zvol: reduce linear list search
Use kernel ida to generate minor number, and use hash table to find zvol with name. Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
This commit is contained in:
Chunwei Chen
parent
57ddcda164
commit
d45e010dce
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@ -63,6 +63,11 @@ static kmutex_t zvol_state_lock;
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static list_t zvol_state_list;
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void *zvol_tag = "zvol_tag";
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#define ZVOL_HT_SIZE 1024
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static struct hlist_head *zvol_htable;
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#define ZVOL_HT_HEAD(hash) (&zvol_htable[(hash) & (ZVOL_HT_SIZE-1)])
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static DEFINE_IDA(zvol_ida);
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/*
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* The in-core state of each volume.
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*/
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@ -81,6 +86,8 @@ typedef struct zvol_state {
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struct gendisk *zv_disk; /* generic disk */
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struct request_queue *zv_queue; /* request queue */
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list_node_t zv_next; /* next zvol_state_t linkage */
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uint64_t zv_hash; /* name hash */
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struct hlist_node zv_hlink; /* hash link */
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} zvol_state_t;
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typedef enum {
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@ -102,30 +109,17 @@ typedef struct {
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#define ZVOL_RDONLY 0x1
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/*
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* Find the next available range of ZVOL_MINORS minor numbers. The
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* zvol_state_list is kept in ascending minor order so we simply need
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* to scan the list for the first gap in the sequence. This allows us
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* to recycle minor number as devices are created and removed.
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*/
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static int
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zvol_find_minor(unsigned *minor)
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static uint64_t
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zvol_name_hash(const char *name)
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{
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zvol_state_t *zv;
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*minor = 0;
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ASSERT(MUTEX_HELD(&zvol_state_lock));
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for (zv = list_head(&zvol_state_list); zv != NULL;
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zv = list_next(&zvol_state_list, zv), *minor += ZVOL_MINORS) {
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if (MINOR(zv->zv_dev) != MINOR(*minor))
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break;
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int i;
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uint64_t crc = -1ULL;
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uint8_t *p = (uint8_t *)name;
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ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
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for (i = 0; i < MAXNAMELEN - 1 && *p; i++, p++) {
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crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (*p)) & 0xFF];
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}
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/* All minors are in use */
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if (*minor >= (1 << MINORBITS))
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return (SET_ERROR(ENXIO));
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return (0);
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return (crc);
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}
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/*
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@ -146,22 +140,32 @@ zvol_find_by_dev(dev_t dev)
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return (NULL);
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}
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/*
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* Find a zvol_state_t given the name and hash generated by zvol_name_hash.
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*/
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static zvol_state_t *
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zvol_find_by_name_hash(const char *name, uint64_t hash)
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{
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zvol_state_t *zv;
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struct hlist_node *p;
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ASSERT(MUTEX_HELD(&zvol_state_lock));
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hlist_for_each(p, ZVOL_HT_HEAD(hash)) {
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zv = hlist_entry(p, zvol_state_t, zv_hlink);
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if (zv->zv_hash == hash &&
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strncmp(zv->zv_name, name, MAXNAMELEN) == 0)
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return (zv);
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}
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return (NULL);
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}
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/*
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* Find a zvol_state_t given the name provided at zvol_alloc() time.
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*/
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static zvol_state_t *
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zvol_find_by_name(const char *name)
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{
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zvol_state_t *zv;
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ASSERT(MUTEX_HELD(&zvol_state_lock));
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for (zv = list_head(&zvol_state_list); zv != NULL;
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zv = list_next(&zvol_state_list, zv)) {
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if (strncmp(zv->zv_name, name, MAXNAMELEN) == 0)
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return (zv);
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}
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return (NULL);
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return (zvol_find_by_name_hash(name, zvol_name_hash(name)));
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}
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@ -921,32 +925,26 @@ zvol_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
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}
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/*
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* The zvol_state_t's are inserted in increasing MINOR(dev_t) order.
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* The zvol_state_t's are inserted into zvol_state_list and zvol_htable.
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*/
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static void
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zvol_insert(zvol_state_t *zv_insert)
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zvol_insert(zvol_state_t *zv)
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{
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zvol_state_t *zv = NULL;
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ASSERT(MUTEX_HELD(&zvol_state_lock));
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ASSERT3U(MINOR(zv_insert->zv_dev) & ZVOL_MINOR_MASK, ==, 0);
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for (zv = list_head(&zvol_state_list); zv != NULL;
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zv = list_next(&zvol_state_list, zv)) {
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if (MINOR(zv->zv_dev) > MINOR(zv_insert->zv_dev))
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break;
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}
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list_insert_before(&zvol_state_list, zv, zv_insert);
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ASSERT3U(MINOR(zv->zv_dev) & ZVOL_MINOR_MASK, ==, 0);
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list_insert_head(&zvol_state_list, zv);
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hlist_add_head(&zv->zv_hlink, ZVOL_HT_HEAD(zv->zv_hash));
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}
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/*
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* Simply remove the zvol from to list of zvols.
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*/
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static void
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zvol_remove(zvol_state_t *zv_remove)
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zvol_remove(zvol_state_t *zv)
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{
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ASSERT(MUTEX_HELD(&zvol_state_lock));
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list_remove(&zvol_state_list, zv_remove);
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list_remove(&zvol_state_list, zv);
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hlist_del(&zv->zv_hlink);
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}
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static int
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@ -1334,6 +1332,7 @@ zvol_free(zvol_state_t *zv)
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blk_cleanup_queue(zv->zv_queue);
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put_disk(zv->zv_disk);
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ida_simple_remove(&zvol_ida, MINOR(zv->zv_dev) >> ZVOL_MINOR_BITS);
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kmem_free(zv, sizeof (zvol_state_t));
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}
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@ -1352,10 +1351,17 @@ zvol_create_minor_impl(const char *name)
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uint64_t len;
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unsigned minor = 0;
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int error = 0;
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int idx;
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uint64_t hash = zvol_name_hash(name);
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idx = ida_simple_get(&zvol_ida, 0, 0, kmem_flags_convert(KM_SLEEP));
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if (idx < 0)
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return (SET_ERROR(-idx));
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minor = idx << ZVOL_MINOR_BITS;
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mutex_enter(&zvol_state_lock);
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zv = zvol_find_by_name(name);
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zv = zvol_find_by_name_hash(name, hash);
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if (zv) {
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error = SET_ERROR(EEXIST);
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goto out;
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@ -1375,15 +1381,12 @@ zvol_create_minor_impl(const char *name)
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if (error)
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goto out_dmu_objset_disown;
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error = zvol_find_minor(&minor);
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if (error)
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goto out_dmu_objset_disown;
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zv = zvol_alloc(MKDEV(zvol_major, minor), name);
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if (zv == NULL) {
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error = SET_ERROR(EAGAIN);
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goto out_dmu_objset_disown;
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}
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zv->zv_hash = hash;
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if (dmu_objset_is_snapshot(os))
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zv->zv_flags |= ZVOL_RDONLY;
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@ -1449,6 +1452,7 @@ out:
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add_disk(zv->zv_disk);
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} else {
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mutex_exit(&zvol_state_lock);
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ida_simple_remove(&zvol_ida, idx);
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}
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return (SET_ERROR(error));
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@ -1933,16 +1937,25 @@ zvol_rename_minors(spa_t *spa, const char *name1, const char *name2,
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int
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zvol_init(void)
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{
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int error;
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int i, error;
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list_create(&zvol_state_list, sizeof (zvol_state_t),
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offsetof(zvol_state_t, zv_next));
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mutex_init(&zvol_state_lock, NULL, MUTEX_DEFAULT, NULL);
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zvol_htable = kmem_alloc(ZVOL_HT_SIZE * sizeof (struct hlist_head),
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KM_SLEEP);
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if (!zvol_htable) {
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error = ENOMEM;
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goto out;
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}
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for (i = 0; i < ZVOL_HT_SIZE; i++)
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INIT_HLIST_HEAD(&zvol_htable[i]);
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error = register_blkdev(zvol_major, ZVOL_DRIVER);
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if (error) {
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printk(KERN_INFO "ZFS: register_blkdev() failed %d\n", error);
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goto out;
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goto out_free;
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}
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blk_register_region(MKDEV(zvol_major, 0), 1UL << MINORBITS,
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@ -1950,6 +1963,8 @@ zvol_init(void)
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return (0);
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out_free:
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kmem_free(zvol_htable, ZVOL_HT_SIZE * sizeof (struct hlist_head));
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out:
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mutex_destroy(&zvol_state_lock);
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list_destroy(&zvol_state_list);
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@ -1964,6 +1979,7 @@ zvol_fini(void)
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blk_unregister_region(MKDEV(zvol_major, 0), 1UL << MINORBITS);
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unregister_blkdev(zvol_major, ZVOL_DRIVER);
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kmem_free(zvol_htable, ZVOL_HT_SIZE * sizeof (struct hlist_head));
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list_destroy(&zvol_state_list);
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mutex_destroy(&zvol_state_lock);
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