static struct hlist_bl_head *dentry_hashtable __read_mostly;
-static inline struct hlist_bl_head *d_hash(const struct dentry *parent,
- unsigned int hash)
+static inline struct hlist_bl_head *d_hash(unsigned int hash)
{
- hash += (unsigned long) parent / L1_CACHE_BYTES;
- return dentry_hashtable + hash_32(hash, d_hash_shift);
+ return dentry_hashtable + (hash >> (32 - d_hash_shift));
}
#define IN_LOOKUP_SHIFT 10
static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount)
{
- const unsigned char *cs;
/*
* Be careful about RCU walk racing with rename:
- * use ACCESS_ONCE to fetch the name pointer.
+ * use 'lockless_dereference' to fetch the name pointer.
*
* NOTE! Even if a rename will mean that the length
* was not loaded atomically, we don't care. The
* early because the data cannot match (there can
* be no NUL in the ct/tcount data)
*/
- cs = ACCESS_ONCE(dentry->d_name.name);
- smp_read_barrier_depends();
+ const unsigned char *cs = lockless_dereference(dentry->d_name.name);
+
return dentry_string_cmp(cs, ct, tcount);
}
call_rcu(&dentry->d_u.d_rcu, __d_free);
}
-/**
- * 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_invalidate(struct dentry *dentry)
-{
- lockdep_assert_held(&dentry->d_lock);
- /* Go through am invalidation barrier */
- write_seqcount_invalidate(&dentry->d_seq);
-}
-
/*
* Release the dentry's inode, using the filesystem
- * d_iput() operation if defined. Dentry has no refcount
- * and is unhashed.
- */
-static void dentry_iput(struct dentry * dentry)
- __releases(dentry->d_lock)
- __releases(dentry->d_inode->i_lock)
-{
- struct inode *inode = dentry->d_inode;
- if (inode) {
- __d_clear_type_and_inode(dentry);
- hlist_del_init(&dentry->d_u.d_alias);
- spin_unlock(&dentry->d_lock);
- spin_unlock(&inode->i_lock);
- if (!inode->i_nlink)
- fsnotify_inoderemove(inode);
- if (dentry->d_op && dentry->d_op->d_iput)
- dentry->d_op->d_iput(dentry, inode);
- else
- iput(inode);
- } else {
- spin_unlock(&dentry->d_lock);
- }
-}
-
-/*
- * Release the dentry's inode, using the filesystem
- * d_iput() operation if defined. dentry remains in-use.
+ * d_iput() operation if defined.
*/
static void dentry_unlink_inode(struct dentry * dentry)
__releases(dentry->d_lock)
__releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
+ bool hashed = !d_unhashed(dentry);
- raw_write_seqcount_begin(&dentry->d_seq);
+ if (hashed)
+ raw_write_seqcount_begin(&dentry->d_seq);
__d_clear_type_and_inode(dentry);
hlist_del_init(&dentry->d_u.d_alias);
- raw_write_seqcount_end(&dentry->d_seq);
+ if (hashed)
+ raw_write_seqcount_end(&dentry->d_seq);
spin_unlock(&dentry->d_lock);
spin_unlock(&inode->i_lock);
if (!inode->i_nlink)
if (unlikely(IS_ROOT(dentry)))
b = &dentry->d_sb->s_anon;
else
- b = d_hash(dentry->d_parent, dentry->d_name.hash);
+ b = d_hash(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);
+ /* After this call, in-progress rcu-walk path lookup will fail. */
+ write_seqcount_invalidate(&dentry->d_seq);
}
}
EXPORT_SYMBOL(__d_drop);
dentry_unlist(dentry, parent);
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);
+ if (dentry->d_inode)
+ dentry_unlink_inode(dentry);
+ else
+ spin_unlock(&dentry->d_lock);
this_cpu_dec(nr_dentry);
if (dentry->d_op && dentry->d_op->d_release)
dentry->d_op->d_release(dentry);
failed:
spin_unlock(&dentry->d_lock);
- cpu_relax();
return dentry; /* try again with same dentry */
}
return;
repeat:
+ might_sleep();
+
rcu_read_lock();
if (likely(fast_dput(dentry))) {
rcu_read_unlock();
kill_it:
dentry = dentry_kill(dentry);
- if (dentry)
+ if (dentry) {
+ cond_resched();
goto repeat;
+ }
}
EXPORT_SYMBOL(dput);
{
struct dentry *dentry;
char *dname;
+ int err;
dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
if (!dentry)
INIT_LIST_HEAD(&dentry->d_child);
d_set_d_op(dentry, dentry->d_sb->s_d_op);
+ if (dentry->d_op && dentry->d_op->d_init) {
+ err = dentry->d_op->d_init(dentry);
+ if (err) {
+ if (dname_external(dentry))
+ kfree(external_name(dentry));
+ kmem_cache_free(dentry_cache, dentry);
+ return NULL;
+ }
+ }
+
this_cpu_inc(nr_dentry);
return dentry;
struct qstr q;
q.name = name;
- q.hash_len = hashlen_string(name);
+ q.hash_len = hashlen_string(parent, name);
return d_alloc(parent, &q);
}
EXPORT_SYMBOL(d_alloc_name);
DCACHE_OP_REVALIDATE |
DCACHE_OP_WEAK_REVALIDATE |
DCACHE_OP_DELETE |
- DCACHE_OP_SELECT_INODE |
DCACHE_OP_REAL));
dentry->d_op = op;
if (!op)
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;
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);
+ fsnotify_update_flags(dentry);
spin_unlock(&dentry->d_lock);
}
}
EXPORT_SYMBOL(d_add_ci);
-/*
- * Do the slow-case of the dentry name compare.
- *
- * Unlike the dentry_cmp() function, we need to atomically
- * 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.
- *
- * Thus the read_seqcount_retry() and the "duplicate" info
- * in arguments (the low-level filesystem should not look
- * at the dentry inode or name contents directly, since
- * rename can change them while we're in RCU mode).
- */
-enum slow_d_compare {
- D_COMP_OK,
- D_COMP_NOMATCH,
- D_COMP_SEQRETRY,
-};
-static noinline enum slow_d_compare slow_dentry_cmp(
- const struct dentry *parent,
- struct dentry *dentry,
- unsigned int seq,
- const struct qstr *name)
+static inline bool d_same_name(const struct dentry *dentry,
+ const struct dentry *parent,
+ const struct qstr *name)
{
- int tlen = dentry->d_name.len;
- const char *tname = dentry->d_name.name;
-
- if (read_seqcount_retry(&dentry->d_seq, seq)) {
- cpu_relax();
- return D_COMP_SEQRETRY;
+ if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) {
+ if (dentry->d_name.len != name->len)
+ return false;
+ return dentry_cmp(dentry, name->name, name->len) == 0;
}
- if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
- return D_COMP_NOMATCH;
- return D_COMP_OK;
+ return parent->d_op->d_compare(dentry,
+ dentry->d_name.len, dentry->d_name.name,
+ name) == 0;
}
/**
{
u64 hashlen = name->hash_len;
const unsigned char *str = name->name;
- struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen));
+ struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen));
struct hlist_bl_node *node;
struct dentry *dentry;
* dentry compare, we will do seqretries until it is stable,
* and if we end up with a successful lookup, we actually
* want to exit RCU lookup anyway.
+ *
+ * Note that raw_seqcount_begin still *does* smp_rmb(), so
+ * we are still guaranteed NUL-termination of ->d_name.name.
*/
seq = raw_seqcount_begin(&dentry->d_seq);
if (dentry->d_parent != parent)
continue;
if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
+ int tlen;
+ const char *tname;
if (dentry->d_name.hash != hashlen_hash(hashlen))
continue;
- *seqp = seq;
- switch (slow_dentry_cmp(parent, dentry, seq, name)) {
- case D_COMP_OK:
- return dentry;
- case D_COMP_NOMATCH:
- continue;
- default:
+ tlen = dentry->d_name.len;
+ tname = dentry->d_name.name;
+ /* we want a consistent (name,len) pair */
+ if (read_seqcount_retry(&dentry->d_seq, seq)) {
+ cpu_relax();
goto seqretry;
}
+ if (parent->d_op->d_compare(dentry,
+ tlen, tname, name) != 0)
+ continue;
+ } else {
+ if (dentry->d_name.hash_len != hashlen)
+ continue;
+ if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0)
+ continue;
}
-
- if (dentry->d_name.hash_len != hashlen)
- continue;
*seqp = seq;
- if (!dentry_cmp(dentry, str, hashlen_len(hashlen)))
- return dentry;
+ return dentry;
}
return NULL;
}
*/
struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
{
- unsigned int len = name->len;
unsigned int hash = name->hash;
- const unsigned char *str = name->name;
- struct hlist_bl_head *b = d_hash(parent, hash);
+ struct hlist_bl_head *b = d_hash(hash);
struct hlist_bl_node *node;
struct dentry *found = NULL;
struct dentry *dentry;
if (d_unhashed(dentry))
goto next;
- /*
- * It is safe to compare names since d_move() cannot
- * change the qstr (protected by d_lock).
- */
- 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 next;
- } else {
- if (dentry->d_name.len != len)
- goto next;
- if (dentry_cmp(dentry, str, len))
- goto next;
- }
+ if (!d_same_name(dentry, parent, name))
+ goto next;
dentry->d_lockref.count++;
found = dentry;
* calculate the standard hash first, as the d_op->d_hash()
* routine may choose to leave the hash value unchanged.
*/
- name->hash = full_name_hash(name->name, name->len);
+ name->hash = full_name_hash(dir, name->name, name->len);
if (dir->d_flags & DCACHE_OP_HASH) {
int err = dir->d_op->d_hash(dir, name);
if (unlikely(err < 0))
}
EXPORT_SYMBOL(d_delete);
-static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
+static void __d_rehash(struct dentry *entry)
{
+ struct hlist_bl_head *b = d_hash(entry->d_name.hash);
BUG_ON(!d_unhashed(entry));
hlist_bl_lock(b);
hlist_bl_add_head_rcu(&entry->d_hash, b);
hlist_bl_unlock(b);
}
-static void _d_rehash(struct dentry * entry)
-{
- __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
-}
-
/**
* d_rehash - add an entry back to the hash
* @entry: dentry to add to the hash
void d_rehash(struct dentry * entry)
{
spin_lock(&entry->d_lock);
- _d_rehash(entry);
+ __d_rehash(entry);
spin_unlock(&entry->d_lock);
}
EXPORT_SYMBOL(d_rehash);
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);
continue;
if (dentry->d_parent != parent)
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;
- }
+ if (!d_same_name(dentry, parent, name))
+ continue;
hlist_bl_unlock(b);
/* now we can try to grab a reference */
if (!lockref_get_not_dead(&dentry->d_lockref)) {
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;
- }
+ if (unlikely(!d_same_name(dentry, parent, name)))
+ goto mismatch;
/* OK, it *is* a hashed match; return it */
spin_unlock(&dentry->d_lock);
dput(new);
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);
+ fsnotify_update_flags(dentry);
}
- _d_rehash(dentry);
+ __d_rehash(dentry);
if (dir)
end_dir_add(dir, n);
spin_unlock(&dentry->d_lock);
struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode)
{
struct dentry *alias;
- int len = entry->d_name.len;
- const char *name = entry->d_name.name;
unsigned int hash = entry->d_name.hash;
spin_lock(&inode->i_lock);
continue;
if (alias->d_parent != entry->d_parent)
continue;
- if (alias->d_name.len != len)
- continue;
- if (dentry_cmp(alias, name, len))
+ if (!d_same_name(alias, entry->d_parent, &entry->d_name))
continue;
spin_lock(&alias->d_lock);
if (!d_unhashed(alias)) {
alias = NULL;
} else {
__dget_dlock(alias);
- _d_rehash(alias);
+ __d_rehash(alias);
spin_unlock(&alias->d_lock);
}
spin_unlock(&inode->i_lock);
* Parent inode i_mutex must be held over d_lookup and into this call (to
* keep renames and concurrent inserts, and readdir(2) away).
*/
-void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
+void dentry_update_name_case(struct dentry *dentry, const struct qstr *name)
{
BUG_ON(!inode_is_locked(dentry->d_parent->d_inode));
BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
write_seqcount_begin(&dentry->d_seq);
write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
+ /* unhash both */
/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
-
- /*
- * Move the dentry to the target hash queue. Don't bother checking
- * for the same hash queue because of how unlikely it is.
- */
__d_drop(dentry);
- __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
-
- /*
- * 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);
- if (exchange) {
- __d_rehash(target,
- d_hash(dentry->d_parent, dentry->d_name.hash));
- }
/* Switch the names.. */
if (exchange)
else
copy_name(dentry, target);
+ /* rehash in new place(s) */
+ __d_rehash(dentry);
+ if (exchange)
+ __d_rehash(target);
+
/* ... and switch them in the tree */
if (IS_ROOT(dentry)) {
/* splicing a tree */
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);
+ fsnotify_update_flags(target);
+ fsnotify_update_flags(dentry);
}
write_seqcount_end(&target->d_seq);
* 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)
+static int prepend_name(char **buffer, int *buflen, const struct qstr *name)
{
const char *dname = ACCESS_ONCE(name->name);
u32 dlen = ACCESS_ONCE(name->len);
projects / cascardo / linux.git / blobdiff