WIP FPC-III support

[linux/fpc-iii.git] / drivers / scsi / cxlflash / vlun.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * CXL Flash Device Driver
 *
 * Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
 *             Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
 *
 * Copyright (C) 2015 IBM Corporation
 */

#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/syscalls.h>
#include <asm/unaligned.h>
#include <asm/bitsperlong.h>

#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <uapi/scsi/cxlflash_ioctl.h>

#include "sislite.h"
#include "common.h"
#include "vlun.h"
#include "superpipe.h"

/**
 * marshal_virt_to_resize() - translate uvirtual to resize structure
 * @virt:       Source structure from which to translate/copy.
 * @resize:     Destination structure for the translate/copy.
 */
static void marshal_virt_to_resize(struct dk_cxlflash_uvirtual *virt,
                                   struct dk_cxlflash_resize *resize)
{
        resize->hdr = virt->hdr;
        resize->context_id = virt->context_id;
        resize->rsrc_handle = virt->rsrc_handle;
        resize->req_size = virt->lun_size;
        resize->last_lba = virt->last_lba;
}

/**
 * marshal_clone_to_rele() - translate clone to release structure
 * @clone:      Source structure from which to translate/copy.
 * @rele:       Destination structure for the translate/copy.
 */
static void marshal_clone_to_rele(struct dk_cxlflash_clone *clone,
                                  struct dk_cxlflash_release *release)
{
        release->hdr = clone->hdr;
        release->context_id = clone->context_id_dst;
}

/**
 * ba_init() - initializes a block allocator
 * @ba_lun:     Block allocator to initialize.
 *
 * Return: 0 on success, -errno on failure
 */
static int ba_init(struct ba_lun *ba_lun)
{
        struct ba_lun_info *bali = NULL;
        int lun_size_au = 0, i = 0;
        int last_word_underflow = 0;
        u64 *lam;

        pr_debug("%s: Initializing LUN: lun_id=%016llx "
                 "ba_lun->lsize=%lx ba_lun->au_size=%lX\n",
                __func__, ba_lun->lun_id, ba_lun->lsize, ba_lun->au_size);

        /* Calculate bit map size */
        lun_size_au = ba_lun->lsize / ba_lun->au_size;
        if (lun_size_au == 0) {
                pr_debug("%s: Requested LUN size of 0!\n", __func__);
                return -EINVAL;
        }

        /* Allocate lun information container */
        bali = kzalloc(sizeof(struct ba_lun_info), GFP_KERNEL);
        if (unlikely(!bali)) {
                pr_err("%s: Failed to allocate lun_info lun_id=%016llx\n",
                       __func__, ba_lun->lun_id);
                return -ENOMEM;
        }

        bali->total_aus = lun_size_au;
        bali->lun_bmap_size = lun_size_au / BITS_PER_LONG;

        if (lun_size_au % BITS_PER_LONG)
                bali->lun_bmap_size++;

        /* Allocate bitmap space */
        bali->lun_alloc_map = kzalloc((bali->lun_bmap_size * sizeof(u64)),
                                      GFP_KERNEL);
        if (unlikely(!bali->lun_alloc_map)) {
                pr_err("%s: Failed to allocate lun allocation map: "
                       "lun_id=%016llx\n", __func__, ba_lun->lun_id);
                kfree(bali);
                return -ENOMEM;
        }

        /* Initialize the bit map size and set all bits to '1' */
        bali->free_aun_cnt = lun_size_au;

        for (i = 0; i < bali->lun_bmap_size; i++)
                bali->lun_alloc_map[i] = 0xFFFFFFFFFFFFFFFFULL;

        /* If the last word not fully utilized, mark extra bits as allocated */
        last_word_underflow = (bali->lun_bmap_size * BITS_PER_LONG);
        last_word_underflow -= bali->free_aun_cnt;
        if (last_word_underflow > 0) {
                lam = &bali->lun_alloc_map[bali->lun_bmap_size - 1];
                for (i = (HIBIT - last_word_underflow + 1);
                     i < BITS_PER_LONG;
                     i++)
                        clear_bit(i, (ulong *)lam);
        }

        /* Initialize high elevator index, low/curr already at 0 from kzalloc */
        bali->free_high_idx = bali->lun_bmap_size;

        /* Allocate clone map */
        bali->aun_clone_map = kzalloc((bali->total_aus * sizeof(u8)),
                                      GFP_KERNEL);
        if (unlikely(!bali->aun_clone_map)) {
                pr_err("%s: Failed to allocate clone map: lun_id=%016llx\n",
                       __func__, ba_lun->lun_id);
                kfree(bali->lun_alloc_map);
                kfree(bali);
                return -ENOMEM;
        }

        /* Pass the allocated LUN info as a handle to the user */
        ba_lun->ba_lun_handle = bali;

        pr_debug("%s: Successfully initialized the LUN: "
                 "lun_id=%016llx bitmap size=%x, free_aun_cnt=%llx\n",
                __func__, ba_lun->lun_id, bali->lun_bmap_size,
                bali->free_aun_cnt);
        return 0;
}

/**
 * find_free_range() - locates a free bit within the block allocator
 * @low:        First word in block allocator to start search.
 * @high:       Last word in block allocator to search.
 * @bali:       LUN information structure owning the block allocator to search.
 * @bit_word:   Passes back the word in the block allocator owning the free bit.
 *
 * Return: The bit position within the passed back word, -1 on failure
 */
static int find_free_range(u32 low,
                           u32 high,
                           struct ba_lun_info *bali, int *bit_word)
{
        int i;
        u64 bit_pos = -1;
        ulong *lam, num_bits;

        for (i = low; i < high; i++)
                if (bali->lun_alloc_map[i] != 0) {
                        lam = (ulong *)&bali->lun_alloc_map[i];
                        num_bits = (sizeof(*lam) * BITS_PER_BYTE);
                        bit_pos = find_first_bit(lam, num_bits);

                        pr_devel("%s: Found free bit %llu in LUN "
                                 "map entry %016llx at bitmap index = %d\n",
                                 __func__, bit_pos, bali->lun_alloc_map[i], i);

                        *bit_word = i;
                        bali->free_aun_cnt--;
                        clear_bit(bit_pos, lam);
                        break;
                }

        return bit_pos;
}

/**
 * ba_alloc() - allocates a block from the block allocator
 * @ba_lun:     Block allocator from which to allocate a block.
 *
 * Return: The allocated block, -1 on failure
 */
static u64 ba_alloc(struct ba_lun *ba_lun)
{
        u64 bit_pos = -1;
        int bit_word = 0;
        struct ba_lun_info *bali = NULL;

        bali = ba_lun->ba_lun_handle;

        pr_debug("%s: Received block allocation request: "
                 "lun_id=%016llx free_aun_cnt=%llx\n",
                 __func__, ba_lun->lun_id, bali->free_aun_cnt);

        if (bali->free_aun_cnt == 0) {
                pr_debug("%s: No space left on LUN: lun_id=%016llx\n",
                         __func__, ba_lun->lun_id);
                return -1ULL;
        }

        /* Search to find a free entry, curr->high then low->curr */
        bit_pos = find_free_range(bali->free_curr_idx,
                                  bali->free_high_idx, bali, &bit_word);
        if (bit_pos == -1) {
                bit_pos = find_free_range(bali->free_low_idx,
                                          bali->free_curr_idx,
                                          bali, &bit_word);
                if (bit_pos == -1) {
                        pr_debug("%s: Could not find an allocation unit on LUN:"
                                 " lun_id=%016llx\n", __func__, ba_lun->lun_id);
                        return -1ULL;
                }
        }

        /* Update the free_curr_idx */
        if (bit_pos == HIBIT)
                bali->free_curr_idx = bit_word + 1;
        else
                bali->free_curr_idx = bit_word;

        pr_debug("%s: Allocating AU number=%llx lun_id=%016llx "
                 "free_aun_cnt=%llx\n", __func__,
                 ((bit_word * BITS_PER_LONG) + bit_pos), ba_lun->lun_id,
                 bali->free_aun_cnt);

        return (u64) ((bit_word * BITS_PER_LONG) + bit_pos);
}

/**
 * validate_alloc() - validates the specified block has been allocated
 * @ba_lun_info:        LUN info owning the block allocator.
 * @aun:                Block to validate.
 *
 * Return: 0 on success, -1 on failure
 */
static int validate_alloc(struct ba_lun_info *bali, u64 aun)
{
        int idx = 0, bit_pos = 0;

        idx = aun / BITS_PER_LONG;
        bit_pos = aun % BITS_PER_LONG;

        if (test_bit(bit_pos, (ulong *)&bali->lun_alloc_map[idx]))
                return -1;

        return 0;
}

/**
 * ba_free() - frees a block from the block allocator
 * @ba_lun:     Block allocator from which to allocate a block.
 * @to_free:    Block to free.
 *
 * Return: 0 on success, -1 on failure
 */
static int ba_free(struct ba_lun *ba_lun, u64 to_free)
{
        int idx = 0, bit_pos = 0;
        struct ba_lun_info *bali = NULL;

        bali = ba_lun->ba_lun_handle;

        if (validate_alloc(bali, to_free)) {
                pr_debug("%s: AUN %llx is not allocated on lun_id=%016llx\n",
                         __func__, to_free, ba_lun->lun_id);
                return -1;
        }

        pr_debug("%s: Received a request to free AU=%llx lun_id=%016llx "
                 "free_aun_cnt=%llx\n", __func__, to_free, ba_lun->lun_id,
                 bali->free_aun_cnt);

        if (bali->aun_clone_map[to_free] > 0) {
                pr_debug("%s: AUN %llx lun_id=%016llx cloned. Clone count=%x\n",
                         __func__, to_free, ba_lun->lun_id,
                         bali->aun_clone_map[to_free]);
                bali->aun_clone_map[to_free]--;
                return 0;
        }

        idx = to_free / BITS_PER_LONG;
        bit_pos = to_free % BITS_PER_LONG;

        set_bit(bit_pos, (ulong *)&bali->lun_alloc_map[idx]);
        bali->free_aun_cnt++;

        if (idx < bali->free_low_idx)
                bali->free_low_idx = idx;
        else if (idx > bali->free_high_idx)
                bali->free_high_idx = idx;

        pr_debug("%s: Successfully freed AU bit_pos=%x bit map index=%x "
                 "lun_id=%016llx free_aun_cnt=%llx\n", __func__, bit_pos, idx,
                 ba_lun->lun_id, bali->free_aun_cnt);

        return 0;
}

/**
 * ba_clone() - Clone a chunk of the block allocation table
 * @ba_lun:     Block allocator from which to allocate a block.
 * @to_free:    Block to free.
 *
 * Return: 0 on success, -1 on failure
 */
static int ba_clone(struct ba_lun *ba_lun, u64 to_clone)
{
        struct ba_lun_info *bali = ba_lun->ba_lun_handle;

        if (validate_alloc(bali, to_clone)) {
                pr_debug("%s: AUN=%llx not allocated on lun_id=%016llx\n",
                         __func__, to_clone, ba_lun->lun_id);
                return -1;
        }

        pr_debug("%s: Received a request to clone AUN %llx on lun_id=%016llx\n",
                 __func__, to_clone, ba_lun->lun_id);

        if (bali->aun_clone_map[to_clone] == MAX_AUN_CLONE_CNT) {
                pr_debug("%s: AUN %llx on lun_id=%016llx hit max clones already\n",
                         __func__, to_clone, ba_lun->lun_id);
                return -1;
        }

        bali->aun_clone_map[to_clone]++;

        return 0;
}

/**
 * ba_space() - returns the amount of free space left in the block allocator
 * @ba_lun:     Block allocator.
 *
 * Return: Amount of free space in block allocator
 */
static u64 ba_space(struct ba_lun *ba_lun)
{
        struct ba_lun_info *bali = ba_lun->ba_lun_handle;

        return bali->free_aun_cnt;
}

/**
 * cxlflash_ba_terminate() - frees resources associated with the block allocator
 * @ba_lun:     Block allocator.
 *
 * Safe to call in a partially allocated state.
 */
void cxlflash_ba_terminate(struct ba_lun *ba_lun)
{
        struct ba_lun_info *bali = ba_lun->ba_lun_handle;

        if (bali) {
                kfree(bali->aun_clone_map);
                kfree(bali->lun_alloc_map);
                kfree(bali);
                ba_lun->ba_lun_handle = NULL;
        }
}

/**
 * init_vlun() - initializes a LUN for virtual use
 * @lun_info:   LUN information structure that owns the block allocator.
 *
 * Return: 0 on success, -errno on failure
 */
static int init_vlun(struct llun_info *lli)
{
        int rc = 0;
        struct glun_info *gli = lli->parent;
        struct blka *blka = &gli->blka;

        memset(blka, 0, sizeof(*blka));
        mutex_init(&blka->mutex);

        /* LUN IDs are unique per port, save the index instead */
        blka->ba_lun.lun_id = lli->lun_index;
        blka->ba_lun.lsize = gli->max_lba + 1;
        blka->ba_lun.lba_size = gli->blk_len;

        blka->ba_lun.au_size = MC_CHUNK_SIZE;
        blka->nchunk = blka->ba_lun.lsize / MC_CHUNK_SIZE;

        rc = ba_init(&blka->ba_lun);
        if (unlikely(rc))
                pr_debug("%s: cannot init block_alloc, rc=%d\n", __func__, rc);

        pr_debug("%s: returning rc=%d lli=%p\n", __func__, rc, lli);
        return rc;
}

/**
 * write_same16() - sends a SCSI WRITE_SAME16 (0) command to specified LUN
 * @sdev:       SCSI device associated with LUN.
 * @lba:        Logical block address to start write same.
 * @nblks:      Number of logical blocks to write same.
 *
 * The SCSI WRITE_SAME16 can take quite a while to complete. Should an EEH occur
 * while in scsi_execute(), the EEH handler will attempt to recover. As part of
 * the recovery, the handler drains all currently running ioctls, waiting until
 * they have completed before proceeding with a reset. As this routine is used
 * on the ioctl path, this can create a condition where the EEH handler becomes
 * stuck, infinitely waiting for this ioctl thread. To avoid this behavior,
 * temporarily unmark this thread as an ioctl thread by releasing the ioctl read
 * semaphore. This will allow the EEH handler to proceed with a recovery while
 * this thread is still running. Once the scsi_execute() returns, reacquire the
 * ioctl read semaphore and check the adapter state in case it changed while
 * inside of scsi_execute(). The state check will wait if the adapter is still
 * being recovered or return a failure if the recovery failed. In the event that
 * the adapter reset failed, simply return the failure as the ioctl would be
 * unable to continue.
 *
 * Note that the above puts a requirement on this routine to only be called on
 * an ioctl thread.
 *
 * Return: 0 on success, -errno on failure
 */
static int write_same16(struct scsi_device *sdev,
                        u64 lba,
                        u32 nblks)
{
        u8 *cmd_buf = NULL;
        u8 *scsi_cmd = NULL;
        int rc = 0;
        int result = 0;
        u64 offset = lba;
        int left = nblks;
        struct cxlflash_cfg *cfg = shost_priv(sdev->host);
        struct device *dev = &cfg->dev->dev;
        const u32 s = ilog2(sdev->sector_size) - 9;
        const u32 to = sdev->request_queue->rq_timeout;
        const u32 ws_limit = blk_queue_get_max_sectors(sdev->request_queue,
                                                       REQ_OP_WRITE_SAME) >> s;

        cmd_buf = kzalloc(CMD_BUFSIZE, GFP_KERNEL);
        scsi_cmd = kzalloc(MAX_COMMAND_SIZE, GFP_KERNEL);
        if (unlikely(!cmd_buf || !scsi_cmd)) {
                rc = -ENOMEM;
                goto out;
        }

        while (left > 0) {

                scsi_cmd[0] = WRITE_SAME_16;
                scsi_cmd[1] = cfg->ws_unmap ? 0x8 : 0;
                put_unaligned_be64(offset, &scsi_cmd[2]);
                put_unaligned_be32(ws_limit < left ? ws_limit : left,
                                   &scsi_cmd[10]);

                /* Drop the ioctl read semahpore across lengthy call */
                up_read(&cfg->ioctl_rwsem);
                result = scsi_execute(sdev, scsi_cmd, DMA_TO_DEVICE, cmd_buf,
                                      CMD_BUFSIZE, NULL, NULL, to,
                                      CMD_RETRIES, 0, 0, NULL);
                down_read(&cfg->ioctl_rwsem);
                rc = check_state(cfg);
                if (rc) {
                        dev_err(dev, "%s: Failed state result=%08x\n",
                                __func__, result);
                        rc = -ENODEV;
                        goto out;
                }

                if (result) {
                        dev_err_ratelimited(dev, "%s: command failed for "
                                            "offset=%lld result=%08x\n",
                                            __func__, offset, result);
                        rc = -EIO;
                        goto out;
                }
                left -= ws_limit;
                offset += ws_limit;
        }

out:
        kfree(cmd_buf);
        kfree(scsi_cmd);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
}

/**
 * grow_lxt() - expands the translation table associated with the specified RHTE
 * @afu:        AFU associated with the host.
 * @sdev:       SCSI device associated with LUN.
 * @ctxid:      Context ID of context owning the RHTE.
 * @rhndl:      Resource handle associated with the RHTE.
 * @rhte:       Resource handle entry (RHTE).
 * @new_size:   Number of translation entries associated with RHTE.
 *
 * By design, this routine employs a 'best attempt' allocation and will
 * truncate the requested size down if there is not sufficient space in
 * the block allocator to satisfy the request but there does exist some
 * amount of space. The user is made aware of this by returning the size
 * allocated.
 *
 * Return: 0 on success, -errno on failure
 */
static int grow_lxt(struct afu *afu,
                    struct scsi_device *sdev,
                    ctx_hndl_t ctxid,
                    res_hndl_t rhndl,
                    struct sisl_rht_entry *rhte,
                    u64 *new_size)
{
        struct cxlflash_cfg *cfg = shost_priv(sdev->host);
        struct device *dev = &cfg->dev->dev;
        struct sisl_lxt_entry *lxt = NULL, *lxt_old = NULL;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        struct blka *blka = &gli->blka;
        u32 av_size;
        u32 ngrps, ngrps_old;
        u64 aun;                /* chunk# allocated by block allocator */
        u64 delta = *new_size - rhte->lxt_cnt;
        u64 my_new_size;
        int i, rc = 0;

        /*
         * Check what is available in the block allocator before re-allocating
         * LXT array. This is done up front under the mutex which must not be
         * released until after allocation is complete.
         */
        mutex_lock(&blka->mutex);
        av_size = ba_space(&blka->ba_lun);
        if (unlikely(av_size <= 0)) {
                dev_dbg(dev, "%s: ba_space error av_size=%d\n",
                        __func__, av_size);
                mutex_unlock(&blka->mutex);
                rc = -ENOSPC;
                goto out;
        }

        if (av_size < delta)
                delta = av_size;

        lxt_old = rhte->lxt_start;
        ngrps_old = LXT_NUM_GROUPS(rhte->lxt_cnt);
        ngrps = LXT_NUM_GROUPS(rhte->lxt_cnt + delta);

        if (ngrps != ngrps_old) {
                /* reallocate to fit new size */
                lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
                              GFP_KERNEL);
                if (unlikely(!lxt)) {
                        mutex_unlock(&blka->mutex);
                        rc = -ENOMEM;
                        goto out;
                }

                /* copy over all old entries */
                memcpy(lxt, lxt_old, (sizeof(*lxt) * rhte->lxt_cnt));
        } else
                lxt = lxt_old;

        /* nothing can fail from now on */
        my_new_size = rhte->lxt_cnt + delta;

        /* add new entries to the end */
        for (i = rhte->lxt_cnt; i < my_new_size; i++) {
                /*
                 * Due to the earlier check of available space, ba_alloc
                 * cannot fail here. If it did due to internal error,
                 * leave a rlba_base of -1u which will likely be a
                 * invalid LUN (too large).
                 */
                aun = ba_alloc(&blka->ba_lun);
                if ((aun == -1ULL) || (aun >= blka->nchunk))
                        dev_dbg(dev, "%s: ba_alloc error allocated chunk=%llu "
                                "max=%llu\n", __func__, aun, blka->nchunk - 1);

                /* select both ports, use r/w perms from RHT */
                lxt[i].rlba_base = ((aun << MC_CHUNK_SHIFT) |
                                    (lli->lun_index << LXT_LUNIDX_SHIFT) |
                                    (RHT_PERM_RW << LXT_PERM_SHIFT |
                                     lli->port_sel));
        }

        mutex_unlock(&blka->mutex);

        /*
         * The following sequence is prescribed in the SISlite spec
         * for syncing up with the AFU when adding LXT entries.
         */
        dma_wmb(); /* Make LXT updates are visible */

        rhte->lxt_start = lxt;
        dma_wmb(); /* Make RHT entry's LXT table update visible */

        rhte->lxt_cnt = my_new_size;
        dma_wmb(); /* Make RHT entry's LXT table size update visible */

        rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_LW_SYNC);
        if (unlikely(rc))
                rc = -EAGAIN;

        /* free old lxt if reallocated */
        if (lxt != lxt_old)
                kfree(lxt_old);
        *new_size = my_new_size;
out:
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
}

/**
 * shrink_lxt() - reduces translation table associated with the specified RHTE
 * @afu:        AFU associated with the host.
 * @sdev:       SCSI device associated with LUN.
 * @rhndl:      Resource handle associated with the RHTE.
 * @rhte:       Resource handle entry (RHTE).
 * @ctxi:       Context owning resources.
 * @new_size:   Number of translation entries associated with RHTE.
 *
 * Return: 0 on success, -errno on failure
 */
static int shrink_lxt(struct afu *afu,
                      struct scsi_device *sdev,
                      res_hndl_t rhndl,
                      struct sisl_rht_entry *rhte,
                      struct ctx_info *ctxi,
                      u64 *new_size)
{
        struct cxlflash_cfg *cfg = shost_priv(sdev->host);
        struct device *dev = &cfg->dev->dev;
        struct sisl_lxt_entry *lxt, *lxt_old;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        struct blka *blka = &gli->blka;
        ctx_hndl_t ctxid = DECODE_CTXID(ctxi->ctxid);
        bool needs_ws = ctxi->rht_needs_ws[rhndl];
        bool needs_sync = !ctxi->err_recovery_active;
        u32 ngrps, ngrps_old;
        u64 aun;                /* chunk# allocated by block allocator */
        u64 delta = rhte->lxt_cnt - *new_size;
        u64 my_new_size;
        int i, rc = 0;

        lxt_old = rhte->lxt_start;
        ngrps_old = LXT_NUM_GROUPS(rhte->lxt_cnt);
        ngrps = LXT_NUM_GROUPS(rhte->lxt_cnt - delta);

        if (ngrps != ngrps_old) {
                /* Reallocate to fit new size unless new size is 0 */
                if (ngrps) {
                        lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
                                      GFP_KERNEL);
                        if (unlikely(!lxt)) {
                                rc = -ENOMEM;
                                goto out;
                        }

                        /* Copy over old entries that will remain */
                        memcpy(lxt, lxt_old,
                               (sizeof(*lxt) * (rhte->lxt_cnt - delta)));
                } else
                        lxt = NULL;
        } else
                lxt = lxt_old;

        /* Nothing can fail from now on */
        my_new_size = rhte->lxt_cnt - delta;

        /*
         * The following sequence is prescribed in the SISlite spec
         * for syncing up with the AFU when removing LXT entries.
         */
        rhte->lxt_cnt = my_new_size;
        dma_wmb(); /* Make RHT entry's LXT table size update visible */

        rhte->lxt_start = lxt;
        dma_wmb(); /* Make RHT entry's LXT table update visible */

        if (needs_sync) {
                rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_HW_SYNC);
                if (unlikely(rc))
                        rc = -EAGAIN;
        }

        if (needs_ws) {
                /*
                 * Mark the context as unavailable, so that we can release
                 * the mutex safely.
                 */
                ctxi->unavail = true;
                mutex_unlock(&ctxi->mutex);
        }

        /* Free LBAs allocated to freed chunks */
        mutex_lock(&blka->mutex);
        for (i = delta - 1; i >= 0; i--) {
                aun = lxt_old[my_new_size + i].rlba_base >> MC_CHUNK_SHIFT;
                if (needs_ws)
                        write_same16(sdev, aun, MC_CHUNK_SIZE);
                ba_free(&blka->ba_lun, aun);
        }
        mutex_unlock(&blka->mutex);

        if (needs_ws) {
                /* Make the context visible again */
                mutex_lock(&ctxi->mutex);
                ctxi->unavail = false;
        }

        /* Free old lxt if reallocated */
        if (lxt != lxt_old)
                kfree(lxt_old);
        *new_size = my_new_size;
out:
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
}

/**
 * _cxlflash_vlun_resize() - changes the size of a virtual LUN
 * @sdev:       SCSI device associated with LUN owning virtual LUN.
 * @ctxi:       Context owning resources.
 * @resize:     Resize ioctl data structure.
 *
 * On successful return, the user is informed of the new size (in blocks)
 * of the virtual LUN in last LBA format. When the size of the virtual
 * LUN is zero, the last LBA is reflected as -1. See comment in the
 * prologue for _cxlflash_disk_release() regarding AFU syncs and contexts
 * on the error recovery list.
 *
 * Return: 0 on success, -errno on failure
 */
int _cxlflash_vlun_resize(struct scsi_device *sdev,
                          struct ctx_info *ctxi,
                          struct dk_cxlflash_resize *resize)
{
        struct cxlflash_cfg *cfg = shost_priv(sdev->host);
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        struct afu *afu = cfg->afu;
        bool put_ctx = false;

        res_hndl_t rhndl = resize->rsrc_handle;
        u64 new_size;
        u64 nsectors;
        u64 ctxid = DECODE_CTXID(resize->context_id),
            rctxid = resize->context_id;

        struct sisl_rht_entry *rhte;

        int rc = 0;

        /*
         * The requested size (req_size) is always assumed to be in 4k blocks,
         * so we have to convert it here from 4k to chunk size.
         */
        nsectors = (resize->req_size * CXLFLASH_BLOCK_SIZE) / gli->blk_len;
        new_size = DIV_ROUND_UP(nsectors, MC_CHUNK_SIZE);

        dev_dbg(dev, "%s: ctxid=%llu rhndl=%llu req_size=%llu new_size=%llu\n",
                __func__, ctxid, resize->rsrc_handle, resize->req_size,
                new_size);

        if (unlikely(gli->mode != MODE_VIRTUAL)) {
                dev_dbg(dev, "%s: LUN mode does not support resize mode=%d\n",
                        __func__, gli->mode);
                rc = -EINVAL;
                goto out;

        }

        if (!ctxi) {
                ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
                if (unlikely(!ctxi)) {
                        dev_dbg(dev, "%s: Bad context ctxid=%llu\n",
                                __func__, ctxid);
                        rc = -EINVAL;
                        goto out;
                }

                put_ctx = true;
        }

        rhte = get_rhte(ctxi, rhndl, lli);
        if (unlikely(!rhte)) {
                dev_dbg(dev, "%s: Bad resource handle rhndl=%u\n",
                        __func__, rhndl);
                rc = -EINVAL;
                goto out;
        }

        if (new_size > rhte->lxt_cnt)
                rc = grow_lxt(afu, sdev, ctxid, rhndl, rhte, &new_size);
        else if (new_size < rhte->lxt_cnt)
                rc = shrink_lxt(afu, sdev, rhndl, rhte, ctxi, &new_size);
        else {
                /*
                 * Rare case where there is already sufficient space, just
                 * need to perform a translation sync with the AFU. This
                 * scenario likely follows a previous sync failure during
                 * a resize operation. Accordingly, perform the heavyweight
                 * form of translation sync as it is unknown which type of
                 * resize failed previously.
                 */
                rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_HW_SYNC);
                if (unlikely(rc)) {
                        rc = -EAGAIN;
                        goto out;
                }
        }

        resize->hdr.return_flags = 0;
        resize->last_lba = (new_size * MC_CHUNK_SIZE * gli->blk_len);
        resize->last_lba /= CXLFLASH_BLOCK_SIZE;
        resize->last_lba--;

out:
        if (put_ctx)
                put_context(ctxi);
        dev_dbg(dev, "%s: resized to %llu returning rc=%d\n",
                __func__, resize->last_lba, rc);
        return rc;
}

int cxlflash_vlun_resize(struct scsi_device *sdev,
                         struct dk_cxlflash_resize *resize)
{
        return _cxlflash_vlun_resize(sdev, NULL, resize);
}

/**
 * cxlflash_restore_luntable() - Restore LUN table to prior state
 * @cfg:        Internal structure associated with the host.
 */
void cxlflash_restore_luntable(struct cxlflash_cfg *cfg)
{
        struct llun_info *lli, *temp;
        u32 lind;
        int k;
        struct device *dev = &cfg->dev->dev;
        __be64 __iomem *fc_port_luns;

        mutex_lock(&global.mutex);

        list_for_each_entry_safe(lli, temp, &cfg->lluns, list) {
                if (!lli->in_table)
                        continue;

                lind = lli->lun_index;
                dev_dbg(dev, "%s: Virtual LUNs on slot %d:\n", __func__, lind);

                for (k = 0; k < cfg->num_fc_ports; k++)
                        if (lli->port_sel & (1 << k)) {
                                fc_port_luns = get_fc_port_luns(cfg, k);
                                writeq_be(lli->lun_id[k], &fc_port_luns[lind]);
                                dev_dbg(dev, "\t%d=%llx\n", k, lli->lun_id[k]);
                        }
        }

        mutex_unlock(&global.mutex);
}

/**
 * get_num_ports() - compute number of ports from port selection mask
 * @psm:        Port selection mask.
 *
 * Return: Population count of port selection mask
 */
static inline u8 get_num_ports(u32 psm)
{
        static const u8 bits[16] = { 0, 1, 1, 2, 1, 2, 2, 3,
                                     1, 2, 2, 3, 2, 3, 3, 4 };

        return bits[psm & 0xf];
}

/**
 * init_luntable() - write an entry in the LUN table
 * @cfg:        Internal structure associated with the host.
 * @lli:        Per adapter LUN information structure.
 *
 * On successful return, a LUN table entry is created:
 *      - at the top for LUNs visible on multiple ports.
 *      - at the bottom for LUNs visible only on one port.
 *
 * Return: 0 on success, -errno on failure
 */
static int init_luntable(struct cxlflash_cfg *cfg, struct llun_info *lli)
{
        u32 chan;
        u32 lind;
        u32 nports;
        int rc = 0;
        int k;
        struct device *dev = &cfg->dev->dev;
        __be64 __iomem *fc_port_luns;

        mutex_lock(&global.mutex);

        if (lli->in_table)
                goto out;

        nports = get_num_ports(lli->port_sel);
        if (nports == 0 || nports > cfg->num_fc_ports) {
                WARN(1, "Unsupported port configuration nports=%u", nports);
                rc = -EIO;
                goto out;
        }

        if (nports > 1) {
                /*
                 * When LUN is visible from multiple ports, we will put
                 * it in the top half of the LUN table.
                 */
                for (k = 0; k < cfg->num_fc_ports; k++) {
                        if (!(lli->port_sel & (1 << k)))
                                continue;

                        if (cfg->promote_lun_index == cfg->last_lun_index[k]) {
                                rc = -ENOSPC;
                                goto out;
                        }
                }

                lind = lli->lun_index = cfg->promote_lun_index;
                dev_dbg(dev, "%s: Virtual LUNs on slot %d:\n", __func__, lind);

                for (k = 0; k < cfg->num_fc_ports; k++) {
                        if (!(lli->port_sel & (1 << k)))
                                continue;

                        fc_port_luns = get_fc_port_luns(cfg, k);
                        writeq_be(lli->lun_id[k], &fc_port_luns[lind]);
                        dev_dbg(dev, "\t%d=%llx\n", k, lli->lun_id[k]);
                }

                cfg->promote_lun_index++;
        } else {
                /*
                 * When LUN is visible only from one port, we will put
                 * it in the bottom half of the LUN table.
                 */
                chan = PORTMASK2CHAN(lli->port_sel);
                if (cfg->promote_lun_index == cfg->last_lun_index[chan]) {
                        rc = -ENOSPC;
                        goto out;
                }

                lind = lli->lun_index = cfg->last_lun_index[chan];
                fc_port_luns = get_fc_port_luns(cfg, chan);
                writeq_be(lli->lun_id[chan], &fc_port_luns[lind]);
                cfg->last_lun_index[chan]--;
                dev_dbg(dev, "%s: Virtual LUNs on slot %d:\n\t%d=%llx\n",
                        __func__, lind, chan, lli->lun_id[chan]);
        }

        lli->in_table = true;
out:
        mutex_unlock(&global.mutex);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
}

/**
 * cxlflash_disk_virtual_open() - open a virtual disk of specified size
 * @sdev:       SCSI device associated with LUN owning virtual LUN.
 * @arg:        UVirtual ioctl data structure.
 *
 * On successful return, the user is informed of the resource handle
 * to be used to identify the virtual LUN and the size (in blocks) of
 * the virtual LUN in last LBA format. When the size of the virtual LUN
 * is zero, the last LBA is reflected as -1.
 *
 * Return: 0 on success, -errno on failure
 */
int cxlflash_disk_virtual_open(struct scsi_device *sdev, void *arg)
{
        struct cxlflash_cfg *cfg = shost_priv(sdev->host);
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;

        struct dk_cxlflash_uvirtual *virt = (struct dk_cxlflash_uvirtual *)arg;
        struct dk_cxlflash_resize resize;

        u64 ctxid = DECODE_CTXID(virt->context_id),
            rctxid = virt->context_id;
        u64 lun_size = virt->lun_size;
        u64 last_lba = 0;
        u64 rsrc_handle = -1;

        int rc = 0;

        struct ctx_info *ctxi = NULL;
        struct sisl_rht_entry *rhte = NULL;

        dev_dbg(dev, "%s: ctxid=%llu ls=%llu\n", __func__, ctxid, lun_size);

        /* Setup the LUNs block allocator on first call */
        mutex_lock(&gli->mutex);
        if (gli->mode == MODE_NONE) {
                rc = init_vlun(lli);
                if (rc) {
                        dev_err(dev, "%s: init_vlun failed rc=%d\n",
                                __func__, rc);
                        rc = -ENOMEM;
                        goto err0;
                }
        }

        rc = cxlflash_lun_attach(gli, MODE_VIRTUAL, true);
        if (unlikely(rc)) {
                dev_err(dev, "%s: Failed attach to LUN (VIRTUAL)\n", __func__);
                goto err0;
        }
        mutex_unlock(&gli->mutex);

        rc = init_luntable(cfg, lli);
        if (rc) {
                dev_err(dev, "%s: init_luntable failed rc=%d\n", __func__, rc);
                goto err1;
        }

        ctxi = get_context(cfg, rctxid, lli, 0);
        if (unlikely(!ctxi)) {
                dev_err(dev, "%s: Bad context ctxid=%llu\n", __func__, ctxid);
                rc = -EINVAL;
                goto err1;
        }

        rhte = rhte_checkout(ctxi, lli);
        if (unlikely(!rhte)) {
                dev_err(dev, "%s: too many opens ctxid=%llu\n",
                        __func__, ctxid);
                rc = -EMFILE;   /* too many opens  */
                goto err1;
        }

        rsrc_handle = (rhte - ctxi->rht_start);

        /* Populate RHT format 0 */
        rhte->nmask = MC_RHT_NMASK;
        rhte->fp = SISL_RHT_FP(0U, ctxi->rht_perms);

        /* Resize even if requested size is 0 */
        marshal_virt_to_resize(virt, &resize);
        resize.rsrc_handle = rsrc_handle;
        rc = _cxlflash_vlun_resize(sdev, ctxi, &resize);
        if (rc) {
                dev_err(dev, "%s: resize failed rc=%d\n", __func__, rc);
                goto err2;
        }
        last_lba = resize.last_lba;

        if (virt->hdr.flags & DK_CXLFLASH_UVIRTUAL_NEED_WRITE_SAME)
                ctxi->rht_needs_ws[rsrc_handle] = true;

        virt->hdr.return_flags = 0;
        virt->last_lba = last_lba;
        virt->rsrc_handle = rsrc_handle;

        if (get_num_ports(lli->port_sel) > 1)
                virt->hdr.return_flags |= DK_CXLFLASH_ALL_PORTS_ACTIVE;
out:
        if (likely(ctxi))
                put_context(ctxi);
        dev_dbg(dev, "%s: returning handle=%llu rc=%d llba=%llu\n",
                __func__, rsrc_handle, rc, last_lba);
        return rc;

err2:
        rhte_checkin(ctxi, rhte);
err1:
        cxlflash_lun_detach(gli);
        goto out;
err0:
        /* Special common cleanup prior to successful LUN attach */
        cxlflash_ba_terminate(&gli->blka.ba_lun);
        mutex_unlock(&gli->mutex);
        goto out;
}

/**
 * clone_lxt() - copies translation tables from source to destination RHTE
 * @afu:        AFU associated with the host.
 * @blka:       Block allocator associated with LUN.
 * @ctxid:      Context ID of context owning the RHTE.
 * @rhndl:      Resource handle associated with the RHTE.
 * @rhte:       Destination resource handle entry (RHTE).
 * @rhte_src:   Source resource handle entry (RHTE).
 *
 * Return: 0 on success, -errno on failure
 */
static int clone_lxt(struct afu *afu,
                     struct blka *blka,
                     ctx_hndl_t ctxid,
                     res_hndl_t rhndl,
                     struct sisl_rht_entry *rhte,
                     struct sisl_rht_entry *rhte_src)
{
        struct cxlflash_cfg *cfg = afu->parent;
        struct device *dev = &cfg->dev->dev;
        struct sisl_lxt_entry *lxt = NULL;
        bool locked = false;
        u32 ngrps;
        u64 aun;                /* chunk# allocated by block allocator */
        int j;
        int i = 0;
        int rc = 0;

        ngrps = LXT_NUM_GROUPS(rhte_src->lxt_cnt);

        if (ngrps) {
                /* allocate new LXTs for clone */
                lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
                                GFP_KERNEL);
                if (unlikely(!lxt)) {
                        rc = -ENOMEM;
                        goto out;
                }

                /* copy over */
                memcpy(lxt, rhte_src->lxt_start,
                       (sizeof(*lxt) * rhte_src->lxt_cnt));

                /* clone the LBAs in block allocator via ref_cnt, note that the
                 * block allocator mutex must be held until it is established
                 * that this routine will complete without the need for a
                 * cleanup.
                 */
                mutex_lock(&blka->mutex);
                locked = true;
                for (i = 0; i < rhte_src->lxt_cnt; i++) {
                        aun = (lxt[i].rlba_base >> MC_CHUNK_SHIFT);
                        if (ba_clone(&blka->ba_lun, aun) == -1ULL) {
                                rc = -EIO;
                                goto err;
                        }
                }
        }

        /*
         * The following sequence is prescribed in the SISlite spec
         * for syncing up with the AFU when adding LXT entries.
         */
        dma_wmb(); /* Make LXT updates are visible */

        rhte->lxt_start = lxt;
        dma_wmb(); /* Make RHT entry's LXT table update visible */

        rhte->lxt_cnt = rhte_src->lxt_cnt;
        dma_wmb(); /* Make RHT entry's LXT table size update visible */

        rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_LW_SYNC);
        if (unlikely(rc)) {
                rc = -EAGAIN;
                goto err2;
        }

out:
        if (locked)
                mutex_unlock(&blka->mutex);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
err2:
        /* Reset the RHTE */
        rhte->lxt_cnt = 0;
        dma_wmb();
        rhte->lxt_start = NULL;
        dma_wmb();
err:
        /* free the clones already made */
        for (j = 0; j < i; j++) {
                aun = (lxt[j].rlba_base >> MC_CHUNK_SHIFT);
                ba_free(&blka->ba_lun, aun);
        }
        kfree(lxt);
        goto out;
}

/**
 * cxlflash_disk_clone() - clone a context by making snapshot of another
 * @sdev:       SCSI device associated with LUN owning virtual LUN.
 * @clone:      Clone ioctl data structure.
 *
 * This routine effectively performs cxlflash_disk_open operation for each
 * in-use virtual resource in the source context. Note that the destination
 * context must be in pristine state and cannot have any resource handles
 * open at the time of the clone.
 *
 * Return: 0 on success, -errno on failure
 */
int cxlflash_disk_clone(struct scsi_device *sdev,
                        struct dk_cxlflash_clone *clone)
{
        struct cxlflash_cfg *cfg = shost_priv(sdev->host);
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        struct blka *blka = &gli->blka;
        struct afu *afu = cfg->afu;
        struct dk_cxlflash_release release = { { 0 }, 0 };

        struct ctx_info *ctxi_src = NULL,
                        *ctxi_dst = NULL;
        struct lun_access *lun_access_src, *lun_access_dst;
        u32 perms;
        u64 ctxid_src = DECODE_CTXID(clone->context_id_src),
            ctxid_dst = DECODE_CTXID(clone->context_id_dst),
            rctxid_src = clone->context_id_src,
            rctxid_dst = clone->context_id_dst;
        int i, j;
        int rc = 0;
        bool found;
        LIST_HEAD(sidecar);

        dev_dbg(dev, "%s: ctxid_src=%llu ctxid_dst=%llu\n",
                __func__, ctxid_src, ctxid_dst);

        /* Do not clone yourself */
        if (unlikely(rctxid_src == rctxid_dst)) {
                rc = -EINVAL;
                goto out;
        }

        if (unlikely(gli->mode != MODE_VIRTUAL)) {
                rc = -EINVAL;
                dev_dbg(dev, "%s: Only supported on virtual LUNs mode=%u\n",
                        __func__, gli->mode);
                goto out;
        }

        ctxi_src = get_context(cfg, rctxid_src, lli, CTX_CTRL_CLONE);
        ctxi_dst = get_context(cfg, rctxid_dst, lli, 0);
        if (unlikely(!ctxi_src || !ctxi_dst)) {
                dev_dbg(dev, "%s: Bad context ctxid_src=%llu ctxid_dst=%llu\n",
                        __func__, ctxid_src, ctxid_dst);
                rc = -EINVAL;
                goto out;
        }

        /* Verify there is no open resource handle in the destination context */
        for (i = 0; i < MAX_RHT_PER_CONTEXT; i++)
                if (ctxi_dst->rht_start[i].nmask != 0) {
                        rc = -EINVAL;
                        goto out;
                }

        /* Clone LUN access list */
        list_for_each_entry(lun_access_src, &ctxi_src->luns, list) {
                found = false;
                list_for_each_entry(lun_access_dst, &ctxi_dst->luns, list)
                        if (lun_access_dst->sdev == lun_access_src->sdev) {
                                found = true;
                                break;
                        }

                if (!found) {
                        lun_access_dst = kzalloc(sizeof(*lun_access_dst),
                                                 GFP_KERNEL);
                        if (unlikely(!lun_access_dst)) {
                                dev_err(dev, "%s: lun_access allocation fail\n",
                                        __func__);
                                rc = -ENOMEM;
                                goto out;
                        }

                        *lun_access_dst = *lun_access_src;
                        list_add(&lun_access_dst->list, &sidecar);
                }
        }

        if (unlikely(!ctxi_src->rht_out)) {
                dev_dbg(dev, "%s: Nothing to clone\n", __func__);
                goto out_success;
        }

        /* User specified permission on attach */
        perms = ctxi_dst->rht_perms;

        /*
         * Copy over checked-out RHT (and their associated LXT) entries by
         * hand, stopping after we've copied all outstanding entries and
         * cleaning up if the clone fails.
         *
         * Note: This loop is equivalent to performing cxlflash_disk_open and
         * cxlflash_vlun_resize. As such, LUN accounting needs to be taken into
         * account by attaching after each successful RHT entry clone. In the
         * event that a clone failure is experienced, the LUN detach is handled
         * via the cleanup performed by _cxlflash_disk_release.
         */
        for (i = 0; i < MAX_RHT_PER_CONTEXT; i++) {
                if (ctxi_src->rht_out == ctxi_dst->rht_out)
                        break;
                if (ctxi_src->rht_start[i].nmask == 0)
                        continue;

                /* Consume a destination RHT entry */
                ctxi_dst->rht_out++;
                ctxi_dst->rht_start[i].nmask = ctxi_src->rht_start[i].nmask;
                ctxi_dst->rht_start[i].fp =
                    SISL_RHT_FP_CLONE(ctxi_src->rht_start[i].fp, perms);
                ctxi_dst->rht_lun[i] = ctxi_src->rht_lun[i];

                rc = clone_lxt(afu, blka, ctxid_dst, i,
                               &ctxi_dst->rht_start[i],
                               &ctxi_src->rht_start[i]);
                if (rc) {
                        marshal_clone_to_rele(clone, &release);
                        for (j = 0; j < i; j++) {
                                release.rsrc_handle = j;
                                _cxlflash_disk_release(sdev, ctxi_dst,
                                                       &release);
                        }

                        /* Put back the one we failed on */
                        rhte_checkin(ctxi_dst, &ctxi_dst->rht_start[i]);
                        goto err;
                }

                cxlflash_lun_attach(gli, gli->mode, false);
        }

out_success:
        list_splice(&sidecar, &ctxi_dst->luns);

        /* fall through */
out:
        if (ctxi_src)
                put_context(ctxi_src);
        if (ctxi_dst)
                put_context(ctxi_dst);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;

err:
        list_for_each_entry_safe(lun_access_src, lun_access_dst, &sidecar, list)
                kfree(lun_access_src);
        goto out;
}