summaryrefslogtreecommitdiff
path: root/fs/dcache.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/dcache.c')
-rw-r--r--fs/dcache.c283
1 files changed, 246 insertions, 37 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index d5ecc6e477da..ad4a542e9bab 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -111,6 +111,17 @@ static inline struct hlist_bl_head *d_hash(const struct dentry *parent,
return dentry_hashtable + hash_32(hash, d_hash_shift);
}
+#define IN_LOOKUP_SHIFT 10
+static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT];
+
+static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent,
+ unsigned int hash)
+{
+ hash += (unsigned long) parent / L1_CACHE_BYTES;
+ return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT);
+}
+
+
/* Statistics gathering. */
struct dentry_stat_t dentry_stat = {
.age_limit = 45,
@@ -761,6 +772,8 @@ repeat:
/* Slow case: now with the dentry lock held */
rcu_read_unlock();
+ WARN_ON(d_in_lookup(dentry));
+
/* Unreachable? Get rid of it */
if (unlikely(d_unhashed(dentry)))
goto kill_it;
@@ -1558,7 +1571,11 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
* be overwriting an internal NUL character
*/
dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
- if (name->len > DNAME_INLINE_LEN-1) {
+ if (unlikely(!name)) {
+ static const struct qstr anon = QSTR_INIT("/", 1);
+ name = &anon;
+ dname = dentry->d_iname;
+ } else if (name->len > DNAME_INLINE_LEN-1) {
size_t size = offsetof(struct external_name, name[1]);
struct external_name *p = kmalloc(size + name->len,
GFP_KERNEL_ACCOUNT);
@@ -1653,8 +1670,7 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name)
struct qstr q;
q.name = name;
- q.len = strlen(name);
- q.hash = full_name_hash(q.name, q.len);
+ q.hash_len = hashlen_string(name);
return d_alloc(parent, &q);
}
EXPORT_SYMBOL(d_alloc_name);
@@ -1746,6 +1762,7 @@ type_determined:
static void __d_instantiate(struct dentry *dentry, struct inode *inode)
{
unsigned add_flags = d_flags_for_inode(inode);
+ WARN_ON(d_in_lookup(dentry));
spin_lock(&dentry->d_lock);
hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
@@ -1775,11 +1792,11 @@ void d_instantiate(struct dentry *entry, struct inode * inode)
{
BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
if (inode) {
+ security_d_instantiate(entry, inode);
spin_lock(&inode->i_lock);
__d_instantiate(entry, inode);
spin_unlock(&inode->i_lock);
}
- security_d_instantiate(entry, inode);
}
EXPORT_SYMBOL(d_instantiate);
@@ -1796,6 +1813,7 @@ int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode)
{
BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
+ security_d_instantiate(entry, inode);
spin_lock(&inode->i_lock);
if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) {
spin_unlock(&inode->i_lock);
@@ -1804,7 +1822,6 @@ int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode)
}
__d_instantiate(entry, inode);
spin_unlock(&inode->i_lock);
- security_d_instantiate(entry, inode);
return 0;
}
@@ -1815,9 +1832,7 @@ struct dentry *d_make_root(struct inode *root_inode)
struct dentry *res = NULL;
if (root_inode) {
- static const struct qstr name = QSTR_INIT("/", 1);
-
- res = __d_alloc(root_inode->i_sb, &name);
+ res = __d_alloc(root_inode->i_sb, NULL);
if (res)
d_instantiate(res, root_inode);
else
@@ -1858,7 +1873,6 @@ EXPORT_SYMBOL(d_find_any_alias);
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;
@@ -1872,12 +1886,13 @@ static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected)
if (res)
goto out_iput;
- tmp = __d_alloc(inode->i_sb, &anonstring);
+ tmp = __d_alloc(inode->i_sb, NULL);
if (!tmp) {
res = ERR_PTR(-ENOMEM);
goto out_iput;
}
+ security_d_instantiate(tmp, inode);
spin_lock(&inode->i_lock);
res = __d_find_any_alias(inode);
if (res) {
@@ -1900,13 +1915,10 @@ static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected)
hlist_bl_unlock(&tmp->d_sb->s_anon);
spin_unlock(&tmp->d_lock);
spin_unlock(&inode->i_lock);
- security_d_instantiate(tmp, inode);
return tmp;
out_iput:
- if (res && !IS_ERR(res))
- security_d_instantiate(res, inode);
iput(inode);
return res;
}
@@ -1975,28 +1987,36 @@ EXPORT_SYMBOL(d_obtain_root);
struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
struct qstr *name)
{
- struct dentry *found;
- struct dentry *new;
+ struct dentry *found, *res;
/*
* First check if a dentry matching the name already exists,
* if not go ahead and create it now.
*/
found = d_hash_and_lookup(dentry->d_parent, name);
- if (!found) {
- new = d_alloc(dentry->d_parent, name);
- if (!new) {
- found = ERR_PTR(-ENOMEM);
- } else {
- found = d_splice_alias(inode, new);
- if (found) {
- dput(new);
- return found;
- }
- return new;
+ if (found) {
+ iput(inode);
+ return found;
+ }
+ if (d_in_lookup(dentry)) {
+ found = d_alloc_parallel(dentry->d_parent, name,
+ dentry->d_wait);
+ if (IS_ERR(found) || !d_in_lookup(found)) {
+ iput(inode);
+ return found;
}
+ } else {
+ found = d_alloc(dentry->d_parent, name);
+ if (!found) {
+ iput(inode);
+ return ERR_PTR(-ENOMEM);
+ }
+ }
+ res = d_splice_alias(inode, found);
+ if (res) {
+ dput(found);
+ return res;
}
- iput(inode);
return found;
}
EXPORT_SYMBOL(d_add_ci);
@@ -2363,17 +2383,194 @@ void d_rehash(struct dentry * entry)
}
EXPORT_SYMBOL(d_rehash);
+static inline unsigned start_dir_add(struct inode *dir)
+{
+
+ for (;;) {
+ unsigned n = dir->i_dir_seq;
+ if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
+ return n;
+ cpu_relax();
+ }
+}
+
+static inline void end_dir_add(struct inode *dir, unsigned n)
+{
+ smp_store_release(&dir->i_dir_seq, n + 2);
+}
+
+static void d_wait_lookup(struct dentry *dentry)
+{
+ if (d_in_lookup(dentry)) {
+ DECLARE_WAITQUEUE(wait, current);
+ add_wait_queue(dentry->d_wait, &wait);
+ do {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ spin_unlock(&dentry->d_lock);
+ schedule();
+ spin_lock(&dentry->d_lock);
+ } while (d_in_lookup(dentry));
+ }
+}
+
+struct dentry *d_alloc_parallel(struct dentry *parent,
+ const struct qstr *name,
+ wait_queue_head_t *wq)
+{
+ unsigned int len = name->len;
+ unsigned int hash = name->hash;
+ const unsigned char *str = name->name;
+ struct hlist_bl_head *b = in_lookup_hash(parent, hash);
+ struct hlist_bl_node *node;
+ struct dentry *new = d_alloc(parent, name);
+ struct dentry *dentry;
+ unsigned seq, r_seq, d_seq;
+
+ if (unlikely(!new))
+ return ERR_PTR(-ENOMEM);
+
+retry:
+ rcu_read_lock();
+ seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1;
+ r_seq = read_seqbegin(&rename_lock);
+ dentry = __d_lookup_rcu(parent, name, &d_seq);
+ if (unlikely(dentry)) {
+ if (!lockref_get_not_dead(&dentry->d_lockref)) {
+ rcu_read_unlock();
+ goto retry;
+ }
+ if (read_seqcount_retry(&dentry->d_seq, d_seq)) {
+ rcu_read_unlock();
+ dput(dentry);
+ goto retry;
+ }
+ rcu_read_unlock();
+ dput(new);
+ return dentry;
+ }
+ if (unlikely(read_seqretry(&rename_lock, r_seq))) {
+ rcu_read_unlock();
+ goto retry;
+ }
+ hlist_bl_lock(b);
+ if (unlikely(parent->d_inode->i_dir_seq != seq)) {
+ hlist_bl_unlock(b);
+ rcu_read_unlock();
+ goto retry;
+ }
+ rcu_read_unlock();
+ /*
+ * No changes for the parent since the beginning of d_lookup().
+ * Since all removals from the chain happen with hlist_bl_lock(),
+ * any potential in-lookup matches are going to stay here until
+ * we unlock the chain. All fields are stable in everything
+ * we encounter.
+ */
+ hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) {
+ if (dentry->d_name.hash != hash)
+ continue;
+ if (dentry->d_parent != parent)
+ continue;
+ if (d_unhashed(dentry))
+ continue;
+ 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, dentry, tlen, tname, name))
+ continue;
+ } else {
+ if (dentry->d_name.len != len)
+ continue;
+ if (dentry_cmp(dentry, str, len))
+ continue;
+ }
+ dget(dentry);
+ hlist_bl_unlock(b);
+ /* somebody is doing lookup for it right now; wait for it */
+ spin_lock(&dentry->d_lock);
+ d_wait_lookup(dentry);
+ /*
+ * it's not in-lookup anymore; in principle we should repeat
+ * everything from dcache lookup, but it's likely to be what
+ * d_lookup() would've found anyway. If it is, just return it;
+ * otherwise we really have to repeat the whole thing.
+ */
+ if (unlikely(dentry->d_name.hash != hash))
+ goto mismatch;
+ if (unlikely(dentry->d_parent != parent))
+ goto mismatch;
+ if (unlikely(d_unhashed(dentry)))
+ goto mismatch;
+ 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, dentry, tlen, tname, name))
+ goto mismatch;
+ } else {
+ if (unlikely(dentry->d_name.len != len))
+ goto mismatch;
+ if (unlikely(dentry_cmp(dentry, str, len)))
+ goto mismatch;
+ }
+ /* OK, it *is* a hashed match; return it */
+ spin_unlock(&dentry->d_lock);
+ dput(new);
+ return dentry;
+ }
+ /* we can't take ->d_lock here; it's OK, though. */
+ new->d_flags |= DCACHE_PAR_LOOKUP;
+ new->d_wait = wq;
+ hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b);
+ hlist_bl_unlock(b);
+ return new;
+mismatch:
+ spin_unlock(&dentry->d_lock);
+ dput(dentry);
+ goto retry;
+}
+EXPORT_SYMBOL(d_alloc_parallel);
+
+void __d_lookup_done(struct dentry *dentry)
+{
+ struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent,
+ dentry->d_name.hash);
+ hlist_bl_lock(b);
+ dentry->d_flags &= ~DCACHE_PAR_LOOKUP;
+ __hlist_bl_del(&dentry->d_u.d_in_lookup_hash);
+ wake_up_all(dentry->d_wait);
+ dentry->d_wait = NULL;
+ hlist_bl_unlock(b);
+ INIT_HLIST_NODE(&dentry->d_u.d_alias);
+ INIT_LIST_HEAD(&dentry->d_lru);
+}
+EXPORT_SYMBOL(__d_lookup_done);
/* inode->i_lock held if inode is non-NULL */
static inline void __d_add(struct dentry *dentry, struct inode *inode)
{
+ struct inode *dir = NULL;
+ unsigned n;
+ spin_lock(&dentry->d_lock);
+ if (unlikely(d_in_lookup(dentry))) {
+ dir = dentry->d_parent->d_inode;
+ n = start_dir_add(dir);
+ __d_lookup_done(dentry);
+ }
if (inode) {
- __d_instantiate(dentry, inode);
+ unsigned add_flags = d_flags_for_inode(inode);
+ hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
+ raw_write_seqcount_begin(&dentry->d_seq);
+ __d_set_inode_and_type(dentry, inode, add_flags);
+ raw_write_seqcount_end(&dentry->d_seq);
+ __fsnotify_d_instantiate(dentry);
+ }
+ _d_rehash(dentry);
+ if (dir)
+ end_dir_add(dir, n);
+ spin_unlock(&dentry->d_lock);
+ if (inode)
spin_unlock(&inode->i_lock);
- }
- security_d_instantiate(dentry, inode);
- d_rehash(dentry);
}
/**
@@ -2387,8 +2584,10 @@ static inline void __d_add(struct dentry *dentry, struct inode *inode)
void d_add(struct dentry *entry, struct inode *inode)
{
- if (inode)
+ if (inode) {
+ security_d_instantiate(entry, inode);
spin_lock(&inode->i_lock);
+ }
__d_add(entry, inode);
}
EXPORT_SYMBOL(d_add);
@@ -2598,6 +2797,8 @@ static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
static void __d_move(struct dentry *dentry, struct dentry *target,
bool exchange)
{
+ struct inode *dir = NULL;
+ unsigned n;
if (!dentry->d_inode)
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
@@ -2605,6 +2806,11 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
BUG_ON(d_ancestor(target, dentry));
dentry_lock_for_move(dentry, target);
+ if (unlikely(d_in_lookup(target))) {
+ dir = target->d_parent->d_inode;
+ n = start_dir_add(dir);
+ __d_lookup_done(target);
+ }
write_seqcount_begin(&dentry->d_seq);
write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
@@ -2654,6 +2860,8 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
write_seqcount_end(&target->d_seq);
write_seqcount_end(&dentry->d_seq);
+ if (dir)
+ end_dir_add(dir, n);
dentry_unlock_for_move(dentry, target);
}
@@ -2724,7 +2932,8 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
static int __d_unalias(struct inode *inode,
struct dentry *dentry, struct dentry *alias)
{
- struct mutex *m1 = NULL, *m2 = NULL;
+ struct mutex *m1 = NULL;
+ struct rw_semaphore *m2 = NULL;
int ret = -ESTALE;
/* If alias and dentry share a parent, then no extra locks required */
@@ -2735,15 +2944,15 @@ static int __d_unalias(struct inode *inode,
if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
goto out_err;
m1 = &dentry->d_sb->s_vfs_rename_mutex;
- if (!inode_trylock(alias->d_parent->d_inode))
+ if (!inode_trylock_shared(alias->d_parent->d_inode))
goto out_err;
- m2 = &alias->d_parent->d_inode->i_mutex;
+ m2 = &alias->d_parent->d_inode->i_rwsem;
out_unalias:
__d_move(alias, dentry, false);
ret = 0;
out_err:
if (m2)
- mutex_unlock(m2);
+ up_read(m2);
if (m1)
mutex_unlock(m1);
return ret;
@@ -2782,6 +2991,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
if (!inode)
goto out;
+ security_d_instantiate(dentry, inode);
spin_lock(&inode->i_lock);
if (S_ISDIR(inode->i_mode)) {
struct dentry *new = __d_find_any_alias(inode);
@@ -2809,7 +3019,6 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
} else {
__d_move(new, dentry, false);
write_sequnlock(&rename_lock);
- security_d_instantiate(new, inode);
}
iput(inode);
return new;
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-23 15:08:12 +0300