// SPDX-License-Identifier: GPL-2.0-or-later
/* dir.c: AFS filesystem directory handling
 *
 * Copyright (C) 2002, 2018 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/ctype.h>
#include <linux/sched.h>
#include <linux/iversion.h>
#include <linux/iov_iter.h>
#include <linux/task_io_accounting_ops.h>
#include "internal.h"
#include "afs_fs.h"
#include "xdr_fs.h"

static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
                                 unsigned int flags);
static int afs_dir_open(struct inode *inode, struct file *file);
static int afs_readdir(struct file *file, struct dir_context *ctx);
static int afs_d_revalidate(struct inode *dir, const struct qstr *name,
                            struct dentry *dentry, unsigned int flags);
static int afs_d_delete(const struct dentry *dentry);
static void afs_d_iput(struct dentry *dentry, struct inode *inode);
static bool afs_lookup_one_filldir(struct dir_context *ctx, const char *name, int nlen,
                                  loff_t fpos, u64 ino, unsigned dtype);
static bool afs_lookup_filldir(struct dir_context *ctx, const char *name, int nlen,
                              loff_t fpos, u64 ino, unsigned dtype);
static int afs_create(struct mnt_idmap *idmap, struct inode *dir,
                      struct dentry *dentry, umode_t mode, bool excl);
static struct dentry *afs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
                                struct dentry *dentry, umode_t mode);
static int afs_rmdir(struct inode *dir, struct dentry *dentry);
static int afs_unlink(struct inode *dir, struct dentry *dentry);
static int afs_link(struct dentry *from, struct inode *dir,
                    struct dentry *dentry);
static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir,
                       struct dentry *dentry, const char *content);
static int afs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
                      struct dentry *old_dentry, struct inode *new_dir,
                      struct dentry *new_dentry, unsigned int flags);

const struct file_operations afs_dir_file_operations = {
        .open           = afs_dir_open,
        .release        = afs_release,
        .iterate_shared = afs_readdir,
        .lock           = afs_lock,
        .llseek         = generic_file_llseek,
};

const struct inode_operations afs_dir_inode_operations = {
        .create         = afs_create,
        .lookup         = afs_lookup,
        .link           = afs_link,
        .unlink         = afs_unlink,
        .symlink        = afs_symlink,
        .mkdir          = afs_mkdir,
        .rmdir          = afs_rmdir,
        .rename         = afs_rename,
        .permission     = afs_permission,
        .getattr        = afs_getattr,
        .setattr        = afs_setattr,
};

const struct address_space_operations afs_dir_aops = {
        .writepages     = afs_single_writepages,
};

const struct dentry_operations afs_fs_dentry_operations = {
        .d_revalidate   = afs_d_revalidate,
        .d_delete       = afs_d_delete,
        .d_release      = afs_d_release,
        .d_automount    = afs_d_automount,
        .d_iput         = afs_d_iput,
};

struct afs_lookup_one_cookie {
        struct dir_context      ctx;
        struct qstr             name;
        bool                    found;
        struct afs_fid          fid;
};

struct afs_lookup_cookie {
        struct dir_context      ctx;
        struct qstr             name;
        unsigned short          nr_fids;
        struct afs_fid          fids[50];
};

static void afs_dir_unuse_cookie(struct afs_vnode *dvnode, int ret)
{
        if (ret == 0) {
                struct afs_vnode_cache_aux aux;
                loff_t i_size = i_size_read(&dvnode->netfs.inode);

                afs_set_cache_aux(dvnode, &aux);
                fscache_unuse_cookie(afs_vnode_cache(dvnode), &aux, &i_size);
        } else {
                fscache_unuse_cookie(afs_vnode_cache(dvnode), NULL, NULL);
        }
}

/*
 * Iterate through a kmapped directory segment, dumping a summary of
 * the contents.
 */
static size_t afs_dir_dump_step(void *iter_base, size_t progress, size_t len,
                                void *priv, void *priv2)
{
        do {
                union afs_xdr_dir_block *block = iter_base;

                pr_warn("[%05zx] %32phN\n", progress, block);
                iter_base += AFS_DIR_BLOCK_SIZE;
                progress += AFS_DIR_BLOCK_SIZE;
                len -= AFS_DIR_BLOCK_SIZE;
        } while (len > 0);

        return len;
}

/*
 * Dump the contents of a directory.
 */
static void afs_dir_dump(struct afs_vnode *dvnode)
{
        struct iov_iter iter;
        unsigned long long i_size = i_size_read(&dvnode->netfs.inode);

        pr_warn("DIR %llx:%llx is=%llx\n",
                dvnode->fid.vid, dvnode->fid.vnode, i_size);

        iov_iter_folio_queue(&iter, ITER_SOURCE, dvnode->directory, 0, 0, i_size);
        iterate_folioq(&iter, iov_iter_count(&iter), NULL, NULL,
                       afs_dir_dump_step);
}

/*
 * check that a directory folio is valid
 */
static bool afs_dir_check_block(struct afs_vnode *dvnode, size_t progress,
                                union afs_xdr_dir_block *block)
{
        if (block->hdr.magic != AFS_DIR_MAGIC) {
                pr_warn("%s(%lx): [%zx] bad magic %04x\n",
                       __func__, dvnode->netfs.inode.i_ino,
                       progress, ntohs(block->hdr.magic));
                trace_afs_dir_check_failed(dvnode, progress);
                trace_afs_file_error(dvnode, -EIO, afs_file_error_dir_bad_magic);
                return false;
        }

        /* Make sure each block is NUL terminated so we can reasonably
         * use string functions on it.  The filenames in the folio
         * *should* be NUL-terminated anyway.
         */
        ((u8 *)block)[AFS_DIR_BLOCK_SIZE - 1] = 0;
        afs_stat_v(dvnode, n_read_dir);
        return true;
}

/*
 * Iterate through a kmapped directory segment, checking the content.
 */
static size_t afs_dir_check_step(void *iter_base, size_t progress, size_t len,
                                 void *priv, void *priv2)
{
        struct afs_vnode *dvnode = priv;

        if (WARN_ON_ONCE(progress % AFS_DIR_BLOCK_SIZE ||
                         len % AFS_DIR_BLOCK_SIZE))
                return len;

        do {
                if (!afs_dir_check_block(dvnode, progress, iter_base))
                        break;
                iter_base += AFS_DIR_BLOCK_SIZE;
                len -= AFS_DIR_BLOCK_SIZE;
        } while (len > 0);

        return len;
}

/*
 * Check all the blocks in a directory.
 */
static int afs_dir_check(struct afs_vnode *dvnode)
{
        struct iov_iter iter;
        unsigned long long i_size = i_size_read(&dvnode->netfs.inode);
        size_t checked = 0;

        if (unlikely(!i_size))
                return 0;

        iov_iter_folio_queue(&iter, ITER_SOURCE, dvnode->directory, 0, 0, i_size);
        checked = iterate_folioq(&iter, iov_iter_count(&iter), dvnode, NULL,
                                 afs_dir_check_step);
        if (checked != i_size) {
                afs_dir_dump(dvnode);
                return -EIO;
        }
        return 0;
}

/*
 * open an AFS directory file
 */
static int afs_dir_open(struct inode *inode, struct file *file)
{
        _enter("{%lu}", inode->i_ino);

        BUILD_BUG_ON(sizeof(union afs_xdr_dir_block) != 2048);
        BUILD_BUG_ON(sizeof(union afs_xdr_dirent) != 32);

        if (test_bit(AFS_VNODE_DELETED, &AFS_FS_I(inode)->flags))
                return -ENOENT;

        return afs_open(inode, file);
}

/*
 * Read a file in a single download.
 */
static ssize_t afs_do_read_single(struct afs_vnode *dvnode, struct file *file)
{
        struct iov_iter iter;
        ssize_t ret;
        loff_t i_size;
        bool is_dir = (S_ISDIR(dvnode->netfs.inode.i_mode) &&
                       !test_bit(AFS_VNODE_MOUNTPOINT, &dvnode->flags));

        i_size = i_size_read(&dvnode->netfs.inode);
        if (is_dir) {
                if (i_size < AFS_DIR_BLOCK_SIZE)
                        return afs_bad(dvnode, afs_file_error_dir_small);
                if (i_size > AFS_DIR_BLOCK_SIZE * 1024) {
                        trace_afs_file_error(dvnode, -EFBIG, afs_file_error_dir_big);
                        return -EFBIG;
                }
        } else {
                if (i_size > AFSPATHMAX) {
                        trace_afs_file_error(dvnode, -EFBIG, afs_file_error_dir_big);
                        return -EFBIG;
                }
        }

        /* Expand the storage.  TODO: Shrink the storage too. */
        if (dvnode->directory_size < i_size) {
                size_t cur_size = dvnode->directory_size;

                ret = netfs_alloc_folioq_buffer(NULL,
                                                &dvnode->directory, &cur_size, i_size,
                                                mapping_gfp_mask(dvnode->netfs.inode.i_mapping));
                dvnode->directory_size = cur_size;
                if (ret < 0)
                        return ret;
        }

        iov_iter_folio_queue(&iter, ITER_DEST, dvnode->directory, 0, 0, dvnode->directory_size);

        /* AFS requires us to perform the read of a directory synchronously as
         * a single unit to avoid issues with the directory contents being
         * changed between reads.
         */
        ret = netfs_read_single(&dvnode->netfs.inode, file, &iter);
        if (ret >= 0) {
                i_size = i_size_read(&dvnode->netfs.inode);
                if (i_size > ret) {
                        /* The content has grown, so we need to expand the
                         * buffer.
                         */
                        ret = -ESTALE;
                } else if (is_dir) {
                        int ret2 = afs_dir_check(dvnode);

                        if (ret2 < 0)
                                ret = ret2;
                } else if (i_size < folioq_folio_size(dvnode->directory, 0)) {
                        /* NUL-terminate a symlink. */
                        char *symlink = kmap_local_folio(folioq_folio(dvnode->directory, 0), 0);

                        symlink[i_size] = 0;
                        kunmap_local(symlink);
                }
        }

        return ret;
}

ssize_t afs_read_single(struct afs_vnode *dvnode, struct file *file)
{
        ssize_t ret;

        fscache_use_cookie(afs_vnode_cache(dvnode), false);
        ret = afs_do_read_single(dvnode, file);
        fscache_unuse_cookie(afs_vnode_cache(dvnode), NULL, NULL);
        return ret;
}

/*
 * Read the directory into a folio_queue buffer in one go, scrubbing the
 * previous contents.  We return -ESTALE if the caller needs to call us again.
 */
ssize_t afs_read_dir(struct afs_vnode *dvnode, struct file *file)
        __acquires(&dvnode->validate_lock)
{
        ssize_t ret;
        loff_t i_size;

        i_size = i_size_read(&dvnode->netfs.inode);

        ret = -ERESTARTSYS;
        if (down_read_killable(&dvnode->validate_lock) < 0)
                goto error;

        /* We only need to reread the data if it became invalid - or if we
         * haven't read it yet.
         */
        if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
            test_bit(AFS_VNODE_DIR_READ, &dvnode->flags)) {
                ret = i_size;
                goto valid;
        }

        up_read(&dvnode->validate_lock);
        if (down_write_killable(&dvnode->validate_lock) < 0)
                goto error;

        if (!test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
                afs_invalidate_cache(dvnode, 0);

        if (!test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) ||
            !test_bit(AFS_VNODE_DIR_READ, &dvnode->flags)) {
                trace_afs_reload_dir(dvnode);
                ret = afs_read_single(dvnode, file);
                if (ret < 0)
                        goto error_unlock;

                // TODO: Trim excess pages

                set_bit(AFS_VNODE_DIR_VALID, &dvnode->flags);
                set_bit(AFS_VNODE_DIR_READ, &dvnode->flags);
        } else {
                ret = i_size;
        }

        downgrade_write(&dvnode->validate_lock);
valid:
        return ret;

error_unlock:
        up_write(&dvnode->validate_lock);
error:
        _leave(" = %zd", ret);
        return ret;
}

/*
 * deal with one block in an AFS directory
 */
static int afs_dir_iterate_block(struct afs_vnode *dvnode,
                                 struct dir_context *ctx,
                                 union afs_xdr_dir_block *block)
{
        union afs_xdr_dirent *dire;
        unsigned int blknum, base, hdr, pos, next, nr_slots;
        size_t nlen;
        int tmp;

        blknum  = ctx->pos / AFS_DIR_BLOCK_SIZE;
        base    = blknum * AFS_DIR_SLOTS_PER_BLOCK;
        hdr     = (blknum == 0 ? AFS_DIR_RESV_BLOCKS0 : AFS_DIR_RESV_BLOCKS);
        pos     = DIV_ROUND_UP(ctx->pos, AFS_DIR_DIRENT_SIZE) - base;

        _enter("%llx,%x", ctx->pos, blknum);

        /* walk through the block, an entry at a time */
        for (unsigned int slot = hdr; slot < AFS_DIR_SLOTS_PER_BLOCK; slot = next) {
                /* skip entries marked unused in the bitmap */
                if (!(block->hdr.bitmap[slot / 8] &
                      (1 << (slot % 8)))) {
                        _debug("ENT[%x]: Unused", base + slot);
                        next = slot + 1;
                        if (next >= pos)
                                ctx->pos = (base + next) * sizeof(union afs_xdr_dirent);
                        continue;
                }

                /* got a valid entry */
                dire = &block->dirents[slot];
                nlen = strnlen(dire->u.name,
                               (unsigned long)(block + 1) - (unsigned long)dire->u.name - 1);
                if (nlen > AFSNAMEMAX - 1) {
                        _debug("ENT[%x]: Name too long (len %zx)",
                               base + slot, nlen);
                        return afs_bad(dvnode, afs_file_error_dir_name_too_long);
                }

                _debug("ENT[%x]: %s %zx \"%s\"",
                       base + slot, (slot < pos ? "skip" : "fill"),
                       nlen, dire->u.name);

                nr_slots = afs_dir_calc_slots(nlen);
                next = slot + nr_slots;
                if (next > AFS_DIR_SLOTS_PER_BLOCK) {
                        _debug("ENT[%x]: extends beyond end dir block (len %zx)",
                               base + slot, nlen);
                        return afs_bad(dvnode, afs_file_error_dir_over_end);
                }

                /* Check that the name-extension dirents are all allocated */
                for (tmp = 1; tmp < nr_slots; tmp++) {
                        unsigned int xslot = slot + tmp;

                        if (!(block->hdr.bitmap[xslot / 8] & (1 << (xslot % 8)))) {
                                _debug("ENT[%x]: Unmarked extension (%x/%x)",
                                       base + slot, tmp, nr_slots);
                                return afs_bad(dvnode, afs_file_error_dir_unmarked_ext);
                        }
                }

                /* skip if starts before the current position */
                if (slot < pos) {
                        if (next > pos)
                                ctx->pos = (base + next) * sizeof(union afs_xdr_dirent);
                        continue;
                }

                /* found the next entry */
                if (!dir_emit(ctx, dire->u.name, nlen,
                              ntohl(dire->u.vnode),
                              (ctx->actor == afs_lookup_filldir ||
                               ctx->actor == afs_lookup_one_filldir)?
                              ntohl(dire->u.unique) : DT_UNKNOWN)) {
                        _leave(" = 0 [full]");
                        return 0;
                }

                ctx->pos = (base + next) * sizeof(union afs_xdr_dirent);
        }

        _leave(" = 1 [more]");
        return 1;
}

struct afs_dir_iteration_ctx {
        struct dir_context      *dir_ctx;
        int                     error;
};

/*
 * Iterate through a kmapped directory segment.
 */
static size_t afs_dir_iterate_step(void *iter_base, size_t progress, size_t len,
                                   void *priv, void *priv2)
{
        struct afs_dir_iteration_ctx *ctx = priv2;
        struct afs_vnode *dvnode = priv;
        int ret;

        if (WARN_ON_ONCE(progress % AFS_DIR_BLOCK_SIZE ||
                         len % AFS_DIR_BLOCK_SIZE)) {
                pr_err("Mis-iteration prog=%zx len=%zx\n",
                       progress % AFS_DIR_BLOCK_SIZE,
                       len % AFS_DIR_BLOCK_SIZE);
                return len;
        }

        do {
                ret = afs_dir_iterate_block(dvnode, ctx->dir_ctx, iter_base);
                if (ret != 1)
                        break;

                ctx->dir_ctx->pos = round_up(ctx->dir_ctx->pos, AFS_DIR_BLOCK_SIZE);
                iter_base += AFS_DIR_BLOCK_SIZE;
                len -= AFS_DIR_BLOCK_SIZE;
        } while (len > 0);

        return len;
}

/*
 * Iterate through the directory folios.
 */
static int afs_dir_iterate_contents(struct inode *dir, struct dir_context *dir_ctx)
{
        struct afs_dir_iteration_ctx ctx = { .dir_ctx = dir_ctx };
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        struct iov_iter iter;
        unsigned long long i_size = i_size_read(dir);

        /* Round the file position up to the next entry boundary */
        dir_ctx->pos = round_up(dir_ctx->pos, sizeof(union afs_xdr_dirent));

        if (i_size <= 0 || dir_ctx->pos >= i_size)
                return 0;

        iov_iter_folio_queue(&iter, ITER_SOURCE, dvnode->directory, 0, 0, i_size);
        iov_iter_advance(&iter, round_down(dir_ctx->pos, AFS_DIR_BLOCK_SIZE));

        iterate_folioq(&iter, iov_iter_count(&iter), dvnode, &ctx,
                       afs_dir_iterate_step);

        if (ctx.error == -ESTALE)
                afs_invalidate_dir(dvnode, afs_dir_invalid_iter_stale);
        return ctx.error;
}

/*
 * iterate through the data blob that lists the contents of an AFS directory
 */
static int afs_dir_iterate(struct inode *dir, struct dir_context *ctx,
                           struct file *file, afs_dataversion_t *_dir_version)
{
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        int retry_limit = 100;
        int ret;

        _enter("{%lu},%llx,,", dir->i_ino, ctx->pos);

        do {
                if (--retry_limit < 0) {
                        pr_warn("afs_read_dir(): Too many retries\n");
                        ret = -ESTALE;
                        break;
                }
                ret = afs_read_dir(dvnode, file);
                if (ret < 0) {
                        if (ret != -ESTALE)
                                break;
                        if (test_bit(AFS_VNODE_DELETED, &AFS_FS_I(dir)->flags)) {
                                ret = -ESTALE;
                                break;
                        }
                        continue;
                }
                *_dir_version = inode_peek_iversion_raw(dir);

                ret = afs_dir_iterate_contents(dir, ctx);
                up_read(&dvnode->validate_lock);
        } while (ret == -ESTALE);

        _leave(" = %d", ret);
        return ret;
}

/*
 * read an AFS directory
 */
static int afs_readdir(struct file *file, struct dir_context *ctx)
{
        afs_dataversion_t dir_version;

        return afs_dir_iterate(file_inode(file), ctx, file, &dir_version);
}

/*
 * Search the directory for a single name
 * - if afs_dir_iterate_block() spots this function, it'll pass the FID
 *   uniquifier through dtype
 */
static bool afs_lookup_one_filldir(struct dir_context *ctx, const char *name,
                                  int nlen, loff_t fpos, u64 ino, unsigned dtype)
{
        struct afs_lookup_one_cookie *cookie =
                container_of(ctx, struct afs_lookup_one_cookie, ctx);

        _enter("{%s,%u},%s,%u,,%llu,%u",
               cookie->name.name, cookie->name.len, name, nlen,
               (unsigned long long) ino, dtype);

        /* insanity checks first */
        BUILD_BUG_ON(sizeof(union afs_xdr_dir_block) != 2048);
        BUILD_BUG_ON(sizeof(union afs_xdr_dirent) != 32);

        if (cookie->name.len != nlen ||
            memcmp(cookie->name.name, name, nlen) != 0) {
                _leave(" = true [keep looking]");
                return true;
        }

        cookie->fid.vnode = ino;
        cookie->fid.unique = dtype;
        cookie->found = 1;

        _leave(" = false [found]");
        return false;
}

/*
 * Do a lookup of a single name in a directory
 * - just returns the FID the dentry name maps to if found
 */
static int afs_do_lookup_one(struct inode *dir, const struct qstr *name,
                             struct afs_fid *fid,
                             afs_dataversion_t *_dir_version)
{
        struct afs_super_info *as = dir->i_sb->s_fs_info;
        struct afs_lookup_one_cookie cookie = {
                .ctx.actor = afs_lookup_one_filldir,
                .name = *name,
                .fid.vid = as->volume->vid
        };
        int ret;

        _enter("{%lu},{%.*s},", dir->i_ino, name->len, name->name);

        /* search the directory */
        ret = afs_dir_iterate(dir, &cookie.ctx, NULL, _dir_version);
        if (ret < 0) {
                _leave(" = %d [iter]", ret);
                return ret;
        }

        if (!cookie.found) {
                _leave(" = -ENOENT [not found]");
                return -ENOENT;
        }

        *fid = cookie.fid;
        _leave(" = 0 { vn=%llu u=%u }", fid->vnode, fid->unique);
        return 0;
}

/*
 * search the directory for a name
 * - if afs_dir_iterate_block() spots this function, it'll pass the FID
 *   uniquifier through dtype
 */
static bool afs_lookup_filldir(struct dir_context *ctx, const char *name,
                              int nlen, loff_t fpos, u64 ino, unsigned dtype)
{
        struct afs_lookup_cookie *cookie =
                container_of(ctx, struct afs_lookup_cookie, ctx);

        _enter("{%s,%u},%s,%u,,%llu,%u",
               cookie->name.name, cookie->name.len, name, nlen,
               (unsigned long long) ino, dtype);

        /* insanity checks first */
        BUILD_BUG_ON(sizeof(union afs_xdr_dir_block) != 2048);
        BUILD_BUG_ON(sizeof(union afs_xdr_dirent) != 32);

        if (cookie->nr_fids < 50) {
                cookie->fids[cookie->nr_fids].vnode     = ino;
                cookie->fids[cookie->nr_fids].unique    = dtype;
                cookie->nr_fids++;
        }

        return cookie->nr_fids < 50;
}

/*
 * Deal with the result of a successful lookup operation.  Turn all the files
 * into inodes and save the first one - which is the one we actually want.
 */
static void afs_do_lookup_success(struct afs_operation *op)
{
        struct afs_vnode_param *vp;
        struct afs_vnode *vnode;
        struct inode *inode;
        u32 abort_code;
        int i;

        _enter("");

        for (i = 0; i < op->nr_files; i++) {
                switch (i) {
                case 0:
                        vp = &op->file[0];
                        abort_code = vp->scb.status.abort_code;
                        if (abort_code != 0) {
                                op->call_abort_code = abort_code;
                                afs_op_set_error(op, afs_abort_to_error(abort_code));
                                op->cumul_error.abort_code = abort_code;
                        }
                        break;

                case 1:
                        vp = &op->file[1];
                        break;

                default:
                        vp = &op->more_files[i - 2];
                        break;
                }

                if (vp->scb.status.abort_code)
                        trace_afs_bulkstat_error(op, &vp->fid, i, vp->scb.status.abort_code);
                if (!vp->scb.have_status && !vp->scb.have_error)
                        continue;

                _debug("do [%u]", i);
                if (vp->vnode) {
                        if (!test_bit(AFS_VNODE_UNSET, &vp->vnode->flags))
                                afs_vnode_commit_status(op, vp);
                } else if (vp->scb.status.abort_code == 0) {
                        inode = afs_iget(op, vp);
                        if (!IS_ERR(inode)) {
                                vnode = AFS_FS_I(inode);
                                afs_cache_permit(vnode, op->key,
                                                 0 /* Assume vnode->cb_break is 0 */ +
                                                 op->cb_v_break,
                                                 &vp->scb);
                                vp->vnode = vnode;
                                vp->put_vnode = true;
                        }
                } else {
                        _debug("- abort %d %llx:%llx.%x",
                               vp->scb.status.abort_code,
                               vp->fid.vid, vp->fid.vnode, vp->fid.unique);
                }
        }

        _leave("");
}

static const struct afs_operation_ops afs_inline_bulk_status_operation = {
        .issue_afs_rpc  = afs_fs_inline_bulk_status,
        .issue_yfs_rpc  = yfs_fs_inline_bulk_status,
        .success        = afs_do_lookup_success,
};

static const struct afs_operation_ops afs_lookup_fetch_status_operation = {
        .issue_afs_rpc  = afs_fs_fetch_status,
        .issue_yfs_rpc  = yfs_fs_fetch_status,
        .success        = afs_do_lookup_success,
        .aborted        = afs_check_for_remote_deletion,
};

/*
 * See if we know that the server we expect to use doesn't support
 * FS.InlineBulkStatus.
 */
static bool afs_server_supports_ibulk(struct afs_vnode *dvnode)
{
        struct afs_server_list *slist;
        struct afs_volume *volume = dvnode->volume;
        struct afs_server *server;
        bool ret = true;
        int i;

        if (!test_bit(AFS_VOLUME_MAYBE_NO_IBULK, &volume->flags))
                return true;

        rcu_read_lock();
        slist = rcu_dereference(volume->servers);

        for (i = 0; i < slist->nr_servers; i++) {
                server = slist->servers[i].server;
                if (server == dvnode->cb_server) {
                        if (test_bit(AFS_SERVER_FL_NO_IBULK, &server->flags))
                                ret = false;
                        break;
                }
        }

        rcu_read_unlock();
        return ret;
}

/*
 * Do a lookup in a directory.  We make use of bulk lookup to query a slew of
 * files in one go and create inodes for them.  The inode of the file we were
 * asked for is returned.
 */
static struct inode *afs_do_lookup(struct inode *dir, struct dentry *dentry)
{
        struct afs_lookup_cookie *cookie;
        struct afs_vnode_param *vp;
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir), *vnode;
        struct inode *inode = NULL, *ti;
        afs_dataversion_t data_version = READ_ONCE(dvnode->status.data_version);
        bool supports_ibulk, isnew;
        long ret;
        int i;

        _enter("{%lu},%p{%pd},", dir->i_ino, dentry, dentry);

        cookie = kzalloc_obj(struct afs_lookup_cookie);
        if (!cookie)
                return ERR_PTR(-ENOMEM);

        for (i = 0; i < ARRAY_SIZE(cookie->fids); i++)
                cookie->fids[i].vid = dvnode->fid.vid;
        cookie->ctx.actor = afs_lookup_filldir;
        cookie->name = dentry->d_name;
        cookie->nr_fids = 2; /* slot 1 is saved for the fid we actually want
                              * and slot 0 for the directory */

        /* Search the directory for the named entry using the hash table... */
        ret = afs_dir_search(dvnode, &dentry->d_name, &cookie->fids[1], &data_version);
        if (ret < 0)
                goto out;

        supports_ibulk = afs_server_supports_ibulk(dvnode);
        if (supports_ibulk) {
                /* ...then scan linearly from that point for entries to lookup-ahead. */
                cookie->ctx.pos = (ret + 1) * AFS_DIR_DIRENT_SIZE;
                afs_dir_iterate(dir, &cookie->ctx, NULL, &data_version);
        }

        dentry->d_fsdata = (void *)(unsigned long)data_version;

        /* Check to see if we already have an inode for the primary fid. */
        inode = ilookup5(dir->i_sb, cookie->fids[1].vnode,
                         afs_ilookup5_test_by_fid, &cookie->fids[1]);
        if (inode)
                goto out; /* We do */

        /* Okay, we didn't find it.  We need to query the server - and whilst
         * we're doing that, we're going to attempt to look up a bunch of other
         * vnodes also.
         */
        op = afs_alloc_operation(NULL, dvnode->volume);
        if (IS_ERR(op)) {
                ret = PTR_ERR(op);
                goto out;
        }

        afs_op_set_vnode(op, 0, dvnode);
        afs_op_set_fid(op, 1, &cookie->fids[1]);

        op->nr_files = cookie->nr_fids;
        _debug("nr_files %u", op->nr_files);

        /* Need space for examining all the selected files */
        if (op->nr_files > 2) {
                op->more_files = kvzalloc_objs(struct afs_vnode_param,
                                               op->nr_files - 2);
                if (!op->more_files) {
                        afs_op_nomem(op);
                        goto out_op;
                }

                for (i = 2; i < op->nr_files; i++) {
                        vp = &op->more_files[i - 2];
                        vp->fid = cookie->fids[i];

                        /* Find any inodes that already exist and get their
                         * callback counters.
                         */
                        ti = ilookup5_nowait(dir->i_sb, vp->fid.vnode,
                                             afs_ilookup5_test_by_fid, &vp->fid, &isnew);
                        if (!IS_ERR_OR_NULL(ti)) {
                                vnode = AFS_FS_I(ti);
                                vp->dv_before = vnode->status.data_version;
                                vp->cb_break_before = afs_calc_vnode_cb_break(vnode);
                                vp->vnode = vnode;
                                vp->put_vnode = true;
                                vp->speculative = true; /* vnode not locked */
                        }
                }
        }

        /* Try FS.InlineBulkStatus first.  Abort codes for the individual
         * lookups contained therein are stored in the reply without aborting
         * the whole operation.
         */
        afs_op_set_error(op, -ENOTSUPP);
        if (supports_ibulk) {
                op->ops = &afs_inline_bulk_status_operation;
                afs_begin_vnode_operation(op);
                afs_wait_for_operation(op);
        }

        if (afs_op_error(op) == -ENOTSUPP) {
                /* We could try FS.BulkStatus next, but this aborts the entire
                 * op if any of the lookups fails - so, for the moment, revert
                 * to FS.FetchStatus for op->file[1].
                 */
                op->fetch_status.which = 1;
                op->ops = &afs_lookup_fetch_status_operation;
                afs_begin_vnode_operation(op);
                afs_wait_for_operation(op);
        }

out_op:
        if (!afs_op_error(op)) {
                if (op->file[1].scb.status.abort_code) {
                        afs_op_accumulate_error(op, -ECONNABORTED,
                                                op->file[1].scb.status.abort_code);
                } else {
                        inode = &op->file[1].vnode->netfs.inode;
                        op->file[1].vnode = NULL;
                }
        }

        if (op->file[0].scb.have_status)
                dentry->d_fsdata = (void *)(unsigned long)op->file[0].scb.status.data_version;
        else
                dentry->d_fsdata = (void *)(unsigned long)op->file[0].dv_before;
        ret = afs_put_operation(op);
out:
        kfree(cookie);
        _leave("");
        return inode ?: ERR_PTR(ret);
}

/*
 * Look up an entry in a directory with @sys substitution.
 */
static struct dentry *afs_lookup_atsys(struct inode *dir, struct dentry *dentry)
{
        struct afs_sysnames *subs;
        struct afs_net *net = afs_i2net(dir);
        struct dentry *ret;
        char *buf, *p, *name;
        int len, i;

        _enter("");

        ret = ERR_PTR(-ENOMEM);
        p = buf = kmalloc(AFSNAMEMAX, GFP_KERNEL);
        if (!buf)
                goto out_p;
        if (dentry->d_name.len > 4) {
                memcpy(p, dentry->d_name.name, dentry->d_name.len - 4);
                p += dentry->d_name.len - 4;
        }

        /* There is an ordered list of substitutes that we have to try. */
        read_lock(&net->sysnames_lock);
        subs = net->sysnames;
        refcount_inc(&subs->usage);
        read_unlock(&net->sysnames_lock);

        for (i = 0; i < subs->nr; i++) {
                name = subs->subs[i];
                len = dentry->d_name.len - 4 + strlen(name);
                if (len >= AFSNAMEMAX) {
                        ret = ERR_PTR(-ENAMETOOLONG);
                        goto out_s;
                }

                strcpy(p, name);
                ret = lookup_noperm(&QSTR(buf), dentry->d_parent);
                if (IS_ERR(ret) || d_is_positive(ret))
                        goto out_s;
                dput(ret);
        }

        /* We don't want to d_add() the @sys dentry here as we don't want to
         * the cached dentry to hide changes to the sysnames list.
         */
        ret = NULL;
out_s:
        afs_put_sysnames(subs);
        kfree(buf);
out_p:
        return ret;
}

/*
 * look up an entry in a directory
 */
static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
                                 unsigned int flags)
{
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        struct afs_fid fid = {};
        struct inode *inode;
        struct dentry *d;
        int ret;

        _enter("{%llx:%llu},%p{%pd},",
               dvnode->fid.vid, dvnode->fid.vnode, dentry, dentry);

        ASSERTCMP(d_inode(dentry), ==, NULL);

        if (dentry->d_name.len >= AFSNAMEMAX) {
                _leave(" = -ENAMETOOLONG");
                return ERR_PTR(-ENAMETOOLONG);
        }

        if (test_bit(AFS_VNODE_DELETED, &dvnode->flags)) {
                _leave(" = -ESTALE");
                return ERR_PTR(-ESTALE);
        }

        ret = afs_validate(dvnode, NULL);
        if (ret < 0) {
                afs_dir_unuse_cookie(dvnode, ret);
                _leave(" = %d [val]", ret);
                return ERR_PTR(ret);
        }

        if (dentry->d_name.len >= 4 &&
            dentry->d_name.name[dentry->d_name.len - 4] == '@' &&
            dentry->d_name.name[dentry->d_name.len - 3] == 's' &&
            dentry->d_name.name[dentry->d_name.len - 2] == 'y' &&
            dentry->d_name.name[dentry->d_name.len - 1] == 's')
                return afs_lookup_atsys(dir, dentry);

        afs_stat_v(dvnode, n_lookup);
        inode = afs_do_lookup(dir, dentry);
        if (inode == ERR_PTR(-ENOENT))
                inode = NULL;
        else if (!IS_ERR_OR_NULL(inode))
                fid = AFS_FS_I(inode)->fid;

        _debug("splice %p", dentry->d_inode);
        d = d_splice_alias(inode, dentry);
        if (!IS_ERR_OR_NULL(d)) {
                d->d_fsdata = dentry->d_fsdata;
                trace_afs_lookup(dvnode, &d->d_name, &fid);
        } else {
                trace_afs_lookup(dvnode, &dentry->d_name, &fid);
        }
        _leave("");
        return d;
}

/*
 * Check the validity of a dentry under RCU conditions.
 */
static int afs_d_revalidate_rcu(struct afs_vnode *dvnode, struct dentry *dentry)
{
        long dir_version, de_version;

        _enter("%p", dentry);

        if (test_bit(AFS_VNODE_DELETED, &dvnode->flags))
                return -ECHILD;

        if (!afs_check_validity(dvnode))
                return -ECHILD;

        /* We only need to invalidate a dentry if the server's copy changed
         * behind our back.  If we made the change, it's no problem.  Note that
         * on a 32-bit system, we only have 32 bits in the dentry to store the
         * version.
         */
        dir_version = (long)READ_ONCE(dvnode->status.data_version);
        de_version = (long)READ_ONCE(dentry->d_fsdata);
        if (de_version != dir_version) {
                dir_version = (long)READ_ONCE(dvnode->invalid_before);
                if (de_version - dir_version < 0)
                        return -ECHILD;
        }

        return 1; /* Still valid */
}

/*
 * check that a dentry lookup hit has found a valid entry
 * - NOTE! the hit can be a negative hit too, so we can't assume we have an
 *   inode
 */
static int afs_d_revalidate(struct inode *parent_dir, const struct qstr *name,
                            struct dentry *dentry, unsigned int flags)
{
        struct afs_vnode *vnode, *dir = AFS_FS_I(parent_dir);
        struct afs_fid fid;
        struct inode *inode;
        struct key *key;
        afs_dataversion_t dir_version, invalid_before;
        long de_version;
        int ret;

        if (flags & LOOKUP_RCU)
                return afs_d_revalidate_rcu(dir, dentry);

        if (d_really_is_positive(dentry)) {
                vnode = AFS_FS_I(d_inode(dentry));
                _enter("{v={%llx:%llu} n=%pd fl=%lx},",
                       vnode->fid.vid, vnode->fid.vnode, dentry,
                       vnode->flags);
        } else {
                _enter("{neg n=%pd}", dentry);
        }

        key = afs_request_key(AFS_FS_S(dentry->d_sb)->volume->cell);
        if (IS_ERR(key))
                key = NULL;

        /* validate the parent directory */
        ret = afs_validate(dir, key);
        if (ret == -ERESTARTSYS) {
                key_put(key);
                return ret;
        }

        if (test_bit(AFS_VNODE_DELETED, &dir->flags)) {
                _debug("%pd: parent dir deleted", dentry);
                goto not_found;
        }

        /* We only need to invalidate a dentry if the server's copy changed
         * behind our back.  If we made the change, it's no problem.  Note that
         * on a 32-bit system, we only have 32 bits in the dentry to store the
         * version.
         */
        dir_version = dir->status.data_version;
        de_version = (long)dentry->d_fsdata;
        if (de_version == (long)dir_version)
                goto out_valid_noupdate;

        invalid_before = dir->invalid_before;
        if (de_version - (long)invalid_before >= 0)
                goto out_valid;

        _debug("dir modified");
        afs_stat_v(dir, n_reval);

        /* search the directory for this vnode */
        ret = afs_do_lookup_one(&dir->netfs.inode, name, &fid, &dir_version);
        switch (ret) {
        case 0:
                /* the filename maps to something */
                if (d_really_is_negative(dentry))
                        goto not_found;
                inode = d_inode(dentry);
                if (is_bad_inode(inode)) {
                        printk("kAFS: afs_d_revalidate: %pd2 has bad inode\n",
                               dentry);
                        goto not_found;
                }

                vnode = AFS_FS_I(inode);

                /* if the vnode ID has changed, then the dirent points to a
                 * different file */
                if (fid.vnode != vnode->fid.vnode) {
                        _debug("%pd: dirent changed [%llu != %llu]",
                               dentry, fid.vnode,
                               vnode->fid.vnode);
                        goto not_found;
                }

                /* if the vnode ID uniqifier has changed, then the file has
                 * been deleted and replaced, and the original vnode ID has
                 * been reused */
                if (fid.unique != vnode->fid.unique) {
                        _debug("%pd: file deleted (uq %u -> %u I:%u)",
                               dentry, fid.unique,
                               vnode->fid.unique,
                               vnode->netfs.inode.i_generation);
                        goto not_found;
                }
                goto out_valid;

        case -ENOENT:
                /* the filename is unknown */
                _debug("%pd: dirent not found", dentry);
                if (d_really_is_positive(dentry))
                        goto not_found;
                goto out_valid;

        default:
                _debug("failed to iterate parent %pd2: %d", dentry, ret);
                goto not_found;
        }

out_valid:
        dentry->d_fsdata = (void *)(unsigned long)dir_version;
out_valid_noupdate:
        key_put(key);
        _leave(" = 1 [valid]");
        return 1;

not_found:
        _debug("dropping dentry %pd2", dentry);
        key_put(key);

        _leave(" = 0 [bad]");
        return 0;
}

/*
 * allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
 * sleep)
 * - called from dput() when d_count is going to 0.
 * - return 1 to request dentry be unhashed, 0 otherwise
 */
static int afs_d_delete(const struct dentry *dentry)
{
        _enter("%pd", dentry);

        if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
                goto zap;

        if (d_really_is_positive(dentry) &&
            (test_bit(AFS_VNODE_DELETED,   &AFS_FS_I(d_inode(dentry))->flags) ||
             test_bit(AFS_VNODE_PSEUDODIR, &AFS_FS_I(d_inode(dentry))->flags)))
                goto zap;

        _leave(" = 0 [keep]");
        return 0;

zap:
        _leave(" = 1 [zap]");
        return 1;
}

/*
 * Clean up sillyrename files on dentry removal.
 */
static void afs_d_iput(struct dentry *dentry, struct inode *inode)
{
        if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
                afs_silly_iput(dentry, inode);
        iput(inode);
}

/*
 * handle dentry release
 */
void afs_d_release(struct dentry *dentry)
{
        _enter("%pd", dentry);
}

void afs_check_for_remote_deletion(struct afs_operation *op)
{
        struct afs_vnode *vnode = op->file[0].vnode;

        switch (afs_op_abort_code(op)) {
        case VNOVNODE:
                set_bit(AFS_VNODE_DELETED, &vnode->flags);
                clear_nlink(&vnode->netfs.inode);
                afs_break_callback(vnode, afs_cb_break_for_deleted);
        }
}

/*
 * Create a new inode for create/mkdir/symlink
 */
static void afs_vnode_new_inode(struct afs_operation *op)
{
        struct afs_vnode_param *dvp = &op->file[0];
        struct afs_vnode_param *vp = &op->file[1];
        struct afs_vnode *vnode;
        struct inode *inode;

        _enter("");

        ASSERTCMP(afs_op_error(op), ==, 0);

        inode = afs_iget(op, vp);
        if (IS_ERR(inode)) {
                /* ENOMEM or EINTR at a really inconvenient time - just abandon
                 * the new directory on the server.
                 */
                afs_op_accumulate_error(op, PTR_ERR(inode), 0);
                return;
        }

        vnode = AFS_FS_I(inode);
        set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
        if (S_ISDIR(inode->i_mode))
                afs_mkdir_init_dir(vnode, dvp->vnode);
        else if (S_ISLNK(inode->i_mode))
                afs_init_new_symlink(vnode, op);
        if (!afs_op_error(op))
                afs_cache_permit(vnode, op->key, vnode->cb_break, &vp->scb);
        d_instantiate(op->dentry, inode);
}

static void afs_create_success(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);
        op->ctime = op->file[0].scb.status.mtime_client;
        afs_vnode_commit_status(op, &op->file[0]);
        afs_update_dentry_version(op, &op->file[0], op->dentry);
        afs_vnode_new_inode(op);
}

static void afs_create_edit_dir(struct afs_operation *op)
{
        struct netfs_cache_resources cres = {};
        struct afs_vnode_param *dvp = &op->file[0];
        struct afs_vnode_param *vp = &op->file[1];
        struct afs_vnode *dvnode = dvp->vnode;

        _enter("op=%08x", op->debug_id);

        fscache_begin_write_operation(&cres, afs_vnode_cache(dvnode));
        down_write(&dvnode->validate_lock);
        if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
            dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
                afs_edit_dir_add(dvnode, &op->dentry->d_name, &vp->fid,
                                 op->create.reason);
        up_write(&dvnode->validate_lock);
        fscache_end_operation(&cres);
}

static void afs_create_put(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);

        if (afs_op_error(op))
                d_drop(op->dentry);
}

static const struct afs_operation_ops afs_mkdir_operation = {
        .issue_afs_rpc  = afs_fs_make_dir,
        .issue_yfs_rpc  = yfs_fs_make_dir,
        .success        = afs_create_success,
        .aborted        = afs_check_for_remote_deletion,
        .edit_dir       = afs_create_edit_dir,
        .put            = afs_create_put,
};

/*
 * create a directory on an AFS filesystem
 */
static struct dentry *afs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
                                struct dentry *dentry, umode_t mode)
{
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        int ret;

        _enter("{%llx:%llu},{%pd},%ho",
               dvnode->fid.vid, dvnode->fid.vnode, dentry, mode);

        op = afs_alloc_operation(NULL, dvnode->volume);
        if (IS_ERR(op)) {
                d_drop(dentry);
                return ERR_CAST(op);
        }

        fscache_use_cookie(afs_vnode_cache(dvnode), true);

        afs_op_set_vnode(op, 0, dvnode);
        op->file[0].dv_delta = 1;
        op->file[0].modification = true;
        op->file[0].update_ctime = true;
        op->dentry      = dentry;
        op->create.mode = S_IFDIR | mode;
        op->create.reason = afs_edit_dir_for_mkdir;
        op->mtime       = current_time(dir);
        op->ops         = &afs_mkdir_operation;
        ret = afs_do_sync_operation(op);
        afs_dir_unuse_cookie(dvnode, ret);
        return ERR_PTR(ret);
}

/*
 * Remove a subdir from a directory.
 */
static void afs_dir_remove_subdir(struct dentry *dentry)
{
        if (d_really_is_positive(dentry)) {
                struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));

                clear_nlink(&vnode->netfs.inode);
                set_bit(AFS_VNODE_DELETED, &vnode->flags);
                afs_clear_cb_promise(vnode, afs_cb_promise_clear_rmdir);
                afs_invalidate_dir(vnode, afs_dir_invalid_subdir_removed);
        }
}

static void afs_rmdir_success(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);
        op->ctime = op->file[0].scb.status.mtime_client;
        afs_vnode_commit_status(op, &op->file[0]);
        afs_update_dentry_version(op, &op->file[0], op->dentry);
}

static void afs_rmdir_edit_dir(struct afs_operation *op)
{
        struct netfs_cache_resources cres = {};
        struct afs_vnode_param *dvp = &op->file[0];
        struct afs_vnode *dvnode = dvp->vnode;

        _enter("op=%08x", op->debug_id);
        afs_dir_remove_subdir(op->dentry);

        fscache_begin_write_operation(&cres, afs_vnode_cache(dvnode));
        down_write(&dvnode->validate_lock);
        if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
            dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
                afs_edit_dir_remove(dvnode, &op->dentry->d_name,
                                    afs_edit_dir_for_rmdir);
        up_write(&dvnode->validate_lock);
        fscache_end_operation(&cres);
}

static void afs_rmdir_put(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);
        if (op->file[1].vnode)
                up_write(&op->file[1].vnode->rmdir_lock);
}

static const struct afs_operation_ops afs_rmdir_operation = {
        .issue_afs_rpc  = afs_fs_remove_dir,
        .issue_yfs_rpc  = yfs_fs_remove_dir,
        .success        = afs_rmdir_success,
        .aborted        = afs_check_for_remote_deletion,
        .edit_dir       = afs_rmdir_edit_dir,
        .put            = afs_rmdir_put,
};

/*
 * remove a directory from an AFS filesystem
 */
static int afs_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir), *vnode = NULL;
        int ret;

        _enter("{%llx:%llu},{%pd}",
               dvnode->fid.vid, dvnode->fid.vnode, dentry);

        op = afs_alloc_operation(NULL, dvnode->volume);
        if (IS_ERR(op))
                return PTR_ERR(op);

        fscache_use_cookie(afs_vnode_cache(dvnode), true);

        afs_op_set_vnode(op, 0, dvnode);
        op->file[0].dv_delta = 1;
        op->file[0].modification = true;
        op->file[0].update_ctime = true;

        op->dentry      = dentry;
        op->ops         = &afs_rmdir_operation;

        /* Try to make sure we have a callback promise on the victim. */
        if (d_really_is_positive(dentry)) {
                vnode = AFS_FS_I(d_inode(dentry));
                ret = afs_validate(vnode, op->key);
                if (ret < 0)
                        goto error;
        }

        if (vnode) {
                ret = down_write_killable(&vnode->rmdir_lock);
                if (ret < 0)
                        goto error;
                op->file[1].vnode = vnode;
        }

        ret = afs_do_sync_operation(op);

        /* Not all systems that can host afs servers have ENOTEMPTY. */
        if (ret == -EEXIST)
                ret = -ENOTEMPTY;
out:
        afs_dir_unuse_cookie(dvnode, ret);
        return ret;

error:
        ret = afs_put_operation(op);
        goto out;
}

/*
 * Remove a link to a file or symlink from a directory.
 *
 * If the file was not deleted due to excess hard links, the fileserver will
 * break the callback promise on the file - if it had one - before it returns
 * to us, and if it was deleted, it won't
 *
 * However, if we didn't have a callback promise outstanding, or it was
 * outstanding on a different server, then it won't break it either...
 */
static void afs_dir_remove_link(struct afs_operation *op)
{
        struct afs_vnode *dvnode = op->file[0].vnode;
        struct afs_vnode *vnode = op->file[1].vnode;
        struct dentry *dentry = op->dentry;
        int ret;

        if (afs_op_error(op) ||
            (op->file[1].scb.have_status && op->file[1].scb.have_error))
                return;
        if (d_really_is_positive(dentry))
                return;

        if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
                /* Already done */
        } else if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags)) {
                write_seqlock(&vnode->cb_lock);
                drop_nlink(&vnode->netfs.inode);
                if (vnode->netfs.inode.i_nlink == 0) {
                        set_bit(AFS_VNODE_DELETED, &vnode->flags);
                        __afs_break_callback(vnode, afs_cb_break_for_unlink);
                }
                write_sequnlock(&vnode->cb_lock);
        } else {
                afs_break_callback(vnode, afs_cb_break_for_unlink);

                if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
                        _debug("AFS_VNODE_DELETED");

                ret = afs_validate(vnode, op->key);
                if (ret != -ESTALE)
                        afs_op_set_error(op, ret);
        }

        _debug("nlink %d [val %d]", vnode->netfs.inode.i_nlink, afs_op_error(op));
}

static void afs_unlink_success(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);
        op->ctime = op->file[0].scb.status.mtime_client;
        afs_check_dir_conflict(op, &op->file[0]);
        afs_vnode_commit_status(op, &op->file[0]);
        afs_vnode_commit_status(op, &op->file[1]);
        afs_update_dentry_version(op, &op->file[0], op->dentry);
        afs_dir_remove_link(op);
}

static void afs_unlink_edit_dir(struct afs_operation *op)
{
        struct netfs_cache_resources cres = {};
        struct afs_vnode_param *dvp = &op->file[0];
        struct afs_vnode *dvnode = dvp->vnode;

        _enter("op=%08x", op->debug_id);
        fscache_begin_write_operation(&cres, afs_vnode_cache(dvnode));
        down_write(&dvnode->validate_lock);
        if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
            dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
                afs_edit_dir_remove(dvnode, &op->dentry->d_name,
                                    afs_edit_dir_for_unlink);
        up_write(&dvnode->validate_lock);
        fscache_end_operation(&cres);
}

static void afs_unlink_put(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);
        if (op->unlink.need_rehash && afs_op_error(op) < 0 && afs_op_error(op) != -ENOENT)
                d_rehash(op->dentry);
}

static const struct afs_operation_ops afs_unlink_operation = {
        .issue_afs_rpc  = afs_fs_remove_file,
        .issue_yfs_rpc  = yfs_fs_remove_file,
        .success        = afs_unlink_success,
        .aborted        = afs_check_for_remote_deletion,
        .edit_dir       = afs_unlink_edit_dir,
        .put            = afs_unlink_put,
};

/*
 * Remove a file or symlink from an AFS filesystem.
 */
static int afs_unlink(struct inode *dir, struct dentry *dentry)
{
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
        int ret;

        _enter("{%llx:%llu},{%pd}",
               dvnode->fid.vid, dvnode->fid.vnode, dentry);

        if (dentry->d_name.len >= AFSNAMEMAX)
                return -ENAMETOOLONG;

        op = afs_alloc_operation(NULL, dvnode->volume);
        if (IS_ERR(op))
                return PTR_ERR(op);

        fscache_use_cookie(afs_vnode_cache(dvnode), true);

        afs_op_set_vnode(op, 0, dvnode);
        op->file[0].dv_delta = 1;
        op->file[0].modification = true;
        op->file[0].update_ctime = true;

        /* Try to make sure we have a callback promise on the victim. */
        ret = afs_validate(vnode, op->key);
        if (ret < 0) {
                afs_op_set_error(op, ret);
                goto error;
        }

        spin_lock(&dentry->d_lock);
        if (d_count(dentry) > 1) {
                spin_unlock(&dentry->d_lock);
                /* Start asynchronous writeout of the inode */
                write_inode_now(d_inode(dentry), 0);
                afs_op_set_error(op, afs_sillyrename(dvnode, vnode, dentry, op->key));
                goto error;
        }
        if (!d_unhashed(dentry)) {
                /* Prevent a race with RCU lookup. */
                __d_drop(dentry);
                op->unlink.need_rehash = true;
        }
        spin_unlock(&dentry->d_lock);

        op->file[1].vnode = vnode;
        op->file[1].update_ctime = true;
        op->file[1].op_unlinked = true;
        op->dentry      = dentry;
        op->ops         = &afs_unlink_operation;
        afs_begin_vnode_operation(op);
        afs_wait_for_operation(op);

        /* If there was a conflict with a third party, check the status of the
         * unlinked vnode.
         */
        if (afs_op_error(op) == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
                op->file[1].update_ctime = false;
                op->fetch_status.which = 1;
                op->ops = &afs_fetch_status_operation;
                afs_begin_vnode_operation(op);
                afs_wait_for_operation(op);
        }

error:
        ret = afs_put_operation(op);
        afs_dir_unuse_cookie(dvnode, ret);
        return ret;
}

static const struct afs_operation_ops afs_create_operation = {
        .issue_afs_rpc  = afs_fs_create_file,
        .issue_yfs_rpc  = yfs_fs_create_file,
        .success        = afs_create_success,
        .aborted        = afs_check_for_remote_deletion,
        .edit_dir       = afs_create_edit_dir,
        .put            = afs_create_put,
};

/*
 * create a regular file on an AFS filesystem
 */
static int afs_create(struct mnt_idmap *idmap, struct inode *dir,
                      struct dentry *dentry, umode_t mode, bool excl)
{
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        int ret = -ENAMETOOLONG;

        _enter("{%llx:%llu},{%pd},%ho",
               dvnode->fid.vid, dvnode->fid.vnode, dentry, mode);

        if (dentry->d_name.len >= AFSNAMEMAX)
                goto error;

        op = afs_alloc_operation(NULL, dvnode->volume);
        if (IS_ERR(op)) {
                ret = PTR_ERR(op);
                goto error;
        }

        fscache_use_cookie(afs_vnode_cache(dvnode), true);

        afs_op_set_vnode(op, 0, dvnode);
        op->file[0].dv_delta = 1;
        op->file[0].modification = true;
        op->file[0].update_ctime = true;

        op->dentry      = dentry;
        op->create.mode = S_IFREG | mode;
        op->create.reason = afs_edit_dir_for_create;
        op->mtime       = current_time(dir);
        op->ops         = &afs_create_operation;
        ret = afs_do_sync_operation(op);
        afs_dir_unuse_cookie(dvnode, ret);
        return ret;

error:
        d_drop(dentry);
        _leave(" = %d", ret);
        return ret;
}

static void afs_link_success(struct afs_operation *op)
{
        struct afs_vnode_param *dvp = &op->file[0];
        struct afs_vnode_param *vp = &op->file[1];

        _enter("op=%08x", op->debug_id);
        op->ctime = dvp->scb.status.mtime_client;
        afs_vnode_commit_status(op, dvp);
        afs_vnode_commit_status(op, vp);
        afs_update_dentry_version(op, dvp, op->dentry);
        if (op->dentry_2->d_parent == op->dentry->d_parent)
                afs_update_dentry_version(op, dvp, op->dentry_2);
        ihold(&vp->vnode->netfs.inode);
        d_instantiate(op->dentry, &vp->vnode->netfs.inode);
}

static void afs_link_put(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);
        if (afs_op_error(op))
                d_drop(op->dentry);
}

static const struct afs_operation_ops afs_link_operation = {
        .issue_afs_rpc  = afs_fs_link,
        .issue_yfs_rpc  = yfs_fs_link,
        .success        = afs_link_success,
        .aborted        = afs_check_for_remote_deletion,
        .edit_dir       = afs_create_edit_dir,
        .put            = afs_link_put,
};

/*
 * create a hard link between files in an AFS filesystem
 */
static int afs_link(struct dentry *from, struct inode *dir,
                    struct dentry *dentry)
{
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        struct afs_vnode *vnode = AFS_FS_I(d_inode(from));
        int ret = -ENAMETOOLONG;

        _enter("{%llx:%llu},{%llx:%llu},{%pd}",
               vnode->fid.vid, vnode->fid.vnode,
               dvnode->fid.vid, dvnode->fid.vnode,
               dentry);

        if (dentry->d_name.len >= AFSNAMEMAX)
                goto error;

        op = afs_alloc_operation(NULL, dvnode->volume);
        if (IS_ERR(op)) {
                ret = PTR_ERR(op);
                goto error;
        }

        fscache_use_cookie(afs_vnode_cache(dvnode), true);

        ret = afs_validate(vnode, op->key);
        if (ret < 0)
                goto error_op;

        afs_op_set_vnode(op, 0, dvnode);
        afs_op_set_vnode(op, 1, vnode);
        op->file[0].dv_delta = 1;
        op->file[0].modification = true;
        op->file[0].update_ctime = true;
        op->file[1].update_ctime = true;

        op->dentry              = dentry;
        op->dentry_2            = from;
        op->ops                 = &afs_link_operation;
        op->create.reason       = afs_edit_dir_for_link;
        ret = afs_do_sync_operation(op);
        afs_dir_unuse_cookie(dvnode, ret);
        return ret;

error_op:
        afs_put_operation(op);
        afs_dir_unuse_cookie(dvnode, ret);
error:
        d_drop(dentry);
        _leave(" = %d", ret);
        return ret;
}

static const struct afs_operation_ops afs_symlink_operation = {
        .issue_afs_rpc  = afs_fs_symlink,
        .issue_yfs_rpc  = yfs_fs_symlink,
        .success        = afs_create_success,
        .aborted        = afs_check_for_remote_deletion,
        .edit_dir       = afs_create_edit_dir,
        .put            = afs_create_put,
};

/*
 * create a symlink in an AFS filesystem
 */
static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir,
                       struct dentry *dentry, const char *content)
{
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        int ret;

        _enter("{%llx:%llu},{%pd},%s",
               dvnode->fid.vid, dvnode->fid.vnode, dentry,
               content);

        ret = -ENAMETOOLONG;
        if (dentry->d_name.len >= AFSNAMEMAX)
                goto error;

        ret = -EINVAL;
        if (strlen(content) >= AFSPATHMAX)
                goto error;

        op = afs_alloc_operation(NULL, dvnode->volume);
        if (IS_ERR(op)) {
                ret = PTR_ERR(op);
                goto error;
        }

        fscache_use_cookie(afs_vnode_cache(dvnode), true);

        afs_op_set_vnode(op, 0, dvnode);
        op->file[0].dv_delta = 1;

        op->dentry              = dentry;
        op->ops                 = &afs_symlink_operation;
        op->create.reason       = afs_edit_dir_for_symlink;
        op->create.symlink      = content;
        op->mtime               = current_time(dir);
        ret = afs_do_sync_operation(op);
        afs_dir_unuse_cookie(dvnode, ret);
        return ret;

error:
        d_drop(dentry);
        _leave(" = %d", ret);
        return ret;
}

static void afs_rename_success(struct afs_operation *op)
{
        struct afs_vnode *vnode = op->more_files[0].vnode;
        struct afs_vnode *new_vnode = op->more_files[1].vnode;

        _enter("op=%08x", op->debug_id);

        op->ctime = op->file[0].scb.status.mtime_client;
        afs_check_dir_conflict(op, &op->file[1]);
        afs_vnode_commit_status(op, &op->file[0]);
        if (op->file[1].vnode != op->file[0].vnode) {
                op->ctime = op->file[1].scb.status.mtime_client;
                afs_vnode_commit_status(op, &op->file[1]);
        }
        if (op->more_files[0].scb.have_status)
                afs_vnode_commit_status(op, &op->more_files[0]);
        if (op->more_files[1].scb.have_status)
                afs_vnode_commit_status(op, &op->more_files[1]);

        /* If we're moving a subdir between dirs, we need to update
         * its DV counter too as the ".." will be altered.
         */
        if (op->file[0].vnode != op->file[1].vnode) {
                if (S_ISDIR(vnode->netfs.inode.i_mode)) {
                        u64 new_dv;

                        write_seqlock(&vnode->cb_lock);

                        new_dv = vnode->status.data_version + 1;
                        trace_afs_set_dv(vnode, new_dv);
                        vnode->status.data_version = new_dv;
                        inode_set_iversion_raw(&vnode->netfs.inode, new_dv);

                        write_sequnlock(&vnode->cb_lock);
                }

                if ((op->rename.rename_flags & RENAME_EXCHANGE) &&
                    S_ISDIR(new_vnode->netfs.inode.i_mode)) {
                        u64 new_dv;

                        write_seqlock(&new_vnode->cb_lock);

                        new_dv = new_vnode->status.data_version + 1;
                        new_vnode->status.data_version = new_dv;
                        inode_set_iversion_raw(&new_vnode->netfs.inode, new_dv);

                        write_sequnlock(&new_vnode->cb_lock);
                }
        }
}

static void afs_rename_edit_dir(struct afs_operation *op)
{
        struct netfs_cache_resources orig_cres = {}, new_cres = {};
        struct afs_vnode_param *orig_dvp = &op->file[0];
        struct afs_vnode_param *new_dvp = &op->file[1];
        struct afs_vnode *orig_dvnode = orig_dvp->vnode;
        struct afs_vnode *new_dvnode = new_dvp->vnode;
        struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry));
        struct dentry *old_dentry = op->dentry;
        struct dentry *new_dentry = op->dentry_2;
        struct inode *new_inode;

        _enter("op=%08x", op->debug_id);

        if (op->rename.rehash) {
                d_rehash(op->rename.rehash);
                op->rename.rehash = NULL;
        }

        fscache_begin_write_operation(&orig_cres, afs_vnode_cache(orig_dvnode));
        if (new_dvnode != orig_dvnode)
                fscache_begin_write_operation(&new_cres, afs_vnode_cache(new_dvnode));

        down_write(&orig_dvnode->validate_lock);
        if (test_bit(AFS_VNODE_DIR_VALID, &orig_dvnode->flags) &&
            orig_dvnode->status.data_version == orig_dvp->dv_before + orig_dvp->dv_delta)
                afs_edit_dir_remove(orig_dvnode, &old_dentry->d_name,
                                    afs_edit_dir_for_rename_0);

        if (new_dvnode != orig_dvnode) {
                up_write(&orig_dvnode->validate_lock);
                down_write(&new_dvnode->validate_lock);
        }

        if (test_bit(AFS_VNODE_DIR_VALID, &new_dvnode->flags) &&
            new_dvnode->status.data_version == new_dvp->dv_before + new_dvp->dv_delta) {
                if (!op->rename.new_negative)
                        afs_edit_dir_remove(new_dvnode, &new_dentry->d_name,
                                            afs_edit_dir_for_rename_1);

                afs_edit_dir_add(new_dvnode, &new_dentry->d_name,
                                 &vnode->fid, afs_edit_dir_for_rename_2);
        }

        if (S_ISDIR(vnode->netfs.inode.i_mode) &&
            new_dvnode != orig_dvnode &&
            test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
                afs_edit_dir_update(vnode, &dotdot_name, new_dvnode,
                                    afs_edit_dir_for_rename_sub);

        new_inode = d_inode(new_dentry);
        if (new_inode) {
                spin_lock(&new_inode->i_lock);
                if (S_ISDIR(new_inode->i_mode))
                        clear_nlink(new_inode);
                else if (new_inode->i_nlink > 0)
                        drop_nlink(new_inode);
                spin_unlock(&new_inode->i_lock);
        }

        /* Now we can update d_fsdata on the dentries to reflect their
         * new parent's data_version.
         */
        afs_update_dentry_version(op, new_dvp, op->dentry);
        afs_update_dentry_version(op, new_dvp, op->dentry_2);

        d_move(old_dentry, new_dentry);

        up_write(&new_dvnode->validate_lock);
        fscache_end_operation(&orig_cres);
        if (new_dvnode != orig_dvnode)
                fscache_end_operation(&new_cres);
}

static void afs_rename_exchange_edit_dir(struct afs_operation *op)
{
        struct afs_vnode_param *orig_dvp = &op->file[0];
        struct afs_vnode_param *new_dvp = &op->file[1];
        struct afs_vnode *orig_dvnode = orig_dvp->vnode;
        struct afs_vnode *new_dvnode = new_dvp->vnode;
        struct afs_vnode *old_vnode = op->more_files[0].vnode;
        struct afs_vnode *new_vnode = op->more_files[1].vnode;
        struct dentry *old_dentry = op->dentry;
        struct dentry *new_dentry = op->dentry_2;

        _enter("op=%08x", op->debug_id);

        if (new_dvnode == orig_dvnode) {
                down_write(&orig_dvnode->validate_lock);
                if (test_bit(AFS_VNODE_DIR_VALID, &orig_dvnode->flags) &&
                    orig_dvnode->status.data_version == orig_dvp->dv_before + orig_dvp->dv_delta) {
                        afs_edit_dir_update(orig_dvnode, &old_dentry->d_name,
                                            new_vnode, afs_edit_dir_for_rename_0);
                        afs_edit_dir_update(orig_dvnode, &new_dentry->d_name,
                                            old_vnode, afs_edit_dir_for_rename_1);
                }

                d_exchange(old_dentry, new_dentry);
                up_write(&orig_dvnode->validate_lock);
        } else {
                down_write(&orig_dvnode->validate_lock);
                if (test_bit(AFS_VNODE_DIR_VALID, &orig_dvnode->flags) &&
                    orig_dvnode->status.data_version == orig_dvp->dv_before + orig_dvp->dv_delta)
                        afs_edit_dir_update(orig_dvnode, &old_dentry->d_name,
                                            new_vnode, afs_edit_dir_for_rename_0);

                up_write(&orig_dvnode->validate_lock);
                down_write(&new_dvnode->validate_lock);

                if (test_bit(AFS_VNODE_DIR_VALID, &new_dvnode->flags) &&
                    new_dvnode->status.data_version == new_dvp->dv_before + new_dvp->dv_delta)
                        afs_edit_dir_update(new_dvnode, &new_dentry->d_name,
                                            old_vnode, afs_edit_dir_for_rename_1);

                if (S_ISDIR(old_vnode->netfs.inode.i_mode) &&
                    test_bit(AFS_VNODE_DIR_VALID, &old_vnode->flags))
                        afs_edit_dir_update(old_vnode, &dotdot_name, new_dvnode,
                                            afs_edit_dir_for_rename_sub);

                if (S_ISDIR(new_vnode->netfs.inode.i_mode) &&
                    test_bit(AFS_VNODE_DIR_VALID, &new_vnode->flags))
                        afs_edit_dir_update(new_vnode, &dotdot_name, orig_dvnode,
                                            afs_edit_dir_for_rename_sub);

                /* Now we can update d_fsdata on the dentries to reflect their
                 * new parents' data_version.
                 */
                afs_update_dentry_version(op, new_dvp, old_dentry);
                afs_update_dentry_version(op, orig_dvp, new_dentry);

                d_exchange(old_dentry, new_dentry);
                up_write(&new_dvnode->validate_lock);
        }
}

static void afs_rename_put(struct afs_operation *op)
{
        _enter("op=%08x", op->debug_id);
        if (op->rename.rehash)
                d_rehash(op->rename.rehash);
        dput(op->rename.tmp);
        if (afs_op_error(op))
                d_rehash(op->dentry);
}

static const struct afs_operation_ops afs_rename_operation = {
        .issue_afs_rpc  = afs_fs_rename,
        .issue_yfs_rpc  = yfs_fs_rename,
        .success        = afs_rename_success,
        .edit_dir       = afs_rename_edit_dir,
        .put            = afs_rename_put,
};

#if 0 /* Autoswitched in yfs_fs_rename_replace(). */
static const struct afs_operation_ops afs_rename_replace_operation = {
        .issue_afs_rpc  = NULL,
        .issue_yfs_rpc  = yfs_fs_rename_replace,
        .success        = afs_rename_success,
        .edit_dir       = afs_rename_edit_dir,
        .put            = afs_rename_put,
};
#endif

static const struct afs_operation_ops afs_rename_noreplace_operation = {
        .issue_afs_rpc  = NULL,
        .issue_yfs_rpc  = yfs_fs_rename_noreplace,
        .success        = afs_rename_success,
        .edit_dir       = afs_rename_edit_dir,
        .put            = afs_rename_put,
};

static const struct afs_operation_ops afs_rename_exchange_operation = {
        .issue_afs_rpc  = NULL,
        .issue_yfs_rpc  = yfs_fs_rename_exchange,
        .success        = afs_rename_success,
        .edit_dir       = afs_rename_exchange_edit_dir,
        .put            = afs_rename_put,
};

/*
 * rename a file in an AFS filesystem and/or move it between directories
 */
static int afs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
                      struct dentry *old_dentry, struct inode *new_dir,
                      struct dentry *new_dentry, unsigned int flags)
{
        struct afs_operation *op;
        struct afs_vnode *orig_dvnode, *new_dvnode, *vnode, *new_vnode = NULL;
        int ret;

        if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
                return -EINVAL;

        /* Don't allow silly-rename files be moved around. */
        if (old_dentry->d_flags & DCACHE_NFSFS_RENAMED)
                return -EINVAL;

        vnode = AFS_FS_I(d_inode(old_dentry));
        orig_dvnode = AFS_FS_I(old_dir);
        new_dvnode = AFS_FS_I(new_dir);
        if (d_is_positive(new_dentry))
                new_vnode = AFS_FS_I(d_inode(new_dentry));

        _enter("{%llx:%llu},{%llx:%llu},{%llx:%llu},{%pd}",
               orig_dvnode->fid.vid, orig_dvnode->fid.vnode,
               vnode->fid.vid, vnode->fid.vnode,
               new_dvnode->fid.vid, new_dvnode->fid.vnode,
               new_dentry);

        op = afs_alloc_operation(NULL, orig_dvnode->volume);
        if (IS_ERR(op))
                return PTR_ERR(op);

        fscache_use_cookie(afs_vnode_cache(orig_dvnode), true);
        if (new_dvnode != orig_dvnode)
                fscache_use_cookie(afs_vnode_cache(new_dvnode), true);

        ret = afs_validate(vnode, op->key);
        afs_op_set_error(op, ret);
        if (ret < 0)
                goto error;

        ret = -ENOMEM;
        op->more_files = kvzalloc_objs(struct afs_vnode_param, 2);
        if (!op->more_files)
                goto error;

        afs_op_set_vnode(op, 0, orig_dvnode);
        afs_op_set_vnode(op, 1, new_dvnode); /* May be same as orig_dvnode */
        op->file[0].dv_delta = 1;
        op->file[1].dv_delta = 1;
        op->file[0].modification = true;
        op->file[1].modification = true;
        op->file[0].update_ctime = true;
        op->file[1].update_ctime = true;
        op->more_files[0].vnode         = vnode;
        op->more_files[0].speculative   = true;
        op->more_files[1].vnode         = new_vnode;
        op->more_files[1].speculative   = true;
        op->nr_files = 4;

        op->dentry              = old_dentry;
        op->dentry_2            = new_dentry;
        op->rename.rename_flags = flags;
        op->rename.new_negative = d_is_negative(new_dentry);

        if (flags & RENAME_NOREPLACE) {
                op->ops         = &afs_rename_noreplace_operation;
        } else if (flags & RENAME_EXCHANGE) {
                op->ops         = &afs_rename_exchange_operation;
                d_drop(new_dentry);
        } else {
                /* If we might displace the target, we might need to do silly
                 * rename.
                 */
                op->ops = &afs_rename_operation;

                /* For non-directories, check whether the target is busy and if
                 * so, make a copy of the dentry and then do a silly-rename.
                 * If the silly-rename succeeds, the copied dentry is hashed
                 * and becomes the new target.
                 */
                if (d_is_positive(new_dentry) && !d_is_dir(new_dentry)) {
                        /* To prevent any new references to the target during
                         * the rename, we unhash the dentry in advance.
                         */
                        if (!d_unhashed(new_dentry)) {
                                d_drop(new_dentry);
                                op->rename.rehash = new_dentry;
                        }

                        if (d_count(new_dentry) > 2) {
                                /* copy the target dentry's name */
                                op->rename.tmp = d_alloc(new_dentry->d_parent,
                                                         &new_dentry->d_name);
                                if (!op->rename.tmp) {
                                        afs_op_nomem(op);
                                        goto error;
                                }

                                ret = afs_sillyrename(new_dvnode,
                                                      AFS_FS_I(d_inode(new_dentry)),
                                                      new_dentry, op->key);
                                if (ret) {
                                        afs_op_set_error(op, ret);
                                        goto error;
                                }

                                op->dentry_2 = op->rename.tmp;
                                op->rename.rehash = NULL;
                                op->rename.new_negative = true;
                        }
                }
        }

        /* This bit is potentially nasty as there's a potential race with
         * afs_d_revalidate{,_rcu}().  We have to change d_fsdata on the dentry
         * to reflect it's new parent's new data_version after the op, but
         * d_revalidate may see old_dentry between the op having taken place
         * and the version being updated.
         *
         * So drop the old_dentry for now to make other threads go through
         * lookup instead - which we hold a lock against.
         */
        d_drop(old_dentry);

        ret = afs_do_sync_operation(op);
        if (ret == -ENOTSUPP)
                ret = -EINVAL;
out:
        afs_dir_unuse_cookie(orig_dvnode, ret);
        if (new_dvnode != orig_dvnode)
                afs_dir_unuse_cookie(new_dvnode, ret);
        return ret;

error:
        ret = afs_put_operation(op);
        goto out;
}

/*
 * Write the file contents to the cache as a single blob.
 */
int afs_single_writepages(struct address_space *mapping,
                          struct writeback_control *wbc)
{
        struct afs_vnode *dvnode = AFS_FS_I(mapping->host);
        struct iov_iter iter;
        bool is_dir = (S_ISDIR(dvnode->netfs.inode.i_mode) &&
                       !test_bit(AFS_VNODE_MOUNTPOINT, &dvnode->flags));
        int ret = 0;

        /* Need to lock to prevent the folio queue and folios from being thrown
         * away.
         */
        down_read(&dvnode->validate_lock);

        if (is_dir ?
            test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) :
            atomic64_read(&dvnode->cb_expires_at) != AFS_NO_CB_PROMISE) {
                iov_iter_folio_queue(&iter, ITER_SOURCE, dvnode->directory, 0, 0,
                                     i_size_read(&dvnode->netfs.inode));
                ret = netfs_writeback_single(mapping, wbc, &iter);
        }

        up_read(&dvnode->validate_lock);
        return ret;
}