/*
   * JFFS2 -- Journalling Flash File System, Version 2.
   *

   * Copyright © 2001-2007 Red Hat, Inc.

   * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>

   *
   * Created by David Woodhouse <dwmw2@infradead.org>
   *
   * For licensing information, see the file 'LICENCE' in this directory.
   *

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.h>

  #include <linux/fs.h>
  #include <linux/time.h>
  #include <linux/pagemap.h>
  #include <linux/highmem.h>
  #include <linux/crc32.h>
  #include <linux/jffs2.h>
  #include "nodelist.h"

  static int jffs2_write_end(struct file *filp, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *pg, void *fsdata);
  static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata);

  static int jffs2_readpage (struct file *filp, struct page *pg);

  int jffs2_fsync(struct file *filp, loff_t start, loff_t end, int datasync)

  {

  	struct inode *inode = filp->f_mapping->host;

  	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);

  	int ret;

  	ret = file_write_and_wait_range(filp, start, end);

  	if (ret)
  		return ret;

  	inode_lock(inode);

  	/* Trigger GC to flush any pending writes for this inode */
  	jffs2_flush_wbuf_gc(c, inode->i_ino);

  	inode_unlock(inode);

  
  	return 0;

  }

  const struct file_operations jffs2_file_operations =

  {
  	.llseek =	generic_file_llseek,
  	.open =		generic_file_open,

   	.read_iter =	generic_file_read_iter,

   	.write_iter =	generic_file_write_iter,

  	.unlocked_ioctl=jffs2_ioctl,

  	.mmap =		generic_file_readonly_mmap,
  	.fsync =	jffs2_fsync,

  	.splice_read =	generic_file_splice_read,

  };
  
  /* jffs2_file_inode_operations */

  const struct inode_operations jffs2_file_inode_operations =

  {

  	.get_acl =	jffs2_get_acl,

  	.set_acl =	jffs2_set_acl,

  	.setattr =	jffs2_setattr,

  	.listxattr =	jffs2_listxattr,

  };

  const struct address_space_operations jffs2_file_address_operations =

  {
  	.readpage =	jffs2_readpage,

  	.write_begin =	jffs2_write_begin,
  	.write_end =	jffs2_write_end,

  };
  
  static int jffs2_do_readpage_nolock (struct inode *inode, struct page *pg)
  {
  	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
  	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
  	unsigned char *pg_buf;
  	int ret;

  	jffs2_dbg(2, "%s(): ino #%lu, page at offset 0x%lx
  ",

  		  __func__, inode->i_ino, pg->index << PAGE_SHIFT);

  	BUG_ON(!PageLocked(pg));

  
  	pg_buf = kmap(pg);
  	/* FIXME: Can kmap fail? */

  	ret = jffs2_read_inode_range(c, f, pg_buf, pg->index << PAGE_SHIFT,
  				     PAGE_SIZE);

  
  	if (ret) {
  		ClearPageUptodate(pg);
  		SetPageError(pg);
  	} else {
  		SetPageUptodate(pg);
  		ClearPageError(pg);
  	}
  
  	flush_dcache_page(pg);
  	kunmap(pg);

  	jffs2_dbg(2, "readpage finished
  ");

  	return ret;

  }

  int jffs2_do_readpage_unlock(void *data, struct page *pg)

  {

  	int ret = jffs2_do_readpage_nolock(data, pg);

  	unlock_page(pg);
  	return ret;
  }
  
  
  static int jffs2_readpage (struct file *filp, struct page *pg)
  {
  	struct jffs2_inode_info *f = JFFS2_INODE_INFO(pg->mapping->host);
  	int ret;

  	mutex_lock(&f->sem);

  	ret = jffs2_do_readpage_unlock(pg->mapping->host, pg);

  	mutex_unlock(&f->sem);

  	return ret;
  }

  static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata)

  {

  	struct page *pg;
  	struct inode *inode = mapping->host;

  	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);

  	pgoff_t index = pos >> PAGE_SHIFT;
  	uint32_t pageofs = index << PAGE_SHIFT;

  	int ret = 0;

  	pg = grab_cache_page_write_begin(mapping, index, flags);

  	if (!pg)

  		return -ENOMEM;
  	*pagep = pg;

  	jffs2_dbg(1, "%s()
  ", __func__);
  
  	if (pageofs > inode->i_size) {

  		/* Make new hole frag from old EOF to new page */

  		struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
  		struct jffs2_raw_inode ri;

  		struct jffs2_full_dnode *fn;

  		uint32_t alloc_len;

  		jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page
  ",
  			  (unsigned int)inode->i_size, pageofs);

  		ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
  					  ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
  		if (ret)
  			goto out_page;
  
  		mutex_lock(&f->sem);

  		memset(&ri, 0, sizeof(ri));
  
  		ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
  		ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
  		ri.totlen = cpu_to_je32(sizeof(ri));
  		ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));
  
  		ri.ino = cpu_to_je32(f->inocache->ino);
  		ri.version = cpu_to_je32(++f->highest_version);
  		ri.mode = cpu_to_jemode(inode->i_mode);

  		ri.uid = cpu_to_je16(i_uid_read(inode));
  		ri.gid = cpu_to_je16(i_gid_read(inode));

  		ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));

  		ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());

  		ri.offset = cpu_to_je32(inode->i_size);
  		ri.dsize = cpu_to_je32(pageofs - inode->i_size);
  		ri.csize = cpu_to_je32(0);
  		ri.compr = JFFS2_COMPR_ZERO;
  		ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
  		ri.data_crc = cpu_to_je32(0);

  		fn = jffs2_write_dnode(c, f, &ri, NULL, 0, ALLOC_NORMAL);

  
  		if (IS_ERR(fn)) {
  			ret = PTR_ERR(fn);
  			jffs2_complete_reservation(c);

  			mutex_unlock(&f->sem);

  			goto out_page;

  		}
  		ret = jffs2_add_full_dnode_to_inode(c, f, fn);
  		if (f->metadata) {
  			jffs2_mark_node_obsolete(c, f->metadata->raw);
  			jffs2_free_full_dnode(f->metadata);
  			f->metadata = NULL;
  		}
  		if (ret) {

  			jffs2_dbg(1, "Eep. add_full_dnode_to_inode() failed in write_begin, returned %d
  ",
  				  ret);

  			jffs2_mark_node_obsolete(c, fn->raw);
  			jffs2_free_full_dnode(fn);
  			jffs2_complete_reservation(c);

  			mutex_unlock(&f->sem);

  			goto out_page;

  		}
  		jffs2_complete_reservation(c);
  		inode->i_size = pageofs;

  		mutex_unlock(&f->sem);

  	}

  	/*
  	 * Read in the page if it wasn't already present. Cannot optimize away
  	 * the whole page write case until jffs2_write_end can handle the
  	 * case of a short-copy.
  	 */
  	if (!PageUptodate(pg)) {

  		mutex_lock(&f->sem);

  		ret = jffs2_do_readpage_nolock(inode, pg);

  		mutex_unlock(&f->sem);

  		if (ret)
  			goto out_page;

  	}

  	jffs2_dbg(1, "end write_begin(). pg->flags %lx
  ", pg->flags);

  	return ret;
  
  out_page:
  	unlock_page(pg);

  	put_page(pg);

  	return ret;
  }

  static int jffs2_write_end(struct file *filp, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *pg, void *fsdata)

  {
  	/* Actually commit the write from the page cache page we're looking at.
  	 * For now, we write the full page out each time. It sucks, but it's simple
  	 */

  	struct inode *inode = mapping->host;

  	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
  	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
  	struct jffs2_raw_inode *ri;

  	unsigned start = pos & (PAGE_SIZE - 1);

  	unsigned end = start + copied;

  	unsigned aligned_start = start & ~3;
  	int ret = 0;
  	uint32_t writtenlen = 0;

  	jffs2_dbg(1, "%s(): ino #%lu, page at 0x%lx, range %d-%d, flags %lx
  ",

  		  __func__, inode->i_ino, pg->index << PAGE_SHIFT,

  		  start, end, pg->flags);

  	/* We need to avoid deadlock with page_cache_read() in
  	   jffs2_garbage_collect_pass(). So the page must be
  	   up to date to prevent page_cache_read() from trying
  	   to re-lock it. */
  	BUG_ON(!PageUptodate(pg));

  	if (end == PAGE_SIZE) {

  		/* When writing out the end of a page, write out the
  		   _whole_ page. This helps to reduce the number of
  		   nodes in files which have many short writes, like
  		   syslog files. */

  		aligned_start = 0;

  	}
  
  	ri = jffs2_alloc_raw_inode();
  
  	if (!ri) {

  		jffs2_dbg(1, "%s(): Allocation of raw inode failed
  ",
  			  __func__);

  		unlock_page(pg);

  		put_page(pg);

  		return -ENOMEM;
  	}
  
  	/* Set the fields that the generic jffs2_write_inode_range() code can't find */
  	ri->ino = cpu_to_je32(inode->i_ino);
  	ri->mode = cpu_to_jemode(inode->i_mode);

  	ri->uid = cpu_to_je16(i_uid_read(inode));
  	ri->gid = cpu_to_je16(i_gid_read(inode));

  	ri->isize = cpu_to_je32((uint32_t)inode->i_size);

  	ri->atime = ri->ctime = ri->mtime = cpu_to_je32(JFFS2_NOW());

  
  	/* In 2.4, it was already kmapped by generic_file_write(). Doesn't
  	   hurt to do it again. The alternative is ifdefs, which are ugly. */
  	kmap(pg);
  
  	ret = jffs2_write_inode_range(c, f, ri, page_address(pg) + aligned_start,

  				      (pg->index << PAGE_SHIFT) + aligned_start,

  				      end - aligned_start, &writtenlen);
  
  	kunmap(pg);
  
  	if (ret) {
  		/* There was an error writing. */
  		SetPageError(pg);
  	}

  	/* Adjust writtenlen for the padding we did, so we don't confuse our caller */

  	writtenlen -= min(writtenlen, (start - aligned_start));

  
  	if (writtenlen) {

  		if (inode->i_size < pos + writtenlen) {
  			inode->i_size = pos + writtenlen;

  			inode->i_blocks = (inode->i_size + 511) >> 9;

  			inode->i_ctime = inode->i_mtime = ITIME(je32_to_cpu(ri->ctime));

  		}
  	}
  
  	jffs2_free_raw_inode(ri);
  
  	if (start+writtenlen < end) {
  		/* generic_file_write has written more to the page cache than we've

  		   actually written to the medium. Mark the page !Uptodate so that

  		   it gets reread */

  		jffs2_dbg(1, "%s(): Not all bytes written. Marking page !uptodate
  ",
  			__func__);

  		SetPageError(pg);
  		ClearPageUptodate(pg);
  	}

  	jffs2_dbg(1, "%s() returning %d
  ",
  		  __func__, writtenlen > 0 ? writtenlen : ret);

  	unlock_page(pg);

  	put_page(pg);

  	return writtenlen > 0 ? writtenlen : ret;

  }