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

/*
 *  Linux VFS file operations.
 */

#include "protocol.h"
#include "pvfs2-kernel.h"
#include "pvfs2-bufmap.h"
#include <linux/fs.h>
#include <linux/pagemap.h>

#define wake_up_daemon_for_return(op)			\
do {							\
	spin_lock(&op->lock);                           \
	op->io_completed = 1;                           \
	spin_unlock(&op->lock);                         \
	wake_up_interruptible(&op->io_completion_waitq);\
} while (0)

/*
 * 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(struct pvfs2_bufmap *bufmap,
			   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 = pvfs_bufmap_copy_from_iovec(bufmap,
						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(struct pvfs2_bufmap *bufmap,
			    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 = pvfs_bufmap_copy_to_iovec(bufmap,
						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 PVFS_io_type type, struct inode *inode,
		loff_t *offset, struct iov_iter *iter,
		size_t total_size, loff_t readahead_size)
{
	struct pvfs2_inode_s *pvfs2_inode = PVFS2_I(inode);
	struct pvfs2_khandle *handle = &pvfs2_inode->refn.khandle;
	struct pvfs2_bufmap *bufmap = NULL;
	struct pvfs2_kernel_op_s *new_op = NULL;
	int buffer_index = -1;
	ssize_t ret;

	new_op = op_alloc(PVFS2_VFS_OP_FILE_IO);
	if (!new_op) {
		ret = -ENOMEM;
		goto out;
	}
	/* synchronous I/O */
	new_op->upcall.req.io.async_vfs_io = PVFS_VFS_SYNC_IO;
	new_op->upcall.req.io.readahead_size = readahead_size;
	new_op->upcall.req.io.io_type = type;
	new_op->upcall.req.io.refn = pvfs2_inode->refn;

populate_shared_memory:
	/* get a shared buffer index */
	ret = pvfs_bufmap_get(&bufmap, &buffer_index);
	if (ret < 0) {
		gossip_debug(GOSSIP_FILE_DEBUG,
			     "%s: pvfs_bufmap_get failure (%ld)\n",
			     __func__, (long)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 == PVFS_IO_WRITE) {
		ret = precopy_buffers(bufmap,
				      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 == PVFS_IO_WRITE ?
					"file_write" :
					"file_read",
				get_interruptible_flag(inode));

	/*
	 * If service_operation() returns -EAGAIN #and# the operation was
	 * purged from pvfs2_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)) {
		pvfs_bufmap_put(bufmap, buffer_index);
		gossip_debug(GOSSIP_FILE_DEBUG,
			     "%s:going to repopulate_shared_memory.\n",
			     __func__);
		goto populate_shared_memory;
	}

	if (ret < 0) {
		handle_io_error(); /* defined in pvfs2-kernel.h */
		/*
		 * don't write an error to syslog on signaled operation
		 * termination unless we've got debugging turned on, as
		 * this can happen regularly (i.e. ctrl-c)
		 */
		if (ret == -EINTR)
			gossip_debug(GOSSIP_FILE_DEBUG,
				     "%s: returning error %ld\n", __func__,
				     (long)ret);
		else
			gossip_err("%s: error in %s handle %pU, returning %zd\n",
				__func__,
				type == PVFS_IO_READ ?
					"read from" : "write to",
				handle, ret);
		goto out;
	}

	/*
	 * Stage 3: Post copy buffers from client-core's address space
	 * postcopy_buffers only pertains to reads.
	 */
	if (type == PVFS_IO_READ) {
		ret = postcopy_buffers(bufmap,
				       buffer_index,
				       iter,
				       new_op->downcall.resp.io.amt_complete);
		if (ret < 0) {
			/*
			 * put error codes in downcall so that handle_io_error()
			 * preserves it properly
			 */
			new_op->downcall.status = ret;
			handle_io_error();
			goto out;
		}
	}
	gossip_debug(GOSSIP_FILE_DEBUG,
	    "%s(%pU): Amount written as returned by the sys-io call:%d\n",
	    __func__,
	    handle,
	    (int)new_op->downcall.resp.io.amt_complete);

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

	/*
	 * tell the device file owner waiting on I/O that this read has
	 * completed and it can return now.  in this exact case, on
	 * wakeup the daemon will free the op, so we *cannot* touch it
	 * after this.
	 */
	wake_up_daemon_for_return(new_op);
	new_op = NULL;

out:
	if (buffer_index >= 0) {
		pvfs_bufmap_put(bufmap, buffer_index);
		gossip_debug(GOSSIP_FILE_DEBUG,
			     "%s(%pU): PUT buffer_index %d\n",
			     __func__, handle, buffer_index);
		buffer_index = -1;
	}
	if (new_op) {
		op_release(new_op);
		new_op = NULL;
	}
	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 PVFS_io_type type, struct file *file,
		loff_t *offset, struct iov_iter *iter)
{
	struct inode *inode = file->f_mapping->host;
	struct pvfs2_inode_s *pvfs2_inode = PVFS2_I(inode);
	struct pvfs2_khandle *handle = &pvfs2_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 == PVFS_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 > pvfs_bufmap_size_query())
			each_count = pvfs_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 */

	if (total_count > 0)
		ret = total_count;
out:
	if (ret > 0) {
		if (type == PVFS_IO_READ) {
			file_accessed(file);
		} else {
			SetMtimeFlag(pvfs2_inode);
			inode->i_mtime = CURRENT_TIME;
			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 pvfs2_inode_read(struct inode *inode,
			 struct iov_iter *iter,
			 loff_t *offset,
			 loff_t readahead_size)
{
	struct pvfs2_inode_s *pvfs2_inode = PVFS2_I(inode);
	size_t count = iov_iter_count(iter);
	size_t bufmap_size;
	ssize_t ret = -EINVAL;

	g_pvfs2_stats.reads++;

	bufmap_size = pvfs_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__,
		     &pvfs2_inode->refn.khandle,
		     count,
		     llu(*offset));

	ret = wait_for_direct_io(PVFS_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__,
		     &pvfs2_inode->refn.khandle,
		     ret);

	return ret;
}

static ssize_t pvfs2_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, "pvfs2_file_read_iter\n");

	g_pvfs2_stats.reads++;

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

	return rc;
}

static ssize_t pvfs2_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, "pvfs2_file_write_iter\n");

	mutex_lock(&file->f_mapping->host->i_mutex);

	/* Make sure generic_write_checks sees an up to date inode size. */
	if (file->f_flags & O_APPEND) {
		rc = pvfs2_inode_getattr(file->f_mapping->host,
					 PVFS_ATTR_SYS_SIZE);
		if (rc) {
			gossip_err("%s: pvfs2_inode_getattr failed, rc:%zd:.\n",
				   __func__, rc);
			goto out;
		}
	}

	if (file->f_pos > i_size_read(file->f_mapping->host))
		pvfs2_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(PVFS_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;
	g_pvfs2_stats.writes++;

out:

	mutex_unlock(&file->f_mapping->host->i_mutex);
	return rc;
}

/*
 * Perform a miscellaneous operation on a file.
 */
static long pvfs2_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	int ret = -ENOTTY;
	__u64 val = 0;
	unsigned long uval;

	gossip_debug(GOSSIP_FILE_DEBUG,
		     "pvfs2_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 = pvfs2_xattr_get_default(file->f_path.dentry,
					      "user.pvfs2.meta_hint",
					      &val,
					      sizeof(val),
					      0);
		if (ret < 0 && ret != -ENODATA)
			return ret;
		else if (ret == -ENODATA)
			val = 0;
		uval = val;
		gossip_debug(GOSSIP_FILE_DEBUG,
			     "pvfs2_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;
		/*
		 * PVFS_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 & ~PVFS_MIRROR_FL) &
		    (~(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NOATIME_FL))) {
			gossip_err("pvfs2_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,
			     "pvfs2_ioctl: FS_IOC_SETFLAGS: %llu\n",
			     (unsigned long long)val);
		ret = pvfs2_xattr_set_default(file->f_path.dentry,
					      "user.pvfs2.meta_hint",
					      &val,
					      sizeof(val),
					      0,
					      0);
	}

	return ret;
}

/*
 * Memory map a region of a file.
 */
static int pvfs2_file_mmap(struct file *file, struct vm_area_struct *vma)
{
	gossip_debug(GOSSIP_FILE_DEBUG,
		     "pvfs2_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 pvfs2_file_release(struct inode *inode, struct file *file)
{
	gossip_debug(GOSSIP_FILE_DEBUG,
		     "pvfs2_file_release: called on %s\n",
		     file->f_path.dentry->d_name.name);

	pvfs2_flush_inode(inode);

	/*
	 * remove all associated inode pages from the page cache and mmap
	 * readahead cache (if any); this forces an expensive refresh of
	 * data for the next caller of mmap (or 'get_block' accesses)
	 */
	if (file->f_path.dentry->d_inode &&
	    file->f_path.dentry->d_inode->i_mapping &&
	    mapping_nrpages(&file->f_path.dentry->d_inode->i_data))
		truncate_inode_pages(file->f_path.dentry->d_inode->i_mapping,
				     0);
	return 0;
}

/*
 * Push all data for a specific file onto permanent storage.
 */
static int pvfs2_fsync(struct file *file,
		       loff_t start,
		       loff_t end,
		       int datasync)
{
	int ret = -EINVAL;
	struct pvfs2_inode_s *pvfs2_inode =
		PVFS2_I(file->f_path.dentry->d_inode);
	struct pvfs2_kernel_op_s *new_op = NULL;

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

	new_op = op_alloc(PVFS2_VFS_OP_FSYNC);
	if (!new_op)
		return -ENOMEM;
	new_op->upcall.req.fsync.refn = pvfs2_inode->refn;

	ret = service_operation(new_op,
			"pvfs2_fsync",
			get_interruptible_flag(file->f_path.dentry->d_inode));

	gossip_debug(GOSSIP_FILE_DEBUG,
		     "pvfs2_fsync got return value of %d\n",
		     ret);

	op_release(new_op);

	pvfs2_flush_inode(file->f_path.dentry->d_inode);
	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 pvfs2_file_llseek(struct file *file, loff_t offset, int origin)
{
	int ret = -EINVAL;
	struct inode *inode = file->f_path.dentry->d_inode;

	if (!inode) {
		gossip_err("pvfs2_file_llseek: invalid inode (NULL)\n");
		return ret;
	}

	if (origin == PVFS2_SEEK_END) {
		/*
		 * revalidate the inode's file size.
		 * NOTE: We are only interested in file size here,
		 * so we set mask accordingly.
		 */
		ret = pvfs2_inode_getattr(inode, PVFS_ATTR_SYS_SIZE);
		if (ret) {
			gossip_debug(GOSSIP_FILE_DEBUG,
				     "%s:%s:%d calling make bad inode\n",
				     __FILE__,
				     __func__,
				     __LINE__);
			pvfs2_make_bad_inode(inode);
			return ret;
		}
	}

	gossip_debug(GOSSIP_FILE_DEBUG,
		     "pvfs2_file_llseek: offset is %ld | origin is %d"
		     " | inode size is %lu\n",
		     (long)offset,
		     origin,
		     (unsigned long)file->f_path.dentry->d_inode->i_size);

	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 pvfs2_lock(struct file *filp, int cmd, struct file_lock *fl)
{
	int rc = -EINVAL;

	if (PVFS2_SB(filp->f_inode->i_sb)->flags & PVFS2_OPT_LOCAL_LOCK) {
		if (cmd == F_GETLK) {
			rc = 0;
			posix_test_lock(filp, fl);
		} else {
			rc = posix_lock_file(filp, fl, NULL);
		}
	}

	return rc;
}

/** PVFS2 implementation of VFS file operations */
const struct file_operations pvfs2_file_operations = {
	.llseek		= pvfs2_file_llseek,
	.read_iter	= pvfs2_file_read_iter,
	.write_iter	= pvfs2_file_write_iter,
	.lock		= pvfs2_lock,
	.unlocked_ioctl	= pvfs2_ioctl,
	.mmap		= pvfs2_file_mmap,
	.open		= generic_file_open,
	.release	= pvfs2_file_release,
	.fsync		= pvfs2_fsync,
};