/* * 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/malloc.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/smp_lock.h> #include <linux/cache.h> #include <asm/uaccess.h> #define DCACHE_PARANOIA 1 /* #define DCACHE_DEBUG 1 */ spinlock_t dcache_lock = SPIN_LOCK_UNLOCKED; /* Right now the dcache depends on the kernel lock */ #define check_lock() if (!kernel_locked()) BUG() 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); struct { int nr_dentry; int nr_unused; int age_limit; /* age in seconds */ int want_pages; /* pages requested by system */ int dummy[2]; } dentry_stat = {0, 0, 45, 0,}; /* no dcache_lock, please */ 64 static inline void d_free(struct dentry *dentry) { 66 if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); 68 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. */ 79 static inline void dentry_iput(struct dentry * dentry) { struct inode *inode = dentry->d_inode; 82 if (inode) { dentry->d_inode = NULL; list_del_init(&dentry->d_alias); 85 spin_unlock(&dcache_lock); 86 if (dentry->d_op && dentry->d_op->d_iput) dentry->d_op->d_iput(dentry, inode); 88 else iput(inode); 90 } else 91 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. */ 123 void dput(struct dentry *dentry) { 125 if (!dentry) 126 return; repeat: 129 if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) 130 return; /* dput on a free dentry? */ 133 if (!list_empty(&dentry->d_lru)) 134 BUG(); /* * AV: ->d_delete() is _NOT_ allowed to block now. */ 138 if (dentry->d_op && dentry->d_op->d_delete) { 139 if (dentry->d_op->d_delete(dentry)) 140 goto unhash_it; } /* Unreachable? Get rid of it */ 143 if (list_empty(&dentry->d_hash)) 144 goto kill_it; list_add(&dentry->d_lru, &dentry_unused); dentry_stat.nr_unused++; /* * Update the timestamp */ dentry->d_reftime = jiffies; 151 spin_unlock(&dcache_lock); 152 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); 164 if (dentry == parent) 165 return; dentry = parent; 167 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. */ 183 int d_invalidate(struct dentry * dentry) { /* * If it's already been dropped, return OK. */ spin_lock(&dcache_lock); 189 if (list_empty(&dentry->d_hash)) { 190 spin_unlock(&dcache_lock); 191 return 0; } /* * Check whether to do a partial shrink_dcache * to get rid of unused child entries. */ 197 if (!list_empty(&dentry->d_subdirs)) { 198 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). */ 213 if (atomic_read(&dentry->d_count) > 1) { 214 if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { 215 spin_unlock(&dcache_lock); 216 return -EBUSY; } } list_del_init(&dentry->d_hash); 221 spin_unlock(&dcache_lock); 222 return 0; } /* This should be called _only_ with dcache_lock held */ 227 static inline struct dentry * __dget_locked(struct dentry *dentry) { atomic_inc(&dentry->d_count); 230 if (atomic_read(&dentry->d_count) == 1) { dentry_stat.nr_unused--; list_del(&dentry->d_lru); 233 INIT_LIST_HEAD(&dentry->d_lru); /* make "list_empty()" work */ } 235 return dentry; } 238 struct dentry * dget_locked(struct dentry *dentry) { 240 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. */ 253 struct dentry * d_find_alias(struct inode *inode) { struct list_head *head, *next, *tmp; struct dentry *alias; spin_lock(&dcache_lock); head = &inode->i_dentry; next = inode->i_dentry.next; 261 while (next != head) { tmp = next; next = tmp->next; alias = list_entry(tmp, struct dentry, d_alias); 265 if (!list_empty(&alias->d_hash)) { __dget_locked(alias); 267 spin_unlock(&dcache_lock); 268 return alias; } } 271 spin_unlock(&dcache_lock); 272 return NULL; } /* * Try to kill dentries associated with this inode. * WARNING: you must own a reference to inode. */ 279 void d_prune_aliases(struct inode *inode) { struct list_head *tmp, *head = &inode->i_dentry; restart: spin_lock(&dcache_lock); tmp = head; 285 while ((tmp = tmp->next) != head) { struct dentry *dentry = list_entry(tmp, struct dentry, d_alias); 287 if (!atomic_read(&dentry->d_count)) { __dget_locked(dentry); 289 spin_unlock(&dcache_lock); d_drop(dentry); dput(dentry); 292 goto restart; } } 295 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. */ 304 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); 313 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. */ 331 void prune_dcache(int count) { spin_lock(&dcache_lock); 334 for (;;) { struct dentry *dentry; struct list_head *tmp; tmp = dentry_unused.prev; 340 if (tmp == &dentry_unused) 341 break; list_del_init(tmp); dentry = list_entry(tmp, struct dentry, d_lru); /* If the dentry was recently referenced, don't free it. */ 346 if (dentry->d_flags & DCACHE_REFERENCED) { dentry->d_flags &= ~DCACHE_REFERENCED; list_add(&dentry->d_lru, &dentry_unused); count--; 350 continue; } dentry_stat.nr_unused--; /* Unused dentry with a count? */ 355 if (atomic_read(&dentry->d_count)) 356 BUG(); prune_one_dentry(dentry); 359 if (!--count) 360 break; } 362 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 */ 387 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; 398 while (next != &dentry_unused) { tmp = next; next = tmp->next; dentry = list_entry(tmp, struct dentry, d_lru); 402 if (dentry->d_sb != sb) 403 continue; list_del(tmp); list_add(tmp, &dentry_unused); } /* * Pass two ... free the dentries for this superblock. */ repeat: next = dentry_unused.next; 413 while (next != &dentry_unused) { tmp = next; next = tmp->next; dentry = list_entry(tmp, struct dentry, d_lru); 417 if (dentry->d_sb != sb) 418 continue; 419 if (atomic_read(&dentry->d_count)) 420 continue; dentry_stat.nr_unused--; list_del(tmp); 423 INIT_LIST_HEAD(tmp); prune_one_dentry(dentry); 425 goto repeat; } 427 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 */ 444 int have_submounts(struct dentry *parent) { struct dentry *this_parent = parent; struct list_head *next; spin_lock(&dcache_lock); 450 if (d_mountpoint(parent)) 451 goto positive; repeat: next = this_parent->d_subdirs.next; resume: 455 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 ? */ 460 if (d_mountpoint(dentry)) 461 goto positive; 462 if (!list_empty(&dentry->d_subdirs)) { this_parent = dentry; 464 goto repeat; } } /* * All done at this level ... ascend and resume the search. */ 470 if (this_parent != parent) { next = this_parent->d_child.next; this_parent = this_parent->d_parent; 473 goto resume; } 475 spin_unlock(&dcache_lock); 476 return 0; /* No mount points found in tree */ positive: 478 spin_unlock(&dcache_lock); 479 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. */ 489 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: 499 while (next != &this_parent->d_subdirs) { struct list_head *tmp = next; struct dentry *dentry = list_entry(tmp, struct dentry, d_child); next = tmp->next; 503 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. */ 511 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 517 goto repeat; } } /* * All done at this level ... ascend and resume the search. */ 523 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 530 goto resume; } 532 spin_unlock(&dcache_lock); 533 return found; } /** * shrink_dcache_parent - prune dcache * @parent: parent of entries to prune * * Prune the dcache to remove unused children of the parent dentry. */ 543 void shrink_dcache_parent(struct dentry * parent) { int found; 547 while ((found = select_parent(parent)) != 0) prune_dcache(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: * 0 - very urgent: shrink everything * ... * 6 - base-level: try to shrink a bit. */ 562 void 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: */ 577 if (!(gfp_mask & __GFP_IO)) 578 return; 580 if (priority) count = dentry_stat.nr_unused / priority; prune_dcache(count); kmem_cache_shrink(dentry_cache); } #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. */ 599 struct dentry * d_alloc(struct dentry * parent, const struct qstr *name) { char * str; struct dentry *dentry; dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); 605 if (!dentry) 606 return NULL; 608 if (name->len > DNAME_INLINE_LEN-1) { str = kmalloc(NAME_ALLOC_LEN(name->len), GFP_KERNEL); 610 if (!str) { kmem_cache_free(dentry_cache, dentry); 612 return NULL; } 614 } else str = dentry->d_iname; memcpy(str, name->name, name->len); str[name->len] = 0; atomic_set(&dentry->d_count, 1); 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; 630 INIT_LIST_HEAD(&dentry->d_vfsmnt); 631 INIT_LIST_HEAD(&dentry->d_hash); 632 INIT_LIST_HEAD(&dentry->d_lru); 633 INIT_LIST_HEAD(&dentry->d_subdirs); 634 INIT_LIST_HEAD(&dentry->d_alias); 635 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); 640 spin_unlock(&dcache_lock); 641 } else 642 INIT_LIST_HEAD(&dentry->d_child); dentry_stat.nr_dentry++; 645 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. */ 663 void d_instantiate(struct dentry *entry, struct inode * inode) { spin_lock(&dcache_lock); 666 if (inode) list_add(&entry->d_alias, &inode->i_dentry); entry->d_inode = inode; 669 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. */ 681 struct dentry * d_alloc_root(struct inode * root_inode) { struct dentry *res = NULL; 685 if (root_inode) { res = d_alloc(NULL, &(const struct qstr) { "/", 1, 0 }); 687 if (res) { res->d_sb = root_inode->i_sb; res->d_parent = res; d_instantiate(res, root_inode); } } 693 return res; } 696 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) ^ (hash >> D_HASHBITS*2); 700 return dentry_hashtable + (hash & D_HASHMASK); } /** * 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. */ 714 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; spin_lock(&dcache_lock); tmp = head->next; 724 for (;;) { struct dentry * dentry = list_entry(tmp, struct dentry, d_hash); 726 if (tmp == head) 727 break; tmp = tmp->next; 729 if (dentry->d_name.hash != hash) 730 continue; 731 if (dentry->d_parent != parent) 732 continue; 733 if (parent->d_op && parent->d_op->d_compare) { 734 if (parent->d_op->d_compare(parent, &dentry->d_name, name)) 735 continue; 736 } else { 737 if (dentry->d_name.len != len) 738 continue; 739 if (memcmp(dentry->d_name.name, str, len)) 740 continue; } __dget_locked(dentry); dentry->d_flags |= DCACHE_REFERENCED; 744 spin_unlock(&dcache_lock); 745 return dentry; } 747 spin_unlock(&dcache_lock); 748 return NULL; } /** * d_validate - verify dentry provided from insecure source * @dentry: The dentry alleged to be valid * @dparent: The parent dentry * @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. * * NOTE: This function does _not_ dereference the pointers before we have * validated them. We can test the pointer values, but we * must not actually use them until we have found a valid * copy of the pointer in kernel space.. */ 768 int d_validate(struct dentry *dentry, struct dentry *dparent, unsigned int hash, unsigned int len) { struct list_head *base, *lhp; int valid = 1; spin_lock(&dcache_lock); 775 if (dentry != dparent) { base = d_hash(dparent, hash); lhp = base; 778 while ((lhp = lhp->next) != base) { 779 if (dentry == list_entry(lhp, struct dentry, d_hash)) { __dget_locked(dentry); 781 goto out; } } 784 } else { /* * Special case: local mount points don't live in * the hashes, so we search the super blocks. */ struct super_block *sb = sb_entry(super_blocks.next); 791 for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.next)) { if (!sb->s_dev) continue; if (sb->s_root == dentry) { __dget_locked(dentry); goto out; } } } valid = 0; out: 803 spin_unlock(&dcache_lock); 804 return valid; } /* * 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 */ 828 void d_delete(struct dentry * dentry) { /* * Are we the only user? */ spin_lock(&dcache_lock); 834 if (atomic_read(&dentry->d_count) == 1) { dentry_iput(dentry); 836 return; } 838 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. */ 854 void d_rehash(struct dentry * entry) { struct list_head *list = d_hash(entry->d_parent, entry->d_name.hash); spin_lock(&dcache_lock); list_add(&entry->d_hash, list); 859 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.. */ 877 static inline void switch_names(struct dentry * dentry, struct dentry * target) { const unsigned char *old_name, *new_name; 881 check_lock(); memcpy(dentry->d_iname, target->d_iname, DNAME_INLINE_LEN); old_name = target->d_name.name; new_name = dentry->d_name.name; 885 if (old_name == target->d_iname) old_name = dentry->d_iname; 887 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. */ 918 void d_move(struct dentry * dentry, struct dentry * target) { 920 check_lock(); 922 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(&target->d_hash); 932 INIT_LIST_HEAD(&target->d_hash); list_del(&dentry->d_child); list_del(&target->d_child); /* Switch the parents and the names.. */ switch_names(dentry, target); 939 do_switch(dentry->d_parent, target->d_parent); 940 do_switch(dentry->d_name.len, target->d_name.len); 941 do_switch(dentry->d_name.hash, target->d_name.hash); /* And add them back to the (new) parent lists */ list_add(&target->d_child, &target->d_parent->d_subdirs); list_add(&dentry->d_child, &dentry->d_parent->d_subdirs); 946 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. */ 964 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--; 974 if (!IS_ROOT(dentry) && list_empty(&dentry->d_hash)) { buflen -= 10; end -= 10; memcpy(end, " (deleted)", 10); } /* Get '/' right */ retval = end-1; *retval = '/'; 984 for (;;) { struct dentry * parent; 987 if (dentry == root && vfsmnt == rootmnt) 988 break; 989 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { /* Global root? */ 991 if (vfsmnt->mnt_parent == vfsmnt) 992 goto global_root; dentry = vfsmnt->mnt_mountpoint; vfsmnt = vfsmnt->mnt_parent; 995 continue; } parent = dentry->d_parent; namelen = dentry->d_name.len; buflen -= namelen + 1; 1000 if (buflen < 0) 1001 break; end -= namelen; memcpy(end, dentry->d_name.name, namelen); *--end = '/'; retval = end; dentry = parent; } 1008 return retval; global_root: namelen = dentry->d_name.len; buflen -= namelen; 1012 if (buflen >= 0) { retval -= namelen-1; /* hit the slash */ memcpy(retval, dentry->d_name.name, namelen); } 1016 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; * } */ 1037 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); 1044 if (!page) 1045 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); 1052 read_unlock(¤t->fs->lock); error = -ENOENT; /* Has the current directory has been unlinked? */ spin_lock(&dcache_lock); 1057 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); 1062 spin_unlock(&dcache_lock); error = -ERANGE; len = PAGE_SIZE + page - cwd; 1066 if (len <= size) { error = len; 1068 if (copy_to_user(buf, cwd, len)) error = -EFAULT; } 1071 } else 1072 spin_unlock(&dcache_lock); dput(pwd); mntput(pwdmnt); dput(root); mntput(rootmnt); free_page((unsigned long) page); 1078 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. */ 1096 int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry) { int result; result = 0; 1101 for (;;) { 1102 if (new_dentry != old_dentry) { struct dentry * parent = new_dentry->d_parent; 1104 if (parent == new_dentry) 1105 break; new_dentry = parent; 1107 continue; } result = 1; 1110 break; } 1112 return result; } 1115 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: 1124 while (next != &this_parent->d_subdirs) { struct list_head *tmp = next; struct dentry *dentry = list_entry(tmp, struct dentry, d_child); next = tmp->next; 1128 if (d_unhashed(dentry)||!dentry->d_inode) 1129 continue; 1130 if (!list_empty(&dentry->d_subdirs)) { this_parent = dentry; 1132 goto repeat; } atomic_dec(&dentry->d_count); } 1136 if (this_parent != root) { next = this_parent->d_child.next; atomic_dec(&this_parent->d_count); this_parent = this_parent->d_parent; 1140 goto resume; } 1142 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. */ 1159 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); 1170 if (dir->d_op && dir->d_op->d_hash) { 1172 if (dir->d_op->d_hash(dir, name) != 0) 1173 goto out; } dentry = d_lookup(dir, name); 1177 if (dentry) { 1179 if (dentry->d_inode) ino = dentry->d_inode->i_ino; dput(dentry); } out: 1184 return ino; } 1187 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); 1207 if (!dentry_cache) panic("Cannot create dentry cache"); #if PAGE_SHIFT < 13 mempages >>= (13 - PAGE_SHIFT); #endif mempages *= sizeof(struct list_head); 1214 for (order = 0; ((1UL << order) << PAGE_SHIFT) < mempages; order++) ; 1217 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; 1226 while ((tmp >>= 1UL) != 0UL) d_hash_shift++; dentry_hashtable = (struct list_head *) __get_free_pages(GFP_ATOMIC, order); 1231 } while (dentry_hashtable == NULL && --order >= 0); printk("Dentry-cache hash table entries: %d (order: %ld, %ld bytes)\n", nr_hash, order, (PAGE_SIZE << order)); 1236 if (!dentry_hashtable) panic("Failed to allocate dcache hash table\n"); d = dentry_hashtable; i = nr_hash; 1241 do { 1242 INIT_LIST_HEAD(d); d++; i--; 1245 } 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; /* SLAB cache for buffer_head structures */ kmem_cache_t *bh_cachep; 1260 void __init vfs_caches_init(unsigned long mempages) { bh_cachep = kmem_cache_create("buffer_head", sizeof(struct buffer_head), 0, SLAB_HWCACHE_ALIGN, NULL, NULL); 1265 if(!bh_cachep) panic("Cannot create buffer head SLAB cache"); names_cachep = kmem_cache_create("names_cache", PATH_MAX + 1, 0, SLAB_HWCACHE_ALIGN, NULL, NULL); 1271 if (!names_cachep) panic("Cannot create names SLAB cache"); filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, SLAB_HWCACHE_ALIGN, NULL, NULL); 1277 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); }