/*
 *  linux/fs/nfs/file.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 */
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/falloc.h>
#include <linux/nfs_fs.h>
#include <uapi/linux/btrfs.h>   /* BTRFS_IOC_CLONE/BTRFS_IOC_CLONE_RANGE */
#include "delegation.h"
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#include "pnfs.h"

#include "nfstrace.h"

#ifdef CONFIG_NFS_V4_2
#include "nfs42.h"
#endif

#define NFSDBG_FACILITY         NFSDBG_FILE

static int
nfs4_file_open(struct inode *inode, struct file *filp)
{
        struct nfs_open_context *ctx;
        struct dentry *dentry = filp->f_path.dentry;
        struct dentry *parent = NULL;
        struct inode *dir;
        unsigned openflags = filp->f_flags;
        struct iattr attr;
        int err;

        /*
         * If no cached dentry exists or if it's negative, NFSv4 handled the
         * opens in ->lookup() or ->create().
         *
         * We only get this far for a cached positive dentry.  We skipped
         * revalidation, so handle it here by dropping the dentry and returning
         * -EOPENSTALE.  The VFS will retry the lookup/create/open.
         */

        dprintk("NFS: open file(%pd2)\n", dentry);

        err = nfs_check_flags(openflags);
        if (err)
                return err;

        if ((openflags & O_ACCMODE) == 3)
                openflags--;

        /* We can't create new files here */
        openflags &= ~(O_CREAT|O_EXCL);

        parent = dget_parent(dentry);
        dir = d_inode(parent);

        ctx = alloc_nfs_open_context(filp->f_path.dentry, filp->f_mode);
        err = PTR_ERR(ctx);
        if (IS_ERR(ctx))
                goto out;

        attr.ia_valid = ATTR_OPEN;
        if (openflags & O_TRUNC) {
                attr.ia_valid |= ATTR_SIZE;
                attr.ia_size = 0;
                nfs_sync_inode(inode);
        }

        inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, &attr, NULL);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                switch (err) {
                case -EPERM:
                case -EACCES:
                case -EDQUOT:
                case -ENOSPC:
                case -EROFS:
                        goto out_put_ctx;
                default:
                        goto out_drop;
                }
        }
        if (inode != d_inode(dentry))
                goto out_drop;

        nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
        nfs_file_set_open_context(filp, ctx);
        nfs_fscache_open_file(inode, filp);
        err = 0;

out_put_ctx:
        put_nfs_open_context(ctx);
out:
        dput(parent);
        return err;

out_drop:
        d_drop(dentry);
        err = -EOPENSTALE;
        goto out_put_ctx;
}

/*
 * Flush all dirty pages, and check for write errors.
 */
static int
nfs4_file_flush(struct file *file, fl_owner_t id)
{
        struct inode    *inode = file_inode(file);

        dprintk("NFS: flush(%pD2)\n", file);

        nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
        if ((file->f_mode & FMODE_WRITE) == 0)
                return 0;

        /*
         * If we're holding a write delegation, then check if we're required
         * to flush the i/o on close. If not, then just start the i/o now.
         */
        if (!nfs4_delegation_flush_on_close(inode))
                return filemap_fdatawrite(file->f_mapping);

        /* Flush writes to the server and return any errors */
        return vfs_fsync(file, 0);
}

static int
nfs4_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
        int ret;
        struct inode *inode = file_inode(file);

        trace_nfs_fsync_enter(inode);

        nfs_inode_dio_wait(inode);
        do {
                ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
                if (ret != 0)
                        break;
                mutex_lock(&inode->i_mutex);
                ret = nfs_file_fsync_commit(file, start, end, datasync);
                if (!ret)
                        ret = pnfs_sync_inode(inode, !!datasync);
                mutex_unlock(&inode->i_mutex);
                /*
                 * If nfs_file_fsync_commit detected a server reboot, then
                 * resend all dirty pages that might have been covered by
                 * the NFS_CONTEXT_RESEND_WRITES flag
                 */
                start = 0;
                end = LLONG_MAX;
        } while (ret == -EAGAIN);

        trace_nfs_fsync_exit(inode, ret);
        return ret;
}

#ifdef CONFIG_NFS_V4_2
static loff_t nfs4_file_llseek(struct file *filep, loff_t offset, int whence)
{
        loff_t ret;

        switch (whence) {
        case SEEK_HOLE:
        case SEEK_DATA:
                ret = nfs42_proc_llseek(filep, offset, whence);
                if (ret != -ENOTSUPP)
                        return ret;
        default:
                return nfs_file_llseek(filep, offset, whence);
        }
}

static long nfs42_fallocate(struct file *filep, int mode, loff_t offset, loff_t len)
{
        struct inode *inode = file_inode(filep);
        long ret;

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

        if ((mode != 0) && (mode != (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE)))
                return -EOPNOTSUPP;

        ret = inode_newsize_ok(inode, offset + len);
        if (ret < 0)
                return ret;

        if (mode & FALLOC_FL_PUNCH_HOLE)
                return nfs42_proc_deallocate(filep, offset, len);
        return nfs42_proc_allocate(filep, offset, len);
}

static noinline long
nfs42_ioctl_clone(struct file *dst_file, unsigned long srcfd,
                  u64 src_off, u64 dst_off, u64 count)
{
        struct inode *dst_inode = file_inode(dst_file);
        struct nfs_server *server = NFS_SERVER(dst_inode);
        struct fd src_file;
        struct inode *src_inode;
        unsigned int bs = server->clone_blksize;
        bool same_inode = false;
        int ret;

        /* dst file must be opened for writing */
        if (!(dst_file->f_mode & FMODE_WRITE))
                return -EINVAL;

        ret = mnt_want_write_file(dst_file);
        if (ret)
                return ret;

        src_file = fdget(srcfd);
        if (!src_file.file) {
                ret = -EBADF;
                goto out_drop_write;
        }

        src_inode = file_inode(src_file.file);

        if (src_inode == dst_inode)
                same_inode = true;

        /* src file must be opened for reading */
        if (!(src_file.file->f_mode & FMODE_READ))
                goto out_fput;

        /* src and dst must be regular files */
        ret = -EISDIR;
        if (!S_ISREG(src_inode->i_mode) || !S_ISREG(dst_inode->i_mode))
                goto out_fput;

        ret = -EXDEV;
        if (src_file.file->f_path.mnt != dst_file->f_path.mnt ||
            src_inode->i_sb != dst_inode->i_sb)
                goto out_fput;

        /* check alignment w.r.t. clone_blksize */
        ret = -EINVAL;
        if (bs) {
                if (!IS_ALIGNED(src_off, bs) || !IS_ALIGNED(dst_off, bs))
                        goto out_fput;
                if (!IS_ALIGNED(count, bs) && i_size_read(src_inode) != (src_off + count))
                        goto out_fput;
        }

        /* verify if ranges are overlapped within the same file */
        if (same_inode) {
                if (dst_off + count > src_off && dst_off < src_off + count)
                        goto out_fput;
        }

        /* XXX: do we lock at all? what if server needs CB_RECALL_LAYOUT? */
        if (same_inode) {
                mutex_lock(&src_inode->i_mutex);
        } else if (dst_inode < src_inode) {
                mutex_lock_nested(&dst_inode->i_mutex, I_MUTEX_PARENT);
                mutex_lock_nested(&src_inode->i_mutex, I_MUTEX_CHILD);
        } else {
                mutex_lock_nested(&src_inode->i_mutex, I_MUTEX_PARENT);
                mutex_lock_nested(&dst_inode->i_mutex, I_MUTEX_CHILD);
        }

        /* flush all pending writes on both src and dst so that server
         * has the latest data */
        ret = nfs_sync_inode(src_inode);
        if (ret)
                goto out_unlock;
        ret = nfs_sync_inode(dst_inode);
        if (ret)
                goto out_unlock;

        ret = nfs42_proc_clone(src_file.file, dst_file, src_off, dst_off, count);

        /* truncate inode page cache of the dst range so that future reads can fetch
         * new data from server */
        if (!ret)
                truncate_inode_pages_range(&dst_inode->i_data, dst_off, dst_off + count - 1);

out_unlock:
        if (same_inode) {
                mutex_unlock(&src_inode->i_mutex);
        } else if (dst_inode < src_inode) {
                mutex_unlock(&src_inode->i_mutex);
                mutex_unlock(&dst_inode->i_mutex);
        } else {
                mutex_unlock(&dst_inode->i_mutex);
                mutex_unlock(&src_inode->i_mutex);
        }
out_fput:
        fdput(src_file);
out_drop_write:
        mnt_drop_write_file(dst_file);
        return ret;
}

static long nfs42_ioctl_clone_range(struct file *dst_file, void __user *argp)
{
        struct btrfs_ioctl_clone_range_args args;

        if (copy_from_user(&args, argp, sizeof(args)))
                return -EFAULT;

        return nfs42_ioctl_clone(dst_file, args.src_fd, args.src_offset,
                                 args.dest_offset, args.src_length);
}

long nfs4_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        void __user *argp = (void __user *)arg;

        switch (cmd) {
        case BTRFS_IOC_CLONE:
                return nfs42_ioctl_clone(file, arg, 0, 0, 0);
        case BTRFS_IOC_CLONE_RANGE:
                return nfs42_ioctl_clone_range(file, argp);
        }

        return -ENOTTY;
}
#endif /* CONFIG_NFS_V4_2 */

const struct file_operations nfs4_file_operations = {
        .read_iter      = nfs_file_read,
        .write_iter     = nfs_file_write,
        .mmap           = nfs_file_mmap,
        .open           = nfs4_file_open,
        .flush          = nfs4_file_flush,
        .release        = nfs_file_release,
        .fsync          = nfs4_file_fsync,
        .lock           = nfs_lock,
        .flock          = nfs_flock,
        .splice_read    = nfs_file_splice_read,
        .splice_write   = iter_file_splice_write,
        .check_flags    = nfs_check_flags,
        .setlease       = simple_nosetlease,
#ifdef CONFIG_NFS_V4_2
        .llseek         = nfs4_file_llseek,
        .fallocate      = nfs42_fallocate,
        .unlocked_ioctl = nfs4_ioctl,
        .compat_ioctl   = nfs4_ioctl,
#else
        .llseek         = nfs_file_llseek,
#endif
};