// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>
#include <linux/ceph/striper.h>

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/writeback.h>
#include <linux/falloc.h>
#include <linux/iversion.h>
#include <linux/ktime.h>

#include "super.h"
#include "mds_client.h"
#include "cache.h"
#include "io.h"
#include "metric.h"

static __le32 ceph_flags_sys2wire(u32 flags)
{
        u32 wire_flags = 0;

        switch (flags & O_ACCMODE) {
        case O_RDONLY:
                wire_flags |= CEPH_O_RDONLY;
                break;
        case O_WRONLY:
                wire_flags |= CEPH_O_WRONLY;
                break;
        case O_RDWR:
                wire_flags |= CEPH_O_RDWR;
                break;
        }

        flags &= ~O_ACCMODE;

#define ceph_sys2wire(a) if (flags & a) { wire_flags |= CEPH_##a; flags &= ~a; }

        ceph_sys2wire(O_CREAT);
        ceph_sys2wire(O_EXCL);
        ceph_sys2wire(O_TRUNC);
        ceph_sys2wire(O_DIRECTORY);
        ceph_sys2wire(O_NOFOLLOW);

#undef ceph_sys2wire

        if (flags)
                dout("unused open flags: %x\n", flags);

        return cpu_to_le32(wire_flags);
}

/*
 * Ceph file operations
 *
 * Implement basic open/close functionality, and implement
 * read/write.
 *
 * We implement three modes of file I/O:
 *  - buffered uses the generic_file_aio_{read,write} helpers
 *
 *  - synchronous is used when there is multi-client read/write
 *    sharing, avoids the page cache, and synchronously waits for an
 *    ack from the OSD.
 *
 *  - direct io takes the variant of the sync path that references
 *    user pages directly.
 *
 * fsync() flushes and waits on dirty pages, but just queues metadata
 * for writeback: since the MDS can recover size and mtime there is no
 * need to wait for MDS acknowledgement.
 */

/*
 * How many pages to get in one call to iov_iter_get_pages().  This
 * determines the size of the on-stack array used as a buffer.
 */
#define ITER_GET_BVECS_PAGES    64

static ssize_t __iter_get_bvecs(struct iov_iter *iter, size_t maxsize,
                                struct bio_vec *bvecs)
{
        size_t size = 0;
        int bvec_idx = 0;

        if (maxsize > iov_iter_count(iter))
                maxsize = iov_iter_count(iter);

        while (size < maxsize) {
                struct page *pages[ITER_GET_BVECS_PAGES];
                ssize_t bytes;
                size_t start;
                int idx = 0;

                bytes = iov_iter_get_pages(iter, pages, maxsize - size,
                                           ITER_GET_BVECS_PAGES, &start);
                if (bytes < 0)
                        return size ?: bytes;

                iov_iter_advance(iter, bytes);
                size += bytes;

                for ( ; bytes; idx++, bvec_idx++) {
                        struct bio_vec bv = {
                                .bv_page = pages[idx],
                                .bv_len = min_t(int, bytes, PAGE_SIZE - start),
                                .bv_offset = start,
                        };

                        bvecs[bvec_idx] = bv;
                        bytes -= bv.bv_len;
                        start = 0;
                }
        }

        return size;
}

/*
 * iov_iter_get_pages() only considers one iov_iter segment, no matter
 * what maxsize or maxpages are given.  For ITER_BVEC that is a single
 * page.
 *
 * Attempt to get up to @maxsize bytes worth of pages from @iter.
 * Return the number of bytes in the created bio_vec array, or an error.
 */
static ssize_t iter_get_bvecs_alloc(struct iov_iter *iter, size_t maxsize,
                                    struct bio_vec **bvecs, int *num_bvecs)
{
        struct bio_vec *bv;
        size_t orig_count = iov_iter_count(iter);
        ssize_t bytes;
        int npages;

        iov_iter_truncate(iter, maxsize);
        npages = iov_iter_npages(iter, INT_MAX);
        iov_iter_reexpand(iter, orig_count);

        /*
         * __iter_get_bvecs() may populate only part of the array -- zero it
         * out.
         */
        bv = kvmalloc_array(npages, sizeof(*bv), GFP_KERNEL | __GFP_ZERO);
        if (!bv)
                return -ENOMEM;

        bytes = __iter_get_bvecs(iter, maxsize, bv);
        if (bytes < 0) {
                /*
                 * No pages were pinned -- just free the array.
                 */
                kvfree(bv);
                return bytes;
        }

        *bvecs = bv;
        *num_bvecs = npages;
        return bytes;
}

static void put_bvecs(struct bio_vec *bvecs, int num_bvecs, bool should_dirty)
{
        int i;

        for (i = 0; i < num_bvecs; i++) {
                if (bvecs[i].bv_page) {
                        if (should_dirty)
                                set_page_dirty_lock(bvecs[i].bv_page);
                        put_page(bvecs[i].bv_page);
                }
        }
        kvfree(bvecs);
}

/*
 * Prepare an open request.  Preallocate ceph_cap to avoid an
 * inopportune ENOMEM later.
 */
static struct ceph_mds_request *
prepare_open_request(struct super_block *sb, int flags, int create_mode)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(sb);
        struct ceph_mds_request *req;
        int want_auth = USE_ANY_MDS;
        int op = (flags & O_CREAT) ? CEPH_MDS_OP_CREATE : CEPH_MDS_OP_OPEN;

        if (flags & (O_WRONLY|O_RDWR|O_CREAT|O_TRUNC))
                want_auth = USE_AUTH_MDS;

        req = ceph_mdsc_create_request(mdsc, op, want_auth);
        if (IS_ERR(req))
                goto out;
        req->r_fmode = ceph_flags_to_mode(flags);
        req->r_args.open.flags = ceph_flags_sys2wire(flags);
        req->r_args.open.mode = cpu_to_le32(create_mode);
out:
        return req;
}

static int ceph_init_file_info(struct inode *inode, struct file *file,
                                        int fmode, bool isdir)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_file_info *fi;

        dout("%s %p %p 0%o (%s)\n", __func__, inode, file,
                        inode->i_mode, isdir ? "dir" : "regular");
        BUG_ON(inode->i_fop->release != ceph_release);

        if (isdir) {
                struct ceph_dir_file_info *dfi =
                        kmem_cache_zalloc(ceph_dir_file_cachep, GFP_KERNEL);
                if (!dfi)
                        return -ENOMEM;

                file->private_data = dfi;
                fi = &dfi->file_info;
                dfi->next_offset = 2;
                dfi->readdir_cache_idx = -1;
        } else {
                fi = kmem_cache_zalloc(ceph_file_cachep, GFP_KERNEL);
                if (!fi)
                        return -ENOMEM;

                file->private_data = fi;
        }

        ceph_get_fmode(ci, fmode, 1);
        fi->fmode = fmode;

        spin_lock_init(&fi->rw_contexts_lock);
        INIT_LIST_HEAD(&fi->rw_contexts);
        fi->meta_err = errseq_sample(&ci->i_meta_err);
        fi->filp_gen = READ_ONCE(ceph_inode_to_client(inode)->filp_gen);

        return 0;
}

/*
 * initialize private struct file data.
 * if we fail, clean up by dropping fmode reference on the ceph_inode
 */
static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
{
        int ret = 0;

        switch (inode->i_mode & S_IFMT) {
        case S_IFREG:
                ceph_fscache_register_inode_cookie(inode);
                ceph_fscache_file_set_cookie(inode, file);
                fallthrough;
        case S_IFDIR:
                ret = ceph_init_file_info(inode, file, fmode,
                                                S_ISDIR(inode->i_mode));
                break;

        case S_IFLNK:
                dout("init_file %p %p 0%o (symlink)\n", inode, file,
                     inode->i_mode);
                break;

        default:
                dout("init_file %p %p 0%o (special)\n", inode, file,
                     inode->i_mode);
                /*
                 * we need to drop the open ref now, since we don't
                 * have .release set to ceph_release.
                 */
                BUG_ON(inode->i_fop->release == ceph_release);

                /* call the proper open fop */
                ret = inode->i_fop->open(inode, file);
        }
        return ret;
}

/*
 * try renew caps after session gets killed.
 */
int ceph_renew_caps(struct inode *inode, int fmode)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_mds_request *req;
        int err, flags, wanted;

        spin_lock(&ci->i_ceph_lock);
        __ceph_touch_fmode(ci, mdsc, fmode);
        wanted = __ceph_caps_file_wanted(ci);
        if (__ceph_is_any_real_caps(ci) &&
            (!(wanted & CEPH_CAP_ANY_WR) || ci->i_auth_cap)) {
                int issued = __ceph_caps_issued(ci, NULL);
                spin_unlock(&ci->i_ceph_lock);
                dout("renew caps %p want %s issued %s updating mds_wanted\n",
                     inode, ceph_cap_string(wanted), ceph_cap_string(issued));
                ceph_check_caps(ci, 0, NULL);
                return 0;
        }
        spin_unlock(&ci->i_ceph_lock);

        flags = 0;
        if ((wanted & CEPH_CAP_FILE_RD) && (wanted & CEPH_CAP_FILE_WR))
                flags = O_RDWR;
        else if (wanted & CEPH_CAP_FILE_RD)
                flags = O_RDONLY;
        else if (wanted & CEPH_CAP_FILE_WR)
                flags = O_WRONLY;
#ifdef O_LAZY
        if (wanted & CEPH_CAP_FILE_LAZYIO)
                flags |= O_LAZY;
#endif

        req = prepare_open_request(inode->i_sb, flags, 0);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto out;
        }

        req->r_inode = inode;
        ihold(inode);
        req->r_num_caps = 1;

        err = ceph_mdsc_do_request(mdsc, NULL, req);
        ceph_mdsc_put_request(req);
out:
        dout("renew caps %p open result=%d\n", inode, err);
        return err < 0 ? err : 0;
}

/*
 * If we already have the requisite capabilities, we can satisfy
 * the open request locally (no need to request new caps from the
 * MDS).  We do, however, need to inform the MDS (asynchronously)
 * if our wanted caps set expands.
 */
int ceph_open(struct inode *inode, struct file *file)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
        struct ceph_mds_client *mdsc = fsc->mdsc;
        struct ceph_mds_request *req;
        struct ceph_file_info *fi = file->private_data;
        int err;
        int flags, fmode, wanted;

        if (fi) {
                dout("open file %p is already opened\n", file);
                return 0;
        }

        /* filter out O_CREAT|O_EXCL; vfs did that already.  yuck. */
        flags = file->f_flags & ~(O_CREAT|O_EXCL);
        if (S_ISDIR(inode->i_mode))
                flags = O_DIRECTORY;  /* mds likes to know */

        dout("open inode %p ino %llx.%llx file %p flags %d (%d)\n", inode,
             ceph_vinop(inode), file, flags, file->f_flags);
        fmode = ceph_flags_to_mode(flags);
        wanted = ceph_caps_for_mode(fmode);

        /* snapped files are read-only */
        if (ceph_snap(inode) != CEPH_NOSNAP && (file->f_mode & FMODE_WRITE))
                return -EROFS;

        /* trivially open snapdir */
        if (ceph_snap(inode) == CEPH_SNAPDIR) {
                return ceph_init_file(inode, file, fmode);
        }

        /*
         * No need to block if we have caps on the auth MDS (for
         * write) or any MDS (for read).  Update wanted set
         * asynchronously.
         */
        spin_lock(&ci->i_ceph_lock);
        if (__ceph_is_any_real_caps(ci) &&
            (((fmode & CEPH_FILE_MODE_WR) == 0) || ci->i_auth_cap)) {
                int mds_wanted = __ceph_caps_mds_wanted(ci, true);
                int issued = __ceph_caps_issued(ci, NULL);

                dout("open %p fmode %d want %s issued %s using existing\n",
                     inode, fmode, ceph_cap_string(wanted),
                     ceph_cap_string(issued));
                __ceph_touch_fmode(ci, mdsc, fmode);
                spin_unlock(&ci->i_ceph_lock);

                /* adjust wanted? */
                if ((issued & wanted) != wanted &&
                    (mds_wanted & wanted) != wanted &&
                    ceph_snap(inode) != CEPH_SNAPDIR)
                        ceph_check_caps(ci, 0, NULL);

                return ceph_init_file(inode, file, fmode);
        } else if (ceph_snap(inode) != CEPH_NOSNAP &&
                   (ci->i_snap_caps & wanted) == wanted) {
                __ceph_touch_fmode(ci, mdsc, fmode);
                spin_unlock(&ci->i_ceph_lock);
                return ceph_init_file(inode, file, fmode);
        }

        spin_unlock(&ci->i_ceph_lock);

        dout("open fmode %d wants %s\n", fmode, ceph_cap_string(wanted));
        req = prepare_open_request(inode->i_sb, flags, 0);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto out;
        }
        req->r_inode = inode;
        ihold(inode);

        req->r_num_caps = 1;
        err = ceph_mdsc_do_request(mdsc, NULL, req);
        if (!err)
                err = ceph_init_file(inode, file, req->r_fmode);
        ceph_mdsc_put_request(req);
        dout("open result=%d on %llx.%llx\n", err, ceph_vinop(inode));
out:
        return err;
}

/* Clone the layout from a synchronous create, if the dir now has Dc caps */
static void
cache_file_layout(struct inode *dst, struct inode *src)
{
        struct ceph_inode_info *cdst = ceph_inode(dst);
        struct ceph_inode_info *csrc = ceph_inode(src);

        spin_lock(&cdst->i_ceph_lock);
        if ((__ceph_caps_issued(cdst, NULL) & CEPH_CAP_DIR_CREATE) &&
            !ceph_file_layout_is_valid(&cdst->i_cached_layout)) {
                memcpy(&cdst->i_cached_layout, &csrc->i_layout,
                        sizeof(cdst->i_cached_layout));
                rcu_assign_pointer(cdst->i_cached_layout.pool_ns,
                                   ceph_try_get_string(csrc->i_layout.pool_ns));
        }
        spin_unlock(&cdst->i_ceph_lock);
}

/*
 * Try to set up an async create. We need caps, a file layout, and inode number,
 * and either a lease on the dentry or complete dir info. If any of those
 * criteria are not satisfied, then return false and the caller can go
 * synchronous.
 */
static int try_prep_async_create(struct inode *dir, struct dentry *dentry,
                                 struct ceph_file_layout *lo, u64 *pino)
{
        struct ceph_inode_info *ci = ceph_inode(dir);
        struct ceph_dentry_info *di = ceph_dentry(dentry);
        int got = 0, want = CEPH_CAP_FILE_EXCL | CEPH_CAP_DIR_CREATE;
        u64 ino;

        spin_lock(&ci->i_ceph_lock);
        /* No auth cap means no chance for Dc caps */
        if (!ci->i_auth_cap)
                goto no_async;

        /* Any delegated inos? */
        if (xa_empty(&ci->i_auth_cap->session->s_delegated_inos))
                goto no_async;

        if (!ceph_file_layout_is_valid(&ci->i_cached_layout))
                goto no_async;

        if ((__ceph_caps_issued(ci, NULL) & want) != want)
                goto no_async;

        if (d_in_lookup(dentry)) {
                if (!__ceph_dir_is_complete(ci))
                        goto no_async;
                spin_lock(&dentry->d_lock);
                di->lease_shared_gen = atomic_read(&ci->i_shared_gen);
                spin_unlock(&dentry->d_lock);
        } else if (atomic_read(&ci->i_shared_gen) !=
                   READ_ONCE(di->lease_shared_gen)) {
                goto no_async;
        }

        ino = ceph_get_deleg_ino(ci->i_auth_cap->session);
        if (!ino)
                goto no_async;

        *pino = ino;
        ceph_take_cap_refs(ci, want, false);
        memcpy(lo, &ci->i_cached_layout, sizeof(*lo));
        rcu_assign_pointer(lo->pool_ns,
                           ceph_try_get_string(ci->i_cached_layout.pool_ns));
        got = want;
no_async:
        spin_unlock(&ci->i_ceph_lock);
        return got;
}

static void restore_deleg_ino(struct inode *dir, u64 ino)
{
        struct ceph_inode_info *ci = ceph_inode(dir);
        struct ceph_mds_session *s = NULL;

        spin_lock(&ci->i_ceph_lock);
        if (ci->i_auth_cap)
                s = ceph_get_mds_session(ci->i_auth_cap->session);
        spin_unlock(&ci->i_ceph_lock);
        if (s) {
                int err = ceph_restore_deleg_ino(s, ino);
                if (err)
                        pr_warn("ceph: unable to restore delegated ino 0x%llx to session: %d\n",
                                ino, err);
                ceph_put_mds_session(s);
        }
}

static void ceph_async_create_cb(struct ceph_mds_client *mdsc,
                                 struct ceph_mds_request *req)
{
        int result = req->r_err ? req->r_err :
                        le32_to_cpu(req->r_reply_info.head->result);

        if (result == -EJUKEBOX)
                goto out;

        mapping_set_error(req->r_parent->i_mapping, result);

        if (result) {
                struct dentry *dentry = req->r_dentry;
                int pathlen = 0;
                u64 base = 0;
                char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
                                                  &base, 0);

                ceph_dir_clear_complete(req->r_parent);
                if (!d_unhashed(dentry))
                        d_drop(dentry);

                /* FIXME: start returning I/O errors on all accesses? */
                pr_warn("ceph: async create failure path=(%llx)%s result=%d!\n",
                        base, IS_ERR(path) ? "<<bad>>" : path, result);
                ceph_mdsc_free_path(path, pathlen);
        }

        if (req->r_target_inode) {
                struct ceph_inode_info *ci = ceph_inode(req->r_target_inode);
                u64 ino = ceph_vino(req->r_target_inode).ino;

                if (req->r_deleg_ino != ino)
                        pr_warn("%s: inode number mismatch! err=%d deleg_ino=0x%llx target=0x%llx\n",
                                __func__, req->r_err, req->r_deleg_ino, ino);
                mapping_set_error(req->r_target_inode->i_mapping, result);

                spin_lock(&ci->i_ceph_lock);
                if (ci->i_ceph_flags & CEPH_I_ASYNC_CREATE) {
                        ci->i_ceph_flags &= ~CEPH_I_ASYNC_CREATE;
                        wake_up_bit(&ci->i_ceph_flags, CEPH_ASYNC_CREATE_BIT);
                }
                ceph_kick_flushing_inode_caps(req->r_session, ci);
                spin_unlock(&ci->i_ceph_lock);
        } else {
                pr_warn("%s: no req->r_target_inode for 0x%llx\n", __func__,
                        req->r_deleg_ino);
        }
out:
        ceph_mdsc_release_dir_caps(req);
}

static int ceph_finish_async_create(struct inode *dir, struct dentry *dentry,
                                    struct file *file, umode_t mode,
                                    struct ceph_mds_request *req,
                                    struct ceph_acl_sec_ctx *as_ctx,
                                    struct ceph_file_layout *lo)
{
        int ret;
        char xattr_buf[4];
        struct ceph_mds_reply_inode in = { };
        struct ceph_mds_reply_info_in iinfo = { .in = &in };
        struct ceph_inode_info *ci = ceph_inode(dir);
        struct inode *inode;
        struct timespec64 now;
        struct ceph_vino vino = { .ino = req->r_deleg_ino,
                                  .snap = CEPH_NOSNAP };

        ktime_get_real_ts64(&now);

        inode = ceph_get_inode(dentry->d_sb, vino);
        if (IS_ERR(inode))
                return PTR_ERR(inode);

        iinfo.inline_version = CEPH_INLINE_NONE;
        iinfo.change_attr = 1;
        ceph_encode_timespec64(&iinfo.btime, &now);

        iinfo.xattr_len = ARRAY_SIZE(xattr_buf);
        iinfo.xattr_data = xattr_buf;
        memset(iinfo.xattr_data, 0, iinfo.xattr_len);

        in.ino = cpu_to_le64(vino.ino);
        in.snapid = cpu_to_le64(CEPH_NOSNAP);
        in.version = cpu_to_le64(1);    // ???
        in.cap.caps = in.cap.wanted = cpu_to_le32(CEPH_CAP_ALL_FILE);
        in.cap.cap_id = cpu_to_le64(1);
        in.cap.realm = cpu_to_le64(ci->i_snap_realm->ino);
        in.cap.flags = CEPH_CAP_FLAG_AUTH;
        in.ctime = in.mtime = in.atime = iinfo.btime;
        in.mode = cpu_to_le32((u32)mode);
        in.truncate_seq = cpu_to_le32(1);
        in.truncate_size = cpu_to_le64(-1ULL);
        in.xattr_version = cpu_to_le64(1);
        in.uid = cpu_to_le32(from_kuid(&init_user_ns, current_fsuid()));
        in.gid = cpu_to_le32(from_kgid(&init_user_ns, dir->i_mode & S_ISGID ?
                                dir->i_gid : current_fsgid()));
        in.nlink = cpu_to_le32(1);
        in.max_size = cpu_to_le64(lo->stripe_unit);

        ceph_file_layout_to_legacy(lo, &in.layout);

        ret = ceph_fill_inode(inode, NULL, &iinfo, NULL, req->r_session,
                              req->r_fmode, NULL);
        if (ret) {
                dout("%s failed to fill inode: %d\n", __func__, ret);
                ceph_dir_clear_complete(dir);
                if (!d_unhashed(dentry))
                        d_drop(dentry);
                if (inode->i_state & I_NEW)
                        discard_new_inode(inode);
        } else {
                struct dentry *dn;

                dout("%s d_adding new inode 0x%llx to 0x%llx/%s\n", __func__,
                        vino.ino, ceph_ino(dir), dentry->d_name.name);
                ceph_dir_clear_ordered(dir);
                ceph_init_inode_acls(inode, as_ctx);
                if (inode->i_state & I_NEW) {
                        /*
                         * If it's not I_NEW, then someone created this before
                         * we got here. Assume the server is aware of it at
                         * that point and don't worry about setting
                         * CEPH_I_ASYNC_CREATE.
                         */
                        ceph_inode(inode)->i_ceph_flags = CEPH_I_ASYNC_CREATE;
                        unlock_new_inode(inode);
                }
                if (d_in_lookup(dentry) || d_really_is_negative(dentry)) {
                        if (!d_unhashed(dentry))
                                d_drop(dentry);
                        dn = d_splice_alias(inode, dentry);
                        WARN_ON_ONCE(dn && dn != dentry);
                }
                file->f_mode |= FMODE_CREATED;
                ret = finish_open(file, dentry, ceph_open);
        }
        return ret;
}

/*
 * Do a lookup + open with a single request.  If we get a non-existent
 * file or symlink, return 1 so the VFS can retry.
 */
int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
                     struct file *file, unsigned flags, umode_t mode)
{
        struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
        struct ceph_mds_client *mdsc = fsc->mdsc;
        struct ceph_mds_request *req;
        struct dentry *dn;
        struct ceph_acl_sec_ctx as_ctx = {};
        bool try_async = ceph_test_mount_opt(fsc, ASYNC_DIROPS);
        int mask;
        int err;

        dout("atomic_open %p dentry %p '%pd' %s flags %d mode 0%o\n",
             dir, dentry, dentry,
             d_unhashed(dentry) ? "unhashed" : "hashed", flags, mode);

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

        if (flags & O_CREAT) {
                if (ceph_quota_is_max_files_exceeded(dir))
                        return -EDQUOT;
                err = ceph_pre_init_acls(dir, &mode, &as_ctx);
                if (err < 0)
                        return err;
                err = ceph_security_init_secctx(dentry, mode, &as_ctx);
                if (err < 0)
                        goto out_ctx;
        } else if (!d_in_lookup(dentry)) {
                /* If it's not being looked up, it's negative */
                return -ENOENT;
        }
retry:
        /* do the open */
        req = prepare_open_request(dir->i_sb, flags, mode);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto out_ctx;
        }
        req->r_dentry = dget(dentry);
        req->r_num_caps = 2;
        mask = CEPH_STAT_CAP_INODE | CEPH_CAP_AUTH_SHARED;
        if (ceph_security_xattr_wanted(dir))
                mask |= CEPH_CAP_XATTR_SHARED;
        req->r_args.open.mask = cpu_to_le32(mask);
        req->r_parent = dir;

        if (flags & O_CREAT) {
                struct ceph_file_layout lo;

                req->r_dentry_drop = CEPH_CAP_FILE_SHARED | CEPH_CAP_AUTH_EXCL;
                req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
                if (as_ctx.pagelist) {
                        req->r_pagelist = as_ctx.pagelist;
                        as_ctx.pagelist = NULL;
                }
                if (try_async &&
                    (req->r_dir_caps =
                      try_prep_async_create(dir, dentry, &lo,
                                            &req->r_deleg_ino))) {
                        set_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags);
                        req->r_args.open.flags |= cpu_to_le32(CEPH_O_EXCL);
                        req->r_callback = ceph_async_create_cb;
                        err = ceph_mdsc_submit_request(mdsc, dir, req);
                        if (!err) {
                                err = ceph_finish_async_create(dir, dentry,
                                                        file, mode, req,
                                                        &as_ctx, &lo);
                        } else if (err == -EJUKEBOX) {
                                restore_deleg_ino(dir, req->r_deleg_ino);
                                ceph_mdsc_put_request(req);
                                try_async = false;
                                goto retry;
                        }
                        goto out_req;
                }
        }

        set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
        err = ceph_mdsc_do_request(mdsc,
                                   (flags & (O_CREAT|O_TRUNC)) ? dir : NULL,
                                   req);
        err = ceph_handle_snapdir(req, dentry, err);
        if (err)
                goto out_req;

        if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry)
                err = ceph_handle_notrace_create(dir, dentry);

        if (d_in_lookup(dentry)) {
                dn = ceph_finish_lookup(req, dentry, err);
                if (IS_ERR(dn))
                        err = PTR_ERR(dn);
        } else {
                /* we were given a hashed negative dentry */
                dn = NULL;
        }
        if (err)
                goto out_req;
        if (dn || d_really_is_negative(dentry) || d_is_symlink(dentry)) {
                /* make vfs retry on splice, ENOENT, or symlink */
                dout("atomic_open finish_no_open on dn %p\n", dn);
                err = finish_no_open(file, dn);
        } else {
                dout("atomic_open finish_open on dn %p\n", dn);
                if (req->r_op == CEPH_MDS_OP_CREATE && req->r_reply_info.has_create_ino) {
                        struct inode *newino = d_inode(dentry);

                        cache_file_layout(dir, newino);
                        ceph_init_inode_acls(newino, &as_ctx);
                        file->f_mode |= FMODE_CREATED;
                }
                err = finish_open(file, dentry, ceph_open);
        }
out_req:
        ceph_mdsc_put_request(req);
out_ctx:
        ceph_release_acl_sec_ctx(&as_ctx);
        dout("atomic_open result=%d\n", err);
        return err;
}

int ceph_release(struct inode *inode, struct file *file)
{
        struct ceph_inode_info *ci = ceph_inode(inode);

        if (S_ISDIR(inode->i_mode)) {
                struct ceph_dir_file_info *dfi = file->private_data;
                dout("release inode %p dir file %p\n", inode, file);
                WARN_ON(!list_empty(&dfi->file_info.rw_contexts));

                ceph_put_fmode(ci, dfi->file_info.fmode, 1);

                if (dfi->last_readdir)
                        ceph_mdsc_put_request(dfi->last_readdir);
                kfree(dfi->last_name);
                kfree(dfi->dir_info);
                kmem_cache_free(ceph_dir_file_cachep, dfi);
        } else {
                struct ceph_file_info *fi = file->private_data;
                dout("release inode %p regular file %p\n", inode, file);
                WARN_ON(!list_empty(&fi->rw_contexts));

                ceph_put_fmode(ci, fi->fmode, 1);

                kmem_cache_free(ceph_file_cachep, fi);
        }

        /* wake up anyone waiting for caps on this inode */
        wake_up_all(&ci->i_cap_wq);
        return 0;
}

enum {
        HAVE_RETRIED = 1,
        CHECK_EOF =    2,
        READ_INLINE =  3,
};

/*
 * Completely synchronous read and write methods.  Direct from __user
 * buffer to osd, or directly to user pages (if O_DIRECT).
 *
 * If the read spans object boundary, just do multiple reads.  (That's not
 * atomic, but good enough for now.)
 *
 * If we get a short result from the OSD, check against i_size; we need to
 * only return a short read to the caller if we hit EOF.
 */
static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *to,
                              int *retry_op)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
        struct ceph_osd_client *osdc = &fsc->client->osdc;
        ssize_t ret;
        u64 off = iocb->ki_pos;
        u64 len = iov_iter_count(to);

        dout("sync_read on file %p %llu~%u %s\n", file, off, (unsigned)len,
             (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");

        if (!len)
                return 0;
        /*
         * flush any page cache pages in this range.  this
         * will make concurrent normal and sync io slow,
         * but it will at least behave sensibly when they are
         * in sequence.
         */
        ret = filemap_write_and_wait_range(inode->i_mapping,
                                           off, off + len - 1);
        if (ret < 0)
                return ret;

        ret = 0;
        while ((len = iov_iter_count(to)) > 0) {
                struct ceph_osd_request *req;
                struct page **pages;
                int num_pages;
                size_t page_off;
                u64 i_size;
                bool more;
                int idx;
                size_t left;

                req = ceph_osdc_new_request(osdc, &ci->i_layout,
                                        ci->i_vino, off, &len, 0, 1,
                                        CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
                                        NULL, ci->i_truncate_seq,
                                        ci->i_truncate_size, false);
                if (IS_ERR(req)) {
                        ret = PTR_ERR(req);
                        break;
                }

                more = len < iov_iter_count(to);

                num_pages = calc_pages_for(off, len);
                page_off = off & ~PAGE_MASK;
                pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);
                if (IS_ERR(pages)) {
                        ceph_osdc_put_request(req);
                        ret = PTR_ERR(pages);
                        break;
                }

                osd_req_op_extent_osd_data_pages(req, 0, pages, len, page_off,
                                                 false, false);
                ret = ceph_osdc_start_request(osdc, req, false);
                if (!ret)
                        ret = ceph_osdc_wait_request(osdc, req);

                ceph_update_read_latency(&fsc->mdsc->metric,
                                         req->r_start_latency,
                                         req->r_end_latency,
                                         ret);

                ceph_osdc_put_request(req);

                i_size = i_size_read(inode);
                dout("sync_read %llu~%llu got %zd i_size %llu%s\n",
                     off, len, ret, i_size, (more ? " MORE" : ""));

                if (ret == -ENOENT)
                        ret = 0;
                if (ret >= 0 && ret < len && (off + ret < i_size)) {
                        int zlen = min(len - ret, i_size - off - ret);
                        int zoff = page_off + ret;
                        dout("sync_read zero gap %llu~%llu\n",
                             off + ret, off + ret + zlen);
                        ceph_zero_page_vector_range(zoff, zlen, pages);
                        ret += zlen;
                }

                idx = 0;
                left = ret > 0 ? ret : 0;
                while (left > 0) {
                        size_t len, copied;
                        page_off = off & ~PAGE_MASK;
                        len = min_t(size_t, left, PAGE_SIZE - page_off);
                        SetPageUptodate(pages[idx]);
                        copied = copy_page_to_iter(pages[idx++],
                                                   page_off, len, to);
                        off += copied;
                        left -= copied;
                        if (copied < len) {
                                ret = -EFAULT;
                                break;
                        }
                }
                ceph_release_page_vector(pages, num_pages);

                if (ret < 0) {
                        if (ret == -EBLOCKLISTED)
                                fsc->blocklisted = true;
                        break;
                }

                if (off >= i_size || !more)
                        break;
        }

        if (off > iocb->ki_pos) {
                if (ret >= 0 &&
                    iov_iter_count(to) > 0 && off >= i_size_read(inode))
                        *retry_op = CHECK_EOF;
                ret = off - iocb->ki_pos;
                iocb->ki_pos = off;
        }

        dout("sync_read result %zd retry_op %d\n", ret, *retry_op);
        return ret;
}

struct ceph_aio_request {
        struct kiocb *iocb;
        size_t total_len;
        bool write;
        bool should_dirty;
        int error;
        struct list_head osd_reqs;
        unsigned num_reqs;
        atomic_t pending_reqs;
        struct timespec64 mtime;
        struct ceph_cap_flush *prealloc_cf;
};

struct ceph_aio_work {
        struct work_struct work;
        struct ceph_osd_request *req;
};

static void ceph_aio_retry_work(struct work_struct *work);

static void ceph_aio_complete(struct inode *inode,
                              struct ceph_aio_request *aio_req)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        int ret;

        if (!atomic_dec_and_test(&aio_req->pending_reqs))
                return;

        if (aio_req->iocb->ki_flags & IOCB_DIRECT)
                inode_dio_end(inode);

        ret = aio_req->error;
        if (!ret)
                ret = aio_req->total_len;

        dout("ceph_aio_complete %p rc %d\n", inode, ret);

        if (ret >= 0 && aio_req->write) {
                int dirty;

                loff_t endoff = aio_req->iocb->ki_pos + aio_req->total_len;
                if (endoff > i_size_read(inode)) {
                        if (ceph_inode_set_size(inode, endoff))

                                ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
                }

                spin_lock(&ci->i_ceph_lock);
                ci->i_inline_version = CEPH_INLINE_NONE;
                dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
                                               &aio_req->prealloc_cf);
                spin_unlock(&ci->i_ceph_lock);
                if (dirty)
                        __mark_inode_dirty(inode, dirty);

        }

        ceph_put_cap_refs(ci, (aio_req->write ? CEPH_CAP_FILE_WR :
                                                CEPH_CAP_FILE_RD));

        aio_req->iocb->ki_complete(aio_req->iocb, ret, 0);

        ceph_free_cap_flush(aio_req->prealloc_cf);
        kfree(aio_req);
}

static void ceph_aio_complete_req(struct ceph_osd_request *req)
{
        int rc = req->r_result;
        struct inode *inode = req->r_inode;
        struct ceph_aio_request *aio_req = req->r_priv;
        struct ceph_osd_data *osd_data = osd_req_op_extent_osd_data(req, 0);
        struct ceph_client_metric *metric = &ceph_sb_to_mdsc(inode->i_sb)->metric;

        BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_BVECS);
        BUG_ON(!osd_data->num_bvecs);

        dout("ceph_aio_complete_req %p rc %d bytes %u\n",
             inode, rc, osd_data->bvec_pos.iter.bi_size);

        /* r_start_latency == 0 means the request was not submitted */
        if (req->r_start_latency) {
                if (aio_req->write)
                        ceph_update_write_latency(metric, req->r_start_latency,
                                                  req->r_end_latency, rc);
                else
                        ceph_update_read_latency(metric, req->r_start_latency,
                                                 req->r_end_latency, rc);
        }

        if (rc == -EOLDSNAPC) {
                struct ceph_aio_work *aio_work;
                BUG_ON(!aio_req->write);

                aio_work = kmalloc(sizeof(*aio_work), GFP_NOFS);
                if (aio_work) {
                        INIT_WORK(&aio_work->work, ceph_aio_retry_work);
                        aio_work->req = req;
                        queue_work(ceph_inode_to_client(inode)->inode_wq,
                                   &aio_work->work);
                        return;
                }
                rc = -ENOMEM;
        } else if (!aio_req->write) {
                if (rc == -ENOENT)
                        rc = 0;
                if (rc >= 0 && osd_data->bvec_pos.iter.bi_size > rc) {
                        struct iov_iter i;
                        int zlen = osd_data->bvec_pos.iter.bi_size - rc;

                        /*
                         * If read is satisfied by single OSD request,
                         * it can pass EOF. Otherwise read is within
                         * i_size.
                         */
                        if (aio_req->num_reqs == 1) {
                                loff_t i_size = i_size_read(inode);
                                loff_t endoff = aio_req->iocb->ki_pos + rc;
                                if (endoff < i_size)
                                        zlen = min_t(size_t, zlen,
                                                     i_size - endoff);
                                aio_req->total_len = rc + zlen;
                        }

                        iov_iter_bvec(&i, READ, osd_data->bvec_pos.bvecs,
                                      osd_data->num_bvecs,
                                      osd_data->bvec_pos.iter.bi_size);
                        iov_iter_advance(&i, rc);
                        iov_iter_zero(zlen, &i);
                }
        }

        put_bvecs(osd_data->bvec_pos.bvecs, osd_data->num_bvecs,
                  aio_req->should_dirty);
        ceph_osdc_put_request(req);

        if (rc < 0)
                cmpxchg(&aio_req->error, 0, rc);

        ceph_aio_complete(inode, aio_req);
        return;
}

static void ceph_aio_retry_work(struct work_struct *work)
{
        struct ceph_aio_work *aio_work =
                container_of(work, struct ceph_aio_work, work);
        struct ceph_osd_request *orig_req = aio_work->req;
        struct ceph_aio_request *aio_req = orig_req->r_priv;
        struct inode *inode = orig_req->r_inode;
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_snap_context *snapc;
        struct ceph_osd_request *req;
        int ret;

        spin_lock(&ci->i_ceph_lock);
        if (__ceph_have_pending_cap_snap(ci)) {
                struct ceph_cap_snap *capsnap =
                        list_last_entry(&ci->i_cap_snaps,
                                        struct ceph_cap_snap,
                                        ci_item);
                snapc = ceph_get_snap_context(capsnap->context);
        } else {
                BUG_ON(!ci->i_head_snapc);
                snapc = ceph_get_snap_context(ci->i_head_snapc);
        }
        spin_unlock(&ci->i_ceph_lock);

        req = ceph_osdc_alloc_request(orig_req->r_osdc, snapc, 1,
                        false, GFP_NOFS);
        if (!req) {
                ret = -ENOMEM;
                req = orig_req;
                goto out;
        }

        req->r_flags = /* CEPH_OSD_FLAG_ORDERSNAP | */ CEPH_OSD_FLAG_WRITE;
        ceph_oloc_copy(&req->r_base_oloc, &orig_req->r_base_oloc);
        ceph_oid_copy(&req->r_base_oid, &orig_req->r_base_oid);

        req->r_ops[0] = orig_req->r_ops[0];

        req->r_mtime = aio_req->mtime;
        req->r_data_offset = req->r_ops[0].extent.offset;

        ret = ceph_osdc_alloc_messages(req, GFP_NOFS);
        if (ret) {
                ceph_osdc_put_request(req);
                req = orig_req;
                goto out;
        }

        ceph_osdc_put_request(orig_req);

        req->r_callback = ceph_aio_complete_req;
        req->r_inode = inode;
        req->r_priv = aio_req;

        ret = ceph_osdc_start_request(req->r_osdc, req, false);
out:
        if (ret < 0) {
                req->r_result = ret;
                ceph_aio_complete_req(req);
        }

        ceph_put_snap_context(snapc);
        kfree(aio_work);
}

static ssize_t
ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter,
                       struct ceph_snap_context *snapc,
                       struct ceph_cap_flush **pcf)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
        struct ceph_client_metric *metric = &fsc->mdsc->metric;
        struct ceph_vino vino;
        struct ceph_osd_request *req;
        struct bio_vec *bvecs;
        struct ceph_aio_request *aio_req = NULL;
        int num_pages = 0;
        int flags;
        int ret = 0;
        struct timespec64 mtime = current_time(inode);
        size_t count = iov_iter_count(iter);
        loff_t pos = iocb->ki_pos;
        bool write = iov_iter_rw(iter) == WRITE;
        bool should_dirty = !write && iter_is_iovec(iter);

        if (write && ceph_snap(file_inode(file)) != CEPH_NOSNAP)
                return -EROFS;

        dout("sync_direct_%s on file %p %lld~%u snapc %p seq %lld\n",
             (write ? "write" : "read"), file, pos, (unsigned)count,
             snapc, snapc ? snapc->seq : 0);

        if (write) {
                int ret2 = invalidate_inode_pages2_range(inode->i_mapping,
                                        pos >> PAGE_SHIFT,
                                        (pos + count - 1) >> PAGE_SHIFT);
                if (ret2 < 0)
                        dout("invalidate_inode_pages2_range returned %d\n", ret2);

                flags = /* CEPH_OSD_FLAG_ORDERSNAP | */ CEPH_OSD_FLAG_WRITE;
        } else {
                flags = CEPH_OSD_FLAG_READ;
        }

        while (iov_iter_count(iter) > 0) {
                u64 size = iov_iter_count(iter);
                ssize_t len;

                if (write)
                        size = min_t(u64, size, fsc->mount_options->wsize);
                else
                        size = min_t(u64, size, fsc->mount_options->rsize);

                vino = ceph_vino(inode);
                req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
                                            vino, pos, &size, 0,
                                            1,
                                            write ? CEPH_OSD_OP_WRITE :
                                                    CEPH_OSD_OP_READ,
                                            flags, snapc,
                                            ci->i_truncate_seq,
                                            ci->i_truncate_size,
                                            false);
                if (IS_ERR(req)) {
                        ret = PTR_ERR(req);
                        break;
                }

                len = iter_get_bvecs_alloc(iter, size, &bvecs, &num_pages);
                if (len < 0) {
                        ceph_osdc_put_request(req);
                        ret = len;
                        break;
                }
                if (len != size)
                        osd_req_op_extent_update(req, 0, len);

                /*
                 * To simplify error handling, allow AIO when IO within i_size
                 * or IO can be satisfied by single OSD request.
                 */
                if (pos == iocb->ki_pos && !is_sync_kiocb(iocb) &&
                    (len == count || pos + count <= i_size_read(inode))) {
                        aio_req = kzalloc(sizeof(*aio_req), GFP_KERNEL);
                        if (aio_req) {
                                aio_req->iocb = iocb;
                                aio_req->write = write;
                                aio_req->should_dirty = should_dirty;
                                INIT_LIST_HEAD(&aio_req->osd_reqs);
                                if (write) {
                                        aio_req->mtime = mtime;
                                        swap(aio_req->prealloc_cf, *pcf);
                                }
                        }
                        /* ignore error */
                }

                if (write) {
                        /*
                         * throw out any page cache pages in this range. this
                         * may block.
                         */
                        truncate_inode_pages_range(inode->i_mapping, pos,
                                                   PAGE_ALIGN(pos + len) - 1);

                        req->r_mtime = mtime;
                }

                osd_req_op_extent_osd_data_bvecs(req, 0, bvecs, num_pages, len);

                if (aio_req) {
                        aio_req->total_len += len;
                        aio_req->num_reqs++;
                        atomic_inc(&aio_req->pending_reqs);

                        req->r_callback = ceph_aio_complete_req;
                        req->r_inode = inode;
                        req->r_priv = aio_req;
                        list_add_tail(&req->r_private_item, &aio_req->osd_reqs);

                        pos += len;
                        continue;
                }

                ret = ceph_osdc_start_request(req->r_osdc, req, false);
                if (!ret)
                        ret = ceph_osdc_wait_request(&fsc->client->osdc, req);

                if (write)
                        ceph_update_write_latency(metric, req->r_start_latency,
                                                  req->r_end_latency, ret);
                else
                        ceph_update_read_latency(metric, req->r_start_latency,
                                                 req->r_end_latency, ret);

                size = i_size_read(inode);
                if (!write) {
                        if (ret == -ENOENT)
                                ret = 0;
                        if (ret >= 0 && ret < len && pos + ret < size) {
                                struct iov_iter i;
                                int zlen = min_t(size_t, len - ret,
                                                 size - pos - ret);

                                iov_iter_bvec(&i, READ, bvecs, num_pages, len);
                                iov_iter_advance(&i, ret);
                                iov_iter_zero(zlen, &i);
                                ret += zlen;
                        }
                        if (ret >= 0)
                                len = ret;
                }

                put_bvecs(bvecs, num_pages, should_dirty);
                ceph_osdc_put_request(req);
                if (ret < 0)
                        break;

                pos += len;
                if (!write && pos >= size)
                        break;

                if (write && pos > size) {
                        if (ceph_inode_set_size(inode, pos))
                                ceph_check_caps(ceph_inode(inode),
                                                CHECK_CAPS_AUTHONLY,
                                                NULL);
                }
        }

        if (aio_req) {
                LIST_HEAD(osd_reqs);

                if (aio_req->num_reqs == 0) {
                        kfree(aio_req);
                        return ret;
                }

                ceph_get_cap_refs(ci, write ? CEPH_CAP_FILE_WR :
                                              CEPH_CAP_FILE_RD);

                list_splice(&aio_req->osd_reqs, &osd_reqs);
                inode_dio_begin(inode);
                while (!list_empty(&osd_reqs)) {
                        req = list_first_entry(&osd_reqs,
                                               struct ceph_osd_request,
                                               r_private_item);
                        list_del_init(&req->r_private_item);
                        if (ret >= 0)
                                ret = ceph_osdc_start_request(req->r_osdc,
                                                              req, false);
                        if (ret < 0) {
                                req->r_result = ret;
                                ceph_aio_complete_req(req);
                        }
                }
                return -EIOCBQUEUED;
        }

        if (ret != -EOLDSNAPC && pos > iocb->ki_pos) {
                ret = pos - iocb->ki_pos;
                iocb->ki_pos = pos;
        }
        return ret;
}

/*
 * Synchronous write, straight from __user pointer or user pages.
 *
 * If write spans object boundary, just do multiple writes.  (For a
 * correct atomic write, we should e.g. take write locks on all
 * objects, rollback on failure, etc.)
 */
static ssize_t
ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos,
                struct ceph_snap_context *snapc)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
        struct ceph_vino vino;
        struct ceph_osd_request *req;
        struct page **pages;
        u64 len;
        int num_pages;
        int written = 0;
        int flags;
        int ret;
        bool check_caps = false;
        struct timespec64 mtime = current_time(inode);
        size_t count = iov_iter_count(from);

        if (ceph_snap(file_inode(file)) != CEPH_NOSNAP)
                return -EROFS;

        dout("sync_write on file %p %lld~%u snapc %p seq %lld\n",
             file, pos, (unsigned)count, snapc, snapc->seq);

        ret = filemap_write_and_wait_range(inode->i_mapping,
                                           pos, pos + count - 1);
        if (ret < 0)
                return ret;

        ret = invalidate_inode_pages2_range(inode->i_mapping,
                                            pos >> PAGE_SHIFT,
                                            (pos + count - 1) >> PAGE_SHIFT);
        if (ret < 0)
                dout("invalidate_inode_pages2_range returned %d\n", ret);

        flags = /* CEPH_OSD_FLAG_ORDERSNAP | */ CEPH_OSD_FLAG_WRITE;

        while ((len = iov_iter_count(from)) > 0) {
                size_t left;
                int n;

                vino = ceph_vino(inode);
                req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
                                            vino, pos, &len, 0, 1,
                                            CEPH_OSD_OP_WRITE, flags, snapc,
                                            ci->i_truncate_seq,
                                            ci->i_truncate_size,
                                            false);
                if (IS_ERR(req)) {
                        ret = PTR_ERR(req);
                        break;
                }

                /*
                 * write from beginning of first page,
                 * regardless of io alignment
                 */
                num_pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;

                pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);
                if (IS_ERR(pages)) {
                        ret = PTR_ERR(pages);
                        goto out;
                }

                left = len;
                for (n = 0; n < num_pages; n++) {
                        size_t plen = min_t(size_t, left, PAGE_SIZE);
                        ret = copy_page_from_iter(pages[n], 0, plen, from);
                        if (ret != plen) {
                                ret = -EFAULT;
                                break;
                        }
                        left -= ret;
                }

                if (ret < 0) {
                        ceph_release_page_vector(pages, num_pages);
                        goto out;
                }

                req->r_inode = inode;

                osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0,
                                                false, true);

                req->r_mtime = mtime;
                ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
                if (!ret)
                        ret = ceph_osdc_wait_request(&fsc->client->osdc, req);

                ceph_update_write_latency(&fsc->mdsc->metric, req->r_start_latency,
                                          req->r_end_latency, ret);
out:
                ceph_osdc_put_request(req);
                if (ret != 0) {
                        ceph_set_error_write(ci);
                        break;
                }

                ceph_clear_error_write(ci);
                pos += len;
                written += len;
                if (pos > i_size_read(inode)) {
                        check_caps = ceph_inode_set_size(inode, pos);
                        if (check_caps)
                                ceph_check_caps(ceph_inode(inode),
                                                CHECK_CAPS_AUTHONLY,
                                                NULL);
                }

        }

        if (ret != -EOLDSNAPC && written > 0) {
                ret = written;
                iocb->ki_pos = pos;
        }
        return ret;
}

/*
 * Wrap generic_file_aio_read with checks for cap bits on the inode.
 * Atomically grab references, so that those bits are not released
 * back to the MDS mid-read.
 *
 * Hmm, the sync read case isn't actually async... should it be?
 */
static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
        struct file *filp = iocb->ki_filp;
        struct ceph_file_info *fi = filp->private_data;
        size_t len = iov_iter_count(to);
        struct inode *inode = file_inode(filp);
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct page *pinned_page = NULL;
        bool direct_lock = iocb->ki_flags & IOCB_DIRECT;
        ssize_t ret;
        int want, got = 0;
        int retry_op = 0, read = 0;

again:
        dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
             inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, inode);

        if (direct_lock)
                ceph_start_io_direct(inode);
        else
                ceph_start_io_read(inode);

        if (fi->fmode & CEPH_FILE_MODE_LAZY)
                want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
        else
                want = CEPH_CAP_FILE_CACHE;
        ret = ceph_get_caps(filp, CEPH_CAP_FILE_RD, want, -1,
                            &got, &pinned_page);
        if (ret < 0) {
                if (iocb->ki_flags & IOCB_DIRECT)
                        ceph_end_io_direct(inode);
                else
                        ceph_end_io_read(inode);
                return ret;
        }

        if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
            (iocb->ki_flags & IOCB_DIRECT) ||
            (fi->flags & CEPH_F_SYNC)) {

                dout("aio_sync_read %p %llx.%llx %llu~%u got cap refs on %s\n",
                     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
                     ceph_cap_string(got));

                if (ci->i_inline_version == CEPH_INLINE_NONE) {
                        if (!retry_op && (iocb->ki_flags & IOCB_DIRECT)) {
                                ret = ceph_direct_read_write(iocb, to,
                                                             NULL, NULL);
                                if (ret >= 0 && ret < len)
                                        retry_op = CHECK_EOF;
                        } else {
                                ret = ceph_sync_read(iocb, to, &retry_op);
                        }
                } else {
                        retry_op = READ_INLINE;
                }
        } else {
                CEPH_DEFINE_RW_CONTEXT(rw_ctx, got);
                dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s\n",
                     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
                     ceph_cap_string(got));
                ceph_add_rw_context(fi, &rw_ctx);
                ret = generic_file_read_iter(iocb, to);
                ceph_del_rw_context(fi, &rw_ctx);
        }

        dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",
             inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
        if (pinned_page) {
                put_page(pinned_page);
                pinned_page = NULL;
        }
        ceph_put_cap_refs(ci, got);

        if (direct_lock)
                ceph_end_io_direct(inode);
        else
                ceph_end_io_read(inode);

        if (retry_op > HAVE_RETRIED && ret >= 0) {
                int statret;
                struct page *page = NULL;
                loff_t i_size;
                if (retry_op == READ_INLINE) {
                        page = __page_cache_alloc(GFP_KERNEL);
                        if (!page)
                                return -ENOMEM;
                }

                statret = __ceph_do_getattr(inode, page,
                                            CEPH_STAT_CAP_INLINE_DATA, !!page);
                if (statret < 0) {
                        if (page)
                                __free_page(page);
                        if (statret == -ENODATA) {
                                BUG_ON(retry_op != READ_INLINE);
                                goto again;
                        }
                        return statret;
                }

                i_size = i_size_read(inode);
                if (retry_op == READ_INLINE) {
                        BUG_ON(ret > 0 || read > 0);
                        if (iocb->ki_pos < i_size &&
                            iocb->ki_pos < PAGE_SIZE) {
                                loff_t end = min_t(loff_t, i_size,
                                                   iocb->ki_pos + len);
                                end = min_t(loff_t, end, PAGE_SIZE);
                                if (statret < end)
                                        zero_user_segment(page, statret, end);
                                ret = copy_page_to_iter(page,
                                                iocb->ki_pos & ~PAGE_MASK,
                                                end - iocb->ki_pos, to);
                                iocb->ki_pos += ret;
                                read += ret;
                        }
                        if (iocb->ki_pos < i_size && read < len) {
                                size_t zlen = min_t(size_t, len - read,
                                                    i_size - iocb->ki_pos);
                                ret = iov_iter_zero(zlen, to);
                                iocb->ki_pos += ret;
                                read += ret;
                        }
                        __free_pages(page, 0);
                        return read;
                }

                /* hit EOF or hole? */
                if (retry_op == CHECK_EOF && iocb->ki_pos < i_size &&
                    ret < len) {
                        dout("sync_read hit hole, ppos %lld < size %lld"
                             ", reading more\n", iocb->ki_pos, i_size);

                        read += ret;
                        len -= ret;
                        retry_op = HAVE_RETRIED;
                        goto again;
                }
        }

        if (ret >= 0)
                ret += read;

        return ret;
}

/*
 * Take cap references to avoid releasing caps to MDS mid-write.
 *
 * If we are synchronous, and write with an old snap context, the OSD
 * may return EOLDSNAPC.  In that case, retry the write.. _after_
 * dropping our cap refs and allowing the pending snap to logically
 * complete _before_ this write occurs.
 *
 * If we are near ENOSPC, write synchronously.
 */
static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
        struct file *file = iocb->ki_filp;
        struct ceph_file_info *fi = file->private_data;
        struct inode *inode = file_inode(file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
        struct ceph_osd_client *osdc = &fsc->client->osdc;
        struct ceph_cap_flush *prealloc_cf;
        ssize_t count, written = 0;
        int err, want, got;
        bool direct_lock = false;
        u32 map_flags;
        u64 pool_flags;
        loff_t pos;
        loff_t limit = max(i_size_read(inode), fsc->max_file_size);

        if (ceph_snap(inode) != CEPH_NOSNAP)
                return -EROFS;

        prealloc_cf = ceph_alloc_cap_flush();
        if (!prealloc_cf)
                return -ENOMEM;

        if ((iocb->ki_flags & (IOCB_DIRECT | IOCB_APPEND)) == IOCB_DIRECT)
                direct_lock = true;

retry_snap:
        if (direct_lock)
                ceph_start_io_direct(inode);
        else
                ceph_start_io_write(inode);

        /* We can write back this queue in page reclaim */
        current->backing_dev_info = inode_to_bdi(inode);

        if (iocb->ki_flags & IOCB_APPEND) {
                err = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE, false);
                if (err < 0)
                        goto out;
        }

        err = generic_write_checks(iocb, from);
        if (err <= 0)
                goto out;

        pos = iocb->ki_pos;
        if (unlikely(pos >= limit)) {
                err = -EFBIG;
                goto out;
        } else {
                iov_iter_truncate(from, limit - pos);
        }

        count = iov_iter_count(from);
        if (ceph_quota_is_max_bytes_exceeded(inode, pos + count)) {
                err = -EDQUOT;
                goto out;
        }

        err = file_remove_privs(file);
        if (err)
                goto out;

        err = file_update_time(file);
        if (err)
                goto out;

        inode_inc_iversion_raw(inode);

        if (ci->i_inline_version != CEPH_INLINE_NONE) {
                err = ceph_uninline_data(file, NULL);
                if (err < 0)
                        goto out;
        }

        down_read(&osdc->lock);
        map_flags = osdc->osdmap->flags;
        pool_flags = ceph_pg_pool_flags(osdc->osdmap, ci->i_layout.pool_id);
        up_read(&osdc->lock);
        if ((map_flags & CEPH_OSDMAP_FULL) ||
            (pool_flags & CEPH_POOL_FLAG_FULL)) {
                err = -ENOSPC;
                goto out;
        }

        dout("aio_write %p %llx.%llx %llu~%zd getting caps. i_size %llu\n",
             inode, ceph_vinop(inode), pos, count, i_size_read(inode));
        if (fi->fmode & CEPH_FILE_MODE_LAZY)
                want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
        else
                want = CEPH_CAP_FILE_BUFFER;
        got = 0;
        err = ceph_get_caps(file, CEPH_CAP_FILE_WR, want, pos + count,
                            &got, NULL);
        if (err < 0)
                goto out;

        dout("aio_write %p %llx.%llx %llu~%zd got cap refs on %s\n",
             inode, ceph_vinop(inode), pos, count, ceph_cap_string(got));

        if ((got & (CEPH_CAP_FILE_BUFFER|CEPH_CAP_FILE_LAZYIO)) == 0 ||
            (iocb->ki_flags & IOCB_DIRECT) || (fi->flags & CEPH_F_SYNC) ||
            (ci->i_ceph_flags & CEPH_I_ERROR_WRITE)) {
                struct ceph_snap_context *snapc;
                struct iov_iter data;

                spin_lock(&ci->i_ceph_lock);
                if (__ceph_have_pending_cap_snap(ci)) {
                        struct ceph_cap_snap *capsnap =
                                        list_last_entry(&ci->i_cap_snaps,
                                                        struct ceph_cap_snap,
                                                        ci_item);
                        snapc = ceph_get_snap_context(capsnap->context);
                } else {
                        BUG_ON(!ci->i_head_snapc);
                        snapc = ceph_get_snap_context(ci->i_head_snapc);
                }
                spin_unlock(&ci->i_ceph_lock);

                /* we might need to revert back to that point */
                data = *from;
                if (iocb->ki_flags & IOCB_DIRECT)
                        written = ceph_direct_read_write(iocb, &data, snapc,
                                                         &prealloc_cf);
                else
                        written = ceph_sync_write(iocb, &data, pos, snapc);
                if (direct_lock)
                        ceph_end_io_direct(inode);
                else
                        ceph_end_io_write(inode);
                if (written > 0)
                        iov_iter_advance(from, written);
                ceph_put_snap_context(snapc);
        } else {
                /*
                 * No need to acquire the i_truncate_mutex. Because
                 * the MDS revokes Fwb caps before sending truncate
                 * message to us. We can't get Fwb cap while there
                 * are pending vmtruncate. So write and vmtruncate
                 * can not run at the same time
                 */
                written = generic_perform_write(file, from, pos);
                if (likely(written >= 0))
                        iocb->ki_pos = pos + written;
                ceph_end_io_write(inode);
        }

        if (written >= 0) {
                int dirty;

                spin_lock(&ci->i_ceph_lock);
                ci->i_inline_version = CEPH_INLINE_NONE;
                dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
                                               &prealloc_cf);
                spin_unlock(&ci->i_ceph_lock);
                if (dirty)
                        __mark_inode_dirty(inode, dirty);
                if (ceph_quota_is_max_bytes_approaching(inode, iocb->ki_pos))
                        ceph_check_caps(ci, 0, NULL);
        }

        dout("aio_write %p %llx.%llx %llu~%u  dropping cap refs on %s\n",
             inode, ceph_vinop(inode), pos, (unsigned)count,
             ceph_cap_string(got));
        ceph_put_cap_refs(ci, got);

        if (written == -EOLDSNAPC) {
                dout("aio_write %p %llx.%llx %llu~%u" "got EOLDSNAPC, retrying\n",
                     inode, ceph_vinop(inode), pos, (unsigned)count);
                goto retry_snap;
        }

        if (written >= 0) {
                if ((map_flags & CEPH_OSDMAP_NEARFULL) ||
                    (pool_flags & CEPH_POOL_FLAG_NEARFULL))
                        iocb->ki_flags |= IOCB_DSYNC;
                written = generic_write_sync(iocb, written);
        }

        goto out_unlocked;
out:
        if (direct_lock)
                ceph_end_io_direct(inode);
        else
                ceph_end_io_write(inode);
out_unlocked:
        ceph_free_cap_flush(prealloc_cf);
        current->backing_dev_info = NULL;
        return written ? written : err;
}

/*
 * llseek.  be sure to verify file size on SEEK_END.
 */
static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
{
        struct inode *inode = file->f_mapping->host;
        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
        loff_t i_size;
        loff_t ret;

        inode_lock(inode);

        if (whence == SEEK_END || whence == SEEK_DATA || whence == SEEK_HOLE) {
                ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE, false);
                if (ret < 0)
                        goto out;
        }

        i_size = i_size_read(inode);
        switch (whence) {
        case SEEK_END:
                offset += i_size;
                break;
        case SEEK_CUR:
                /*
                 * Here we special-case the lseek(fd, 0, SEEK_CUR)
                 * position-querying operation.  Avoid rewriting the "same"
                 * f_pos value back to the file because a concurrent read(),
                 * write() or lseek() might have altered it
                 */
                if (offset == 0) {
                        ret = file->f_pos;
                        goto out;
                }
                offset += file->f_pos;
                break;
        case SEEK_DATA:
                if (offset < 0 || offset >= i_size) {
                        ret = -ENXIO;
                        goto out;
                }
                break;
        case SEEK_HOLE:
                if (offset < 0 || offset >= i_size) {
                        ret = -ENXIO;
                        goto out;
                }
                offset = i_size;
                break;
        }

        ret = vfs_setpos(file, offset, max(i_size, fsc->max_file_size));

out:
        inode_unlock(inode);
        return ret;
}

static inline void ceph_zero_partial_page(
        struct inode *inode, loff_t offset, unsigned size)
{
        struct page *page;
        pgoff_t index = offset >> PAGE_SHIFT;

        page = find_lock_page(inode->i_mapping, index);
        if (page) {
                wait_on_page_writeback(page);
                zero_user(page, offset & (PAGE_SIZE - 1), size);
                unlock_page(page);
                put_page(page);
        }
}

static void ceph_zero_pagecache_range(struct inode *inode, loff_t offset,
                                      loff_t length)
{
        loff_t nearly = round_up(offset, PAGE_SIZE);
        if (offset < nearly) {
                loff_t size = nearly - offset;
                if (length < size)
                        size = length;
                ceph_zero_partial_page(inode, offset, size);
                offset += size;
                length -= size;
        }
        if (length >= PAGE_SIZE) {
                loff_t size = round_down(length, PAGE_SIZE);
                truncate_pagecache_range(inode, offset, offset + size - 1);
                offset += size;
                length -= size;
        }
        if (length)
                ceph_zero_partial_page(inode, offset, length);
}

static int ceph_zero_partial_object(struct inode *inode,
                                    loff_t offset, loff_t *length)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
        struct ceph_osd_request *req;
        int ret = 0;
        loff_t zero = 0;
        int op;

        if (!length) {
                op = offset ? CEPH_OSD_OP_DELETE : CEPH_OSD_OP_TRUNCATE;
                length = &zero;
        } else {
                op = CEPH_OSD_OP_ZERO;
        }

        req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
                                        ceph_vino(inode),
                                        offset, length,
                                        0, 1, op,
                                        CEPH_OSD_FLAG_WRITE,
                                        NULL, 0, 0, false);
        if (IS_ERR(req)) {
                ret = PTR_ERR(req);
                goto out;
        }

        req->r_mtime = inode->i_mtime;
        ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
        if (!ret) {
                ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
                if (ret == -ENOENT)
                        ret = 0;
        }
        ceph_osdc_put_request(req);

out:
        return ret;
}

static int ceph_zero_objects(struct inode *inode, loff_t offset, loff_t length)
{
        int ret = 0;
        struct ceph_inode_info *ci = ceph_inode(inode);
        s32 stripe_unit = ci->i_layout.stripe_unit;
        s32 stripe_count = ci->i_layout.stripe_count;
        s32 object_size = ci->i_layout.object_size;
        u64 object_set_size = object_size * stripe_count;
        u64 nearly, t;

        /* round offset up to next period boundary */
        nearly = offset + object_set_size - 1;
        t = nearly;
        nearly -= do_div(t, object_set_size);

        while (length && offset < nearly) {
                loff_t size = length;
                ret = ceph_zero_partial_object(inode, offset, &size);
                if (ret < 0)
                        return ret;
                offset += size;
                length -= size;
        }
        while (length >= object_set_size) {
                int i;
                loff_t pos = offset;
                for (i = 0; i < stripe_count; ++i) {
                        ret = ceph_zero_partial_object(inode, pos, NULL);
                        if (ret < 0)
                                return ret;
                        pos += stripe_unit;
                }
                offset += object_set_size;
                length -= object_set_size;
        }
        while (length) {
                loff_t size = length;
                ret = ceph_zero_partial_object(inode, offset, &size);
                if (ret < 0)
                        return ret;
                offset += size;
                length -= size;
        }
        return ret;
}

static long ceph_fallocate(struct file *file, int mode,
                                loff_t offset, loff_t length)
{
        struct ceph_file_info *fi = file->private_data;
        struct inode *inode = file_inode(file);
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_cap_flush *prealloc_cf;
        int want, got = 0;
        int dirty;
        int ret = 0;
        loff_t endoff = 0;
        loff_t size;

        if (mode != (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
                return -EOPNOTSUPP;

        if (!S_ISREG(inode->i_mode))
                return -EOPNOTSUPP;

        prealloc_cf = ceph_alloc_cap_flush();
        if (!prealloc_cf)
                return -ENOMEM;

        inode_lock(inode);

        if (ceph_snap(inode) != CEPH_NOSNAP) {
                ret = -EROFS;
                goto unlock;
        }

        if (ci->i_inline_version != CEPH_INLINE_NONE) {
                ret = ceph_uninline_data(file, NULL);
                if (ret < 0)
                        goto unlock;
        }

        size = i_size_read(inode);

        /* Are we punching a hole beyond EOF? */
        if (offset >= size)
                goto unlock;
        if ((offset + length) > size)
                length = size - offset;

        if (fi->fmode & CEPH_FILE_MODE_LAZY)
                want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
        else
                want = CEPH_CAP_FILE_BUFFER;

        ret = ceph_get_caps(file, CEPH_CAP_FILE_WR, want, endoff, &got, NULL);
        if (ret < 0)
                goto unlock;

        ceph_zero_pagecache_range(inode, offset, length);
        ret = ceph_zero_objects(inode, offset, length);

        if (!ret) {
                spin_lock(&ci->i_ceph_lock);
                ci->i_inline_version = CEPH_INLINE_NONE;
                dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
                                               &prealloc_cf);
                spin_unlock(&ci->i_ceph_lock);
                if (dirty)
                        __mark_inode_dirty(inode, dirty);
        }

        ceph_put_cap_refs(ci, got);
unlock:
        inode_unlock(inode);
        ceph_free_cap_flush(prealloc_cf);
        return ret;
}

/*
 * This function tries to get FILE_WR capabilities for dst_ci and FILE_RD for
 * src_ci.  Two attempts are made to obtain both caps, and an error is return if
 * this fails; zero is returned on success.
 */
static int get_rd_wr_caps(struct file *src_filp, int *src_got,
                          struct file *dst_filp,
                          loff_t dst_endoff, int *dst_got)
{
        int ret = 0;
        bool retrying = false;

retry_caps:
        ret = ceph_get_caps(dst_filp, CEPH_CAP_FILE_WR, CEPH_CAP_FILE_BUFFER,
                            dst_endoff, dst_got, NULL);
        if (ret < 0)
                return ret;

        /*
         * Since we're already holding the FILE_WR capability for the dst file,
         * we would risk a deadlock by using ceph_get_caps.  Thus, we'll do some
         * retry dance instead to try to get both capabilities.
         */
        ret = ceph_try_get_caps(file_inode(src_filp),
                                CEPH_CAP_FILE_RD, CEPH_CAP_FILE_SHARED,
                                false, src_got);
        if (ret <= 0) {
                /* Start by dropping dst_ci caps and getting src_ci caps */
                ceph_put_cap_refs(ceph_inode(file_inode(dst_filp)), *dst_got);
                if (retrying) {
                        if (!ret)
                                /* ceph_try_get_caps masks EAGAIN */
                                ret = -EAGAIN;
                        return ret;
                }
                ret = ceph_get_caps(src_filp, CEPH_CAP_FILE_RD,
                                    CEPH_CAP_FILE_SHARED, -1, src_got, NULL);
                if (ret < 0)
                        return ret;
                /*... drop src_ci caps too, and retry */
                ceph_put_cap_refs(ceph_inode(file_inode(src_filp)), *src_got);
                retrying = true;
                goto retry_caps;
        }
        return ret;
}

static void put_rd_wr_caps(struct ceph_inode_info *src_ci, int src_got,
                           struct ceph_inode_info *dst_ci, int dst_got)
{
        ceph_put_cap_refs(src_ci, src_got);
        ceph_put_cap_refs(dst_ci, dst_got);
}

/*
 * This function does several size-related checks, returning an error if:
 *  - source file is smaller than off+len
 *  - destination file size is not OK (inode_newsize_ok())
 *  - max bytes quotas is exceeded
 */
static int is_file_size_ok(struct inode *src_inode, struct inode *dst_inode,
                           loff_t src_off, loff_t dst_off, size_t len)
{
        loff_t size, endoff;

        size = i_size_read(src_inode);
        /*
         * Don't copy beyond source file EOF.  Instead of simply setting length
         * to (size - src_off), just drop to VFS default implementation, as the
         * local i_size may be stale due to other clients writing to the source
         * inode.
         */
        if (src_off + len > size) {
                dout("Copy beyond EOF (%llu + %zu > %llu)\n",
                     src_off, len, size);
                return -EOPNOTSUPP;
        }
        size = i_size_read(dst_inode);

        endoff = dst_off + len;
        if (inode_newsize_ok(dst_inode, endoff))
                return -EOPNOTSUPP;

        if (ceph_quota_is_max_bytes_exceeded(dst_inode, endoff))
                return -EDQUOT;

        return 0;
}

static ssize_t ceph_do_objects_copy(struct ceph_inode_info *src_ci, u64 *src_off,
                                    struct ceph_inode_info *dst_ci, u64 *dst_off,
                                    struct ceph_fs_client *fsc,
                                    size_t len, unsigned int flags)
{
        struct ceph_object_locator src_oloc, dst_oloc;
        struct ceph_object_id src_oid, dst_oid;
        size_t bytes = 0;
        u64 src_objnum, src_objoff, dst_objnum, dst_objoff;
        u32 src_objlen, dst_objlen;
        u32 object_size = src_ci->i_layout.object_size;
        int ret;

        src_oloc.pool = src_ci->i_layout.pool_id;
        src_oloc.pool_ns = ceph_try_get_string(src_ci->i_layout.pool_ns);
        dst_oloc.pool = dst_ci->i_layout.pool_id;
        dst_oloc.pool_ns = ceph_try_get_string(dst_ci->i_layout.pool_ns);

        while (len >= object_size) {
                ceph_calc_file_object_mapping(&src_ci->i_layout, *src_off,
                                              object_size, &src_objnum,
                                              &src_objoff, &src_objlen);
                ceph_calc_file_object_mapping(&dst_ci->i_layout, *dst_off,
                                              object_size, &dst_objnum,
                                              &dst_objoff, &dst_objlen);
                ceph_oid_init(&src_oid);
                ceph_oid_printf(&src_oid, "%llx.%08llx",
                                src_ci->i_vino.ino, src_objnum);
                ceph_oid_init(&dst_oid);
                ceph_oid_printf(&dst_oid, "%llx.%08llx",
                                dst_ci->i_vino.ino, dst_objnum);
                /* Do an object remote copy */
                ret = ceph_osdc_copy_from(&fsc->client->osdc,
                                          src_ci->i_vino.snap, 0,
                                          &src_oid, &src_oloc,
                                          CEPH_OSD_OP_FLAG_FADVISE_SEQUENTIAL |
                                          CEPH_OSD_OP_FLAG_FADVISE_NOCACHE,
                                          &dst_oid, &dst_oloc,
                                          CEPH_OSD_OP_FLAG_FADVISE_SEQUENTIAL |
                                          CEPH_OSD_OP_FLAG_FADVISE_DONTNEED,
                                          dst_ci->i_truncate_seq,
                                          dst_ci->i_truncate_size,
                                          CEPH_OSD_COPY_FROM_FLAG_TRUNCATE_SEQ);
                if (ret) {
                        if (ret == -EOPNOTSUPP) {
                                fsc->have_copy_from2 = false;
                                pr_notice("OSDs don't support copy-from2; disabling copy offload\n");
                        }
                        dout("ceph_osdc_copy_from returned %d\n", ret);
                        if (!bytes)
                                bytes = ret;
                        goto out;
                }
                len -= object_size;
                bytes += object_size;
                *src_off += object_size;
                *dst_off += object_size;
        }

out:
        ceph_oloc_destroy(&src_oloc);
        ceph_oloc_destroy(&dst_oloc);
        return bytes;
}

static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
                                      struct file *dst_file, loff_t dst_off,
                                      size_t len, unsigned int flags)
{
        struct inode *src_inode = file_inode(src_file);
        struct inode *dst_inode = file_inode(dst_file);
        struct ceph_inode_info *src_ci = ceph_inode(src_inode);
        struct ceph_inode_info *dst_ci = ceph_inode(dst_inode);
        struct ceph_cap_flush *prealloc_cf;
        struct ceph_fs_client *src_fsc = ceph_inode_to_client(src_inode);
        loff_t size;
        ssize_t ret = -EIO, bytes;
        u64 src_objnum, dst_objnum, src_objoff, dst_objoff;
        u32 src_objlen, dst_objlen;
        int src_got = 0, dst_got = 0, err, dirty;

        if (src_inode->i_sb != dst_inode->i_sb) {
                struct ceph_fs_client *dst_fsc = ceph_inode_to_client(dst_inode);

                if (ceph_fsid_compare(&src_fsc->client->fsid,
                                      &dst_fsc->client->fsid)) {
                        dout("Copying files across clusters: src: %pU dst: %pU\n",
                             &src_fsc->client->fsid, &dst_fsc->client->fsid);
                        return -EXDEV;
                }
        }
        if (ceph_snap(dst_inode) != CEPH_NOSNAP)
                return -EROFS;

        /*
         * Some of the checks below will return -EOPNOTSUPP, which will force a
         * fallback to the default VFS copy_file_range implementation.  This is
         * desirable in several cases (for ex, the 'len' is smaller than the
         * size of the objects, or in cases where that would be more
         * efficient).
         */

        if (ceph_test_mount_opt(src_fsc, NOCOPYFROM))
                return -EOPNOTSUPP;

        if (!src_fsc->have_copy_from2)
                return -EOPNOTSUPP;

        /*
         * Striped file layouts require that we copy partial objects, but the
         * OSD copy-from operation only supports full-object copies.  Limit
         * this to non-striped file layouts for now.
         */
        if ((src_ci->i_layout.stripe_unit != dst_ci->i_layout.stripe_unit) ||
            (src_ci->i_layout.stripe_count != 1) ||
            (dst_ci->i_layout.stripe_count != 1) ||
            (src_ci->i_layout.object_size != dst_ci->i_layout.object_size)) {
                dout("Invalid src/dst files layout\n");
                return -EOPNOTSUPP;
        }

        if (len < src_ci->i_layout.object_size)
                return -EOPNOTSUPP; /* no remote copy will be done */

        prealloc_cf = ceph_alloc_cap_flush();
        if (!prealloc_cf)
                return -ENOMEM;

        /* Start by sync'ing the source and destination files */
        ret = file_write_and_wait_range(src_file, src_off, (src_off + len));
        if (ret < 0) {
                dout("failed to write src file (%zd)\n", ret);
                goto out;
        }
        ret = file_write_and_wait_range(dst_file, dst_off, (dst_off + len));
        if (ret < 0) {
                dout("failed to write dst file (%zd)\n", ret);
                goto out;
        }

        /*
         * We need FILE_WR caps for dst_ci and FILE_RD for src_ci as other
         * clients may have dirty data in their caches.  And OSDs know nothing
         * about caps, so they can't safely do the remote object copies.
         */
        err = get_rd_wr_caps(src_file, &src_got,
                             dst_file, (dst_off + len), &dst_got);
        if (err < 0) {
                dout("get_rd_wr_caps returned %d\n", err);
                ret = -EOPNOTSUPP;
                goto out;
        }

        ret = is_file_size_ok(src_inode, dst_inode, src_off, dst_off, len);
        if (ret < 0)
                goto out_caps;

        /* Drop dst file cached pages */
        ret = invalidate_inode_pages2_range(dst_inode->i_mapping,
                                            dst_off >> PAGE_SHIFT,
                                            (dst_off + len) >> PAGE_SHIFT);
        if (ret < 0) {
                dout("Failed to invalidate inode pages (%zd)\n", ret);
                ret = 0; /* XXX */
        }
        ceph_calc_file_object_mapping(&src_ci->i_layout, src_off,
                                      src_ci->i_layout.object_size,
                                      &src_objnum, &src_objoff, &src_objlen);
        ceph_calc_file_object_mapping(&dst_ci->i_layout, dst_off,
                                      dst_ci->i_layout.object_size,
                                      &dst_objnum, &dst_objoff, &dst_objlen);
        /* object-level offsets need to the same */
        if (src_objoff != dst_objoff) {
                ret = -EOPNOTSUPP;
                goto out_caps;
        }

        /*
         * Do a manual copy if the object offset isn't object aligned.
         * 'src_objlen' contains the bytes left until the end of the object,
         * starting at the src_off
         */
        if (src_objoff) {
                dout("Initial partial copy of %u bytes\n", src_objlen);

                /*
                 * we need to temporarily drop all caps as we'll be calling
                 * {read,write}_iter, which will get caps again.
                 */
                put_rd_wr_caps(src_ci, src_got, dst_ci, dst_got);
                ret = do_splice_direct(src_file, &src_off, dst_file,
                                       &dst_off, src_objlen, flags);
                /* Abort on short copies or on error */
                if (ret < src_objlen) {
                        dout("Failed partial copy (%zd)\n", ret);
                        goto out;
                }
                len -= ret;
                err = get_rd_wr_caps(src_file, &src_got,
                                     dst_file, (dst_off + len), &dst_got);
                if (err < 0)
                        goto out;
                err = is_file_size_ok(src_inode, dst_inode,
                                      src_off, dst_off, len);
                if (err < 0)
                        goto out_caps;
        }

        size = i_size_read(dst_inode);
        bytes = ceph_do_objects_copy(src_ci, &src_off, dst_ci, &dst_off,
                                     src_fsc, len, flags);
        if (bytes <= 0) {
                if (!ret)
                        ret = bytes;
                goto out_caps;
        }
        dout("Copied %zu bytes out of %zu\n", bytes, len);
        len -= bytes;
        ret += bytes;

        file_update_time(dst_file);
        inode_inc_iversion_raw(dst_inode);

        if (dst_off > size) {
                /* Let the MDS know about dst file size change */
                if (ceph_inode_set_size(dst_inode, dst_off) ||
                    ceph_quota_is_max_bytes_approaching(dst_inode, dst_off))
                        ceph_check_caps(dst_ci, CHECK_CAPS_AUTHONLY, NULL);
        }
        /* Mark Fw dirty */
        spin_lock(&dst_ci->i_ceph_lock);
        dst_ci->i_inline_version = CEPH_INLINE_NONE;
        dirty = __ceph_mark_dirty_caps(dst_ci, CEPH_CAP_FILE_WR, &prealloc_cf);
        spin_unlock(&dst_ci->i_ceph_lock);
        if (dirty)
                __mark_inode_dirty(dst_inode, dirty);

out_caps:
        put_rd_wr_caps(src_ci, src_got, dst_ci, dst_got);

        /*
         * Do the final manual copy if we still have some bytes left, unless
         * there were errors in remote object copies (len >= object_size).
         */
        if (len && (len < src_ci->i_layout.object_size)) {
                dout("Final partial copy of %zu bytes\n", len);
                bytes = do_splice_direct(src_file, &src_off, dst_file,
                                         &dst_off, len, flags);
                if (bytes > 0)
                        ret += bytes;
                else
                        dout("Failed partial copy (%zd)\n", bytes);
        }

out:
        ceph_free_cap_flush(prealloc_cf);

        return ret;
}

static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
                                    struct file *dst_file, loff_t dst_off,
                                    size_t len, unsigned int flags)
{
        ssize_t ret;

        ret = __ceph_copy_file_range(src_file, src_off, dst_file, dst_off,
                                     len, flags);

        if (ret == -EOPNOTSUPP || ret == -EXDEV)
                ret = generic_copy_file_range(src_file, src_off, dst_file,
                                              dst_off, len, flags);
        return ret;
}

const struct file_operations ceph_file_fops = {
        .open = ceph_open,
        .release = ceph_release,
        .llseek = ceph_llseek,
        .read_iter = ceph_read_iter,
        .write_iter = ceph_write_iter,
        .mmap = ceph_mmap,
        .fsync = ceph_fsync,
        .lock = ceph_lock,
        .setlease = simple_nosetlease,
        .flock = ceph_flock,
        .splice_read = generic_file_splice_read,
        .splice_write = iter_file_splice_write,
        .unlocked_ioctl = ceph_ioctl,
        .compat_ioctl = compat_ptr_ioctl,
        .fallocate      = ceph_fallocate,
        .copy_file_range = ceph_copy_file_range,
};