| /* |
| * 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/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/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> |
| #include <linux/fs_struct.h> |
| #include <linux/hardirq.h> |
| #include "internal.h" |
| |
| /* |
| * Usage: |
| * dcache_inode_lock protects: |
| * - i_dentry, d_alias, d_inode |
| * dcache_hash_lock protects: |
| * - the dcache hash table, s_anon lists |
| * dcache_lru_lock protects: |
| * - the dcache lru lists and counters |
| * d_lock protects: |
| * - d_flags |
| * - d_name |
| * - d_lru |
| * - d_count |
| * - d_unhashed() |
| * - d_parent and d_subdirs |
| * - childrens' d_child and d_parent |
| * - d_alias, d_inode |
| * |
| * Ordering: |
| * dcache_inode_lock |
| * dentry->d_lock |
| * dcache_lru_lock |
| * dcache_hash_lock |
| * |
| * If there is an ancestor relationship: |
| * dentry->d_parent->...->d_parent->d_lock |
| * ... |
| * dentry->d_parent->d_lock |
| * dentry->d_lock |
| * |
| * If no ancestor relationship: |
| * if (dentry1 < dentry2) |
| * dentry1->d_lock |
| * dentry2->d_lock |
| */ |
| int sysctl_vfs_cache_pressure __read_mostly = 100; |
| EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
| |
| __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_inode_lock); |
| static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock); |
| static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); |
| __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
| |
| EXPORT_SYMBOL(rename_lock); |
| EXPORT_SYMBOL(dcache_inode_lock); |
| |
| static struct kmem_cache *dentry_cache __read_mostly; |
| |
| #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 __read_mostly; |
| static unsigned int d_hash_shift __read_mostly; |
| static struct hlist_head *dentry_hashtable __read_mostly; |
| |
| /* Statistics gathering. */ |
| struct dentry_stat_t dentry_stat = { |
| .age_limit = 45, |
| }; |
| |
| static DEFINE_PER_CPU(unsigned int, nr_dentry); |
| |
| #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
| static int get_nr_dentry(void) |
| { |
| int i; |
| int sum = 0; |
| for_each_possible_cpu(i) |
| sum += per_cpu(nr_dentry, i); |
| return sum < 0 ? 0 : sum; |
| } |
| |
| int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
| size_t *lenp, loff_t *ppos) |
| { |
| dentry_stat.nr_dentry = get_nr_dentry(); |
| return proc_dointvec(table, write, buffer, lenp, ppos); |
| } |
| #endif |
| |
| static void __d_free(struct rcu_head *head) |
| { |
| struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
| |
| WARN_ON(!list_empty(&dentry->d_alias)); |
| if (dname_external(dentry)) |
| kfree(dentry->d_name.name); |
| kmem_cache_free(dentry_cache, dentry); |
| } |
| |
| /* |
| * no locks, please. |
| */ |
| static void d_free(struct dentry *dentry) |
| { |
| BUG_ON(dentry->d_count); |
| this_cpu_dec(nr_dentry); |
| if (dentry->d_op && dentry->d_op->d_release) |
| dentry->d_op->d_release(dentry); |
| |
| /* if dentry was never inserted into hash, immediate free is OK */ |
| if (hlist_unhashed(&dentry->d_hash)) |
| __d_free(&dentry->d_u.d_rcu); |
| else |
| call_rcu(&dentry->d_u.d_rcu, __d_free); |
| } |
| |
| /* |
| * Release the dentry's inode, using the filesystem |
| * d_iput() operation if defined. |
| */ |
| static void dentry_iput(struct dentry * dentry) |
| __releases(dentry->d_lock) |
| __releases(dcache_inode_lock) |
| { |
| 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_inode_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_inode_lock); |
| } |
| } |
| |
| /* |
| * dentry_lru_(add|del|move_tail) must be called with d_lock held. |
| */ |
| static void dentry_lru_add(struct dentry *dentry) |
| { |
| if (list_empty(&dentry->d_lru)) { |
| spin_lock(&dcache_lru_lock); |
| list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
| dentry->d_sb->s_nr_dentry_unused++; |
| dentry_stat.nr_unused++; |
| spin_unlock(&dcache_lru_lock); |
| } |
| } |
| |
| static void __dentry_lru_del(struct dentry *dentry) |
| { |
| list_del_init(&dentry->d_lru); |
| dentry->d_sb->s_nr_dentry_unused--; |
| dentry_stat.nr_unused--; |
| } |
| |
| static void dentry_lru_del(struct dentry *dentry) |
| { |
| if (!list_empty(&dentry->d_lru)) { |
| spin_lock(&dcache_lru_lock); |
| __dentry_lru_del(dentry); |
| spin_unlock(&dcache_lru_lock); |
| } |
| } |
| |
| static void dentry_lru_move_tail(struct dentry *dentry) |
| { |
| spin_lock(&dcache_lru_lock); |
| if (list_empty(&dentry->d_lru)) { |
| list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
| dentry->d_sb->s_nr_dentry_unused++; |
| dentry_stat.nr_unused++; |
| } else { |
| list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
| } |
| spin_unlock(&dcache_lru_lock); |
| } |
| |
| /** |
| * d_kill - kill dentry and return parent |
| * @dentry: dentry to kill |
| * |
| * The dentry must already be unhashed and removed from the LRU. |
| * |
| * If this is the root of the dentry tree, return NULL. |
| * |
| * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by |
| * d_kill. |
| */ |
| static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) |
| __releases(dentry->d_lock) |
| __releases(parent->d_lock) |
| __releases(dcache_inode_lock) |
| { |
| dentry->d_parent = NULL; |
| list_del(&dentry->d_u.d_child); |
| if (parent) |
| spin_unlock(&parent->d_lock); |
| dentry_iput(dentry); |
| /* |
| * dentry_iput drops the locks, at which point nobody (except |
| * transient RCU lookups) can reach this dentry. |
| */ |
| d_free(dentry); |
| return parent; |
| } |
| |
| /** |
| * d_drop - drop a dentry |
| * @dentry: dentry to drop |
| * |
| * d_drop() unhashes the entry from the parent dentry hashes, so that it won't |
| * be found through a VFS lookup any more. Note that this is different from |
| * deleting the dentry - d_delete will try to mark the dentry negative if |
| * possible, giving a successful _negative_ lookup, while d_drop will |
| * just make the cache lookup fail. |
| * |
| * d_drop() is used mainly for stuff that wants to invalidate a dentry for some |
| * reason (NFS timeouts or autofs deletes). |
| * |
| * __d_drop requires dentry->d_lock. |
| */ |
| void __d_drop(struct dentry *dentry) |
| { |
| if (!(dentry->d_flags & DCACHE_UNHASHED)) { |
| dentry->d_flags |= DCACHE_UNHASHED; |
| spin_lock(&dcache_hash_lock); |
| hlist_del_rcu(&dentry->d_hash); |
| spin_unlock(&dcache_hash_lock); |
| } |
| } |
| EXPORT_SYMBOL(__d_drop); |
| |
| void d_drop(struct dentry *dentry) |
| { |
| spin_lock(&dentry->d_lock); |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| } |
| EXPORT_SYMBOL(d_drop); |
| |
| /* |
| * 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) |
| { |
| struct dentry *parent; |
| if (!dentry) |
| return; |
| |
| repeat: |
| if (dentry->d_count == 1) |
| might_sleep(); |
| spin_lock(&dentry->d_lock); |
| BUG_ON(!dentry->d_count); |
| if (dentry->d_count > 1) { |
| dentry->d_count--; |
| spin_unlock(&dentry->d_lock); |
| return; |
| } |
| |
| if (dentry->d_op && dentry->d_op->d_delete) { |
| if (dentry->d_op->d_delete(dentry)) |
| goto kill_it; |
| } |
| |
| /* Unreachable? Get rid of it */ |
| if (d_unhashed(dentry)) |
| goto kill_it; |
| |
| /* Otherwise leave it cached and ensure it's on the LRU */ |
| dentry->d_flags |= DCACHE_REFERENCED; |
| dentry_lru_add(dentry); |
| |
| dentry->d_count--; |
| spin_unlock(&dentry->d_lock); |
| return; |
| |
| kill_it: |
| if (!spin_trylock(&dcache_inode_lock)) { |
| relock: |
| spin_unlock(&dentry->d_lock); |
| cpu_relax(); |
| goto repeat; |
| } |
| if (IS_ROOT(dentry)) |
| parent = NULL; |
| else |
| parent = dentry->d_parent; |
| if (parent && !spin_trylock(&parent->d_lock)) { |
| spin_unlock(&dcache_inode_lock); |
| goto relock; |
| } |
| dentry->d_count--; |
| /* if dentry was on the d_lru list delete it from there */ |
| dentry_lru_del(dentry); |
| /* if it was on the hash (d_delete case), then remove it */ |
| __d_drop(dentry); |
| dentry = d_kill(dentry, parent); |
| if (dentry) |
| goto repeat; |
| } |
| EXPORT_SYMBOL(dput); |
| |
| /** |
| * 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(&dentry->d_lock); |
| if (d_unhashed(dentry)) { |
| spin_unlock(&dentry->d_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(&dentry->d_lock); |
| shrink_dcache_parent(dentry); |
| spin_lock(&dentry->d_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 (dentry->d_count > 1) { |
| if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { |
| spin_unlock(&dentry->d_lock); |
| return -EBUSY; |
| } |
| } |
| |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| return 0; |
| } |
| EXPORT_SYMBOL(d_invalidate); |
| |
| /* This must be called with d_lock held */ |
| static inline struct dentry * __dget_locked_dlock(struct dentry *dentry) |
| { |
| dentry->d_count++; |
| dentry_lru_del(dentry); |
| return dentry; |
| } |
| |
| /* This must be called with d_lock held */ |
| static inline struct dentry * __dget_locked(struct dentry *dentry) |
| { |
| spin_lock(&dentry->d_lock); |
| __dget_locked_dlock(dentry); |
| spin_unlock(&dentry->d_lock); |
| return dentry; |
| } |
| |
| struct dentry * dget_locked_dlock(struct dentry *dentry) |
| { |
| return __dget_locked_dlock(dentry); |
| } |
| |
| struct dentry * dget_locked(struct dentry *dentry) |
| { |
| return __dget_locked(dentry); |
| } |
| EXPORT_SYMBOL(dget_locked); |
| |
| struct dentry *dget_parent(struct dentry *dentry) |
| { |
| struct dentry *ret; |
| |
| repeat: |
| spin_lock(&dentry->d_lock); |
| ret = dentry->d_parent; |
| if (!ret) |
| goto out; |
| if (dentry == ret) { |
| ret->d_count++; |
| goto out; |
| } |
| if (!spin_trylock(&ret->d_lock)) { |
| spin_unlock(&dentry->d_lock); |
| cpu_relax(); |
| goto repeat; |
| } |
| BUG_ON(!ret->d_count); |
| ret->d_count++; |
| spin_unlock(&ret->d_lock); |
| out: |
| spin_unlock(&dentry->d_lock); |
| return ret; |
| } |
| EXPORT_SYMBOL(dget_parent); |
| |
| /** |
| * 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 an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
| * any other hashed alias over that one unless @want_discon is set, |
| * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
| */ |
| static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
| { |
| struct dentry *alias, *discon_alias; |
| |
| again: |
| discon_alias = NULL; |
| list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
| spin_lock(&alias->d_lock); |
| if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
| if (IS_ROOT(alias) && |
| (alias->d_flags & DCACHE_DISCONNECTED)) { |
| discon_alias = alias; |
| } else if (!want_discon) { |
| __dget_locked_dlock(alias); |
| spin_unlock(&alias->d_lock); |
| return alias; |
| } |
| } |
| spin_unlock(&alias->d_lock); |
| } |
| if (discon_alias) { |
| alias = discon_alias; |
| spin_lock(&alias->d_lock); |
| if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
| if (IS_ROOT(alias) && |
| (alias->d_flags & DCACHE_DISCONNECTED)) { |
| __dget_locked_dlock(alias); |
| spin_unlock(&alias->d_lock); |
| return alias; |
| } |
| } |
| spin_unlock(&alias->d_lock); |
| goto again; |
| } |
| return NULL; |
| } |
| |
| struct dentry *d_find_alias(struct inode *inode) |
| { |
| struct dentry *de = NULL; |
| |
| if (!list_empty(&inode->i_dentry)) { |
| spin_lock(&dcache_inode_lock); |
| de = __d_find_alias(inode, 0); |
| spin_unlock(&dcache_inode_lock); |
| } |
| return de; |
| } |
| EXPORT_SYMBOL(d_find_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 dentry *dentry; |
| restart: |
| spin_lock(&dcache_inode_lock); |
| list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
| spin_lock(&dentry->d_lock); |
| if (!dentry->d_count) { |
| __dget_locked_dlock(dentry); |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_inode_lock); |
| dput(dentry); |
| goto restart; |
| } |
| spin_unlock(&dentry->d_lock); |
| } |
| spin_unlock(&dcache_inode_lock); |
| } |
| EXPORT_SYMBOL(d_prune_aliases); |
| |
| /* |
| * Throw away a dentry - free the inode, dput the parent. This requires that |
| * the LRU list has already been removed. |
| * |
| * Try to prune ancestors as well. This is necessary to prevent |
| * quadratic behavior of shrink_dcache_parent(), but is also expected |
| * to be beneficial in reducing dentry cache fragmentation. |
| */ |
| static void prune_one_dentry(struct dentry *dentry, struct dentry *parent) |
| __releases(dentry->d_lock) |
| __releases(parent->d_lock) |
| __releases(dcache_inode_lock) |
| { |
| __d_drop(dentry); |
| dentry = d_kill(dentry, parent); |
| |
| /* |
| * Prune ancestors. |
| */ |
| while (dentry) { |
| spin_lock(&dcache_inode_lock); |
| again: |
| spin_lock(&dentry->d_lock); |
| if (IS_ROOT(dentry)) |
| parent = NULL; |
| else |
| parent = dentry->d_parent; |
| if (parent && !spin_trylock(&parent->d_lock)) { |
| spin_unlock(&dentry->d_lock); |
| goto again; |
| } |
| dentry->d_count--; |
| if (dentry->d_count) { |
| if (parent) |
| spin_unlock(&parent->d_lock); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_inode_lock); |
| return; |
| } |
| |
| dentry_lru_del(dentry); |
| __d_drop(dentry); |
| dentry = d_kill(dentry, parent); |
| } |
| } |
| |
| static void shrink_dentry_list(struct list_head *list) |
| { |
| struct dentry *dentry; |
| |
| while (!list_empty(list)) { |
| struct dentry *parent; |
| |
| dentry = list_entry(list->prev, struct dentry, d_lru); |
| |
| if (!spin_trylock(&dentry->d_lock)) { |
| relock: |
| spin_unlock(&dcache_lru_lock); |
| cpu_relax(); |
| spin_lock(&dcache_lru_lock); |
| continue; |
| } |
| |
| /* |
| * We found an inuse dentry which was not removed from |
| * the LRU because of laziness during lookup. Do not free |
| * it - just keep it off the LRU list. |
| */ |
| if (dentry->d_count) { |
| __dentry_lru_del(dentry); |
| spin_unlock(&dentry->d_lock); |
| continue; |
| } |
| if (IS_ROOT(dentry)) |
| parent = NULL; |
| else |
| parent = dentry->d_parent; |
| if (parent && !spin_trylock(&parent->d_lock)) { |
| spin_unlock(&dentry->d_lock); |
| goto relock; |
| } |
| __dentry_lru_del(dentry); |
| spin_unlock(&dcache_lru_lock); |
| |
| prune_one_dentry(dentry, parent); |
| /* dcache_inode_lock and dentry->d_lock dropped */ |
| spin_lock(&dcache_inode_lock); |
| spin_lock(&dcache_lru_lock); |
| } |
| } |
| |
| /** |
| * __shrink_dcache_sb - shrink the dentry LRU on a given superblock |
| * @sb: superblock to shrink dentry LRU. |
| * @count: number of entries to prune |
| * @flags: flags to control the dentry processing |
| * |
| * If flags contains DCACHE_REFERENCED reference dentries will not be pruned. |
| */ |
| static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) |
| { |
| /* called from prune_dcache() and shrink_dcache_parent() */ |
| struct dentry *dentry; |
| LIST_HEAD(referenced); |
| LIST_HEAD(tmp); |
| int cnt = *count; |
| |
| spin_lock(&dcache_inode_lock); |
| relock: |
| spin_lock(&dcache_lru_lock); |
| while (!list_empty(&sb->s_dentry_lru)) { |
| dentry = list_entry(sb->s_dentry_lru.prev, |
| struct dentry, d_lru); |
| BUG_ON(dentry->d_sb != sb); |
| |
| if (!spin_trylock(&dentry->d_lock)) { |
| spin_unlock(&dcache_lru_lock); |
| cpu_relax(); |
| goto relock; |
| } |
| |
| /* |
| * If we are honouring the DCACHE_REFERENCED flag and the |
| * dentry has this flag set, don't free it. Clear the flag |
| * and put it back on the LRU. |
| */ |
| if (flags & DCACHE_REFERENCED && |
| dentry->d_flags & DCACHE_REFERENCED) { |
| dentry->d_flags &= ~DCACHE_REFERENCED; |
| list_move(&dentry->d_lru, &referenced); |
| spin_unlock(&dentry->d_lock); |
| } else { |
| list_move_tail(&dentry->d_lru, &tmp); |
| spin_unlock(&dentry->d_lock); |
| if (!--cnt) |
| break; |
| } |
| /* XXX: re-add cond_resched_lock when dcache_lock goes away */ |
| } |
| |
| *count = cnt; |
| shrink_dentry_list(&tmp); |
| |
| if (!list_empty(&referenced)) |
| list_splice(&referenced, &sb->s_dentry_lru); |
| spin_unlock(&dcache_lru_lock); |
| spin_unlock(&dcache_inode_lock); |
| } |
| |
| /** |
| * prune_dcache - shrink the dcache |
| * @count: number of entries to try to 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) |
| { |
| struct super_block *sb, *p = NULL; |
| int w_count; |
| int unused = dentry_stat.nr_unused; |
| int prune_ratio; |
| int pruned; |
| |
| if (unused == 0 || count == 0) |
| return; |
| if (count >= unused) |
| prune_ratio = 1; |
| else |
| prune_ratio = unused / count; |
| spin_lock(&sb_lock); |
| list_for_each_entry(sb, &super_blocks, s_list) { |
| if (list_empty(&sb->s_instances)) |
| continue; |
| if (sb->s_nr_dentry_unused == 0) |
| continue; |
| sb->s_count++; |
| /* Now, we reclaim unused dentrins with fairness. |
| * We reclaim them same percentage from each superblock. |
| * We calculate number of dentries to scan on this sb |
| * as follows, but the implementation is arranged to avoid |
| * overflows: |
| * number of dentries to scan on this sb = |
| * count * (number of dentries on this sb / |
| * number of dentries in the machine) |
| */ |
| spin_unlock(&sb_lock); |
| if (prune_ratio != 1) |
| w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1; |
| else |
| w_count = sb->s_nr_dentry_unused; |
| pruned = w_count; |
| /* |
| * We need to be sure this filesystem isn't being unmounted, |
| * otherwise we could race with generic_shutdown_super(), and |
| * end up holding a reference to an inode while the filesystem |
| * is unmounted. So we try to get s_umount, and make sure |
| * s_root isn't NULL. |
| */ |
| if (down_read_trylock(&sb->s_umount)) { |
| if ((sb->s_root != NULL) && |
| (!list_empty(&sb->s_dentry_lru))) { |
| __shrink_dcache_sb(sb, &w_count, |
| DCACHE_REFERENCED); |
| pruned -= w_count; |
| } |
| up_read(&sb->s_umount); |
| } |
| spin_lock(&sb_lock); |
| if (p) |
| __put_super(p); |
| count -= pruned; |
| p = sb; |
| /* more work left to do? */ |
| if (count <= 0) |
| break; |
| } |
| if (p) |
| __put_super(p); |
| spin_unlock(&sb_lock); |
| } |
| |
| /** |
| * 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) |
| { |
| LIST_HEAD(tmp); |
| |
| spin_lock(&dcache_inode_lock); |
| spin_lock(&dcache_lru_lock); |
| while (!list_empty(&sb->s_dentry_lru)) { |
| list_splice_init(&sb->s_dentry_lru, &tmp); |
| shrink_dentry_list(&tmp); |
| } |
| spin_unlock(&dcache_lru_lock); |
| spin_unlock(&dcache_inode_lock); |
| } |
| EXPORT_SYMBOL(shrink_dcache_sb); |
| |
| /* |
| * destroy a single subtree of dentries for unmount |
| * - see the comments on shrink_dcache_for_umount() for a description of the |
| * locking |
| */ |
| static void shrink_dcache_for_umount_subtree(struct dentry *dentry) |
| { |
| struct dentry *parent; |
| unsigned detached = 0; |
| |
| BUG_ON(!IS_ROOT(dentry)); |
| |
| /* detach this root from the system */ |
| spin_lock(&dentry->d_lock); |
| dentry_lru_del(dentry); |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| |
| for (;;) { |
| /* descend to the first leaf in the current subtree */ |
| while (!list_empty(&dentry->d_subdirs)) { |
| struct dentry *loop; |
| |
| /* this is a branch with children - detach all of them |
| * from the system in one go */ |
| spin_lock(&dentry->d_lock); |
| list_for_each_entry(loop, &dentry->d_subdirs, |
| d_u.d_child) { |
| spin_lock_nested(&loop->d_lock, |
| DENTRY_D_LOCK_NESTED); |
| dentry_lru_del(loop); |
| __d_drop(loop); |
| spin_unlock(&loop->d_lock); |
| } |
| spin_unlock(&dentry->d_lock); |
| |
| /* move to the first child */ |
| dentry = list_entry(dentry->d_subdirs.next, |
| struct dentry, d_u.d_child); |
| } |
| |
| /* consume the dentries from this leaf up through its parents |
| * until we find one with children or run out altogether */ |
| do { |
| struct inode *inode; |
| |
| if (dentry->d_count != 0) { |
| printk(KERN_ERR |
| "BUG: Dentry %p{i=%lx,n=%s}" |
| " still in use (%d)" |
| " [unmount of %s %s]\n", |
| dentry, |
| dentry->d_inode ? |
| dentry->d_inode->i_ino : 0UL, |
| dentry->d_name.name, |
| dentry->d_count, |
| dentry->d_sb->s_type->name, |
| dentry->d_sb->s_id); |
| BUG(); |
| } |
| |
| if (IS_ROOT(dentry)) { |
| parent = NULL; |
| list_del(&dentry->d_u.d_child); |
| } else { |
| parent = dentry->d_parent; |
| spin_lock(&parent->d_lock); |
| parent->d_count--; |
| list_del(&dentry->d_u.d_child); |
| spin_unlock(&parent->d_lock); |
| } |
| |
| detached++; |
| |
| inode = dentry->d_inode; |
| if (inode) { |
| dentry->d_inode = NULL; |
| list_del_init(&dentry->d_alias); |
| if (dentry->d_op && dentry->d_op->d_iput) |
| dentry->d_op->d_iput(dentry, inode); |
| else |
| iput(inode); |
| } |
| |
| d_free(dentry); |
| |
| /* finished when we fall off the top of the tree, |
| * otherwise we ascend to the parent and move to the |
| * next sibling if there is one */ |
| if (!parent) |
| return; |
| dentry = parent; |
| } while (list_empty(&dentry->d_subdirs)); |
| |
| dentry = list_entry(dentry->d_subdirs.next, |
| struct dentry, d_u.d_child); |
| } |
| } |
| |
| /* |
| * destroy the dentries attached to a superblock on unmounting |
| * - we don't need to use dentry->d_lock because: |
| * - the superblock is detached from all mountings and open files, so the |
| * dentry trees will not be rearranged by the VFS |
| * - s_umount is write-locked, so the memory pressure shrinker will ignore |
| * any dentries belonging to this superblock that it comes across |
| * - the filesystem itself is no longer permitted to rearrange the dentries |
| * in this superblock |
| */ |
| void shrink_dcache_for_umount(struct super_block *sb) |
| { |
| struct dentry *dentry; |
| |
| if (down_read_trylock(&sb->s_umount)) |
| BUG(); |
| |
| dentry = sb->s_root; |
| sb->s_root = NULL; |
| spin_lock(&dentry->d_lock); |
| dentry->d_count--; |
| spin_unlock(&dentry->d_lock); |
| shrink_dcache_for_umount_subtree(dentry); |
| |
| while (!hlist_empty(&sb->s_anon)) { |
| dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); |
| shrink_dcache_for_umount_subtree(dentry); |
| } |
| } |
| |
| /* |
| * 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; |
| struct list_head *next; |
| unsigned seq; |
| int locked = 0; |
| |
| seq = read_seqbegin(&rename_lock); |
| again: |
| this_parent = parent; |
| |
| if (d_mountpoint(parent)) |
| goto positive; |
| spin_lock(&this_parent->d_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; |
| |
| spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| /* Have we found a mount point ? */ |
| if (d_mountpoint(dentry)) { |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&this_parent->d_lock); |
| goto positive; |
| } |
| if (!list_empty(&dentry->d_subdirs)) { |
| spin_unlock(&this_parent->d_lock); |
| spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
| this_parent = dentry; |
| spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
| goto repeat; |
| } |
| spin_unlock(&dentry->d_lock); |
| } |
| /* |
| * All done at this level ... ascend and resume the search. |
| */ |
| if (this_parent != parent) { |
| struct dentry *tmp; |
| struct dentry *child; |
| |
| tmp = this_parent->d_parent; |
| rcu_read_lock(); |
| spin_unlock(&this_parent->d_lock); |
| child = this_parent; |
| this_parent = tmp; |
| spin_lock(&this_parent->d_lock); |
| /* might go back up the wrong parent if we have had a rename |
| * or deletion */ |
| if (this_parent != child->d_parent || |
| (!locked && read_seqretry(&rename_lock, seq))) { |
| spin_unlock(&this_parent->d_lock); |
| rcu_read_unlock(); |
| goto rename_retry; |
| } |
| rcu_read_unlock(); |
| next = child->d_u.d_child.next; |
| goto resume; |
| } |
| spin_unlock(&this_parent->d_lock); |
| if (!locked && read_seqretry(&rename_lock, seq)) |
| goto rename_retry; |
| if (locked) |
| write_sequnlock(&rename_lock); |
| return 0; /* No mount points found in tree */ |
| positive: |
| if (!locked && read_seqretry(&rename_lock, seq)) |
| goto rename_retry; |
| if (locked) |
| write_sequnlock(&rename_lock); |
| return 1; |
| |
| rename_retry: |
| locked = 1; |
| write_seqlock(&rename_lock); |
| goto again; |
| } |
| EXPORT_SYMBOL(have_submounts); |
| |
| /* |
| * 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; |
| struct list_head *next; |
| unsigned seq; |
| int found = 0; |
| int locked = 0; |
| |
| seq = read_seqbegin(&rename_lock); |
| again: |
| this_parent = parent; |
| spin_lock(&this_parent->d_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; |
| |
| spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| |
| /* |
| * move only zero ref count dentries to the end |
| * of the unused list for prune_dcache |
| */ |
| if (!dentry->d_count) { |
| dentry_lru_move_tail(dentry); |
| found++; |
| } else { |
| dentry_lru_del(dentry); |
| } |
| |
| /* |
| * 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()) { |
| spin_unlock(&dentry->d_lock); |
| goto out; |
| } |
| |
| /* |
| * Descend a level if the d_subdirs list is non-empty. |
| */ |
| if (!list_empty(&dentry->d_subdirs)) { |
| spin_unlock(&this_parent->d_lock); |
| spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
| this_parent = dentry; |
| spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
| goto repeat; |
| } |
| |
| spin_unlock(&dentry->d_lock); |
| } |
| /* |
| * All done at this level ... ascend and resume the search. |
| */ |
| if (this_parent != parent) { |
| struct dentry *tmp; |
| struct dentry *child; |
| |
| tmp = this_parent->d_parent; |
| rcu_read_lock(); |
| spin_unlock(&this_parent->d_lock); |
| child = this_parent; |
| this_parent = tmp; |
| spin_lock(&this_parent->d_lock); |
| /* might go back up the wrong parent if we have had a rename |
| * or deletion */ |
| if (this_parent != child->d_parent || |
| (!locked && read_seqretry(&rename_lock, seq))) { |
| spin_unlock(&this_parent->d_lock); |
| rcu_read_unlock(); |
| goto rename_retry; |
| } |
| rcu_read_unlock(); |
| next = child->d_u.d_child.next; |
| goto resume; |
| } |
| out: |
| spin_unlock(&this_parent->d_lock); |
| if (!locked && read_seqretry(&rename_lock, seq)) |
| goto rename_retry; |
| if (locked) |
| write_sequnlock(&rename_lock); |
| return found; |
| |
| rename_retry: |
| if (found) |
| return found; |
| locked = 1; |
| write_seqlock(&rename_lock); |
| goto again; |
| } |
| |
| /** |
| * 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) |
| { |
| struct super_block *sb = parent->d_sb; |
| int found; |
| |
| while ((found = select_parent(parent)) != 0) |
| __shrink_dcache_sb(sb, &found, 0); |
| } |
| EXPORT_SYMBOL(shrink_dcache_parent); |
| |
| /* |
| * 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(struct shrinker *shrink, 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; |
| } |
| |
| static struct shrinker dcache_shrinker = { |
| .shrink = shrink_dcache_memory, |
| .seeks = DEFAULT_SEEKS, |
| }; |
| |
| /** |
| * 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; |
| |
| 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; |
| INIT_HLIST_NODE(&dentry->d_hash); |
| INIT_LIST_HEAD(&dentry->d_lru); |
| INIT_LIST_HEAD(&dentry->d_subdirs); |
| INIT_LIST_HEAD(&dentry->d_alias); |
| INIT_LIST_HEAD(&dentry->d_u.d_child); |
| |
| if (parent) { |
| spin_lock(&parent->d_lock); |
| spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| dentry->d_parent = dget_dlock(parent); |
| dentry->d_sb = parent->d_sb; |
| list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&parent->d_lock); |
| } |
| |
| this_cpu_inc(nr_dentry); |
| |
| return dentry; |
| } |
| EXPORT_SYMBOL(d_alloc); |
| |
| 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); |
| } |
| EXPORT_SYMBOL(d_alloc_name); |
| |
| static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
| { |
| spin_lock(&dentry->d_lock); |
| if (inode) |
| list_add(&dentry->d_alias, &inode->i_dentry); |
| dentry->d_inode = inode; |
| spin_unlock(&dentry->d_lock); |
| fsnotify_d_instantiate(dentry, inode); |
| } |
| |
| /** |
| * 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_inode_lock); |
| __d_instantiate(entry, inode); |
| spin_unlock(&dcache_inode_lock); |
| security_d_instantiate(entry, inode); |
| } |
| EXPORT_SYMBOL(d_instantiate); |
| |
| /** |
| * 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. |
| */ |
| static 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; |
| |
| if (!inode) { |
| __d_instantiate(entry, NULL); |
| return NULL; |
| } |
| |
| list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
| struct qstr *qstr = &alias->d_name; |
| |
| /* |
| * Don't need alias->d_lock here, because aliases with |
| * d_parent == entry->d_parent are not subject to name or |
| * parent changes, because the parent inode i_mutex is held. |
| */ |
| 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); |
| return alias; |
| } |
| |
| __d_instantiate(entry, inode); |
| return NULL; |
| } |
| |
| struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
| { |
| struct dentry *result; |
| |
| BUG_ON(!list_empty(&entry->d_alias)); |
| |
| spin_lock(&dcache_inode_lock); |
| result = __d_instantiate_unique(entry, inode); |
| spin_unlock(&dcache_inode_lock); |
| |
| if (!result) { |
| security_d_instantiate(entry, inode); |
| return NULL; |
| } |
| |
| BUG_ON(!d_unhashed(result)); |
| iput(inode); |
| return result; |
| } |
| |
| 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; |
| } |
| EXPORT_SYMBOL(d_alloc_root); |
| |
| 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_obtain_alias - find or allocate a dentry for a given inode |
| * @inode: inode to allocate the dentry for |
| * |
| * Obtain a dentry for an inode resulting from NFS filehandle conversion or |
| * similar open by handle operations. The returned dentry may be anonymous, |
| * or may have a full name (if the inode was already in the cache). |
| * |
| * 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. In case of an error the reference on the inode is released. |
| * To make it easier to use in export operations a %NULL or IS_ERR inode may |
| * be passed in and will be the error will be propagate to the return value, |
| * with a %NULL @inode replaced by ERR_PTR(-ESTALE). |
| */ |
| struct dentry *d_obtain_alias(struct inode *inode) |
| { |
| static const struct qstr anonstring = { .name = "" }; |
| struct dentry *tmp; |
| struct dentry *res; |
| |
| if (!inode) |
| return ERR_PTR(-ESTALE); |
| if (IS_ERR(inode)) |
| return ERR_CAST(inode); |
| |
| res = d_find_alias(inode); |
| if (res) |
| goto out_iput; |
| |
| tmp = d_alloc(NULL, &anonstring); |
| if (!tmp) { |
| res = ERR_PTR(-ENOMEM); |
| goto out_iput; |
| } |
| tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
| |
| |
| spin_lock(&dcache_inode_lock); |
| res = __d_find_alias(inode, 0); |
| if (res) { |
| spin_unlock(&dcache_inode_lock); |
| dput(tmp); |
| goto out_iput; |
| } |
| |
| /* attach a disconnected dentry */ |
| spin_lock(&tmp->d_lock); |
| tmp->d_sb = inode->i_sb; |
| tmp->d_inode = inode; |
| tmp->d_flags |= DCACHE_DISCONNECTED; |
| tmp->d_flags &= ~DCACHE_UNHASHED; |
| list_add(&tmp->d_alias, &inode->i_dentry); |
| spin_lock(&dcache_hash_lock); |
| hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon); |
| spin_unlock(&dcache_hash_lock); |
| spin_unlock(&tmp->d_lock); |
| spin_unlock(&dcache_inode_lock); |
| |
| return tmp; |
| |
| out_iput: |
| iput(inode); |
| return res; |
| } |
| EXPORT_SYMBOL(d_obtain_alias); |
| |
| /** |
| * 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 && S_ISDIR(inode->i_mode)) { |
| spin_lock(&dcache_inode_lock); |
| new = __d_find_alias(inode, 1); |
| if (new) { |
| BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
| spin_unlock(&dcache_inode_lock); |
| security_d_instantiate(new, inode); |
| d_move(new, dentry); |
| iput(inode); |
| } else { |
| /* already taking dcache_inode_lock, so d_add() by hand */ |
| __d_instantiate(dentry, inode); |
| spin_unlock(&dcache_inode_lock); |
| security_d_instantiate(dentry, inode); |
| d_rehash(dentry); |
| } |
| } else |
| d_add(dentry, inode); |
| return new; |
| } |
| EXPORT_SYMBOL(d_splice_alias); |
| |
| /** |
| * d_add_ci - lookup or allocate new dentry with case-exact name |
| * @inode: the inode case-insensitive lookup has found |
| * @dentry: the negative dentry that was passed to the parent's lookup func |
| * @name: the case-exact name to be associated with the returned dentry |
| * |
| * This is to avoid filling the dcache with case-insensitive names to the |
| * same inode, only the actual correct case is stored in the dcache for |
| * case-insensitive filesystems. |
| * |
| * For a case-insensitive lookup match and if the the case-exact dentry |
| * already exists in in the dcache, use it and return it. |
| * |
| * If no entry exists with the exact case name, allocate new dentry with |
| * the exact case, and return the spliced entry. |
| */ |
| struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
| struct qstr *name) |
| { |
| int error; |
| struct dentry *found; |
| struct dentry *new; |
| |
| /* |
| * First check if a dentry matching the name already exists, |
| * if not go ahead and create it now. |
| */ |
| found = d_hash_and_lookup(dentry->d_parent, name); |
| if (!found) { |
| new = d_alloc(dentry->d_parent, name); |
| if (!new) { |
| error = -ENOMEM; |
| goto err_out; |
| } |
| |
| found = d_splice_alias(inode, new); |
| if (found) { |
| dput(new); |
| return found; |
| } |
| return new; |
| } |
| |
| /* |
| * If a matching dentry exists, and it's not negative use it. |
| * |
| * Decrement the reference count to balance the iget() done |
| * earlier on. |
| */ |
| if (found->d_inode) { |
| if (unlikely(found->d_inode != inode)) { |
| /* This can't happen because bad inodes are unhashed. */ |
| BUG_ON(!is_bad_inode(inode)); |
| BUG_ON(!is_bad_inode(found->d_inode)); |
| } |
| iput(inode); |
| return found; |
| } |
| |
| /* |
| * Negative dentry: instantiate it unless the inode is a directory and |
| * already has a dentry. |
| */ |
| spin_lock(&dcache_inode_lock); |
| if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) { |
| __d_instantiate(found, inode); |
| spin_unlock(&dcache_inode_lock); |
| security_d_instantiate(found, inode); |
| return found; |
| } |
| |
| /* |
| * In case a directory already has a (disconnected) entry grab a |
| * reference to it, move it in place and use it. |
| */ |
| new = list_entry(inode->i_dentry.next, struct dentry, d_alias); |
| dget_locked(new); |
| spin_unlock(&dcache_inode_lock); |
| security_d_instantiate(found, inode); |
| d_move(new, found); |
| iput(inode); |
| dput(found); |
| return new; |
| |
| err_out: |
| iput(inode); |
| return ERR_PTR(error); |
| } |
| EXPORT_SYMBOL(d_add_ci); |
| |
| /** |
| * d_lookup - search for a dentry |
| * @parent: parent dentry |
| * @name: qstr of name we wish to find |
| * Returns: dentry, or NULL |
| * |
| * d_lookup 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 dput to free the entry when it has |
| * finished using it. %NULL is returned if the dentry does not exist. |
| */ |
| struct dentry * d_lookup(struct dentry * parent, struct qstr * name) |
| { |
| struct dentry * dentry = NULL; |
| unsigned seq; |
| |
| do { |
| seq = read_seqbegin(&rename_lock); |
| dentry = __d_lookup(parent, name); |
| if (dentry) |
| break; |
| } while (read_seqretry(&rename_lock, seq)); |
| return dentry; |
| } |
| EXPORT_SYMBOL(d_lookup); |
| |
| /* |
| * __d_lookup - search for a dentry (racy) |
| * @parent: parent dentry |
| * @name: qstr of name we wish to find |
| * Returns: dentry, or NULL |
| * |
| * __d_lookup is like d_lookup, however it may (rarely) return a |
| * false-negative result due to unrelated rename activity. |
| * |
| * __d_lookup is slightly faster by avoiding rename_lock read seqlock, |
| * however it must be used carefully, eg. with a following d_lookup in |
| * the case of failure. |
| * |
| * __d_lookup callers must be commented. |
| */ |
| 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; |
| |
| /* |
| * The hash list is protected using RCU. |
| * |
| * Take d_lock when comparing a candidate dentry, to avoid races |
| * with d_move(). |
| * |
| * It is possible that concurrent renames can mess up our list |
| * walk here and result in missing our dentry, resulting in the |
| * false-negative result. d_lookup() protects against concurrent |
| * renames using rename_lock seqlock. |
| * |
| * See Documentation/vfs/dcache-locking.txt for more details. |
| */ |
| 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; |
| |
| /* non-existing due to RCU? */ |
| if (d_unhashed(dentry)) |
| 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, parent->d_inode, |
| dentry, dentry->d_inode, |
| qstr->len, qstr->name, name)) |
| goto next; |
| } else { |
| if (qstr->len != len) |
| goto next; |
| if (memcmp(qstr->name, str, len)) |
| goto next; |
| } |
| |
| dentry->d_count++; |
| found = dentry; |
| spin_unlock(&dentry->d_lock); |
| break; |
| next: |
| spin_unlock(&dentry->d_lock); |
| } |
| rcu_read_unlock(); |
| |
| return found; |
| } |
| |
| /** |
| * d_hash_and_lookup - hash the qstr then search for a dentry |
| * @dir: Directory to search in |
| * @name: qstr of name we wish to find |
| * |
| * On hash failure or on lookup failure NULL is returned. |
| */ |
| struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
| { |
| struct dentry *dentry = NULL; |
| |
| /* |
| * 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, dir->d_inode, name) < 0) |
| goto out; |
| } |
| dentry = d_lookup(dir, name); |
| out: |
| return dentry; |
| } |
| |
| /** |
| * d_validate - verify dentry provided from insecure source (deprecated) |
| * @dentry: The dentry alleged to be valid child of @dparent |
| * @dparent: The parent dentry (known to be valid) |
| * |
| * 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. |
| * |
| * This function is slow for big directories, and deprecated, do not use it. |
| */ |
| int d_validate(struct dentry *dentry, struct dentry *dparent) |
| { |
| struct dentry *child; |
| |
| spin_lock(&dparent->d_lock); |
| list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
| if (dentry == child) { |
| spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| __dget_locked_dlock(dentry); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dparent->d_lock); |
| return 1; |
| } |
| } |
| spin_unlock(&dparent->d_lock); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(d_validate); |
| |
| /* |
| * 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_inode_lock); |
| spin_lock(&dentry->d_lock); |
| isdir = S_ISDIR(dentry->d_inode->i_mode); |
| if (dentry->d_count == 1) { |
| dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
| dentry_iput(dentry); |
| fsnotify_nameremove(dentry, isdir); |
| return; |
| } |
| |
| if (!d_unhashed(dentry)) |
| __d_drop(dentry); |
| |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_inode_lock); |
| |
| fsnotify_nameremove(dentry, isdir); |
| } |
| EXPORT_SYMBOL(d_delete); |
| |
| static void __d_rehash(struct dentry * entry, struct hlist_head *list) |
| { |
| |
| entry->d_flags &= ~DCACHE_UNHASHED; |
| hlist_add_head_rcu(&entry->d_hash, list); |
| } |
| |
| static void _d_rehash(struct dentry * entry) |
| { |
| __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
| } |
| |
| /** |
| * 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) |
| { |
| spin_lock(&entry->d_lock); |
| spin_lock(&dcache_hash_lock); |
| _d_rehash(entry); |
| spin_unlock(&dcache_hash_lock); |
| spin_unlock(&entry->d_lock); |
| } |
| EXPORT_SYMBOL(d_rehash); |
| |
| /** |
| * dentry_update_name_case - update case insensitive dentry with a new name |
| * @dentry: dentry to be updated |
| * @name: new name |
| * |
| * Update a case insensitive dentry with new case of name. |
| * |
| * dentry must have been returned by d_lookup with name @name. Old and new |
| * name lengths must match (ie. no d_compare which allows mismatched name |
| * lengths). |
| * |
| * Parent inode i_mutex must be held over d_lookup and into this call (to |
| * keep renames and concurrent inserts, and readdir(2) away). |
| */ |
| void dentry_update_name_case(struct dentry *dentry, struct qstr *name) |
| { |
| BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); |
| BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
| |
| spin_lock(&dentry->d_lock); |
| memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
| spin_unlock(&dentry->d_lock); |
| } |
| EXPORT_SYMBOL(dentry_update_name_case); |
| |
| static void switch_names(struct dentry *dentry, struct dentry *target) |
| { |
| if (dname_external(target)) { |
| if (dname_external(dentry)) { |
| /* |
| * Both external: swap the pointers |
| */ |
| swap(target->d_name.name, dentry->d_name.name); |
| } else { |
| /* |
| * dentry:internal, target:external. Steal target's |
| * storage and make target internal. |
| */ |
| memcpy(target->d_iname, dentry->d_name.name, |
| dentry->d_name.len + 1); |
| 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); |
| dentry->d_name.len = target->d_name.len; |
| return; |
| } |
| } |
| swap(dentry->d_name.len, target->d_name.len); |
| } |
| |
| 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_parents_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); |
| } |
| |
| /* |
| * 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.. |
| */ |
| /* |
| * 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"); |
| |
| BUG_ON(d_ancestor(dentry, target)); |
| BUG_ON(d_ancestor(target, dentry)); |
| |
| write_seqlock(&rename_lock); |
| |
| dentry_lock_for_move(dentry, target); |
| |
| /* Move the dentry to the target hash queue, if on different bucket */ |
| spin_lock(&dcache_hash_lock); |
| if (!d_unhashed(dentry)) |
| hlist_del_rcu(&dentry->d_hash); |
| __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
| spin_unlock(&dcache_hash_lock); |
| |
| /* 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); |
| swap(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 { |
| swap(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); |
| |
| dentry_unlock_parents_for_move(dentry, target); |
| spin_unlock(&target->d_lock); |
| fsnotify_d_move(dentry); |
| spin_unlock(&dentry->d_lock); |
| write_sequnlock(&rename_lock); |
| } |
| EXPORT_SYMBOL(d_move); |
| |
| /** |
| * d_ancestor - search for an ancestor |
| * @p1: ancestor dentry |
| * @p2: child dentry |
| * |
| * Returns the ancestor dentry of p2 which is a child of p1, if p1 is |
| * an ancestor of p2, else NULL. |
| */ |
| struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
| { |
| struct dentry *p; |
| |
| for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
| if (p->d_parent == p1) |
| return p; |
| } |
| return NULL; |
| } |
| |
| /* |
| * This helper attempts to cope with remotely renamed directories |
| * |
| * It assumes that the caller is already holding |
| * dentry->d_parent->d_inode->i_mutex and the dcache_inode_lock |
| * |
| * Note: If ever the locking in lock_rename() changes, then please |
| * remember to update this too... |
| */ |
| static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) |
| __releases(dcache_inode_lock) |
| { |
| struct mutex *m1 = NULL, *m2 = NULL; |
| struct dentry *ret; |
| |
| /* If alias and dentry share a parent, then no extra locks required */ |
| if (alias->d_parent == dentry->d_parent) |
| goto out_unalias; |
| |
| /* Check for loops */ |
| ret = ERR_PTR(-ELOOP); |
| if (d_ancestor(alias, dentry)) |
| goto out_err; |
| |
| /* See lock_rename() */ |
| ret = ERR_PTR(-EBUSY); |
| if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
| goto out_err; |
| m1 = &dentry->d_sb->s_vfs_rename_mutex; |
| if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
| goto out_err; |
| m2 = &alias->d_parent->d_inode->i_mutex; |
| out_unalias: |
| d_move(alias, dentry); |
| ret = alias; |
| out_err: |
| spin_unlock(&dcache_inode_lock); |
| if (m2) |
| mutex_unlock(m2); |
| if (m1) |
| mutex_unlock(m1); |
| return ret; |
| } |
| |
| /* |
| * Prepare an anonymous dentry for life in the superblock's dentry tree as a |
| * named dentry in place of the dentry to be replaced. |
| * returns with anon->d_lock held! |
| */ |
| static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) |
| { |
| struct dentry *dparent, *aparent; |
| |
| dentry_lock_for_move(anon, dentry); |
| |
| dparent = dentry->d_parent; |
| aparent = anon->d_parent; |
| |
| switch_names(dentry, anon); |
| swap(dentry->d_name.hash, anon->d_name.hash); |
| |
| dentry->d_parent = (aparent == anon) ? dentry : aparent; |
| list_del(&dentry->d_u.d_child); |
| if (!IS_ROOT(dentry)) |
| list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
| else |
| INIT_LIST_HEAD(&dentry->d_u.d_child); |
| |
| anon->d_parent = (dparent == dentry) ? anon : dparent; |
| list_del(&anon->d_u.d_child); |
| if (!IS_ROOT(anon)) |
| list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); |
| else |
| INIT_LIST_HEAD(&anon->d_u.d_child); |
| |
| dentry_unlock_parents_for_move(anon, dentry); |
| spin_unlock(&dentry->d_lock); |
| |
| /* anon->d_lock still locked, returns locked */ |
| anon->d_flags &= ~DCACHE_DISCONNECTED; |
| } |
| |
| /** |
| * d_materialise_unique - introduce an inode into the tree |
| * @dentry: candidate dentry |
| * @inode: inode to bind to the dentry, to which aliases may be attached |
| * |
| * Introduces an dentry into the tree, substituting an extant disconnected |
| * root directory alias in its place if there is one |
| */ |
| struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) |
| { |
| struct dentry *actual; |
| |
| BUG_ON(!d_unhashed(dentry)); |
| |
| spin_lock(&dcache_inode_lock); |
| |
| if (!inode) { |
| actual = dentry; |
| __d_instantiate(dentry, NULL); |
| goto found_lock; |
| } |
| |
| if (S_ISDIR(inode->i_mode)) { |
| struct dentry *alias; |
| |
| /* Does an aliased dentry already exist? */ |
| alias = __d_find_alias(inode, 0); |
| if (alias) { |
| actual = alias; |
| /* Is this an anonymous mountpoint that we could splice |
| * into our tree? */ |
| if (IS_ROOT(alias)) { |
| __d_materialise_dentry(dentry, alias); |
| __d_drop(alias); |
| goto found; |
| } |
| /* Nope, but we must(!) avoid directory aliasing */ |
| actual = __d_unalias(dentry, alias); |
| if (IS_ERR(actual)) |
| dput(alias); |
| goto out_nolock; |
| } |
| } |
| |
| /* Add a unique reference */ |
| actual = __d_instantiate_unique(dentry, inode); |
| if (!actual) |
| actual = dentry; |
| else if (unlikely(!d_unhashed(actual))) |
| goto shouldnt_be_hashed; |
| |
| found_lock: |
| spin_lock(&actual->d_lock); |
| found: |
| spin_lock(&dcache_hash_lock); |
| _d_rehash(actual); |
| spin_unlock(&dcache_hash_lock); |
| spin_unlock(&actual->d_lock); |
| spin_unlock(&dcache_inode_lock); |
| out_nolock: |
| if (actual == dentry) { |
| security_d_instantiate(dentry, inode); |
| return NULL; |
| } |
| |
| iput(inode); |
| return actual; |
| |
| shouldnt_be_hashed: |
| spin_unlock(&dcache_inode_lock); |
| BUG(); |
| } |
| EXPORT_SYMBOL_GPL(d_materialise_unique); |
| |
| 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; |
| } |
| |
| static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
| { |
| return prepend(buffer, buflen, name->name, name->len); |
| } |
| |
| /** |
| * Prepend path string to a buffer |
| * |
| * @path: the dentry/vfsmount to report |
| * @root: root vfsmnt/dentry (may be modified by this function) |
| * @buffer: pointer to the end of the buffer |
| * @buflen: pointer to buffer length |
| * |
| * Caller holds the rename_lock. |
| * |
| * If path is not reachable from the supplied root, then the value of |
| * root is changed (without modifying refcounts). |
| */ |
| static int prepend_path(const struct path *path, struct path *root, |
| char **buffer, int *buflen) |
| { |
| struct dentry *dentry = path->dentry; |
| struct vfsmount *vfsmnt = path->mnt; |
| bool slash = false; |
| int error = 0; |
| |
| br_read_lock(vfsmount_lock); |
| while (dentry != root->dentry || vfsmnt != root->mnt) { |
| struct dentry * parent; |
| |
| 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; |
| prefetch(parent); |
| spin_lock(&dentry->d_lock); |
| error = prepend_name(buffer, buflen, &dentry->d_name); |
| spin_unlock(&dentry->d_lock); |
| if (!error) |
| error = prepend(buffer, buflen, "/", 1); |
| if (error) |
| break; |
| |
| slash = true; |
| dentry = parent; |
| } |
| |
| out: |
| if (!error && !slash) |
| error = prepend(buffer, buflen, "/", 1); |
| |
| br_read_unlock(vfsmount_lock); |
| return error; |
| |
| global_root: |
| /* |
| * Filesystems needing to implement special "root names" |
| * should do so with ->d_dname() |
| */ |
| if (IS_ROOT(dentry) && |
| (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { |
| WARN(1, "Root dentry has weird name <%.*s>\n", |
| (int) dentry->d_name.len, dentry->d_name.name); |
| } |
| root->mnt = vfsmnt; |
| root->dentry = dentry; |
| goto out; |
| } |
| |
| /** |
| * __d_path - return the path of a dentry |
| * @path: the dentry/vfsmount to report |
| * @root: root vfsmnt/dentry (may be modified by this function) |
| * @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 path is not reachable from the supplied root, then the value of |
| * root is changed (without modifying refcounts). |
| */ |
| char *__d_path(const struct path *path, struct path *root, |
| char *buf, int buflen) |
| { |
| char *res = buf + buflen; |
| int error; |
| |
| prepend(&res, &buflen, "\0", 1); |
| write_seqlock(&rename_lock); |
| error = prepend_path(path, root, &res, &buflen); |
| write_sequnlock(&rename_lock); |
| |
| if (error) |
| 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, 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); |
| } |
| |
| /** |
| * 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; |
| struct path tmp; |
| 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: |
| */ |
| if (path->dentry->d_op && path->dentry->d_op->d_dname) |
| return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
| |
| get_fs_root(current->fs, &root); |
| write_seqlock(&rename_lock); |
| tmp = root; |
| error = path_with_deleted(path, &tmp, &res, &buflen); |
| if (error) |
| res = ERR_PTR(error); |
| write_sequnlock(&rename_lock); |
| path_put(&root); |
| return res; |
| } |
| EXPORT_SYMBOL(d_path); |
| |
| /** |
| * d_path_with_unreachable - return the path of a dentry |
| * @path: path to report |
| * @buf: buffer to return value in |
| * @buflen: buffer length |
| * |
| * The difference from d_path() is that this prepends "(unreachable)" |
| * to paths which are unreachable from the current process' root. |
| */ |
| char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) |
| { |
| char *res = buf + buflen; |
| struct path root; |
| struct path tmp; |
| int error; |
| |
| if (path->dentry->d_op && path->dentry->d_op->d_dname) |
| return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
| |
| get_fs_root(current->fs, &root); |
| write_seqlock(&rename_lock); |
| tmp = root; |
| error = path_with_deleted(path, &tmp, &res, &buflen); |
| if (!error && !path_equal(&tmp, &root)) |
| error = prepend_unreachable(&res, &buflen); |
| write_sequnlock(&rename_lock); |
| path_put(&root); |
| if (error) |
| res = ERR_PTR(error); |
| |
| return res; |
| } |
| |
| /* |
| * 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); |
| } |
| |
| /* |
| * Write full pathname from the root of the filesystem into the buffer. |
| */ |
| static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
| { |
| char *end = buf + buflen; |
| char *retval; |
| |
| prepend(&end, &buflen, "\0", 1); |
| if (buflen < 1) |
| goto Elong; |
| /* Get '/' right */ |
| retval = end-1; |
| *retval = '/'; |
| |
| while (!IS_ROOT(dentry)) { |
| struct dentry *parent = dentry->d_parent; |
| int error; |
| |
| prefetch(parent); |
| spin_lock(&dentry->d_lock); |
| error = prepend_name(&end, &buflen, &dentry->d_name); |
| spin_unlock(&dentry->d_lock); |
| if (error != 0 || prepend(&end, &buflen, "/", 1) != 0) |
| goto Elong; |
| |
| retval = end; |
| dentry = parent; |
| } |
| return retval; |
| Elong: |
| return ERR_PTR(-ENAMETOOLONG); |
| } |
| |
| char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) |
| { |
| char *retval; |
| |
| write_seqlock(&rename_lock); |
| retval = __dentry_path(dentry, buf, buflen); |
| write_sequnlock(&rename_lock); |
| |
| return retval; |
| } |
| EXPORT_SYMBOL(dentry_path_raw); |
| |
| char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
| { |
| char *p = NULL; |
| char *retval; |
| |
| write_seqlock(&rename_lock); |
| if (d_unlinked(dentry)) { |
| p = buf + buflen; |
| if (prepend(&p, &buflen, "//deleted", 10) != 0) |
| goto Elong; |
| buflen++; |
| } |
| retval = __dentry_path(dentry, buf, buflen); |
| write_sequnlock(&rename_lock); |
| if (!IS_ERR(retval) && p) |
| *p = '/'; /* restore '/' overriden with '\0' */ |
| return retval; |
| Elong: |
| return ERR_PTR(-ENAMETOOLONG); |
| } |
| |
| /* |
| * 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 = (char *) __get_free_page(GFP_USER); |
| |
| if (!page) |
| return -ENOMEM; |
| |
| get_fs_root_and_pwd(current->fs, &root, &pwd); |
| |
| error = -ENOENT; |
| write_seqlock(&rename_lock); |
| if (!d_unlinked(pwd.dentry)) { |
| unsigned long len; |
| struct path tmp = root; |
| char *cwd = page + PAGE_SIZE; |
| int buflen = PAGE_SIZE; |
| |
| prepend(&cwd, &buflen, "\0", 1); |
| error = prepend_path(&pwd, &tmp, &cwd, &buflen); |
| write_sequnlock(&rename_lock); |
| |
| if (error) |
| goto out; |
| |
| /* Unreachable from current root */ |
| if (!path_equal(&tmp, &root)) { |
| error = prepend_unreachable(&cwd, &buflen); |
| if (error) |
| goto out; |
| } |
| |
| error = -ERANGE; |
| len = PAGE_SIZE + page - cwd; |
| if (len <= size) { |
| error = len; |
| if (copy_to_user(buf, cwd, len)) |
| error = -EFAULT; |
| } |
| } else { |
| write_sequnlock(&rename_lock); |
| } |
| |
| out: |
| path_put(&pwd); |
| path_put(&root); |
| 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; |
| unsigned seq; |
| |
| if (new_dentry == old_dentry) |
| return 1; |
| |
| do { |
| /* for restarting inner loop in case of seq retry */ |
| seq = read_seqbegin(&rename_lock); |
| /* |
| * Need rcu_readlock to protect against the d_parent trashing |
| * due to d_move |
| */ |
| rcu_read_lock(); |
| if (d_ancestor(old_dentry, new_dentry)) |
| result = 1; |
| else |
| result = 0; |
| rcu_read_unlock(); |
| } while (read_seqretry(&rename_lock, seq)); |
| |
| return result; |
| } |
| |
| int path_is_under(struct path *path1, struct path *path2) |
| { |
| struct vfsmount *mnt = path1->mnt; |
| struct dentry *dentry = path1->dentry; |
| int res; |
| |
| br_read_lock(vfsmount_lock); |
| if (mnt != path2->mnt) { |
| for (;;) { |
| if (mnt->mnt_parent == mnt) { |
| br_read_unlock(vfsmount_lock); |
| return 0; |
| } |
| if (mnt->mnt_parent == path2->mnt) |
| break; |
| mnt = mnt->mnt_parent; |
| } |
| dentry = mnt->mnt_mountpoint; |
| } |
| res = is_subdir(dentry, path2->dentry); |
| br_read_unlock(vfsmount_lock); |
| return res; |
| } |
| EXPORT_SYMBOL(path_is_under); |
| |
| void d_genocide(struct dentry *root) |
| { |
| struct dentry *this_parent; |
| struct list_head *next; |
| unsigned seq; |
| int locked = 0; |
| |
| seq = read_seqbegin(&rename_lock); |
| again: |
| this_parent = root; |
| spin_lock(&this_parent->d_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; |
| |
| spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| if (d_unhashed(dentry) || !dentry->d_inode) { |
| spin_unlock(&dentry->d_lock); |
| continue; |
| } |
| if (!list_empty(&dentry->d_subdirs)) { |
| spin_unlock(&this_parent->d_lock); |
| spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
| this_parent = dentry; |
| spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
| goto repeat; |
| } |
| if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
| dentry->d_flags |= DCACHE_GENOCIDE; |
| dentry->d_count--; |
| } |
| spin_unlock(&dentry->d_lock); |
| } |
| if (this_parent != root) { |
| struct dentry *tmp; |
| struct dentry *child; |
| |
| tmp = this_parent->d_parent; |
| if (!(this_parent->d_flags & DCACHE_GENOCIDE)) { |
| this_parent->d_flags |= DCACHE_GENOCIDE; |
| this_parent->d_count--; |
| } |
| rcu_read_lock(); |
| spin_unlock(&this_parent->d_lock); |
| child = this_parent; |
| this_parent = tmp; |
| spin_lock(&this_parent->d_lock); |
| /* might go back up the wrong parent if we have had a rename |
| * or deletion */ |
| if (this_parent != child->d_parent || |
| (!locked && read_seqretry(&rename_lock, seq))) { |
| spin_unlock(&this_parent->d_lock); |
| rcu_read_unlock(); |
| goto rename_retry; |
| } |
| rcu_read_unlock(); |
| next = child->d_u.d_child.next; |
| goto resume; |
| } |
| spin_unlock(&this_parent->d_lock); |
| if (!locked && read_seqretry(&rename_lock, seq)) |
| goto rename_retry; |
| if (locked) |
| write_sequnlock(&rename_lock); |
| return; |
| |
| rename_retry: |
| locked = 1; |
| write_seqlock(&rename_lock); |
| goto again; |
| } |
| |
| /** |
| * 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; |
| |
| dentry = d_hash_and_lookup(dir, name); |
| if (dentry) { |
| if (dentry->d_inode) |
| ino = dentry->d_inode->i_ino; |
| dput(dentry); |
| } |
| return ino; |
| } |
| EXPORT_SYMBOL(find_inode_number); |
| |
| 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(void) |
| { |
| 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(dentry, |
| SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
| |
| register_shrinker(&dcache_shrinker); |
| |
| /* 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 */ |
| struct kmem_cache *names_cachep __read_mostly; |
| EXPORT_SYMBOL(names_cachep); |
| |
| EXPORT_SYMBOL(d_genocide); |
| |
| 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); |
| |
| dcache_init(); |
| inode_init(); |
| files_init(mempages); |
| mnt_init(); |
| bdev_cache_init(); |
| chrdev_init(); |
| } |