diff options
| -rw-r--r-- | fs/dcache.c | 135 |
1 files changed, 61 insertions, 74 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index d1840b30c67..dc0551c9755 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -284,6 +284,40 @@ void d_drop(struct dentry *dentry) } EXPORT_SYMBOL(d_drop); +/* + * Finish off a dentry we've decided to kill. + * dentry->d_lock must be held, returns with it unlocked. + * If ref is non-zero, then decrement the refcount too. + * Returns dentry requiring refcount drop, or NULL if we're done. + */ +static inline struct dentry *dentry_kill(struct dentry *dentry, int ref) + __releases(dentry->d_lock) +{ + struct dentry *parent; + + if (!spin_trylock(&dcache_inode_lock)) { +relock: + spin_unlock(&dentry->d_lock); + cpu_relax(); + return dentry; /* try again with same dentry */ + } + 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; + } + if (ref) + 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 then remove it */ + __d_drop(dentry); + return d_kill(dentry, parent); +} + /* * This is dput * @@ -309,13 +343,9 @@ EXPORT_SYMBOL(d_drop); * 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; @@ -348,26 +378,7 @@ repeat: 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); + dentry = dentry_kill(dentry, 1); if (dentry) goto repeat; } @@ -563,51 +574,43 @@ restart: 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 throw away a dentry - free the inode, dput the parent. + * Requires dentry->d_lock is held, and dentry->d_count == 0. + * Releases dentry->d_lock. * - * 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. + * This may fail if locks cannot be acquired no problem, just try again. */ -static void prune_one_dentry(struct dentry *dentry, struct dentry *parent) +static void try_prune_one_dentry(struct dentry *dentry) __releases(dentry->d_lock) - __releases(parent->d_lock) - __releases(dcache_inode_lock) { - __d_drop(dentry); - dentry = d_kill(dentry, parent); + struct dentry *parent; + parent = dentry_kill(dentry, 0); /* - * Prune ancestors. + * If dentry_kill returns NULL, we have nothing more to do. + * if it returns the same dentry, trylocks failed. In either + * case, just loop again. + * + * Otherwise, we need to prune ancestors too. This is necessary + * to prevent quadratic behavior of shrink_dcache_parent(), but + * is also expected to be beneficial in reducing dentry cache + * fragmentation. */ + if (!parent) + return; + if (parent == dentry) + return; + + /* Prune ancestors. */ + dentry = parent; while (dentry) { -relock: spin_lock(&dentry->d_lock); if (dentry->d_count > 1) { dentry->d_count--; spin_unlock(&dentry->d_lock); return; } - if (!spin_trylock(&dcache_inode_lock)) { -relock2: - spin_unlock(&dentry->d_lock); - cpu_relax(); - goto relock; - } - - if (IS_ROOT(dentry)) - parent = NULL; - else - parent = dentry->d_parent; - if (parent && !spin_trylock(&parent->d_lock)) { - spin_unlock(&dcache_inode_lock); - goto relock2; - } - dentry->d_count--; - dentry_lru_del(dentry); - __d_drop(dentry); - dentry = d_kill(dentry, parent); + dentry = dentry_kill(dentry, 1); } } @@ -617,8 +620,6 @@ static void shrink_dentry_list(struct list_head *list) rcu_read_lock(); for (;;) { - struct dentry *parent; - dentry = list_entry_rcu(list->prev, struct dentry, d_lru); if (&dentry->d_lru == list) break; /* empty */ @@ -639,24 +640,10 @@ static void shrink_dentry_list(struct list_head *list) continue; } - if (!spin_trylock(&dcache_inode_lock)) { -relock: - spin_unlock(&dentry->d_lock); - cpu_relax(); - continue; - } - 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_lru_del(dentry); - rcu_read_unlock(); - prune_one_dentry(dentry, parent); + + try_prune_one_dentry(dentry); + rcu_read_lock(); } rcu_read_unlock(); |