[linux-2.6-block.git] / fs / jffs2 / file.c

/*
 * 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,
			struct page **pagep, void **fsdata);
static int jffs2_read_folio(struct file *filp, struct folio *folio);

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,
	.splice_write = iter_file_splice_write,
};

/* jffs2_file_inode_operations */

const struct inode_operations jffs2_file_inode_operations =
{
	.get_inode_acl =	jffs2_get_acl,
	.set_acl =	jffs2_set_acl,
	.setattr =	jffs2_setattr,
	.listxattr =	jffs2_listxattr,
};

const struct address_space_operations jffs2_file_address_operations =
{
	.read_folio =	jffs2_read_folio,
	.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\n",
		  __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\n");
	return ret;
}

int __jffs2_read_folio(struct file *file, struct folio *folio)
{
	int ret = jffs2_do_readpage_nolock(folio->mapping->host, &folio->page);
	folio_unlock(folio);
	return ret;
}

static int jffs2_read_folio(struct file *file, struct folio *folio)
{
	struct jffs2_inode_info *f = JFFS2_INODE_INFO(folio->mapping->host);
	int ret;

	mutex_lock(&f->sem);
	ret = __jffs2_read_folio(file, folio);
	mutex_unlock(&f->sem);
	return ret;
}

static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
			loff_t pos, unsigned len,
			struct page **pagep, void **fsdata)
{
	struct page *pg;
	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);
	pgoff_t index = pos >> PAGE_SHIFT;
	int ret = 0;

	jffs2_dbg(1, "%s()\n", __func__);

	if (pos > inode->i_size) {
		/* Make new hole frag from old EOF to new position */
		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 position\n",
			  (unsigned int)inode->i_size, (uint32_t)pos);

		ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
					  ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
		if (ret)
			goto out_err;

		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((uint32_t)pos);
		ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
		ri.offset = cpu_to_je32(inode->i_size);
		ri.dsize = cpu_to_je32((uint32_t)pos - 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_err;
		}
		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\n",
				  ret);
			jffs2_mark_node_obsolete(c, fn->raw);
			jffs2_free_full_dnode(fn);
			jffs2_complete_reservation(c);
			mutex_unlock(&f->sem);
			goto out_err;
		}
		jffs2_complete_reservation(c);
		inode->i_size = pos;
		mutex_unlock(&f->sem);
	}

	/*
	 * While getting a page and reading data in, lock c->alloc_sem until
	 * the page is Uptodate. Otherwise GC task may attempt to read the same
	 * page in read_cache_page(), which causes a deadlock.
	 */
	mutex_lock(&c->alloc_sem);
	pg = grab_cache_page_write_begin(mapping, index);
	if (!pg) {
		ret = -ENOMEM;
		goto release_sem;
	}
	*pagep = pg;

	/*
	 * 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) {
			unlock_page(pg);
			put_page(pg);
			goto release_sem;
		}
	}
	jffs2_dbg(1, "end write_begin(). pg->flags %lx\n", pg->flags);

release_sem:
	mutex_unlock(&c->alloc_sem);
out_err:
	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\n",
		  __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\n",
			  __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\n",
			__func__);
		SetPageError(pg);
		ClearPageUptodate(pg);
	}

	jffs2_dbg(1, "%s() returning %d\n",
		  __func__, writtenlen > 0 ? writtenlen : ret);
	unlock_page(pg);
	put_page(pg);
	return writtenlen > 0 ? writtenlen : ret;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* JFFS2 -- Journalling Flash File System, Version 2.
	3	*
c00c310e	4	* Copyright © 2001-2007 Red Hat, Inc.
6088c058	5	* Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
1da177e4 LT	6	*
	7	* Created by David Woodhouse <dwmw2@infradead.org>
	8	*
	9	* For licensing information, see the file 'LICENCE' in this directory.
	10	*
1da177e4 LT	11	*/
1da177e4 LT	12
5a528957 JP	13	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
5a528957 JP	14
1da177e4	15	#include <linux/kernel.h>
1da177e4 LT	16	#include <linux/fs.h>
	17	#include <linux/time.h>
	18	#include <linux/pagemap.h>
	19	#include <linux/highmem.h>
	20	#include <linux/crc32.h>
	21	#include <linux/jffs2.h>
	22	#include "nodelist.h"
	23
205c109a NP	24	static int jffs2_write_end(struct file filp, struct address_space mapping,
	25	loff_t pos, unsigned len, unsigned copied,
	26	struct page pg, void fsdata);
	27	static int jffs2_write_begin(struct file filp, struct address_space mapping,
9d6b0cd7	28	loff_t pos, unsigned len,
205c109a	29	struct page pagep, void fsdata);
75a47803	30	static int jffs2_read_folio(struct file filp, struct folio folio);
1da177e4	31
02c24a82	32	int jffs2_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
1da177e4	33	{
7ea80859	34	struct inode *inode = filp->f_mapping->host;
1da177e4	35	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
02c24a82	36	int ret;
1da177e4	37
3b49c9a1	38	ret = file_write_and_wait_range(filp, start, end);
02c24a82 JB	39	if (ret)
	40	return ret;
	41
5955102c	42	inode_lock(inode);
1da177e4 LT	43	/* Trigger GC to flush any pending writes for this inode */
1da177e4 LT	44	jffs2_flush_wbuf_gc(c, inode->i_ino);
5955102c	45	inode_unlock(inode);
182ec4ee TG	46
182ec4ee TG	47	return 0;
1da177e4 LT	48	}
1da177e4 LT	49
4b6f5d20	50	const struct file_operations jffs2_file_operations =
1da177e4 LT	51	{
	52	.llseek = generic_file_llseek,
	53	.open = generic_file_open,
aad4f8bb	54	.read_iter = generic_file_read_iter,
8174202b	55	.write_iter = generic_file_write_iter,
0533400b	56	.unlocked_ioctl=jffs2_ioctl,
1da177e4 LT	57	.mmap = generic_file_readonly_mmap,
1da177e4 LT	58	.fsync = jffs2_fsync,
5ffc4ef4	59	.splice_read = generic_file_splice_read,
42984af0	60	.splice_write = iter_file_splice_write,
1da177e4 LT	61	};
	62
	63	/* jffs2_file_inode_operations */
	64
92e1d5be	65	const struct inode_operations jffs2_file_inode_operations =
1da177e4	66	{
cac2f8b8	67	.get_inode_acl = jffs2_get_acl,
f2963d45	68	.set_acl = jffs2_set_acl,
aa98d7cf	69	.setattr = jffs2_setattr,
aa98d7cf	70	.listxattr = jffs2_listxattr,
1da177e4 LT	71	};
1da177e4 LT	72
f5e54d6e	73	const struct address_space_operations jffs2_file_address_operations =
1da177e4	74	{
75a47803	75	.read_folio = jffs2_read_folio,
205c109a NP	76	.write_begin = jffs2_write_begin,
205c109a NP	77	.write_end = jffs2_write_end,
1da177e4 LT	78	};
	79
	80	static int jffs2_do_readpage_nolock (struct inode inode, struct page pg)
	81	{
	82	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
	83	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
	84	unsigned char *pg_buf;
	85	int ret;
	86
9c261b33	87	jffs2_dbg(2, "%s(): ino #%lu, page at offset 0x%lx\n",
09cbfeaf	88	__func__, inode->i_ino, pg->index << PAGE_SHIFT);
1da177e4	89
cd7619d6	90	BUG_ON(!PageLocked(pg));
1da177e4 LT	91
	92	pg_buf = kmap(pg);
	93	/* FIXME: Can kmap fail? */
	94
09cbfeaf KS	95	ret = jffs2_read_inode_range(c, f, pg_buf, pg->index << PAGE_SHIFT,
09cbfeaf KS	96	PAGE_SIZE);
1da177e4 LT	97
	98	if (ret) {
	99	ClearPageUptodate(pg);
	100	SetPageError(pg);
	101	} else {
	102	SetPageUptodate(pg);
	103	ClearPageError(pg);
	104	}
	105
	106	flush_dcache_page(pg);
	107	kunmap(pg);
	108
9c261b33	109	jffs2_dbg(2, "readpage finished\n");
57ca7deb	110	return ret;
1da177e4 LT	111	}
1da177e4 LT	112
e9b5b23e	113	int __jffs2_read_folio(struct file file, struct folio folio)
1da177e4	114	{
e9b5b23e MWO	115	int ret = jffs2_do_readpage_nolock(folio->mapping->host, &folio->page);
e9b5b23e MWO	116	folio_unlock(folio);
1da177e4 LT	117	return ret;
	118	}
	119
75a47803	120	static int jffs2_read_folio(struct file file, struct folio folio)
1da177e4	121	{
75a47803	122	struct jffs2_inode_info *f = JFFS2_INODE_INFO(folio->mapping->host);
1da177e4	123	int ret;
182ec4ee	124
ced22070	125	mutex_lock(&f->sem);
e9b5b23e	126	ret = __jffs2_read_folio(file, folio);
ced22070	127	mutex_unlock(&f->sem);
1da177e4 LT	128	return ret;
	129	}
	130
205c109a	131	static int jffs2_write_begin(struct file filp, struct address_space mapping,
9d6b0cd7	132	loff_t pos, unsigned len,
205c109a	133	struct page pagep, void fsdata)
1da177e4	134	{
205c109a NP	135	struct page *pg;
205c109a NP	136	struct inode *inode = mapping->host;
1da177e4	137	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
aa39cc67	138	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
09cbfeaf	139	pgoff_t index = pos >> PAGE_SHIFT;
1da177e4 LT	140	int ret = 0;
1da177e4 LT	141
157078f6 TB	142	jffs2_dbg(1, "%s()\n", __func__);
157078f6 TB	143
23892d38 YL	144	if (pos > inode->i_size) {
23892d38 YL	145	/* Make new hole frag from old EOF to new position */
157078f6	146	struct jffs2_raw_inode ri;
1da177e4	147	struct jffs2_full_dnode *fn;
157078f6	148	uint32_t alloc_len;
182ec4ee	149
23892d38 YL	150	jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
23892d38 YL	151	(unsigned int)inode->i_size, (uint32_t)pos);
1da177e4	152
157078f6 TB	153	ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
	154	ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
	155	if (ret)
aa39cc67	156	goto out_err;
157078f6 TB	157
157078f6 TB	158	mutex_lock(&f->sem);
1da177e4 LT	159	memset(&ri, 0, sizeof(ri));
	160
	161	ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
	162	ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
	163	ri.totlen = cpu_to_je32(sizeof(ri));
	164	ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));
	165
	166	ri.ino = cpu_to_je32(f->inocache->ino);
	167	ri.version = cpu_to_je32(++f->highest_version);
	168	ri.mode = cpu_to_jemode(inode->i_mode);
0cfe53d3 EB	169	ri.uid = cpu_to_je16(i_uid_read(inode));
0cfe53d3 EB	170	ri.gid = cpu_to_je16(i_gid_read(inode));
23892d38	171	ri.isize = cpu_to_je32((uint32_t)pos);
c4592b9c	172	ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
1da177e4	173	ri.offset = cpu_to_je32(inode->i_size);
23892d38	174	ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size);
1da177e4 LT	175	ri.csize = cpu_to_je32(0);
	176	ri.compr = JFFS2_COMPR_ZERO;
	177	ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
	178	ri.data_crc = cpu_to_je32(0);
182ec4ee	179
9fe4854c	180	fn = jffs2_write_dnode(c, f, &ri, NULL, 0, ALLOC_NORMAL);
1da177e4 LT	181
	182	if (IS_ERR(fn)) {
	183	ret = PTR_ERR(fn);
	184	jffs2_complete_reservation(c);
157078f6	185	mutex_unlock(&f->sem);
aa39cc67	186	goto out_err;
1da177e4 LT	187	}
	188	ret = jffs2_add_full_dnode_to_inode(c, f, fn);
	189	if (f->metadata) {
	190	jffs2_mark_node_obsolete(c, f->metadata->raw);
	191	jffs2_free_full_dnode(f->metadata);
	192	f->metadata = NULL;
	193	}
	194	if (ret) {
9c261b33 JP	195	jffs2_dbg(1, "Eep. add_full_dnode_to_inode() failed in write_begin, returned %d\n",
9c261b33 JP	196	ret);
1da177e4 LT	197	jffs2_mark_node_obsolete(c, fn->raw);
	198	jffs2_free_full_dnode(fn);
	199	jffs2_complete_reservation(c);
157078f6	200	mutex_unlock(&f->sem);
aa39cc67	201	goto out_err;
1da177e4 LT	202	}
1da177e4 LT	203	jffs2_complete_reservation(c);
23892d38	204	inode->i_size = pos;
157078f6	205	mutex_unlock(&f->sem);
1da177e4	206	}
182ec4ee	207
aa39cc67 KY	208	/*
	209	* While getting a page and reading data in, lock c->alloc_sem until
	210	* the page is Uptodate. Otherwise GC task may attempt to read the same
	211	* page in read_cache_page(), which causes a deadlock.
	212	*/
	213	mutex_lock(&c->alloc_sem);
b7446e7c	214	pg = grab_cache_page_write_begin(mapping, index);
aa39cc67 KY	215	if (!pg) {
	216	ret = -ENOMEM;
	217	goto release_sem;
	218	}
	219	*pagep = pg;
	220
205c109a NP	221	/*
	222	* Read in the page if it wasn't already present. Cannot optimize away
	223	* the whole page write case until jffs2_write_end can handle the
	224	* case of a short-copy.
	225	*/
	226	if (!PageUptodate(pg)) {
157078f6	227	mutex_lock(&f->sem);
1da177e4	228	ret = jffs2_do_readpage_nolock(inode, pg);
157078f6	229	mutex_unlock(&f->sem);
aa39cc67 KY	230	if (ret) {
	231	unlock_page(pg);
	232	put_page(pg);
	233	goto release_sem;
	234	}
1da177e4	235	}
9c261b33	236	jffs2_dbg(1, "end write_begin(). pg->flags %lx\n", pg->flags);
205c109a	237
aa39cc67 KY	238	release_sem:
	239	mutex_unlock(&c->alloc_sem);
	240	out_err:
1da177e4 LT	241	return ret;
	242	}
	243
205c109a NP	244	static int jffs2_write_end(struct file filp, struct address_space mapping,
	245	loff_t pos, unsigned len, unsigned copied,
	246	struct page pg, void fsdata)
1da177e4 LT	247	{
	248	/* Actually commit the write from the page cache page we're looking at.
	249	* For now, we write the full page out each time. It sucks, but it's simple
	250	*/
205c109a	251	struct inode *inode = mapping->host;
1da177e4 LT	252	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
	253	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
	254	struct jffs2_raw_inode *ri;
09cbfeaf	255	unsigned start = pos & (PAGE_SIZE - 1);
205c109a	256	unsigned end = start + copied;
1da177e4 LT	257	unsigned aligned_start = start & ~3;
	258	int ret = 0;
	259	uint32_t writtenlen = 0;
	260
9c261b33	261	jffs2_dbg(1, "%s(): ino #%lu, page at 0x%lx, range %d-%d, flags %lx\n",
09cbfeaf	262	__func__, inode->i_ino, pg->index << PAGE_SHIFT,
9c261b33	263	start, end, pg->flags);
1da177e4	264
205c109a NP	265	/* We need to avoid deadlock with page_cache_read() in
	266	jffs2_garbage_collect_pass(). So the page must be
	267	up to date to prevent page_cache_read() from trying
	268	to re-lock it. */
	269	BUG_ON(!PageUptodate(pg));
	270
09cbfeaf	271	if (end == PAGE_SIZE) {
205c109a NP	272	/* When writing out the end of a page, write out the
	273	_whole_ page. This helps to reduce the number of
	274	nodes in files which have many short writes, like
	275	syslog files. */
2a754b51	276	aligned_start = 0;
1da177e4 LT	277	}
	278
	279	ri = jffs2_alloc_raw_inode();
	280
	281	if (!ri) {
9c261b33 JP	282	jffs2_dbg(1, "%s(): Allocation of raw inode failed\n",
9c261b33 JP	283	__func__);
205c109a	284	unlock_page(pg);
09cbfeaf	285	put_page(pg);
1da177e4 LT	286	return -ENOMEM;
	287	}
	288
	289	/* Set the fields that the generic jffs2_write_inode_range() code can't find */
	290	ri->ino = cpu_to_je32(inode->i_ino);
	291	ri->mode = cpu_to_jemode(inode->i_mode);
0cfe53d3 EB	292	ri->uid = cpu_to_je16(i_uid_read(inode));
0cfe53d3 EB	293	ri->gid = cpu_to_je16(i_gid_read(inode));
1da177e4	294	ri->isize = cpu_to_je32((uint32_t)inode->i_size);
c4592b9c	295	ri->atime = ri->ctime = ri->mtime = cpu_to_je32(JFFS2_NOW());
1da177e4 LT	296
	297	/* In 2.4, it was already kmapped by generic_file_write(). Doesn't
	298	hurt to do it again. The alternative is ifdefs, which are ugly. */
	299	kmap(pg);
	300
	301	ret = jffs2_write_inode_range(c, f, ri, page_address(pg) + aligned_start,
09cbfeaf	302	(pg->index << PAGE_SHIFT) + aligned_start,
1da177e4 LT	303	end - aligned_start, &writtenlen);
	304
	305	kunmap(pg);
	306
	307	if (ret) {
	308	/* There was an error writing. */
	309	SetPageError(pg);
	310	}
182ec4ee	311
1da177e4	312	/* Adjust writtenlen for the padding we did, so we don't confuse our caller */
2a754b51	313	writtenlen -= min(writtenlen, (start - aligned_start));
1da177e4 LT	314
1da177e4 LT	315	if (writtenlen) {
2a754b51 NP	316	if (inode->i_size < pos + writtenlen) {
2a754b51 NP	317	inode->i_size = pos + writtenlen;
1da177e4	318	inode->i_blocks = (inode->i_size + 511) >> 9;
182ec4ee	319
c4592b9c	320	inode->i_ctime = inode->i_mtime = ITIME(je32_to_cpu(ri->ctime));
1da177e4 LT	321	}
	322	}
	323
	324	jffs2_free_raw_inode(ri);
	325
	326	if (start+writtenlen < end) {
	327	/* generic_file_write has written more to the page cache than we've
182ec4ee	328	actually written to the medium. Mark the page !Uptodate so that
1da177e4	329	it gets reread */
9c261b33 JP	330	jffs2_dbg(1, "%s(): Not all bytes written. Marking page !uptodate\n",
9c261b33 JP	331	__func__);
1da177e4 LT	332	SetPageError(pg);
	333	ClearPageUptodate(pg);
	334	}
	335
9c261b33 JP	336	jffs2_dbg(1, "%s() returning %d\n",
9c261b33 JP	337	__func__, writtenlen > 0 ? writtenlen : ret);
205c109a	338	unlock_page(pg);
09cbfeaf	339	put_page(pg);
205c109a	340	return writtenlen > 0 ? writtenlen : ret;
1da177e4	341	}