/*
 * (C) 2001 Clemson University and The University of Chicago
 *
 * See COPYING in top-level directory.
 */

/*
 *  Linux VFS file operations.
 */

#include "protocol.h"
#include "orangefs-kernel.h"
#include "orangefs-bufmap.h"
#include <linux/fs.h>
#include <linux/pagemap.h>

static int flush_racache(struct inode *inode)
{
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_kernel_op_s *new_op;
        int ret;

        gossip_debug(GOSSIP_UTILS_DEBUG,
            "%s: %pU: Handle is %pU | fs_id %d\n", __func__,
            get_khandle_from_ino(inode), &orangefs_inode->refn.khandle,
            orangefs_inode->refn.fs_id);

        new_op = op_alloc(ORANGEFS_VFS_OP_RA_FLUSH);
        if (!new_op)
                return -ENOMEM;
        new_op->upcall.req.ra_cache_flush.refn = orangefs_inode->refn;

        ret = service_operation(new_op, "orangefs_flush_racache",
            get_interruptible_flag(inode));

        gossip_debug(GOSSIP_UTILS_DEBUG, "%s: got return value of %d\n",
            __func__, ret);

        op_release(new_op);
        return ret;
}

/*
 * Copy to client-core's address space from the buffers specified
 * by the iovec upto total_size bytes.
 * NOTE: the iovector can either contain addresses which
 *       can futher be kernel-space or user-space addresses.
 *       or it can pointers to struct page's
 */
static int precopy_buffers(int buffer_index,
                           struct iov_iter *iter,
                           size_t total_size)
{
        int ret = 0;
        /*
         * copy data from application/kernel by pulling it out
         * of the iovec.
         */


        if (total_size) {
                ret = orangefs_bufmap_copy_from_iovec(iter,
                                                      buffer_index,
                                                      total_size);
                if (ret < 0)
                gossip_err("%s: Failed to copy-in buffers. Please make sure that the pvfs2-client is running. %ld\n",
                           __func__,
                           (long)ret);
        }

        if (ret < 0)
                gossip_err("%s: Failed to copy-in buffers. Please make sure that the pvfs2-client is running. %ld\n",
                        __func__,
                        (long)ret);
        return ret;
}

/*
 * Copy from client-core's address space to the buffers specified
 * by the iovec upto total_size bytes.
 * NOTE: the iovector can either contain addresses which
 *       can futher be kernel-space or user-space addresses.
 *       or it can pointers to struct page's
 */
static int postcopy_buffers(int buffer_index,
                            struct iov_iter *iter,
                            size_t total_size)
{
        int ret = 0;
        /*
         * copy data to application/kernel by pushing it out to
         * the iovec. NOTE; target buffers can be addresses or
         * struct page pointers.
         */
        if (total_size) {
                ret = orangefs_bufmap_copy_to_iovec(iter,
                                                    buffer_index,
                                                    total_size);
                if (ret < 0)
                        gossip_err("%s: Failed to copy-out buffers. Please make sure that the pvfs2-client is running (%ld)\n",
                                __func__,
                                (long)ret);
        }
        return ret;
}

/*
 * Post and wait for the I/O upcall to finish
 */
static ssize_t wait_for_direct_io(enum ORANGEFS_io_type type, struct inode *inode,
                loff_t *offset, struct iov_iter *iter,
                size_t total_size, loff_t readahead_size)
{
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_khandle *handle = &orangefs_inode->refn.khandle;
        struct orangefs_kernel_op_s *new_op = NULL;
        int buffer_index = -1;
        ssize_t ret;

        new_op = op_alloc(ORANGEFS_VFS_OP_FILE_IO);
        if (!new_op)
                return -ENOMEM;

        /* synchronous I/O */
        new_op->upcall.req.io.readahead_size = readahead_size;
        new_op->upcall.req.io.io_type = type;
        new_op->upcall.req.io.refn = orangefs_inode->refn;

populate_shared_memory:
        /* get a shared buffer index */
        buffer_index = orangefs_bufmap_get();
        if (buffer_index < 0) {
                ret = buffer_index;
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s: orangefs_bufmap_get failure (%zd)\n",
                             __func__, ret);
                goto out;
        }
        gossip_debug(GOSSIP_FILE_DEBUG,
                     "%s(%pU): GET op %p -> buffer_index %d\n",
                     __func__,
                     handle,
                     new_op,
                     buffer_index);

        new_op->uses_shared_memory = 1;
        new_op->upcall.req.io.buf_index = buffer_index;
        new_op->upcall.req.io.count = total_size;
        new_op->upcall.req.io.offset = *offset;

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "%s(%pU): offset: %llu total_size: %zd\n",
                     __func__,
                     handle,
                     llu(*offset),
                     total_size);
        /*
         * Stage 1: copy the buffers into client-core's address space
         * precopy_buffers only pertains to writes.
         */
        if (type == ORANGEFS_IO_WRITE) {
                ret = precopy_buffers(buffer_index,
                                      iter,
                                      total_size);
                if (ret < 0)
                        goto out;
        }

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "%s(%pU): Calling post_io_request with tag (%llu)\n",
                     __func__,
                     handle,
                     llu(new_op->tag));

        /* Stage 2: Service the I/O operation */
        ret = service_operation(new_op,
                                type == ORANGEFS_IO_WRITE ?
                                        "file_write" :
                                        "file_read",
                                get_interruptible_flag(inode));

        /*
         * If service_operation() returns -EAGAIN #and# the operation was
         * purged from orangefs_request_list or htable_ops_in_progress, then
         * we know that the client was restarted, causing the shared memory
         * area to be wiped clean.  To restart a  write operation in this
         * case, we must re-copy the data from the user's iovec to a NEW
         * shared memory location. To restart a read operation, we must get
         * a new shared memory location.
         */
        if (ret == -EAGAIN && op_state_purged(new_op)) {
                orangefs_bufmap_put(buffer_index);
                buffer_index = -1;
                if (type == ORANGEFS_IO_WRITE)
                        iov_iter_revert(iter, total_size);
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s:going to repopulate_shared_memory.\n",
                             __func__);
                goto populate_shared_memory;
        }

        if (ret < 0) {
                if (ret == -EINTR) {
                        /*
                         * We can't return EINTR if any data was written,
                         * it's not POSIX. It is minimally acceptable
                         * to give a partial write, the way NFS does.
                         *
                         * It would be optimal to return all or nothing,
                         * but if a userspace write is bigger than
                         * an IO buffer, and the interrupt occurs
                         * between buffer writes, that would not be
                         * possible.
                         */
                        switch (new_op->op_state - OP_VFS_STATE_GIVEN_UP) {
                        /*
                         * If the op was waiting when the interrupt
                         * occurred, then the client-core did not
                         * trigger the write.
                         */
                        case OP_VFS_STATE_WAITING:
                                if (*offset == 0)
                                        ret = -EINTR;
                                else
                                        ret = 0;
                                break;
                        /* 
                         * If the op was in progress when the interrupt
                         * occurred, then the client-core was able to
                         * trigger the write.
                         */
                        case OP_VFS_STATE_INPROGR:
                                ret = total_size;
                                break;
                        default:
                                gossip_err("%s: unexpected op state :%d:.\n",
                                           __func__,
                                           new_op->op_state);
                                ret = 0;
                                break;
                        }
                        gossip_debug(GOSSIP_FILE_DEBUG,
                                     "%s: got EINTR, state:%d: %p\n",
                                     __func__,
                                     new_op->op_state,
                                     new_op);
                } else {
                        gossip_err("%s: error in %s handle %pU, returning %zd\n",
                                __func__,
                                type == ORANGEFS_IO_READ ?
                                        "read from" : "write to",
                                handle, ret);
                }
                if (orangefs_cancel_op_in_progress(new_op))
                        return ret;

                goto out;
        }

        /*
         * Stage 3: Post copy buffers from client-core's address space
         * postcopy_buffers only pertains to reads.
         */
        if (type == ORANGEFS_IO_READ) {
                ret = postcopy_buffers(buffer_index,
                                       iter,
                                       new_op->downcall.resp.io.amt_complete);
                if (ret < 0)
                        goto out;
        }
        gossip_debug(GOSSIP_FILE_DEBUG,
            "%s(%pU): Amount %s, returned by the sys-io call:%d\n",
            __func__,
            handle,
            type == ORANGEFS_IO_READ ?  "read" : "written",
            (int)new_op->downcall.resp.io.amt_complete);

        ret = new_op->downcall.resp.io.amt_complete;

out:
        if (buffer_index >= 0) {
                orangefs_bufmap_put(buffer_index);
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s(%pU): PUT buffer_index %d\n",
                             __func__, handle, buffer_index);
                buffer_index = -1;
        }
        op_release(new_op);
        return ret;
}

/*
 * Common entry point for read/write/readv/writev
 * This function will dispatch it to either the direct I/O
 * or buffered I/O path depending on the mount options and/or
 * augmented/extended metadata attached to the file.
 * Note: File extended attributes override any mount options.
 */
static ssize_t do_readv_writev(enum ORANGEFS_io_type type, struct file *file,
                loff_t *offset, struct iov_iter *iter)
{
        struct inode *inode = file->f_mapping->host;
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_khandle *handle = &orangefs_inode->refn.khandle;
        size_t count = iov_iter_count(iter);
        ssize_t total_count = 0;
        ssize_t ret = -EINVAL;

        gossip_debug(GOSSIP_FILE_DEBUG,
                "%s-BEGIN(%pU): count(%d) after estimate_max_iovecs.\n",
                __func__,
                handle,
                (int)count);

        if (type == ORANGEFS_IO_WRITE) {
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s(%pU): proceeding with offset : %llu, "
                             "size %d\n",
                             __func__,
                             handle,
                             llu(*offset),
                             (int)count);
        }

        if (count == 0) {
                ret = 0;
                goto out;
        }

        while (iov_iter_count(iter)) {
                size_t each_count = iov_iter_count(iter);
                size_t amt_complete;

                /* how much to transfer in this loop iteration */
                if (each_count > orangefs_bufmap_size_query())
                        each_count = orangefs_bufmap_size_query();

                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s(%pU): size of each_count(%d)\n",
                             __func__,
                             handle,
                             (int)each_count);
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s(%pU): BEFORE wait_for_io: offset is %d\n",
                             __func__,
                             handle,
                             (int)*offset);

                ret = wait_for_direct_io(type, inode, offset, iter,
                                each_count, 0);
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s(%pU): return from wait_for_io:%d\n",
                             __func__,
                             handle,
                             (int)ret);

                if (ret < 0)
                        goto out;

                *offset += ret;
                total_count += ret;
                amt_complete = ret;

                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s(%pU): AFTER wait_for_io: offset is %d\n",
                             __func__,
                             handle,
                             (int)*offset);

                /*
                 * if we got a short I/O operations,
                 * fall out and return what we got so far
                 */
                if (amt_complete < each_count)
                        break;
        } /*end while */

out:
        if (total_count > 0)
                ret = total_count;
        if (ret > 0) {
                if (type == ORANGEFS_IO_READ) {
                        file_accessed(file);
                } else {
                        SetMtimeFlag(orangefs_inode);
                        inode->i_mtime = current_time(inode);
                        mark_inode_dirty_sync(inode);
                }
        }

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "%s(%pU): Value(%d) returned.\n",
                     __func__,
                     handle,
                     (int)ret);

        return ret;
}

/*
 * Read data from a specified offset in a file (referenced by inode).
 * Data may be placed either in a user or kernel buffer.
 */
ssize_t orangefs_inode_read(struct inode *inode,
                            struct iov_iter *iter,
                            loff_t *offset,
                            loff_t readahead_size)
{
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        size_t count = iov_iter_count(iter);
        size_t bufmap_size;
        ssize_t ret = -EINVAL;

        orangefs_stats.reads++;

        bufmap_size = orangefs_bufmap_size_query();
        if (count > bufmap_size) {
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "%s: count is too large (%zd/%zd)!\n",
                             __func__, count, bufmap_size);
                return -EINVAL;
        }

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "%s(%pU) %zd@%llu\n",
                     __func__,
                     &orangefs_inode->refn.khandle,
                     count,
                     llu(*offset));

        ret = wait_for_direct_io(ORANGEFS_IO_READ, inode, offset, iter,
                        count, readahead_size);
        if (ret > 0)
                *offset += ret;

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "%s(%pU): Value(%zd) returned.\n",
                     __func__,
                     &orangefs_inode->refn.khandle,
                     ret);

        return ret;
}

static ssize_t orangefs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
        struct file *file = iocb->ki_filp;
        loff_t pos = *(&iocb->ki_pos);
        ssize_t rc = 0;

        BUG_ON(iocb->private);

        gossip_debug(GOSSIP_FILE_DEBUG, "orangefs_file_read_iter\n");

        orangefs_stats.reads++;

        rc = do_readv_writev(ORANGEFS_IO_READ, file, &pos, iter);
        iocb->ki_pos = pos;

        return rc;
}

static ssize_t orangefs_file_write_iter(struct kiocb *iocb, struct iov_iter *iter)
{
        struct file *file = iocb->ki_filp;
        loff_t pos;
        ssize_t rc;

        BUG_ON(iocb->private);

        gossip_debug(GOSSIP_FILE_DEBUG, "orangefs_file_write_iter\n");

        inode_lock(file->f_mapping->host);

        /* Make sure generic_write_checks sees an up to date inode size. */
        if (file->f_flags & O_APPEND) {
                rc = orangefs_inode_getattr(file->f_mapping->host, 0, 1,
                    STATX_SIZE);
                if (rc == -ESTALE)
                        rc = -EIO;
                if (rc) {
                        gossip_err("%s: orangefs_inode_getattr failed, "
                            "rc:%zd:.\n", __func__, rc);
                        goto out;
                }
        }

        if (file->f_pos > i_size_read(file->f_mapping->host))
                orangefs_i_size_write(file->f_mapping->host, file->f_pos);

        rc = generic_write_checks(iocb, iter);

        if (rc <= 0) {
                gossip_err("%s: generic_write_checks failed, rc:%zd:.\n",
                           __func__, rc);
                goto out;
        }

        /*
         * if we are appending, generic_write_checks would have updated
         * pos to the end of the file, so we will wait till now to set
         * pos...
         */
        pos = *(&iocb->ki_pos);

        rc = do_readv_writev(ORANGEFS_IO_WRITE,
                             file,
                             &pos,
                             iter);
        if (rc < 0) {
                gossip_err("%s: do_readv_writev failed, rc:%zd:.\n",
                           __func__, rc);
                goto out;
        }

        iocb->ki_pos = pos;
        orangefs_stats.writes++;

out:

        inode_unlock(file->f_mapping->host);
        return rc;
}

/*
 * Perform a miscellaneous operation on a file.
 */
static long orangefs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        int ret = -ENOTTY;
        __u64 val = 0;
        unsigned long uval;

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "orangefs_ioctl: called with cmd %d\n",
                     cmd);

        /*
         * we understand some general ioctls on files, such as the immutable
         * and append flags
         */
        if (cmd == FS_IOC_GETFLAGS) {
                val = 0;
                ret = orangefs_inode_getxattr(file_inode(file),
                                              "user.pvfs2.meta_hint",
                                              &val, sizeof(val));
                if (ret < 0 && ret != -ENODATA)
                        return ret;
                else if (ret == -ENODATA)
                        val = 0;
                uval = val;
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "orangefs_ioctl: FS_IOC_GETFLAGS: %llu\n",
                             (unsigned long long)uval);
                return put_user(uval, (int __user *)arg);
        } else if (cmd == FS_IOC_SETFLAGS) {
                ret = 0;
                if (get_user(uval, (int __user *)arg))
                        return -EFAULT;
                /*
                 * ORANGEFS_MIRROR_FL is set internally when the mirroring mode
                 * is turned on for a file. The user is not allowed to turn
                 * on this bit, but the bit is present if the user first gets
                 * the flags and then updates the flags with some new
                 * settings. So, we ignore it in the following edit. bligon.
                 */
                if ((uval & ~ORANGEFS_MIRROR_FL) &
                    (~(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NOATIME_FL))) {
                        gossip_err("orangefs_ioctl: the FS_IOC_SETFLAGS only supports setting one of FS_IMMUTABLE_FL|FS_APPEND_FL|FS_NOATIME_FL\n");
                        return -EINVAL;
                }
                val = uval;
                gossip_debug(GOSSIP_FILE_DEBUG,
                             "orangefs_ioctl: FS_IOC_SETFLAGS: %llu\n",
                             (unsigned long long)val);
                ret = orangefs_inode_setxattr(file_inode(file),
                                              "user.pvfs2.meta_hint",
                                              &val, sizeof(val), 0);
        }

        return ret;
}

/*
 * Memory map a region of a file.
 */
static int orangefs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        gossip_debug(GOSSIP_FILE_DEBUG,
                     "orangefs_file_mmap: called on %s\n",
                     (file ?
                        (char *)file->f_path.dentry->d_name.name :
                        (char *)"Unknown"));

        /* set the sequential readahead hint */
        vma->vm_flags |= VM_SEQ_READ;
        vma->vm_flags &= ~VM_RAND_READ;

        /* Use readonly mmap since we cannot support writable maps. */
        return generic_file_readonly_mmap(file, vma);
}

#define mapping_nrpages(idata) ((idata)->nrpages)

/*
 * Called to notify the module that there are no more references to
 * this file (i.e. no processes have it open).
 *
 * \note Not called when each file is closed.
 */
static int orangefs_file_release(struct inode *inode, struct file *file)
{
        gossip_debug(GOSSIP_FILE_DEBUG,
                     "orangefs_file_release: called on %pD\n",
                     file);

        orangefs_flush_inode(inode);

        /*
         * remove all associated inode pages from the page cache and
         * readahead cache (if any); this forces an expensive refresh of
         * data for the next caller of mmap (or 'get_block' accesses)
         */
        if (file_inode(file) &&
            file_inode(file)->i_mapping &&
            mapping_nrpages(&file_inode(file)->i_data)) {
                if (orangefs_features & ORANGEFS_FEATURE_READAHEAD) {
                        gossip_debug(GOSSIP_INODE_DEBUG,
                            "calling flush_racache on %pU\n",
                            get_khandle_from_ino(inode));
                        flush_racache(inode);
                        gossip_debug(GOSSIP_INODE_DEBUG,
                            "flush_racache finished\n");
                }
                truncate_inode_pages(file_inode(file)->i_mapping,
                                     0);
        }
        return 0;
}

/*
 * Push all data for a specific file onto permanent storage.
 */
static int orangefs_fsync(struct file *file,
                       loff_t start,
                       loff_t end,
                       int datasync)
{
        int ret = -EINVAL;
        struct orangefs_inode_s *orangefs_inode =
                ORANGEFS_I(file_inode(file));
        struct orangefs_kernel_op_s *new_op = NULL;

        /* required call */
        filemap_write_and_wait_range(file->f_mapping, start, end);

        new_op = op_alloc(ORANGEFS_VFS_OP_FSYNC);
        if (!new_op)
                return -ENOMEM;
        new_op->upcall.req.fsync.refn = orangefs_inode->refn;

        ret = service_operation(new_op,
                        "orangefs_fsync",
                        get_interruptible_flag(file_inode(file)));

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "orangefs_fsync got return value of %d\n",
                     ret);

        op_release(new_op);

        orangefs_flush_inode(file_inode(file));
        return ret;
}

/*
 * Change the file pointer position for an instance of an open file.
 *
 * \note If .llseek is overriden, we must acquire lock as described in
 *       Documentation/filesystems/Locking.
 *
 * Future upgrade could support SEEK_DATA and SEEK_HOLE but would
 * require much changes to the FS
 */
static loff_t orangefs_file_llseek(struct file *file, loff_t offset, int origin)
{
        int ret = -EINVAL;
        struct inode *inode = file_inode(file);

        if (origin == SEEK_END) {
                /*
                 * revalidate the inode's file size.
                 * NOTE: We are only interested in file size here,
                 * so we set mask accordingly.
                 */
                ret = orangefs_inode_getattr(file->f_mapping->host, 0, 1,
                    STATX_SIZE);
                if (ret == -ESTALE)
                        ret = -EIO;
                if (ret) {
                        gossip_debug(GOSSIP_FILE_DEBUG,
                                     "%s:%s:%d calling make bad inode\n",
                                     __FILE__,
                                     __func__,
                                     __LINE__);
                        return ret;
                }
        }

        gossip_debug(GOSSIP_FILE_DEBUG,
                     "orangefs_file_llseek: offset is %ld | origin is %d"
                     " | inode size is %lu\n",
                     (long)offset,
                     origin,
                     (unsigned long)i_size_read(inode));

        return generic_file_llseek(file, offset, origin);
}

/*
 * Support local locks (locks that only this kernel knows about)
 * if Orangefs was mounted -o local_lock.
 */
static int orangefs_lock(struct file *filp, int cmd, struct file_lock *fl)
{
        int rc = -EINVAL;

        if (ORANGEFS_SB(file_inode(filp)->i_sb)->flags & ORANGEFS_OPT_LOCAL_LOCK) {
                if (cmd == F_GETLK) {
                        rc = 0;
                        posix_test_lock(filp, fl);
                } else {
                        rc = posix_lock_file(filp, fl, NULL);
                }
        }

        return rc;
}

/** ORANGEFS implementation of VFS file operations */
const struct file_operations orangefs_file_operations = {
        .llseek         = orangefs_file_llseek,
        .read_iter      = orangefs_file_read_iter,
        .write_iter     = orangefs_file_write_iter,
        .lock           = orangefs_lock,
        .unlocked_ioctl = orangefs_ioctl,
        .mmap           = orangefs_file_mmap,
        .open           = generic_file_open,
        .release        = orangefs_file_release,
        .fsync          = orangefs_fsync,
};