X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=fs%2Fdcache.c;h=2355bddad8de12609bcc0b517a151883638c79eb;hb=b517bea1c74e4773482b3f41b3f493522a8c8e30;hp=1b4a3a34ec57f20d605386c129c9ebf315dd1765;hpb=912b2539e1e062cec73e2e61448e507f7719bd08;p=powerpc.git diff --git a/fs/dcache.c b/fs/dcache.c index 1b4a3a34ec..2355bddad8 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; @@ -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); @@ -828,17 +830,19 @@ 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 +855,35 @@ 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 +1005,7 @@ 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 +1255,11 @@ 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 +1269,9 @@ 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); } @@ -1386,6 +1409,120 @@ already_unhashed: spin_unlock(&dcache_lock); } +/* + * 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 *alias, *actual; + + BUG_ON(!d_unhashed(dentry)); + + spin_lock(&dcache_lock); + + if (!inode) { + actual = dentry; + dentry->d_inode = NULL; + goto found_lock; + } + + /* See if a disconnected directory already exists as an anonymous root + * that we should splice into the tree instead */ + if (S_ISDIR(inode->i_mode) && (alias = __d_find_alias(inode, 1))) { + spin_lock(&alias->d_lock); + + /* Is this a mountpoint that we could splice into our tree? */ + if (IS_ROOT(alias)) + goto connect_mountpoint; + + if (alias->d_name.len == dentry->d_name.len && + alias->d_parent == dentry->d_parent && + memcmp(alias->d_name.name, + dentry->d_name.name, + dentry->d_name.len) == 0) + goto replace_with_alias; + + spin_unlock(&alias->d_lock); + + /* Doh! Seem to be aliasing directories for some reason... */ + dput(alias); + } + + /* 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); + + if (actual == dentry) { + security_d_instantiate(dentry, inode); + return NULL; + } + + iput(inode); + return actual; + + /* Convert the anonymous/root alias into an ordinary dentry */ +connect_mountpoint: + __d_materialise_dentry(dentry, alias); + + /* Replace the candidate dentry with the alias in the tree */ +replace_with_alias: + __d_drop(alias); + actual = alias; + goto found; + +shouldnt_be_hashed: + spin_unlock(&dcache_lock); + BUG(); + goto shouldnt_be_hashed; +} + /** * d_path - return the path of a dentry * @dentry: dentry to report @@ -1742,9 +1879,6 @@ kmem_cache_t *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 +1918,7 @@ 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);