static struct kmem_cache *dentry_cache __read_mostly;
-/**
- * read_seqbegin_or_lock - begin a sequence number check or locking block
- * @lock: sequence lock
- * @seq : sequence number to be checked
- *
- * First try it once optimistically without taking the lock. If that fails,
- * take the lock. The sequence number is also used as a marker for deciding
- * whether to be a reader (even) or writer (odd).
- * N.B. seq must be initialized to an even number to begin with.
- */
-static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq)
-{
- if (!(*seq & 1)) /* Even */
- *seq = read_seqbegin(lock);
- else /* Odd */
- read_seqlock_excl(lock);
-}
-
-static inline int need_seqretry(seqlock_t *lock, int seq)
-{
- return !(seq & 1) && read_seqretry(lock, seq);
-}
-
-static inline void done_seqretry(seqlock_t *lock, int seq)
-{
- if (seq & 1)
- read_sequnlock_excl(lock);
-}
-
/*
* This is the single most critical data structure when it comes
* to the dcache: the hashtable for lookups. Somebody should try
* This hash-function tries to avoid losing too many bits of hash
* information, yet avoid using a prime hash-size or similar.
*/
-#define D_HASHBITS d_hash_shift
-#define D_HASHMASK d_hash_mask
static unsigned int d_hash_mask __read_mostly;
static unsigned int d_hash_shift __read_mostly;
unsigned int hash)
{
hash += (unsigned long) parent / L1_CACHE_BYTES;
- hash = hash + (hash >> D_HASHBITS);
- return dentry_hashtable + (hash & D_HASHMASK);
+ hash = hash + (hash >> d_hash_shift);
+ return dentry_hashtable + (hash & d_hash_mask);
}
/* Statistics gathering. */
__releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
+ __d_clear_type(dentry);
dentry->d_inode = NULL;
hlist_del_init(&dentry->d_alias);
dentry_rcuwalk_barrier(dentry);
{
list_del(&dentry->d_u.d_child);
/*
- * Inform try_to_ascend() that we are no longer attached to the
+ * Inform d_walk() that we are no longer attached to the
* dentry tree
*/
dentry->d_flags |= DCACHE_DENTRY_KILLED;
return parent;
}
-/*
- * 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.
- */
-static void __d_shrink(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);
- }
-}
-
/**
* d_drop - drop a dentry
* @dentry: dentry to drop
void __d_drop(struct dentry *dentry)
{
if (!d_unhashed(dentry)) {
- __d_shrink(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_barrier(dentry);
}
}
* 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 *
+static struct dentry *
dentry_kill(struct dentry *dentry, int unlock_on_failure)
__releases(dentry->d_lock)
{
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_lockref.count--;
}
EXPORT_SYMBOL(shrink_dcache_sb);
-/*
- * This tries to ascend one level of parenthood, but
- * we can race with renaming, so we need to re-check
- * the parenthood after dropping the lock and check
- * that the sequence number still matches.
- */
-static struct dentry *try_to_ascend(struct dentry *old, unsigned seq)
-{
- struct dentry *new = old->d_parent;
-
- rcu_read_lock();
- spin_unlock(&old->d_lock);
- spin_lock(&new->d_lock);
-
- /*
- * might go back up the wrong parent if we have had a rename
- * or deletion
- */
- if (new != old->d_parent ||
- (old->d_flags & DCACHE_DENTRY_KILLED) ||
- need_seqretry(&rename_lock, seq)) {
- spin_unlock(&new->d_lock);
- new = NULL;
- }
- rcu_read_unlock();
- return new;
-}
-
/**
* enum d_walk_ret - action to talke during tree walk
* @D_WALK_CONTINUE: contrinue walk
*/
if (this_parent != parent) {
struct dentry *child = this_parent;
- this_parent = try_to_ascend(this_parent, seq);
- if (!this_parent)
+ this_parent = child->d_parent;
+
+ rcu_read_lock();
+ spin_unlock(&child->d_lock);
+ spin_lock(&this_parent->d_lock);
+
+ /*
+ * might go back up the wrong parent if we have had a rename
+ * or deletion
+ */
+ if (this_parent != child->d_parent ||
+ (child->d_flags & DCACHE_DENTRY_KILLED) ||
+ need_seqretry(&rename_lock, seq)) {
+ spin_unlock(&this_parent->d_lock);
+ rcu_read_unlock();
goto rename_retry;
+ }
+ rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}
* list is non-empty and continue searching.
*/
-/**
- * have_submounts - check for mounts over a dentry
- * @parent: dentry to check.
- *
- * Return true if the parent or its subdirectories contain
- * a mount point
- */
-
static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
{
int *ret = data;
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;
}
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);
}
EXPORT_SYMBOL(d_set_d_op);
+static unsigned d_flags_for_inode(struct inode *inode)
+{
+ unsigned add_flags = DCACHE_FILE_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;
+ }
+ } else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
+ if (unlikely(inode->i_op->follow_link))
+ add_flags = DCACHE_SYMLINK_TYPE;
+ else
+ inode->i_opflags |= IOP_NOFOLLOW;
+ }
+
+ 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;
+ dentry->d_flags &= ~DCACHE_ENTRY_TYPE;
+ dentry->d_flags |= add_flags;
+ if (inode)
hlist_add_head(&dentry->d_alias, &inode->i_dentry);
- }
dentry->d_inode = inode;
dentry_rcuwalk_barrier(dentry);
spin_unlock(&dentry->d_lock);
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) | DCACHE_DISCONNECTED;
+
spin_lock(&tmp->d_lock);
tmp->d_inode = inode;
- tmp->d_flags |= DCACHE_DISCONNECTED;
+ tmp->d_flags |= add_flags;
hlist_add_head(&tmp->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);
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. */
dentry_lock_for_move(anon, dentry);
write_seqcount_begin(&dentry->d_seq);
- write_seqcount_begin(&anon->d_seq);
+ write_seqcount_begin_nested(&anon->d_seq, DENTRY_D_LOCK_NESTED);
dparent = dentry->d_parent;
spin_unlock(&dentry->d_lock);
/* anon->d_lock still locked, returns locked */
- anon->d_flags &= ~DCACHE_DISCONNECTED;
}
/**
const struct path *root,
char **buffer, int *buflen)
{
- struct dentry *dentry = path->dentry;
- struct vfsmount *vfsmnt = path->mnt;
- struct mount *mnt = real_mount(vfsmnt);
+ struct dentry *dentry;
+ struct vfsmount *vfsmnt;
+ struct mount *mnt;
int error = 0;
- unsigned seq = 0;
+ unsigned seq, m_seq = 0;
char *bptr;
int blen;
- br_read_lock(&vfsmount_lock);
+ 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);
/* Global root? */
- if (mnt_has_parent(mnt)) {
- dentry = mnt->mnt_mountpoint;
- mnt = mnt->mnt_parent;
+ if (mnt != parent) {
+ dentry = ACCESS_ONCE(mnt->mnt_mountpoint);
+ mnt = parent;
vfsmnt = &mnt->mnt;
continue;
}
goto restart;
}
done_seqretry(&rename_lock, seq);
- br_read_unlock(&vfsmount_lock);
+
+ 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);
if (error >= 0 && bptr == *buffer) {
if (--blen < 0)
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blobdiff