| /* |
| * 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/string.h> |
| #include <linux/mm.h> |
| #include <linux/fs.h> |
| #include <linux/slab.h> |
| #include <linux/init.h> |
| #include <linux/smp_lock.h> |
| #include <linux/cache.h> |
| #include <linux/module.h> |
| |
| #include <asm/uaccess.h> |
| |
| #define DCACHE_PARANOIA 1 |
| /* #define DCACHE_DEBUG 1 */ |
| |
| spinlock_t dcache_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED; |
| rwlock_t dparent_lock __cacheline_aligned_in_smp = RW_LOCK_UNLOCKED; |
| |
| static kmem_cache_t *dentry_cache; |
| |
| /* |
| * 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 list_head *dentry_hashtable; |
| static LIST_HEAD(dentry_unused); |
| |
| /* Statistics gathering. */ |
| struct dentry_stat_t dentry_stat = {0, 0, 45, 0,}; |
| |
| /* no dcache_lock, please */ |
| static inline void d_free(struct dentry *dentry) |
| { |
| if (dentry->d_op && dentry->d_op->d_release) |
| dentry->d_op->d_release(dentry); |
| if (dname_external(dentry)) |
| kfree(dentry->d_name.name); |
| kmem_cache_free(dentry_cache, dentry); |
| dentry_stat.nr_dentry--; |
| } |
| |
| /* |
| * Release the dentry's inode, using the fileystem |
| * d_iput() operation if defined. |
| * Called with dcache_lock held, drops it. |
| */ |
| static inline 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(&dcache_lock); |
| if (dentry->d_op && dentry->d_op->d_iput) |
| dentry->d_op->d_iput(dentry, inode); |
| else |
| iput(inode); |
| } else |
| 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_dec_and_lock(&dentry->d_count, &dcache_lock)) |
| return; |
| |
| /* dput on a free dentry? */ |
| if (!list_empty(&dentry->d_lru)) |
| BUG(); |
| /* |
| * 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 (list_empty(&dentry->d_hash)) |
| goto kill_it; |
| list_add(&dentry->d_lru, &dentry_unused); |
| dentry_stat.nr_unused++; |
| spin_unlock(&dcache_lock); |
| return; |
| |
| unhash_it: |
| list_del_init(&dentry->d_hash); |
| |
| kill_it: { |
| struct dentry *parent; |
| list_del(&dentry->d_child); |
| /* drops the lock, 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 (list_empty(&dentry->d_hash)) { |
| 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). |
| */ |
| if (atomic_read(&dentry->d_count) > 1) { |
| if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { |
| spin_unlock(&dcache_lock); |
| return -EBUSY; |
| } |
| } |
| |
| list_del_init(&dentry->d_hash); |
| 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 (atomic_read(&dentry->d_count) == 1) { |
| 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 |
| * |
| * If inode has a hashed 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. |
| * |
| * If the inode has a DCACHE_DISCONNECTED alias, then prefer |
| * any other hashed alias over that one. |
| */ |
| |
| struct dentry * d_find_alias(struct inode *inode) |
| { |
| struct list_head *head, *next, *tmp; |
| struct dentry *alias, *discon_alias=NULL; |
| |
| spin_lock(&dcache_lock); |
| head = &inode->i_dentry; |
| next = inode->i_dentry.next; |
| while (next != head) { |
| tmp = next; |
| next = tmp->next; |
| alias = list_entry(tmp, struct dentry, d_alias); |
| if (!list_empty(&alias->d_hash)) { |
| if (alias->d_flags & DCACHE_DISCONNECTED) |
| discon_alias = alias; |
| else { |
| __dget_locked(alias); |
| spin_unlock(&dcache_lock); |
| return alias; |
| } |
| } |
| } |
| if (discon_alias) |
| __dget_locked(discon_alias); |
| spin_unlock(&dcache_lock); |
| return discon_alias; |
| } |
| |
| /* |
| * Try to kill dentries associated with this inode. |
| * WARNING: you must own a reference to inode. |
| */ |
| void d_prune_aliases(struct inode *inode) |
| { |
| struct list_head *tmp, *head = &inode->i_dentry; |
| restart: |
| spin_lock(&dcache_lock); |
| tmp = head; |
| while ((tmp = tmp->next) != head) { |
| struct dentry *dentry = list_entry(tmp, struct dentry, d_alias); |
| if (!atomic_read(&dentry->d_count)) { |
| __dget_locked(dentry); |
| spin_unlock(&dcache_lock); |
| d_drop(dentry); |
| dput(dentry); |
| goto restart; |
| } |
| } |
| 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; |
| |
| list_del_init(&dentry->d_hash); |
| list_del(&dentry->d_child); |
| 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. |
| */ |
| |
| void prune_dcache(int count) |
| { |
| spin_lock(&dcache_lock); |
| for (;;) { |
| struct dentry *dentry; |
| struct list_head *tmp; |
| |
| tmp = dentry_unused.prev; |
| |
| if (tmp == &dentry_unused) |
| break; |
| list_del_init(tmp); |
| dentry = list_entry(tmp, struct dentry, d_lru); |
| |
| /* If the dentry was recently referenced, don't free it. */ |
| if (dentry->d_vfs_flags & DCACHE_REFERENCED) { |
| dentry->d_vfs_flags &= ~DCACHE_REFERENCED; |
| list_add(&dentry->d_lru, &dentry_unused); |
| continue; |
| } |
| dentry_stat.nr_unused--; |
| |
| /* Unused dentry with a count? */ |
| if (atomic_read(&dentry->d_count)) |
| BUG(); |
| |
| prune_one_dentry(dentry); |
| if (!--count) |
| break; |
| } |
| 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); |
| next = dentry_unused.next; |
| while (next != &dentry_unused) { |
| tmp = next; |
| next = tmp->next; |
| 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: |
| next = dentry_unused.next; |
| while (next != &dentry_unused) { |
| tmp = next; |
| next = tmp->next; |
| dentry = list_entry(tmp, struct dentry, d_lru); |
| if (dentry->d_sb != sb) |
| continue; |
| if (atomic_read(&dentry->d_count)) |
| continue; |
| dentry_stat.nr_unused--; |
| list_del_init(tmp); |
| prune_one_dentry(dentry); |
| 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_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_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. |
| */ |
| 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_child); |
| next = tmp->next; |
| if (!atomic_read(&dentry->d_count)) { |
| list_del(&dentry->d_lru); |
| list_add(&dentry->d_lru, dentry_unused.prev); |
| found++; |
| } |
| /* |
| * 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_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; |
| } |
| 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 |
| * |
| */ |
| void shrink_dcache_anon(struct list_head *head) |
| { |
| struct list_head *lp; |
| int found; |
| do { |
| found = 0; |
| spin_lock(&dcache_lock); |
| list_for_each(lp, head) { |
| struct dentry *this = list_entry(lp, struct dentry, d_hash); |
| if (!atomic_read(&this->d_count)) { |
| list_del(&this->d_lru); |
| list_add_tail(&this->d_lru, &dentry_unused); |
| found++; |
| } |
| } |
| spin_unlock(&dcache_lock); |
| prune_dcache(found); |
| } while(found); |
| } |
| |
| /* |
| * This is called from kswapd when we think we need some |
| * more memory, but aren't really sure how much. So we |
| * carefully try to free a _bit_ of our dcache, but not |
| * too much. |
| * |
| * Priority: |
| * 1 - very urgent: shrink everything |
| * ... |
| * 6 - base-level: try to shrink a bit. |
| */ |
| int shrink_dcache_memory(int priority, unsigned int gfp_mask) |
| { |
| int count = 0; |
| |
| /* |
| * Nasty deadlock avoidance. |
| * |
| * 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. |
| * |
| * We should make sure we don't hold the superblock lock over |
| * block allocations, but for now: |
| */ |
| if (!(gfp_mask & __GFP_FS)) |
| return 0; |
| |
| count = dentry_stat.nr_unused / priority; |
| |
| prune_dcache(count); |
| kmem_cache_shrink(dentry_cache); |
| return 0; |
| } |
| |
| #define NAME_ALLOC_LEN(len) ((len+16) & ~15) |
| |
| /** |
| * 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) |
| { |
| char * str; |
| struct dentry *dentry; |
| |
| dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
| if (!dentry) |
| return NULL; |
| |
| if (name->len > DNAME_INLINE_LEN-1) { |
| str = kmalloc(NAME_ALLOC_LEN(name->len), GFP_KERNEL); |
| if (!str) { |
| kmem_cache_free(dentry_cache, dentry); |
| return NULL; |
| } |
| } else |
| str = dentry->d_iname; |
| |
| memcpy(str, name->name, name->len); |
| str[name->len] = 0; |
| |
| atomic_set(&dentry->d_count, 1); |
| dentry->d_vfs_flags = 0; |
| dentry->d_flags = 0; |
| dentry->d_inode = NULL; |
| dentry->d_parent = NULL; |
| dentry->d_sb = NULL; |
| dentry->d_name.name = str; |
| dentry->d_name.len = name->len; |
| dentry->d_name.hash = name->hash; |
| dentry->d_op = NULL; |
| dentry->d_fsdata = NULL; |
| dentry->d_mounted = 0; |
| INIT_LIST_HEAD(&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; |
| spin_lock(&dcache_lock); |
| list_add(&dentry->d_child, &parent->d_subdirs); |
| spin_unlock(&dcache_lock); |
| } else |
| INIT_LIST_HEAD(&dentry->d_child); |
| |
| dentry_stat.nr_dentry++; |
| return dentry; |
| } |
| |
| /** |
| * 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) |
| { |
| if (!list_empty(&entry->d_alias)) BUG(); |
| spin_lock(&dcache_lock); |
| if (inode) |
| list_add(&entry->d_alias, &inode->i_dentry); |
| entry->d_inode = inode; |
| spin_unlock(&dcache_lock); |
| } |
| |
| /** |
| * 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) { |
| res = d_alloc(NULL, &(const struct qstr) { "/", 1, 0 }); |
| if (res) { |
| res->d_sb = root_inode->i_sb; |
| res->d_parent = res; |
| d_instantiate(res, root_inode); |
| } |
| } |
| return res; |
| } |
| |
| static inline struct list_head * d_hash(struct dentry * parent, unsigned long hash) |
| { |
| hash += (unsigned long) parent / L1_CACHE_BYTES; |
| hash = hash ^ (hash >> 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) |
| { |
| struct dentry *tmp; |
| struct dentry *res; |
| |
| if ((res = d_find_alias(inode))) { |
| iput(inode); |
| return res; |
| } |
| |
| tmp = d_alloc(NULL, &(const struct qstr) {"",0,0}); |
| tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
| |
| spin_lock(&dcache_lock); |
| if (S_ISDIR(inode->i_mode) && !list_empty(&inode->i_dentry)) { |
| /* A directory can only have one dentry. |
| * This (now) has one, so use it. |
| */ |
| res = list_entry(inode->i_dentry.next, struct dentry, d_alias); |
| __dget_locked(res); |
| } else { |
| /* attach a disconnected dentry */ |
| res = tmp; |
| tmp = NULL; |
| if (res) { |
| res->d_sb = inode->i_sb; |
| res->d_parent = res; |
| res->d_inode = inode; |
| res->d_flags |= DCACHE_DISCONNECTED; |
| list_add(&res->d_alias, &inode->i_dentry); |
| list_add(&res->d_hash, &inode->i_sb->s_anon); |
| } |
| 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 (will be) 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 && S_ISDIR(inode->i_mode)) { |
| spin_lock(&dcache_lock); |
| if (!list_empty(&inode->i_dentry)) { |
| new = list_entry(inode->i_dentry.next, struct dentry, d_alias); |
| __dget_locked(new); |
| spin_unlock(&dcache_lock); |
| 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; |
| spin_unlock(&dcache_lock); |
| 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. |
| */ |
| |
| struct dentry * d_lookup(struct dentry * parent, struct qstr * name) |
| { |
| struct dentry * dentry; |
| spin_lock(&dcache_lock); |
| dentry = __d_lookup(parent,name); |
| if (dentry) |
| __dget_locked(dentry); |
| spin_unlock(&dcache_lock); |
| 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 list_head *head = d_hash(parent,hash); |
| struct list_head *tmp; |
| |
| tmp = head->next; |
| for (;;) { |
| struct dentry * dentry = list_entry(tmp, struct dentry, d_hash); |
| if (tmp == head) |
| break; |
| tmp = tmp->next; |
| if (dentry->d_name.hash != hash) |
| continue; |
| if (dentry->d_parent != parent) |
| continue; |
| if (parent->d_op && parent->d_op->d_compare) { |
| if (parent->d_op->d_compare(parent, &dentry->d_name, name)) |
| continue; |
| } else { |
| if (dentry->d_name.len != len) |
| continue; |
| if (memcmp(dentry->d_name.name, str, len)) |
| continue; |
| } |
| dentry->d_vfs_flags |= DCACHE_REFERENCED; |
| return dentry; |
| } |
| return NULL; |
| } |
| |
| /** |
| * 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) |
| { |
| unsigned long dent_addr = (unsigned long) dentry; |
| unsigned long min_addr = PAGE_OFFSET; |
| unsigned long align_mask = 0x0F; |
| struct list_head *base, *lhp; |
| |
| if (dent_addr < min_addr) |
| goto out; |
| if (dent_addr > (unsigned long)high_memory - sizeof(struct dentry)) |
| goto out; |
| if (dent_addr & align_mask) |
| goto out; |
| if ((!kern_addr_valid(dent_addr)) || (!kern_addr_valid(dent_addr -1 + |
| sizeof(struct dentry)))) |
| goto out; |
| |
| if (dentry->d_parent != dparent) |
| goto out; |
| |
| spin_lock(&dcache_lock); |
| lhp = base = d_hash(dparent, dentry->d_name.hash); |
| while ((lhp = lhp->next) != base) { |
| if (dentry == list_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) |
| { |
| /* |
| * Are we the only user? |
| */ |
| spin_lock(&dcache_lock); |
| if (atomic_read(&dentry->d_count) == 1) { |
| dentry_iput(dentry); |
| return; |
| } |
| spin_unlock(&dcache_lock); |
| |
| /* |
| * If not, just drop the dentry and let dput |
| * pick up the tab.. |
| */ |
| d_drop(dentry); |
| } |
| |
| /** |
| * 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 list_head *list = d_hash(entry->d_parent, entry->d_name.hash); |
| if (!list_empty(&entry->d_hash)) BUG(); |
| spin_lock(&dcache_lock); |
| list_add(&entry->d_hash, list); |
| 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 inline void switch_names(struct dentry * dentry, struct dentry * target) |
| { |
| const unsigned char *old_name, *new_name; |
| |
| memcpy(dentry->d_iname, target->d_iname, DNAME_INLINE_LEN); |
| old_name = target->d_name.name; |
| new_name = dentry->d_name.name; |
| if (old_name == target->d_iname) |
| old_name = dentry->d_iname; |
| if (new_name == dentry->d_iname) |
| new_name = target->d_iname; |
| target->d_name.name = new_name; |
| dentry->d_name.name = old_name; |
| } |
| |
| /* |
| * 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. |
| * |
| * Careful with the hash switch. The hash switch depends on |
| * the fact that any list-entry can be a head of the list. |
| * Think about 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) |
| { |
| if (!dentry->d_inode) |
| printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
| |
| spin_lock(&dcache_lock); |
| /* Move the dentry to the target hash queue */ |
| list_del(&dentry->d_hash); |
| list_add(&dentry->d_hash, &target->d_hash); |
| |
| /* Unhash the target: dput() will then get rid of it */ |
| list_del_init(&target->d_hash); |
| |
| list_del(&dentry->d_child); |
| list_del(&target->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 */ |
| write_lock(&dparent_lock); |
| if (IS_ROOT(dentry)) { |
| dentry->d_parent = target->d_parent; |
| target->d_parent = target; |
| INIT_LIST_HEAD(&target->d_child); |
| } else { |
| do_switch(dentry->d_parent, target->d_parent); |
| |
| /* And add them back to the (new) parent lists */ |
| list_add(&target->d_child, &target->d_parent->d_subdirs); |
| } |
| write_unlock(&dparent_lock); |
| |
| list_add(&dentry->d_child, &dentry->d_parent->d_subdirs); |
| 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. |
| * |
| * "buflen" should be %PAGE_SIZE or more. Caller holds the dcache_lock. |
| */ |
| 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) && list_empty(&dentry->d_hash)) { |
| buflen -= 10; |
| end -= 10; |
| memcpy(end, " (deleted)", 10); |
| } |
| |
| /* 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? */ |
| if (vfsmnt->mnt_parent == vfsmnt) |
| goto global_root; |
| dentry = vfsmnt->mnt_mountpoint; |
| vfsmnt = vfsmnt->mnt_parent; |
| continue; |
| } |
| parent = dentry->d_parent; |
| namelen = dentry->d_name.len; |
| buflen -= namelen + 1; |
| if (buflen < 0) |
| break; |
| 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) { |
| retval -= namelen-1; /* hit the slash */ |
| memcpy(retval, dentry->d_name.name, namelen); |
| } |
| return retval; |
| } |
| |
| /* |
| * 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 *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 || !list_empty(&pwd->d_hash)) { |
| unsigned long len; |
| char * cwd; |
| |
| cwd = __d_path(pwd, pwdmnt, root, rootmnt, page, PAGE_SIZE); |
| spin_unlock(&dcache_lock); |
| |
| 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); |
| 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. |
| */ |
| |
| int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry) |
| { |
| int result; |
| |
| result = 0; |
| 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; |
| } |
| 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_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_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 void __init dcache_init(unsigned long mempages) |
| { |
| struct list_head *d; |
| unsigned long order; |
| unsigned int nr_hash; |
| int i; |
| |
| /* |
| * 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. |
| * If fragmentation is too bad then the SLAB_HWCACHE_ALIGN |
| * flag could be removed here, to hint to the allocator that |
| * it should not try to get multiple page regions. |
| */ |
| dentry_cache = kmem_cache_create("dentry_cache", |
| sizeof(struct dentry), |
| 0, |
| SLAB_HWCACHE_ALIGN, |
| NULL, NULL); |
| if (!dentry_cache) |
| panic("Cannot create dentry cache"); |
| |
| #if PAGE_SHIFT < 13 |
| mempages >>= (13 - PAGE_SHIFT); |
| #endif |
| mempages *= sizeof(struct list_head); |
| for (order = 0; ((1UL << order) << PAGE_SHIFT) < mempages; order++) |
| ; |
| |
| do { |
| unsigned long tmp; |
| |
| nr_hash = (1UL << order) * PAGE_SIZE / |
| sizeof(struct list_head); |
| d_hash_mask = (nr_hash - 1); |
| |
| tmp = nr_hash; |
| d_hash_shift = 0; |
| while ((tmp >>= 1UL) != 0UL) |
| d_hash_shift++; |
| |
| dentry_hashtable = (struct list_head *) |
| __get_free_pages(GFP_ATOMIC, order); |
| } while (dentry_hashtable == NULL && --order >= 0); |
| |
| printk("Dentry-cache hash table entries: %d (order: %ld, %ld bytes)\n", |
| nr_hash, order, (PAGE_SIZE << order)); |
| |
| if (!dentry_hashtable) |
| panic("Failed to allocate dcache hash table\n"); |
| |
| d = dentry_hashtable; |
| i = nr_hash; |
| do { |
| INIT_LIST_HEAD(d); |
| d++; |
| i--; |
| } while (i); |
| } |
| |
| /* SLAB cache for __getname() consumers */ |
| kmem_cache_t *names_cachep; |
| |
| /* SLAB cache for file structures */ |
| kmem_cache_t *filp_cachep; |
| |
| /* SLAB cache for dquot structures */ |
| kmem_cache_t *dquot_cachep; |
| |
| EXPORT_SYMBOL(d_genocide); |
| |
| extern void bdev_cache_init(void); |
| extern void cdev_cache_init(void); |
| |
| void __init vfs_caches_init(unsigned long mempages) |
| { |
| names_cachep = kmem_cache_create("names_cache", |
| PATH_MAX, 0, |
| SLAB_HWCACHE_ALIGN, NULL, NULL); |
| if (!names_cachep) |
| panic("Cannot create names SLAB cache"); |
| |
| filp_cachep = kmem_cache_create("filp", |
| sizeof(struct file), 0, |
| SLAB_HWCACHE_ALIGN, NULL, NULL); |
| if(!filp_cachep) |
| panic("Cannot create filp SLAB cache"); |
| |
| #if defined (CONFIG_QUOTA) |
| dquot_cachep = kmem_cache_create("dquot", |
| sizeof(struct dquot), sizeof(unsigned long) * 4, |
| SLAB_HWCACHE_ALIGN, NULL, NULL); |
| if (!dquot_cachep) |
| panic("Cannot create dquot SLAB cache"); |
| #endif |
| |
| dcache_init(mempages); |
| inode_init(mempages); |
| files_init(mempages); |
| mnt_init(mempages); |
| bdev_cache_init(); |
| cdev_cache_init(); |
| } |