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Diffstat (limited to 'module/zfs/zvol.c')
| -rw-r--r-- | module/zfs/zvol.c | 1337 |
1 files changed, 1337 insertions, 0 deletions
diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c new file mode 100644 index 000000000..6e9294292 --- /dev/null +++ b/module/zfs/zvol.c @@ -0,0 +1,1337 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ +/* + * Copyright (C) 2008-2010 Lawrence Livermore National Security, LLC. + * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). + * Rewritten for Linux by Brian Behlendorf <[email protected]>. + * LLNL-CODE-403049. + * + * ZFS volume emulation driver. + * + * Makes a DMU object look like a volume of arbitrary size, up to 2^64 bytes. + * Volumes are accessed through the symbolic links named: + * + * /dev/<pool_name>/<dataset_name> + * + * Volumes are persistent through reboot and module load. No user command + * needs to be run before opening and using a device. + */ + +#include <sys/dmu_traverse.h> +#include <sys/dsl_dataset.h> +#include <sys/dsl_prop.h> +#include <sys/zap.h> +#include <sys/zil_impl.h> +#include <sys/zio.h> +#include <sys/zfs_rlock.h> +#include <sys/zfs_znode.h> +#include <sys/zvol.h> + +unsigned int zvol_major = ZVOL_MAJOR; +unsigned int zvol_threads = 0; + +static taskq_t *zvol_taskq; +static kmutex_t zvol_state_lock; +static list_t zvol_state_list; +static char *zvol_tag = "zvol_tag"; + +/* + * The in-core state of each volume. + */ +typedef struct zvol_state { + char zv_name[DISK_NAME_LEN]; /* name */ + uint64_t zv_volsize; /* advertised space */ + uint64_t zv_volblocksize;/* volume block size */ + objset_t *zv_objset; /* objset handle */ + uint32_t zv_flags; /* ZVOL_* flags */ + uint32_t zv_open_count; /* open counts */ + uint32_t zv_changed; /* disk changed */ + zilog_t *zv_zilog; /* ZIL handle */ + znode_t zv_znode; /* for range locking */ + dmu_buf_t *zv_dbuf; /* bonus handle */ + dev_t zv_dev; /* device id */ + struct gendisk *zv_disk; /* generic disk */ + struct request_queue *zv_queue; /* request queue */ + spinlock_t zv_lock; /* request queue lock */ + list_node_t zv_next; /* next zvol_state_t linkage */ +} zvol_state_t; + +#define ZVOL_RDONLY 0x1 + +/* + * Find the next available range of ZVOL_MINORS minor numbers. The + * zvol_state_list is kept in ascending minor order so we simply need + * to scan the list for the first gap in the sequence. This allows us + * to recycle minor number as devices are created and removed. + */ +static int +zvol_find_minor(unsigned *minor) +{ + zvol_state_t *zv; + + *minor = 0; + ASSERT(MUTEX_HELD(&zvol_state_lock)); + for (zv = list_head(&zvol_state_list); zv != NULL; + zv = list_next(&zvol_state_list, zv), *minor += ZVOL_MINORS) { + if (MINOR(zv->zv_dev) != MINOR(*minor)) + break; + } + + /* All minors are in use */ + if (*minor >= (1 << MINORBITS)) + return ENXIO; + + return 0; +} + +/* + * Find a zvol_state_t given the full major+minor dev_t. + */ +static zvol_state_t * +zvol_find_by_dev(dev_t dev) +{ + zvol_state_t *zv; + + ASSERT(MUTEX_HELD(&zvol_state_lock)); + for (zv = list_head(&zvol_state_list); zv != NULL; + zv = list_next(&zvol_state_list, zv)) { + if (zv->zv_dev == dev) + return zv; + } + + return NULL; +} + +/* + * Find a zvol_state_t given the name provided at zvol_alloc() time. + */ +static zvol_state_t * +zvol_find_by_name(const char *name) +{ + zvol_state_t *zv; + + ASSERT(MUTEX_HELD(&zvol_state_lock)); + for (zv = list_head(&zvol_state_list); zv != NULL; + zv = list_next(&zvol_state_list, zv)) { + if (!strncmp(zv->zv_name, name, DISK_NAME_LEN)) + return zv; + } + + return NULL; +} + +/* + * ZFS_IOC_CREATE callback handles dmu zvol and zap object creation. + */ +void +zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx) +{ + zfs_creat_t *zct = arg; + nvlist_t *nvprops = zct->zct_props; + int error; + uint64_t volblocksize, volsize; + + VERIFY(nvlist_lookup_uint64(nvprops, + zfs_prop_to_name(ZFS_PROP_VOLSIZE), &volsize) == 0); + if (nvlist_lookup_uint64(nvprops, + zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &volblocksize) != 0) + volblocksize = zfs_prop_default_numeric(ZFS_PROP_VOLBLOCKSIZE); + + /* + * These properties must be removed from the list so the generic + * property setting step won't apply to them. + */ + VERIFY(nvlist_remove_all(nvprops, + zfs_prop_to_name(ZFS_PROP_VOLSIZE)) == 0); + (void) nvlist_remove_all(nvprops, + zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE)); + + error = dmu_object_claim(os, ZVOL_OBJ, DMU_OT_ZVOL, volblocksize, + DMU_OT_NONE, 0, tx); + ASSERT(error == 0); + + error = zap_create_claim(os, ZVOL_ZAP_OBJ, DMU_OT_ZVOL_PROP, + DMU_OT_NONE, 0, tx); + ASSERT(error == 0); + + error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize, tx); + ASSERT(error == 0); +} + +/* + * ZFS_IOC_OBJSET_STATS entry point. + */ +int +zvol_get_stats(objset_t *os, nvlist_t *nv) +{ + int error; + dmu_object_info_t *doi; + uint64_t val; + + error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &val); + if (error) + return (error); + + dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLSIZE, val); + doi = kmem_alloc(sizeof(dmu_object_info_t), KM_SLEEP); + error = dmu_object_info(os, ZVOL_OBJ, doi); + + if (error == 0) { + dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLBLOCKSIZE, + doi->doi_data_block_size); + } + + kmem_free(doi, sizeof(dmu_object_info_t)); + + return (error); +} + +/* + * Sanity check volume size. + */ +int +zvol_check_volsize(uint64_t volsize, uint64_t blocksize) +{ + if (volsize == 0) + return (EINVAL); + + if (volsize % blocksize != 0) + return (EINVAL); + +#ifdef _ILP32 + if (volsize - 1 > MAXOFFSET_T) + return (EOVERFLOW); +#endif + return (0); +} + +/* + * Ensure the zap is flushed then inform the VFS of the capacity change. + */ +static int +zvol_update_volsize(zvol_state_t *zv, uint64_t volsize) +{ + struct block_device *bdev; + dmu_tx_t *tx; + int error; + + ASSERT(MUTEX_HELD(&zvol_state_lock)); + + tx = dmu_tx_create(zv->zv_objset); + dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL); + error = dmu_tx_assign(tx, TXG_WAIT); + if (error) { + dmu_tx_abort(tx); + return (error); + } + + error = zap_update(zv->zv_objset, ZVOL_ZAP_OBJ, "size", 8, 1, + &volsize, tx); + dmu_tx_commit(tx); + + if (error) + return (error); + + error = dmu_free_long_range(zv->zv_objset, + ZVOL_OBJ, volsize, DMU_OBJECT_END); + if (error) + return (error); + + zv->zv_volsize = volsize; + zv->zv_changed = 1; + + bdev = bdget_disk(zv->zv_disk, 0); + if (!bdev) + return EIO; + + error = check_disk_change(bdev); + ASSERT3U(error, !=, 0); + bdput(bdev); + + return (0); +} + +/* + * Set ZFS_PROP_VOLSIZE set entry point. + */ +int +zvol_set_volsize(const char *name, uint64_t volsize) +{ + zvol_state_t *zv; + dmu_object_info_t *doi; + objset_t *os = NULL; + uint64_t readonly; + int error; + + mutex_enter(&zvol_state_lock); + + zv = zvol_find_by_name(name); + if (zv == NULL) { + error = ENXIO; + goto out; + } + + doi = kmem_alloc(sizeof(dmu_object_info_t), KM_SLEEP); + + error = dmu_objset_hold(name, FTAG, &os); + if (error) + goto out_doi; + + if ((error = dmu_object_info(os, ZVOL_OBJ, doi)) != 0 || + (error = zvol_check_volsize(volsize,doi->doi_data_block_size)) != 0) + goto out_doi; + + VERIFY(dsl_prop_get_integer(name, "readonly", &readonly, NULL) == 0); + if (readonly) { + error = EROFS; + goto out_doi; + } + + if (get_disk_ro(zv->zv_disk) || (zv->zv_flags & ZVOL_RDONLY)) { + error = EROFS; + goto out_doi; + } + + error = zvol_update_volsize(zv, volsize); +out_doi: + kmem_free(doi, sizeof(dmu_object_info_t)); +out: + if (os) + dmu_objset_rele(os, FTAG); + + mutex_exit(&zvol_state_lock); + + return (error); +} + +/* + * Sanity check volume block size. + */ +int +zvol_check_volblocksize(uint64_t volblocksize) +{ + if (volblocksize < SPA_MINBLOCKSIZE || + volblocksize > SPA_MAXBLOCKSIZE || + !ISP2(volblocksize)) + return (EDOM); + + return (0); +} + +/* + * Set ZFS_PROP_VOLBLOCKSIZE set entry point. + */ +int +zvol_set_volblocksize(const char *name, uint64_t volblocksize) +{ + zvol_state_t *zv; + dmu_tx_t *tx; + int error; + + mutex_enter(&zvol_state_lock); + + zv = zvol_find_by_name(name); + if (zv == NULL) { + error = ENXIO; + goto out; + } + + if (get_disk_ro(zv->zv_disk) || (zv->zv_flags & ZVOL_RDONLY)) { + error = EROFS; + goto out; + } + + tx = dmu_tx_create(zv->zv_objset); + dmu_tx_hold_bonus(tx, ZVOL_OBJ); + error = dmu_tx_assign(tx, TXG_WAIT); + if (error) { + dmu_tx_abort(tx); + } else { + error = dmu_object_set_blocksize(zv->zv_objset, ZVOL_OBJ, + volblocksize, 0, tx); + if (error == ENOTSUP) + error = EBUSY; + dmu_tx_commit(tx); + if (error == 0) + zv->zv_volblocksize = volblocksize; + } +out: + mutex_exit(&zvol_state_lock); + + return (error); +} + +/* + * Replay a TX_WRITE ZIL transaction that didn't get committed + * after a system failure + */ +static int +zvol_replay_write(zvol_state_t *zv, lr_write_t *lr, boolean_t byteswap) +{ + objset_t *os = zv->zv_objset; + char *data = (char *)(lr + 1); /* data follows lr_write_t */ + uint64_t off = lr->lr_offset; + uint64_t len = lr->lr_length; + dmu_tx_t *tx; + int error; + + if (byteswap) + byteswap_uint64_array(lr, sizeof (*lr)); + + tx = dmu_tx_create(os); + dmu_tx_hold_write(tx, ZVOL_OBJ, off, len); + error = dmu_tx_assign(tx, TXG_WAIT); + if (error) { + dmu_tx_abort(tx); + } else { + dmu_write(os, ZVOL_OBJ, off, len, data, tx); + dmu_tx_commit(tx); + } + + return (error); +} + +static int +zvol_replay_err(zvol_state_t *zv, lr_t *lr, boolean_t byteswap) +{ + return (ENOTSUP); +} + +/* + * Callback vectors for replaying records. + * Only TX_WRITE is needed for zvol. + */ +zil_replay_func_t *zvol_replay_vector[TX_MAX_TYPE] = { + (zil_replay_func_t *)zvol_replay_err, /* no such transaction type */ + (zil_replay_func_t *)zvol_replay_err, /* TX_CREATE */ + (zil_replay_func_t *)zvol_replay_err, /* TX_MKDIR */ + (zil_replay_func_t *)zvol_replay_err, /* TX_MKXATTR */ + (zil_replay_func_t *)zvol_replay_err, /* TX_SYMLINK */ + (zil_replay_func_t *)zvol_replay_err, /* TX_REMOVE */ + (zil_replay_func_t *)zvol_replay_err, /* TX_RMDIR */ + (zil_replay_func_t *)zvol_replay_err, /* TX_LINK */ + (zil_replay_func_t *)zvol_replay_err, /* TX_RENAME */ + (zil_replay_func_t *)zvol_replay_write, /* TX_WRITE */ + (zil_replay_func_t *)zvol_replay_err, /* TX_TRUNCATE */ + (zil_replay_func_t *)zvol_replay_err, /* TX_SETATTR */ + (zil_replay_func_t *)zvol_replay_err, /* TX_ACL */ +}; + +/* + * zvol_log_write() handles synchronous writes using TX_WRITE ZIL transactions. + * + * We store data in the log buffers if it's small enough. + * Otherwise we will later flush the data out via dmu_sync(). + */ +ssize_t zvol_immediate_write_sz = 32768; + +static void +zvol_log_write(zvol_state_t *zv, dmu_tx_t *tx, + uint64_t offset, uint64_t size, int sync) +{ + uint32_t blocksize = zv->zv_volblocksize; + zilog_t *zilog = zv->zv_zilog; + boolean_t slogging; + + if (zil_replaying(zilog, tx)) + return; + + slogging = spa_has_slogs(zilog->zl_spa); + + while (size) { + itx_t *itx; + lr_write_t *lr; + ssize_t len; + itx_wr_state_t write_state; + + /* + * Unlike zfs_log_write() we can be called with + * up to DMU_MAX_ACCESS/2 (5MB) writes. + */ + if (blocksize > zvol_immediate_write_sz && !slogging && + size >= blocksize && offset % blocksize == 0) { + write_state = WR_INDIRECT; /* uses dmu_sync */ + len = blocksize; + } else if (sync) { + write_state = WR_COPIED; + len = MIN(ZIL_MAX_LOG_DATA, size); + } else { + write_state = WR_NEED_COPY; + len = MIN(ZIL_MAX_LOG_DATA, size); + } + + itx = zil_itx_create(TX_WRITE, sizeof (*lr) + + (write_state == WR_COPIED ? len : 0)); + lr = (lr_write_t *)&itx->itx_lr; + if (write_state == WR_COPIED && dmu_read(zv->zv_objset, + ZVOL_OBJ, offset, len, lr+1, DMU_READ_NO_PREFETCH) != 0) { + zil_itx_destroy(itx); + itx = zil_itx_create(TX_WRITE, sizeof (*lr)); + lr = (lr_write_t *)&itx->itx_lr; + write_state = WR_NEED_COPY; + } + + itx->itx_wr_state = write_state; + if (write_state == WR_NEED_COPY) + itx->itx_sod += len; + lr->lr_foid = ZVOL_OBJ; + lr->lr_offset = offset; + lr->lr_length = len; + lr->lr_blkoff = 0; + BP_ZERO(&lr->lr_blkptr); + + itx->itx_private = zv; + itx->itx_sync = sync; + + (void) zil_itx_assign(zilog, itx, tx); + + offset += len; + size -= len; + } +} + +/* + * Common write path running under the zvol taskq context. This function + * is responsible for copying the request structure data in to the DMU and + * signaling the request queue with the result of the copy. + */ +static void +zvol_write(void *arg) +{ + struct request *req = (struct request *)arg; + struct request_queue *q = req->q; + zvol_state_t *zv = q->queuedata; + uint64_t offset = blk_rq_pos(req) << 9; + uint64_t size = blk_rq_bytes(req); + int error = 0; + dmu_tx_t *tx; + rl_t *rl; + + rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_WRITER); + + tx = dmu_tx_create(zv->zv_objset); + dmu_tx_hold_write(tx, ZVOL_OBJ, offset, size); + + /* This will only fail for ENOSPC */ + error = dmu_tx_assign(tx, TXG_WAIT); + if (error) { + dmu_tx_abort(tx); + zfs_range_unlock(rl); + blk_end_request(req, -error, size); + return; + } + + error = dmu_write_req(zv->zv_objset, ZVOL_OBJ, req, tx); + if (error == 0) + zvol_log_write(zv, tx, offset, size, rq_is_sync(req)); + + dmu_tx_commit(tx); + zfs_range_unlock(rl); + + if (rq_is_sync(req)) + zil_commit(zv->zv_zilog, ZVOL_OBJ); + + blk_end_request(req, -error, size); +} + +/* + * Common read path running under the zvol taskq context. This function + * is responsible for copying the requested data out of the DMU and in to + * a linux request structure. It then must signal the request queue with + * an error code describing the result of the copy. + */ +static void +zvol_read(void *arg) +{ + struct request *req = (struct request *)arg; + struct request_queue *q = req->q; + zvol_state_t *zv = q->queuedata; + uint64_t offset = blk_rq_pos(req) << 9; + uint64_t size = blk_rq_bytes(req); + int error; + rl_t *rl; + + rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_READER); + + error = dmu_read_req(zv->zv_objset, ZVOL_OBJ, req); + + zfs_range_unlock(rl); + + /* convert checksum errors into IO errors */ + if (error == ECKSUM) + error = EIO; + + blk_end_request(req, -error, size); +} + +/* + * Request will be added back to the request queue and retried if + * it cannot be immediately dispatched to the taskq for handling + */ +static inline void +zvol_dispatch(task_func_t func, struct request *req) +{ + if (!taskq_dispatch(zvol_taskq, func, (void *)req, TQ_NOSLEEP)) + blk_requeue_request(req->q, req); +} + +/* + * Common request path. Rather than registering a custom make_request() + * function we use the generic Linux version. This is done because it allows + * us to easily merge read requests which would otherwise we performed + * synchronously by the DMU. This is less critical in write case where the + * DMU will perform the correct merging within a transaction group. Using + * the generic make_request() also let's use leverage the fact that the + * elevator with ensure correct ordering in regards to barrior IOs. On + * the downside it means that in the write case we end up doing request + * merging twice once in the elevator and once in the DMU. + * + * The request handler is called under a spin lock so all the real work + * is handed off to be done in the context of the zvol taskq. This function + * simply performs basic request sanity checking and hands off the request. + */ +static void +zvol_request(struct request_queue *q) +{ + zvol_state_t *zv = q->queuedata; + struct request *req; + unsigned int size; + + while ((req = blk_fetch_request(q)) != NULL) { + size = blk_rq_bytes(req); + + if (blk_rq_pos(req) + blk_rq_sectors(req) > + get_capacity(zv->zv_disk)) { + printk(KERN_INFO + "%s: bad access: block=%llu, count=%lu\n", + req->rq_disk->disk_name, + (long long unsigned)blk_rq_pos(req), + (long unsigned)blk_rq_sectors(req)); + __blk_end_request(req, -EIO, size); + continue; + } + + if (!blk_fs_request(req)) { + printk(KERN_INFO "%s: non-fs cmd\n", + req->rq_disk->disk_name); + __blk_end_request(req, -EIO, size); + continue; + } + + switch (rq_data_dir(req)) { + case READ: + zvol_dispatch(zvol_read, req); + break; + case WRITE: + if (unlikely(get_disk_ro(zv->zv_disk)) || + unlikely(zv->zv_flags & ZVOL_RDONLY)) { + __blk_end_request(req, -EROFS, size); + break; + } + + zvol_dispatch(zvol_write, req); + break; + default: + printk(KERN_INFO "%s: unknown cmd: %d\n", + req->rq_disk->disk_name, (int)rq_data_dir(req)); + __blk_end_request(req, -EIO, size); + break; + } + } +} + +static void +zvol_get_done(zgd_t *zgd, int error) +{ + if (zgd->zgd_db) + dmu_buf_rele(zgd->zgd_db, zgd); + + zfs_range_unlock(zgd->zgd_rl); + + if (error == 0 && zgd->zgd_bp) + zil_add_block(zgd->zgd_zilog, zgd->zgd_bp); + + kmem_free(zgd, sizeof (zgd_t)); +} + +/* + * Get data to generate a TX_WRITE intent log record. + */ +static int +zvol_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio) +{ + zvol_state_t *zv = arg; + objset_t *os = zv->zv_objset; + uint64_t offset = lr->lr_offset; + uint64_t size = lr->lr_length; + dmu_buf_t *db; + zgd_t *zgd; + int error; + + ASSERT(zio != NULL); + ASSERT(size != 0); + + zgd = (zgd_t *)kmem_zalloc(sizeof (zgd_t), KM_SLEEP); + zgd->zgd_zilog = zv->zv_zilog; + zgd->zgd_rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_READER); + + /* + * Write records come in two flavors: immediate and indirect. + * For small writes it's cheaper to store the data with the + * log record (immediate); for large writes it's cheaper to + * sync the data and get a pointer to it (indirect) so that + * we don't have to write the data twice. + */ + if (buf != NULL) { /* immediate write */ + error = dmu_read(os, ZVOL_OBJ, offset, size, buf, + DMU_READ_NO_PREFETCH); + } else { + size = zv->zv_volblocksize; + offset = P2ALIGN_TYPED(offset, size, uint64_t); + error = dmu_buf_hold(os, ZVOL_OBJ, offset, zgd, &db, + DMU_READ_NO_PREFETCH); + if (error == 0) { + zgd->zgd_db = db; + zgd->zgd_bp = &lr->lr_blkptr; + + ASSERT(db != NULL); + ASSERT(db->db_offset == offset); + ASSERT(db->db_size == size); + + error = dmu_sync(zio, lr->lr_common.lrc_txg, + zvol_get_done, zgd); + + if (error == 0) + return (0); + } + } + + zvol_get_done(zgd, error); + + return (error); +} + +/* + * The zvol_state_t's are inserted in increasing MINOR(dev_t) order. + */ +static void +zvol_insert(zvol_state_t *zv_insert) +{ + zvol_state_t *zv = NULL; + + ASSERT(MUTEX_HELD(&zvol_state_lock)); + ASSERT3U(MINOR(zv_insert->zv_dev) & ZVOL_MINOR_MASK, ==, 0); + for (zv = list_head(&zvol_state_list); zv != NULL; + zv = list_next(&zvol_state_list, zv)) { + if (MINOR(zv->zv_dev) > MINOR(zv_insert->zv_dev)) + break; + } + + list_insert_before(&zvol_state_list, zv, zv_insert); +} + +/* + * Simply remove the zvol from to list of zvols. + */ +static void +zvol_remove(zvol_state_t *zv_remove) +{ + ASSERT(MUTEX_HELD(&zvol_state_lock)); + list_remove(&zvol_state_list, zv_remove); +} + +static int +zvol_first_open(zvol_state_t *zv) +{ + objset_t *os; + uint64_t volsize; + int error; + uint64_t ro; + + /* lie and say we're read-only */ + error = dmu_objset_own(zv->zv_name, DMU_OST_ZVOL, 1, zvol_tag, &os); + if (error) + return (-error); + + error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize); + if (error) { + dmu_objset_disown(os, zvol_tag); + return (-error); + } + + zv->zv_objset = os; + error = dmu_bonus_hold(os, ZVOL_OBJ, zvol_tag, &zv->zv_dbuf); + if (error) { + dmu_objset_disown(os, zvol_tag); + return (-error); + } + + set_capacity(zv->zv_disk, volsize >> 9); + zv->zv_volsize = volsize; + zv->zv_zilog = zil_open(os, zvol_get_data); + + VERIFY(dsl_prop_get_integer(zv->zv_name, "readonly", &ro, NULL) == 0); + if (ro || dmu_objset_is_snapshot(os)) { + set_disk_ro(zv->zv_disk, 1); + zv->zv_flags |= ZVOL_RDONLY; + } else { + set_disk_ro(zv->zv_disk, 0); + zv->zv_flags &= ~ZVOL_RDONLY; + } + + return (-error); +} + +static void +zvol_last_close(zvol_state_t *zv) +{ + zil_close(zv->zv_zilog); + zv->zv_zilog = NULL; + dmu_buf_rele(zv->zv_dbuf, zvol_tag); + zv->zv_dbuf = NULL; + dmu_objset_disown(zv->zv_objset, zvol_tag); + zv->zv_objset = NULL; +} + +static int +zvol_open(struct block_device *bdev, fmode_t flag) +{ + zvol_state_t *zv = bdev->bd_disk->private_data; + int error = 0, drop_mutex = 0; + + /* + * If the caller is already holding the mutex do not take it + * again, this will happen as part of zvol_create_minor(). + * Once add_disk() is called the device is live and the kernel + * will attempt to open it to read the partition information. + */ + if (!mutex_owned(&zvol_state_lock)) { + mutex_enter(&zvol_state_lock); + drop_mutex = 1; + } + + ASSERT3P(zv, !=, NULL); + + if (zv->zv_open_count == 0) { + error = zvol_first_open(zv); + if (error) + goto out_mutex; + } + + if ((flag & FMODE_WRITE) && + (get_disk_ro(zv->zv_disk) || (zv->zv_flags & ZVOL_RDONLY))) { + error = -EROFS; + goto out_open_count; + } + + zv->zv_open_count++; + +out_open_count: + if (zv->zv_open_count == 0) + zvol_last_close(zv); + +out_mutex: + if (drop_mutex) + mutex_exit(&zvol_state_lock); + + check_disk_change(bdev); + + return (error); +} + +static int +zvol_release(struct gendisk *disk, fmode_t mode) +{ + zvol_state_t *zv = disk->private_data; + int drop_mutex = 0; + + if (!mutex_owned(&zvol_state_lock)) { + mutex_enter(&zvol_state_lock); + drop_mutex = 1; + } + + ASSERT3P(zv, !=, NULL); + ASSERT3U(zv->zv_open_count, >, 0); + zv->zv_open_count--; + if (zv->zv_open_count == 0) + zvol_last_close(zv); + + if (drop_mutex) + mutex_exit(&zvol_state_lock); + + return (0); +} + +static int +zvol_ioctl(struct block_device *bdev, fmode_t mode, + unsigned int cmd, unsigned long arg) +{ + zvol_state_t *zv = bdev->bd_disk->private_data; + int error = 0; + + if (zv == NULL) + return (-ENXIO); + + switch (cmd) { + case BLKFLSBUF: + zil_commit(zv->zv_zilog, ZVOL_OBJ); + break; + + default: + error = -ENOTTY; + break; + + } + + return (error); +} + +#ifdef CONFIG_COMPAT +static int +zvol_compat_ioctl(struct block_device *bdev, fmode_t mode, + unsigned cmd, unsigned long arg) +{ + return zvol_ioctl(bdev, mode, cmd, arg); +} +#else +#define zvol_compat_ioctl NULL +#endif + +static int zvol_media_changed(struct gendisk *disk) +{ + zvol_state_t *zv = disk->private_data; + + return zv->zv_changed; +} + +static int zvol_revalidate_disk(struct gendisk *disk) +{ + zvol_state_t *zv = disk->private_data; + + zv->zv_changed = 0; + set_capacity(zv->zv_disk, zv->zv_volsize >> 9); + + return 0; +} + +/* + * Provide a simple virtual geometry for legacy compatibility. For devices + * smaller than 1 MiB a small head and sector count is used to allow very + * tiny devices. For devices over 1 Mib a standard head and sector count + * is used to keep the cylinders count reasonable. + */ +static int +zvol_getgeo(struct block_device *bdev, struct hd_geometry *geo) +{ + zvol_state_t *zv = bdev->bd_disk->private_data; + sector_t sectors = get_capacity(zv->zv_disk); + + if (sectors > 2048) { + geo->heads = 16; + geo->sectors = 63; + } else { + geo->heads = 2; + geo->sectors = 4; + } + + geo->start = 0; + geo->cylinders = sectors / (geo->heads * geo->sectors); + + return 0; +} + +static struct kobject * +zvol_probe(dev_t dev, int *part, void *arg) +{ + zvol_state_t *zv; + struct kobject *kobj; + + mutex_enter(&zvol_state_lock); + zv = zvol_find_by_dev(dev); + kobj = zv ? get_disk(zv->zv_disk) : ERR_PTR(-ENOENT); + mutex_exit(&zvol_state_lock); + + return kobj; +} + +#ifdef HAVE_BDEV_BLOCK_DEVICE_OPERATIONS +static struct block_device_operations zvol_ops = { + .open = zvol_open, + .release = zvol_release, + .ioctl = zvol_ioctl, + .compat_ioctl = zvol_compat_ioctl, + .media_changed = zvol_media_changed, + .revalidate_disk = zvol_revalidate_disk, + .getgeo = zvol_getgeo, + .owner = THIS_MODULE, +}; + +#else /* HAVE_BDEV_BLOCK_DEVICE_OPERATIONS */ + +static int +zvol_open_by_inode(struct inode *inode, struct file *file) +{ + return zvol_open(inode->i_bdev, file->f_mode); +} + +static int +zvol_release_by_inode(struct inode *inode, struct file *file) +{ + return zvol_release(inode->i_bdev->bd_disk, file->f_mode); +} + +static int +zvol_ioctl_by_inode(struct inode *inode, struct file *file, + unsigned int cmd, unsigned long arg) +{ + return zvol_ioctl(inode->i_bdev, file->f_mode, cmd, arg); +} + +# ifdef CONFIG_COMPAT +static long +zvol_compat_ioctl_by_inode(struct file *file, + unsigned int cmd, unsigned long arg) +{ + return zvol_compat_ioctl(file->f_dentry->d_inode->i_bdev, + file->f_mode, cmd, arg); +} +# else +# define zvol_compat_ioctl_by_inode NULL +# endif + +static struct block_device_operations zvol_ops = { + .open = zvol_open_by_inode, + .release = zvol_release_by_inode, + .ioctl = zvol_ioctl_by_inode, + .compat_ioctl = zvol_compat_ioctl_by_inode, + .media_changed = zvol_media_changed, + .revalidate_disk = zvol_revalidate_disk, + .getgeo = zvol_getgeo, + .owner = THIS_MODULE, +}; +#endif /* HAVE_BDEV_BLOCK_DEVICE_OPERATIONS */ + +/* + * Allocate memory for a new zvol_state_t and setup the required + * request queue and generic disk structures for the block device. + */ +static zvol_state_t * +zvol_alloc(dev_t dev, const char *name) +{ + zvol_state_t *zv; + + zv = kmem_zalloc(sizeof (zvol_state_t), KM_SLEEP); + if (zv == NULL) + goto out; + + zv->zv_queue = blk_init_queue(zvol_request, &zv->zv_lock); + if (zv->zv_queue == NULL) + goto out_kmem; + + zv->zv_disk = alloc_disk(ZVOL_MINORS); + if (zv->zv_disk == NULL) + goto out_queue; + + zv->zv_queue->queuedata = zv; + zv->zv_dev = dev; + zv->zv_open_count = 0; + strlcpy(zv->zv_name, name, DISK_NAME_LEN); + + mutex_init(&zv->zv_znode.z_range_lock, NULL, MUTEX_DEFAULT, NULL); + avl_create(&zv->zv_znode.z_range_avl, zfs_range_compare, + sizeof (rl_t), offsetof(rl_t, r_node)); + spin_lock_init(&zv->zv_lock); + list_link_init(&zv->zv_next); + + zv->zv_disk->major = zvol_major; + zv->zv_disk->first_minor = (dev & MINORMASK); + zv->zv_disk->fops = &zvol_ops; + zv->zv_disk->private_data = zv; + zv->zv_disk->queue = zv->zv_queue; + snprintf(zv->zv_disk->disk_name, DISK_NAME_LEN, "%s", name); + + return zv; + +out_queue: + blk_cleanup_queue(zv->zv_queue); +out_kmem: + kmem_free(zv, sizeof (zvol_state_t)); +out: + return NULL; +} + +/* + * Cleanup then free a zvol_state_t which was created by zvol_alloc(). + */ +static void +zvol_free(zvol_state_t *zv) +{ + avl_destroy(&zv->zv_znode.z_range_avl); + mutex_destroy(&zv->zv_znode.z_range_lock); + + del_gendisk(zv->zv_disk); + blk_cleanup_queue(zv->zv_queue); + put_disk(zv->zv_disk); + + kmem_free(zv, sizeof (zvol_state_t)); +} + +static int +__zvol_create_minor(const char *name) +{ + zvol_state_t *zv; + objset_t *os; + dmu_object_info_t *doi; + uint64_t volsize; + unsigned minor = 0; + int error = 0; + + ASSERT(MUTEX_HELD(&zvol_state_lock)); + + zv = zvol_find_by_name(name); + if (zv) { + error = EEXIST; + goto out; + } + + doi = kmem_alloc(sizeof(dmu_object_info_t), KM_SLEEP); + + error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, zvol_tag, &os); + if (error) + goto out_doi; + + error = dmu_object_info(os, ZVOL_OBJ, doi); + if (error) + goto out_dmu_objset_disown; + + error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize); + if (error) + goto out_dmu_objset_disown; + + error = zvol_find_minor(&minor); + if (error) + goto out_dmu_objset_disown; + + zv = zvol_alloc(MKDEV(zvol_major, minor), name); + if (zv == NULL) { + error = EAGAIN; + goto out_dmu_objset_disown; + } + + if (dmu_objset_is_snapshot(os)) + zv->zv_flags |= ZVOL_RDONLY; + + zv->zv_volblocksize = doi->doi_data_block_size; + zv->zv_volsize = volsize; + zv->zv_objset = os; + + set_capacity(zv->zv_disk, zv->zv_volsize >> 9); + + if (zil_replay_disable) + zil_destroy(dmu_objset_zil(os), B_FALSE); + else + zil_replay(os, zv, zvol_replay_vector); + +out_dmu_objset_disown: + dmu_objset_disown(os, zvol_tag); + zv->zv_objset = NULL; +out_doi: + kmem_free(doi, sizeof(dmu_object_info_t)); +out: + + if (error == 0) { + zvol_insert(zv); + add_disk(zv->zv_disk); + } + + return (error); +} + +/* + * Create a block device minor node and setup the linkage between it + * and the specified volume. Once this function returns the block + * device is live and ready for use. + */ +int +zvol_create_minor(const char *name) +{ + int error; + + mutex_enter(&zvol_state_lock); + error = __zvol_create_minor(name); + mutex_exit(&zvol_state_lock); + + return (error); +} + +static int +__zvol_remove_minor(const char *name) +{ + zvol_state_t *zv; + + ASSERT(MUTEX_HELD(&zvol_state_lock)); + + zv = zvol_find_by_name(name); + if (zv == NULL) + return (ENXIO); + + if (zv->zv_open_count > 0) + return (EBUSY); + + zvol_remove(zv); + zvol_free(zv); + + return (0); +} + +/* + * Remove a block device minor node for the specified volume. + */ +int +zvol_remove_minor(const char *name) +{ + int error; + + mutex_enter(&zvol_state_lock); + error = __zvol_remove_minor(name); + mutex_exit(&zvol_state_lock); + + return (error); +} + +static int +zvol_create_minors_cb(spa_t *spa, uint64_t dsobj, + const char *dsname, void *arg) +{ + if (strchr(dsname, '/') == NULL) + return 0; + + return __zvol_create_minor(dsname); +} + +/* + * Create minors for specified pool, if pool is NULL create minors + * for all available pools. + */ +int +zvol_create_minors(const char *pool) +{ + spa_t *spa = NULL; + int error = 0; + + mutex_enter(&zvol_state_lock); + if (pool) { + error = dmu_objset_find_spa(NULL, pool, zvol_create_minors_cb, + NULL, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS); + } else { + mutex_enter(&spa_namespace_lock); + while ((spa = spa_next(spa)) != NULL) { + error = dmu_objset_find_spa(NULL, + spa_name(spa), zvol_create_minors_cb, NULL, + DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS); + if (error) + break; + } + mutex_exit(&spa_namespace_lock); + } + mutex_exit(&zvol_state_lock); + + return error; +} + +/* + * Remove minors for specified pool, if pool is NULL remove all minors. + */ +void +zvol_remove_minors(const char *pool) +{ + zvol_state_t *zv, *zv_next; + char *str; + + str = kmem_zalloc(DISK_NAME_LEN, KM_SLEEP); + if (pool) { + (void) strncpy(str, pool, strlen(pool)); + (void) strcat(str, "/"); + } + + mutex_enter(&zvol_state_lock); + for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) { + zv_next = list_next(&zvol_state_list, zv); + + if (pool == NULL || !strncmp(str, zv->zv_name, strlen(str))) { + zvol_remove(zv); + zvol_free(zv); + } + } + mutex_exit(&zvol_state_lock); + kmem_free(str, DISK_NAME_LEN); +} + +int +zvol_init(void) +{ + int error; + + if (!zvol_threads) + zvol_threads = num_online_cpus(); + + zvol_taskq = taskq_create(ZVOL_DRIVER, zvol_threads, maxclsyspri, + zvol_threads, INT_MAX, TASKQ_PREPOPULATE); + if (zvol_taskq == NULL) { + printk(KERN_INFO "ZFS: taskq_create() failed\n"); + return (-ENOMEM); + } + + error = register_blkdev(zvol_major, ZVOL_DRIVER); + if (error) { + printk(KERN_INFO "ZFS: register_blkdev() failed %d\n", error); + taskq_destroy(zvol_taskq); + return (error); + } + + blk_register_region(MKDEV(zvol_major, 0), 1UL << MINORBITS, + THIS_MODULE, zvol_probe, NULL, NULL); + + mutex_init(&zvol_state_lock, NULL, MUTEX_DEFAULT, NULL); + list_create(&zvol_state_list, sizeof (zvol_state_t), + offsetof(zvol_state_t, zv_next)); + + (void) zvol_create_minors(NULL); + + return (0); +} + +void +zvol_fini(void) +{ + zvol_remove_minors(NULL); + blk_unregister_region(MKDEV(zvol_major, 0), 1UL << MINORBITS); + unregister_blkdev(zvol_major, ZVOL_DRIVER); + taskq_destroy(zvol_taskq); + mutex_destroy(&zvol_state_lock); + list_destroy(&zvol_state_list); +} + +module_param(zvol_major, uint, 0); +MODULE_PARM_DESC(zvol_major, "Major number for zvol device"); + +module_param(zvol_threads, uint, 0); +MODULE_PARM_DESC(zvol_threads, "Number of threads for zvol device"); |