![Roger Pau Monne](/assets/img/avatar_default.png)
Move the code that frees persistent grants from the red-black tree to a function. This will make it easier for other consumers to move this to a common place. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
1132 lines
30 KiB
C
1132 lines
30 KiB
C
/******************************************************************************
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*
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* Back-end of the driver for virtual block devices. This portion of the
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* driver exports a 'unified' block-device interface that can be accessed
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* by any operating system that implements a compatible front end. A
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* reference front-end implementation can be found in:
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* drivers/block/xen-blkfront.c
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*
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* Copyright (c) 2003-2004, Keir Fraser & Steve Hand
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* Copyright (c) 2005, Christopher Clark
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include <linux/spinlock.h>
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#include <linux/kthread.h>
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#include <linux/list.h>
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#include <linux/delay.h>
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#include <linux/freezer.h>
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#include <linux/bitmap.h>
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#include <xen/events.h>
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#include <xen/page.h>
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#include <xen/xen.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/xen/hypercall.h>
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#include "common.h"
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/*
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* These are rather arbitrary. They are fairly large because adjacent requests
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* pulled from a communication ring are quite likely to end up being part of
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* the same scatter/gather request at the disc.
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*
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* ** TRY INCREASING 'xen_blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW **
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*
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* This will increase the chances of being able to write whole tracks.
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* 64 should be enough to keep us competitive with Linux.
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*/
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static int xen_blkif_reqs = 64;
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module_param_named(reqs, xen_blkif_reqs, int, 0);
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MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate");
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/* Run-time switchable: /sys/module/blkback/parameters/ */
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static unsigned int log_stats;
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module_param(log_stats, int, 0644);
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/*
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* Each outstanding request that we've passed to the lower device layers has a
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* 'pending_req' allocated to it. Each buffer_head that completes decrements
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* the pendcnt towards zero. When it hits zero, the specified domain has a
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* response queued for it, with the saved 'id' passed back.
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*/
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struct pending_req {
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struct xen_blkif *blkif;
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u64 id;
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int nr_pages;
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atomic_t pendcnt;
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unsigned short operation;
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int status;
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struct list_head free_list;
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DECLARE_BITMAP(unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
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};
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#define BLKBACK_INVALID_HANDLE (~0)
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struct xen_blkbk {
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struct pending_req *pending_reqs;
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/* List of all 'pending_req' available */
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struct list_head pending_free;
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/* And its spinlock. */
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spinlock_t pending_free_lock;
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wait_queue_head_t pending_free_wq;
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/* The list of all pages that are available. */
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struct page **pending_pages;
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/* And the grant handles that are available. */
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grant_handle_t *pending_grant_handles;
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};
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static struct xen_blkbk *blkbk;
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/*
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* Maximum number of grant pages that can be mapped in blkback.
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* BLKIF_MAX_SEGMENTS_PER_REQUEST * RING_SIZE is the maximum number of
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* pages that blkback will persistently map.
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* Currently, this is:
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* RING_SIZE = 32 (for all known ring types)
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* BLKIF_MAX_SEGMENTS_PER_REQUEST = 11
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* sizeof(struct persistent_gnt) = 48
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* So the maximum memory used to store the grants is:
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* 32 * 11 * 48 = 16896 bytes
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*/
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static inline unsigned int max_mapped_grant_pages(enum blkif_protocol protocol)
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{
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switch (protocol) {
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case BLKIF_PROTOCOL_NATIVE:
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return __CONST_RING_SIZE(blkif, PAGE_SIZE) *
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BLKIF_MAX_SEGMENTS_PER_REQUEST;
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case BLKIF_PROTOCOL_X86_32:
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return __CONST_RING_SIZE(blkif_x86_32, PAGE_SIZE) *
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BLKIF_MAX_SEGMENTS_PER_REQUEST;
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case BLKIF_PROTOCOL_X86_64:
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return __CONST_RING_SIZE(blkif_x86_64, PAGE_SIZE) *
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BLKIF_MAX_SEGMENTS_PER_REQUEST;
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default:
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BUG();
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}
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return 0;
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}
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/*
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* Little helpful macro to figure out the index and virtual address of the
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* pending_pages[..]. For each 'pending_req' we have have up to
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* BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through
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* 10 and would index in the pending_pages[..].
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*/
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static inline int vaddr_pagenr(struct pending_req *req, int seg)
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{
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return (req - blkbk->pending_reqs) *
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BLKIF_MAX_SEGMENTS_PER_REQUEST + seg;
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}
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#define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)]
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static inline unsigned long vaddr(struct pending_req *req, int seg)
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{
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unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg));
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return (unsigned long)pfn_to_kaddr(pfn);
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}
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#define pending_handle(_req, _seg) \
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(blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)])
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static int do_block_io_op(struct xen_blkif *blkif);
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static int dispatch_rw_block_io(struct xen_blkif *blkif,
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struct blkif_request *req,
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struct pending_req *pending_req);
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static void make_response(struct xen_blkif *blkif, u64 id,
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unsigned short op, int st);
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#define foreach_grant(pos, rbtree, node) \
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for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node); \
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&(pos)->node != NULL; \
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(pos) = container_of(rb_next(&(pos)->node), typeof(*(pos)), node))
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static void add_persistent_gnt(struct rb_root *root,
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struct persistent_gnt *persistent_gnt)
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{
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struct rb_node **new = &(root->rb_node), *parent = NULL;
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struct persistent_gnt *this;
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/* Figure out where to put new node */
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while (*new) {
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this = container_of(*new, struct persistent_gnt, node);
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parent = *new;
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if (persistent_gnt->gnt < this->gnt)
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new = &((*new)->rb_left);
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else if (persistent_gnt->gnt > this->gnt)
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new = &((*new)->rb_right);
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else {
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pr_alert(DRV_PFX " trying to add a gref that's already in the tree\n");
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BUG();
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}
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}
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/* Add new node and rebalance tree. */
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rb_link_node(&(persistent_gnt->node), parent, new);
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rb_insert_color(&(persistent_gnt->node), root);
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}
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static struct persistent_gnt *get_persistent_gnt(struct rb_root *root,
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grant_ref_t gref)
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{
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struct persistent_gnt *data;
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struct rb_node *node = root->rb_node;
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while (node) {
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data = container_of(node, struct persistent_gnt, node);
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if (gref < data->gnt)
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node = node->rb_left;
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else if (gref > data->gnt)
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node = node->rb_right;
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else
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return data;
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}
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return NULL;
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}
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static void free_persistent_gnts(struct rb_root *root, unsigned int num)
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{
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struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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struct persistent_gnt *persistent_gnt;
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int ret = 0;
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int segs_to_unmap = 0;
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foreach_grant(persistent_gnt, root, node) {
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BUG_ON(persistent_gnt->handle ==
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BLKBACK_INVALID_HANDLE);
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gnttab_set_unmap_op(&unmap[segs_to_unmap],
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(unsigned long) pfn_to_kaddr(page_to_pfn(
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persistent_gnt->page)),
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GNTMAP_host_map,
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persistent_gnt->handle);
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pages[segs_to_unmap] = persistent_gnt->page;
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rb_erase(&persistent_gnt->node, root);
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kfree(persistent_gnt);
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num--;
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if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
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!rb_next(&persistent_gnt->node)) {
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ret = gnttab_unmap_refs(unmap, NULL, pages,
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segs_to_unmap);
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BUG_ON(ret);
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segs_to_unmap = 0;
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}
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}
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BUG_ON(num != 0);
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}
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/*
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* Retrieve from the 'pending_reqs' a free pending_req structure to be used.
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*/
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static struct pending_req *alloc_req(void)
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{
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struct pending_req *req = NULL;
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unsigned long flags;
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spin_lock_irqsave(&blkbk->pending_free_lock, flags);
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if (!list_empty(&blkbk->pending_free)) {
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req = list_entry(blkbk->pending_free.next, struct pending_req,
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free_list);
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list_del(&req->free_list);
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}
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spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
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return req;
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}
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/*
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* Return the 'pending_req' structure back to the freepool. We also
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* wake up the thread if it was waiting for a free page.
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*/
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static void free_req(struct pending_req *req)
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{
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unsigned long flags;
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int was_empty;
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spin_lock_irqsave(&blkbk->pending_free_lock, flags);
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was_empty = list_empty(&blkbk->pending_free);
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list_add(&req->free_list, &blkbk->pending_free);
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spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
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if (was_empty)
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wake_up(&blkbk->pending_free_wq);
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}
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/*
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* Routines for managing virtual block devices (vbds).
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*/
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static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
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int operation)
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{
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struct xen_vbd *vbd = &blkif->vbd;
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int rc = -EACCES;
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if ((operation != READ) && vbd->readonly)
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goto out;
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if (likely(req->nr_sects)) {
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blkif_sector_t end = req->sector_number + req->nr_sects;
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if (unlikely(end < req->sector_number))
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goto out;
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if (unlikely(end > vbd_sz(vbd)))
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goto out;
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}
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req->dev = vbd->pdevice;
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req->bdev = vbd->bdev;
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rc = 0;
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out:
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return rc;
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}
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static void xen_vbd_resize(struct xen_blkif *blkif)
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{
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struct xen_vbd *vbd = &blkif->vbd;
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struct xenbus_transaction xbt;
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int err;
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struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be);
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unsigned long long new_size = vbd_sz(vbd);
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pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n",
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blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
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pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size);
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vbd->size = new_size;
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again:
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err = xenbus_transaction_start(&xbt);
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if (err) {
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pr_warn(DRV_PFX "Error starting transaction");
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return;
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}
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err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
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(unsigned long long)vbd_sz(vbd));
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if (err) {
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pr_warn(DRV_PFX "Error writing new size");
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goto abort;
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}
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/*
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* Write the current state; we will use this to synchronize
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* the front-end. If the current state is "connected" the
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* front-end will get the new size information online.
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*/
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err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
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if (err) {
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pr_warn(DRV_PFX "Error writing the state");
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goto abort;
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}
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err = xenbus_transaction_end(xbt, 0);
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if (err == -EAGAIN)
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goto again;
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if (err)
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pr_warn(DRV_PFX "Error ending transaction");
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return;
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abort:
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xenbus_transaction_end(xbt, 1);
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}
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/*
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* Notification from the guest OS.
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*/
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static void blkif_notify_work(struct xen_blkif *blkif)
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{
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blkif->waiting_reqs = 1;
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wake_up(&blkif->wq);
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}
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irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
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{
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blkif_notify_work(dev_id);
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return IRQ_HANDLED;
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}
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/*
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* SCHEDULER FUNCTIONS
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*/
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static void print_stats(struct xen_blkif *blkif)
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{
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pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d"
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" | ds %4d\n",
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current->comm, blkif->st_oo_req,
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blkif->st_rd_req, blkif->st_wr_req,
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blkif->st_f_req, blkif->st_ds_req);
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blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
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blkif->st_rd_req = 0;
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blkif->st_wr_req = 0;
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blkif->st_oo_req = 0;
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blkif->st_ds_req = 0;
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}
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int xen_blkif_schedule(void *arg)
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{
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struct xen_blkif *blkif = arg;
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struct xen_vbd *vbd = &blkif->vbd;
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xen_blkif_get(blkif);
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while (!kthread_should_stop()) {
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if (try_to_freeze())
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continue;
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if (unlikely(vbd->size != vbd_sz(vbd)))
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xen_vbd_resize(blkif);
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wait_event_interruptible(
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blkif->wq,
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blkif->waiting_reqs || kthread_should_stop());
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wait_event_interruptible(
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blkbk->pending_free_wq,
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!list_empty(&blkbk->pending_free) ||
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kthread_should_stop());
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blkif->waiting_reqs = 0;
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smp_mb(); /* clear flag *before* checking for work */
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if (do_block_io_op(blkif))
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blkif->waiting_reqs = 1;
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if (log_stats && time_after(jiffies, blkif->st_print))
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print_stats(blkif);
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}
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|
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/* Free all persistent grant pages */
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if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
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free_persistent_gnts(&blkif->persistent_gnts,
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blkif->persistent_gnt_c);
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|
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BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
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blkif->persistent_gnt_c = 0;
|
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|
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if (log_stats)
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print_stats(blkif);
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|
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blkif->xenblkd = NULL;
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xen_blkif_put(blkif);
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|
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return 0;
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}
|
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|
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struct seg_buf {
|
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unsigned long buf;
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unsigned int nsec;
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};
|
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/*
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* Unmap the grant references, and also remove the M2P over-rides
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* used in the 'pending_req'.
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*/
|
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static void xen_blkbk_unmap(struct pending_req *req)
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{
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struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
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struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
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unsigned int i, invcount = 0;
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grant_handle_t handle;
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int ret;
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|
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for (i = 0; i < req->nr_pages; i++) {
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if (!test_bit(i, req->unmap_seg))
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continue;
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handle = pending_handle(req, i);
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if (handle == BLKBACK_INVALID_HANDLE)
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continue;
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gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
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GNTMAP_host_map, handle);
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pending_handle(req, i) = BLKBACK_INVALID_HANDLE;
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pages[invcount] = virt_to_page(vaddr(req, i));
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invcount++;
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}
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ret = gnttab_unmap_refs(unmap, NULL, pages, invcount);
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BUG_ON(ret);
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}
|
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|
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static int xen_blkbk_map(struct blkif_request *req,
|
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struct pending_req *pending_req,
|
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struct seg_buf seg[],
|
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struct page *pages[])
|
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{
|
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struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
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struct persistent_gnt *persistent_gnts[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
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struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
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struct persistent_gnt *persistent_gnt = NULL;
|
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struct xen_blkif *blkif = pending_req->blkif;
|
|
phys_addr_t addr = 0;
|
|
int i, j;
|
|
bool new_map;
|
|
int nseg = req->u.rw.nr_segments;
|
|
int segs_to_map = 0;
|
|
int ret = 0;
|
|
int use_persistent_gnts;
|
|
|
|
use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
|
|
|
|
BUG_ON(blkif->persistent_gnt_c >
|
|
max_mapped_grant_pages(pending_req->blkif->blk_protocol));
|
|
|
|
/*
|
|
* Fill out preq.nr_sects with proper amount of sectors, and setup
|
|
* assign map[..] with the PFN of the page in our domain with the
|
|
* corresponding grant reference for each page.
|
|
*/
|
|
for (i = 0; i < nseg; i++) {
|
|
uint32_t flags;
|
|
|
|
if (use_persistent_gnts)
|
|
persistent_gnt = get_persistent_gnt(
|
|
&blkif->persistent_gnts,
|
|
req->u.rw.seg[i].gref);
|
|
|
|
if (persistent_gnt) {
|
|
/*
|
|
* We are using persistent grants and
|
|
* the grant is already mapped
|
|
*/
|
|
new_map = false;
|
|
} else if (use_persistent_gnts &&
|
|
blkif->persistent_gnt_c <
|
|
max_mapped_grant_pages(blkif->blk_protocol)) {
|
|
/*
|
|
* We are using persistent grants, the grant is
|
|
* not mapped but we have room for it
|
|
*/
|
|
new_map = true;
|
|
persistent_gnt = kmalloc(
|
|
sizeof(struct persistent_gnt),
|
|
GFP_KERNEL);
|
|
if (!persistent_gnt)
|
|
return -ENOMEM;
|
|
persistent_gnt->page = alloc_page(GFP_KERNEL);
|
|
if (!persistent_gnt->page) {
|
|
kfree(persistent_gnt);
|
|
return -ENOMEM;
|
|
}
|
|
persistent_gnt->gnt = req->u.rw.seg[i].gref;
|
|
persistent_gnt->handle = BLKBACK_INVALID_HANDLE;
|
|
|
|
pages_to_gnt[segs_to_map] =
|
|
persistent_gnt->page;
|
|
addr = (unsigned long) pfn_to_kaddr(
|
|
page_to_pfn(persistent_gnt->page));
|
|
|
|
add_persistent_gnt(&blkif->persistent_gnts,
|
|
persistent_gnt);
|
|
blkif->persistent_gnt_c++;
|
|
pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
|
|
persistent_gnt->gnt, blkif->persistent_gnt_c,
|
|
max_mapped_grant_pages(blkif->blk_protocol));
|
|
} else {
|
|
/*
|
|
* We are either using persistent grants and
|
|
* hit the maximum limit of grants mapped,
|
|
* or we are not using persistent grants.
|
|
*/
|
|
if (use_persistent_gnts &&
|
|
!blkif->vbd.overflow_max_grants) {
|
|
blkif->vbd.overflow_max_grants = 1;
|
|
pr_alert(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n",
|
|
blkif->domid, blkif->vbd.handle);
|
|
}
|
|
new_map = true;
|
|
pages[i] = blkbk->pending_page(pending_req, i);
|
|
addr = vaddr(pending_req, i);
|
|
pages_to_gnt[segs_to_map] =
|
|
blkbk->pending_page(pending_req, i);
|
|
}
|
|
|
|
if (persistent_gnt) {
|
|
pages[i] = persistent_gnt->page;
|
|
persistent_gnts[i] = persistent_gnt;
|
|
} else {
|
|
persistent_gnts[i] = NULL;
|
|
}
|
|
|
|
if (new_map) {
|
|
flags = GNTMAP_host_map;
|
|
if (!persistent_gnt &&
|
|
(pending_req->operation != BLKIF_OP_READ))
|
|
flags |= GNTMAP_readonly;
|
|
gnttab_set_map_op(&map[segs_to_map++], addr,
|
|
flags, req->u.rw.seg[i].gref,
|
|
blkif->domid);
|
|
}
|
|
}
|
|
|
|
if (segs_to_map) {
|
|
ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
|
|
BUG_ON(ret);
|
|
}
|
|
|
|
/*
|
|
* Now swizzle the MFN in our domain with the MFN from the other domain
|
|
* so that when we access vaddr(pending_req,i) it has the contents of
|
|
* the page from the other domain.
|
|
*/
|
|
bitmap_zero(pending_req->unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
|
|
for (i = 0, j = 0; i < nseg; i++) {
|
|
if (!persistent_gnts[i] ||
|
|
persistent_gnts[i]->handle == BLKBACK_INVALID_HANDLE) {
|
|
/* This is a newly mapped grant */
|
|
BUG_ON(j >= segs_to_map);
|
|
if (unlikely(map[j].status != 0)) {
|
|
pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
|
|
map[j].handle = BLKBACK_INVALID_HANDLE;
|
|
ret |= 1;
|
|
if (persistent_gnts[i]) {
|
|
rb_erase(&persistent_gnts[i]->node,
|
|
&blkif->persistent_gnts);
|
|
blkif->persistent_gnt_c--;
|
|
kfree(persistent_gnts[i]);
|
|
persistent_gnts[i] = NULL;
|
|
}
|
|
}
|
|
}
|
|
if (persistent_gnts[i]) {
|
|
if (persistent_gnts[i]->handle ==
|
|
BLKBACK_INVALID_HANDLE) {
|
|
/*
|
|
* If this is a new persistent grant
|
|
* save the handler
|
|
*/
|
|
persistent_gnts[i]->handle = map[j].handle;
|
|
persistent_gnts[i]->dev_bus_addr =
|
|
map[j++].dev_bus_addr;
|
|
}
|
|
pending_handle(pending_req, i) =
|
|
persistent_gnts[i]->handle;
|
|
|
|
if (ret)
|
|
continue;
|
|
|
|
seg[i].buf = persistent_gnts[i]->dev_bus_addr |
|
|
(req->u.rw.seg[i].first_sect << 9);
|
|
} else {
|
|
pending_handle(pending_req, i) = map[j].handle;
|
|
bitmap_set(pending_req->unmap_seg, i, 1);
|
|
|
|
if (ret) {
|
|
j++;
|
|
continue;
|
|
}
|
|
|
|
seg[i].buf = map[j++].dev_bus_addr |
|
|
(req->u.rw.seg[i].first_sect << 9);
|
|
}
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int dispatch_discard_io(struct xen_blkif *blkif,
|
|
struct blkif_request *req)
|
|
{
|
|
int err = 0;
|
|
int status = BLKIF_RSP_OKAY;
|
|
struct block_device *bdev = blkif->vbd.bdev;
|
|
unsigned long secure;
|
|
|
|
blkif->st_ds_req++;
|
|
|
|
xen_blkif_get(blkif);
|
|
secure = (blkif->vbd.discard_secure &&
|
|
(req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
|
|
BLKDEV_DISCARD_SECURE : 0;
|
|
|
|
err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
|
|
req->u.discard.nr_sectors,
|
|
GFP_KERNEL, secure);
|
|
|
|
if (err == -EOPNOTSUPP) {
|
|
pr_debug(DRV_PFX "discard op failed, not supported\n");
|
|
status = BLKIF_RSP_EOPNOTSUPP;
|
|
} else if (err)
|
|
status = BLKIF_RSP_ERROR;
|
|
|
|
make_response(blkif, req->u.discard.id, req->operation, status);
|
|
xen_blkif_put(blkif);
|
|
return err;
|
|
}
|
|
|
|
static void xen_blk_drain_io(struct xen_blkif *blkif)
|
|
{
|
|
atomic_set(&blkif->drain, 1);
|
|
do {
|
|
/* The initial value is one, and one refcnt taken at the
|
|
* start of the xen_blkif_schedule thread. */
|
|
if (atomic_read(&blkif->refcnt) <= 2)
|
|
break;
|
|
wait_for_completion_interruptible_timeout(
|
|
&blkif->drain_complete, HZ);
|
|
|
|
if (!atomic_read(&blkif->drain))
|
|
break;
|
|
} while (!kthread_should_stop());
|
|
atomic_set(&blkif->drain, 0);
|
|
}
|
|
|
|
/*
|
|
* Completion callback on the bio's. Called as bh->b_end_io()
|
|
*/
|
|
|
|
static void __end_block_io_op(struct pending_req *pending_req, int error)
|
|
{
|
|
/* An error fails the entire request. */
|
|
if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) &&
|
|
(error == -EOPNOTSUPP)) {
|
|
pr_debug(DRV_PFX "flush diskcache op failed, not supported\n");
|
|
xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
|
|
pending_req->status = BLKIF_RSP_EOPNOTSUPP;
|
|
} else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
|
|
(error == -EOPNOTSUPP)) {
|
|
pr_debug(DRV_PFX "write barrier op failed, not supported\n");
|
|
xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
|
|
pending_req->status = BLKIF_RSP_EOPNOTSUPP;
|
|
} else if (error) {
|
|
pr_debug(DRV_PFX "Buffer not up-to-date at end of operation,"
|
|
" error=%d\n", error);
|
|
pending_req->status = BLKIF_RSP_ERROR;
|
|
}
|
|
|
|
/*
|
|
* If all of the bio's have completed it is time to unmap
|
|
* the grant references associated with 'request' and provide
|
|
* the proper response on the ring.
|
|
*/
|
|
if (atomic_dec_and_test(&pending_req->pendcnt)) {
|
|
xen_blkbk_unmap(pending_req);
|
|
make_response(pending_req->blkif, pending_req->id,
|
|
pending_req->operation, pending_req->status);
|
|
xen_blkif_put(pending_req->blkif);
|
|
if (atomic_read(&pending_req->blkif->refcnt) <= 2) {
|
|
if (atomic_read(&pending_req->blkif->drain))
|
|
complete(&pending_req->blkif->drain_complete);
|
|
}
|
|
free_req(pending_req);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* bio callback.
|
|
*/
|
|
static void end_block_io_op(struct bio *bio, int error)
|
|
{
|
|
__end_block_io_op(bio->bi_private, error);
|
|
bio_put(bio);
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* Function to copy the from the ring buffer the 'struct blkif_request'
|
|
* (which has the sectors we want, number of them, grant references, etc),
|
|
* and transmute it to the block API to hand it over to the proper block disk.
|
|
*/
|
|
static int
|
|
__do_block_io_op(struct xen_blkif *blkif)
|
|
{
|
|
union blkif_back_rings *blk_rings = &blkif->blk_rings;
|
|
struct blkif_request req;
|
|
struct pending_req *pending_req;
|
|
RING_IDX rc, rp;
|
|
int more_to_do = 0;
|
|
|
|
rc = blk_rings->common.req_cons;
|
|
rp = blk_rings->common.sring->req_prod;
|
|
rmb(); /* Ensure we see queued requests up to 'rp'. */
|
|
|
|
while (rc != rp) {
|
|
|
|
if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
|
|
break;
|
|
|
|
if (kthread_should_stop()) {
|
|
more_to_do = 1;
|
|
break;
|
|
}
|
|
|
|
pending_req = alloc_req();
|
|
if (NULL == pending_req) {
|
|
blkif->st_oo_req++;
|
|
more_to_do = 1;
|
|
break;
|
|
}
|
|
|
|
switch (blkif->blk_protocol) {
|
|
case BLKIF_PROTOCOL_NATIVE:
|
|
memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
|
|
break;
|
|
case BLKIF_PROTOCOL_X86_32:
|
|
blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
|
|
break;
|
|
case BLKIF_PROTOCOL_X86_64:
|
|
blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
blk_rings->common.req_cons = ++rc; /* before make_response() */
|
|
|
|
/* Apply all sanity checks to /private copy/ of request. */
|
|
barrier();
|
|
if (unlikely(req.operation == BLKIF_OP_DISCARD)) {
|
|
free_req(pending_req);
|
|
if (dispatch_discard_io(blkif, &req))
|
|
break;
|
|
} else if (dispatch_rw_block_io(blkif, &req, pending_req))
|
|
break;
|
|
|
|
/* Yield point for this unbounded loop. */
|
|
cond_resched();
|
|
}
|
|
|
|
return more_to_do;
|
|
}
|
|
|
|
static int
|
|
do_block_io_op(struct xen_blkif *blkif)
|
|
{
|
|
union blkif_back_rings *blk_rings = &blkif->blk_rings;
|
|
int more_to_do;
|
|
|
|
do {
|
|
more_to_do = __do_block_io_op(blkif);
|
|
if (more_to_do)
|
|
break;
|
|
|
|
RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
|
|
} while (more_to_do);
|
|
|
|
return more_to_do;
|
|
}
|
|
/*
|
|
* Transmutation of the 'struct blkif_request' to a proper 'struct bio'
|
|
* and call the 'submit_bio' to pass it to the underlying storage.
|
|
*/
|
|
static int dispatch_rw_block_io(struct xen_blkif *blkif,
|
|
struct blkif_request *req,
|
|
struct pending_req *pending_req)
|
|
{
|
|
struct phys_req preq;
|
|
struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
|
unsigned int nseg;
|
|
struct bio *bio = NULL;
|
|
struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
|
int i, nbio = 0;
|
|
int operation;
|
|
struct blk_plug plug;
|
|
bool drain = false;
|
|
struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
|
|
|
switch (req->operation) {
|
|
case BLKIF_OP_READ:
|
|
blkif->st_rd_req++;
|
|
operation = READ;
|
|
break;
|
|
case BLKIF_OP_WRITE:
|
|
blkif->st_wr_req++;
|
|
operation = WRITE_ODIRECT;
|
|
break;
|
|
case BLKIF_OP_WRITE_BARRIER:
|
|
drain = true;
|
|
case BLKIF_OP_FLUSH_DISKCACHE:
|
|
blkif->st_f_req++;
|
|
operation = WRITE_FLUSH;
|
|
break;
|
|
default:
|
|
operation = 0; /* make gcc happy */
|
|
goto fail_response;
|
|
break;
|
|
}
|
|
|
|
/* Check that the number of segments is sane. */
|
|
nseg = req->u.rw.nr_segments;
|
|
|
|
if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
|
|
unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
|
|
pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
|
|
nseg);
|
|
/* Haven't submitted any bio's yet. */
|
|
goto fail_response;
|
|
}
|
|
|
|
preq.dev = req->u.rw.handle;
|
|
preq.sector_number = req->u.rw.sector_number;
|
|
preq.nr_sects = 0;
|
|
|
|
pending_req->blkif = blkif;
|
|
pending_req->id = req->u.rw.id;
|
|
pending_req->operation = req->operation;
|
|
pending_req->status = BLKIF_RSP_OKAY;
|
|
pending_req->nr_pages = nseg;
|
|
|
|
for (i = 0; i < nseg; i++) {
|
|
seg[i].nsec = req->u.rw.seg[i].last_sect -
|
|
req->u.rw.seg[i].first_sect + 1;
|
|
if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
|
|
(req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect))
|
|
goto fail_response;
|
|
preq.nr_sects += seg[i].nsec;
|
|
|
|
}
|
|
|
|
if (xen_vbd_translate(&preq, blkif, operation) != 0) {
|
|
pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n",
|
|
operation == READ ? "read" : "write",
|
|
preq.sector_number,
|
|
preq.sector_number + preq.nr_sects, preq.dev);
|
|
goto fail_response;
|
|
}
|
|
|
|
/*
|
|
* This check _MUST_ be done after xen_vbd_translate as the preq.bdev
|
|
* is set there.
|
|
*/
|
|
for (i = 0; i < nseg; i++) {
|
|
if (((int)preq.sector_number|(int)seg[i].nsec) &
|
|
((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
|
|
pr_debug(DRV_PFX "Misaligned I/O request from domain %d",
|
|
blkif->domid);
|
|
goto fail_response;
|
|
}
|
|
}
|
|
|
|
/* Wait on all outstanding I/O's and once that has been completed
|
|
* issue the WRITE_FLUSH.
|
|
*/
|
|
if (drain)
|
|
xen_blk_drain_io(pending_req->blkif);
|
|
|
|
/*
|
|
* If we have failed at this point, we need to undo the M2P override,
|
|
* set gnttab_set_unmap_op on all of the grant references and perform
|
|
* the hypercall to unmap the grants - that is all done in
|
|
* xen_blkbk_unmap.
|
|
*/
|
|
if (xen_blkbk_map(req, pending_req, seg, pages))
|
|
goto fail_flush;
|
|
|
|
/*
|
|
* This corresponding xen_blkif_put is done in __end_block_io_op, or
|
|
* below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
|
|
*/
|
|
xen_blkif_get(blkif);
|
|
|
|
for (i = 0; i < nseg; i++) {
|
|
while ((bio == NULL) ||
|
|
(bio_add_page(bio,
|
|
pages[i],
|
|
seg[i].nsec << 9,
|
|
seg[i].buf & ~PAGE_MASK) == 0)) {
|
|
|
|
bio = bio_alloc(GFP_KERNEL, nseg-i);
|
|
if (unlikely(bio == NULL))
|
|
goto fail_put_bio;
|
|
|
|
biolist[nbio++] = bio;
|
|
bio->bi_bdev = preq.bdev;
|
|
bio->bi_private = pending_req;
|
|
bio->bi_end_io = end_block_io_op;
|
|
bio->bi_sector = preq.sector_number;
|
|
}
|
|
|
|
preq.sector_number += seg[i].nsec;
|
|
}
|
|
|
|
/* This will be hit if the operation was a flush or discard. */
|
|
if (!bio) {
|
|
BUG_ON(operation != WRITE_FLUSH);
|
|
|
|
bio = bio_alloc(GFP_KERNEL, 0);
|
|
if (unlikely(bio == NULL))
|
|
goto fail_put_bio;
|
|
|
|
biolist[nbio++] = bio;
|
|
bio->bi_bdev = preq.bdev;
|
|
bio->bi_private = pending_req;
|
|
bio->bi_end_io = end_block_io_op;
|
|
}
|
|
|
|
/*
|
|
* We set it one so that the last submit_bio does not have to call
|
|
* atomic_inc.
|
|
*/
|
|
atomic_set(&pending_req->pendcnt, nbio);
|
|
|
|
/* Get a reference count for the disk queue and start sending I/O */
|
|
blk_start_plug(&plug);
|
|
|
|
for (i = 0; i < nbio; i++)
|
|
submit_bio(operation, biolist[i]);
|
|
|
|
/* Let the I/Os go.. */
|
|
blk_finish_plug(&plug);
|
|
|
|
if (operation == READ)
|
|
blkif->st_rd_sect += preq.nr_sects;
|
|
else if (operation & WRITE)
|
|
blkif->st_wr_sect += preq.nr_sects;
|
|
|
|
return 0;
|
|
|
|
fail_flush:
|
|
xen_blkbk_unmap(pending_req);
|
|
fail_response:
|
|
/* Haven't submitted any bio's yet. */
|
|
make_response(blkif, req->u.rw.id, req->operation, BLKIF_RSP_ERROR);
|
|
free_req(pending_req);
|
|
msleep(1); /* back off a bit */
|
|
return -EIO;
|
|
|
|
fail_put_bio:
|
|
for (i = 0; i < nbio; i++)
|
|
bio_put(biolist[i]);
|
|
__end_block_io_op(pending_req, -EINVAL);
|
|
msleep(1); /* back off a bit */
|
|
return -EIO;
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* Put a response on the ring on how the operation fared.
|
|
*/
|
|
static void make_response(struct xen_blkif *blkif, u64 id,
|
|
unsigned short op, int st)
|
|
{
|
|
struct blkif_response resp;
|
|
unsigned long flags;
|
|
union blkif_back_rings *blk_rings = &blkif->blk_rings;
|
|
int notify;
|
|
|
|
resp.id = id;
|
|
resp.operation = op;
|
|
resp.status = st;
|
|
|
|
spin_lock_irqsave(&blkif->blk_ring_lock, flags);
|
|
/* Place on the response ring for the relevant domain. */
|
|
switch (blkif->blk_protocol) {
|
|
case BLKIF_PROTOCOL_NATIVE:
|
|
memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
|
|
&resp, sizeof(resp));
|
|
break;
|
|
case BLKIF_PROTOCOL_X86_32:
|
|
memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
|
|
&resp, sizeof(resp));
|
|
break;
|
|
case BLKIF_PROTOCOL_X86_64:
|
|
memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
|
|
&resp, sizeof(resp));
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
blk_rings->common.rsp_prod_pvt++;
|
|
RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
|
|
spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
|
|
if (notify)
|
|
notify_remote_via_irq(blkif->irq);
|
|
}
|
|
|
|
static int __init xen_blkif_init(void)
|
|
{
|
|
int i, mmap_pages;
|
|
int rc = 0;
|
|
|
|
if (!xen_domain())
|
|
return -ENODEV;
|
|
|
|
blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL);
|
|
if (!blkbk) {
|
|
pr_alert(DRV_PFX "%s: out of memory!\n", __func__);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST;
|
|
|
|
blkbk->pending_reqs = kzalloc(sizeof(blkbk->pending_reqs[0]) *
|
|
xen_blkif_reqs, GFP_KERNEL);
|
|
blkbk->pending_grant_handles = kmalloc(sizeof(blkbk->pending_grant_handles[0]) *
|
|
mmap_pages, GFP_KERNEL);
|
|
blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) *
|
|
mmap_pages, GFP_KERNEL);
|
|
|
|
if (!blkbk->pending_reqs || !blkbk->pending_grant_handles ||
|
|
!blkbk->pending_pages) {
|
|
rc = -ENOMEM;
|
|
goto out_of_memory;
|
|
}
|
|
|
|
for (i = 0; i < mmap_pages; i++) {
|
|
blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE;
|
|
blkbk->pending_pages[i] = alloc_page(GFP_KERNEL);
|
|
if (blkbk->pending_pages[i] == NULL) {
|
|
rc = -ENOMEM;
|
|
goto out_of_memory;
|
|
}
|
|
}
|
|
rc = xen_blkif_interface_init();
|
|
if (rc)
|
|
goto failed_init;
|
|
|
|
INIT_LIST_HEAD(&blkbk->pending_free);
|
|
spin_lock_init(&blkbk->pending_free_lock);
|
|
init_waitqueue_head(&blkbk->pending_free_wq);
|
|
|
|
for (i = 0; i < xen_blkif_reqs; i++)
|
|
list_add_tail(&blkbk->pending_reqs[i].free_list,
|
|
&blkbk->pending_free);
|
|
|
|
rc = xen_blkif_xenbus_init();
|
|
if (rc)
|
|
goto failed_init;
|
|
|
|
return 0;
|
|
|
|
out_of_memory:
|
|
pr_alert(DRV_PFX "%s: out of memory\n", __func__);
|
|
failed_init:
|
|
kfree(blkbk->pending_reqs);
|
|
kfree(blkbk->pending_grant_handles);
|
|
if (blkbk->pending_pages) {
|
|
for (i = 0; i < mmap_pages; i++) {
|
|
if (blkbk->pending_pages[i])
|
|
__free_page(blkbk->pending_pages[i]);
|
|
}
|
|
kfree(blkbk->pending_pages);
|
|
}
|
|
kfree(blkbk);
|
|
blkbk = NULL;
|
|
return rc;
|
|
}
|
|
|
|
module_init(xen_blkif_init);
|
|
|
|
MODULE_LICENSE("Dual BSD/GPL");
|
|
MODULE_ALIAS("xen-backend:vbd");
|