fs/9p/vfs_file.c - kernel/msm-4.9 - Gitiles

 /*
  *  linux/fs/9p/vfs_file.c
  *
  * This file contians vfs file ops for 9P2000.
  *
  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to:
  *  Free Software Foundation
  *  51 Franklin Street, Fifth Floor
  *  Boston, MA  02111-1301  USA
  *
  */

 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include <linux/file.h>
 #include <linux/stat.h>
 #include <linux/string.h>
 #include <linux/inet.h>
 #include <linux/list.h>
 #include <linux/pagemap.h>
 #include <linux/utsname.h>
 #include <asm/uaccess.h>
 #include <linux/idr.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>

 #include "v9fs.h"
 #include "v9fs_vfs.h"
 #include "fid.h"
 #include "cache.h"

 static const struct vm_operations_struct v9fs_file_vm_ops;

 /**
  * v9fs_file_open - open a file (or directory)
  * @inode: inode to be opened
  * @file: file being opened
  *
  */

 int v9fs_file_open(struct inode *inode, struct file *file)
 {
 	int err;
 	struct v9fs_inode *v9inode;
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid;
 	int omode;

 	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
 	v9inode = V9FS_I(inode);
 	v9ses = v9fs_inode2v9ses(inode);
 	if (v9fs_proto_dotl(v9ses))
 		omode = v9fs_open_to_dotl_flags(file->f_flags);
 	else
 		omode = v9fs_uflags2omode(file->f_flags,
 					v9fs_proto_dotu(v9ses));
 	fid = file->private_data;
 	if (!fid) {
 		fid = v9fs_fid_clone(file->f_path.dentry);
 		if (IS_ERR(fid))
 			return PTR_ERR(fid);

 		err = p9_client_open(fid, omode);
 		if (err < 0) {
 			p9_client_clunk(fid);
 			return err;
 		}
 		if (file->f_flags & O_TRUNC) {
 			i_size_write(inode, 0);
 			inode->i_blocks = 0;
 		}
 		if ((file->f_flags & O_APPEND) &&
 			(!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
 			generic_file_llseek(file, 0, SEEK_END);
 	}

 	file->private_data = fid;
 	mutex_lock(&v9inode->v_mutex);
 	if (v9ses->cache && !v9inode->writeback_fid &&
 	    ((file->f_flags & O_ACCMODE) != O_RDONLY)) {
 		/*
 		 * clone a fid and add it to writeback_fid
 		 * we do it during open time instead of
 		 * page dirty time via write_begin/page_mkwrite
 		 * because we want write after unlink usecase
 		 * to work.
 		 */
 		fid = v9fs_writeback_fid(file->f_path.dentry);
 		if (IS_ERR(fid)) {
 			err = PTR_ERR(fid);
 			mutex_unlock(&v9inode->v_mutex);
 			goto out_error;
 		}
 		v9inode->writeback_fid = (void *) fid;
 	}
 	mutex_unlock(&v9inode->v_mutex);
 #ifdef CONFIG_9P_FSCACHE
 	if (v9ses->cache)
 		v9fs_cache_inode_set_cookie(inode, file);
 #endif
 	return 0;
 out_error:
 	p9_client_clunk(file->private_data);
 	file->private_data = NULL;
 	return err;
 }

 /**
  * v9fs_file_lock - lock a file (or directory)
  * @filp: file to be locked
  * @cmd: lock command
  * @fl: file lock structure
  *
  * Bugs: this looks like a local only lock, we should extend into 9P
  *       by using open exclusive
  */

 static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
 {
 	int res = 0;
 	struct inode *inode = filp->f_path.dentry->d_inode;

 	p9_debug(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);

 	/* No mandatory locks */
 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
 		return -ENOLCK;

 	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
 		filemap_write_and_wait(inode->i_mapping);
 		invalidate_mapping_pages(&inode->i_data, 0, -1);
 	}

 	return res;
 }

 static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
 {
 	struct p9_flock flock;
 	struct p9_fid *fid;
 	uint8_t status;
 	int res = 0;
 	unsigned char fl_type;

 	fid = filp->private_data;
 	BUG_ON(fid == NULL);

 	if ((fl->fl_flags & FL_POSIX) != FL_POSIX)
 		BUG();

 	res = posix_lock_file_wait(filp, fl);
 	if (res < 0)
 		goto out;

 	/* convert posix lock to p9 tlock args */
 	memset(&flock, 0, sizeof(flock));
 	/* map the lock type */
 	switch (fl->fl_type) {
 	case F_RDLCK:
 		flock.type = P9_LOCK_TYPE_RDLCK;
 		break;
 	case F_WRLCK:
 		flock.type = P9_LOCK_TYPE_WRLCK;
 		break;
 	case F_UNLCK:
 		flock.type = P9_LOCK_TYPE_UNLCK;
 		break;
 	}
 	flock.start = fl->fl_start;
 	if (fl->fl_end == OFFSET_MAX)
 		flock.length = 0;
 	else
 		flock.length = fl->fl_end - fl->fl_start + 1;
 	flock.proc_id = fl->fl_pid;
 	flock.client_id = utsname()->nodename;
 	if (IS_SETLKW(cmd))
 		flock.flags = P9_LOCK_FLAGS_BLOCK;

 	/*
 	 * if its a blocked request and we get P9_LOCK_BLOCKED as the status
 	 * for lock request, keep on trying
 	 */
 	for (;;) {
 		res = p9_client_lock_dotl(fid, &flock, &status);
 		if (res < 0)
 			break;

 		if (status != P9_LOCK_BLOCKED)
 			break;
 		if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
 			break;
 		if (schedule_timeout_interruptible(P9_LOCK_TIMEOUT) != 0)
 			break;
 	}

 	/* map 9p status to VFS status */
 	switch (status) {
 	case P9_LOCK_SUCCESS:
 		res = 0;
 		break;
 	case P9_LOCK_BLOCKED:
 		res = -EAGAIN;
 		break;
 	case P9_LOCK_ERROR:
 	case P9_LOCK_GRACE:
 		res = -ENOLCK;
 		break;
 	default:
 		BUG();
 	}

 	/*
 	 * incase server returned error for lock request, revert
 	 * it locally
 	 */
 	if (res < 0 && fl->fl_type != F_UNLCK) {
 		fl_type = fl->fl_type;
 		fl->fl_type = F_UNLCK;
 		res = posix_lock_file_wait(filp, fl);
 		fl->fl_type = fl_type;
 	}
 out:
 	return res;
 }

 static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
 {
 	struct p9_getlock glock;
 	struct p9_fid *fid;
 	int res = 0;

 	fid = filp->private_data;
 	BUG_ON(fid == NULL);

 	posix_test_lock(filp, fl);
 	/*
 	 * if we have a conflicting lock locally, no need to validate
 	 * with server
 	 */
 	if (fl->fl_type != F_UNLCK)
 		return res;

 	/* convert posix lock to p9 tgetlock args */
 	memset(&glock, 0, sizeof(glock));
 	glock.type  = P9_LOCK_TYPE_UNLCK;
 	glock.start = fl->fl_start;
 	if (fl->fl_end == OFFSET_MAX)
 		glock.length = 0;
 	else
 		glock.length = fl->fl_end - fl->fl_start + 1;
 	glock.proc_id = fl->fl_pid;
 	glock.client_id = utsname()->nodename;

 	res = p9_client_getlock_dotl(fid, &glock);
 	if (res < 0)
 		return res;
 	/* map 9p lock type to os lock type */
 	switch (glock.type) {
 	case P9_LOCK_TYPE_RDLCK:
 		fl->fl_type = F_RDLCK;
 		break;
 	case P9_LOCK_TYPE_WRLCK:
 		fl->fl_type = F_WRLCK;
 		break;
 	case P9_LOCK_TYPE_UNLCK:
 		fl->fl_type = F_UNLCK;
 		break;
 	}
 	if (glock.type != P9_LOCK_TYPE_UNLCK) {
 		fl->fl_start = glock.start;
 		if (glock.length == 0)
 			fl->fl_end = OFFSET_MAX;
 		else
 			fl->fl_end = glock.start + glock.length - 1;
 		fl->fl_pid = glock.proc_id;
 	}
 	return res;
 }

 /**
  * v9fs_file_lock_dotl - lock a file (or directory)
  * @filp: file to be locked
  * @cmd: lock command
  * @fl: file lock structure
  *
  */

 static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
 {
 	struct inode *inode = filp->f_path.dentry->d_inode;
 	int ret = -ENOLCK;

 	p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n",
 		 filp, cmd, fl, filp->f_path.dentry->d_name.name);

 	/* No mandatory locks */
 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
 		goto out_err;

 	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
 		filemap_write_and_wait(inode->i_mapping);
 		invalidate_mapping_pages(&inode->i_data, 0, -1);
 	}

 	if (IS_SETLK(cmd) || IS_SETLKW(cmd))
 		ret = v9fs_file_do_lock(filp, cmd, fl);
 	else if (IS_GETLK(cmd))
 		ret = v9fs_file_getlock(filp, fl);
 	else
 		ret = -EINVAL;
 out_err:
 	return ret;
 }

 /**
  * v9fs_file_flock_dotl - lock a file
  * @filp: file to be locked
  * @cmd: lock command
  * @fl: file lock structure
  *
  */

 static int v9fs_file_flock_dotl(struct file *filp, int cmd,
 	struct file_lock *fl)
 {
 	struct inode *inode = filp->f_path.dentry->d_inode;
 	int ret = -ENOLCK;

 	p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n",
 		 filp, cmd, fl, filp->f_path.dentry->d_name.name);

 	/* No mandatory locks */
 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
 		goto out_err;

 	if (!(fl->fl_flags & FL_FLOCK))
 		goto out_err;

 	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
 		filemap_write_and_wait(inode->i_mapping);
 		invalidate_mapping_pages(&inode->i_data, 0, -1);
 	}
 	/* Convert flock to posix lock */
 	fl->fl_owner = (fl_owner_t)filp;
 	fl->fl_start = 0;
 	fl->fl_end = OFFSET_MAX;
 	fl->fl_flags |= FL_POSIX;
 	fl->fl_flags ^= FL_FLOCK;

 	if (IS_SETLK(cmd) | IS_SETLKW(cmd))
 		ret = v9fs_file_do_lock(filp, cmd, fl);
 	else
 		ret = -EINVAL;
 out_err:
 	return ret;
 }

 /**
  * v9fs_fid_readn - read from a fid
  * @fid: fid to read
  * @data: data buffer to read data into
  * @udata: user data buffer to read data into
  * @count: size of buffer
  * @offset: offset at which to read data
  *
  */
 ssize_t
 v9fs_fid_readn(struct p9_fid *fid, char *data, char __user *udata, u32 count,
 	       u64 offset)
 {
 	int n, total, size;

 	p9_debug(P9_DEBUG_VFS, "fid %d offset %llu count %d\n",
 		 fid->fid, (long long unsigned)offset, count);
 	n = 0;
 	total = 0;
 	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
 	do {
 		n = p9_client_read(fid, data, udata, offset, count);
 		if (n <= 0)
 			break;

 		if (data)
 			data += n;
 		if (udata)
 			udata += n;

 		offset += n;
 		count -= n;
 		total += n;
 	} while (count > 0 && n == size);

 	if (n < 0)
 		total = n;

 	return total;
 }

 /**
  * v9fs_file_readn - read from a file
  * @filp: file pointer to read
  * @data: data buffer to read data into
  * @udata: user data buffer to read data into
  * @count: size of buffer
  * @offset: offset at which to read data
  *
  */
 ssize_t
 v9fs_file_readn(struct file *filp, char *data, char __user *udata, u32 count,
 	       u64 offset)
 {
 	return v9fs_fid_readn(filp->private_data, data, udata, count, offset);
 }

 /**
  * v9fs_file_read - read from a file
  * @filp: file pointer to read
  * @udata: user data buffer to read data into
  * @count: size of buffer
  * @offset: offset at which to read data
  *
  */

 static ssize_t
 v9fs_file_read(struct file *filp, char __user *udata, size_t count,
 	       loff_t * offset)
 {
 	int ret;
 	struct p9_fid *fid;
 	size_t size;

 	p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n", count, *offset);
 	fid = filp->private_data;

 	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
 	if (count > size)
 		ret = v9fs_file_readn(filp, NULL, udata, count, *offset);
 	else
 		ret = p9_client_read(fid, NULL, udata, *offset, count);

 	if (ret > 0)
 		*offset += ret;

 	return ret;
 }

 ssize_t
 v9fs_file_write_internal(struct inode *inode, struct p9_fid *fid,
 			 const char __user *data, size_t count,
 			 loff_t *offset, int invalidate)
 {
 	int n;
 	loff_t i_size;
 	size_t total = 0;
 	struct p9_client *clnt;
 	loff_t origin = *offset;
 	unsigned long pg_start, pg_end;

 	p9_debug(P9_DEBUG_VFS, "data %p count %d offset %x\n",
 		 data, (int)count, (int)*offset);

 	clnt = fid->clnt;
 	do {
 		n = p9_client_write(fid, NULL, data+total, origin+total, count);
 		if (n <= 0)
 			break;
 		count -= n;
 		total += n;
 	} while (count > 0);

 	if (invalidate && (total > 0)) {
 		pg_start = origin >> PAGE_CACHE_SHIFT;
 		pg_end = (origin + total - 1) >> PAGE_CACHE_SHIFT;
 		if (inode->i_mapping && inode->i_mapping->nrpages)
 			invalidate_inode_pages2_range(inode->i_mapping,
 						      pg_start, pg_end);
 		*offset += total;
 		i_size = i_size_read(inode);
 		if (*offset > i_size) {
 			inode_add_bytes(inode, *offset - i_size);
 			i_size_write(inode, *offset);
 		}
 	}
 	if (n < 0)
 		return n;

 	return total;
 }

 /**
  * v9fs_file_write - write to a file
  * @filp: file pointer to write
  * @data: data buffer to write data from
  * @count: size of buffer
  * @offset: offset at which to write data
  *
  */
 static ssize_t
 v9fs_file_write(struct file *filp, const char __user * data,
 		size_t count, loff_t *offset)
 {
 	ssize_t retval = 0;
 	loff_t origin = *offset;


 	retval = generic_write_checks(filp, &origin, &count, 0);
 	if (retval)
 		goto out;

 	retval = -EINVAL;
 	if ((ssize_t) count < 0)
 		goto out;
 	retval = 0;
 	if (!count)
 		goto out;

 	retval = v9fs_file_write_internal(filp->f_path.dentry->d_inode,
 					filp->private_data,
 					data, count, &origin, 1);
 	/* update offset on successful write */
 	if (retval > 0)
 		*offset = origin;
 out:
 	return retval;
 }


 static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
 			   int datasync)
 {
 	struct p9_fid *fid;
 	struct inode *inode = filp->f_mapping->host;
 	struct p9_wstat wstat;
 	int retval;

 	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
 	if (retval)
 		return retval;

 	mutex_lock(&inode->i_mutex);
 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);

 	fid = filp->private_data;
 	v9fs_blank_wstat(&wstat);

 	retval = p9_client_wstat(fid, &wstat);
 	mutex_unlock(&inode->i_mutex);

 	return retval;
 }

 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
 			 int datasync)
 {
 	struct p9_fid *fid;
 	struct inode *inode = filp->f_mapping->host;
 	int retval;

 	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
 	if (retval)
 		return retval;

 	mutex_lock(&inode->i_mutex);
 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);

 	fid = filp->private_data;

 	retval = p9_client_fsync(fid, datasync);
 	mutex_unlock(&inode->i_mutex);

 	return retval;
 }

 static int
 v9fs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	int retval;

 	retval = generic_file_mmap(file, vma);
 	if (!retval)
 		vma->vm_ops = &v9fs_file_vm_ops;

 	return retval;
 }

 static int
 v9fs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct v9fs_inode *v9inode;
 	struct page *page = vmf->page;
 	struct file *filp = vma->vm_file;
 	struct inode *inode = filp->f_path.dentry->d_inode;


 	p9_debug(P9_DEBUG_VFS, "page %p fid %lx\n",
 		 page, (unsigned long)filp->private_data);

 	v9inode = V9FS_I(inode);
 	/* make sure the cache has finished storing the page */
 	v9fs_fscache_wait_on_page_write(inode, page);
 	BUG_ON(!v9inode->writeback_fid);
 	lock_page(page);
 	if (page->mapping != inode->i_mapping)
 		goto out_unlock;

 	return VM_FAULT_LOCKED;
 out_unlock:
 	unlock_page(page);
 	return VM_FAULT_NOPAGE;
 }

 static ssize_t
 v9fs_direct_read(struct file *filp, char __user *udata, size_t count,
 		 loff_t *offsetp)
 {
 	loff_t size, offset;
 	struct inode *inode;
 	struct address_space *mapping;

 	offset = *offsetp;
 	mapping = filp->f_mapping;
 	inode = mapping->host;
 	if (!count)
 		return 0;
 	size = i_size_read(inode);
 	if (offset < size)
 		filemap_write_and_wait_range(mapping, offset,
 					     offset + count - 1);

 	return v9fs_file_read(filp, udata, count, offsetp);
 }

 /**
  * v9fs_cached_file_read - read from a file
  * @filp: file pointer to read
  * @udata: user data buffer to read data into
  * @count: size of buffer
  * @offset: offset at which to read data
  *
  */
 static ssize_t
 v9fs_cached_file_read(struct file *filp, char __user *data, size_t count,
 		      loff_t *offset)
 {
 	if (filp->f_flags & O_DIRECT)
 		return v9fs_direct_read(filp, data, count, offset);
 	return do_sync_read(filp, data, count, offset);
 }

 static ssize_t
 v9fs_direct_write(struct file *filp, const char __user * data,
 		  size_t count, loff_t *offsetp)
 {
 	loff_t offset;
 	ssize_t retval;
 	struct inode *inode;
 	struct address_space *mapping;

 	offset = *offsetp;
 	mapping = filp->f_mapping;
 	inode = mapping->host;
 	if (!count)
 		return 0;

 	mutex_lock(&inode->i_mutex);
 	retval = filemap_write_and_wait_range(mapping, offset,
 					      offset + count - 1);
 	if (retval)
 		goto err_out;
 	/*
 	 * After a write we want buffered reads to be sure to go to disk to get
 	 * the new data.  We invalidate clean cached page from the region we're
 	 * about to write.  We do this *before* the write so that if we fail
 	 * here we fall back to buffered write
 	 */
 	if (mapping->nrpages) {
 		pgoff_t pg_start = offset >> PAGE_CACHE_SHIFT;
 		pgoff_t pg_end   = (offset + count - 1) >> PAGE_CACHE_SHIFT;

 		retval = invalidate_inode_pages2_range(mapping,
 							pg_start, pg_end);
 		/*
 		 * If a page can not be invalidated, fall back
 		 * to buffered write.
 		 */
 		if (retval) {
 			if (retval == -EBUSY)
 				goto buff_write;
 			goto err_out;
 		}
 	}
 	retval = v9fs_file_write(filp, data, count, offsetp);
 err_out:
 	mutex_unlock(&inode->i_mutex);
 	return retval;

 buff_write:
 	mutex_unlock(&inode->i_mutex);
 	return do_sync_write(filp, data, count, offsetp);
 }

 /**
  * v9fs_cached_file_write - write to a file
  * @filp: file pointer to write
  * @data: data buffer to write data from
  * @count: size of buffer
  * @offset: offset at which to write data
  *
  */
 static ssize_t
 v9fs_cached_file_write(struct file *filp, const char __user * data,
 		       size_t count, loff_t *offset)
 {

 	if (filp->f_flags & O_DIRECT)
 		return v9fs_direct_write(filp, data, count, offset);
 	return do_sync_write(filp, data, count, offset);
 }

 static const struct vm_operations_struct v9fs_file_vm_ops = {
 	.fault = filemap_fault,
 	.page_mkwrite = v9fs_vm_page_mkwrite,
 };


 const struct file_operations v9fs_cached_file_operations = {
 	.llseek = generic_file_llseek,
 	.read = v9fs_cached_file_read,
 	.write = v9fs_cached_file_write,
 	.aio_read = generic_file_aio_read,
 	.aio_write = generic_file_aio_write,
 	.open = v9fs_file_open,
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock,
 	.mmap = v9fs_file_mmap,
 	.fsync = v9fs_file_fsync,
 };

 const struct file_operations v9fs_cached_file_operations_dotl = {
 	.llseek = generic_file_llseek,
 	.read = v9fs_cached_file_read,
 	.write = v9fs_cached_file_write,
 	.aio_read = generic_file_aio_read,
 	.aio_write = generic_file_aio_write,
 	.open = v9fs_file_open,
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock_dotl,
 	.flock = v9fs_file_flock_dotl,
 	.mmap = v9fs_file_mmap,
 	.fsync = v9fs_file_fsync_dotl,
 };

 const struct file_operations v9fs_file_operations = {
 	.llseek = generic_file_llseek,
 	.read = v9fs_file_read,
 	.write = v9fs_file_write,
 	.open = v9fs_file_open,
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock,
 	.mmap = generic_file_readonly_mmap,
 	.fsync = v9fs_file_fsync,
 };

 const struct file_operations v9fs_file_operations_dotl = {
 	.llseek = generic_file_llseek,
 	.read = v9fs_file_read,
 	.write = v9fs_file_write,
 	.open = v9fs_file_open,
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock_dotl,
 	.flock = v9fs_file_flock_dotl,
 	.mmap = generic_file_readonly_mmap,
 	.fsync = v9fs_file_fsync_dotl,
 };
	/*
	* linux/fs/9p/vfs_file.c
	*
	* This file contians vfs file ops for 9P2000.
	*
	* Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
	* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2
	* as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to:
	* Free Software Foundation
	* 51 Franklin Street, Fifth Floor
	* Boston, MA 02111-1301 USA
	*
	*/

	#include <linux/module.h>
	#include <linux/errno.h>
	#include <linux/fs.h>
	#include <linux/sched.h>
	#include <linux/file.h>
	#include <linux/stat.h>
	#include <linux/string.h>
	#include <linux/inet.h>
	#include <linux/list.h>
	#include <linux/pagemap.h>
	#include <linux/utsname.h>
	#include <asm/uaccess.h>
	#include <linux/idr.h>
	#include <net/9p/9p.h>
	#include <net/9p/client.h>

	#include "v9fs.h"
	#include "v9fs_vfs.h"
	#include "fid.h"
	#include "cache.h"

	static const struct vm_operations_struct v9fs_file_vm_ops;

	/**
	* v9fs_file_open - open a file (or directory)
	* @inode: inode to be opened
	* @file: file being opened
	*
	*/

	int v9fs_file_open(struct inode inode, struct file file)
	{
	int err;
	struct v9fs_inode *v9inode;
	struct v9fs_session_info *v9ses;
	struct p9_fid *fid;
	int omode;

	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
	v9inode = V9FS_I(inode);
	v9ses = v9fs_inode2v9ses(inode);
	if (v9fs_proto_dotl(v9ses))
	omode = v9fs_open_to_dotl_flags(file->f_flags);
	else
	omode = v9fs_uflags2omode(file->f_flags,
	v9fs_proto_dotu(v9ses));
	fid = file->private_data;
	if (!fid) {
	fid = v9fs_fid_clone(file->f_path.dentry);
	if (IS_ERR(fid))
	return PTR_ERR(fid);

	err = p9_client_open(fid, omode);
	if (err < 0) {
	p9_client_clunk(fid);
	return err;
	}
	if (file->f_flags & O_TRUNC) {
	i_size_write(inode, 0);
	inode->i_blocks = 0;
	}
	if ((file->f_flags & O_APPEND) &&
	(!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
	generic_file_llseek(file, 0, SEEK_END);
	}

	file->private_data = fid;
	mutex_lock(&v9inode->v_mutex);
	if (v9ses->cache && !v9inode->writeback_fid &&
	((file->f_flags & O_ACCMODE) != O_RDONLY)) {
	/*
	* clone a fid and add it to writeback_fid
	* we do it during open time instead of
	* page dirty time via write_begin/page_mkwrite
	* because we want write after unlink usecase
	* to work.
	*/
	fid = v9fs_writeback_fid(file->f_path.dentry);
	if (IS_ERR(fid)) {
	err = PTR_ERR(fid);
	mutex_unlock(&v9inode->v_mutex);
	goto out_error;
	}
	v9inode->writeback_fid = (void *) fid;
	}
	mutex_unlock(&v9inode->v_mutex);
	#ifdef CONFIG_9P_FSCACHE
	if (v9ses->cache)
	v9fs_cache_inode_set_cookie(inode, file);
	#endif
	return 0;
	out_error:
	p9_client_clunk(file->private_data);
	file->private_data = NULL;
	return err;
	}

	/**
	* v9fs_file_lock - lock a file (or directory)
	* @filp: file to be locked
	* @cmd: lock command
	* @fl: file lock structure
	*
	* Bugs: this looks like a local only lock, we should extend into 9P
	* by using open exclusive
	*/

	static int v9fs_file_lock(struct file filp, int cmd, struct file_lock fl)
	{
	int res = 0;
	struct inode *inode = filp->f_path.dentry->d_inode;

	p9_debug(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);

	/* No mandatory locks */
	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
	return -ENOLCK;

	if ((IS_SETLK(cmd) \|\| IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
	filemap_write_and_wait(inode->i_mapping);
	invalidate_mapping_pages(&inode->i_data, 0, -1);
	}

	return res;
	}

	static int v9fs_file_do_lock(struct file filp, int cmd, struct file_lock fl)
	{
	struct p9_flock flock;
	struct p9_fid *fid;
	uint8_t status;
	int res = 0;
	unsigned char fl_type;

	fid = filp->private_data;
	BUG_ON(fid == NULL);

	if ((fl->fl_flags & FL_POSIX) != FL_POSIX)
	BUG();

	res = posix_lock_file_wait(filp, fl);
	if (res < 0)
	goto out;

	/* convert posix lock to p9 tlock args */
	memset(&flock, 0, sizeof(flock));
	/* map the lock type */
	switch (fl->fl_type) {
	case F_RDLCK:
	flock.type = P9_LOCK_TYPE_RDLCK;
	break;
	case F_WRLCK:
	flock.type = P9_LOCK_TYPE_WRLCK;
	break;
	case F_UNLCK:
	flock.type = P9_LOCK_TYPE_UNLCK;
	break;
	}
	flock.start = fl->fl_start;
	if (fl->fl_end == OFFSET_MAX)
	flock.length = 0;
	else
	flock.length = fl->fl_end - fl->fl_start + 1;
	flock.proc_id = fl->fl_pid;
	flock.client_id = utsname()->nodename;
	if (IS_SETLKW(cmd))
	flock.flags = P9_LOCK_FLAGS_BLOCK;

	/*
	* if its a blocked request and we get P9_LOCK_BLOCKED as the status
	* for lock request, keep on trying
	*/
	for (;;) {
	res = p9_client_lock_dotl(fid, &flock, &status);
	if (res < 0)
	break;

	if (status != P9_LOCK_BLOCKED)
	break;
	if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
	break;
	if (schedule_timeout_interruptible(P9_LOCK_TIMEOUT) != 0)
	break;
	}

	/* map 9p status to VFS status */
	switch (status) {
	case P9_LOCK_SUCCESS:
	res = 0;
	break;
	case P9_LOCK_BLOCKED:
	res = -EAGAIN;
	break;
	case P9_LOCK_ERROR:
	case P9_LOCK_GRACE:
	res = -ENOLCK;
	break;
	default:
	BUG();
	}

	/*
	* incase server returned error for lock request, revert
	* it locally
	*/
	if (res < 0 && fl->fl_type != F_UNLCK) {
	fl_type = fl->fl_type;
	fl->fl_type = F_UNLCK;
	res = posix_lock_file_wait(filp, fl);
	fl->fl_type = fl_type;
	}
	out:
	return res;
	}

	static int v9fs_file_getlock(struct file filp, struct file_lock fl)
	{
	struct p9_getlock glock;
	struct p9_fid *fid;
	int res = 0;

	fid = filp->private_data;
	BUG_ON(fid == NULL);

	posix_test_lock(filp, fl);
	/*
	* if we have a conflicting lock locally, no need to validate
	* with server
	*/
	if (fl->fl_type != F_UNLCK)
	return res;

	/* convert posix lock to p9 tgetlock args */
	memset(&glock, 0, sizeof(glock));
	glock.type = P9_LOCK_TYPE_UNLCK;
	glock.start = fl->fl_start;
	if (fl->fl_end == OFFSET_MAX)
	glock.length = 0;
	else
	glock.length = fl->fl_end - fl->fl_start + 1;
	glock.proc_id = fl->fl_pid;
	glock.client_id = utsname()->nodename;

	res = p9_client_getlock_dotl(fid, &glock);
	if (res < 0)
	return res;
	/* map 9p lock type to os lock type */
	switch (glock.type) {
	case P9_LOCK_TYPE_RDLCK:
	fl->fl_type = F_RDLCK;
	break;
	case P9_LOCK_TYPE_WRLCK:
	fl->fl_type = F_WRLCK;
	break;
	case P9_LOCK_TYPE_UNLCK:
	fl->fl_type = F_UNLCK;
	break;
	}
	if (glock.type != P9_LOCK_TYPE_UNLCK) {
	fl->fl_start = glock.start;
	if (glock.length == 0)
	fl->fl_end = OFFSET_MAX;
	else
	fl->fl_end = glock.start + glock.length - 1;
	fl->fl_pid = glock.proc_id;
	}
	return res;
	}

	/**
	* v9fs_file_lock_dotl - lock a file (or directory)
	* @filp: file to be locked
	* @cmd: lock command
	* @fl: file lock structure
	*
	*/

	static int v9fs_file_lock_dotl(struct file filp, int cmd, struct file_lock fl)
	{
	struct inode *inode = filp->f_path.dentry->d_inode;
	int ret = -ENOLCK;

	p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n",
	filp, cmd, fl, filp->f_path.dentry->d_name.name);

	/* No mandatory locks */
	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
	goto out_err;

	if ((IS_SETLK(cmd) \|\| IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
	filemap_write_and_wait(inode->i_mapping);
	invalidate_mapping_pages(&inode->i_data, 0, -1);
	}

	if (IS_SETLK(cmd) \|\| IS_SETLKW(cmd))
	ret = v9fs_file_do_lock(filp, cmd, fl);
	else if (IS_GETLK(cmd))
	ret = v9fs_file_getlock(filp, fl);
	else
	ret = -EINVAL;
	out_err:
	return ret;
	}

	/**
	* v9fs_file_flock_dotl - lock a file
	* @filp: file to be locked
	* @cmd: lock command
	* @fl: file lock structure
	*
	*/

	static int v9fs_file_flock_dotl(struct file *filp, int cmd,
	struct file_lock *fl)
	{
	struct inode *inode = filp->f_path.dentry->d_inode;
	int ret = -ENOLCK;

	p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n",
	filp, cmd, fl, filp->f_path.dentry->d_name.name);

	/* No mandatory locks */
	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
	goto out_err;

	if (!(fl->fl_flags & FL_FLOCK))
	goto out_err;

	if ((IS_SETLK(cmd) \|\| IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
	filemap_write_and_wait(inode->i_mapping);
	invalidate_mapping_pages(&inode->i_data, 0, -1);
	}
	/* Convert flock to posix lock */
	fl->fl_owner = (fl_owner_t)filp;
	fl->fl_start = 0;
	fl->fl_end = OFFSET_MAX;
	fl->fl_flags \|= FL_POSIX;
	fl->fl_flags ^= FL_FLOCK;

	if (IS_SETLK(cmd) \| IS_SETLKW(cmd))
	ret = v9fs_file_do_lock(filp, cmd, fl);
	else
	ret = -EINVAL;
	out_err:
	return ret;
	}

	/**
	* v9fs_fid_readn - read from a fid
	* @fid: fid to read
	* @data: data buffer to read data into
	* @udata: user data buffer to read data into
	* @count: size of buffer
	* @offset: offset at which to read data
	*
	*/
	ssize_t
	v9fs_fid_readn(struct p9_fid fid, char data, char __user *udata, u32 count,
	u64 offset)
	{
	int n, total, size;

	p9_debug(P9_DEBUG_VFS, "fid %d offset %llu count %d\n",
	fid->fid, (long long unsigned)offset, count);
	n = 0;
	total = 0;
	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
	do {
	n = p9_client_read(fid, data, udata, offset, count);
	if (n <= 0)
	break;

	if (data)
	data += n;
	if (udata)
	udata += n;

	offset += n;
	count -= n;
	total += n;
	} while (count > 0 && n == size);

	if (n < 0)
	total = n;

	return total;
	}

	/**
	* v9fs_file_readn - read from a file
	* @filp: file pointer to read
	* @data: data buffer to read data into
	* @udata: user data buffer to read data into
	* @count: size of buffer
	* @offset: offset at which to read data
	*
	*/
	ssize_t
	v9fs_file_readn(struct file filp, char data, char __user *udata, u32 count,
	u64 offset)
	{
	return v9fs_fid_readn(filp->private_data, data, udata, count, offset);
	}

	/**
	* v9fs_file_read - read from a file
	* @filp: file pointer to read
	* @udata: user data buffer to read data into
	* @count: size of buffer
	* @offset: offset at which to read data
	*
	*/

	static ssize_t
	v9fs_file_read(struct file filp, char __user udata, size_t count,
	loff_t * offset)
	{
	int ret;
	struct p9_fid *fid;
	size_t size;

	p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n", count, *offset);
	fid = filp->private_data;

	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
	if (count > size)
	ret = v9fs_file_readn(filp, NULL, udata, count, *offset);
	else
	ret = p9_client_read(fid, NULL, udata, *offset, count);

	if (ret > 0)
	*offset += ret;

	return ret;
	}

	ssize_t
	v9fs_file_write_internal(struct inode inode, struct p9_fid fid,
	const char __user *data, size_t count,
	loff_t *offset, int invalidate)
	{
	int n;
	loff_t i_size;
	size_t total = 0;
	struct p9_client *clnt;
	loff_t origin = *offset;
	unsigned long pg_start, pg_end;

	p9_debug(P9_DEBUG_VFS, "data %p count %d offset %x\n",
	data, (int)count, (int)*offset);

	clnt = fid->clnt;
	do {
	n = p9_client_write(fid, NULL, data+total, origin+total, count);
	if (n <= 0)
	break;
	count -= n;
	total += n;
	} while (count > 0);

	if (invalidate && (total > 0)) {
	pg_start = origin >> PAGE_CACHE_SHIFT;
	pg_end = (origin + total - 1) >> PAGE_CACHE_SHIFT;
	if (inode->i_mapping && inode->i_mapping->nrpages)
	invalidate_inode_pages2_range(inode->i_mapping,
	pg_start, pg_end);
	*offset += total;
	i_size = i_size_read(inode);
	if (*offset > i_size) {
	inode_add_bytes(inode, *offset - i_size);
	i_size_write(inode, *offset);
	}
	}
	if (n < 0)
	return n;

	return total;
	}

	/**
	* v9fs_file_write - write to a file
	* @filp: file pointer to write
	* @data: data buffer to write data from
	* @count: size of buffer
	* @offset: offset at which to write data
	*
	*/
	static ssize_t
	v9fs_file_write(struct file filp, const char __user data,
	size_t count, loff_t *offset)
	{
	ssize_t retval = 0;
	loff_t origin = *offset;


	retval = generic_write_checks(filp, &origin, &count, 0);
	if (retval)
	goto out;

	retval = -EINVAL;
	if ((ssize_t) count < 0)
	goto out;
	retval = 0;
	if (!count)
	goto out;

	retval = v9fs_file_write_internal(filp->f_path.dentry->d_inode,
	filp->private_data,
	data, count, &origin, 1);
	/* update offset on successful write */
	if (retval > 0)
	*offset = origin;
	out:
	return retval;
	}


	static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
	int datasync)
	{
	struct p9_fid *fid;
	struct inode *inode = filp->f_mapping->host;
	struct p9_wstat wstat;
	int retval;

	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
	if (retval)
	return retval;

	mutex_lock(&inode->i_mutex);
	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);

	fid = filp->private_data;
	v9fs_blank_wstat(&wstat);

	retval = p9_client_wstat(fid, &wstat);
	mutex_unlock(&inode->i_mutex);

	return retval;
	}

	int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
	int datasync)
	{
	struct p9_fid *fid;
	struct inode *inode = filp->f_mapping->host;
	int retval;

	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
	if (retval)
	return retval;

	mutex_lock(&inode->i_mutex);
	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);

	fid = filp->private_data;

	retval = p9_client_fsync(fid, datasync);
	mutex_unlock(&inode->i_mutex);

	return retval;
	}

	static int
	v9fs_file_mmap(struct file file, struct vm_area_struct vma)
	{
	int retval;

	retval = generic_file_mmap(file, vma);
	if (!retval)
	vma->vm_ops = &v9fs_file_vm_ops;

	return retval;
	}

	static int
	v9fs_vm_page_mkwrite(struct vm_area_struct vma, struct vm_fault vmf)
	{
	struct v9fs_inode *v9inode;
	struct page *page = vmf->page;
	struct file *filp = vma->vm_file;
	struct inode *inode = filp->f_path.dentry->d_inode;


	p9_debug(P9_DEBUG_VFS, "page %p fid %lx\n",
	page, (unsigned long)filp->private_data);

	v9inode = V9FS_I(inode);
	/* make sure the cache has finished storing the page */
	v9fs_fscache_wait_on_page_write(inode, page);
	BUG_ON(!v9inode->writeback_fid);
	lock_page(page);
	if (page->mapping != inode->i_mapping)
	goto out_unlock;

	return VM_FAULT_LOCKED;
	out_unlock:
	unlock_page(page);
	return VM_FAULT_NOPAGE;
	}

	static ssize_t
	v9fs_direct_read(struct file filp, char __user udata, size_t count,
	loff_t *offsetp)
	{
	loff_t size, offset;
	struct inode *inode;
	struct address_space *mapping;

	offset = *offsetp;
	mapping = filp->f_mapping;
	inode = mapping->host;
	if (!count)
	return 0;
	size = i_size_read(inode);
	if (offset < size)
	filemap_write_and_wait_range(mapping, offset,
	offset + count - 1);

	return v9fs_file_read(filp, udata, count, offsetp);
	}

	/**
	* v9fs_cached_file_read - read from a file
	* @filp: file pointer to read
	* @udata: user data buffer to read data into
	* @count: size of buffer
	* @offset: offset at which to read data
	*
	*/
	static ssize_t
	v9fs_cached_file_read(struct file filp, char __user data, size_t count,
	loff_t *offset)
	{
	if (filp->f_flags & O_DIRECT)
	return v9fs_direct_read(filp, data, count, offset);
	return do_sync_read(filp, data, count, offset);
	}

	static ssize_t
	v9fs_direct_write(struct file filp, const char __user data,
	size_t count, loff_t *offsetp)
	{
	loff_t offset;
	ssize_t retval;
	struct inode *inode;
	struct address_space *mapping;

	offset = *offsetp;
	mapping = filp->f_mapping;
	inode = mapping->host;
	if (!count)
	return 0;

	mutex_lock(&inode->i_mutex);
	retval = filemap_write_and_wait_range(mapping, offset,
	offset + count - 1);
	if (retval)
	goto err_out;
	/*
	* After a write we want buffered reads to be sure to go to disk to get
	* the new data. We invalidate clean cached page from the region we're
	* about to write. We do this before the write so that if we fail
	* here we fall back to buffered write
	*/
	if (mapping->nrpages) {
	pgoff_t pg_start = offset >> PAGE_CACHE_SHIFT;
	pgoff_t pg_end = (offset + count - 1) >> PAGE_CACHE_SHIFT;

	retval = invalidate_inode_pages2_range(mapping,
	pg_start, pg_end);
	/*
	* If a page can not be invalidated, fall back
	* to buffered write.
	*/
	if (retval) {
	if (retval == -EBUSY)
	goto buff_write;
	goto err_out;
	}
	}
	retval = v9fs_file_write(filp, data, count, offsetp);
	err_out:
	mutex_unlock(&inode->i_mutex);
	return retval;

	buff_write:
	mutex_unlock(&inode->i_mutex);
	return do_sync_write(filp, data, count, offsetp);
	}

	/**
	* v9fs_cached_file_write - write to a file
	* @filp: file pointer to write
	* @data: data buffer to write data from
	* @count: size of buffer
	* @offset: offset at which to write data
	*
	*/
	static ssize_t
	v9fs_cached_file_write(struct file filp, const char __user data,
	size_t count, loff_t *offset)
	{

	if (filp->f_flags & O_DIRECT)
	return v9fs_direct_write(filp, data, count, offset);
	return do_sync_write(filp, data, count, offset);
	}

	static const struct vm_operations_struct v9fs_file_vm_ops = {
	.fault = filemap_fault,
	.page_mkwrite = v9fs_vm_page_mkwrite,
	};


	const struct file_operations v9fs_cached_file_operations = {
	.llseek = generic_file_llseek,
	.read = v9fs_cached_file_read,
	.write = v9fs_cached_file_write,
	.aio_read = generic_file_aio_read,
	.aio_write = generic_file_aio_write,
	.open = v9fs_file_open,
	.release = v9fs_dir_release,
	.lock = v9fs_file_lock,
	.mmap = v9fs_file_mmap,
	.fsync = v9fs_file_fsync,
	};

	const struct file_operations v9fs_cached_file_operations_dotl = {
	.llseek = generic_file_llseek,
	.read = v9fs_cached_file_read,
	.write = v9fs_cached_file_write,
	.aio_read = generic_file_aio_read,
	.aio_write = generic_file_aio_write,
	.open = v9fs_file_open,
	.release = v9fs_dir_release,
	.lock = v9fs_file_lock_dotl,
	.flock = v9fs_file_flock_dotl,
	.mmap = v9fs_file_mmap,
	.fsync = v9fs_file_fsync_dotl,
	};

	const struct file_operations v9fs_file_operations = {
	.llseek = generic_file_llseek,
	.read = v9fs_file_read,
	.write = v9fs_file_write,
	.open = v9fs_file_open,
	.release = v9fs_dir_release,
	.lock = v9fs_file_lock,
	.mmap = generic_file_readonly_mmap,
	.fsync = v9fs_file_fsync,
	};

	const struct file_operations v9fs_file_operations_dotl = {
	.llseek = generic_file_llseek,
	.read = v9fs_file_read,
	.write = v9fs_file_write,
	.open = v9fs_file_open,
	.release = v9fs_dir_release,
	.lock = v9fs_file_lock_dotl,
	.flock = v9fs_file_flock_dotl,
	.mmap = generic_file_readonly_mmap,
	.fsync = v9fs_file_fsync_dotl,
	};