/*
 *  linux/fs/nfs/file.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 */
#include <linux/fs.h>
#include <linux/falloc.h>
#include <linux/nfs_fs.h>
#include "internal.h"
#include "fscache.h"
#include "pnfs.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 opened = 0;
        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);

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

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

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

        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_wb_all(inode);
        }

        inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, &attr, &opened);
        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 != dentry->d_inode)
                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;
}

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

        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_layoutcommit_inode(inode, true);
                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);

        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;

        mutex_lock(&inode->i_mutex);
        if (mode & FALLOC_FL_PUNCH_HOLE)
                ret = nfs42_proc_deallocate(filep, offset, len);
        else
                ret = nfs42_proc_allocate(filep, offset, len);
        mutex_unlock(&inode->i_mutex);

        nfs_zap_caches(inode);
        return ret;
}
#endif /* CONFIG_NFS_V4_2 */

const struct file_operations nfs4_file_operations = {
#ifdef CONFIG_NFS_V4_2
        .llseek         = nfs4_file_llseek,
#else
        .llseek         = nfs_file_llseek,
#endif
        .read           = new_sync_read,
        .write          = new_sync_write,
        .read_iter      = nfs_file_read,
        .write_iter     = nfs_file_write,
        .mmap           = nfs_file_mmap,
        .open           = nfs4_file_open,
        .flush          = nfs_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,
#ifdef CONFIG_NFS_V4_2
        .fallocate      = nfs42_fallocate,
#endif /* CONFIG_NFS_V4_2 */
        .check_flags    = nfs_check_flags,
        .setlease       = simple_nosetlease,
};