// 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/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 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 int afs_lookup_one_filldir(struct dir_context *ctx, const char *name, int nlen,
                                  loff_t fpos, u64 ino, unsigned dtype);
static int afs_lookup_filldir(struct dir_context *ctx, const char *name, int nlen,
                              loff_t fpos, u64 ino, unsigned dtype);
static int afs_create(struct user_namespace *mnt_userns, struct inode *dir,
                      struct dentry *dentry, umode_t mode, bool excl);
static int afs_mkdir(struct user_namespace *mnt_userns, 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 user_namespace *mnt_userns, struct inode *dir,
                       struct dentry *dentry, const char *content);
static int afs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
                      struct dentry *old_dentry, struct inode *new_dir,
                      struct dentry *new_dentry, unsigned int flags);
static int afs_dir_releasepage(struct page *page, gfp_t gfp_flags);
static void afs_dir_invalidatepage(struct page *page, unsigned int offset,
                                   unsigned int length);

static int afs_dir_set_page_dirty(struct page *page)
{
        BUG(); /* This should never happen. */
}

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 = {
        .set_page_dirty = afs_dir_set_page_dirty,
        .releasepage    = afs_dir_releasepage,
        .invalidatepage = afs_dir_invalidatepage,
};

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;
        bool                    found;
        bool                    one_only;
        unsigned short          nr_fids;
        struct afs_fid          fids[50];
};

/*
 * Drop the refs that we're holding on the pages we were reading into.  We've
 * got refs on the first nr_pages pages.
 */
static void afs_dir_read_cleanup(struct afs_read *req)
{
        struct address_space *mapping = req->vnode->vfs_inode.i_mapping;
        struct page *page;
        pgoff_t last = req->nr_pages - 1;

        XA_STATE(xas, &mapping->i_pages, 0);

        if (unlikely(!req->nr_pages))
                return;

        rcu_read_lock();
        xas_for_each(&xas, page, last) {
                if (xas_retry(&xas, page))
                        continue;
                BUG_ON(xa_is_value(page));
                BUG_ON(PageCompound(page));
                ASSERTCMP(page->mapping, ==, mapping);

                put_page(page);
        }

        rcu_read_unlock();
}

/*
 * check that a directory page is valid
 */
static bool afs_dir_check_page(struct afs_vnode *dvnode, struct page *page,
                               loff_t i_size)
{
        struct afs_xdr_dir_page *dbuf;
        loff_t latter, off;
        int tmp, qty;

        /* Determine how many magic numbers there should be in this page, but
         * we must take care because the directory may change size under us.
         */
        off = page_offset(page);
        if (i_size <= off)
                goto checked;

        latter = i_size - off;
        if (latter >= PAGE_SIZE)
                qty = PAGE_SIZE;
        else
                qty = latter;
        qty /= sizeof(union afs_xdr_dir_block);

        /* check them */
        dbuf = kmap_atomic(page);
        for (tmp = 0; tmp < qty; tmp++) {
                if (dbuf->blocks[tmp].hdr.magic != AFS_DIR_MAGIC) {
                        printk("kAFS: %s(%lx): bad magic %d/%d is %04hx\n",
                               __func__, dvnode->vfs_inode.i_ino, tmp, qty,
                               ntohs(dbuf->blocks[tmp].hdr.magic));
                        trace_afs_dir_check_failed(dvnode, off, i_size);
                        kunmap(page);
                        trace_afs_file_error(dvnode, -EIO, afs_file_error_dir_bad_magic);
                        goto error;
                }

                /* Make sure each block is NUL terminated so we can reasonably
                 * use string functions on it.  The filenames in the page
                 * *should* be NUL-terminated anyway.
                 */
                ((u8 *)&dbuf->blocks[tmp])[AFS_DIR_BLOCK_SIZE - 1] = 0;
        }

        kunmap_atomic(dbuf);

checked:
        afs_stat_v(dvnode, n_read_dir);
        return true;

error:
        return false;
}

/*
 * Dump the contents of a directory.
 */
static void afs_dir_dump(struct afs_vnode *dvnode, struct afs_read *req)
{
        struct afs_xdr_dir_page *dbuf;
        struct address_space *mapping = dvnode->vfs_inode.i_mapping;
        struct page *page;
        unsigned int i, qty = PAGE_SIZE / sizeof(union afs_xdr_dir_block);
        pgoff_t last = req->nr_pages - 1;

        XA_STATE(xas, &mapping->i_pages, 0);

        pr_warn("DIR %llx:%llx f=%llx l=%llx al=%llx\n",
                dvnode->fid.vid, dvnode->fid.vnode,
                req->file_size, req->len, req->actual_len);
        pr_warn("DIR %llx %x %zx %zx\n",
                req->pos, req->nr_pages,
                req->iter->iov_offset,  iov_iter_count(req->iter));

        xas_for_each(&xas, page, last) {
                if (xas_retry(&xas, page))
                        continue;

                BUG_ON(PageCompound(page));
                BUG_ON(page->mapping != mapping);

                dbuf = kmap_atomic(page);
                for (i = 0; i < qty; i++) {
                        union afs_xdr_dir_block *block = &dbuf->blocks[i];

                        pr_warn("[%02lx] %32phN\n", page->index * qty + i, block);
                }
                kunmap_atomic(dbuf);
        }
}

/*
 * Check all the pages in a directory.  All the pages are held pinned.
 */
static int afs_dir_check(struct afs_vnode *dvnode, struct afs_read *req)
{
        struct address_space *mapping = dvnode->vfs_inode.i_mapping;
        struct page *page;
        pgoff_t last = req->nr_pages - 1;
        int ret = 0;

        XA_STATE(xas, &mapping->i_pages, 0);

        if (unlikely(!req->nr_pages))
                return 0;

        rcu_read_lock();
        xas_for_each(&xas, page, last) {
                if (xas_retry(&xas, page))
                        continue;

                BUG_ON(PageCompound(page));
                BUG_ON(page->mapping != mapping);

                if (!afs_dir_check_page(dvnode, page, req->file_size)) {
                        afs_dir_dump(dvnode, req);
                        ret = -EIO;
                        break;
                }
        }

        rcu_read_unlock();
        return ret;
}

/*
 * 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 the directory into the pagecache in one go, scrubbing the previous
 * contents.  The list of pages is returned, pinning them so that they don't
 * get reclaimed during the iteration.
 */
static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
        __acquires(&dvnode->validate_lock)
{
        struct afs_read *req;
        loff_t i_size;
        int nr_pages, i, n;
        int ret;

        _enter("");

        req = kzalloc(sizeof(*req), GFP_KERNEL);
        if (!req)
                return ERR_PTR(-ENOMEM);

        refcount_set(&req->usage, 1);
        req->vnode = dvnode;
        req->key = key_get(key);
        req->cleanup = afs_dir_read_cleanup;

expand:
        i_size = i_size_read(&dvnode->vfs_inode);
        if (i_size < 2048) {
                ret = afs_bad(dvnode, afs_file_error_dir_small);
                goto error;
        }
        if (i_size > 2048 * 1024) {
                trace_afs_file_error(dvnode, -EFBIG, afs_file_error_dir_big);
                ret = -EFBIG;
                goto error;
        }

        _enter("%llu", i_size);

        nr_pages = (i_size + PAGE_SIZE - 1) / PAGE_SIZE;

        req->actual_len = i_size; /* May change */
        req->len = nr_pages * PAGE_SIZE; /* We can ask for more than there is */
        req->data_version = dvnode->status.data_version; /* May change */
        iov_iter_xarray(&req->def_iter, READ, &dvnode->vfs_inode.i_mapping->i_pages,
                        0, i_size);
        req->iter = &req->def_iter;

        /* Fill in any gaps that we might find where the memory reclaimer has
         * been at work and pin all the pages.  If there are any gaps, we will
         * need to reread the entire directory contents.
         */
        i = req->nr_pages;
        while (i < nr_pages) {
                struct page *pages[8], *page;

                n = find_get_pages_contig(dvnode->vfs_inode.i_mapping, i,
                                          min_t(unsigned int, nr_pages - i,
                                                ARRAY_SIZE(pages)),
                                          pages);
                _debug("find %u at %u/%u", n, i, nr_pages);

                if (n == 0) {
                        gfp_t gfp = dvnode->vfs_inode.i_mapping->gfp_mask;

                        if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
                                afs_stat_v(dvnode, n_inval);

                        ret = -ENOMEM;
                        page = __page_cache_alloc(gfp);
                        if (!page)
                                goto error;
                        ret = add_to_page_cache_lru(page,
                                                    dvnode->vfs_inode.i_mapping,
                                                    i, gfp);
                        if (ret < 0)
                                goto error;

                        attach_page_private(page, (void *)1);
                        unlock_page(page);
                        req->nr_pages++;
                        i++;
                } else {
                        req->nr_pages += n;
                        i += n;
                }
        }

        /* If we're going to reload, we need to lock all the pages to prevent
         * races.
         */
        ret = -ERESTARTSYS;
        if (down_read_killable(&dvnode->validate_lock) < 0)
                goto error;

        if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
                goto success;

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

        if (!test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags)) {
                trace_afs_reload_dir(dvnode);
                ret = afs_fetch_data(dvnode, req);
                if (ret < 0)
                        goto error_unlock;

                task_io_account_read(PAGE_SIZE * req->nr_pages);

                if (req->len < req->file_size) {
                        /* The content has grown, so we need to expand the
                         * buffer.
                         */
                        up_write(&dvnode->validate_lock);
                        goto expand;
                }

                /* Validate the data we just read. */
                ret = afs_dir_check(dvnode, req);
                if (ret < 0)
                        goto error_unlock;

                // TODO: Trim excess pages

                set_bit(AFS_VNODE_DIR_VALID, &dvnode->flags);
        }

        downgrade_write(&dvnode->validate_lock);
success:
        return req;

error_unlock:
        up_write(&dvnode->validate_lock);
error:
        afs_put_read(req);
        _leave(" = %d", ret);
        return ERR_PTR(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,
                                 unsigned blkoff)
{
        union afs_xdr_dirent *dire;
        unsigned offset, next, curr, nr_slots;
        size_t nlen;
        int tmp;

        _enter("%u,%x,%p,,",(unsigned)ctx->pos,blkoff,block);

        curr = (ctx->pos - blkoff) / sizeof(union afs_xdr_dirent);

        /* walk through the block, an entry at a time */
        for (offset = (blkoff == 0 ? AFS_DIR_RESV_BLOCKS0 : AFS_DIR_RESV_BLOCKS);
             offset < AFS_DIR_SLOTS_PER_BLOCK;
             offset = next
             ) {
                /* skip entries marked unused in the bitmap */
                if (!(block->hdr.bitmap[offset / 8] &
                      (1 << (offset % 8)))) {
                        _debug("ENT[%zu.%u]: unused",
                               blkoff / sizeof(union afs_xdr_dir_block), offset);
                        next = offset + 1;
                        if (offset >= curr)
                                ctx->pos = blkoff +
                                        next * sizeof(union afs_xdr_dirent);
                        continue;
                }

                /* got a valid entry */
                dire = &block->dirents[offset];
                nlen = strnlen(dire->u.name,
                               sizeof(*block) -
                               offset * sizeof(union afs_xdr_dirent));
                if (nlen > AFSNAMEMAX - 1) {
                        _debug("ENT[%zu]: name too long (len %u/%zu)",
                               blkoff / sizeof(union afs_xdr_dir_block),
                               offset, nlen);
                        return afs_bad(dvnode, afs_file_error_dir_name_too_long);
                }

                _debug("ENT[%zu.%u]: %s %zu \"%s\"",
                       blkoff / sizeof(union afs_xdr_dir_block), offset,
                       (offset < curr ? "skip" : "fill"),
                       nlen, dire->u.name);

                nr_slots = afs_dir_calc_slots(nlen);
                next = offset + nr_slots;
                if (next > AFS_DIR_SLOTS_PER_BLOCK) {
                        _debug("ENT[%zu.%u]:"
                               " %u extends beyond end dir block"
                               " (len %zu)",
                               blkoff / sizeof(union afs_xdr_dir_block),
                               offset, next, 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 ix = offset + tmp;
                        if (!(block->hdr.bitmap[ix / 8] & (1 << (ix % 8)))) {
                                _debug("ENT[%zu.u]:"
                                       " %u unmarked extension (%u/%u)",
                                       blkoff / sizeof(union afs_xdr_dir_block),
                                       offset, tmp, nr_slots);
                                return afs_bad(dvnode, afs_file_error_dir_unmarked_ext);
                        }
                }

                /* skip if starts before the current position */
                if (offset < curr)
                        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 = blkoff + next * sizeof(union afs_xdr_dirent);
        }

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

/*
 * 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 key *key, afs_dataversion_t *_dir_version)
{
        struct afs_vnode *dvnode = AFS_FS_I(dir);
        struct afs_xdr_dir_page *dbuf;
        union afs_xdr_dir_block *dblock;
        struct afs_read *req;
        struct page *page;
        unsigned blkoff, limit;
        void __rcu **slot;
        int ret;

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

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

        req = afs_read_dir(dvnode, key);
        if (IS_ERR(req))
                return PTR_ERR(req);
        *_dir_version = req->data_version;

        /* round the file position up to the next entry boundary */
        ctx->pos += sizeof(union afs_xdr_dirent) - 1;
        ctx->pos &= ~(sizeof(union afs_xdr_dirent) - 1);

        /* walk through the blocks in sequence */
        ret = 0;
        while (ctx->pos < req->actual_len) {
                blkoff = ctx->pos & ~(sizeof(union afs_xdr_dir_block) - 1);

                /* Fetch the appropriate page from the directory and re-add it
                 * to the LRU.  We have all the pages pinned with an extra ref.
                 */
                rcu_read_lock();
                page = NULL;
                slot = radix_tree_lookup_slot(&dvnode->vfs_inode.i_mapping->i_pages,
                                              blkoff / PAGE_SIZE);
                if (slot)
                        page = radix_tree_deref_slot(slot);
                rcu_read_unlock();
                if (!page) {
                        ret = afs_bad(dvnode, afs_file_error_dir_missing_page);
                        break;
                }
                mark_page_accessed(page);

                limit = blkoff & ~(PAGE_SIZE - 1);

                dbuf = kmap(page);

                /* deal with the individual blocks stashed on this page */
                do {
                        dblock = &dbuf->blocks[(blkoff % PAGE_SIZE) /
                                               sizeof(union afs_xdr_dir_block)];
                        ret = afs_dir_iterate_block(dvnode, ctx, dblock, blkoff);
                        if (ret != 1) {
                                kunmap(page);
                                goto out;
                        }

                        blkoff += sizeof(union afs_xdr_dir_block);

                } while (ctx->pos < dir->i_size && blkoff < limit);

                kunmap(page);
                ret = 0;
        }

out:
        up_read(&dvnode->validate_lock);
        afs_put_read(req);
        _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, afs_file_key(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 int 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(" = 0 [no]");
                return 0;
        }

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

        _leave(" = -1 [found]");
        return -1;
}

/*
 * 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, struct dentry *dentry,
                             struct afs_fid *fid, struct key *key,
                             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 = dentry->d_name,
                .fid.vid = as->volume->vid
        };
        int ret;

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

        /* search the directory */
        ret = afs_dir_iterate(dir, &cookie.ctx, key, _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 int 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);
        int ret;

        _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->found) {
                if (cookie->nr_fids < 50) {
                        cookie->fids[cookie->nr_fids].vnode     = ino;
                        cookie->fids[cookie->nr_fids].unique    = dtype;
                        cookie->nr_fids++;
                }
        } else if (cookie->name.len == nlen &&
                   memcmp(cookie->name.name, name, nlen) == 0) {
                cookie->fids[1].vnode   = ino;
                cookie->fids[1].unique  = dtype;
                cookie->found = 1;
                if (cookie->one_only)
                        return -1;
        }

        ret = cookie->nr_fids >= 50 ? -1 : 0;
        _leave(" = %d", ret);
        return ret;
}

/*
 * 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->ac.abort_code = abort_code;
                                op->error = afs_abort_to_error(abort_code);
                        }
                        break;

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

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

                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 key *key)
{
        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);
        long ret;
        int i;

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

        cookie = kzalloc(sizeof(struct afs_lookup_cookie), GFP_KERNEL);
        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 0 is saved for the fid we actually want
                              * and slot 1 for the directory */

        if (!afs_server_supports_ibulk(dvnode))
                cookie->one_only = true;

        /* search the directory */
        ret = afs_dir_iterate(dir, &cookie->ctx, key, &data_version);
        if (ret < 0)
                goto out;

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

        ret = -ENOENT;
        if (!cookie->found)
                goto out;

        /* 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 */
        op->error = -ENOMEM;
        if (op->nr_files > 2) {
                op->more_files = kvcalloc(op->nr_files - 2,
                                          sizeof(struct afs_vnode_param),
                                          GFP_KERNEL);
                if (!op->more_files)
                        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);
                        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.
         */
        op->error = -ENOTSUPP;
        if (!cookie->one_only) {
                op->ops = &afs_inline_bulk_status_operation;
                afs_begin_vnode_operation(op);
                afs_wait_for_operation(op);
        }

        if (op->error == -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);
        }
        inode = ERR_PTR(op->error);

out_op:
        if (op->error == 0) {
                inode = &op->file[1].vnode->vfs_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 key *key)
{
        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_one_len(buf, dentry->d_parent, len);
                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:
        key_put(key);
        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;
        struct key *key;
        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);
        }

        key = afs_request_key(dvnode->volume->cell);
        if (IS_ERR(key)) {
                _leave(" = %ld [key]", PTR_ERR(key));
                return ERR_CAST(key);
        }

        ret = afs_validate(dvnode, key);
        if (ret < 0) {
                key_put(key);
                _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, key);

        afs_stat_v(dvnode, n_lookup);
        inode = afs_do_lookup(dir, dentry, key);
        key_put(key);
        if (inode == ERR_PTR(-ENOENT))
                inode = afs_try_auto_mntpt(dentry, dir);

        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 dentry *dentry)
{
        struct afs_vnode *dvnode;
        struct dentry *parent;
        struct inode *dir;
        long dir_version, de_version;

        _enter("%p", dentry);

        /* Check the parent directory is still valid first. */
        parent = READ_ONCE(dentry->d_parent);
        dir = d_inode_rcu(parent);
        if (!dir)
                return -ECHILD;
        dvnode = AFS_FS_I(dir);
        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 dentry *dentry, unsigned int flags)
{
        struct afs_vnode *vnode, *dir;
        struct afs_fid fid;
        struct dentry *parent;
        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(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;

        /* Hold the parent dentry so we can peer at it */
        parent = dget_parent(dentry);
        dir = AFS_FS_I(d_inode(parent));

        /* validate the parent directory */
        afs_validate(dir, key);

        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->vfs_inode, dentry, &fid, key, &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->vfs_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 dir %pd: %d",
                       parent, ret);
                goto not_found;
        }

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

not_found:
        _debug("dropping dentry %pd2", dentry);
        dput(parent);
        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 (op->ac.abort_code) {
        case VNOVNODE:
                set_bit(AFS_VNODE_DELETED, &vnode->flags);
                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 *vp = &op->file[1];
        struct afs_vnode *vnode;
        struct inode *inode;

        _enter("");

        ASSERTCMP(op->error, ==, 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.
                 */
                op->error = PTR_ERR(inode);
                return;
        }

        vnode = AFS_FS_I(inode);
        set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
        if (!op->error)
                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 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);

        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);
}

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

        if (op->error)
                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 int afs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
                     struct dentry *dentry, umode_t mode)
{
        struct afs_operation *op;
        struct afs_vnode *dvnode = AFS_FS_I(dir);

        _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 PTR_ERR(op);
        }

        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->ops         = &afs_mkdir_operation;
        return afs_do_sync_operation(op);
}

/*
 * 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->vfs_inode);
                set_bit(AFS_VNODE_DELETED, &vnode->flags);
                clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
                clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
        }
}

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 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);

        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);
}

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);

        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;
        }

        return afs_do_sync_operation(op);

error:
        return afs_put_operation(op);
}

/*
 * 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 (op->error != 0 ||
            (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->vfs_inode);
                if (vnode->vfs_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)
                        op->error = ret;
        }

        _debug("nlink %d [val %d]", vnode->vfs_inode.i_nlink, op->error);
}

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 afs_vnode_param *dvp = &op->file[0];
        struct afs_vnode *dvnode = dvp->vnode;

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

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

        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) {
                op->error = 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);
                op->error = 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 (op->error == 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);
        }

        return afs_put_operation(op);

error:
        return afs_put_operation(op);
}

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 user_namespace *mnt_userns, 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;
        }

        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->ops         = &afs_create_operation;
        return afs_do_sync_operation(op);

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->vfs_inode);
        d_instantiate(op->dentry, &vp->vnode->vfs_inode);
}

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

        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;
        return afs_do_sync_operation(op);

error_op:
        afs_put_operation(op);
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 user_namespace *mnt_userns, 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;
        }

        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;
        return afs_do_sync_operation(op);

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

static void afs_rename_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[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]);
        }
}

static void afs_rename_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 *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;
        }

        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);
        }

        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.
         *
         * Note that if we ever implement RENAME_EXCHANGE, we'll have
         * to update both dentries with opposing dir versions.
         */
        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);
}

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 (op->error)
                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,
};

/*
 * rename a file in an AFS filesystem and/or move it between directories
 */
static int afs_rename(struct user_namespace *mnt_userns, 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;
        int ret;

        if (flags)
                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);

        _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);

        ret = afs_validate(vnode, op->key);
        op->error = ret;
        if (ret < 0)
                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->dentry              = old_dentry;
        op->dentry_2            = new_dentry;
        op->rename.new_negative = d_is_negative(new_dentry);
        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) {
                                op->error = -ENOMEM;
                                goto error;
                        }

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

        return afs_do_sync_operation(op);

error:
        return afs_put_operation(op);
}

/*
 * Release a directory page and clean up its private state if it's not busy
 * - return true if the page can now be released, false if not
 */
static int afs_dir_releasepage(struct page *page, gfp_t gfp_flags)
{
        struct afs_vnode *dvnode = AFS_FS_I(page->mapping->host);

        _enter("{{%llx:%llu}[%lu]}", dvnode->fid.vid, dvnode->fid.vnode, page->index);

        detach_page_private(page);

        /* The directory will need reloading. */
        if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
                afs_stat_v(dvnode, n_relpg);
        return 1;
}

/*
 * invalidate part or all of a page
 * - release a page and clean up its private data if offset is 0 (indicating
 *   the entire page)
 */
static void afs_dir_invalidatepage(struct page *page, unsigned int offset,
                                   unsigned int length)
{
        struct afs_vnode *dvnode = AFS_FS_I(page->mapping->host);

        _enter("{%lu},%u,%u", page->index, offset, length);

        BUG_ON(!PageLocked(page));

        /* The directory will need reloading. */
        if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
                afs_stat_v(dvnode, n_inval);

        /* we clean up only if the entire page is being invalidated */
        if (offset == 0 && length == thp_size(page))
                detach_page_private(page);
}