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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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#include "dm.h"#include <linux/module.h>#include <linux/workqueue.h>#include <linux/dm-bufio.h>
#define DM_MSG_PREFIX "ebs"
static void ebs_dtr(struct dm_target *ti);
/* Emulated block size context. */struct ebs_c { struct dm_dev *dev; /* Underlying device to emulate block size on. */ struct dm_bufio_client *bufio; /* Use dm-bufio for read and read-modify-write processing. */ struct workqueue_struct *wq; /* Workqueue for ^ processing of bios. */ struct work_struct ws; /* Work item used for ^. */ struct bio_list bios_in; /* Worker bios input list. */ spinlock_t lock; /* Guard bios input list above. */ sector_t start; /* <start> table line argument, see ebs_ctr below. */ unsigned int e_bs; /* Emulated block size in sectors exposed to upper layer. */ unsigned int u_bs; /* Underlying block size in sectors retrieved from/set on lower layer device. */ unsigned char block_shift; /* bitshift sectors -> blocks used in dm-bufio API. */ bool u_bs_set:1; /* Flag to indicate underlying block size is set on table line. */};
static inline sector_t __sector_to_block(struct ebs_c *ec, sector_t sector){ return sector >> ec->block_shift;}
static inline sector_t __block_mod(sector_t sector, unsigned int bs){ return sector & (bs - 1);}
/* Return number of blocks for a bio, accounting for misalignment of start and end sectors. */static inline unsigned int __nr_blocks(struct ebs_c *ec, struct bio *bio){ sector_t end_sector = __block_mod(bio->bi_iter.bi_sector, ec->u_bs) + bio_sectors(bio);
return __sector_to_block(ec, end_sector) + (__block_mod(end_sector, ec->u_bs) ? 1 : 0);}
static inline bool __ebs_check_bs(unsigned int bs){ return bs && is_power_of_2(bs);}
/* * READ/WRITE: * * copy blocks between bufio blocks and bio vector's (partial/overlapping) pages. */static int __ebs_rw_bvec(struct ebs_c *ec, enum req_op op, struct bio_vec *bv, struct bvec_iter *iter){ int r = 0; unsigned char *ba, *pa; unsigned int cur_len; unsigned int bv_len = bv->bv_len; unsigned int buf_off = to_bytes(__block_mod(iter->bi_sector, ec->u_bs)); sector_t block = __sector_to_block(ec, iter->bi_sector); struct dm_buffer *b;
if (unlikely(!bv->bv_page || !bv_len)) return -EIO;
pa = bvec_virt(bv);
/* Handle overlapping page <-> blocks */ while (bv_len) { cur_len = min(dm_bufio_get_block_size(ec->bufio) - buf_off, bv_len);
/* Avoid reading for writes in case bio vector's page overwrites block completely. */ if (op == REQ_OP_READ || buf_off || bv_len < dm_bufio_get_block_size(ec->bufio)) ba = dm_bufio_read(ec->bufio, block, &b); else ba = dm_bufio_new(ec->bufio, block, &b);
if (IS_ERR(ba)) { /* * Carry on with next buffer, if any, to issue all possible * data but return error. */ r = PTR_ERR(ba); } else { /* Copy data to/from bio to buffer if read/new was successful above. */ ba += buf_off; if (op == REQ_OP_READ) { memcpy(pa, ba, cur_len); flush_dcache_page(bv->bv_page); } else { flush_dcache_page(bv->bv_page); memcpy(ba, pa, cur_len); dm_bufio_mark_buffer_dirty(b); }
dm_bufio_release(b); }
pa += cur_len; bv_len -= cur_len; buf_off = 0; block++; }
return r;}
/* READ/WRITE: iterate bio vector's copying between (partial) pages and bufio blocks. */static int __ebs_rw_bio(struct ebs_c *ec, enum req_op op, struct bio *bio){ int r = 0, rr; struct bio_vec bv; struct bvec_iter iter;
bio_for_each_bvec(bv, bio, iter) { rr = __ebs_rw_bvec(ec, op, &bv, &iter); if (rr) r = rr; }
return r;}
/* * Discard bio's blocks, i.e. pass discards down. * * Avoid discarding partial blocks at beginning and end; * return 0 in case no blocks can be discarded as a result. */static int __ebs_discard_bio(struct ebs_c *ec, struct bio *bio){ sector_t block, blocks, sector = bio->bi_iter.bi_sector;
block = __sector_to_block(ec, sector); blocks = __nr_blocks(ec, bio);
/* * Partial first underlying block (__nr_blocks() may have * resulted in one block). */ if (__block_mod(sector, ec->u_bs)) { block++; blocks--; }
/* Partial last underlying block if any. */ if (blocks && __block_mod(bio_end_sector(bio), ec->u_bs)) blocks--;
return blocks ? dm_bufio_issue_discard(ec->bufio, block, blocks) : 0;}
/* Release blocks them from the bufio cache. */static void __ebs_forget_bio(struct ebs_c *ec, struct bio *bio){ sector_t blocks, sector = bio->bi_iter.bi_sector;
blocks = __nr_blocks(ec, bio);
dm_bufio_forget_buffers(ec->bufio, __sector_to_block(ec, sector), blocks);}
/* Worker function to process incoming bios. */static void __ebs_process_bios(struct work_struct *ws){ int r; bool write = false; sector_t block1, block2; struct ebs_c *ec = container_of(ws, struct ebs_c, ws); struct bio *bio; struct bio_list bios;
bio_list_init(&bios);
spin_lock_irq(&ec->lock); bios = ec->bios_in; bio_list_init(&ec->bios_in); spin_unlock_irq(&ec->lock);
/* Prefetch all read and any mis-aligned write buffers */ bio_list_for_each(bio, &bios) { block1 = __sector_to_block(ec, bio->bi_iter.bi_sector); if (bio_op(bio) == REQ_OP_READ) dm_bufio_prefetch(ec->bufio, block1, __nr_blocks(ec, bio)); else if (bio_op(bio) == REQ_OP_WRITE && !(bio->bi_opf & REQ_PREFLUSH)) { block2 = __sector_to_block(ec, bio_end_sector(bio)); if (__block_mod(bio->bi_iter.bi_sector, ec->u_bs)) dm_bufio_prefetch(ec->bufio, block1, 1); if (__block_mod(bio_end_sector(bio), ec->u_bs) && block2 != block1) dm_bufio_prefetch(ec->bufio, block2, 1); } }
bio_list_for_each(bio, &bios) { r = -EIO; if (bio_op(bio) == REQ_OP_READ) r = __ebs_rw_bio(ec, REQ_OP_READ, bio); else if (bio_op(bio) == REQ_OP_WRITE) { write = true; r = __ebs_rw_bio(ec, REQ_OP_WRITE, bio); } else if (bio_op(bio) == REQ_OP_DISCARD) { __ebs_forget_bio(ec, bio); r = __ebs_discard_bio(ec, bio); }
if (r < 0) bio->bi_status = errno_to_blk_status(r); }
/* * We write dirty buffers after processing I/O on them * but before we endio thus addressing REQ_FUA/REQ_SYNC. */ r = write ? dm_bufio_write_dirty_buffers(ec->bufio) : 0;
while ((bio = bio_list_pop(&bios))) { /* Any other request is endioed. */ if (unlikely(r && bio_op(bio) == REQ_OP_WRITE)) bio_io_error(bio); else bio_endio(bio); }}
/* * Construct an emulated block size mapping: <dev_path> <offset> <ebs> [<ubs>] * * <dev_path>: path of the underlying device * <offset>: offset in 512 bytes sectors into <dev_path> * <ebs>: emulated block size in units of 512 bytes exposed to the upper layer * [<ubs>]: underlying block size in units of 512 bytes imposed on the lower layer; * optional, if not supplied, retrieve logical block size from underlying device */static int ebs_ctr(struct dm_target *ti, unsigned int argc, char **argv){ int r; unsigned short tmp1; unsigned long long tmp; char dummy; struct ebs_c *ec;
if (argc < 3 || argc > 4) { ti->error = "Invalid argument count"; return -EINVAL; }
ec = ti->private = kzalloc_obj(*ec); if (!ec) { ti->error = "Cannot allocate ebs context"; return -ENOMEM; }
r = -EINVAL; if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) { ti->error = "Invalid device offset sector"; goto bad; } ec->start = tmp;
if (sscanf(argv[2], "%hu%c", &tmp1, &dummy) != 1 || !__ebs_check_bs(tmp1) || to_bytes(tmp1) > PAGE_SIZE) { ti->error = "Invalid emulated block size"; goto bad; } ec->e_bs = tmp1;
if (argc > 3) { if (sscanf(argv[3], "%hu%c", &tmp1, &dummy) != 1 || !__ebs_check_bs(tmp1)) { ti->error = "Invalid underlying block size"; goto bad; } ec->u_bs = tmp1; ec->u_bs_set = true; } else ec->u_bs_set = false;
r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &ec->dev); if (r) { ti->error = "Device lookup failed"; ec->dev = NULL; goto bad; }
r = -EINVAL; if (!ec->u_bs_set) { ec->u_bs = to_sector(bdev_logical_block_size(ec->dev->bdev)); if (!__ebs_check_bs(ec->u_bs)) { ti->error = "Invalid retrieved underlying block size"; goto bad; } }
if (!ec->u_bs_set && ec->e_bs == ec->u_bs) DMINFO("Emulation superfluous: emulated equal to underlying block size");
if (__block_mod(ec->start, ec->u_bs)) { ti->error = "Device offset must be multiple of underlying block size"; goto bad; }
ec->bufio = dm_bufio_client_create(ec->dev->bdev, to_bytes(ec->u_bs), 1, 0, NULL, NULL, 0); if (IS_ERR(ec->bufio)) { ti->error = "Cannot create dm bufio client"; r = PTR_ERR(ec->bufio); ec->bufio = NULL; goto bad; }
ec->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM); if (!ec->wq) { ti->error = "Cannot create dm-" DM_MSG_PREFIX " workqueue"; r = -ENOMEM; goto bad; }
ec->block_shift = __ffs(ec->u_bs); INIT_WORK(&ec->ws, &__ebs_process_bios); bio_list_init(&ec->bios_in); spin_lock_init(&ec->lock);
ti->num_flush_bios = 1; ti->num_discard_bios = 1; ti->num_secure_erase_bios = 0; ti->num_write_zeroes_bios = 0; return 0;bad: ebs_dtr(ti); return r;}
static void ebs_dtr(struct dm_target *ti){ struct ebs_c *ec = ti->private;
if (ec->wq) destroy_workqueue(ec->wq); if (ec->bufio) dm_bufio_client_destroy(ec->bufio); if (ec->dev) dm_put_device(ti, ec->dev); kfree(ec);}
static int ebs_map(struct dm_target *ti, struct bio *bio){ struct ebs_c *ec = ti->private;
bio_set_dev(bio, ec->dev->bdev); bio->bi_iter.bi_sector = ec->start + dm_target_offset(ti, bio->bi_iter.bi_sector);
if (unlikely(bio_op(bio) == REQ_OP_FLUSH)) return DM_MAPIO_REMAPPED; /* * Only queue for bufio processing in case of partial or overlapping buffers * -or- * emulation with ebs == ubs aiming for tests of dm-bufio overhead. */ if (likely(__block_mod(bio->bi_iter.bi_sector, ec->u_bs) || __block_mod(bio_end_sector(bio), ec->u_bs) || ec->e_bs == ec->u_bs)) { spin_lock_irq(&ec->lock); bio_list_add(&ec->bios_in, bio); spin_unlock_irq(&ec->lock);
queue_work(ec->wq, &ec->ws);
return DM_MAPIO_SUBMITTED; }
/* Forget any buffer content relative to this direct backing device I/O. */ __ebs_forget_bio(ec, bio);
return DM_MAPIO_REMAPPED;}
static void ebs_postsuspend(struct dm_target *ti){ struct ebs_c *ec = ti->private; dm_bufio_client_reset(ec->bufio);}
static void ebs_status(struct dm_target *ti, status_type_t type, unsigned int status_flags, char *result, unsigned int maxlen){ struct ebs_c *ec = ti->private;
switch (type) { case STATUSTYPE_INFO: *result = '\0'; break; case STATUSTYPE_TABLE: snprintf(result, maxlen, ec->u_bs_set ? "%s %llu %u %u" : "%s %llu %u", ec->dev->name, (unsigned long long) ec->start, ec->e_bs, ec->u_bs); break; case STATUSTYPE_IMA: *result = '\0'; break; }}
static int ebs_prepare_ioctl(struct dm_target *ti, struct block_device **bdev, unsigned int cmd, unsigned long arg, bool *forward){ struct ebs_c *ec = ti->private; struct dm_dev *dev = ec->dev;
/* * Only pass ioctls through if the device sizes match exactly. */ *bdev = dev->bdev; return !!(ec->start || ti->len != bdev_nr_sectors(dev->bdev));}
static void ebs_io_hints(struct dm_target *ti, struct queue_limits *limits){ struct ebs_c *ec = ti->private;
limits->logical_block_size = to_bytes(ec->e_bs); limits->physical_block_size = to_bytes(ec->u_bs); limits->alignment_offset = limits->physical_block_size; limits->io_min = limits->logical_block_size;}
static int ebs_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data){ struct ebs_c *ec = ti->private;
return fn(ti, ec->dev, ec->start, ti->len, data);}
static struct target_type ebs_target = { .name = "ebs", .version = {1, 0, 1}, .features = 0, .module = THIS_MODULE, .ctr = ebs_ctr, .dtr = ebs_dtr, .map = ebs_map, .postsuspend = ebs_postsuspend, .status = ebs_status, .io_hints = ebs_io_hints, .prepare_ioctl = ebs_prepare_ioctl, .iterate_devices = ebs_iterate_devices,};module_dm(ebs);
MODULE_AUTHOR("Heinz Mauelshagen <dm-devel@lists.linux.dev>");MODULE_DESCRIPTION(DM_NAME " emulated block size target");MODULE_LICENSE("GPL");