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. */
if (!tcount)
return 0;
}
- mask = ~(~0ul << tcount*8);
+ mask = bytemask_from_count(tcount);
return unlikely(!!((a ^ b) & mask));
}
__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);
}
}
}
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_u.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) &&
- !d_unhashed(dentry))
- dentry->d_op->d_prune(dentry);
-
- dentry_lru_del(dentry);
- __d_shrink(dentry);
-
- if (dentry->d_lockref.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_lockref.count,
- dentry->d_sb->s_type->name,
- dentry->d_sb->s_id);
- BUG();
- }
-
- if (IS_ROOT(dentry)) {
- parent = NULL;
- list_del(&dentry->d_u.d_child);
- } else {
- parent = dentry->d_parent;
- parent->d_lockref.count--;
- list_del(&dentry->d_u.d_child);
- }
-
- inode = dentry->d_inode;
- if (inode) {
- dentry->d_inode = NULL;
- hlist_del_init(&dentry->d_alias);
- if (dentry->d_op && dentry->d_op->d_iput)
- dentry->d_op->d_iput(dentry, inode);
- else
- iput(inode);
- }
-
- d_free(dentry);
-
- /* 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));
-
- dentry = list_entry(dentry->d_subdirs.next,
- struct dentry, d_u.d_child);
- }
-}
-
-/*
- * 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_lockref.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);
- }
-}
-
-/*
- * 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;
}
}
EXPORT_SYMBOL(shrink_dcache_parent);
+static enum d_walk_ret umount_collect(void *_data, struct dentry *dentry)
+{
+ struct select_data *data = _data;
+ enum d_walk_ret ret = D_WALK_CONTINUE;
+
+ if (dentry->d_lockref.count) {
+ dentry_lru_del(dentry);
+ if (likely(!list_empty(&dentry->d_subdirs)))
+ goto out;
+ if (dentry == data->start && dentry->d_lockref.count == 1)
+ goto out;
+ 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_lockref.count,
+ dentry->d_sb->s_type->name,
+ dentry->d_sb->s_id);
+ BUG();
+ } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
+ /*
+ * We can't use d_lru_shrink_move() because we
+ * need to get the global LRU lock and do the
+ * LRU accounting.
+ */
+ if (dentry->d_flags & DCACHE_LRU_LIST)
+ d_lru_del(dentry);
+ d_shrink_add(dentry, &data->dispose);
+ data->found++;
+ ret = D_WALK_NORETRY;
+ }
+out:
+ if (data->found && need_resched())
+ ret = D_WALK_QUIT;
+ return ret;
+}
+
+/*
+ * destroy the dentries attached to a superblock on unmounting
+ */
+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;
+ for (;;) {
+ struct select_data data;
+
+ INIT_LIST_HEAD(&data.dispose);
+ data.start = dentry;
+ data.found = 0;
+
+ d_walk(dentry, &data, umount_collect, NULL);
+ if (!data.found)
+ break;
+
+ shrink_dentry_list(&data.dispose);
+ cond_resched();
+ }
+ d_drop(dentry);
+ dput(dentry);
+
+ while (!hlist_bl_empty(&sb->s_anon)) {
+ struct select_data data;
+ dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
+
+ INIT_LIST_HEAD(&data.dispose);
+ data.start = NULL;
+ data.found = 0;
+
+ d_walk(dentry, &data, umount_collect, NULL);
+ if (data.found)
+ shrink_dentry_list(&data.dispose);
+ cond_resched();
+ }
+}
+
static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry)
{
struct select_data *data = _data;
}
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);
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_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;
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;
+ 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;
}
}
done_seqretry(&rename_lock, seq);
+ 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)
error = -ENAMETOOLONG;
int error;
prepend(&res, &buflen, "\0", 1);
- br_read_lock(&vfsmount_lock);
error = prepend_path(path, root, &res, &buflen);
- br_read_unlock(&vfsmount_lock);
if (error < 0)
return ERR_PTR(error);
int error;
prepend(&res, &buflen, "\0", 1);
- br_read_lock(&vfsmount_lock);
error = prepend_path(path, &root, &res, &buflen);
- br_read_unlock(&vfsmount_lock);
if (error > 1)
error = -EINVAL;
rcu_read_lock();
get_fs_root_rcu(current->fs, &root);
- br_read_lock(&vfsmount_lock);
error = path_with_deleted(path, &root, &res, &buflen);
- br_read_unlock(&vfsmount_lock);
rcu_read_unlock();
if (error < 0)
get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
error = -ENOENT;
- br_read_lock(&vfsmount_lock);
if (!d_unlinked(pwd.dentry)) {
unsigned long len;
char *cwd = page + PATH_MAX;
prepend(&cwd, &buflen, "\0", 1);
error = prepend_path(&pwd, &root, &cwd, &buflen);
- br_read_unlock(&vfsmount_lock);
rcu_read_unlock();
if (error < 0)
error = -EFAULT;
}
} else {
- br_read_unlock(&vfsmount_lock);
rcu_read_unlock();
}
projects / ~andy / linux / blobdiff