X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=fs%2Fdcache.c;h=a7c67cee5d83be18e20f0251b745d7a3e2d23916;hb=910b1b2e6d7d10e1c3bffdd12a90ec82f535f9a5;hp=1b4a3a34ec57f20d605386c129c9ebf315dd1765;hpb=51bece910d2b0aca64cd3dee9fa2a8aa7feeadd9;p=mv-sheeva.git diff --git a/fs/dcache.c b/fs/dcache.c index 1b4a3a34ec5..a7c67cee5d8 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -32,6 +32,7 @@ #include #include #include +#include "internal.h" int sysctl_vfs_cache_pressure __read_mostly = 100; @@ -42,7 +43,7 @@ static __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); EXPORT_SYMBOL(dcache_lock); -static kmem_cache_t *dentry_cache __read_mostly; +static struct kmem_cache *dentry_cache __read_mostly; #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) @@ -290,9 +291,9 @@ struct dentry * dget_locked(struct dentry *dentry) * it can be unhashed only if it has no children, or if it is the root * of a filesystem. * - * If the inode has a DCACHE_DISCONNECTED alias, then prefer + * 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 a DCACHE_DISCONNECTED alias. + * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. */ static struct dentry * __d_find_alias(struct inode *inode, int want_discon) @@ -308,7 +309,8 @@ static struct dentry * __d_find_alias(struct inode *inode, int want_discon) prefetch(next); alias = list_entry(tmp, struct dentry, d_alias); if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { - if (alias->d_flags & DCACHE_DISCONNECTED) + if (IS_ROOT(alias) && + (alias->d_flags & DCACHE_DISCONNECTED)) discon_alias = alias; else if (!want_discon) { __dget_locked(alias); @@ -476,11 +478,12 @@ static void prune_dcache(int count, struct super_block *sb) up_read(s_umount); } spin_unlock(&dentry->d_lock); - /* Cannot remove the first dentry, and it isn't appropriate - * to move it to the head of the list, so give up, and try - * later + /* + * Insert dentry at the head of the list as inserting at the + * tail leads to a cycle. */ - break; + list_add(&dentry->d_lru, &dentry_unused); + dentry_stat.nr_unused++; } spin_unlock(&dcache_lock); } @@ -546,6 +549,142 @@ repeat: spin_unlock(&dcache_lock); } +/* + * 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(&dcache_lock); + if (!list_empty(&dentry->d_lru)) { + dentry_stat.nr_unused--; + list_del_init(&dentry->d_lru); + } + __d_drop(dentry); + spin_unlock(&dcache_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(&dcache_lock); + list_for_each_entry(loop, &dentry->d_subdirs, + d_u.d_child) { + if (!list_empty(&loop->d_lru)) { + dentry_stat.nr_unused--; + list_del_init(&loop->d_lru); + } + + __d_drop(loop); + cond_resched_lock(&dcache_lock); + } + spin_unlock(&dcache_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 (atomic_read(&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, + atomic_read(&dentry->d_count), + dentry->d_sb->s_type->name, + dentry->d_sb->s_id); + BUG(); + } + + parent = dentry->d_parent; + if (parent == dentry) + parent = NULL; + else + atomic_dec(&parent->d_count); + + list_del(&dentry->d_u.d_child); + 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) + goto out; + + dentry = parent; + + } while (list_empty(&dentry->d_subdirs)); + + dentry = list_entry(dentry->d_subdirs.next, + struct dentry, d_u.d_child); + } +out: + /* several dentries were freed, need to correct nr_dentry */ + spin_lock(&dcache_lock); + dentry_stat.nr_dentry -= detached; + spin_unlock(&dcache_lock); +} + +/* + * destroy the dentries attached to a superblock on unmounting + * - we don't need to use dentry->d_lock, and only need dcache_lock when + * removing the dentry from the system lists and hashes 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; + atomic_dec(&dentry->d_count); + 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 @@ -828,17 +967,19 @@ void d_instantiate(struct dentry *entry, struct inode * inode) * (or otherwise set) by the caller to indicate that it is now * in use by the dcache. */ -struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) +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; - BUG_ON(!list_empty(&entry->d_alias)); - spin_lock(&dcache_lock); - if (!inode) - goto do_negative; + if (!inode) { + entry->d_inode = NULL; + return NULL; + } + list_for_each_entry(alias, &inode->i_dentry, d_alias) { struct qstr *qstr = &alias->d_name; @@ -851,19 +992,35 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) if (memcmp(qstr->name, name, len)) continue; dget_locked(alias); - spin_unlock(&dcache_lock); - BUG_ON(!d_unhashed(alias)); - iput(inode); return alias; } + list_add(&entry->d_alias, &inode->i_dentry); -do_negative: entry->d_inode = inode; fsnotify_d_instantiate(entry, inode); - spin_unlock(&dcache_lock); - security_d_instantiate(entry, inode); return NULL; } + +struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) +{ + struct dentry *result; + + BUG_ON(!list_empty(&entry->d_alias)); + + spin_lock(&dcache_lock); + result = __d_instantiate_unique(entry, inode); + spin_unlock(&dcache_lock); + + if (!result) { + security_d_instantiate(entry, inode); + return NULL; + } + + BUG_ON(!d_unhashed(result)); + iput(inode); + return result; +} + EXPORT_SYMBOL(d_instantiate_unique); /** @@ -985,7 +1142,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) { struct dentry *new = NULL; - if (inode) { + if (inode && S_ISDIR(inode->i_mode)) { spin_lock(&dcache_lock); new = __d_find_alias(inode, 1); if (new) { @@ -1235,6 +1392,11 @@ static void __d_rehash(struct dentry * entry, struct hlist_head *list) 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 @@ -1244,11 +1406,9 @@ static void __d_rehash(struct dentry * entry, struct hlist_head *list) void d_rehash(struct dentry * entry) { - struct hlist_head *list = d_hash(entry->d_parent, entry->d_name.hash); - spin_lock(&dcache_lock); spin_lock(&entry->d_lock); - __d_rehash(entry, list); + _d_rehash(entry); spin_unlock(&entry->d_lock); spin_unlock(&dcache_lock); } @@ -1316,23 +1476,21 @@ static void switch_names(struct dentry *dentry, struct dentry *target) * deleted it. */ -/** - * d_move - move a dentry +/* + * d_move_locked - 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) +static void d_move_locked(struct dentry * dentry, struct dentry * target) { struct hlist_head *list; if (!dentry->d_inode) printk(KERN_WARNING "VFS: moving negative dcache entry\n"); - spin_lock(&dcache_lock); write_seqlock(&rename_lock); /* * XXXX: do we really need to take target->d_lock? @@ -1383,9 +1541,188 @@ already_unhashed: fsnotify_d_move(dentry); spin_unlock(&dentry->d_lock); write_sequnlock(&rename_lock); +} + +/** + * 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) +{ + spin_lock(&dcache_lock); + d_move_locked(dentry, target); spin_unlock(&dcache_lock); } +/* + * Helper that returns 1 if p1 is a parent of p2, else 0 + */ +static int d_isparent(struct dentry *p1, struct dentry *p2) +{ + struct dentry *p; + + for (p = p2; p->d_parent != p; p = p->d_parent) { + if (p->d_parent == p1) + return 1; + } + return 0; +} + +/* + * 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_lock + * + * Note: If ever the locking in lock_rename() changes, then please + * remember to update this too... + * + * On return, dcache_lock will have been unlocked. + */ +static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) +{ + 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_isparent(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_locked(alias, dentry); + ret = alias; +out_err: + spin_unlock(&dcache_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. + */ +static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) +{ + struct dentry *dparent, *aparent; + + switch_names(dentry, anon); + do_switch(dentry->d_name.len, anon->d_name.len); + do_switch(dentry->d_name.hash, anon->d_name.hash); + + dparent = dentry->d_parent; + aparent = anon->d_parent; + + 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); + + 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_lock); + + if (!inode) { + actual = dentry; + dentry->d_inode = 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)) { + spin_lock(&alias->d_lock); + __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: + _d_rehash(actual); + spin_unlock(&actual->d_lock); + spin_unlock(&dcache_lock); +out_nolock: + if (actual == dentry) { + security_d_instantiate(dentry, inode); + return NULL; + } + + iput(inode); + return actual; + +shouldnt_be_hashed: + spin_unlock(&dcache_lock); + BUG(); + goto shouldnt_be_hashed; +} + /** * d_path - return the path of a dentry * @dentry: dentry to report @@ -1735,16 +2072,13 @@ static void __init dcache_init(unsigned long mempages) } /* SLAB cache for __getname() consumers */ -kmem_cache_t *names_cachep __read_mostly; +struct kmem_cache *names_cachep __read_mostly; /* SLAB cache for file structures */ -kmem_cache_t *filp_cachep __read_mostly; +struct kmem_cache *filp_cachep __read_mostly; EXPORT_SYMBOL(d_genocide); -extern void bdev_cache_init(void); -extern void chrdev_init(void); - void __init vfs_caches_init_early(void) { dcache_init_early(); @@ -1784,6 +2118,7 @@ EXPORT_SYMBOL(d_instantiate); EXPORT_SYMBOL(d_invalidate); EXPORT_SYMBOL(d_lookup); EXPORT_SYMBOL(d_move); +EXPORT_SYMBOL_GPL(d_materialise_unique); EXPORT_SYMBOL(d_path); EXPORT_SYMBOL(d_prune_aliases); EXPORT_SYMBOL(d_rehash);