- * to do anything useful with the returned dentry,
- * including using the 'd_inode' pointer.
+ * to do anything useful with the returned dentry.
*
* NOTE! We do a "raw" seqcount_begin here. That means that
* we don't wait for the sequence count to stabilize if it
continue;
if (d_unhashed(dentry))
continue;
- *seqp = seq;
if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
if (dentry->d_name.hash != hashlen_hash(hashlen))
continue;
- switch (slow_dentry_cmp(parent, inode, dentry, seq, name)) {
+ *seqp = seq;
+ switch (slow_dentry_cmp(parent, dentry, seq, name)) {
case D_COMP_OK:
return dentry;
case D_COMP_NOMATCH:
if (dentry->d_name.hash_len != hashlen)
continue;
+ *seqp = seq;
if (!dentry_cmp(dentry, str, hashlen_len(hashlen)))
return dentry;
}
struct dentry *dentry;
unsigned seq;
- do {
- seq = read_seqbegin(&rename_lock);
- dentry = __d_lookup(parent, name);
- if (dentry)
+ do {
+ seq = read_seqbegin(&rename_lock);
+ dentry = __d_lookup(parent, name);
+ if (dentry)
break;
} while (read_seqretry(&rename_lock, seq));
return dentry;
if (parent->d_flags & DCACHE_OP_COMPARE) {
int tlen = dentry->d_name.len;
const char *tname = dentry->d_name.name;
- if (parent->d_op->d_compare(parent, parent->d_inode,
- dentry, dentry->d_inode,
- tlen, tname, name))
+ if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
goto next;
} else {
if (dentry->d_name.len != len)
goto next;
}
- dentry->d_count++;
+ dentry->d_lockref.count++;
found = dentry;
spin_unlock(&dentry->d_lock);
break;
*/
name->hash = full_name_hash(name->name, name->len);
if (dir->d_flags & DCACHE_OP_HASH) {
- int err = dir->d_op->d_hash(dir, dir->d_inode, name);
+ int err = dir->d_op->d_hash(dir, name);
if (unlikely(err < 0))
return ERR_PTR(err);
}
}
EXPORT_SYMBOL(d_hash_and_lookup);
-/**
- * d_validate - verify dentry provided from insecure source (deprecated)
- * @dentry: The dentry alleged to be valid child of @dparent
- * @dparent: The parent dentry (known to be valid)
- *
- * An insecure source has sent us a dentry, here we verify it and dget() it.
- * This is used by ncpfs in its readdir implementation.
- * Zero is returned in the dentry is invalid.
- *
- * This function is slow for big directories, and deprecated, do not use it.
- */
-int d_validate(struct dentry *dentry, struct dentry *dparent)
-{
- struct dentry *child;
-
- spin_lock(&dparent->d_lock);
- list_for_each_entry(child, &dparent->d_subdirs, d_child) {
- if (dentry == child) {
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- __dget_dlock(dentry);
- spin_unlock(&dentry->d_lock);
- spin_unlock(&dparent->d_lock);
- return 1;
- }
- }
- spin_unlock(&dparent->d_lock);
-
- return 0;
-}
-EXPORT_SYMBOL(d_validate);
-
/*
* When a file is deleted, we have two options:
* - turn this dentry into a negative dentry
spin_lock(&dentry->d_lock);
inode = dentry->d_inode;
isdir = S_ISDIR(inode->i_mode);
- if (dentry->d_count == 1) {
+ if (dentry->d_lockref.count == 1) {
if (!spin_trylock(&inode->i_lock)) {
spin_unlock(&dentry->d_lock);
cpu_relax();
{
BUG_ON(!d_unhashed(entry));
hlist_bl_lock(b);
- entry->d_flags |= DCACHE_RCUACCESS;
hlist_bl_add_head_rcu(&entry->d_hash, b);
hlist_bl_unlock(b);
}
}
EXPORT_SYMBOL(dentry_update_name_case);
-static void switch_names(struct dentry *dentry, struct dentry *target)
+static void swap_names(struct dentry *dentry, struct dentry *target)
{
- if (dname_external(target)) {
- if (dname_external(dentry)) {
+ if (unlikely(dname_external(target))) {
+ if (unlikely(dname_external(dentry))) {
/*
* Both external: swap the pointers
*/
target->d_name.name = target->d_iname;
}
} else {
- if (dname_external(dentry)) {
+ if (unlikely(dname_external(dentry))) {
/*
* dentry:external, target:internal. Give dentry's
* storage to target and make dentry internal
dentry->d_name.name = dentry->d_iname;
} else {
/*
- * Both are internal. Just copy target to dentry
+ * Both are internal.
*/
- memcpy(dentry->d_iname, target->d_name.name,
- target->d_name.len + 1);
- dentry->d_name.len = target->d_name.len;
- return;
+ unsigned int i;
+ BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
+ kmemcheck_mark_initialized(dentry->d_iname, DNAME_INLINE_LEN);
+ kmemcheck_mark_initialized(target->d_iname, DNAME_INLINE_LEN);
+ for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
+ swap(((long *) &dentry->d_iname)[i],
+ ((long *) &target->d_iname)[i]);
+ }
}
}
- swap(dentry->d_name.len, target->d_name.len);
+ swap(dentry->d_name.hash_len, target->d_name.hash_len);
+}
+
+static void copy_name(struct dentry *dentry, struct dentry *target)
+{
+ struct external_name *old_name = NULL;
+ if (unlikely(dname_external(dentry)))
+ old_name = external_name(dentry);
+ if (unlikely(dname_external(target))) {
+ atomic_inc(&external_name(target)->u.count);
+ dentry->d_name = target->d_name;
+ } else {
+ memcpy(dentry->d_iname, target->d_name.name,
+ target->d_name.len + 1);
+ dentry->d_name.name = dentry->d_iname;
+ dentry->d_name.hash_len = target->d_name.hash_len;
+ }
+ if (old_name && likely(atomic_dec_and_test(&old_name->u.count)))
+ kfree_rcu(old_name, u.head);
}
static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
}
}
-static void dentry_unlock_parents_for_move(struct dentry *dentry,
- struct dentry *target)
+static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
{
if (target->d_parent != dentry->d_parent)
spin_unlock(&dentry->d_parent->d_lock);
if (target->d_parent != target)
spin_unlock(&target->d_parent->d_lock);
+ spin_unlock(&target->d_lock);
+ spin_unlock(&dentry->d_lock);
}
/*
* When switching names, the actual string doesn't strictly have to
* be preserved in the target - because we're dropping the target
* anyway. As such, we can just do a simple memcpy() to copy over
- * the new name before we switch.
- *
- * Note that we have to be a lot more careful about getting the hash
- * switched - we have to switch the hash value properly even if it
- * then no longer matches the actual (corrupted) string of the target.
- * The hash value has to match the hash queue that the dentry is on..
+ * the new name before we switch, unless we are going to rehash
+ * it. Note that if we *do* unhash the target, we are not allowed
+ * to rehash it without giving it a new name/hash key - whether
+ * we swap or overwrite the names here, resulting name won't match
+ * the reality in filesystem; it's only there for d_path() purposes.
+ * Note that all of this is happening under rename_lock, so the
+ * any hash lookup seeing it in the middle of manipulations will
+ * be discarded anyway. So we do not care what happens to the hash
+ * key in that case.
*/
/*
* __d_move - move a dentry
* @dentry: entry to move
* @target: new dentry
+ * @exchange: exchange the two dentries
*
* Update the dcache to reflect the move of a file name. Negative
* dcache entries should not be moved in this way. Caller must hold
* rename_lock, the i_mutex of the source and target directories,
* and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
*/
-static void __d_move(struct dentry * dentry, struct dentry * target)
+static void __d_move(struct dentry *dentry, struct dentry *target,
+ bool exchange)
{
if (!dentry->d_inode)
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
dentry_lock_for_move(dentry, target);
write_seqcount_begin(&dentry->d_seq);
- write_seqcount_begin(&target->d_seq);
+ write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
__d_drop(dentry);
__d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
- /* Unhash the target: dput() will then get rid of it */
+ /*
+ * Unhash the target (d_delete() is not usable here). If exchanging
+ * the two dentries, then rehash onto the other's hash queue.
+ */
__d_drop(target);
-
- list_del(&dentry->d_child);
- list_del(&target->d_child);
+ if (exchange) {
+ __d_rehash(target,
+ d_hash(dentry->d_parent, dentry->d_name.hash));
+ }
/* Switch the names.. */
- switch_names(dentry, target);
- swap(dentry->d_name.hash, target->d_name.hash);
+ if (exchange)
+ swap_names(dentry, target);
+ else
+ copy_name(dentry, target);
- /* ... and switch the parents */
+ /* ... and switch them in the tree */
if (IS_ROOT(dentry)) {
+ /* splicing a tree */
+ dentry->d_flags |= DCACHE_RCUACCESS;
dentry->d_parent = target->d_parent;
target->d_parent = target;
- INIT_LIST_HEAD(&target->d_child);
+ list_del_init(&target->d_child);
+ list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
} else {
+ /* swapping two dentries */
swap(dentry->d_parent, target->d_parent);
-
- /* And add them back to the (new) parent lists */
- list_add(&target->d_child, &target->d_parent->d_subdirs);
+ list_move(&target->d_child, &target->d_parent->d_subdirs);
+ list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
+ if (exchange)
+ fsnotify_d_move(target);
+ fsnotify_d_move(dentry);
}
- list_add(&dentry->d_child, &dentry->d_parent->d_subdirs);
-
write_seqcount_end(&target->d_seq);
write_seqcount_end(&dentry->d_seq);
- dentry_unlock_parents_for_move(dentry, target);
- spin_unlock(&target->d_lock);
- fsnotify_d_move(dentry);
- spin_unlock(&dentry->d_lock);
+ dentry_unlock_for_move(dentry, target);
}
/*
void d_move(struct dentry *dentry, struct dentry *target)
{
write_seqlock(&rename_lock);
- __d_move(dentry, target);
+ __d_move(dentry, target, false);
write_sequnlock(&rename_lock);
}
EXPORT_SYMBOL(d_move);
+/*
+ * d_exchange - exchange two dentries
+ * @dentry1: first dentry
+ * @dentry2: second dentry
+ */
+void d_exchange(struct dentry *dentry1, struct dentry *dentry2)
+{
+ write_seqlock(&rename_lock);
+
+ WARN_ON(!dentry1->d_inode);
+ WARN_ON(!dentry2->d_inode);
+ WARN_ON(IS_ROOT(dentry1));
+ WARN_ON(IS_ROOT(dentry2));
+
+ __d_move(dentry1, dentry2, true);
+
+ write_sequnlock(&rename_lock);
+}
+
/**
* d_ancestor - search for an ancestor
* @p1: ancestor dentry
* This helper attempts to cope with remotely renamed directories
*
* It assumes that the caller is already holding
- * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
+ * dentry->d_parent->d_inode->i_mutex, and rename_lock
*
* Note: If ever the locking in lock_rename() changes, then please
* remember to update this too...
*/
-static struct dentry *__d_unalias(struct inode *inode,
+static int __d_unalias(struct inode *inode,
struct dentry *dentry, struct dentry *alias)
{
struct mutex *m1 = NULL, *m2 = NULL;
- struct dentry *ret = ERR_PTR(-EBUSY);
+ int ret = -ESTALE;
/* If alias and dentry share a parent, then no extra locks required */
if (alias->d_parent == dentry->d_parent)
goto out_err;
m2 = &alias->d_parent->d_inode->i_mutex;
out_unalias:
- if (likely(!d_mountpoint(alias))) {
- __d_move(alias, dentry);
- ret = alias;
- }
+ __d_move(alias, dentry, false);
+ ret = 0;
out_err:
- spin_unlock(&inode->i_lock);
if (m2)
mutex_unlock(m2);
if (m1)
return ret;
}
-/*
- * Prepare an anonymous dentry for life in the superblock's dentry tree as a
- * named dentry in place of the dentry to be replaced.
- * returns with anon->d_lock held!
- */
-static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
-{
- struct dentry *dparent;
-
- dentry_lock_for_move(anon, dentry);
-
- write_seqcount_begin(&dentry->d_seq);
- write_seqcount_begin(&anon->d_seq);
-
- dparent = dentry->d_parent;
-
- switch_names(dentry, anon);
- swap(dentry->d_name.hash, anon->d_name.hash);
-
- dentry->d_parent = dentry;
- list_del_init(&dentry->d_child);
- anon->d_parent = dparent;
- list_move(&anon->d_child, &dparent->d_subdirs);
-
- write_seqcount_end(&dentry->d_seq);
- write_seqcount_end(&anon->d_seq);
-
- dentry_unlock_parents_for_move(anon, dentry);
- spin_unlock(&dentry->d_lock);
-
- /* anon->d_lock still locked, returns locked */
- anon->d_flags &= ~DCACHE_DISCONNECTED;
-}
-
/**
- * d_materialise_unique - introduce an inode into the tree
- * @dentry: candidate dentry
- * @inode: inode to bind to the dentry, to which aliases may be attached
+ * d_splice_alias - splice a disconnected dentry into the tree if one exists
+ * @inode: the inode which may have a disconnected dentry
+ * @dentry: a negative dentry which we want to point to the inode.
+ *
+ * If inode is a directory and has an IS_ROOT alias, then d_move that in
+ * place of the given dentry and return it, else simply d_add the inode
+ * to the dentry and return NULL.
+ *
+ * If a non-IS_ROOT directory is found, the filesystem is corrupt, and
+ * we should error out: directories can't have multiple aliases.
+ *
+ * This is needed in the lookup routine of any filesystem that is exportable
+ * (via knfsd) so that we can build dcache paths to directories effectively.
+ *
+ * If a dentry was found and moved, then it is returned. Otherwise NULL
+ * is returned. This matches the expected return value of ->lookup.
*
- * Introduces an dentry into the tree, substituting an extant disconnected
- * root directory alias in its place if there is one. Caller must hold the
- * i_mutex of the parent directory.
+ * Cluster filesystems may call this function with a negative, hashed dentry.
+ * In that case, we know that the inode will be a regular file, and also this
+ * will only occur during atomic_open. So we need to check for the dentry
+ * being already hashed only in the final case.
*/
-struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
+struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
{
- struct dentry *actual;
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
BUG_ON(!d_unhashed(dentry));
if (!inode) {
- actual = dentry;
__d_instantiate(dentry, NULL);
- d_rehash(actual);
- goto out_nolock;
+ goto out;
}
-
spin_lock(&inode->i_lock);
-
if (S_ISDIR(inode->i_mode)) {
- struct dentry *alias;
-
- /* Does an aliased dentry already exist? */
- alias = __d_find_alias(inode, 0);
- if (alias) {
- actual = alias;
+ struct dentry *new = __d_find_any_alias(inode);
+ if (unlikely(new)) {
+ /* The reference to new ensures it remains an alias */
+ spin_unlock(&inode->i_lock);
write_seqlock(&rename_lock);
-
- if (d_ancestor(alias, dentry)) {
- /* Check for loops */
- actual = ERR_PTR(-ELOOP);
- spin_unlock(&inode->i_lock);
- } else if (IS_ROOT(alias)) {
- /* Is this an anonymous mountpoint that we
- * could splice into our tree? */
- __d_materialise_dentry(dentry, alias);
+ if (unlikely(d_ancestor(new, dentry))) {
write_sequnlock(&rename_lock);
- __d_drop(alias);
- goto found;
+ dput(new);
+ new = ERR_PTR(-ELOOP);
+ pr_warn_ratelimited(
+ "VFS: Lookup of '%s' in %s %s"
+ " would have caused loop\n",
+ dentry->d_name.name,
+ inode->i_sb->s_type->name,
+ inode->i_sb->s_id);
+ } else if (!IS_ROOT(new)) {
+ int err = __d_unalias(inode, dentry, new);
+ write_sequnlock(&rename_lock);
+ if (err) {
+ dput(new);
+ new = ERR_PTR(err);
+ }
} else {
- /* Nope, but we must(!) avoid directory
- * aliasing. This drops inode->i_lock */
- actual = __d_unalias(inode, dentry, alias);
- }
- write_sequnlock(&rename_lock);
- if (IS_ERR(actual)) {
- if (PTR_ERR(actual) == -ELOOP)
- pr_warn_ratelimited(
- "VFS: Lookup of '%s' in %s %s"
- " would have caused loop\n",
- dentry->d_name.name,
- inode->i_sb->s_type->name,
- inode->i_sb->s_id);
- dput(alias);
+ __d_move(new, dentry, false);
+ write_sequnlock(&rename_lock);
+ security_d_instantiate(new, inode);
}
- goto out_nolock;
+ iput(inode);
+ return new;
}
}
-
- /* Add a unique reference */
- actual = __d_instantiate_unique(dentry, inode);
- if (!actual)
- actual = dentry;
- else
- BUG_ON(!d_unhashed(actual));
-
- spin_lock(&actual->d_lock);
-found:
- _d_rehash(actual);
- spin_unlock(&actual->d_lock);
+ /* already taking inode->i_lock, so d_add() by hand */
+ __d_instantiate(dentry, inode);
spin_unlock(&inode->i_lock);
-out_nolock:
- if (actual == dentry) {
- security_d_instantiate(dentry, inode);
- return NULL;
- }
-
- iput(inode);
- return actual;
+out:
+ security_d_instantiate(dentry, inode);
+ d_rehash(dentry);
+ return NULL;
}
-EXPORT_SYMBOL_GPL(d_materialise_unique);
+EXPORT_SYMBOL(d_splice_alias);
static int prepend(char **buffer, int *buflen, const char *str, int namelen)
{
return 0;
}
+/**
+ * prepend_name - prepend a pathname in front of current buffer pointer
+ * @buffer: buffer pointer
+ * @buflen: allocated length of the buffer
+ * @name: name string and length qstr structure
+ *
+ * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to
+ * make sure that either the old or the new name pointer and length are
+ * fetched. However, there may be mismatch between length and pointer.
+ * The length cannot be trusted, we need to copy it byte-by-byte until
+ * the length is reached or a null byte is found. It also prepends "/" at
+ * the beginning of the name. The sequence number check at the caller will
+ * retry it again when a d_move() does happen. So any garbage in the buffer
+ * due to mismatched pointer and length will be discarded.
+ *
+ * Data dependency barrier is needed to make sure that we see that terminating
+ * NUL. Alpha strikes again, film at 11...
+ */
static int prepend_name(char **buffer, int *buflen, struct qstr *name)
{
- return prepend(buffer, buflen, name->name, name->len);
+ const char *dname = ACCESS_ONCE(name->name);
+ u32 dlen = ACCESS_ONCE(name->len);
+ char *p;
+
+ smp_read_barrier_depends();
+
+ *buflen -= dlen + 1;
+ if (*buflen < 0)
+ return -ENAMETOOLONG;
+ p = *buffer -= dlen + 1;
+ *p++ = '/';
+ while (dlen--) {
+ char c = *dname++;
+ if (!c)
+ break;
+ *p++ = c;
+ }
+ return 0;
}
/**
* @buffer: pointer to the end of the buffer
* @buflen: pointer to buffer length
*
- * Caller holds the rename_lock.
+ * The function will first try to write out the pathname without taking any
+ * lock other than the RCU read lock to make sure that dentries won't go away.
+ * It only checks the sequence number of the global rename_lock as any change
+ * in the dentry's d_seq will be preceded by changes in the rename_lock
+ * sequence number. If the sequence number had been changed, it will restart
+ * the whole pathname back-tracing sequence again by taking the rename_lock.
+ * In this case, there is no need to take the RCU read lock as the recursive
+ * parent pointer references will keep the dentry chain alive as long as no
+ * rename operation is performed.
*/
static int prepend_path(const struct path *path,
const struct path *root,
char **buffer, int *buflen)
{
- struct dentry *dentry = path->dentry;
- struct vfsmount *vfsmnt = path->mnt;
- struct mount *mnt = real_mount(vfsmnt);
- bool slash = false;
+ struct dentry *dentry;
+ struct vfsmount *vfsmnt;
+ struct mount *mnt;
int error = 0;
+ unsigned seq, m_seq = 0;
+ char *bptr;
+ int blen;
+ rcu_read_lock();
+restart_mnt:
+ read_seqbegin_or_lock(&mount_lock, &m_seq);
+ seq = 0;
+ rcu_read_lock();
+restart:
+ bptr = *buffer;
+ blen = *buflen;
+ error = 0;
+ dentry = path->dentry;
+ vfsmnt = path->mnt;
+ mnt = real_mount(vfsmnt);
+ read_seqbegin_or_lock(&rename_lock, &seq);
while (dentry != root->dentry || vfsmnt != root->mnt) {
struct dentry * parent;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
+ struct mount *parent = ACCESS_ONCE(mnt->mnt_parent);
+ /* Escaped? */
+ if (dentry != vfsmnt->mnt_root) {
+ bptr = *buffer;
+ blen = *buflen;
+ error = 3;
+ break;
+ }
/* Global root? */
- if (!mnt_has_parent(mnt))
- goto global_root;
- dentry = mnt->mnt_mountpoint;
- mnt = mnt->mnt_parent;
- vfsmnt = &mnt->mnt;
- continue;
+ if (mnt != parent) {
+ dentry = ACCESS_ONCE(mnt->mnt_mountpoint);
+ mnt = parent;
+ vfsmnt = &mnt->mnt;
+ continue;
+ }
+ if (!error)
+ error = is_mounted(vfsmnt) ? 1 : 2;
+ break;
}
parent = dentry->d_parent;
prefetch(parent);
- spin_lock(&dentry->d_lock);
- error = prepend_name(buffer, buflen, &dentry->d_name);
- spin_unlock(&dentry->d_lock);
- if (!error)
- error = prepend(buffer, buflen, "/", 1);
+ error = prepend_name(&bptr, &blen, &dentry->d_name);
if (error)
break;
- slash = true;
dentry = parent;
}
+ if (!(seq & 1))
+ rcu_read_unlock();
+ if (need_seqretry(&rename_lock, seq)) {
+ seq = 1;
+ goto restart;
+ }
+ done_seqretry(&rename_lock, seq);
- if (!error && !slash)
- error = prepend(buffer, buflen, "/", 1);
-
- return error;
+ if (!(m_seq & 1))
+ rcu_read_unlock();
+ if (need_seqretry(&mount_lock, m_seq)) {
+ m_seq = 1;
+ goto restart_mnt;
+ }
+ done_seqretry(&mount_lock, m_seq);
-global_root:
- if (!slash)
- error = prepend(buffer, buflen, "/", 1);
- if (!error)
- error = is_mounted(vfsmnt) ? 1 : 2;
+ if (error >= 0 && bptr == *buffer) {
+ if (--blen < 0)
+ error = -ENAMETOOLONG;
+ else
+ *--bptr = '/';
+ }
+ *buffer = bptr;
+ *buflen = blen;
return error;
}
int error;
prepend(&res, &buflen, "\0", 1);
- br_read_lock(&vfsmount_lock);
- write_seqlock(&rename_lock);
error = prepend_path(path, root, &res, &buflen);
- write_sequnlock(&rename_lock);
- br_read_unlock(&vfsmount_lock);
if (error < 0)
return ERR_PTR(error);
int error;
prepend(&res, &buflen, "\0", 1);
- br_read_lock(&vfsmount_lock);
- write_seqlock(&rename_lock);
error = prepend_path(path, &root, &res, &buflen);
- write_sequnlock(&rename_lock);
- br_read_unlock(&vfsmount_lock);
if (error > 1)
error = -EINVAL;
return ERR_PTR(error);
return res;
}
+EXPORT_SYMBOL(d_absolute_path);
/*
* same as __d_path but appends "(deleted)" for unlinked files.
return prepend(buffer, buflen, "(unreachable)", 13);
}
+static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
+{
+ unsigned seq;
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ *root = fs->root;
+ } while (read_seqcount_retry(&fs->seq, seq));
+}
+
/**
* d_path - return the path of a dentry
* @path: path to report
(!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root))
return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
- get_fs_root(current->fs, &root);
- br_read_lock(&vfsmount_lock);
- write_seqlock(&rename_lock);
+ rcu_read_lock();
+ get_fs_root_rcu(current->fs, &root);
error = path_with_deleted(path, &root, &res, &buflen);
- write_sequnlock(&rename_lock);
- br_read_unlock(&vfsmount_lock);
+ rcu_read_unlock();
+
if (error < 0)
res = ERR_PTR(error);
- path_put(&root);
return res;
}
EXPORT_SYMBOL(d_path);
char *end = buffer + buflen;
/* these dentries are never renamed, so d_lock is not needed */
if (prepend(&end, &buflen, " (deleted)", 11) ||
- prepend_name(&end, &buflen, &dentry->d_name) ||
- prepend(&end, &buflen, "/", 1))
+ prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) ||
+ prepend(&end, &buflen, "/", 1))
end = ERR_PTR(-ENAMETOOLONG);
return end;
}
+EXPORT_SYMBOL(simple_dname);
/*
* Write full pathname from the root of the filesystem into the buffer.
*/
-static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
+static char *__dentry_path(struct dentry *d, char *buf, int buflen)
{
- char *end = buf + buflen;
- char *retval;
+ struct dentry *dentry;
+ char *end, *retval;
+ int len, seq = 0;
+ int error = 0;
- prepend(&end, &buflen, "\0", 1);
- if (buflen < 1)
+ if (buflen < 2)
goto Elong;
+
+ rcu_read_lock();
+restart:
+ dentry = d;
+ end = buf + buflen;
+ len = buflen;
+ prepend(&end, &len, "\0", 1);
/* Get '/' right */
retval = end-1;
*retval = '/';
-
+ read_seqbegin_or_lock(&rename_lock, &seq);
while (!IS_ROOT(dentry)) {
struct dentry *parent = dentry->d_parent;
- int error;
prefetch(parent);
- spin_lock(&dentry->d_lock);
- error = prepend_name(&end, &buflen, &dentry->d_name);
- spin_unlock(&dentry->d_lock);
- if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
- goto Elong;
+ error = prepend_name(&end, &len, &dentry->d_name);
+ if (error)
+ break;
retval = end;
dentry = parent;
}
+ if (!(seq & 1))
+ rcu_read_unlock();
+ if (need_seqretry(&rename_lock, seq)) {
+ seq = 1;
+ goto restart;
+ }
+ done_seqretry(&rename_lock, seq);
+ if (error)
+ goto Elong;
return retval;
Elong:
return ERR_PTR(-ENAMETOOLONG);
char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
{
- char *retval;
-
- write_seqlock(&rename_lock);
- retval = __dentry_path(dentry, buf, buflen);
- write_sequnlock(&rename_lock);
-
- return retval;
+ return __dentry_path(dentry, buf, buflen);
}
EXPORT_SYMBOL(dentry_path_raw);
char *p = NULL;
char *retval;
- write_seqlock(&rename_lock);
if (d_unlinked(dentry)) {
p = buf + buflen;
if (prepend(&p, &buflen, "//deleted", 10) != 0)
buflen++;
}
retval = __dentry_path(dentry, buf, buflen);
- write_sequnlock(&rename_lock);
if (!IS_ERR(retval) && p)
*p = '/'; /* restore '/' overriden with '\0' */
return retval;
return ERR_PTR(-ENAMETOOLONG);
}
+static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root,
+ struct path *pwd)
+{
+ unsigned seq;
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ *root = fs->root;
+ *pwd = fs->pwd;
+ } while (read_seqcount_retry(&fs->seq, seq));
+}
+
/*
* NOTE! The user-level library version returns a
* character pointer. The kernel system call just
{
int error;
struct path pwd, root;
- char *page = (char *) __get_free_page(GFP_USER);
+ char *page = __getname();
if (!page)
return -ENOMEM;
- get_fs_root_and_pwd(current->fs, &root, &pwd);
+ rcu_read_lock();
+ get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
error = -ENOENT;
- br_read_lock(&vfsmount_lock);
- write_seqlock(&rename_lock);
if (!d_unlinked(pwd.dentry)) {
unsigned long len;
- char *cwd = page + PAGE_SIZE;
- int buflen = PAGE_SIZE;
+ char *cwd = page + PATH_MAX;
+ int buflen = PATH_MAX;
prepend(&cwd, &buflen, "\0", 1);
error = prepend_path(&pwd, &root, &cwd, &buflen);
- write_sequnlock(&rename_lock);
- br_read_unlock(&vfsmount_lock);
+ rcu_read_unlock();
if (error < 0)
goto out;
}
error = -ERANGE;
- len = PAGE_SIZE + page - cwd;
+ len = PATH_MAX + page - cwd;
if (len <= size) {
error = len;
if (copy_to_user(buf, cwd, len))
error = -EFAULT;
}
} else {
- write_sequnlock(&rename_lock);
- br_read_unlock(&vfsmount_lock);
+ rcu_read_unlock();
}
out:
- path_put(&pwd);
- path_put(&root);
- free_page((unsigned long) page);
+ __putname(page);
return error;
}
return result;
}
-void d_genocide(struct dentry *root)
+static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
{
- struct dentry *this_parent;
- struct list_head *next;
- unsigned seq;
- int locked = 0;
-
- seq = read_seqbegin(&rename_lock);
-again:
- this_parent = root;
- spin_lock(&this_parent->d_lock);
-repeat:
- next = this_parent->d_subdirs.next;
-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;
+ struct dentry *root = data;
+ if (dentry != root) {
+ if (d_unhashed(dentry) || !dentry->d_inode)
+ return D_WALK_SKIP;
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- if (d_unhashed(dentry) || !dentry->d_inode) {
- spin_unlock(&dentry->d_lock);
- continue;
- }
- if (!list_empty(&dentry->d_subdirs)) {
- spin_unlock(&this_parent->d_lock);
- spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
- this_parent = dentry;
- spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
- goto repeat;
- }
if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
dentry->d_flags |= DCACHE_GENOCIDE;
- dentry->d_count--;
- }
- spin_unlock(&dentry->d_lock);
- }
- rcu_read_lock();
-ascend:
- if (this_parent != root) {
- struct dentry *child = this_parent;
- if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
- this_parent->d_flags |= DCACHE_GENOCIDE;
- this_parent->d_count--;
+ dentry->d_lockref.count--;
}
- this_parent = child->d_parent;
-
- spin_unlock(&child->d_lock);
- spin_lock(&this_parent->d_lock);
-
- /* might go back up the wrong parent if we have had a rename. */
- if (!locked && read_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;
}
- if (!locked && read_seqretry(&rename_lock, seq))
- goto rename_retry;
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
- if (locked)
- write_sequnlock(&rename_lock);
- return;
-
-rename_retry:
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
- if (locked)
- goto again;
- locked = 1;
- write_seqlock(&rename_lock);
- goto again;
+ return D_WALK_CONTINUE;
}
-/**
- * find_inode_number - check for dentry with name
- * @dir: directory to check
- * @name: Name to find.
- *
- * Check whether a dentry already exists for the given name,
- * and return the inode number if it has an inode. Otherwise
- * 0 is returned.
- *
- * This routine is used to post-process directory listings for
- * filesystems using synthetic inode numbers, and is necessary
- * to keep getcwd() working.
- */
-
-ino_t find_inode_number(struct dentry *dir, struct qstr *name)
+void d_genocide(struct dentry *parent)
{
- struct dentry * dentry;
- ino_t ino = 0;
+ d_walk(parent, parent, d_genocide_kill, NULL);
+}
- dentry = d_hash_and_lookup(dir, name);
- if (!IS_ERR_OR_NULL(dentry)) {
- if (dentry->d_inode)
- ino = dentry->d_inode->i_ino;
- dput(dentry);
- }
- return ino;
+void d_tmpfile(struct dentry *dentry, struct inode *inode)
+{
+ inode_dec_link_count(inode);
+ BUG_ON(dentry->d_name.name != dentry->d_iname ||
+ !hlist_unhashed(&dentry->d_u.d_alias) ||
+ !d_unlinked(dentry));
+ spin_lock(&dentry->d_parent->d_lock);
+ spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+ dentry->d_name.len = sprintf(dentry->d_iname, "#%llu",
+ (unsigned long long)inode->i_ino);
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&dentry->d_parent->d_lock);
+ d_instantiate(dentry, inode);
}
-EXPORT_SYMBOL(find_inode_number);
+EXPORT_SYMBOL(d_tmpfile);
static __initdata unsigned long dhash_entries;
static int __init set_dhash_entries(char *str)
inode_init_early();
}
-void __init vfs_caches_init(unsigned long mempages)
+void __init vfs_caches_init(void)
{
- unsigned long reserve;
-
- /* Base hash sizes on available memory, with a reserve equal to
- 150% of current kernel size */
-
- reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
- mempages -= reserve;
-
names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
dcache_init();
inode_init();
- files_init(mempages);
+ files_init();
+ files_maxfiles_init();
mnt_init();
bdev_cache_init();
chrdev_init();
projects / firefly-linux-kernel-4.4.55.git / blobdiff