// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2014-2016 Christoph Hellwig.
 */
#include <linux/exportfs_block.h>
#include <linux/iomap.h>
#include <linux/slab.h>
#include <linux/pr.h>

#include <linux/nfsd/debug.h>

#include "blocklayoutxdr.h"
#include "pnfs.h"
#include "filecache.h"
#include "vfs.h"
#include "trace.h"

#define NFSDDBG_FACILITY        NFSDDBG_PNFS


/*
 * Get an extent from the file system that starts at offset or below
 * and may be shorter than the requested length.
 */
static __be32
nfsd4_block_map_extent(struct inode *inode, const struct svc_fh *fhp,
                u64 offset, u64 length, u32 iomode, u64 minlength,
                struct pnfs_block_extent *bex)
{
        struct super_block *sb = inode->i_sb;
        struct iomap iomap;
        u32 device_generation = 0;
        int error;

        error = sb->s_export_op->block_ops->map_blocks(inode, offset, length,
                        &iomap, iomode != IOMODE_READ, &device_generation);
        if (error) {
                if (error == -ENXIO)
                        return nfserr_layoutunavailable;
                return nfserrno(error);
        }

        switch (iomap.type) {
        case IOMAP_MAPPED:
                if (iomode == IOMODE_READ)
                        bex->es = PNFS_BLOCK_READ_DATA;
                else
                        bex->es = PNFS_BLOCK_READWRITE_DATA;
                bex->soff = iomap.addr;
                break;
        case IOMAP_UNWRITTEN:
                if (iomode & IOMODE_RW) {
                        /*
                         * Crack monkey special case from section 2.3.1.
                         */
                        if (minlength == 0) {
                                dprintk("pnfsd: no soup for you!\n");
                                return nfserr_layoutunavailable;
                        }

                        bex->es = PNFS_BLOCK_INVALID_DATA;
                        bex->soff = iomap.addr;
                        break;
                }
                fallthrough;
        case IOMAP_HOLE:
                if (iomode == IOMODE_READ) {
                        bex->es = PNFS_BLOCK_NONE_DATA;
                        break;
                }
                fallthrough;
        case IOMAP_DELALLOC:
        default:
                WARN(1, "pnfsd: filesystem returned %d extent\n", iomap.type);
                return nfserr_layoutunavailable;
        }

        error = nfsd4_set_deviceid(&bex->vol_id, fhp, device_generation);
        if (error)
                return nfserrno(error);

        bex->foff = iomap.offset;
        bex->len = iomap.length;
        return nfs_ok;
}

static __be32
nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode,
                const struct svc_fh *fhp, struct nfsd4_layoutget *args)
{
        struct nfsd4_layout_seg *seg = &args->lg_seg;
        struct pnfs_block_layout *bl;
        struct pnfs_block_extent *first_bex, *last_bex;
        u64 offset = seg->offset, length = seg->length;
        u32 i, nr_extents_max, block_size = i_blocksize(inode);
        __be32 nfserr;

        if (locks_in_grace(SVC_NET(rqstp)))
                return nfserr_grace;

        nfserr = nfserr_layoutunavailable;
        if (seg->offset & (block_size - 1)) {
                dprintk("pnfsd: I/O misaligned\n");
                goto out_error;
        }

        /*
         * RFC 8881, section 3.3.17:
         *   The layout4 data type defines a layout for a file.
         *
         * RFC 8881, section 18.43.3:
         *   The loga_maxcount field specifies the maximum layout size
         *   (in bytes) that the client can handle. If the size of the
         *   layout structure exceeds the size specified by maxcount,
         *   the metadata server will return the NFS4ERR_TOOSMALL error.
         */
        nfserr = nfserr_toosmall;
        if (args->lg_maxcount < PNFS_BLOCK_LAYOUT4_SIZE +
                                PNFS_BLOCK_EXTENT_SIZE)
                goto out_error;

        /*
         * Limit the maximum layout size to avoid allocating
         * a large buffer on the server for each layout request.
         */
        nr_extents_max = (min(args->lg_maxcount, PAGE_SIZE) -
                          PNFS_BLOCK_LAYOUT4_SIZE) / PNFS_BLOCK_EXTENT_SIZE;

        /*
         * Some clients barf on non-zero block numbers for NONE or INVALID
         * layouts, so make sure to zero the whole structure.
         */
        nfserr = nfserrno(-ENOMEM);
        bl = kzalloc_flex(*bl, extents, nr_extents_max);
        if (!bl)
                goto out_error;
        bl->nr_extents = nr_extents_max;
        args->lg_content = bl;

        for (i = 0; i < bl->nr_extents; i++) {
                struct pnfs_block_extent *bex = bl->extents + i;
                u64 bex_length;

                nfserr = nfsd4_block_map_extent(inode, fhp, offset, length,
                                seg->iomode, args->lg_minlength, bex);
                if (nfserr != nfs_ok)
                        goto out_error;

                bex_length = bex->len - (offset - bex->foff);
                if (bex_length >= length) {
                        bl->nr_extents = i + 1;
                        break;
                }

                offset = bex->foff + bex->len;
                length -= bex_length;
        }

        first_bex = bl->extents;
        last_bex = bl->extents + bl->nr_extents - 1;

        nfserr = nfserr_layoutunavailable;
        length = last_bex->foff + last_bex->len - seg->offset;
        if (length < args->lg_minlength) {
                dprintk("pnfsd: extent smaller than minlength\n");
                goto out_error;
        }

        seg->offset = first_bex->foff;
        seg->length = last_bex->foff - first_bex->foff + last_bex->len;
        return nfs_ok;

out_error:
        seg->length = 0;
        return nfserr;
}

static __be32
nfsd4_block_commit_blocks(struct inode *inode, struct nfsd4_layoutcommit *lcp,
                struct iomap *iomaps, int nr_iomaps)
{
        int error;

        /*
         * This ignores the client provided mtime in loca_time_modify, as a
         * fully client specified mtime doesn't really fit into the Linux
         * multi-grain timestamp architecture.
         *
         * RFC 8881 Section 18.42 makes it clear that the client provided
         * timestamp is a "may" condition, and clients that want to force a
         * specific timestamp should send a separate SETATTR in the compound.
         */
        error = inode->i_sb->s_export_op->block_ops->commit_blocks(inode,
                        iomaps, nr_iomaps,
                        lcp->lc_size_chg ? lcp->lc_newsize : 0);
        kfree(iomaps);
        return nfserrno(error);
}

#ifdef CONFIG_NFSD_BLOCKLAYOUT
static int
nfsd4_block_get_device_info_simple(struct super_block *sb,
                struct nfsd4_getdeviceinfo *gdp)
{
        struct pnfs_block_deviceaddr *dev;
        struct pnfs_block_volume *b;

        dev = kzalloc_flex(*dev, volumes, 1);
        if (!dev)
                return -ENOMEM;
        gdp->gd_device = dev;

        dev->nr_volumes = 1;
        b = &dev->volumes[0];

        b->type = PNFS_BLOCK_VOLUME_SIMPLE;
        b->simple.sig_len = PNFS_BLOCK_UUID_LEN;
        return sb->s_export_op->block_ops->get_uuid(sb, b->simple.sig,
                        &b->simple.sig_len, &b->simple.offset);
}

static __be32
nfsd4_block_proc_getdeviceinfo(struct super_block *sb,
                struct svc_rqst *rqstp,
                struct nfs4_client *clp,
                struct nfsd4_getdeviceinfo *gdp)
{
        if (bdev_is_partition(sb->s_bdev))
                return nfserr_inval;
        return nfserrno(nfsd4_block_get_device_info_simple(sb, gdp));
}

static __be32
nfsd4_block_proc_layoutcommit(struct inode *inode, struct svc_rqst *rqstp,
                struct nfsd4_layoutcommit *lcp)
{
        struct iomap *iomaps;
        int nr_iomaps;
        __be32 nfserr;

        rqstp->rq_arg = lcp->lc_up_layout;
        svcxdr_init_decode(rqstp);

        nfserr = nfsd4_block_decode_layoutupdate(&rqstp->rq_arg_stream,
                        &iomaps, &nr_iomaps, i_blocksize(inode));
        if (nfserr != nfs_ok)
                return nfserr;

        return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps);
}

const struct nfsd4_layout_ops bl_layout_ops = {
        /*
         * Pretend that we send notification to the client.  This is a blatant
         * lie to force recent Linux clients to cache our device IDs.
         * We rarely ever change the device ID, so the harm of leaking deviceids
         * for a while isn't too bad.  Unfortunately RFC5661 is a complete mess
         * in this regard, but I filed errata 4119 for this a while ago, and
         * hopefully the Linux client will eventually start caching deviceids
         * without this again.
         */
        .notify_types           =
                        NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
        .proc_getdeviceinfo     = nfsd4_block_proc_getdeviceinfo,
        .encode_getdeviceinfo   = nfsd4_block_encode_getdeviceinfo,
        .proc_layoutget         = nfsd4_block_proc_layoutget,
        .encode_layoutget       = nfsd4_block_encode_layoutget,
        .proc_layoutcommit      = nfsd4_block_proc_layoutcommit,
};
#endif /* CONFIG_NFSD_BLOCKLAYOUT */

#ifdef CONFIG_NFSD_SCSILAYOUT

#define NFSD_MDS_PR_FENCED      XA_MARK_0

/*
 * Clear the fence flag if the device already has an entry. This occurs
 * when a client re-registers after a previous fence, allowing new
 * layouts for this device.
 *
 * Insert only on first registration. This bounds cl_dev_fences to the
 * count of devices this client has accessed, preventing unbounded growth.
 */
static inline int nfsd4_scsi_fence_insert(struct nfs4_client *clp,
                                          dev_t device)
{
        struct xarray *xa = &clp->cl_dev_fences;
        int ret;

        xa_lock(xa);
        ret = __xa_insert(xa, device, XA_ZERO_ENTRY, GFP_KERNEL);
        if (ret == -EBUSY) {
                __xa_clear_mark(xa, device, NFSD_MDS_PR_FENCED);
                ret = 0;
        }
        xa_unlock(xa);
        clp->cl_fence_retry_warn = false;
        return ret;
}

static inline bool nfsd4_scsi_fence_set(struct nfs4_client *clp, dev_t device)
{
        struct xarray *xa = &clp->cl_dev_fences;
        bool skip;

        xa_lock(xa);
        skip = xa_get_mark(xa, device, NFSD_MDS_PR_FENCED);
        if (!skip)
                __xa_set_mark(xa, device, NFSD_MDS_PR_FENCED);
        xa_unlock(xa);
        return skip;
}

static inline void nfsd4_scsi_fence_clear(struct nfs4_client *clp, dev_t device)
{
        xa_clear_mark(&clp->cl_dev_fences, device, NFSD_MDS_PR_FENCED);
}

#define NFSD_MDS_PR_KEY         0x0100000000000000ULL

/*
 * We use the client ID as a unique key for the reservations.
 * This allows us to easily fence a client when recalls fail.
 */
static u64 nfsd4_scsi_pr_key(struct nfs4_client *clp)
{
        return ((u64)clp->cl_clientid.cl_boot << 32) | clp->cl_clientid.cl_id;
}

static const u8 designator_types[] = {
        PS_DESIGNATOR_EUI64,
        PS_DESIGNATOR_NAA,
};

static int
nfsd4_block_get_unique_id(struct gendisk *disk, struct pnfs_block_volume *b)
{
        int ret, i;

        for (i = 0; i < ARRAY_SIZE(designator_types); i++) {
                u8 type = designator_types[i];

                ret = disk->fops->get_unique_id(disk, b->scsi.designator, type);
                if (ret > 0) {
                        b->scsi.code_set = PS_CODE_SET_BINARY;
                        b->scsi.designator_type = type;
                        b->scsi.designator_len = ret;
                        return 0;
                }
        }

        return -EINVAL;
}

static int
nfsd4_block_get_device_info_scsi(struct super_block *sb,
                struct nfs4_client *clp,
                struct nfsd4_getdeviceinfo *gdp)
{
        struct pnfs_block_deviceaddr *dev;
        struct pnfs_block_volume *b;
        const struct pr_ops *ops;
        int ret;

        dev = kzalloc_flex(*dev, volumes, 1);
        if (!dev)
                return -ENOMEM;
        gdp->gd_device = dev;

        dev->nr_volumes = 1;
        b = &dev->volumes[0];

        b->type = PNFS_BLOCK_VOLUME_SCSI;
        b->scsi.pr_key = nfsd4_scsi_pr_key(clp);

        ret = nfsd4_block_get_unique_id(sb->s_bdev->bd_disk, b);
        if (ret < 0)
                goto out_free_dev;

        ret = -EINVAL;
        ops = sb->s_bdev->bd_disk->fops->pr_ops;
        if (!ops) {
                pr_err("pNFS: device %s does not support PRs.\n",
                        sb->s_id);
                goto out_free_dev;
        }

        ret = nfsd4_scsi_fence_insert(clp, sb->s_bdev->bd_dev);
        if (ret < 0)
                goto out_free_dev;

        ret = ops->pr_register(sb->s_bdev, 0, NFSD_MDS_PR_KEY, true);
        if (ret) {
                pr_err("pNFS: failed to register key for device %s.\n",
                        sb->s_id);
                goto out_free_dev;
        }

        ret = ops->pr_reserve(sb->s_bdev, NFSD_MDS_PR_KEY,
                        PR_EXCLUSIVE_ACCESS_REG_ONLY, 0);
        if (ret) {
                pr_err("pNFS: failed to reserve device %s.\n",
                        sb->s_id);
                goto out_free_dev;
        }

        return 0;

out_free_dev:
        kfree(dev);
        gdp->gd_device = NULL;
        return ret;
}

static __be32
nfsd4_scsi_proc_getdeviceinfo(struct super_block *sb,
                struct svc_rqst *rqstp,
                struct nfs4_client *clp,
                struct nfsd4_getdeviceinfo *gdp)
{
        if (bdev_is_partition(sb->s_bdev))
                return nfserr_inval;
        return nfserrno(nfsd4_block_get_device_info_scsi(sb, clp, gdp));
}
static __be32
nfsd4_scsi_proc_layoutcommit(struct inode *inode, struct svc_rqst *rqstp,
                struct nfsd4_layoutcommit *lcp)
{
        struct iomap *iomaps;
        int nr_iomaps;
        __be32 nfserr;

        rqstp->rq_arg = lcp->lc_up_layout;
        svcxdr_init_decode(rqstp);

        nfserr = nfsd4_scsi_decode_layoutupdate(&rqstp->rq_arg_stream,
                        &iomaps, &nr_iomaps, i_blocksize(inode));
        if (nfserr != nfs_ok)
                return nfserr;

        return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps);
}

/*
 * Perform the fence operation to prevent the client from accessing the
 * block device. If a fence operation is already in progress, wait for
 * it to complete before checking the NFSD_MDS_PR_FENCED flag. Once the
 * operation is complete, check the flag. If NFSD_MDS_PR_FENCED is set,
 * update the layout stateid by setting the ls_fenced flag to indicate
 * that the client has been fenced.
 *
 * The cl_fence_mutex ensures that the fence operation has been fully
 * completed, rather than just in progress, when returning from this
 * function.
 *
 * Return true if client was fenced otherwise return false.
 */
static bool
nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls, struct nfsd_file *file)
{
        struct nfs4_client *clp = ls->ls_stid.sc_client;
        struct block_device *bdev = file->nf_file->f_path.mnt->mnt_sb->s_bdev;
        int status;
        bool ret;

        mutex_lock(&clp->cl_fence_mutex);
        if (nfsd4_scsi_fence_set(clp, bdev->bd_dev)) {
                mutex_unlock(&clp->cl_fence_mutex);
                return true;
        }

        status = bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KEY,
                        nfsd4_scsi_pr_key(clp),
                        PR_EXCLUSIVE_ACCESS_REG_ONLY, true);
        /*
         * Reset to allow retry only when the command could not have
         * reached the device. Negative status means a local error
         * (e.g., -ENOMEM) prevented the command from being sent.
         * PR_STS_PATH_FAILED, PR_STS_PATH_FAST_FAILED, and
         * PR_STS_RETRY_PATH_FAILURE indicate transport path failures
         * before device delivery.
         *
         * For all other errors, the command may have reached the device
         * and the preempt may have succeeded. Avoid resetting, since
         * retrying a successful preempt returns PR_STS_IOERR or
         * PR_STS_RESERVATION_CONFLICT, which would cause an infinite
         * retry loop.
         */
        switch (status) {
        case 0:
        case PR_STS_IOERR:
        case PR_STS_RESERVATION_CONFLICT:
                ret = true;
                break;
        default:
                /* retry-able and other errors */
                ret = false;
                nfsd4_scsi_fence_clear(clp, bdev->bd_dev);
                break;
        }
        mutex_unlock(&clp->cl_fence_mutex);

        trace_nfsd_pnfs_fence(clp, bdev->bd_disk->disk_name, status);
        return ret;
}

const struct nfsd4_layout_ops scsi_layout_ops = {
        /*
         * Pretend that we send notification to the client.  This is a blatant
         * lie to force recent Linux clients to cache our device IDs.
         * We rarely ever change the device ID, so the harm of leaking deviceids
         * for a while isn't too bad.  Unfortunately RFC5661 is a complete mess
         * in this regard, but I filed errata 4119 for this a while ago, and
         * hopefully the Linux client will eventually start caching deviceids
         * without this again.
         */
        .notify_types           =
                        NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
        .proc_getdeviceinfo     = nfsd4_scsi_proc_getdeviceinfo,
        .encode_getdeviceinfo   = nfsd4_block_encode_getdeviceinfo,
        .proc_layoutget         = nfsd4_block_proc_layoutget,
        .encode_layoutget       = nfsd4_block_encode_layoutget,
        .proc_layoutcommit      = nfsd4_scsi_proc_layoutcommit,
        .fence_client           = nfsd4_scsi_fence_client,
};
#endif /* CONFIG_NFSD_SCSILAYOUT */