[PATCH] 1/5: Device-mapper dm-io.c
From: Alasdair G Kergon
Date: Wed Jun 02 2004 - 10:44:37 EST
dm-io: device-mapper i/o library for kcopyd
--- diff/drivers/md/Makefile 2004-05-09 21:32:38.000000000 -0500
+++ source/drivers/md/Makefile 2004-06-01 19:08:00.000000000 -0500
@@ -3,7 +3,7 @@
#
dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
- dm-ioctl.o
+ dm-ioctl.o dm-io.o
raid6-objs := raid6main.o raid6algos.o raid6recov.o raid6tables.o \
raid6int1.o raid6int2.o raid6int4.o \
raid6int8.o raid6int16.o raid6int32.o \
--- diff/mm/mempool.c 2004-05-09 21:32:52.000000000 -0500
+++ source/mm/mempool.c 2004-06-01 19:08:00.000000000 -0500
@@ -89,11 +89,6 @@
}
EXPORT_SYMBOL(mempool_create);
-/*
- * mempool_resize is disabled for now, because it has no callers. Feel free
- * to turn it back on if needed.
- */
-#if 0
/**
* mempool_resize - resize an existing memory pool
* @pool: pointer to the memory pool which was allocated via
@@ -163,7 +158,6 @@
return 0;
}
EXPORT_SYMBOL(mempool_resize);
-#endif
/**
* mempool_destroy - deallocate a memory pool
--- diff/drivers/md/dm-io.c 1969-12-31 18:00:00.000000000 -0600
+++ source/drivers/md/dm-io.c 2004-06-01 19:11:21.000000000 -0500
@@ -0,0 +1,636 @@
+/*
+ * Copyright (C) 2003 Sistina Software
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-io.h"
+
+#include <linux/bio.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#define BIO_POOL_SIZE 256
+
+
+/*-----------------------------------------------------------------
+ * Bio set, move this to bio.c
+ *---------------------------------------------------------------*/
+#define BV_NAME_SIZE 16
+struct biovec_pool {
+ int nr_vecs;
+ char name[BV_NAME_SIZE];
+ kmem_cache_t *slab;
+ mempool_t *pool;
+ atomic_t allocated; /* FIXME: debug */
+};
+
+#define BIOVEC_NR_POOLS 6
+struct bio_set {
+ char name[BV_NAME_SIZE];
+ kmem_cache_t *bio_slab;
+ mempool_t *bio_pool;
+ struct biovec_pool pools[BIOVEC_NR_POOLS];
+};
+
+static void bio_set_exit(struct bio_set *bs)
+{
+ unsigned i;
+ struct biovec_pool *bp;
+
+ if (bs->bio_pool)
+ mempool_destroy(bs->bio_pool);
+
+ if (bs->bio_slab)
+ kmem_cache_destroy(bs->bio_slab);
+
+ for (i = 0; i < BIOVEC_NR_POOLS; i++) {
+ bp = bs->pools + i;
+ if (bp->pool)
+ mempool_destroy(bp->pool);
+
+ if (bp->slab)
+ kmem_cache_destroy(bp->slab);
+ }
+}
+
+static void mk_name(char *str, size_t len, const char *prefix, unsigned count)
+{
+ snprintf(str, len, "%s-%u", prefix, count);
+}
+
+static int bio_set_init(struct bio_set *bs, const char *slab_prefix,
+ unsigned pool_entries, unsigned scale)
+{
+ /* FIXME: this must match bvec_index(), why not go the
+ * whole hog and have a pool per power of 2 ? */
+ static unsigned _vec_lengths[BIOVEC_NR_POOLS] = {
+ 1, 4, 16, 64, 128, BIO_MAX_PAGES
+ };
+
+
+ unsigned i, size;
+ struct biovec_pool *bp;
+
+ /* zero the bs so we can tear down properly on error */
+ memset(bs, 0, sizeof(*bs));
+
+ /*
+ * Set up the bio pool.
+ */
+ snprintf(bs->name, sizeof(bs->name), "%s-bio", slab_prefix);
+
+ bs->bio_slab = kmem_cache_create(bs->name, sizeof(struct bio), 0,
+ SLAB_HWCACHE_ALIGN, NULL, NULL);
+ if (!bs->bio_slab) {
+ DMWARN("can't init bio slab");
+ goto bad;
+ }
+
+ bs->bio_pool = mempool_create(pool_entries, mempool_alloc_slab,
+ mempool_free_slab, bs->bio_slab);
+ if (!bs->bio_pool) {
+ DMWARN("can't init bio pool");
+ goto bad;
+ }
+
+ /*
+ * Set up the biovec pools.
+ */
+ for (i = 0; i < BIOVEC_NR_POOLS; i++) {
+ bp = bs->pools + i;
+ bp->nr_vecs = _vec_lengths[i];
+ atomic_set(&bp->allocated, 1); /* FIXME: debug */
+
+
+ size = bp->nr_vecs * sizeof(struct bio_vec);
+
+ mk_name(bp->name, sizeof(bp->name), slab_prefix, i);
+ bp->slab = kmem_cache_create(bp->name, size, 0,
+ SLAB_HWCACHE_ALIGN, NULL, NULL);
+ if (!bp->slab) {
+ DMWARN("can't init biovec slab cache");
+ goto bad;
+ }
+
+ if (i >= scale)
+ pool_entries >>= 1;
+
+ bp->pool = mempool_create(pool_entries, mempool_alloc_slab,
+ mempool_free_slab, bp->slab);
+ if (!bp->pool) {
+ DMWARN("can't init biovec mempool");
+ goto bad;
+ }
+ }
+
+ return 0;
+
+ bad:
+ bio_set_exit(bs);
+ return -ENOMEM;
+}
+
+/* FIXME: blech */
+static inline unsigned bvec_index(unsigned nr)
+{
+ switch (nr) {
+ case 1: return 0;
+ case 2 ... 4: return 1;
+ case 5 ... 16: return 2;
+ case 17 ... 64: return 3;
+ case 65 ... 128:return 4;
+ case 129 ... BIO_MAX_PAGES: return 5;
+ }
+
+ BUG();
+ return 0;
+}
+
+static inline void bs_bio_init(struct bio *bio)
+{
+ bio->bi_next = NULL;
+ bio->bi_flags = 1 << BIO_UPTODATE;
+ bio->bi_rw = 0;
+ bio->bi_vcnt = 0;
+ bio->bi_idx = 0;
+ bio->bi_phys_segments = 0;
+ bio->bi_hw_segments = 0;
+ bio->bi_size = 0;
+ bio->bi_max_vecs = 0;
+ bio->bi_end_io = NULL;
+ atomic_set(&bio->bi_cnt, 1);
+ bio->bi_private = NULL;
+}
+
+static unsigned _bio_count = 0;
+struct bio *bio_set_alloc(struct bio_set *bs, int gfp_mask, int nr_iovecs)
+{
+ struct biovec_pool *bp;
+ struct bio_vec *bv = NULL;
+ unsigned long idx;
+ struct bio *bio;
+
+ bio = mempool_alloc(bs->bio_pool, gfp_mask);
+ if (unlikely(!bio))
+ return NULL;
+
+ bio_init(bio);
+
+ if (likely(nr_iovecs)) {
+ idx = bvec_index(nr_iovecs);
+ bp = bs->pools + idx;
+ bv = mempool_alloc(bp->pool, gfp_mask);
+ if (!bv) {
+ mempool_free(bio, bs->bio_pool);
+ return NULL;
+ }
+
+ memset(bv, 0, bp->nr_vecs * sizeof(*bv));
+ bio->bi_flags |= idx << BIO_POOL_OFFSET;
+ bio->bi_max_vecs = bp->nr_vecs;
+ atomic_inc(&bp->allocated);
+ }
+
+ bio->bi_io_vec = bv;
+ return bio;
+}
+
+static void bio_set_free(struct bio_set *bs, struct bio *bio)
+{
+ struct biovec_pool *bp = bs->pools + BIO_POOL_IDX(bio);
+
+ if (atomic_dec_and_test(&bp->allocated))
+ BUG();
+
+ mempool_free(bio->bi_io_vec, bp->pool);
+ mempool_free(bio, bs->bio_pool);
+}
+
+/*-----------------------------------------------------------------
+ * dm-io proper
+ *---------------------------------------------------------------*/
+static struct bio_set _bios;
+
+/* FIXME: can we shrink this ? */
+struct io {
+ unsigned long error;
+ atomic_t count;
+ struct task_struct *sleeper;
+ io_notify_fn callback;
+ void *context;
+};
+
+/*
+ * io contexts are only dynamically allocated for asynchronous
+ * io. Since async io is likely to be the majority of io we'll
+ * have the same number of io contexts as buffer heads ! (FIXME:
+ * must reduce this).
+ */
+static unsigned _num_ios;
+static mempool_t *_io_pool;
+
+static void *alloc_io(int gfp_mask, void *pool_data)
+{
+ return kmalloc(sizeof(struct io), gfp_mask);
+}
+
+static void free_io(void *element, void *pool_data)
+{
+ kfree(element);
+}
+
+static unsigned int pages_to_ios(unsigned int pages)
+{
+ return 4 * pages; /* too many ? */
+}
+
+static int resize_pool(unsigned int new_ios)
+{
+ int r = 0;
+
+ if (_io_pool) {
+ if (new_ios == 0) {
+ /* free off the pool */
+ mempool_destroy(_io_pool);
+ _io_pool = NULL;
+ bio_set_exit(&_bios);
+
+ } else {
+ /* resize the pool */
+ r = mempool_resize(_io_pool, new_ios, GFP_KERNEL);
+ }
+
+ } else {
+ /* create new pool */
+ _io_pool = mempool_create(new_ios, alloc_io, free_io, NULL);
+ if (!_io_pool)
+ r = -ENOMEM;
+
+ r = bio_set_init(&_bios, "dm-io", 512, 1);
+ if (r) {
+ mempool_destroy(_io_pool);
+ _io_pool = NULL;
+ }
+ }
+
+ if (!r)
+ _num_ios = new_ios;
+
+ return r;
+}
+
+int dm_io_get(unsigned int num_pages)
+{
+ return resize_pool(_num_ios + pages_to_ios(num_pages));
+}
+
+void dm_io_put(unsigned int num_pages)
+{
+ resize_pool(_num_ios - pages_to_ios(num_pages));
+}
+
+/*-----------------------------------------------------------------
+ * We need to keep track of which region a bio is doing io for.
+ * In order to save a memory allocation we store this the last
+ * bvec which we know is unused (blech).
+ *---------------------------------------------------------------*/
+static inline void bio_set_region(struct bio *bio, unsigned region)
+{
+ bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len = region;
+}
+
+static inline unsigned bio_get_region(struct bio *bio)
+{
+ return bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len;
+}
+
+/*-----------------------------------------------------------------
+ * We need an io object to keep track of the number of bios that
+ * have been dispatched for a particular io.
+ *---------------------------------------------------------------*/
+static void dec_count(struct io *io, unsigned int region, int error)
+{
+ if (error)
+ set_bit(region, &io->error);
+
+ if (atomic_dec_and_test(&io->count)) {
+ if (io->sleeper)
+ wake_up_process(io->sleeper);
+
+ else {
+ int r = io->error;
+ io_notify_fn fn = io->callback;
+ void *context = io->context;
+
+ mempool_free(io, _io_pool);
+ fn(r, context);
+ }
+ }
+}
+
+/* FIXME Move this to bio.h? */
+static void zero_fill_bio(struct bio *bio)
+{
+ unsigned long flags;
+ struct bio_vec *bv;
+ int i;
+
+ bio_for_each_segment(bv, bio, i) {
+ char *data = bvec_kmap_irq(bv, &flags);
+ memset(data, 0, bv->bv_len);
+ bvec_kunmap_irq(bv, &flags);
+ }
+}
+
+static int endio(struct bio *bio, unsigned int done, int error)
+{
+ struct io *io = (struct io *) bio->bi_private;
+
+ /* keep going until we've finished */
+ if (bio->bi_size)
+ return 1;
+
+ if (error && bio_data_dir(bio) == READ)
+ zero_fill_bio(bio);
+
+ dec_count(io, bio_get_region(bio), error);
+ bio_put(bio);
+
+ return 0;
+}
+
+static void bio_dtr(struct bio *bio)
+{
+ _bio_count--;
+ bio_set_free(&_bios, bio);
+}
+
+/*-----------------------------------------------------------------
+ * These little objects provide an abstraction for getting a new
+ * destination page for io.
+ *---------------------------------------------------------------*/
+struct dpages {
+ void (*get_page)(struct dpages *dp,
+ struct page **p, unsigned long *len, unsigned *offset);
+ void (*next_page)(struct dpages *dp);
+
+ unsigned context_u;
+ void *context_ptr;
+};
+
+/*
+ * Functions for getting the pages from a list.
+ */
+static void list_get_page(struct dpages *dp,
+ struct page **p, unsigned long *len, unsigned *offset)
+{
+ unsigned o = dp->context_u;
+ struct page_list *pl = (struct page_list *) dp->context_ptr;
+
+ *p = pl->page;
+ *len = PAGE_SIZE - o;
+ *offset = o;
+}
+
+static void list_next_page(struct dpages *dp)
+{
+ struct page_list *pl = (struct page_list *) dp->context_ptr;
+ dp->context_ptr = pl->next;
+ dp->context_u = 0;
+}
+
+static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
+{
+ dp->get_page = list_get_page;
+ dp->next_page = list_next_page;
+ dp->context_u = offset;
+ dp->context_ptr = pl;
+}
+
+/*
+ * Functions for getting the pages from a bvec.
+ */
+static void bvec_get_page(struct dpages *dp,
+ struct page **p, unsigned long *len, unsigned *offset)
+{
+ struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
+ *p = bvec->bv_page;
+ *len = bvec->bv_len;
+ *offset = bvec->bv_offset;
+}
+
+static void bvec_next_page(struct dpages *dp)
+{
+ struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
+ dp->context_ptr = bvec + 1;
+}
+
+static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec)
+{
+ dp->get_page = bvec_get_page;
+ dp->next_page = bvec_next_page;
+ dp->context_ptr = bvec;
+}
+
+static void vm_get_page(struct dpages *dp,
+ struct page **p, unsigned long *len, unsigned *offset)
+{
+ *p = vmalloc_to_page(dp->context_ptr);
+ *offset = dp->context_u;
+ *len = PAGE_SIZE - dp->context_u;
+}
+
+static void vm_next_page(struct dpages *dp)
+{
+ dp->context_ptr += PAGE_SIZE - dp->context_u;
+ dp->context_u = 0;
+}
+
+static void vm_dp_init(struct dpages *dp, void *data)
+{
+ dp->get_page = vm_get_page;
+ dp->next_page = vm_next_page;
+ dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
+ dp->context_ptr = data;
+}
+
+/*-----------------------------------------------------------------
+ * IO routines that accept a list of pages.
+ *---------------------------------------------------------------*/
+static void do_region(int rw, unsigned int region, struct io_region *where,
+ struct dpages *dp, struct io *io)
+{
+ struct bio *bio;
+ struct page *page;
+ unsigned long len;
+ unsigned offset;
+ unsigned num_bvecs;
+ sector_t remaining = where->count;
+
+ while (remaining) {
+ /*
+ * Allocate a suitably sized bio, we add an extra
+ * bvec for bio_get/set_region().
+ */
+ num_bvecs = (remaining / (PAGE_SIZE >> 9)) + 2;
+ _bio_count++;
+ bio = bio_set_alloc(&_bios, GFP_NOIO, num_bvecs);
+ bio->bi_sector = where->sector + (where->count - remaining);
+ bio->bi_bdev = where->bdev;
+ bio->bi_end_io = endio;
+ bio->bi_private = io;
+ bio->bi_destructor = bio_dtr;
+ bio_set_region(bio, region);
+
+ /*
+ * Try and add as many pages as possible.
+ */
+ while (remaining) {
+ dp->get_page(dp, &page, &len, &offset);
+ len = min(len, to_bytes(remaining));
+ if (!bio_add_page(bio, page, len, offset))
+ break;
+
+ offset = 0;
+ remaining -= to_sector(len);
+ dp->next_page(dp);
+ }
+
+ atomic_inc(&io->count);
+ submit_bio(rw, bio);
+ }
+}
+
+static void dispatch_io(int rw, unsigned int num_regions,
+ struct io_region *where, struct dpages *dp,
+ struct io *io, int sync)
+{
+ int i;
+ struct dpages old_pages = *dp;
+
+ if (sync)
+ rw |= (1 << BIO_RW_SYNC);
+
+ /*
+ * For multiple regions we need to be careful to rewind
+ * the dp object for each call to do_region.
+ */
+ for (i = 0; i < num_regions; i++) {
+ *dp = old_pages;
+ if (where[i].count)
+ do_region(rw, i, where + i, dp, io);
+ }
+
+ /*
+ * Drop the extra refence that we were holding to avoid
+ * the io being completed too early.
+ */
+ dec_count(io, 0, 0);
+}
+
+static int sync_io(unsigned int num_regions, struct io_region *where,
+ int rw, struct dpages *dp, unsigned long *error_bits)
+{
+ struct io io;
+
+ BUG_ON(num_regions > 1 && rw != WRITE);
+
+ io.error = 0;
+ atomic_set(&io.count, 1); /* see dispatch_io() */
+ io.sleeper = current;
+
+ dispatch_io(rw, num_regions, where, dp, &io, 1);
+
+ while (1) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+
+ if (!atomic_read(&io.count) || signal_pending(current))
+ break;
+
+ io_schedule();
+ }
+ set_current_state(TASK_RUNNING);
+
+ if (atomic_read(&io.count))
+ return -EINTR;
+
+ *error_bits = io.error;
+ return io.error ? -EIO : 0;
+}
+
+static int async_io(unsigned int num_regions, struct io_region *where, int rw,
+ struct dpages *dp, io_notify_fn fn, void *context)
+{
+ struct io *io = mempool_alloc(_io_pool, GFP_NOIO);
+
+ io->error = 0;
+ atomic_set(&io->count, 1); /* see dispatch_io() */
+ io->sleeper = NULL;
+ io->callback = fn;
+ io->context = context;
+
+ dispatch_io(rw, num_regions, where, dp, io, 0);
+ return 0;
+}
+
+int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
+ struct page_list *pl, unsigned int offset,
+ unsigned long *error_bits)
+{
+ struct dpages dp;
+ list_dp_init(&dp, pl, offset);
+ return sync_io(num_regions, where, rw, &dp, error_bits);
+}
+
+int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
+ struct bio_vec *bvec, unsigned long *error_bits)
+{
+ struct dpages dp;
+ bvec_dp_init(&dp, bvec);
+ return sync_io(num_regions, where, rw, &dp, error_bits);
+}
+
+int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
+ void *data, unsigned long *error_bits)
+{
+ struct dpages dp;
+ vm_dp_init(&dp, data);
+ return sync_io(num_regions, where, rw, &dp, error_bits);
+}
+
+int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
+ struct page_list *pl, unsigned int offset,
+ io_notify_fn fn, void *context)
+{
+ struct dpages dp;
+ list_dp_init(&dp, pl, offset);
+ return async_io(num_regions, where, rw, &dp, fn, context);
+}
+
+int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
+ struct bio_vec *bvec, io_notify_fn fn, void *context)
+{
+ struct dpages dp;
+ bvec_dp_init(&dp, bvec);
+ return async_io(num_regions, where, rw, &dp, fn, context);
+}
+
+int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
+ void *data, io_notify_fn fn, void *context)
+{
+ struct dpages dp;
+ vm_dp_init(&dp, data);
+ return async_io(num_regions, where, rw, &dp, fn, context);
+}
+
+EXPORT_SYMBOL(dm_io_get);
+EXPORT_SYMBOL(dm_io_put);
+EXPORT_SYMBOL(dm_io_sync);
+EXPORT_SYMBOL(dm_io_async);
+EXPORT_SYMBOL(dm_io_sync_bvec);
+EXPORT_SYMBOL(dm_io_async_bvec);
+EXPORT_SYMBOL(dm_io_sync_vm);
+EXPORT_SYMBOL(dm_io_async_vm);
--- diff/drivers/md/dm-io.h 1969-12-31 18:00:00.000000000 -0600
+++ source/drivers/md/dm-io.h 2004-06-01 19:08:00.000000000 -0500
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2003 Sistina Software
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _DM_IO_H
+#define _DM_IO_H
+
+#include "dm.h"
+
+/* FIXME make this configurable */
+#define DM_MAX_IO_REGIONS 8
+
+struct io_region {
+ struct block_device *bdev;
+ sector_t sector;
+ sector_t count;
+};
+
+struct page_list {
+ struct page_list *next;
+ struct page *page;
+};
+
+
+/*
+ * 'error' is a bitset, with each bit indicating whether an error
+ * occurred doing io to the corresponding region.
+ */
+typedef void (*io_notify_fn)(unsigned long error, void *context);
+
+
+/*
+ * Before anyone uses the IO interface they should call
+ * dm_io_get(), specifying roughly how many pages they are
+ * expecting to perform io on concurrently.
+ *
+ * This function may block.
+ */
+int dm_io_get(unsigned int num_pages);
+void dm_io_put(unsigned int num_pages);
+
+/*
+ * Synchronous IO.
+ *
+ * Please ensure that the rw flag in the next two functions is
+ * either READ or WRITE, ie. we don't take READA. Any
+ * regions with a zero count field will be ignored.
+ */
+int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
+ struct page_list *pl, unsigned int offset,
+ unsigned long *error_bits);
+
+int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
+ struct bio_vec *bvec, unsigned long *error_bits);
+
+int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
+ void *data, unsigned long *error_bits);
+
+/*
+ * Aynchronous IO.
+ *
+ * The 'where' array may be safely allocated on the stack since
+ * the function takes a copy.
+ */
+int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
+ struct page_list *pl, unsigned int offset,
+ io_notify_fn fn, void *context);
+
+int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
+ struct bio_vec *bvec, io_notify_fn fn, void *context);
+
+int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
+ void *data, io_notify_fn fn, void *context);
+
+#endif
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