On Sat, Sep 08, 2012 at 12:35:22PM -0400, Mikulas Patocka wrote: > Another thing - please resend your code with "Signed-off-by". Read the > meaning of "Signed-off-by" in Documentation/SubmittingPatches, agree to > the terms and append "Signed-off-by: Jim Ramsay <jim_ramsay@xxxxxxxx>" to > the code. It is a legal requirement, so that you certify that the code is > under the open source license and that you have the right to distribute > the code. I am attaching below an updated version of your 'dm-switch.c' file, based on your latest post in http://www.redhat.com/archives/dm-devel/2012-August/msg00224.html that makes the following changes: 1. Support for FLUSH and DISCARD operations by implementing target_type.iterate_devices and handling (bio->bi_rw & REQ_FLUSH) in switch_map. Sends DISCARD to one path, FLUSH to each path. 2. Send IOCTLs to the device who owns sector 0, instead of pctx->dev_list[0] 3. Copyright notice update in header, plus adding myself to MODULE_AUTHOR Signed-off-by: Jim Ramsay <jim_ramsay@xxxxxxxx> ------ dm-switch.c ------ /* * Copyright (c) 2010-2012 by Dell Inc. All rights reserved. * * This file is released under the GPL. * * Description: * * file: dm-switch.c * authors: Kevin_OKelley@xxxxxxxx * Jim_Ramsay@xxxxxxxx * Narendran_Ganapathy@xxxxxxxx * mpatocka@xxxxxxxxxx * * This file implements a "switch" target which efficiently implements a * mapping of IOs to underlying block devices in scenarios where there are: * (1) a large number of address regions * (2) a fixed size equal across all address regions * (3) no pattern than allows for a compact description with something like * the dm-stripe target. */ #include <linux/module.h> #include <linux/init.h> #include <linux/device-mapper.h> #include <linux/vmalloc.h> #define DM_MSG_PREFIX "switch" /* * Switch device context block: A new one is created for each dm device. * Contains an array of devices from which we have taken references. */ struct switch_dev { struct dm_dev *dmdev; sector_t start; }; typedef unsigned long pt_entry; /* Switch context header */ struct switch_ctx { unsigned dev_count; /* Number of devices */ unsigned page_size; /* Page size in 512B sectors */ unsigned long n_pages; /* Number of pages */ signed char page_size_bits; /* log2 of page_size or -1 */ unsigned char pte_size; /* Page table entry size in bits */ unsigned char pte_fields; /* Number of entries per pt_entry */ signed char pte_fields_bits; /* log2 of pte_fields or -1 */ pt_entry *page_table; /* Page table */ /* Array of dm devices to switch between */ struct switch_dev dev_list[0]; }; static inline void switch_get_position(struct switch_ctx *pctx, unsigned long page, unsigned long *index, unsigned *bit) { if (pctx->pte_fields_bits >= 0) { *index = page >> pctx->pte_fields_bits; *bit = page & (pctx->pte_fields - 1); } else { *index = page / pctx->pte_fields; *bit = page % pctx->pte_fields; } *bit *= pctx->pte_size; } static inline unsigned switch_get_deviceidx(struct switch_ctx *pctx, sector_t sector) { unsigned long index; unsigned bit, idev; sector_t p; p = sector; if (pctx->page_size_bits >= 0) p >>= pctx->page_size_bits; else sector_div(p, pctx->page_size); switch_get_position(pctx, p, &index, &bit); idev = (ACCESS_ONCE(pctx->page_table[index]) >> bit) & ((1 << pctx->pte_size) - 1); /* This can only happen if the processor uses non-atomic stores. */ if (unlikely(idev >= pctx->dev_count)) idev = 0; return idev; } static void switch_page_table_write(struct switch_ctx *pctx, unsigned long page, unsigned value) { unsigned long index; unsigned bit; pt_entry pte; switch_get_position(pctx, page, &index, &bit); pte = pctx->page_table[index]; pte &= ~((((pt_entry)1 << pctx->pte_size) - 1) << bit); pte |= (pt_entry)value << bit; pctx->page_table[index] = pte; } /* * Constructor: Called each time a dmsetup command creates a dm device. The * target parameter will already have the table, type, begin and len fields * filled in. Arguments are in pairs: <dev_path> <offset>. Therefore, we get * multiple constructor calls, but we will need to build a list of switch_ctx * blocks so that the page table information gets matched to the correct * device. */ static int switch_ctr(struct dm_target *ti, unsigned argc, char **argv) { unsigned a; int n; int r; unsigned dev_count; struct switch_ctx *pctx; sector_t dev_size; unsigned long e; if (argc < 4) { ti->error = "Insufficient arguments"; r = -EINVAL; goto error; } if (kstrtouint(argv[0], 10, &dev_count) || !dev_count || dev_count > (KMALLOC_MAX_SIZE - sizeof(struct switch_ctx)) / sizeof(struct switch_dev)) { ti->error = "Invalid device count"; r = -EINVAL; goto error; } if (dev_count != (argc - 2) / 2) { ti->error = "Invalid argument count"; r = -EINVAL; goto error; } pctx = kmalloc(sizeof(struct switch_ctx) + (dev_count * sizeof(struct switch_dev)), GFP_KERNEL); if (!pctx) { ti->error = "Cannot allocate redirect context"; r = -ENOMEM; goto error; } pctx->dev_count = dev_count; if (kstrtouint(argv[1], 10, &pctx->page_size) || !pctx->page_size) { ti->error = "Invalid page size"; r = -EINVAL; goto error_kfree; } if (!(pctx->page_size & (pctx->page_size - 1))) pctx->page_size_bits = __ffs(pctx->page_size); else pctx->page_size_bits = -1; pctx->pte_size = 1; while (pctx->pte_size < sizeof(pt_entry) * 8 && (pt_entry)1 << pctx->pte_size < pctx->dev_count) pctx->pte_size++; pctx->pte_fields = (sizeof(pt_entry) * 8) / pctx->pte_size; if (!(pctx->pte_fields & (pctx->pte_fields - 1))) pctx->pte_fields_bits = __ffs(pctx->pte_fields); else pctx->pte_fields_bits = -1; dev_size = ti->len; if (sector_div(dev_size, pctx->page_size)) dev_size++; pctx->n_pages = dev_size; if (pctx->n_pages != dev_size || pctx->n_pages >= ULONG_MAX) { ti->error = "Too long page table"; r = -EINVAL; goto error_kfree; } if (sector_div(dev_size, pctx->pte_fields)) dev_size++; if (dev_size > ULONG_MAX / sizeof(pt_entry)) { ti->error = "Too long page table"; r = -EINVAL; goto error_kfree; } r = dm_set_target_max_io_len(ti, pctx->page_size); if (r) goto error_kfree; pctx->page_table = vmalloc(dev_size * sizeof(pt_entry)); if (!pctx->page_table) { ti->error = "Cannot allocate page table"; r = -ENOMEM; goto error_kfree; } a = 0; for (e = 0; e < pctx->n_pages; e++) { switch_page_table_write(pctx, e, a); a++; if (a >= pctx->dev_count) a = 0; } /* * Check each device beneath the target to ensure that the limits are * consistent. */ for (n = 0, a = 2; n < pctx->dev_count; n++, a += 2) { struct dm_dev *dm; sector_t dev_size; unsigned long long start; if (kstrtoull(argv[a + 1], 10, &start) || start != (sector_t)start) { ti->error = "Invalid device starting offset"; r = -EINVAL; n--; goto error_release_n; } r = dm_get_device (ti, argv[a], dm_table_get_mode(ti->table), &dm); if (r) { ti->error = "Device lookup failed"; n--; goto error_release_n; } pctx->dev_list[n].dmdev = dm; pctx->dev_list[n].start = start; dev_size = i_size_read(dm->bdev->bd_inode) >> SECTOR_SHIFT; if (ti->len > start + dev_size) { ti->error = "Device is too small"; r = -EINVAL; goto error_release_n; } } /* For UNMAP, sending the request down any path is sufficient */ ti->num_discard_requests = 1; /* For FLUSH, we should flush each path */ ti->num_flush_requests = pctx->dev_count; ti->private = pctx; return 0; error_release_n: /* De-reference all devices */ for (; n >= 0; n--) dm_put_device(ti, pctx->dev_list[n].dmdev); vfree(pctx->page_table); error_kfree: kfree(pctx); error: return r; } /* * Destructor: Don't free the dm_target, just the ti->private data (if any). */ static void switch_dtr(struct dm_target *ti) { int n; struct switch_ctx *pctx = ti->private; for (n = 0; n < pctx->dev_count; n++) dm_put_device(ti, pctx->dev_list[n].dmdev); vfree(pctx->page_table); kfree(pctx); } static int switch_map(struct dm_target *ti, struct bio *bio, union map_info *map_context) { struct switch_ctx *pctx = ti->private; sector_t offset = bio->bi_sector - ti->begin; unsigned idev; if (bio->bi_rw & REQ_FLUSH) { int request_nr = map_context->target_request_nr; BUG_ON(request_nr >= pctx->dev_count); bio->bi_bdev = pctx->dev_list[request_nr].dmdev->bdev; return DM_MAPIO_REMAPPED; } idev = switch_get_deviceidx(pctx, offset); bio->bi_bdev = pctx->dev_list[idev].dmdev->bdev; bio->bi_sector = pctx->dev_list[idev].start + offset; return DM_MAPIO_REMAPPED; } /* * We need to parse hex numbers as fast as possible. * Message is used to load the whole table. * * This table-based hex parser improves performance. * It improves a time to load 1000000 entries compared to the condition-based * parser. * table-based parser condition-based parser * PA-RISC 0.29s 0.31s * Opteron 0.0495s 0.0498s */ static const unsigned char hex_table[256] = { 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 0,1,2,3,4,5,6,7,8,9,255,255,255,255,255,255, 255,10,11,12,13,14,15,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,10,11,12,13,14,15,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255 }; static inline void parse_hex(const char *string, sector_t *result, const char **end) { unsigned char d; sector_t r = 0; #if 1 while ((d = hex_table[(unsigned char)*string]) < 16) { r = (r << 4) | d; string++; } #else while (1) { d = *string; if (d >= '0' && d <= '9') d -= '0'; else if (d >= 'A' && d <= 'F') d -= 'A' - 10; else if (d >= 'a' && d <= 'f') d -= 'a' - 10; else break; r = (r << 4) | d; string++; } #endif *end = string; *result = r; } static int switch_message(struct dm_target *ti, unsigned argc, char **argv) { static DEFINE_MUTEX(message_mutex); struct switch_ctx *pctx = ti->private; int r; mutex_lock(&message_mutex); if (!argc) { goto invalid_message; } else if (!strcasecmp(argv[0], "set-table")) { unsigned i; sector_t table_index = 0; for (i = 1; i < argc; i++) { sector_t device; const char *string = argv[i]; if (*string == ':') table_index++; else { parse_hex(string, &table_index, &string); if (unlikely(*string != ':')) { invalid_table: DMWARN("invalid set-table argument"); r = -EINVAL; goto ret; } } string++; if (unlikely(!*string)) goto invalid_table; parse_hex(string, &device, &string); if (unlikely(*string)) goto invalid_table; if (unlikely(table_index >= pctx->n_pages)) { DMWARN("invalid set-table page"); r = -EINVAL; goto ret; } if (unlikely(device >= pctx->dev_count)) { DMWARN("invalid set-table device"); r = -EINVAL; goto ret; } switch_page_table_write(pctx, table_index, device); } r = 0; } else { invalid_message: DMWARN("unrecognised message received."); r = -EINVAL; } ret: mutex_unlock(&message_mutex); return r; } static int switch_status(struct dm_target *ti, status_type_t type, unsigned status_flags, char *result, unsigned maxlen) { struct switch_ctx *pctx = ti->private; unsigned sz = 0; int n; result[0] = '\0'; switch (type) { case STATUSTYPE_INFO: result[0] = 0; break; case STATUSTYPE_TABLE: DMEMIT("%u %u", pctx->dev_count, pctx->page_size); for (n = 0; n < pctx->dev_count; n++) { DMEMIT(" %s %llu", pctx->dev_list[n].dmdev->name, (unsigned long long)pctx->dev_list[n].start); } break; default: return 0; } return 0; } /* * Switch ioctl: * * Passthrough all ioctls to the path for sector 0 */ static int switch_ioctl(struct dm_target *ti, unsigned cmd, unsigned long arg) { struct switch_ctx *pctx = ti->private; struct block_device *bdev; fmode_t mode; unsigned idev; idev = switch_get_deviceidx(pctx, 0); bdev = pctx->dev_list[idev].dmdev->bdev; mode = pctx->dev_list[idev].dmdev->mode; return __blkdev_driver_ioctl(bdev, mode, cmd, arg); } static int switch_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data) { struct switch_ctx *pctx = (struct switch_ctx *)ti->private; int n, ret = 0; for (n = 0; n < pctx->dev_count; n++) { ret = fn(ti, pctx->dev_list[n].dmdev, ti->begin, ti->len, data); if (ret) goto out; } out: return ret; } static struct target_type switch_target = { .name = "switch", .version = {1, 0, 0}, .module = THIS_MODULE, .ctr = switch_ctr, .dtr = switch_dtr, .map = switch_map, .message = switch_message, .status = switch_status, .ioctl = switch_ioctl, .iterate_devices = switch_iterate_devices, }; int __init dm_switch_init(void) { int r; r = dm_register_target(&switch_target); if (r) { DMERR("dm_register_target() failed %d", r); return r; } return 0; } void dm_switch_exit(void) { dm_unregister_target(&switch_target); } module_init(dm_switch_init); module_exit(dm_switch_exit); MODULE_DESCRIPTION(DM_NAME " fixed-size address-region-mapping throughput-oriented path selector"); MODULE_AUTHOR("Kevin D. O'Kelley <Kevin_OKelley@xxxxxxxx>"); MODULE_AUTHOR("Jim Ramsay <Jim_Ramsay@xxxxxxxx>"); MODULE_AUTHOR("Mikulas Patocka <mpatocka@xxxxxxxxxx>"); MODULE_LICENSE("GPL"); ------------------------- -- Jim Ramsay -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel -- Jim Ramsay -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
