fs/mbcache.c: doucple the locking of local from global data
The patch increases the parallelism of mbcache by using the built-in lock in the hlist_bl_node to protect the mb_cache's local block and index hash chains. The global data mb_cache_lru_list and mb_cache_list continue to be protected by the global mb_cache_spinlock. New block group spinlock, mb_cache_bg_lock is also added to serialize accesses to mb_cache_entry's local data. A new member e_refcnt is added to the mb_cache_entry structure to help preventing an mb_cache_entry from being deallocated by a free while it is being referenced by either mb_cache_entry_get() or mb_cache_entry_find(). Signed-off-by: T. Makphaibulchoke <tmac@hp.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
parent
3e037e5211
commit
1f3e55fe02
421
fs/mbcache.c
421
fs/mbcache.c
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@ -26,6 +26,41 @@
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* back on the lru list.
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*/
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/*
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* Lock descriptions and usage:
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*
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* Each hash chain of both the block and index hash tables now contains
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* a built-in lock used to serialize accesses to the hash chain.
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*
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* Accesses to global data structures mb_cache_list and mb_cache_lru_list
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* are serialized via the global spinlock mb_cache_spinlock.
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*
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* Each mb_cache_entry contains a spinlock, e_entry_lock, to serialize
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* accesses to its local data, such as e_used and e_queued.
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*
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* Lock ordering:
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*
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* Each block hash chain's lock has the highest lock order, followed by an
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* index hash chain's lock, mb_cache_bg_lock (used to implement mb_cache_entry's
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* lock), and mb_cach_spinlock, with the lowest order. While holding
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* either a block or index hash chain lock, a thread can acquire an
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* mc_cache_bg_lock, which in turn can also acquire mb_cache_spinlock.
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*
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* Synchronization:
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*
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* Since both mb_cache_entry_get and mb_cache_entry_find scan the block and
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* index hash chian, it needs to lock the corresponding hash chain. For each
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* mb_cache_entry within the chain, it needs to lock the mb_cache_entry to
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* prevent either any simultaneous release or free on the entry and also
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* to serialize accesses to either the e_used or e_queued member of the entry.
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*
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* To avoid having a dangling reference to an already freed
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* mb_cache_entry, an mb_cache_entry is only freed when it is not on a
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* block hash chain and also no longer being referenced, both e_used,
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* and e_queued are 0's. When an mb_cache_entry is explicitly freed it is
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* first removed from a block hash chain.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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@ -37,6 +72,7 @@
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#include <linux/list_bl.h>
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#include <linux/mbcache.h>
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#include <linux/init.h>
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#include <linux/blockgroup_lock.h>
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#ifdef MB_CACHE_DEBUG
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# define mb_debug(f...) do { \
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@ -57,8 +93,13 @@
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#define MB_CACHE_WRITER ((unsigned short)~0U >> 1)
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#define MB_CACHE_ENTRY_LOCK_BITS __builtin_log2(NR_BG_LOCKS)
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#define MB_CACHE_ENTRY_LOCK_INDEX(ce) \
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(hash_long((unsigned long)ce, MB_CACHE_ENTRY_LOCK_BITS))
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static DECLARE_WAIT_QUEUE_HEAD(mb_cache_queue);
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static struct blockgroup_lock *mb_cache_bg_lock;
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MODULE_AUTHOR("Andreas Gruenbacher <a.gruenbacher@computer.org>");
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MODULE_DESCRIPTION("Meta block cache (for extended attributes)");
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MODULE_LICENSE("GPL");
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@ -86,6 +127,20 @@ static LIST_HEAD(mb_cache_list);
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static LIST_HEAD(mb_cache_lru_list);
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static DEFINE_SPINLOCK(mb_cache_spinlock);
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static inline void
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__spin_lock_mb_cache_entry(struct mb_cache_entry *ce)
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{
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spin_lock(bgl_lock_ptr(mb_cache_bg_lock,
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MB_CACHE_ENTRY_LOCK_INDEX(ce)));
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}
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static inline void
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__spin_unlock_mb_cache_entry(struct mb_cache_entry *ce)
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{
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spin_unlock(bgl_lock_ptr(mb_cache_bg_lock,
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MB_CACHE_ENTRY_LOCK_INDEX(ce)));
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}
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static inline int
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__mb_cache_entry_is_block_hashed(struct mb_cache_entry *ce)
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{
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@ -113,11 +168,21 @@ __mb_cache_entry_unhash_index(struct mb_cache_entry *ce)
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hlist_bl_del_init(&ce->e_index.o_list);
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}
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/*
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* __mb_cache_entry_unhash_unlock()
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*
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* This function is called to unhash both the block and index hash
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* chain.
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* It assumes both the block and index hash chain is locked upon entry.
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* It also unlock both hash chains both exit
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*/
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static inline void
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__mb_cache_entry_unhash(struct mb_cache_entry *ce)
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__mb_cache_entry_unhash_unlock(struct mb_cache_entry *ce)
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{
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__mb_cache_entry_unhash_index(ce);
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hlist_bl_unlock(ce->e_index_hash_p);
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__mb_cache_entry_unhash_block(ce);
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hlist_bl_unlock(ce->e_block_hash_p);
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}
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static void
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@ -125,36 +190,47 @@ __mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
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{
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struct mb_cache *cache = ce->e_cache;
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mb_assert(!(ce->e_used || ce->e_queued));
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mb_assert(!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt)));
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kmem_cache_free(cache->c_entry_cache, ce);
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atomic_dec(&cache->c_entry_count);
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}
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static void
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__mb_cache_entry_release_unlock(struct mb_cache_entry *ce)
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__releases(mb_cache_spinlock)
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__mb_cache_entry_release(struct mb_cache_entry *ce)
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{
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/* First lock the entry to serialize access to its local data. */
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__spin_lock_mb_cache_entry(ce);
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/* Wake up all processes queuing for this cache entry. */
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if (ce->e_queued)
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wake_up_all(&mb_cache_queue);
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if (ce->e_used >= MB_CACHE_WRITER)
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ce->e_used -= MB_CACHE_WRITER;
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/*
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* Make sure that all cache entries on lru_list have
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* both e_used and e_qued of 0s.
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*/
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ce->e_used--;
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if (!(ce->e_used || ce->e_queued)) {
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if (!__mb_cache_entry_is_block_hashed(ce))
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if (!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))) {
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if (!__mb_cache_entry_is_block_hashed(ce)) {
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__spin_unlock_mb_cache_entry(ce);
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goto forget;
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mb_assert(list_empty(&ce->e_lru_list));
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list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
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}
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/*
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* Need access to lru list, first drop entry lock,
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* then reacquire the lock in the proper order.
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*/
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spin_lock(&mb_cache_spinlock);
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if (list_empty(&ce->e_lru_list))
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list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
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spin_unlock(&mb_cache_spinlock);
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}
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spin_unlock(&mb_cache_spinlock);
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__spin_unlock_mb_cache_entry(ce);
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return;
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forget:
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spin_unlock(&mb_cache_spinlock);
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mb_assert(list_empty(&ce->e_lru_list));
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__mb_cache_entry_forget(ce, GFP_KERNEL);
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}
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/*
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* mb_cache_shrink_scan() memory pressure callback
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*
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mb_debug("trying to free %d entries", nr_to_scan);
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spin_lock(&mb_cache_spinlock);
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while (nr_to_scan-- && !list_empty(&mb_cache_lru_list)) {
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while ((nr_to_scan-- > 0) && !list_empty(&mb_cache_lru_list)) {
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struct mb_cache_entry *ce =
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list_entry(mb_cache_lru_list.next,
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struct mb_cache_entry, e_lru_list);
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list_move_tail(&ce->e_lru_list, &free_list);
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__mb_cache_entry_unhash(ce);
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freed++;
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struct mb_cache_entry, e_lru_list);
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list_del_init(&ce->e_lru_list);
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if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))
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continue;
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spin_unlock(&mb_cache_spinlock);
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/* Prevent any find or get operation on the entry */
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hlist_bl_lock(ce->e_block_hash_p);
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hlist_bl_lock(ce->e_index_hash_p);
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/* Ignore if it is touched by a find/get */
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if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt) ||
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!list_empty(&ce->e_lru_list)) {
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hlist_bl_unlock(ce->e_index_hash_p);
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hlist_bl_unlock(ce->e_block_hash_p);
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spin_lock(&mb_cache_spinlock);
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continue;
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}
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__mb_cache_entry_unhash_unlock(ce);
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list_add_tail(&ce->e_lru_list, &free_list);
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spin_lock(&mb_cache_spinlock);
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}
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spin_unlock(&mb_cache_spinlock);
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list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
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__mb_cache_entry_forget(entry, gfp_mask);
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freed++;
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}
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return freed;
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}
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@ -232,6 +325,14 @@ mb_cache_create(const char *name, int bucket_bits)
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int n, bucket_count = 1 << bucket_bits;
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struct mb_cache *cache = NULL;
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if (!mb_cache_bg_lock) {
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mb_cache_bg_lock = kmalloc(sizeof(struct blockgroup_lock),
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GFP_KERNEL);
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if (!mb_cache_bg_lock)
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return NULL;
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bgl_lock_init(mb_cache_bg_lock);
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}
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cache = kmalloc(sizeof(struct mb_cache), GFP_KERNEL);
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if (!cache)
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return NULL;
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mb_cache_shrink(struct block_device *bdev)
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{
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LIST_HEAD(free_list);
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struct list_head *l, *ltmp;
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struct list_head *l;
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struct mb_cache_entry *ce, *tmp;
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l = &mb_cache_lru_list;
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spin_lock(&mb_cache_spinlock);
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list_for_each_safe(l, ltmp, &mb_cache_lru_list) {
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struct mb_cache_entry *ce =
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list_entry(l, struct mb_cache_entry, e_lru_list);
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while (!list_is_last(l, &mb_cache_lru_list)) {
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l = l->next;
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ce = list_entry(l, struct mb_cache_entry, e_lru_list);
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if (ce->e_bdev == bdev) {
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list_move_tail(&ce->e_lru_list, &free_list);
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__mb_cache_entry_unhash(ce);
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list_del_init(&ce->e_lru_list);
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if (ce->e_used || ce->e_queued ||
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atomic_read(&ce->e_refcnt))
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continue;
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spin_unlock(&mb_cache_spinlock);
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/*
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* Prevent any find or get operation on the entry.
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*/
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hlist_bl_lock(ce->e_block_hash_p);
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hlist_bl_lock(ce->e_index_hash_p);
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/* Ignore if it is touched by a find/get */
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if (ce->e_used || ce->e_queued ||
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atomic_read(&ce->e_refcnt) ||
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!list_empty(&ce->e_lru_list)) {
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hlist_bl_unlock(ce->e_index_hash_p);
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hlist_bl_unlock(ce->e_block_hash_p);
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l = &mb_cache_lru_list;
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spin_lock(&mb_cache_spinlock);
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continue;
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}
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__mb_cache_entry_unhash_unlock(ce);
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mb_assert(!(ce->e_used || ce->e_queued ||
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atomic_read(&ce->e_refcnt)));
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list_add_tail(&ce->e_lru_list, &free_list);
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l = &mb_cache_lru_list;
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spin_lock(&mb_cache_spinlock);
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}
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}
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spin_unlock(&mb_cache_spinlock);
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list_for_each_safe(l, ltmp, &free_list) {
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__mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
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e_lru_list), GFP_KERNEL);
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list_for_each_entry_safe(ce, tmp, &free_list, e_lru_list) {
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__mb_cache_entry_forget(ce, GFP_KERNEL);
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}
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}
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@ -320,23 +447,27 @@ void
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mb_cache_destroy(struct mb_cache *cache)
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{
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LIST_HEAD(free_list);
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struct list_head *l, *ltmp;
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struct mb_cache_entry *ce, *tmp;
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spin_lock(&mb_cache_spinlock);
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list_for_each_safe(l, ltmp, &mb_cache_lru_list) {
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struct mb_cache_entry *ce =
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list_entry(l, struct mb_cache_entry, e_lru_list);
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if (ce->e_cache == cache) {
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list_for_each_entry_safe(ce, tmp, &mb_cache_lru_list, e_lru_list) {
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if (ce->e_cache == cache)
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list_move_tail(&ce->e_lru_list, &free_list);
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__mb_cache_entry_unhash(ce);
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}
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}
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list_del(&cache->c_cache_list);
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spin_unlock(&mb_cache_spinlock);
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list_for_each_safe(l, ltmp, &free_list) {
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__mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
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e_lru_list), GFP_KERNEL);
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list_for_each_entry_safe(ce, tmp, &free_list, e_lru_list) {
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list_del_init(&ce->e_lru_list);
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/*
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* Prevent any find or get operation on the entry.
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*/
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hlist_bl_lock(ce->e_block_hash_p);
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hlist_bl_lock(ce->e_index_hash_p);
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mb_assert(!(ce->e_used || ce->e_queued ||
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atomic_read(&ce->e_refcnt)));
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__mb_cache_entry_unhash_unlock(ce);
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__mb_cache_entry_forget(ce, GFP_KERNEL);
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}
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if (atomic_read(&cache->c_entry_count) > 0) {
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@ -345,8 +476,6 @@ mb_cache_destroy(struct mb_cache *cache)
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atomic_read(&cache->c_entry_count));
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}
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kmem_cache_destroy(cache->c_entry_cache);
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kfree(cache->c_index_hash);
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kfree(cache->c_block_hash);
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kfree(cache);
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@ -363,29 +492,59 @@ mb_cache_destroy(struct mb_cache *cache)
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struct mb_cache_entry *
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mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
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{
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struct mb_cache_entry *ce = NULL;
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struct mb_cache_entry *ce;
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if (atomic_read(&cache->c_entry_count) >= cache->c_max_entries) {
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struct list_head *l;
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l = &mb_cache_lru_list;
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spin_lock(&mb_cache_spinlock);
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if (!list_empty(&mb_cache_lru_list)) {
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ce = list_entry(mb_cache_lru_list.next,
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struct mb_cache_entry, e_lru_list);
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list_del_init(&ce->e_lru_list);
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__mb_cache_entry_unhash(ce);
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while (!list_is_last(l, &mb_cache_lru_list)) {
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l = l->next;
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ce = list_entry(l, struct mb_cache_entry, e_lru_list);
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if (ce->e_cache == cache) {
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list_del_init(&ce->e_lru_list);
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if (ce->e_used || ce->e_queued ||
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atomic_read(&ce->e_refcnt))
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continue;
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spin_unlock(&mb_cache_spinlock);
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/*
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* Prevent any find or get operation on the
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* entry.
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*/
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hlist_bl_lock(ce->e_block_hash_p);
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hlist_bl_lock(ce->e_index_hash_p);
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/* Ignore if it is touched by a find/get */
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if (ce->e_used || ce->e_queued ||
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atomic_read(&ce->e_refcnt) ||
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!list_empty(&ce->e_lru_list)) {
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hlist_bl_unlock(ce->e_index_hash_p);
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hlist_bl_unlock(ce->e_block_hash_p);
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l = &mb_cache_lru_list;
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spin_lock(&mb_cache_spinlock);
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continue;
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}
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mb_assert(list_empty(&ce->e_lru_list));
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mb_assert(!(ce->e_used || ce->e_queued ||
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atomic_read(&ce->e_refcnt)));
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__mb_cache_entry_unhash_unlock(ce);
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goto found;
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}
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}
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spin_unlock(&mb_cache_spinlock);
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}
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if (!ce) {
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ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
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if (!ce)
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return NULL;
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atomic_inc(&cache->c_entry_count);
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INIT_LIST_HEAD(&ce->e_lru_list);
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INIT_HLIST_BL_NODE(&ce->e_block_list);
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INIT_HLIST_BL_NODE(&ce->e_index.o_list);
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ce->e_cache = cache;
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ce->e_queued = 0;
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}
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ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
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if (!ce)
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return NULL;
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atomic_inc(&cache->c_entry_count);
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INIT_LIST_HEAD(&ce->e_lru_list);
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INIT_HLIST_BL_NODE(&ce->e_block_list);
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INIT_HLIST_BL_NODE(&ce->e_index.o_list);
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ce->e_cache = cache;
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ce->e_queued = 0;
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atomic_set(&ce->e_refcnt, 0);
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found:
|
||||
ce->e_block_hash_p = &cache->c_block_hash[0];
|
||||
ce->e_index_hash_p = &cache->c_index_hash[0];
|
||||
ce->e_used = 1 + MB_CACHE_WRITER;
|
||||
|
@ -414,7 +573,6 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
|
|||
struct mb_cache *cache = ce->e_cache;
|
||||
unsigned int bucket;
|
||||
struct hlist_bl_node *l;
|
||||
int error = -EBUSY;
|
||||
struct hlist_bl_head *block_hash_p;
|
||||
struct hlist_bl_head *index_hash_p;
|
||||
struct mb_cache_entry *lce;
|
||||
|
@ -423,26 +581,29 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
|
|||
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
|
||||
cache->c_bucket_bits);
|
||||
block_hash_p = &cache->c_block_hash[bucket];
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
hlist_bl_lock(block_hash_p);
|
||||
hlist_bl_for_each_entry(lce, l, block_hash_p, e_block_list) {
|
||||
if (lce->e_bdev == bdev && lce->e_block == block)
|
||||
goto out;
|
||||
if (lce->e_bdev == bdev && lce->e_block == block) {
|
||||
hlist_bl_unlock(block_hash_p);
|
||||
return -EBUSY;
|
||||
}
|
||||
}
|
||||
mb_assert(!__mb_cache_entry_is_block_hashed(ce));
|
||||
__mb_cache_entry_unhash(ce);
|
||||
__mb_cache_entry_unhash_block(ce);
|
||||
__mb_cache_entry_unhash_index(ce);
|
||||
ce->e_bdev = bdev;
|
||||
ce->e_block = block;
|
||||
ce->e_block_hash_p = block_hash_p;
|
||||
ce->e_index.o_key = key;
|
||||
hlist_bl_add_head(&ce->e_block_list, block_hash_p);
|
||||
hlist_bl_unlock(block_hash_p);
|
||||
bucket = hash_long(key, cache->c_bucket_bits);
|
||||
index_hash_p = &cache->c_index_hash[bucket];
|
||||
hlist_bl_lock(index_hash_p);
|
||||
ce->e_index_hash_p = index_hash_p;
|
||||
hlist_bl_add_head(&ce->e_index.o_list, index_hash_p);
|
||||
hlist_bl_add_head(&ce->e_block_list, block_hash_p);
|
||||
error = 0;
|
||||
out:
|
||||
spin_unlock(&mb_cache_spinlock);
|
||||
return error;
|
||||
hlist_bl_unlock(index_hash_p);
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
|
@ -456,24 +617,26 @@ out:
|
|||
void
|
||||
mb_cache_entry_release(struct mb_cache_entry *ce)
|
||||
{
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
__mb_cache_entry_release_unlock(ce);
|
||||
__mb_cache_entry_release(ce);
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* mb_cache_entry_free()
|
||||
*
|
||||
* This is equivalent to the sequence mb_cache_entry_takeout() --
|
||||
* mb_cache_entry_release().
|
||||
*/
|
||||
void
|
||||
mb_cache_entry_free(struct mb_cache_entry *ce)
|
||||
{
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
mb_assert(ce);
|
||||
mb_assert(list_empty(&ce->e_lru_list));
|
||||
__mb_cache_entry_unhash(ce);
|
||||
__mb_cache_entry_release_unlock(ce);
|
||||
hlist_bl_lock(ce->e_index_hash_p);
|
||||
__mb_cache_entry_unhash_index(ce);
|
||||
hlist_bl_unlock(ce->e_index_hash_p);
|
||||
hlist_bl_lock(ce->e_block_hash_p);
|
||||
__mb_cache_entry_unhash_block(ce);
|
||||
hlist_bl_unlock(ce->e_block_hash_p);
|
||||
__mb_cache_entry_release(ce);
|
||||
}
|
||||
|
||||
|
||||
|
@ -497,39 +660,48 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
|
|||
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
|
||||
cache->c_bucket_bits);
|
||||
block_hash_p = &cache->c_block_hash[bucket];
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
/* First serialize access to the block corresponding hash chain. */
|
||||
hlist_bl_lock(block_hash_p);
|
||||
hlist_bl_for_each_entry(ce, l, block_hash_p, e_block_list) {
|
||||
mb_assert(ce->e_block_hash_p == block_hash_p);
|
||||
if (ce->e_bdev == bdev && ce->e_block == block) {
|
||||
DEFINE_WAIT(wait);
|
||||
|
||||
if (!list_empty(&ce->e_lru_list))
|
||||
list_del_init(&ce->e_lru_list);
|
||||
|
||||
while (ce->e_used > 0) {
|
||||
ce->e_queued++;
|
||||
prepare_to_wait(&mb_cache_queue, &wait,
|
||||
TASK_UNINTERRUPTIBLE);
|
||||
spin_unlock(&mb_cache_spinlock);
|
||||
schedule();
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
ce->e_queued--;
|
||||
/*
|
||||
* Prevent a free from removing the entry.
|
||||
*/
|
||||
atomic_inc(&ce->e_refcnt);
|
||||
hlist_bl_unlock(block_hash_p);
|
||||
__spin_lock_mb_cache_entry(ce);
|
||||
atomic_dec(&ce->e_refcnt);
|
||||
if (ce->e_used > 0) {
|
||||
DEFINE_WAIT(wait);
|
||||
while (ce->e_used > 0) {
|
||||
ce->e_queued++;
|
||||
prepare_to_wait(&mb_cache_queue, &wait,
|
||||
TASK_UNINTERRUPTIBLE);
|
||||
__spin_unlock_mb_cache_entry(ce);
|
||||
schedule();
|
||||
__spin_lock_mb_cache_entry(ce);
|
||||
ce->e_queued--;
|
||||
}
|
||||
finish_wait(&mb_cache_queue, &wait);
|
||||
}
|
||||
finish_wait(&mb_cache_queue, &wait);
|
||||
ce->e_used += 1 + MB_CACHE_WRITER;
|
||||
__spin_unlock_mb_cache_entry(ce);
|
||||
|
||||
if (!list_empty(&ce->e_lru_list)) {
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
list_del_init(&ce->e_lru_list);
|
||||
spin_unlock(&mb_cache_spinlock);
|
||||
}
|
||||
if (!__mb_cache_entry_is_block_hashed(ce)) {
|
||||
__mb_cache_entry_release_unlock(ce);
|
||||
__mb_cache_entry_release(ce);
|
||||
return NULL;
|
||||
}
|
||||
goto cleanup;
|
||||
return ce;
|
||||
}
|
||||
}
|
||||
ce = NULL;
|
||||
|
||||
cleanup:
|
||||
spin_unlock(&mb_cache_spinlock);
|
||||
return ce;
|
||||
hlist_bl_unlock(block_hash_p);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
#if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0)
|
||||
|
@ -538,40 +710,53 @@ static struct mb_cache_entry *
|
|||
__mb_cache_entry_find(struct hlist_bl_node *l, struct hlist_bl_head *head,
|
||||
struct block_device *bdev, unsigned int key)
|
||||
{
|
||||
|
||||
/* The index hash chain is alredy acquire by caller. */
|
||||
while (l != NULL) {
|
||||
struct mb_cache_entry *ce =
|
||||
hlist_bl_entry(l, struct mb_cache_entry,
|
||||
e_index.o_list);
|
||||
mb_assert(ce->e_index_hash_p == head);
|
||||
if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
|
||||
DEFINE_WAIT(wait);
|
||||
|
||||
if (!list_empty(&ce->e_lru_list))
|
||||
list_del_init(&ce->e_lru_list);
|
||||
|
||||
/*
|
||||
* Prevent a free from removing the entry.
|
||||
*/
|
||||
atomic_inc(&ce->e_refcnt);
|
||||
hlist_bl_unlock(head);
|
||||
__spin_lock_mb_cache_entry(ce);
|
||||
atomic_dec(&ce->e_refcnt);
|
||||
ce->e_used++;
|
||||
/* Incrementing before holding the lock gives readers
|
||||
priority over writers. */
|
||||
ce->e_used++;
|
||||
while (ce->e_used >= MB_CACHE_WRITER) {
|
||||
ce->e_queued++;
|
||||
prepare_to_wait(&mb_cache_queue, &wait,
|
||||
TASK_UNINTERRUPTIBLE);
|
||||
spin_unlock(&mb_cache_spinlock);
|
||||
schedule();
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
ce->e_queued--;
|
||||
}
|
||||
finish_wait(&mb_cache_queue, &wait);
|
||||
if (ce->e_used >= MB_CACHE_WRITER) {
|
||||
DEFINE_WAIT(wait);
|
||||
|
||||
if (!__mb_cache_entry_is_block_hashed(ce)) {
|
||||
__mb_cache_entry_release_unlock(ce);
|
||||
while (ce->e_used >= MB_CACHE_WRITER) {
|
||||
ce->e_queued++;
|
||||
prepare_to_wait(&mb_cache_queue, &wait,
|
||||
TASK_UNINTERRUPTIBLE);
|
||||
__spin_unlock_mb_cache_entry(ce);
|
||||
schedule();
|
||||
__spin_lock_mb_cache_entry(ce);
|
||||
ce->e_queued--;
|
||||
}
|
||||
finish_wait(&mb_cache_queue, &wait);
|
||||
}
|
||||
__spin_unlock_mb_cache_entry(ce);
|
||||
if (!list_empty(&ce->e_lru_list)) {
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
list_del_init(&ce->e_lru_list);
|
||||
spin_unlock(&mb_cache_spinlock);
|
||||
}
|
||||
if (!__mb_cache_entry_is_block_hashed(ce)) {
|
||||
__mb_cache_entry_release(ce);
|
||||
return ERR_PTR(-EAGAIN);
|
||||
}
|
||||
return ce;
|
||||
}
|
||||
l = l->next;
|
||||
}
|
||||
hlist_bl_unlock(head);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
|
@ -598,12 +783,12 @@ mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev,
|
|||
struct hlist_bl_head *index_hash_p;
|
||||
|
||||
index_hash_p = &cache->c_index_hash[bucket];
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
hlist_bl_lock(index_hash_p);
|
||||
if (!hlist_bl_empty(index_hash_p)) {
|
||||
l = hlist_bl_first(index_hash_p);
|
||||
ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
|
||||
}
|
||||
spin_unlock(&mb_cache_spinlock);
|
||||
} else
|
||||
hlist_bl_unlock(index_hash_p);
|
||||
return ce;
|
||||
}
|
||||
|
||||
|
@ -638,11 +823,11 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev,
|
|||
|
||||
index_hash_p = &cache->c_index_hash[bucket];
|
||||
mb_assert(prev->e_index_hash_p == index_hash_p);
|
||||
spin_lock(&mb_cache_spinlock);
|
||||
hlist_bl_lock(index_hash_p);
|
||||
mb_assert(!hlist_bl_empty(index_hash_p));
|
||||
l = prev->e_index.o_list.next;
|
||||
ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
|
||||
__mb_cache_entry_release_unlock(prev);
|
||||
__mb_cache_entry_release(prev);
|
||||
return ce;
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue