regs-sdc.rar_multi media

#include <linux/spinlock.h> #include <linux/kthread.h> #include <linux/list.h> #include <linux/delay.h> #include <linux/freezer.h> #include <linux/bitmap.h> #include <xen/events.h> #include <xen/page.h> #include <xen/xen.h> #include <asm/xen/hypervisor.h> #include <asm/xen/hypercall.h> #include <xen/balloon.h> #include "common.h" /* * Maximum number of unused free pages to keep in the internal buffer. * Setting this to a value too low will reduce memory used in each backend, * but can have a performance penalty. * * A sane value is xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST, but can * be set to a lower value that might degrade performance on some intensive * IO workloads. */ static int xen_blkif_max_buffer_pages = 1024; module_param_named(max_buffer_pages, xen_blkif_max_buffer_pages, int, 0644); MODULE_PARM_DESC(max_buffer_pages, "Maximum number of free pages to keep in each block backend buffer"); /* * Maximum number of grants to map persistently in blkback. For maximum * performance this should be the total numbers of grants that can be used * to fill the ring, but since this might become too high, specially with * the use of indirect descriptors, we set it to a value that provides good * performance without using too much memory. * * When the list of persistent grants is full we clean it up using a LRU * algorithm. */ static int xen_blkif_max_pgrants = 1056; module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644); MODULE_PARM_DESC(max_persistent_grants, "Maximum number of grants to map persistently"); /* * The LRU mechanism to clean the lists of persistent grants needs to * be executed periodically. The time interval between consecutive executions * of the purge mechanism is set in ms. */ #define LRU_INTERVAL 100 /* * When the persistent grants list is full we will remove unused grants * from the list. The percent number of grants to be removed at each LRU * execution. */ #define LRU_PERCENT_CLEAN 5 /* Run-time switchable: /sys/module/blkback/parameters/ */ static unsigned int log_stats; module_param(log_stats, int, 0644); #define BLKBACK_INVALID_HANDLE (~0) /* Number of free pages to remove on each call to free_xenballooned_pages */ #define NUM_BATCH_FREE_PAGES 10 static inline int get_free_page(struct xen_blkif *blkif, struct page **page) { unsigned long flags; spin_lock_irqsave(&blkif->free_pages_lock, flags); if (list_empty(&blkif->free_pages)) { BUG_ON(blkif->free_pages_num != 0); spin_unlock_irqrestore(&blkif->free_pages_lock, flags); return alloc_xenballooned_pages(1, page, false); } BUG_ON(blkif->free_pages_num == 0); page[0] = list_first_entry(&blkif->free_pages, struct page, lru); list_del(&page[0]->lru); blkif->free_pages_num--; spin_unlock_irqrestore(&blkif->free_pages_lock, flags); return 0; } static inline void put_free_pages(struct xen_blkif *blkif, struct page **page, int num) { unsigned long flags; int i; spin_lock_irqsave(&blkif->free_pages_lock, flags); for (i = 0; i < num; i++) list_add(&page[i]->lru, &blkif->free_pages); blkif->free_pages_num += num; spin_unlock_irqrestore(&blkif->free_pages_lock, flags); } static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num) { /* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */ struct page *page[NUM_BATCH_FREE_PAGES]; unsigned int num_pages = 0; unsigned long flags; spin_lock_irqsave(&blkif->free_pages_lock, flags); while (blkif->free_pages_num > num) { BUG_ON(list_empty(&blkif->free_pages)); page[num_pages] = list_first_entry(&blkif->free_pages, struct page, lru); list_del(&page[num_pages]->lru); blkif->free_pages_num--; if (++num_pages == NUM_BATCH_FREE_PAGES) { spin_unlock_irqrestore(&blkif->free_pages_lock, flags); free_xenballooned_pages(num_pages, page); spin_lock_irqsave(&blkif->free_pages_lock, flags); num_pages = 0; } } spin_unlock_irqrestore(&blkif->free_pages_lock, flags); if (num_pages != 0) free_xenballooned_pages(num_pages, page); } #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page))) static int do_block_io_op(struct xen_blkif *blkif); static int dispatch_rw_block_io(struct xen_blkif *blkif, struct blkif_request *req, struct pending_req *pending_req); static void make_response(struct xen_blkif *blkif, u64 id, unsigned short op, int st); #define foreach_grant_safe(pos, n, rbtree, node) \ for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \ (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \ &(pos)->node != NULL; \ (pos) = container_of(n, typeof(*(pos)), node), \ (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL) /* * We don't need locking around the persistent grant helpers * because blkback uses a single-thread for each backed, so we * can be sure that this functions will never be called recursively. * * The only exception to that is put_persistent_grant, that can be called * from interrupt context (by xen_blkbk_unmap), so we have to use atomic * bit operations to modify the flags of a persistent grant and to count * the number of used grants. */ static int add_persistent_gnt(struct xen_blkif *blkif, struct persistent_gnt *persistent_gnt) { struct rb_node **new = NULL, *parent = NULL; struct persistent_gnt *this; if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) { if (!blkif->vbd.overflow_max_grants) blkif->vbd.overflow_max_grants = 1; return -EBUSY; } /* Figure out where to put new node */ new = &blkif->persistent_gnts.rb_node; while (*new) { this = container_of(*new, struct persistent_gnt, node); parent = *new; if (persistent_gnt->gnt < this->gnt) new = &((*new)->rb_left); else if (persistent_gnt->gnt > this->gnt) new = &((*new)->rb_right); else { pr_alert_ratelimited(DRV_PFX " trying to add a gref that's already in the tree\n"); return -EINVAL; } } bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE); set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); /* Add new node and rebalance tree. */ rb_link_node(&(persistent_gnt->node), parent, new); rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts); blkif->persistent_gnt_c++; atomic_inc(&blkif->persistent_gnt_in_use); return 0; } static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif, grant_ref_t gref) { struct persistent_gnt *data; struct rb_node *node = NULL; node = blkif->persistent_gnts.rb_node; while (node) { data = container_of(node, struct persistent_gnt, node); if (gref < data->gnt) node = node->rb_left; else if (gref > data->gnt) node = node->rb_right; else { if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) { pr_alert_ratelimited(DRV_PFX " requesting a grant already in use\n"); return NULL; } set_bit(PERSISTENT_GNT_ACTIVE, data->flags); atomic_inc(&blkif->persistent_gnt_in_use); return data; } } return NULL; } static void put_persistent_gnt(struct xen_blkif *blkif, struct persistent_gnt *persistent_gnt) { if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) pr_alert_ratelimited(DRV_PFX " freeing a grant already unused"); set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); atomic_dec(&blkif->persistent_gnt_in_use); } static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root, unsigned int num) { struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; struct persistent_gnt *persistent_gnt; struct rb_node *n; int ret = 0; int segs_to_unmap = 0; foreach_grant_safe(persistent_gnt, n, root, node) { BUG_ON(persistent_gnt->handle == BLKBACK_INVALID_HANDLE); gnttab_set_unmap