X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=fs%2Fdcache.c;h=d68631f18df122824a0d36a307c647f15931c7bd;hb=d5112a4f31a361409d3c57dc9d58dd69f8014bef;hp=2bac4ba1d1d3755b70598e992847459dc889a962;hpb=60ca97584fcb98d2f1b14e4c2f12203dd5b3888e;p=linux-2.6 diff --git a/fs/dcache.c b/fs/dcache.c index 2bac4ba1d1..d68631f18d 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -43,7 +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)) @@ -68,15 +68,19 @@ struct dentry_stat_t dentry_stat = { .age_limit = 45, }; -static void d_callback(struct rcu_head *head) +static void __d_free(struct dentry *dentry) { - struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); - if (dname_external(dentry)) kfree(dentry->d_name.name); kmem_cache_free(dentry_cache, dentry); } +static void d_callback(struct rcu_head *head) +{ + struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); + __d_free(dentry); +} + /* * no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry * inside dcache_lock. @@ -85,7 +89,11 @@ static void d_free(struct dentry *dentry) { if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); - call_rcu(&dentry->d_u.d_rcu, d_callback); + /* if dentry was never inserted into hash, immediate free is OK */ + if (dentry->d_hash.pprev == NULL) + __d_free(dentry); + else + call_rcu(&dentry->d_u.d_rcu, d_callback); } /* @@ -478,11 +486,12 @@ 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); } @@ -556,6 +565,7 @@ repeat: static void shrink_dcache_for_umount_subtree(struct dentry *dentry) { struct dentry *parent; + unsigned detached = 0; BUG_ON(!IS_ROOT(dentry)); @@ -620,7 +630,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) atomic_dec(&parent->d_count); list_del(&dentry->d_u.d_child); - dentry_stat.nr_dentry--; /* For d_free, below */ + detached++; inode = dentry->d_inode; if (inode) { @@ -638,7 +648,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) * otherwise we ascend to the parent and move to the * next sibling if there is one */ if (!parent) - return; + goto out; dentry = parent; @@ -647,6 +657,11 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) 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); } /* @@ -1469,23 +1484,21 @@ 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? @@ -1536,7 +1549,81 @@ 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; } /* @@ -1581,7 +1668,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) */ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) { - struct dentry *alias, *actual; + struct dentry *actual; BUG_ON(!d_unhashed(dentry)); @@ -1593,26 +1680,27 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) 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); + 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 */ @@ -1628,7 +1716,7 @@ 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; @@ -1637,16 +1725,6 @@ found: 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(); @@ -2002,10 +2080,10 @@ 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);