| /* |
| * fs/dcache.c |
| * |
| * Complete reimplementation |
| * (C) 1997 Thomas Schoebel-Theuer, |
| * with heavy changes by Linus Torvalds |
| */ |
| |
| /* |
| * Notes on the allocation strategy: |
| * |
| * The dcache is a master of the icache - whenever a dcache entry |
| * exists, the inode will always exist. "iput()" is done either when |
| * the dcache entry is deleted or garbage collected. |
| */ |
| |
| #include <linux/config.h> |
| #include <linux/syscalls.h> |
| #include <linux/string.h> |
| #include <linux/mm.h> |
| #include <linux/fs.h> |
| #include <linux/fsnotify.h> |
| #include <linux/slab.h> |
| #include <linux/init.h> |
| #include <linux/smp_lock.h> |
| #include <linux/hash.h> |
| #include <linux/cache.h> |
| #include <linux/module.h> |
| #include <linux/mount.h> |
| #include <linux/file.h> |
| #include <asm/uaccess.h> |
| #include <linux/security.h> |
| #include <linux/seqlock.h> |
| #include <linux/swap.h> |
| #include <linux/bootmem.h> |
| |
| /* #define DCACHE_DEBUG 1 */ |
| |
| int sysctl_vfs_cache_pressure = 100; |
| EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
| |
| __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); |
| static seqlock_t rename_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED; |
| |
| EXPORT_SYMBOL(dcache_lock); |
| |
| static kmem_cache_t *dentry_cache; |
| |
| #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) |
| |
| /* |
| * This is the single most critical data structure when it comes |
| * to the dcache: the hashtable for lookups. Somebody should try |
| * to make this good - I've just made it work. |
| * |
| * 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; |
| static unsigned int d_hash_shift; |
| static struct hlist_head *dentry_hashtable; |
| static LIST_HEAD(dentry_unused); |
| |
| /* Statistics gathering. */ |
| struct dentry_stat_t dentry_stat = { |
| .age_limit = 45, |
| }; |
| |
| static void d_callback(struct rcu_head *head) |
| { |
| struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); |
| |
| if (dname_external(dentry)) |
| kfree(dentry->d_name.name); |
| kmem_cache_free(dentry_cache, dentry); |
| } |
| |
| /* |
| * no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry |
| * inside dcache_lock. |
| */ |
| static void d_free(struct dentry *dentry) |
| { |
| if (dentry->d_op && dentry->d_op->d_release) |
| dentry->d_op->d_release(dentry); |
| call_rcu(&dentry->d_u.d_rcu, d_callback); |
| } |
| |
| /* |
| * Release the dentry's inode, using the filesystem |
| * d_iput() operation if defined. |
| * Called with dcache_lock and per dentry lock held, drops both. |
| */ |
| static void dentry_iput(struct dentry * dentry) |
| { |
| struct inode *inode = dentry->d_inode; |
| if (inode) { |
| dentry->d_inode = NULL; |
| list_del_init(&dentry->d_alias); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_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); |
| spin_unlock(&dcache_lock); |
| } |
| } |
| |
| /* |
| * This is dput |
| * |
| * This is complicated by the fact that we do not want to put |
| * dentries that are no longer on any hash chain on the unused |
| * list: we'd much rather just get rid of them immediately. |
| * |
| * However, that implies that we have to traverse the dentry |
| * tree upwards to the parents which might _also_ now be |
| * scheduled for deletion (it may have been only waiting for |
| * its last child to go away). |
| * |
| * This tail recursion is done by hand as we don't want to depend |
| * on the compiler to always get this right (gcc generally doesn't). |
| * Real recursion would eat up our stack space. |
| */ |
| |
| /* |
| * dput - release a dentry |
| * @dentry: dentry to release |
| * |
| * Release a dentry. This will drop the usage count and if appropriate |
| * call the dentry unlink method as well as removing it from the queues and |
| * releasing its resources. If the parent dentries were scheduled for release |
| * they too may now get deleted. |
| * |
| * no dcache lock, please. |
| */ |
| |
| void dput(struct dentry *dentry) |
| { |
| if (!dentry) |
| return; |
| |
| repeat: |
| if (atomic_read(&dentry->d_count) == 1) |
| might_sleep(); |
| if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) |
| return; |
| |
| spin_lock(&dentry->d_lock); |
| if (atomic_read(&dentry->d_count)) { |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_lock); |
| return; |
| } |
| |
| /* |
| * AV: ->d_delete() is _NOT_ allowed to block now. |
| */ |
| if (dentry->d_op && dentry->d_op->d_delete) { |
| if (dentry->d_op->d_delete(dentry)) |
| goto unhash_it; |
| } |
| /* Unreachable? Get rid of it */ |
| if (d_unhashed(dentry)) |
| goto kill_it; |
| if (list_empty(&dentry->d_lru)) { |
| dentry->d_flags |= DCACHE_REFERENCED; |
| list_add(&dentry->d_lru, &dentry_unused); |
| dentry_stat.nr_unused++; |
| } |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_lock); |
| return; |
| |
| unhash_it: |
| __d_drop(dentry); |
| |
| kill_it: { |
| struct dentry *parent; |
| |
| /* If dentry was on d_lru list |
| * delete it from there |
| */ |
| if (!list_empty(&dentry->d_lru)) { |
| list_del(&dentry->d_lru); |
| dentry_stat.nr_unused--; |
| } |
| list_del(&dentry->d_u.d_child); |
| dentry_stat.nr_dentry--; /* For d_free, below */ |
| /*drops the locks, at that point nobody can reach this dentry */ |
| dentry_iput(dentry); |
| parent = dentry->d_parent; |
| d_free(dentry); |
| if (dentry == parent) |
| return; |
| dentry = parent; |
| goto repeat; |
| } |
| } |
| |
| /** |
| * d_invalidate - invalidate a dentry |
| * @dentry: dentry to invalidate |
| * |
| * Try to invalidate the dentry if it turns out to be |
| * possible. If there are other dentries that can be |
| * reached through this one we can't delete it and we |
| * return -EBUSY. On success we return 0. |
| * |
| * no dcache lock. |
| */ |
| |
| int d_invalidate(struct dentry * dentry) |
| { |
| /* |
| * If it's already been dropped, return OK. |
| */ |
| spin_lock(&dcache_lock); |
| if (d_unhashed(dentry)) { |
| spin_unlock(&dcache_lock); |
| return 0; |
| } |
| /* |
| * Check whether to do a partial shrink_dcache |
| * to get rid of unused child entries. |
| */ |
| if (!list_empty(&dentry->d_subdirs)) { |
| spin_unlock(&dcache_lock); |
| shrink_dcache_parent(dentry); |
| spin_lock(&dcache_lock); |
| } |
| |
| /* |
| * Somebody else still using it? |
| * |
| * If it's a directory, we can't drop it |
| * for fear of somebody re-populating it |
| * with children (even though dropping it |
| * would make it unreachable from the root, |
| * we might still populate it if it was a |
| * working directory or similar). |
| */ |
| spin_lock(&dentry->d_lock); |
| if (atomic_read(&dentry->d_count) > 1) { |
| if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_lock); |
| return -EBUSY; |
| } |
| } |
| |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_lock); |
| return 0; |
| } |
| |
| /* This should be called _only_ with dcache_lock held */ |
| |
| static inline struct dentry * __dget_locked(struct dentry *dentry) |
| { |
| atomic_inc(&dentry->d_count); |
| if (!list_empty(&dentry->d_lru)) { |
| dentry_stat.nr_unused--; |
| list_del_init(&dentry->d_lru); |
| } |
| return dentry; |
| } |
| |
| struct dentry * dget_locked(struct dentry *dentry) |
| { |
| return __dget_locked(dentry); |
| } |
| |
| /** |
| * d_find_alias - grab a hashed alias of inode |
| * @inode: inode in question |
| * @want_discon: flag, used by d_splice_alias, to request |
| * that only a DISCONNECTED alias be returned. |
| * |
| * If inode has a hashed alias, or is a directory and has any alias, |
| * acquire the reference to alias and return it. Otherwise return NULL. |
| * Notice that if inode is a directory there can be only one alias and |
| * it can be unhashed only if it has no children, or if it is the root |
| * of a filesystem. |
| * |
| * If the inode has a DCACHE_DISCONNECTED alias, then prefer |
| * any other hashed alias over that one unless @want_discon is set, |
| * in which case only return a DCACHE_DISCONNECTED alias. |
| */ |
| |
| static struct dentry * __d_find_alias(struct inode *inode, int want_discon) |
| { |
| struct list_head *head, *next, *tmp; |
| struct dentry *alias, *discon_alias=NULL; |
| |
| head = &inode->i_dentry; |
| next = inode->i_dentry.next; |
| while (next != head) { |
| tmp = next; |
| next = tmp->next; |
| prefetch(next); |
| alias = list_entry(tmp, struct dentry, d_alias); |
| if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
| if (alias->d_flags & DCACHE_DISCONNECTED) |
| discon_alias = alias; |
| else if (!want_discon) { |
| __dget_locked(alias); |
| return alias; |
| } |
| } |
| } |
| if (discon_alias) |
| __dget_locked(discon_alias); |
| return discon_alias; |
| } |
| |
| struct dentry * d_find_alias(struct inode *inode) |
| { |
| struct dentry *de = NULL; |
| |
| if (!list_empty(&inode->i_dentry)) { |
| spin_lock(&dcache_lock); |
| de = __d_find_alias(inode, 0); |
| spin_unlock(&dcache_lock); |
| } |
| return de; |
| } |
| |
| /* |
| * Try to kill dentries associated with this inode. |
| * WARNING: you must own a reference to inode. |
| */ |
| void d_prune_aliases(struct inode *inode) |
| { |
| struct dentry *dentry; |
| restart: |
| spin_lock(&dcache_lock); |
| list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
| spin_lock(&dentry->d_lock); |
| if (!atomic_read(&dentry->d_count)) { |
| __dget_locked(dentry); |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_lock); |
| dput(dentry); |
| goto restart; |
| } |
| spin_unlock(&dentry->d_lock); |
| } |
| spin_unlock(&dcache_lock); |
| } |
| |
| /* |
| * Throw away a dentry - free the inode, dput the parent. |
| * This requires that the LRU list has already been |
| * removed. |
| * Called with dcache_lock, drops it and then regains. |
| */ |
| static inline void prune_one_dentry(struct dentry * dentry) |
| { |
| struct dentry * parent; |
| |
| __d_drop(dentry); |
| list_del(&dentry->d_u.d_child); |
| dentry_stat.nr_dentry--; /* For d_free, below */ |
| dentry_iput(dentry); |
| parent = dentry->d_parent; |
| d_free(dentry); |
| if (parent != dentry) |
| dput(parent); |
| spin_lock(&dcache_lock); |
| } |
| |
| /** |
| * prune_dcache - shrink the dcache |
| * @count: number of entries to try and free |
| * |
| * Shrink the dcache. This is done when we need |
| * more memory, or simply when we need to unmount |
| * something (at which point we need to unuse |
| * all dentries). |
| * |
| * This function may fail to free any resources if |
| * all the dentries are in use. |
| */ |
| |
| static void prune_dcache(int count) |
| { |
| spin_lock(&dcache_lock); |
| for (; count ; count--) { |
| struct dentry *dentry; |
| struct list_head *tmp; |
| |
| cond_resched_lock(&dcache_lock); |
| |
| tmp = dentry_unused.prev; |
| if (tmp == &dentry_unused) |
| break; |
| list_del_init(tmp); |
| prefetch(dentry_unused.prev); |
| dentry_stat.nr_unused--; |
| dentry = list_entry(tmp, struct dentry, d_lru); |
| |
| spin_lock(&dentry->d_lock); |
| /* |
| * We found an inuse dentry which was not removed from |
| * dentry_unused because of laziness during lookup. Do not free |
| * it - just keep it off the dentry_unused list. |
| */ |
| if (atomic_read(&dentry->d_count)) { |
| spin_unlock(&dentry->d_lock); |
| continue; |
| } |
| /* If the dentry was recently referenced, don't free it. */ |
| if (dentry->d_flags & DCACHE_REFERENCED) { |
| dentry->d_flags &= ~DCACHE_REFERENCED; |
| list_add(&dentry->d_lru, &dentry_unused); |
| dentry_stat.nr_unused++; |
| spin_unlock(&dentry->d_lock); |
| continue; |
| } |
| prune_one_dentry(dentry); |
| } |
| spin_unlock(&dcache_lock); |
| } |
| |
| /* |
| * Shrink the dcache for the specified super block. |
| * This allows us to unmount a device without disturbing |
| * the dcache for the other devices. |
| * |
| * This implementation makes just two traversals of the |
| * unused list. On the first pass we move the selected |
| * dentries to the most recent end, and on the second |
| * pass we free them. The second pass must restart after |
| * each dput(), but since the target dentries are all at |
| * the end, it's really just a single traversal. |
| */ |
| |
| /** |
| * shrink_dcache_sb - shrink dcache for a superblock |
| * @sb: superblock |
| * |
| * Shrink the dcache for the specified super block. This |
| * is used to free the dcache before unmounting a file |
| * system |
| */ |
| |
| void shrink_dcache_sb(struct super_block * sb) |
| { |
| struct list_head *tmp, *next; |
| struct dentry *dentry; |
| |
| /* |
| * Pass one ... move the dentries for the specified |
| * superblock to the most recent end of the unused list. |
| */ |
| spin_lock(&dcache_lock); |
| list_for_each_safe(tmp, next, &dentry_unused) { |
| dentry = list_entry(tmp, struct dentry, d_lru); |
| if (dentry->d_sb != sb) |
| continue; |
| list_del(tmp); |
| list_add(tmp, &dentry_unused); |
| } |
| |
| /* |
| * Pass two ... free the dentries for this superblock. |
| */ |
| repeat: |
| list_for_each_safe(tmp, next, &dentry_unused) { |
| dentry = list_entry(tmp, struct dentry, d_lru); |
| if (dentry->d_sb != sb) |
| continue; |
| dentry_stat.nr_unused--; |
| list_del_init(tmp); |
| spin_lock(&dentry->d_lock); |
| if (atomic_read(&dentry->d_count)) { |
| spin_unlock(&dentry->d_lock); |
| continue; |
| } |
| prune_one_dentry(dentry); |
| cond_resched_lock(&dcache_lock); |
| goto repeat; |
| } |
| spin_unlock(&dcache_lock); |
| } |
| |
| /* |
| * Search for at least 1 mount point in the dentry's subdirs. |
| * We descend to the next level whenever the d_subdirs |
| * 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 |
| */ |
| |
| int have_submounts(struct dentry *parent) |
| { |
| struct dentry *this_parent = parent; |
| struct list_head *next; |
| |
| spin_lock(&dcache_lock); |
| if (d_mountpoint(parent)) |
| goto positive; |
| repeat: |
| next = this_parent->d_subdirs.next; |
| resume: |
| while (next != &this_parent->d_subdirs) { |
| struct list_head *tmp = next; |
| struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
| next = tmp->next; |
| /* Have we found a mount point ? */ |
| if (d_mountpoint(dentry)) |
| goto positive; |
| if (!list_empty(&dentry->d_subdirs)) { |
| this_parent = dentry; |
| goto repeat; |
| } |
| } |
| /* |
| * All done at this level ... ascend and resume the search. |
| */ |
| if (this_parent != parent) { |
| next = this_parent->d_u.d_child.next; |
| this_parent = this_parent->d_parent; |
| goto resume; |
| } |
| spin_unlock(&dcache_lock); |
| return 0; /* No mount points found in tree */ |
| positive: |
| spin_unlock(&dcache_lock); |
| return 1; |
| } |
| |
| /* |
| * Search the dentry child list for the specified parent, |
| * and move any unused dentries to the end of the unused |
| * list for prune_dcache(). We descend to the next level |
| * whenever the d_subdirs list is non-empty and continue |
| * searching. |
| * |
| * It returns zero iff there are no unused children, |
| * otherwise it returns the number of children moved to |
| * the end of the unused list. This may not be the total |
| * number of unused children, because select_parent can |
| * drop the lock and return early due to latency |
| * constraints. |
| */ |
| static int select_parent(struct dentry * parent) |
| { |
| struct dentry *this_parent = parent; |
| struct list_head *next; |
| int found = 0; |
| |
| spin_lock(&dcache_lock); |
| repeat: |
| next = this_parent->d_subdirs.next; |
| resume: |
| while (next != &this_parent->d_subdirs) { |
| struct list_head *tmp = next; |
| struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
| next = tmp->next; |
| |
| if (!list_empty(&dentry->d_lru)) { |
| dentry_stat.nr_unused--; |
| list_del_init(&dentry->d_lru); |
| } |
| /* |
| * move only zero ref count dentries to the end |
| * of the unused list for prune_dcache |
| */ |
| if (!atomic_read(&dentry->d_count)) { |
| list_add(&dentry->d_lru, dentry_unused.prev); |
| dentry_stat.nr_unused++; |
| found++; |
| } |
| |
| /* |
| * We can return to the caller if we have found some (this |
| * ensures forward progress). We'll be coming back to find |
| * the rest. |
| */ |
| if (found && need_resched()) |
| goto out; |
| |
| /* |
| * Descend a level if the d_subdirs list is non-empty. |
| */ |
| if (!list_empty(&dentry->d_subdirs)) { |
| this_parent = dentry; |
| #ifdef DCACHE_DEBUG |
| printk(KERN_DEBUG "select_parent: descending to %s/%s, found=%d\n", |
| dentry->d_parent->d_name.name, dentry->d_name.name, found); |
| #endif |
| goto repeat; |
| } |
| } |
| /* |
| * All done at this level ... ascend and resume the search. |
| */ |
| if (this_parent != parent) { |
| next = this_parent->d_u.d_child.next; |
| this_parent = this_parent->d_parent; |
| #ifdef DCACHE_DEBUG |
| printk(KERN_DEBUG "select_parent: ascending to %s/%s, found=%d\n", |
| this_parent->d_parent->d_name.name, this_parent->d_name.name, found); |
| #endif |
| goto resume; |
| } |
| out: |
| spin_unlock(&dcache_lock); |
| return found; |
| } |
| |
| /** |
| * shrink_dcache_parent - prune dcache |
| * @parent: parent of entries to prune |
| * |
| * Prune the dcache to remove unused children of the parent dentry. |
| */ |
| |
| void shrink_dcache_parent(struct dentry * parent) |
| { |
| int found; |
| |
| while ((found = select_parent(parent)) != 0) |
| prune_dcache(found); |
| } |
| |
| /** |
| * shrink_dcache_anon - further prune the cache |
| * @head: head of d_hash list of dentries to prune |
| * |
| * Prune the dentries that are anonymous |
| * |
| * parsing d_hash list does not hlist_for_each_entry_rcu() as it |
| * done under dcache_lock. |
| * |
| */ |
| void shrink_dcache_anon(struct hlist_head *head) |
| { |
| struct hlist_node *lp; |
| int found; |
| do { |
| found = 0; |
| spin_lock(&dcache_lock); |
| hlist_for_each(lp, head) { |
| struct dentry *this = hlist_entry(lp, struct dentry, d_hash); |
| if (!list_empty(&this->d_lru)) { |
| dentry_stat.nr_unused--; |
| list_del_init(&this->d_lru); |
| } |
| |
| /* |
| * move only zero ref count dentries to the end |
| * of the unused list for prune_dcache |
| */ |
| if (!atomic_read(&this->d_count)) { |
| list_add_tail(&this->d_lru, &dentry_unused); |
| dentry_stat.nr_unused++; |
| found++; |
| } |
| } |
| spin_unlock(&dcache_lock); |
| prune_dcache(found); |
| } while(found); |
| } |
| |
| /* |
| * Scan `nr' dentries and return the number which remain. |
| * |
| * We need to avoid reentering the filesystem if the caller is performing a |
| * GFP_NOFS allocation attempt. One example deadlock is: |
| * |
| * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> |
| * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> |
| * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. |
| * |
| * In this case we return -1 to tell the caller that we baled. |
| */ |
| static int shrink_dcache_memory(int nr, gfp_t gfp_mask) |
| { |
| if (nr) { |
| if (!(gfp_mask & __GFP_FS)) |
| return -1; |
| prune_dcache(nr); |
| } |
| return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; |
| } |
| |
| /** |
| * d_alloc - allocate a dcache entry |
| * @parent: parent of entry to allocate |
| * @name: qstr of the name |
| * |
| * Allocates a dentry. It returns %NULL if there is insufficient memory |
| * available. On a success the dentry is returned. The name passed in is |
| * copied and the copy passed in may be reused after this call. |
| */ |
| |
| struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
| { |
| struct dentry *dentry; |
| char *dname; |
| |
| dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
| if (!dentry) |
| return NULL; |
| |
| if (name->len > DNAME_INLINE_LEN-1) { |
| dname = kmalloc(name->len + 1, GFP_KERNEL); |
| if (!dname) { |
| kmem_cache_free(dentry_cache, dentry); |
| return NULL; |
| } |
| } else { |
| dname = dentry->d_iname; |
| } |
| dentry->d_name.name = dname; |
| |
| dentry->d_name.len = name->len; |
| dentry->d_name.hash = name->hash; |
| memcpy(dname, name->name, name->len); |
| dname[name->len] = 0; |
| |
| atomic_set(&dentry->d_count, 1); |
| dentry->d_flags = DCACHE_UNHASHED; |
| spin_lock_init(&dentry->d_lock); |
| dentry->d_inode = NULL; |
| dentry->d_parent = NULL; |
| dentry->d_sb = NULL; |
| dentry->d_op = NULL; |
| dentry->d_fsdata = NULL; |
| dentry->d_mounted = 0; |
| #ifdef CONFIG_PROFILING |
| dentry->d_cookie = NULL; |
| #endif |
| INIT_HLIST_NODE(&dentry->d_hash); |
| INIT_LIST_HEAD(&dentry->d_lru); |
| INIT_LIST_HEAD(&dentry->d_subdirs); |
| INIT_LIST_HEAD(&dentry->d_alias); |
| |
| if (parent) { |
| dentry->d_parent = dget(parent); |
| dentry->d_sb = parent->d_sb; |
| } else { |
| INIT_LIST_HEAD(&dentry->d_u.d_child); |
| } |
| |
| spin_lock(&dcache_lock); |
| if (parent) |
| list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
| dentry_stat.nr_dentry++; |
| spin_unlock(&dcache_lock); |
| |
| return dentry; |
| } |
| |
| 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); |
| return d_alloc(parent, &q); |
| } |
| |
| /** |
| * d_instantiate - fill in inode information for a dentry |
| * @entry: dentry to complete |
| * @inode: inode to attach to this dentry |
| * |
| * Fill in inode information in the entry. |
| * |
| * This turns negative dentries into productive full members |
| * of society. |
| * |
| * NOTE! This assumes that the inode count has been incremented |
| * (or otherwise set) by the caller to indicate that it is now |
| * in use by the dcache. |
| */ |
| |
| void d_instantiate(struct dentry *entry, struct inode * inode) |
| { |
| BUG_ON(!list_empty(&entry->d_alias)); |
| spin_lock(&dcache_lock); |
| if (inode) |
| list_add(&entry->d_alias, &inode->i_dentry); |
| entry->d_inode = inode; |
| fsnotify_d_instantiate(entry, inode); |
| spin_unlock(&dcache_lock); |
| security_d_instantiate(entry, inode); |
| } |
| |
| /** |
| * d_instantiate_unique - instantiate a non-aliased dentry |
| * @entry: dentry to instantiate |
| * @inode: inode to attach to this dentry |
| * |
| * Fill in inode information in the entry. On success, it returns NULL. |
| * If an unhashed alias of "entry" already exists, then we return the |
| * aliased dentry instead and drop one reference to inode. |
| * |
| * Note that in order to avoid conflicts with rename() etc, the caller |
| * had better be holding the parent directory semaphore. |
| * |
| * This also assumes that the inode count has been incremented |
| * (or otherwise set) by the caller to indicate that it is now |
| * in use by the dcache. |
| */ |
| struct dentry *d_instantiate_unique(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; |
| |
| BUG_ON(!list_empty(&entry->d_alias)); |
| spin_lock(&dcache_lock); |
| if (!inode) |
| goto do_negative; |
| list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
| struct qstr *qstr = &alias->d_name; |
| |
| if (qstr->hash != hash) |
| continue; |
| if (alias->d_parent != entry->d_parent) |
| continue; |
| if (qstr->len != len) |
| continue; |
| if (memcmp(qstr->name, name, len)) |
| continue; |
| dget_locked(alias); |
| spin_unlock(&dcache_lock); |
| BUG_ON(!d_unhashed(alias)); |
| iput(inode); |
| return alias; |
| } |
| list_add(&entry->d_alias, &inode->i_dentry); |
| do_negative: |
| entry->d_inode = inode; |
| fsnotify_d_instantiate(entry, inode); |
| spin_unlock(&dcache_lock); |
| security_d_instantiate(entry, inode); |
| return NULL; |
| } |
| EXPORT_SYMBOL(d_instantiate_unique); |
| |
| /** |
| * d_alloc_root - allocate root dentry |
| * @root_inode: inode to allocate the root for |
| * |
| * Allocate a root ("/") dentry for the inode given. The inode is |
| * instantiated and returned. %NULL is returned if there is insufficient |
| * memory or the inode passed is %NULL. |
| */ |
| |
| struct dentry * d_alloc_root(struct inode * root_inode) |
| { |
| struct dentry *res = NULL; |
| |
| if (root_inode) { |
| static const struct qstr name = { .name = "/", .len = 1 }; |
| |
| res = d_alloc(NULL, &name); |
| if (res) { |
| res->d_sb = root_inode->i_sb; |
| res->d_parent = res; |
| d_instantiate(res, root_inode); |
| } |
| } |
| return res; |
| } |
| |
| static inline struct hlist_head *d_hash(struct dentry *parent, |
| unsigned long hash) |
| { |
| hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; |
| hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); |
| return dentry_hashtable + (hash & D_HASHMASK); |
| } |
| |
| /** |
| * d_alloc_anon - allocate an anonymous dentry |
| * @inode: inode to allocate the dentry for |
| * |
| * This is similar to d_alloc_root. It is used by filesystems when |
| * creating a dentry for a given inode, often in the process of |
| * mapping a filehandle to a dentry. The returned dentry may be |
| * anonymous, or may have a full name (if the inode was already |
| * in the cache). The file system may need to make further |
| * efforts to connect this dentry into the dcache properly. |
| * |
| * When called on a directory inode, we must ensure that |
| * the inode only ever has one dentry. If a dentry is |
| * found, that is returned instead of allocating a new one. |
| * |
| * On successful return, the reference to the inode has been transferred |
| * to the dentry. If %NULL is returned (indicating kmalloc failure), |
| * the reference on the inode has not been released. |
| */ |
| |
| struct dentry * d_alloc_anon(struct inode *inode) |
| { |
| static const struct qstr anonstring = { .name = "" }; |
| struct dentry *tmp; |
| struct dentry *res; |
| |
| if ((res = d_find_alias(inode))) { |
| iput(inode); |
| return res; |
| } |
| |
| tmp = d_alloc(NULL, &anonstring); |
| if (!tmp) |
| return NULL; |
| |
| tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
| |
| spin_lock(&dcache_lock); |
| res = __d_find_alias(inode, 0); |
| if (!res) { |
| /* attach a disconnected dentry */ |
| res = tmp; |
| tmp = NULL; |
| spin_lock(&res->d_lock); |
| res->d_sb = inode->i_sb; |
| res->d_parent = res; |
| res->d_inode = inode; |
| res->d_flags |= DCACHE_DISCONNECTED; |
| res->d_flags &= ~DCACHE_UNHASHED; |
| list_add(&res->d_alias, &inode->i_dentry); |
| hlist_add_head(&res->d_hash, &inode->i_sb->s_anon); |
| spin_unlock(&res->d_lock); |
| |
| inode = NULL; /* don't drop reference */ |
| } |
| spin_unlock(&dcache_lock); |
| |
| if (inode) |
| iput(inode); |
| if (tmp) |
| dput(tmp); |
| return res; |
| } |
| |
| |
| /** |
| * d_splice_alias - splice a disconnected dentry into the tree if one exists |
| * @inode: the inode which may have a disconnected dentry |
| * @dentry: a negative dentry which we want to point to the inode. |
| * |
| * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and |
| * DCACHE_DISCONNECTED), then d_move that in place of the given dentry |
| * and return it, else simply d_add the inode to the dentry and return NULL. |
| * |
| * This is needed in the lookup routine of any filesystem that is exportable |
| * (via knfsd) so that we can build dcache paths to directories effectively. |
| * |
| * If a dentry was found and moved, then it is returned. Otherwise NULL |
| * is returned. This matches the expected return value of ->lookup. |
| * |
| */ |
| struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
| { |
| struct dentry *new = NULL; |
| |
| if (inode) { |
| spin_lock(&dcache_lock); |
| new = __d_find_alias(inode, 1); |
| if (new) { |
| BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
| fsnotify_d_instantiate(new, inode); |
| spin_unlock(&dcache_lock); |
| security_d_instantiate(new, inode); |
| d_rehash(dentry); |
| d_move(new, dentry); |
| iput(inode); |
| } else { |
| /* d_instantiate takes dcache_lock, so we do it by hand */ |
| list_add(&dentry->d_alias, &inode->i_dentry); |
| dentry->d_inode = inode; |
| fsnotify_d_instantiate(dentry, inode); |
| spin_unlock(&dcache_lock); |
| security_d_instantiate(dentry, inode); |
| d_rehash(dentry); |
| } |
| } else |
| d_add(dentry, inode); |
| return new; |
| } |
| |
| |
| /** |
| * d_lookup - search for a dentry |
| * @parent: parent dentry |
| * @name: qstr of name we wish to find |
| * |
| * Searches the children of the parent dentry for the name in question. If |
| * the dentry is found its reference count is incremented and the dentry |
| * is returned. The caller must use d_put to free the entry when it has |
| * finished using it. %NULL is returned on failure. |
| * |
| * __d_lookup is dcache_lock free. The hash list is protected using RCU. |
| * Memory barriers are used while updating and doing lockless traversal. |
| * To avoid races with d_move while rename is happening, d_lock is used. |
| * |
| * Overflows in memcmp(), while d_move, are avoided by keeping the length |
| * and name pointer in one structure pointed by d_qstr. |
| * |
| * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while |
| * lookup is going on. |
| * |
| * dentry_unused list is not updated even if lookup finds the required dentry |
| * in there. It is updated in places such as prune_dcache, shrink_dcache_sb, |
| * select_parent and __dget_locked. This laziness saves lookup from dcache_lock |
| * acquisition. |
| * |
| * d_lookup() is protected against the concurrent renames in some unrelated |
| * directory using the seqlockt_t rename_lock. |
| */ |
| |
| struct dentry * d_lookup(struct dentry * parent, struct qstr * name) |
| { |
| struct dentry * dentry = NULL; |
| unsigned long seq; |
| |
| do { |
| seq = read_seqbegin(&rename_lock); |
| dentry = __d_lookup(parent, name); |
| if (dentry) |
| break; |
| } while (read_seqretry(&rename_lock, seq)); |
| return dentry; |
| } |
| |
| struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) |
| { |
| unsigned int len = name->len; |
| unsigned int hash = name->hash; |
| const unsigned char *str = name->name; |
| struct hlist_head *head = d_hash(parent,hash); |
| struct dentry *found = NULL; |
| struct hlist_node *node; |
| struct dentry *dentry; |
| |
| rcu_read_lock(); |
| |
| hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
| struct qstr *qstr; |
| |
| if (dentry->d_name.hash != hash) |
| continue; |
| if (dentry->d_parent != parent) |
| continue; |
| |
| spin_lock(&dentry->d_lock); |
| |
| /* |
| * Recheck the dentry after taking the lock - d_move may have |
| * changed things. Don't bother checking the hash because we're |
| * about to compare the whole name anyway. |
| */ |
| if (dentry->d_parent != parent) |
| goto next; |
| |
| /* |
| * It is safe to compare names since d_move() cannot |
| * change the qstr (protected by d_lock). |
| */ |
| qstr = &dentry->d_name; |
| if (parent->d_op && parent->d_op->d_compare) { |
| if (parent->d_op->d_compare(parent, qstr, name)) |
| goto next; |
| } else { |
| if (qstr->len != len) |
| goto next; |
| if (memcmp(qstr->name, str, len)) |
| goto next; |
| } |
| |
| if (!d_unhashed(dentry)) { |
| atomic_inc(&dentry->d_count); |
| found = dentry; |
| } |
| spin_unlock(&dentry->d_lock); |
| break; |
| next: |
| spin_unlock(&dentry->d_lock); |
| } |
| rcu_read_unlock(); |
| |
| return found; |
| } |
| |
| /** |
| * d_validate - verify dentry provided from insecure source |
| * @dentry: The dentry alleged to be valid child of @dparent |
| * @dparent: The parent dentry (known to be valid) |
| * @hash: Hash of the dentry |
| * @len: Length of the name |
| * |
| * An insecure source has sent us a dentry, here we verify it and dget() it. |
| * This is used by ncpfs in its readdir implementation. |
| * Zero is returned in the dentry is invalid. |
| */ |
| |
| int d_validate(struct dentry *dentry, struct dentry *dparent) |
| { |
| struct hlist_head *base; |
| struct hlist_node *lhp; |
| |
| /* Check whether the ptr might be valid at all.. */ |
| if (!kmem_ptr_validate(dentry_cache, dentry)) |
| goto out; |
| |
| if (dentry->d_parent != dparent) |
| goto out; |
| |
| spin_lock(&dcache_lock); |
| base = d_hash(dparent, dentry->d_name.hash); |
| hlist_for_each(lhp,base) { |
| /* hlist_for_each_entry_rcu() not required for d_hash list |
| * as it is parsed under dcache_lock |
| */ |
| if (dentry == hlist_entry(lhp, struct dentry, d_hash)) { |
| __dget_locked(dentry); |
| spin_unlock(&dcache_lock); |
| return 1; |
| } |
| } |
| spin_unlock(&dcache_lock); |
| out: |
| return 0; |
| } |
| |
| /* |
| * When a file is deleted, we have two options: |
| * - turn this dentry into a negative dentry |
| * - unhash this dentry and free it. |
| * |
| * Usually, we want to just turn this into |
| * a negative dentry, but if anybody else is |
| * currently using the dentry or the inode |
| * we can't do that and we fall back on removing |
| * it from the hash queues and waiting for |
| * it to be deleted later when it has no users |
| */ |
| |
| /** |
| * d_delete - delete a dentry |
| * @dentry: The dentry to delete |
| * |
| * Turn the dentry into a negative dentry if possible, otherwise |
| * remove it from the hash queues so it can be deleted later |
| */ |
| |
| void d_delete(struct dentry * dentry) |
| { |
| int isdir = 0; |
| /* |
| * Are we the only user? |
| */ |
| spin_lock(&dcache_lock); |
| spin_lock(&dentry->d_lock); |
| isdir = S_ISDIR(dentry->d_inode->i_mode); |
| if (atomic_read(&dentry->d_count) == 1) { |
| /* remove this and other inotify debug checks after 2.6.18 */ |
| dentry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED; |
| |
| dentry_iput(dentry); |
| fsnotify_nameremove(dentry, isdir); |
| return; |
| } |
| |
| if (!d_unhashed(dentry)) |
| __d_drop(dentry); |
| |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_lock); |
| |
| fsnotify_nameremove(dentry, isdir); |
| } |
| |
| static void __d_rehash(struct dentry * entry, struct hlist_head *list) |
| { |
| |
| entry->d_flags &= ~DCACHE_UNHASHED; |
| hlist_add_head_rcu(&entry->d_hash, list); |
| } |
| |
| /** |
| * d_rehash - add an entry back to the hash |
| * @entry: dentry to add to the hash |
| * |
| * Adds a dentry to the hash according to its name. |
| */ |
| |
| void d_rehash(struct dentry * entry) |
| { |
| struct hlist_head *list = d_hash(entry->d_parent, entry->d_name.hash); |
| |
| spin_lock(&dcache_lock); |
| spin_lock(&entry->d_lock); |
| __d_rehash(entry, list); |
| spin_unlock(&entry->d_lock); |
| spin_unlock(&dcache_lock); |
| } |
| |
| #define do_switch(x,y) do { \ |
| __typeof__ (x) __tmp = x; \ |
| x = y; y = __tmp; } while (0) |
| |
| /* |
| * 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. |
| * |
| * Note that we have to be a lot more careful about getting the hash |
| * switched - we have to switch the hash value properly even if it |
| * then no longer matches the actual (corrupted) string of the target. |
| * The hash value has to match the hash queue that the dentry is on.. |
| */ |
| static void switch_names(struct dentry *dentry, struct dentry *target) |
| { |
| if (dname_external(target)) { |
| if (dname_external(dentry)) { |
| /* |
| * Both external: swap the pointers |
| */ |
| do_switch(target->d_name.name, dentry->d_name.name); |
| } else { |
| /* |
| * dentry:internal, target:external. Steal target's |
| * storage and make target internal. |
| */ |
| dentry->d_name.name = target->d_name.name; |
| target->d_name.name = target->d_iname; |
| } |
| } else { |
| if (dname_external(dentry)) { |
| /* |
| * dentry:external, target:internal. Give dentry's |
| * storage to target and make dentry internal |
| */ |
| memcpy(dentry->d_iname, target->d_name.name, |
| target->d_name.len + 1); |
| target->d_name.name = dentry->d_name.name; |
| dentry->d_name.name = dentry->d_iname; |
| } else { |
| /* |
| * Both are internal. Just copy target to dentry |
| */ |
| memcpy(dentry->d_iname, target->d_name.name, |
| target->d_name.len + 1); |
| } |
| } |
| } |
| |
| /* |
| * We cannibalize "target" when moving dentry on top of it, |
| * because it's going to be thrown away anyway. We could be more |
| * polite about it, though. |
| * |
| * This forceful removal will result in ugly /proc output if |
| * somebody holds a file open that got deleted due to a rename. |
| * We could be nicer about the deleted file, and let it show |
| * up under the name it got deleted rather than the name that |
| * deleted it. |
| */ |
| |
| /** |
| * d_move - move a dentry |
| * @dentry: entry to move |
| * @target: new dentry |
| * |
| * Update the dcache to reflect the move of a file name. Negative |
| * dcache entries should not be moved in this way. |
| */ |
| |
| void d_move(struct dentry * dentry, struct dentry * target) |
| { |
| struct hlist_head *list; |
| |
| if (!dentry->d_inode) |
| printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
| |
| spin_lock(&dcache_lock); |
| write_seqlock(&rename_lock); |
| /* |
| * XXXX: do we really need to take target->d_lock? |
| */ |
| if (target < dentry) { |
| spin_lock(&target->d_lock); |
| spin_lock(&dentry->d_lock); |
| } else { |
| spin_lock(&dentry->d_lock); |
| spin_lock(&target->d_lock); |
| } |
| |
| /* Move the dentry to the target hash queue, if on different bucket */ |
| if (dentry->d_flags & DCACHE_UNHASHED) |
| goto already_unhashed; |
| |
| hlist_del_rcu(&dentry->d_hash); |
| |
| already_unhashed: |
| list = d_hash(target->d_parent, target->d_name.hash); |
| __d_rehash(dentry, list); |
| |
| /* Unhash the target: dput() will then get rid of it */ |
| __d_drop(target); |
| |
| list_del(&dentry->d_u.d_child); |
| list_del(&target->d_u.d_child); |
| |
| /* Switch the names.. */ |
| switch_names(dentry, target); |
| do_switch(dentry->d_name.len, target->d_name.len); |
| do_switch(dentry->d_name.hash, target->d_name.hash); |
| |
| /* ... and switch the parents */ |
| if (IS_ROOT(dentry)) { |
| dentry->d_parent = target->d_parent; |
| target->d_parent = target; |
| INIT_LIST_HEAD(&target->d_u.d_child); |
| } else { |
| do_switch(dentry->d_parent, target->d_parent); |
| |
| /* And add them back to the (new) parent lists */ |
| list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
| } |
| |
| list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
| spin_unlock(&target->d_lock); |
| fsnotify_d_move(dentry); |
| spin_unlock(&dentry->d_lock); |
| write_sequnlock(&rename_lock); |
| spin_unlock(&dcache_lock); |
| } |
| |
| /** |
| * d_path - return the path of a dentry |
| * @dentry: dentry to report |
| * @vfsmnt: vfsmnt to which the dentry belongs |
| * @root: root dentry |
| * @rootmnt: vfsmnt to which the root dentry belongs |
| * @buffer: 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 the buffer or an error code if the path was too long. |
| * |
| * "buflen" should be positive. Caller holds the dcache_lock. |
| */ |
| static char * __d_path( struct dentry *dentry, struct vfsmount *vfsmnt, |
| struct dentry *root, struct vfsmount *rootmnt, |
| char *buffer, int buflen) |
| { |
| char * end = buffer+buflen; |
| char * retval; |
| int namelen; |
| |
| *--end = '\0'; |
| buflen--; |
| if (!IS_ROOT(dentry) && d_unhashed(dentry)) { |
| buflen -= 10; |
| end -= 10; |
| if (buflen < 0) |
| goto Elong; |
| memcpy(end, " (deleted)", 10); |
| } |
| |
| if (buflen < 1) |
| goto Elong; |
| /* Get '/' right */ |
| retval = end-1; |
| *retval = '/'; |
| |
| for (;;) { |
| struct dentry * parent; |
| |
| if (dentry == root && vfsmnt == rootmnt) |
| break; |
| if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
| /* Global root? */ |
| spin_lock(&vfsmount_lock); |
| if (vfsmnt->mnt_parent == vfsmnt) { |
| spin_unlock(&vfsmount_lock); |
| goto global_root; |
| } |
| dentry = vfsmnt->mnt_mountpoint; |
| vfsmnt = vfsmnt->mnt_parent; |
| spin_unlock(&vfsmount_lock); |
| continue; |
| } |
| parent = dentry->d_parent; |
| prefetch(parent); |
| namelen = dentry->d_name.len; |
| buflen -= namelen + 1; |
| if (buflen < 0) |
| goto Elong; |
| end -= namelen; |
| memcpy(end, dentry->d_name.name, namelen); |
| *--end = '/'; |
| retval = end; |
| dentry = parent; |
| } |
| |
| return retval; |
| |
| global_root: |
| namelen = dentry->d_name.len; |
| buflen -= namelen; |
| if (buflen < 0) |
| goto Elong; |
| retval -= namelen-1; /* hit the slash */ |
| memcpy(retval, dentry->d_name.name, namelen); |
| return retval; |
| Elong: |
| return ERR_PTR(-ENAMETOOLONG); |
| } |
| |
| /* write full pathname into buffer and return start of pathname */ |
| char * d_path(struct dentry *dentry, struct vfsmount *vfsmnt, |
| char *buf, int buflen) |
| { |
| char *res; |
| struct vfsmount *rootmnt; |
| struct dentry *root; |
| |
| read_lock(¤t->fs->lock); |
| rootmnt = mntget(current->fs->rootmnt); |
| root = dget(current->fs->root); |
| read_unlock(¤t->fs->lock); |
| spin_lock(&dcache_lock); |
| res = __d_path(dentry, vfsmnt, root, rootmnt, buf, buflen); |
| spin_unlock(&dcache_lock); |
| dput(root); |
| mntput(rootmnt); |
| return res; |
| } |
| |
| /* |
| * 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; |
| * } |
| */ |
| asmlinkage long sys_getcwd(char __user *buf, unsigned long size) |
| { |
| int error; |
| struct vfsmount *pwdmnt, *rootmnt; |
| struct dentry *pwd, *root; |
| char *page = (char *) __get_free_page(GFP_USER); |
| |
| if (!page) |
| return -ENOMEM; |
| |
| read_lock(¤t->fs->lock); |
| pwdmnt = mntget(current->fs->pwdmnt); |
| pwd = dget(current->fs->pwd); |
| rootmnt = mntget(current->fs->rootmnt); |
| root = dget(current->fs->root); |
| read_unlock(¤t->fs->lock); |
| |
| error = -ENOENT; |
| /* Has the current directory has been unlinked? */ |
| spin_lock(&dcache_lock); |
| if (pwd->d_parent == pwd || !d_unhashed(pwd)) { |
| unsigned long len; |
| char * cwd; |
| |
| cwd = __d_path(pwd, pwdmnt, root, rootmnt, page, PAGE_SIZE); |
| spin_unlock(&dcache_lock); |
| |
| error = PTR_ERR(cwd); |
| if (IS_ERR(cwd)) |
| goto out; |
| |
| error = -ERANGE; |
| len = PAGE_SIZE + page - cwd; |
| if (len <= size) { |
| error = len; |
| if (copy_to_user(buf, cwd, len)) |
| error = -EFAULT; |
| } |
| } else |
| spin_unlock(&dcache_lock); |
| |
| out: |
| dput(pwd); |
| mntput(pwdmnt); |
| dput(root); |
| mntput(rootmnt); |
| free_page((unsigned long) page); |
| return error; |
| } |
| |
| /* |
| * Test whether new_dentry is a subdirectory of old_dentry. |
| * |
| * Trivially implemented using the dcache structure |
| */ |
| |
| /** |
| * is_subdir - is new dentry a subdirectory of old_dentry |
| * @new_dentry: new dentry |
| * @old_dentry: old dentry |
| * |
| * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). |
| * Returns 0 otherwise. |
| * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
| */ |
| |
| int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry) |
| { |
| int result; |
| struct dentry * saved = new_dentry; |
| unsigned long seq; |
| |
| /* need rcu_readlock to protect against the d_parent trashing due to |
| * d_move |
| */ |
| rcu_read_lock(); |
| do { |
| /* for restarting inner loop in case of seq retry */ |
| new_dentry = saved; |
| result = 0; |
| seq = read_seqbegin(&rename_lock); |
| for (;;) { |
| if (new_dentry != old_dentry) { |
| struct dentry * parent = new_dentry->d_parent; |
| if (parent == new_dentry) |
| break; |
| new_dentry = parent; |
| continue; |
| } |
| result = 1; |
| break; |
| } |
| } while (read_seqretry(&rename_lock, seq)); |
| rcu_read_unlock(); |
| |
| return result; |
| } |
| |
| void d_genocide(struct dentry *root) |
| { |
| struct dentry *this_parent = root; |
| struct list_head *next; |
| |
| spin_lock(&dcache_lock); |
| repeat: |
| next = this_parent->d_subdirs.next; |
| resume: |
| while (next != &this_parent->d_subdirs) { |
| struct list_head *tmp = next; |
| struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
| next = tmp->next; |
| if (d_unhashed(dentry)||!dentry->d_inode) |
| continue; |
| if (!list_empty(&dentry->d_subdirs)) { |
| this_parent = dentry; |
| goto repeat; |
| } |
| atomic_dec(&dentry->d_count); |
| } |
| if (this_parent != root) { |
| next = this_parent->d_u.d_child.next; |
| atomic_dec(&this_parent->d_count); |
| this_parent = this_parent->d_parent; |
| goto resume; |
| } |
| spin_unlock(&dcache_lock); |
| } |
| |
| /** |
| * find_inode_number - check for dentry with name |
| * @dir: directory to check |
| * @name: Name to find. |
| * |
| * Check whether a dentry already exists for the given name, |
| * and return the inode number if it has an inode. Otherwise |
| * 0 is returned. |
| * |
| * This routine is used to post-process directory listings for |
| * filesystems using synthetic inode numbers, and is necessary |
| * to keep getcwd() working. |
| */ |
| |
| ino_t find_inode_number(struct dentry *dir, struct qstr *name) |
| { |
| struct dentry * dentry; |
| ino_t ino = 0; |
| |
| /* |
| * Check for a fs-specific hash function. Note that we must |
| * 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); |
| if (dir->d_op && dir->d_op->d_hash) |
| { |
| if (dir->d_op->d_hash(dir, name) != 0) |
| goto out; |
| } |
| |
| dentry = d_lookup(dir, name); |
| if (dentry) |
| { |
| if (dentry->d_inode) |
| ino = dentry->d_inode->i_ino; |
| dput(dentry); |
| } |
| out: |
| return ino; |
| } |
| |
| static __initdata unsigned long dhash_entries; |
| static int __init set_dhash_entries(char *str) |
| { |
| if (!str) |
| return 0; |
| dhash_entries = simple_strtoul(str, &str, 0); |
| return 1; |
| } |
| __setup("dhash_entries=", set_dhash_entries); |
| |
| static void __init dcache_init_early(void) |
| { |
| int loop; |
| |
| /* If hashes are distributed across NUMA nodes, defer |
| * hash allocation until vmalloc space is available. |
| */ |
| if (hashdist) |
| return; |
| |
| dentry_hashtable = |
| alloc_large_system_hash("Dentry cache", |
| sizeof(struct hlist_head), |
| dhash_entries, |
| 13, |
| HASH_EARLY, |
| &d_hash_shift, |
| &d_hash_mask, |
| 0); |
| |
| for (loop = 0; loop < (1 << d_hash_shift); loop++) |
| INIT_HLIST_HEAD(&dentry_hashtable[loop]); |
| } |
| |
| static void __init dcache_init(unsigned long mempages) |
| { |
| int loop; |
| |
| /* |
| * A constructor could be added for stable state like the lists, |
| * but it is probably not worth it because of the cache nature |
| * of the dcache. |
| */ |
| dentry_cache = kmem_cache_create("dentry_cache", |
| sizeof(struct dentry), |
| 0, |
| (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| |
| SLAB_MEM_SPREAD), |
| NULL, NULL); |
| |
| set_shrinker(DEFAULT_SEEKS, shrink_dcache_memory); |
| |
| /* Hash may have been set up in dcache_init_early */ |
| if (!hashdist) |
| return; |
| |
| dentry_hashtable = |
| alloc_large_system_hash("Dentry cache", |
| sizeof(struct hlist_head), |
| dhash_entries, |
| 13, |
| 0, |
| &d_hash_shift, |
| &d_hash_mask, |
| 0); |
| |
| for (loop = 0; loop < (1 << d_hash_shift); loop++) |
| INIT_HLIST_HEAD(&dentry_hashtable[loop]); |
| } |
| |
| /* SLAB cache for __getname() consumers */ |
| kmem_cache_t *names_cachep; |
| |
| /* SLAB cache for file structures */ |
| kmem_cache_t *filp_cachep; |
| |
| EXPORT_SYMBOL(d_genocide); |
| |
| extern void bdev_cache_init(void); |
| extern void chrdev_init(void); |
| |
| void __init vfs_caches_init_early(void) |
| { |
| dcache_init_early(); |
| inode_init_early(); |
| } |
| |
| void __init vfs_caches_init(unsigned long mempages) |
| { |
| unsigned long reserve; |
| |
| /* Base hash sizes on available memory, with a reserve equal to |
| 150% of current kernel size */ |
| |
| reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); |
| mempages -= reserve; |
| |
| names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
| SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); |
| |
| filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, |
| SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); |
| |
| dcache_init(mempages); |
| inode_init(mempages); |
| files_init(mempages); |
| mnt_init(mempages); |
| bdev_cache_init(); |
| chrdev_init(); |
| } |
| |
| EXPORT_SYMBOL(d_alloc); |
| EXPORT_SYMBOL(d_alloc_anon); |
| EXPORT_SYMBOL(d_alloc_root); |
| EXPORT_SYMBOL(d_delete); |
| EXPORT_SYMBOL(d_find_alias); |
| EXPORT_SYMBOL(d_instantiate); |
| EXPORT_SYMBOL(d_invalidate); |
| EXPORT_SYMBOL(d_lookup); |
| EXPORT_SYMBOL(d_move); |
| EXPORT_SYMBOL(d_path); |
| EXPORT_SYMBOL(d_prune_aliases); |
| EXPORT_SYMBOL(d_rehash); |
| EXPORT_SYMBOL(d_splice_alias); |
| EXPORT_SYMBOL(d_validate); |
| EXPORT_SYMBOL(dget_locked); |
| EXPORT_SYMBOL(dput); |
| EXPORT_SYMBOL(find_inode_number); |
| EXPORT_SYMBOL(have_submounts); |
| EXPORT_SYMBOL(names_cachep); |
| EXPORT_SYMBOL(shrink_dcache_parent); |
| EXPORT_SYMBOL(shrink_dcache_sb); |