34  * Multiple I/O requests may be using an L2 table cache entry at any given
35  * time.  That means an entry may be in use across several requests and
36  * reference counting is needed to free the entry at the correct time.  In
37  * particular, an entry evicted from the cache will only be freed once all
40  * An in-flight I/O request will hold a reference to a L2 table cache entry for
50  * table will be deleted in favor of the existing cache entry.
75     CachedL2Table *entry, *next_entry;  in qed_free_l2_cache()  local
77     QTAILQ_FOREACH_SAFE(entry, &l2_cache->entries, node, next_entry) {  in qed_free_l2_cache()
78         qemu_vfree(entry->table);  in qed_free_l2_cache()
79         g_free(entry);  in qed_free_l2_cache()
84  * Allocate an uninitialized entry from the cache
86  * The returned entry has a reference count of 1 and is owned by the caller.
87  * The caller must allocate the actual table field for this entry and it must
92     CachedL2Table *entry;  in qed_alloc_l2_cache_entry()  local
94     entry = g_malloc0(sizeof(*entry));  in qed_alloc_l2_cache_entry()
95     entry->ref++;  in qed_alloc_l2_cache_entry()
97     trace_qed_alloc_l2_cache_entry(l2_cache, entry);  in qed_alloc_l2_cache_entry()
99     return entry;  in qed_alloc_l2_cache_entry()
103  * Decrease an entry's reference count and free if necessary when the reference
108 void qed_unref_l2_cache_entry(CachedL2Table *entry)  in qed_unref_l2_cache_entry()  argument
110     if (!entry) {  in qed_unref_l2_cache_entry()
114     entry->ref--;  in qed_unref_l2_cache_entry()
115     trace_qed_unref_l2_cache_entry(entry, entry->ref);  in qed_unref_l2_cache_entry()
116     if (entry->ref == 0) {  in qed_unref_l2_cache_entry()
117         qemu_vfree(entry->table);  in qed_unref_l2_cache_entry()
118         g_free(entry);  in qed_unref_l2_cache_entry()
123  * Find an entry in the L2 cache.  This may return NULL and it's up to the
126  * For a cached entry, this function increases the reference count and returns
127  * the entry.
133     CachedL2Table *entry;  in qed_find_l2_cache_entry()  local
135     QTAILQ_FOREACH(entry, &l2_cache->entries, node) {  in qed_find_l2_cache_entry()
136         if (entry->offset == offset) {  in qed_find_l2_cache_entry()
137             trace_qed_find_l2_cache_entry(l2_cache, entry, offset, entry->ref);  in qed_find_l2_cache_entry()
138             entry->ref++;  in qed_find_l2_cache_entry()
139             return entry;  in qed_find_l2_cache_entry()
146  * Commit an L2 cache entry into the cache.  This is meant to be used as part of
147  * the process to satisfy a cache miss.  A caller would allocate an entry which
148  * is not actually in the L2 cache and then once the entry was valid and
149  * present on disk, the entry can be committed into the cache.
152  * called until the entry is present on disk and the L1 has been updated to
153  * point to the entry.
163     CachedL2Table *entry;  in qed_commit_l2_cache_entry()  local
165     entry = qed_find_l2_cache_entry(l2_cache, l2_table->offset);  in qed_commit_l2_cache_entry()
166     if (entry) {  in qed_commit_l2_cache_entry()
167         qed_unref_l2_cache_entry(entry);  in qed_commit_l2_cache_entry()
172     /* Evict an unused cache entry so we have space.  If all entries are in use  in qed_commit_l2_cache_entry()
177         QTAILQ_FOREACH_SAFE(entry, &l2_cache->entries, node, next) {  in qed_commit_l2_cache_entry()
178             if (entry->ref > 1) {  in qed_commit_l2_cache_entry()
182             QTAILQ_REMOVE(&l2_cache->entries, entry, node);  in qed_commit_l2_cache_entry()
184             qed_unref_l2_cache_entry(entry);  in qed_commit_l2_cache_entry()