* the dcache entry is deleted or garbage collected.
*/
-#include <linux/syscalls.h>
+#include <linux/ratelimit.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/hash.h>
#include <linux/cache.h>
#include <linux/export.h>
-#include <linux/mount.h>
-#include <linux/file.h>
-#include <linux/uaccess.h>
#include <linux/security.h>
#include <linux/seqlock.h>
-#include <linux/swap.h>
#include <linux/bootmem.h>
-#include <linux/fs_struct.h>
#include <linux/bit_spinlock.h>
#include <linux/rculist_bl.h>
-#include <linux/prefetch.h>
-#include <linux/ratelimit.h>
#include <linux/list_lru.h>
#include "internal.h"
#include "mount.h"
* dentry->d_lock
*
* If no ancestor relationship:
- * if (dentry1 < dentry2)
- * dentry1->d_lock
- * dentry2->d_lock
+ * arbitrary, since it's serialized on rename_lock
*/
int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
list_lru_isolate_move(lru, &dentry->d_lru, list);
}
-/*
- * dentry_lru_(add|del)_list) must be called with d_lock held.
- */
-static void dentry_lru_add(struct dentry *dentry)
-{
- if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
- d_lru_add(dentry);
- else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
- dentry->d_flags |= DCACHE_REFERENCED;
-}
-
/**
* d_drop - drop a dentry
* @dentry: dentry to drop
*/
static void ___d_drop(struct dentry *dentry)
{
- if (!d_unhashed(dentry)) {
- struct hlist_bl_head *b;
- /*
- * Hashed dentries are normally on the dentry hashtable,
- * with the exception of those newly allocated by
- * d_obtain_root, which are always IS_ROOT:
- */
- if (unlikely(IS_ROOT(dentry)))
- b = &dentry->d_sb->s_roots;
- else
- b = d_hash(dentry->d_name.hash);
+ struct hlist_bl_head *b;
+ /*
+ * Hashed dentries are normally on the dentry hashtable,
+ * with the exception of those newly allocated by
+ * d_obtain_root, which are always IS_ROOT:
+ */
+ if (unlikely(IS_ROOT(dentry)))
+ b = &dentry->d_sb->s_roots;
+ else
+ b = d_hash(dentry->d_name.hash);
- hlist_bl_lock(b);
- __hlist_bl_del(&dentry->d_hash);
- hlist_bl_unlock(b);
- /* After this call, in-progress rcu-walk path lookup will fail. */
- write_seqcount_invalidate(&dentry->d_seq);
- }
+ hlist_bl_lock(b);
+ __hlist_bl_del(&dentry->d_hash);
+ hlist_bl_unlock(b);
}
void __d_drop(struct dentry *dentry)
{
- ___d_drop(dentry);
- dentry->d_hash.pprev = NULL;
+ if (!d_unhashed(dentry)) {
+ ___d_drop(dentry);
+ dentry->d_hash.pprev = NULL;
+ write_seqcount_invalidate(&dentry->d_seq);
+ }
}
EXPORT_SYMBOL(__d_drop);
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 struct dentry *dentry_kill(struct dentry *dentry)
- __releases(dentry->d_lock)
-{
- struct inode *inode = dentry->d_inode;
- struct dentry *parent = NULL;
-
- 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);
- return dentry; /* try again with same dentry */
-}
-
-static inline struct dentry *lock_parent(struct dentry *dentry)
+static struct dentry *__lock_parent(struct dentry *dentry)
{
- struct dentry *parent = dentry->d_parent;
- if (IS_ROOT(dentry))
- return NULL;
- if (unlikely(dentry->d_lockref.count < 0))
- return NULL;
- if (likely(spin_trylock(&parent->d_lock)))
- return parent;
+ struct dentry *parent;
rcu_read_lock();
spin_unlock(&dentry->d_lock);
again:
return parent;
}
+static inline struct dentry *lock_parent(struct dentry *dentry)
+{
+ struct dentry *parent = dentry->d_parent;
+ if (IS_ROOT(dentry))
+ return NULL;
+ if (likely(spin_trylock(&parent->d_lock)))
+ return parent;
+ return __lock_parent(dentry);
+}
+
+static inline bool retain_dentry(struct dentry *dentry)
+{
+ WARN_ON(d_in_lookup(dentry));
+
+ /* Unreachable? Get rid of it */
+ if (unlikely(d_unhashed(dentry)))
+ return false;
+
+ if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
+ return false;
+
+ if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
+ if (dentry->d_op->d_delete(dentry))
+ return false;
+ }
+ /* retain; LRU fodder */
+ dentry->d_lockref.count--;
+ if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
+ d_lru_add(dentry);
+ else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
+ dentry->d_flags |= DCACHE_REFERENCED;
+ return true;
+}
+
+/*
+ * Finish off a dentry we've decided to kill.
+ * dentry->d_lock must be held, returns with it unlocked.
+ * Returns dentry requiring refcount drop, or NULL if we're done.
+ */
+static struct dentry *dentry_kill(struct dentry *dentry)
+ __releases(dentry->d_lock)
+{
+ struct inode *inode = dentry->d_inode;
+ struct dentry *parent = NULL;
+
+ if (inode && unlikely(!spin_trylock(&inode->i_lock)))
+ goto slow_positive;
+
+ if (!IS_ROOT(dentry)) {
+ parent = dentry->d_parent;
+ if (unlikely(!spin_trylock(&parent->d_lock))) {
+ parent = __lock_parent(dentry);
+ if (likely(inode || !dentry->d_inode))
+ goto got_locks;
+ /* negative that became positive */
+ if (parent)
+ spin_unlock(&parent->d_lock);
+ inode = dentry->d_inode;
+ goto slow_positive;
+ }
+ }
+ __dentry_kill(dentry);
+ return parent;
+
+slow_positive:
+ spin_unlock(&dentry->d_lock);
+ spin_lock(&inode->i_lock);
+ spin_lock(&dentry->d_lock);
+ parent = lock_parent(dentry);
+got_locks:
+ if (unlikely(dentry->d_lockref.count != 1)) {
+ dentry->d_lockref.count--;
+ } else if (likely(!retain_dentry(dentry))) {
+ __dentry_kill(dentry);
+ return parent;
+ }
+ /* we are keeping it, after all */
+ if (inode)
+ spin_unlock(&inode->i_lock);
+ if (parent)
+ spin_unlock(&parent->d_lock);
+ spin_unlock(&dentry->d_lock);
+ return NULL;
+}
+
/*
* Try to do a lockless dput(), and return whether that was successful.
*
/* 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;
-
- if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
- goto kill_it;
-
- if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
- if (dentry->d_op->d_delete(dentry))
- goto kill_it;
+ if (likely(retain_dentry(dentry))) {
+ spin_unlock(&dentry->d_lock);
+ return;
}
- dentry_lru_add(dentry);
-
- dentry->d_lockref.count--;
- spin_unlock(&dentry->d_lock);
- return;
-
-kill_it:
dentry = dentry_kill(dentry);
if (dentry) {
cond_resched();
}
EXPORT_SYMBOL(d_prune_aliases);
-static void shrink_dentry_list(struct list_head *list)
+/*
+ * Lock a dentry from shrink list.
+ * Called under rcu_read_lock() and dentry->d_lock; the former
+ * guarantees that nothing we access will be freed under us.
+ * Note that dentry is *not* protected from concurrent dentry_kill(),
+ * d_delete(), etc.
+ *
+ * Return false if dentry has been disrupted or grabbed, leaving
+ * the caller to kick it off-list. Otherwise, return true and have
+ * that dentry's inode and parent both locked.
+ */
+static bool shrink_lock_dentry(struct dentry *dentry)
{
- struct dentry *dentry, *parent;
+ struct inode *inode;
+ struct dentry *parent;
- while (!list_empty(list)) {
- struct inode *inode;
- dentry = list_entry(list->prev, struct dentry, d_lru);
+ if (dentry->d_lockref.count)
+ return false;
+
+ inode = dentry->d_inode;
+ if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
+ spin_unlock(&dentry->d_lock);
+ spin_lock(&inode->i_lock);
spin_lock(&dentry->d_lock);
- parent = lock_parent(dentry);
+ if (unlikely(dentry->d_lockref.count))
+ goto out;
+ /* changed inode means that somebody had grabbed it */
+ if (unlikely(inode != dentry->d_inode))
+ goto out;
+ }
- /*
- * 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);
+ parent = dentry->d_parent;
+ if (IS_ROOT(dentry) || likely(spin_trylock(&parent->d_lock)))
+ return true;
- /*
- * 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);
- if (parent)
- spin_unlock(&parent->d_lock);
- continue;
- }
+ spin_unlock(&dentry->d_lock);
+ spin_lock(&parent->d_lock);
+ if (unlikely(parent != dentry->d_parent)) {
+ spin_unlock(&parent->d_lock);
+ spin_lock(&dentry->d_lock);
+ goto out;
+ }
+ spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+ if (likely(!dentry->d_lockref.count))
+ return true;
+ spin_unlock(&parent->d_lock);
+out:
+ if (inode)
+ spin_unlock(&inode->i_lock);
+ return false;
+}
+static void shrink_dentry_list(struct list_head *list)
+{
+ while (!list_empty(list)) {
+ struct dentry *dentry, *parent;
- if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
- bool can_free = dentry->d_flags & DCACHE_MAY_FREE;
+ dentry = list_entry(list->prev, struct dentry, d_lru);
+ spin_lock(&dentry->d_lock);
+ rcu_read_lock();
+ if (!shrink_lock_dentry(dentry)) {
+ bool can_free = false;
+ rcu_read_unlock();
+ d_shrink_del(dentry);
+ if (dentry->d_lockref.count < 0)
+ 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;
}
-
- 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();
+ d_shrink_del(dentry);
+ parent = dentry->d_parent;
__dentry_kill(dentry);
-
+ if (parent == dentry)
+ continue;
/*
* We need to prune ancestors too. This is necessary to prevent
* quadratic behavior of shrink_dcache_parent(), but is also
* 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;
- }
+ while (dentry && !lockref_put_or_lock(&dentry->d_lockref))
+ dentry = dentry_kill(dentry);
}
}
void d_delete(struct dentry * dentry)
{
- struct inode *inode;
- int isdir = 0;
+ struct inode *inode = dentry->d_inode;
+ int isdir = d_is_dir(dentry);
+
+ spin_lock(&inode->i_lock);
+ spin_lock(&dentry->d_lock);
/*
* Are we the only user?
*/
-again:
- spin_lock(&dentry->d_lock);
- inode = dentry->d_inode;
- isdir = S_ISDIR(inode->i_mode);
if (dentry->d_lockref.count == 1) {
- if (!spin_trylock(&inode->i_lock)) {
- spin_unlock(&dentry->d_lock);
- cpu_relax();
- goto again;
- }
dentry->d_flags &= ~DCACHE_CANT_MOUNT;
dentry_unlink_inode(dentry);
- fsnotify_nameremove(dentry, isdir);
- return;
- }
-
- if (!d_unhashed(dentry))
+ } else {
__d_drop(dentry);
-
- spin_unlock(&dentry->d_lock);
-
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&inode->i_lock);
+ }
fsnotify_nameremove(dentry, isdir);
}
EXPORT_SYMBOL(d_delete);
retry:
rcu_read_lock();
- seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1;
+ seq = smp_load_acquire(&parent->d_inode->i_dir_seq);
r_seq = read_seqbegin(&rename_lock);
dentry = __d_lookup_rcu(parent, name, &d_seq);
if (unlikely(dentry)) {
rcu_read_unlock();
goto retry;
}
+
+ if (unlikely(seq & 1)) {
+ rcu_read_unlock();
+ goto retry;
+ }
+
hlist_bl_lock(b);
- if (unlikely(parent->d_inode->i_dir_seq != seq)) {
+ if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) {
hlist_bl_unlock(b);
rcu_read_unlock();
goto retry;
kfree_rcu(old_name, u.head);
}
-static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
-{
- /*
- * XXXX: do we really need to take target->d_lock?
- */
- if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
- spin_lock(&target->d_parent->d_lock);
- else {
- if (d_ancestor(dentry->d_parent, target->d_parent)) {
- spin_lock(&dentry->d_parent->d_lock);
- spin_lock_nested(&target->d_parent->d_lock,
- DENTRY_D_LOCK_NESTED);
- } else {
- spin_lock(&target->d_parent->d_lock);
- spin_lock_nested(&dentry->d_parent->d_lock,
- DENTRY_D_LOCK_NESTED);
- }
- }
- if (target < dentry) {
- spin_lock_nested(&target->d_lock, 2);
- spin_lock_nested(&dentry->d_lock, 3);
- } else {
- spin_lock_nested(&dentry->d_lock, 2);
- spin_lock_nested(&target->d_lock, 3);
- }
-}
-
-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, 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
static void __d_move(struct dentry *dentry, struct dentry *target,
bool exchange)
{
+ struct dentry *old_parent, *p;
struct inode *dir = NULL;
unsigned n;
- if (!dentry->d_inode)
- printk(KERN_WARNING "VFS: moving negative dcache entry\n");
- BUG_ON(d_ancestor(dentry, target));
+ WARN_ON(!dentry->d_inode);
+ if (WARN_ON(dentry == target))
+ return;
+
BUG_ON(d_ancestor(target, dentry));
+ old_parent = dentry->d_parent;
+ p = d_ancestor(old_parent, target);
+ if (IS_ROOT(dentry)) {
+ BUG_ON(p);
+ spin_lock(&target->d_parent->d_lock);
+ } else if (!p) {
+ /* target is not a descendent of dentry->d_parent */
+ spin_lock(&target->d_parent->d_lock);
+ spin_lock_nested(&old_parent->d_lock, DENTRY_D_LOCK_NESTED);
+ } else {
+ BUG_ON(p == dentry);
+ spin_lock(&old_parent->d_lock);
+ if (p != target)
+ spin_lock_nested(&target->d_parent->d_lock,
+ DENTRY_D_LOCK_NESTED);
+ }
+ spin_lock_nested(&dentry->d_lock, 2);
+ spin_lock_nested(&target->d_lock, 3);
- dentry_lock_for_move(dentry, target);
if (unlikely(d_in_lookup(target))) {
dir = target->d_parent->d_inode;
n = start_dir_add(dir);
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. */
- ___d_drop(dentry);
- ___d_drop(target);
+ if (!d_unhashed(dentry))
+ ___d_drop(dentry);
+ if (!d_unhashed(target))
+ ___d_drop(target);
- /* Switch the names.. */
- if (exchange)
- swap_names(dentry, target);
- else
+ /* ... and switch them in the tree */
+ dentry->d_parent = target->d_parent;
+ if (!exchange) {
copy_name(dentry, target);
-
- /* rehash in new place(s) */
- __d_rehash(dentry);
- if (exchange)
- __d_rehash(target);
- else
target->d_hash.pprev = NULL;
-
- /* ... 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;
- list_del_init(&target->d_child);
- list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
+ dentry->d_parent->d_lockref.count++;
+ if (dentry == old_parent)
+ dentry->d_flags |= DCACHE_RCUACCESS;
+ else
+ WARN_ON(!--old_parent->d_lockref.count);
} else {
- /* swapping two dentries */
- swap(dentry->d_parent, target->d_parent);
+ target->d_parent = old_parent;
+ swap_names(dentry, target);
list_move(&target->d_child, &target->d_parent->d_subdirs);
- list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
- if (exchange)
- fsnotify_update_flags(target);
- fsnotify_update_flags(dentry);
+ __d_rehash(target);
+ fsnotify_update_flags(target);
}
+ list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
+ __d_rehash(dentry);
+ fsnotify_update_flags(dentry);
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);
+
+ if (dentry->d_parent != old_parent)
+ spin_unlock(&dentry->d_parent->d_lock);
+ if (dentry != old_parent)
+ spin_unlock(&old_parent->d_lock);
+ spin_unlock(&target->d_lock);
+ spin_unlock(&dentry->d_lock);
}
/*
inode->i_sb->s_type->name,
inode->i_sb->s_id);
} else if (!IS_ROOT(new)) {
+ struct dentry *old_parent = dget(new->d_parent);
int err = __d_unalias(inode, dentry, new);
write_sequnlock(&rename_lock);
if (err) {
dput(new);
new = ERR_PTR(err);
}
+ dput(old_parent);
} else {
__d_move(new, dentry, false);
write_sequnlock(&rename_lock);
}
EXPORT_SYMBOL(d_splice_alias);
-static int prepend(char **buffer, int *buflen, const char *str, int namelen)
-{
- *buflen -= namelen;
- if (*buflen < 0)
- return -ENAMETOOLONG;
- *buffer -= namelen;
- memcpy(*buffer, str, 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 READ_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.
- *
- * Load acquire is needed to make sure that we see that terminating NUL.
- */
-static int prepend_name(char **buffer, int *buflen, const struct qstr *name)
-{
- const char *dname = smp_load_acquire(&name->name); /* ^^^ */
- u32 dlen = READ_ONCE(name->len);
- char *p;
-
- *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;
-}
-
-/**
- * prepend_path - Prepend path string to a buffer
- * @path: the dentry/vfsmount to report
- * @root: root vfsmnt/dentry
- * @buffer: pointer to the end of the buffer
- * @buflen: pointer to buffer length
- *
- * 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;
- 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 = READ_ONCE(mnt->mnt_parent);
- /* Escaped? */
- if (dentry != vfsmnt->mnt_root) {
- bptr = *buffer;
- blen = *buflen;
- error = 3;
- break;
- }
- /* Global root? */
- if (mnt != parent) {
- dentry = READ_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);
- error = prepend_name(&bptr, &blen, &dentry->d_name);
- if (error)
- break;
-
- dentry = parent;
- }
- if (!(seq & 1))
- rcu_read_unlock();
- if (need_seqretry(&rename_lock, seq)) {
- seq = 1;
- goto restart;
- }
- 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;
- else
- *--bptr = '/';
- }
- *buffer = bptr;
- *buflen = blen;
- return error;
-}
-
-/**
- * __d_path - return the path of a dentry
- * @path: the dentry/vfsmount to report
- * @root: root vfsmnt/dentry
- * @buf: buffer to return value in
- * @buflen: buffer length
- *
- * Convert a dentry into an ASCII path name.
- *
- * Returns a pointer into the buffer or an error code if the
- * path was too long.
- *
- * "buflen" should be positive.
- *
- * If the path is not reachable from the supplied root, return %NULL.
- */
-char *__d_path(const struct path *path,
- const struct path *root,
- char *buf, int buflen)
-{
- char *res = buf + buflen;
- int error;
-
- prepend(&res, &buflen, "\0", 1);
- error = prepend_path(path, root, &res, &buflen);
-
- if (error < 0)
- return ERR_PTR(error);
- if (error > 0)
- return NULL;
- return res;
-}
-
-char *d_absolute_path(const struct path *path,
- char *buf, int buflen)
-{
- struct path root = {};
- char *res = buf + buflen;
- int error;
-
- prepend(&res, &buflen, "\0", 1);
- error = prepend_path(path, &root, &res, &buflen);
-
- if (error > 1)
- error = -EINVAL;
- if (error < 0)
- return ERR_PTR(error);
- return res;
-}
-
-/*
- * same as __d_path but appends "(deleted)" for unlinked files.
- */
-static int path_with_deleted(const struct path *path,
- const struct path *root,
- char **buf, int *buflen)
-{
- prepend(buf, buflen, "\0", 1);
- if (d_unlinked(path->dentry)) {
- int error = prepend(buf, buflen, " (deleted)", 10);
- if (error)
- return error;
- }
-
- return prepend_path(path, root, buf, buflen);
-}
-
-static int prepend_unreachable(char **buffer, int *buflen)
-{
- 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
- * @buf: buffer to return value in
- * @buflen: buffer length
- *
- * Convert a dentry into an ASCII path name. If the entry has been deleted
- * the string " (deleted)" is appended. Note that this is ambiguous.
- *
- * Returns a pointer into the buffer or an error code if the path was
- * too long. Note: Callers should use the returned pointer, not the passed
- * in buffer, to use the name! The implementation often starts at an offset
- * into the buffer, and may leave 0 bytes at the start.
- *
- * "buflen" should be positive.
- */
-char *d_path(const struct path *path, char *buf, int buflen)
-{
- char *res = buf + buflen;
- struct path root;
- int error;
-
- /*
- * We have various synthetic filesystems that never get mounted. On
- * these filesystems dentries are never used for lookup purposes, and
- * thus don't need to be hashed. They also don't need a name until a
- * user wants to identify the object in /proc/pid/fd/. The little hack
- * below allows us to generate a name for these objects on demand:
- *
- * Some pseudo inodes are mountable. When they are mounted
- * path->dentry == path->mnt->mnt_root. In that case don't call d_dname
- * and instead have d_path return the mounted path.
- */
- if (path->dentry->d_op && path->dentry->d_op->d_dname &&
- (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root))
- return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
-
- rcu_read_lock();
- get_fs_root_rcu(current->fs, &root);
- error = path_with_deleted(path, &root, &res, &buflen);
- rcu_read_unlock();
-
- if (error < 0)
- res = ERR_PTR(error);
- return res;
-}
-EXPORT_SYMBOL(d_path);
-
-/*
- * Helper function for dentry_operations.d_dname() members
- */
-char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
- const char *fmt, ...)
-{
- va_list args;
- char temp[64];
- int sz;
-
- va_start(args, fmt);
- sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
- va_end(args);
-
- if (sz > sizeof(temp) || sz > buflen)
- return ERR_PTR(-ENAMETOOLONG);
-
- buffer += buflen - sz;
- return memcpy(buffer, temp, sz);
-}
-
-char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
-{
- char *end = buffer + buflen;
- /* these dentries are never renamed, so d_lock is not needed */
- if (prepend(&end, &buflen, " (deleted)", 11) ||
- 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 *d, char *buf, int buflen)
-{
- struct dentry *dentry;
- char *end, *retval;
- int len, seq = 0;
- int error = 0;
-
- 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;
-
- prefetch(parent);
- 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)
-{
- return __dentry_path(dentry, buf, buflen);
-}
-EXPORT_SYMBOL(dentry_path_raw);
-
-char *dentry_path(struct dentry *dentry, char *buf, int buflen)
-{
- char *p = NULL;
- char *retval;
-
- if (d_unlinked(dentry)) {
- p = buf + buflen;
- if (prepend(&p, &buflen, "//deleted", 10) != 0)
- goto Elong;
- buflen++;
- }
- retval = __dentry_path(dentry, buf, buflen);
- if (!IS_ERR(retval) && p)
- *p = '/'; /* restore '/' overriden with '\0' */
- return retval;
-Elong:
- 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
- * returns the length of the buffer filled (which
- * includes the ending '\0' character), or a negative
- * error value. So libc would do something like
- *
- * char *getcwd(char * buf, size_t size)
- * {
- * int retval;
- *
- * retval = sys_getcwd(buf, size);
- * if (retval >= 0)
- * return buf;
- * errno = -retval;
- * return NULL;
- * }
- */
-SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
-{
- int error;
- struct path pwd, root;
- char *page = __getname();
-
- if (!page)
- return -ENOMEM;
-
- rcu_read_lock();
- get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
-
- error = -ENOENT;
- if (!d_unlinked(pwd.dentry)) {
- unsigned long len;
- char *cwd = page + PATH_MAX;
- int buflen = PATH_MAX;
-
- prepend(&cwd, &buflen, "\0", 1);
- error = prepend_path(&pwd, &root, &cwd, &buflen);
- rcu_read_unlock();
-
- if (error < 0)
- goto out;
-
- /* Unreachable from current root */
- if (error > 0) {
- error = prepend_unreachable(&cwd, &buflen);
- if (error)
- goto out;
- }
-
- error = -ERANGE;
- len = PATH_MAX + page - cwd;
- if (len <= size) {
- error = len;
- if (copy_to_user(buf, cwd, len))
- error = -EFAULT;
- }
- } else {
- rcu_read_unlock();
- }
-
-out:
- __putname(page);
- return error;
-}
-
/*
* Test whether new_dentry is a subdirectory of old_dentry.
*
d_walk(parent, parent, d_genocide_kill, NULL);
}
+EXPORT_SYMBOL(d_genocide);
+
void d_tmpfile(struct dentry *dentry, struct inode *inode)
{
inode_dec_link_count(inode);
struct kmem_cache *names_cachep __read_mostly;
EXPORT_SYMBOL(names_cachep);
-EXPORT_SYMBOL(d_genocide);
-
void __init vfs_caches_init_early(void)
{
int i;
git.samba.org / sfrench / cifs-2.6.git / blobdiff