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/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * 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 the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
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 * This file implements VFS file and inode operations for regular files, device
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 * nodes and symlinks as well as address space operations.
 *
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 * UBIFS uses 2 page flags: @PG_private and @PG_checked. @PG_private is set if
 * the page is dirty and is used for optimization purposes - dirty pages are
 * not budgeted so the flag shows that 'ubifs_write_end()' should not release
 * the budget for this page. The @PG_checked flag is set if full budgeting is
 * required for the page e.g., when it corresponds to a file hole or it is
 * beyond the file size. The budgeting is done in 'ubifs_write_begin()', because
 * it is OK to fail in this function, and the budget is released in
 * 'ubifs_write_end()'. So the @PG_private and @PG_checked flags carry
 * information about how the page was budgeted, to make it possible to release
 * the budget properly.
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 *
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 * A thing to keep in mind: inode @i_mutex is locked in most VFS operations we
 * implement. However, this is not true for 'ubifs_writepage()', which may be
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 * called with @i_mutex unlocked. For example, when flusher thread is doing
 * background write-back, it calls 'ubifs_writepage()' with unlocked @i_mutex.
 * At "normal" work-paths the @i_mutex is locked in 'ubifs_writepage()', e.g.
 * in the "sys_write -> alloc_pages -> direct reclaim path". So, in
 * 'ubifs_writepage()' we are only guaranteed that the page is locked.
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 *
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 * Similarly, @i_mutex is not always locked in 'ubifs_readpage()', e.g., the
 * read-ahead path does not lock it ("sys_read -> generic_file_aio_read ->
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 * ondemand_readahead -> readpage"). In case of readahead, @I_SYNC flag is not
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 * set as well. However, UBIFS disables readahead.
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 */

#include "ubifs.h"
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#include <linux/aio.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/slab.h>
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static int read_block(struct inode *inode, void *addr, unsigned int block,
		      struct ubifs_data_node *dn)
{
	struct ubifs_info *c = inode->i_sb->s_fs_info;
	int err, len, out_len;
	union ubifs_key key;
	unsigned int dlen;

	data_key_init(c, &key, inode->i_ino, block);
	err = ubifs_tnc_lookup(c, &key, dn);
	if (err) {
		if (err == -ENOENT)
			/* Not found, so it must be a hole */
			memset(addr, 0, UBIFS_BLOCK_SIZE);
		return err;
	}

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	ubifs_assert(le64_to_cpu(dn->ch.sqnum) >
		     ubifs_inode(inode)->creat_sqnum);
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	len = le32_to_cpu(dn->size);
	if (len <= 0 || len > UBIFS_BLOCK_SIZE)
		goto dump;

	dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
	out_len = UBIFS_BLOCK_SIZE;
	err = ubifs_decompress(&dn->data, dlen, addr, &out_len,
			       le16_to_cpu(dn->compr_type));
	if (err || len != out_len)
		goto dump;

	/*
	 * Data length can be less than a full block, even for blocks that are
	 * not the last in the file (e.g., as a result of making a hole and
	 * appending data). Ensure that the remainder is zeroed out.
	 */
	if (len < UBIFS_BLOCK_SIZE)
		memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);

	return 0;

dump:
	ubifs_err("bad data node (block %u, inode %lu)",
		  block, inode->i_ino);
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	ubifs_dump_node(c, dn);
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	return -EINVAL;
}

static int do_readpage(struct page *page)
{
	void *addr;
	int err = 0, i;
	unsigned int block, beyond;
	struct ubifs_data_node *dn;
	struct inode *inode = page->mapping->host;
	loff_t i_size = i_size_read(inode);

	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
		inode->i_ino, page->index, i_size, page->flags);
	ubifs_assert(!PageChecked(page));
	ubifs_assert(!PagePrivate(page));

	addr = kmap(page);

	block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
	beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
	if (block >= beyond) {
		/* Reading beyond inode */
		SetPageChecked(page);
		memset(addr, 0, PAGE_CACHE_SIZE);
		goto out;
	}

	dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS);
	if (!dn) {
		err = -ENOMEM;
		goto error;
	}

	i = 0;
	while (1) {
		int ret;

		if (block >= beyond) {
			/* Reading beyond inode */
			err = -ENOENT;
			memset(addr, 0, UBIFS_BLOCK_SIZE);
		} else {
			ret = read_block(inode, addr, block, dn);
			if (ret) {
				err = ret;
				if (err != -ENOENT)
					break;
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			} else if (block + 1 == beyond) {
				int dlen = le32_to_cpu(dn->size);
				int ilen = i_size & (UBIFS_BLOCK_SIZE - 1);

				if (ilen && ilen < dlen)
					memset(addr + ilen, 0, dlen - ilen);
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			}
		}
		if (++i >= UBIFS_BLOCKS_PER_PAGE)
			break;
		block += 1;
		addr += UBIFS_BLOCK_SIZE;
	}
	if (err) {
		if (err == -ENOENT) {
			/* Not found, so it must be a hole */
			SetPageChecked(page);
			dbg_gen("hole");
			goto out_free;
		}
		ubifs_err("cannot read page %lu of inode %lu, error %d",
			  page->index, inode->i_ino, err);
		goto error;
	}

out_free:
	kfree(dn);
out:
	SetPageUptodate(page);
	ClearPageError(page);
	flush_dcache_page(page);
	kunmap(page);
	return 0;

error:
	kfree(dn);
	ClearPageUptodate(page);
	SetPageError(page);
	flush_dcache_page(page);
	kunmap(page);
	return err;
}

/**
 * release_new_page_budget - release budget of a new page.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which releases budget corresponding to the budget
 * of one new page of data.
 */
static void release_new_page_budget(struct ubifs_info *c)
{
	struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 };

	ubifs_release_budget(c, &req);
}

/**
 * release_existing_page_budget - release budget of an existing page.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which releases budget corresponding to the budget
 * of changing one one page of data which already exists on the flash media.
 */
static void release_existing_page_budget(struct ubifs_info *c)
{
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	struct ubifs_budget_req req = { .dd_growth = c->bi.page_budget};
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	ubifs_release_budget(c, &req);
}

static int write_begin_slow(struct address_space *mapping,
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			    loff_t pos, unsigned len, struct page **pagep,
			    unsigned flags)
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{
	struct inode *inode = mapping->host;
	struct ubifs_info *c = inode->i_sb->s_fs_info;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	struct ubifs_budget_req req = { .new_page = 1 };
	int uninitialized_var(err), appending = !!(pos + len > inode->i_size);
	struct page *page;

	dbg_gen("ino %lu, pos %llu, len %u, i_size %lld",
		inode->i_ino, pos, len, inode->i_size);

	/*
	 * At the slow path we have to budget before locking the page, because
	 * budgeting may force write-back, which would wait on locked pages and
	 * deadlock if we had the page locked. At this point we do not know
	 * anything about the page, so assume that this is a new page which is
	 * written to a hole. This corresponds to largest budget. Later the
	 * budget will be amended if this is not true.
	 */
	if (appending)
		/* We are appending data, budget for inode change */
		req.dirtied_ino = 1;

	err = ubifs_budget_space(c, &req);
	if (unlikely(err))
		return err;

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	page = grab_cache_page_write_begin(mapping, index, flags);
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	if (unlikely(!page)) {
		ubifs_release_budget(c, &req);
		return -ENOMEM;
	}

	if (!PageUptodate(page)) {
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		if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE)
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			SetPageChecked(page);
		else {
			err = do_readpage(page);
			if (err) {
				unlock_page(page);
				page_cache_release(page);
				return err;
			}
		}

		SetPageUptodate(page);
		ClearPageError(page);
	}

	if (PagePrivate(page))
		/*
		 * The page is dirty, which means it was budgeted twice:
		 *   o first time the budget was allocated by the task which
		 *     made the page dirty and set the PG_private flag;
		 *   o and then we budgeted for it for the second time at the
		 *     very beginning of this function.
		 *
		 * So what we have to do is to release the page budget we
		 * allocated.
		 */
		release_new_page_budget(c);
	else if (!PageChecked(page))
		/*
		 * We are changing a page which already exists on the media.
		 * This means that changing the page does not make the amount
		 * of indexing information larger, and this part of the budget
		 * which we have already acquired may be released.
		 */
		ubifs_convert_page_budget(c);

	if (appending) {
		struct ubifs_inode *ui = ubifs_inode(inode);

		/*
		 * 'ubifs_write_end()' is optimized from the fast-path part of
		 * 'ubifs_write_begin()' and expects the @ui_mutex to be locked
		 * if data is appended.
		 */
		mutex_lock(&ui->ui_mutex);
		if (ui->dirty)
			/*
			 * The inode is dirty already, so we may free the
			 * budget we allocated.
			 */
			ubifs_release_dirty_inode_budget(c, ui);
	}

	*pagep = page;
	return 0;
}

/**
 * allocate_budget - allocate budget for 'ubifs_write_begin()'.
 * @c: UBIFS file-system description object
 * @page: page to allocate budget for
 * @ui: UBIFS inode object the page belongs to
 * @appending: non-zero if the page is appended
 *
 * This is a helper function for 'ubifs_write_begin()' which allocates budget
 * for the operation. The budget is allocated differently depending on whether
 * this is appending, whether the page is dirty or not, and so on. This
 * function leaves the @ui->ui_mutex locked in case of appending. Returns zero
 * in case of success and %-ENOSPC in case of failure.
 */
static int allocate_budget(struct ubifs_info *c, struct page *page,
			   struct ubifs_inode *ui, int appending)
{
	struct ubifs_budget_req req = { .fast = 1 };

	if (PagePrivate(page)) {
		if (!appending)
			/*
			 * The page is dirty and we are not appending, which
			 * means no budget is needed at all.
			 */
			return 0;

		mutex_lock(&ui->ui_mutex);
		if (ui->dirty)
			/*
			 * The page is dirty and we are appending, so the inode
			 * has to be marked as dirty. However, it is already
			 * dirty, so we do not need any budget. We may return,
			 * but @ui->ui_mutex hast to be left locked because we
			 * should prevent write-back from flushing the inode
			 * and freeing the budget. The lock will be released in
			 * 'ubifs_write_end()'.
			 */
			return 0;

		/*
		 * The page is dirty, we are appending, the inode is clean, so
		 * we need to budget the inode change.
		 */
		req.dirtied_ino = 1;
	} else {
		if (PageChecked(page))
			/*
			 * The page corresponds to a hole and does not
			 * exist on the media. So changing it makes
			 * make the amount of indexing information
			 * larger, and we have to budget for a new
			 * page.
			 */
			req.new_page = 1;
		else
			/*
			 * Not a hole, the change will not add any new
			 * indexing information, budget for page
			 * change.
			 */
			req.dirtied_page = 1;

		if (appending) {
			mutex_lock(&ui->ui_mutex);
			if (!ui->dirty)
				/*
				 * The inode is clean but we will have to mark
				 * it as dirty because we are appending. This
				 * needs a budget.
				 */
				req.dirtied_ino = 1;
		}
	}

	return ubifs_budget_space(c, &req);
}

/*
 * This function is called when a page of data is going to be written. Since
 * the page of data will not necessarily go to the flash straight away, UBIFS
 * has to reserve space on the media for it, which is done by means of
 * budgeting.
 *
 * This is the hot-path of the file-system and we are trying to optimize it as
 * much as possible. For this reasons it is split on 2 parts - slow and fast.
 *
 * There many budgeting cases:
 *     o a new page is appended - we have to budget for a new page and for
 *       changing the inode; however, if the inode is already dirty, there is
 *       no need to budget for it;
 *     o an existing clean page is changed - we have budget for it; if the page
 *       does not exist on the media (a hole), we have to budget for a new
 *       page; otherwise, we may budget for changing an existing page; the
 *       difference between these cases is that changing an existing page does
 *       not introduce anything new to the FS indexing information, so it does
 *       not grow, and smaller budget is acquired in this case;
 *     o an existing dirty page is changed - no need to budget at all, because
 *       the page budget has been acquired by earlier, when the page has been
 *       marked dirty.
 *
 * UBIFS budgeting sub-system may force write-back if it thinks there is no
 * space to reserve. This imposes some locking restrictions and makes it
 * impossible to take into account the above cases, and makes it impossible to
 * optimize budgeting.
 *
 * The solution for this is that the fast path of 'ubifs_write_begin()' assumes
 * there is a plenty of flash space and the budget will be acquired quickly,
 * without forcing write-back. The slow path does not make this assumption.
 */
static int ubifs_write_begin(struct file *file, struct address_space *mapping,
			     loff_t pos, unsigned len, unsigned flags,
			     struct page **pagep, void **fsdata)
{
	struct inode *inode = mapping->host;
	struct ubifs_info *c = inode->i_sb->s_fs_info;
	struct ubifs_inode *ui = ubifs_inode(inode);
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	int uninitialized_var(err), appending = !!(pos + len > inode->i_size);
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	int skipped_read = 0;
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	struct page *page;

	ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size);
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	ubifs_assert(!c->ro_media && !c->ro_mount);
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	if (unlikely(c->ro_error))
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		return -EROFS;

	/* Try out the fast-path part first */
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	page = grab_cache_page_write_begin(mapping, index, flags);
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	if (unlikely(!page))
		return -ENOMEM;

	if (!PageUptodate(page)) {
		/* The page is not loaded from the flash */
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		if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) {
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			/*
			 * We change whole page so no need to load it. But we
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			 * do not know whether this page exists on the media or
			 * not, so we assume the latter because it requires
			 * larger budget. The assumption is that it is better
			 * to budget a bit more than to read the page from the
			 * media. Thus, we are setting the @PG_checked flag
			 * here.
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			 */
			SetPageChecked(page);
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			skipped_read = 1;
		} else {
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			err = do_readpage(page);
			if (err) {
				unlock_page(page);
				page_cache_release(page);
				return err;
			}
		}

		SetPageUptodate(page);
		ClearPageError(page);
	}

	err = allocate_budget(c, page, ui, appending);
	if (unlikely(err)) {
		ubifs_assert(err == -ENOSPC);
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		/*
		 * If we skipped reading the page because we were going to
		 * write all of it, then it is not up to date.
		 */
		if (skipped_read) {
			ClearPageChecked(page);
			ClearPageUptodate(page);
		}
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		/*
		 * Budgeting failed which means it would have to force
		 * write-back but didn't, because we set the @fast flag in the
		 * request. Write-back cannot be done now, while we have the
		 * page locked, because it would deadlock. Unlock and free
		 * everything and fall-back to slow-path.
		 */
		if (appending) {
			ubifs_assert(mutex_is_locked(&ui->ui_mutex));
			mutex_unlock(&ui->ui_mutex);
		}
		unlock_page(page);
		page_cache_release(page);

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		return write_begin_slow(mapping, pos, len, pagep, flags);
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	}

	/*
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	 * Whee, we acquired budgeting quickly - without involving
	 * garbage-collection, committing or forcing write-back. We return
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	 * with @ui->ui_mutex locked if we are appending pages, and unlocked
	 * otherwise. This is an optimization (slightly hacky though).
	 */
	*pagep = page;
	return 0;

}

/**
 * cancel_budget - cancel budget.
 * @c: UBIFS file-system description object
 * @page: page to cancel budget for
 * @ui: UBIFS inode object the page belongs to
 * @appending: non-zero if the page is appended
 *
 * This is a helper function for a page write operation. It unlocks the
 * @ui->ui_mutex in case of appending.
 */
static void cancel_budget(struct ubifs_info *c, struct page *page,
			  struct ubifs_inode *ui, int appending)
{
	if (appending) {
		if (!ui->dirty)
			ubifs_release_dirty_inode_budget(c, ui);
		mutex_unlock(&ui->ui_mutex);
	}
	if (!PagePrivate(page)) {
		if (PageChecked(page))
			release_new_page_budget(c);
		else
			release_existing_page_budget(c);
	}
}

static int ubifs_write_end(struct file *file, struct address_space *mapping,
			   loff_t pos, unsigned len, unsigned copied,
			   struct page *page, void *fsdata)
{
	struct inode *inode = mapping->host;
	struct ubifs_inode *ui = ubifs_inode(inode);
	struct ubifs_info *c = inode->i_sb->s_fs_info;
	loff_t end_pos = pos + len;
	int appending = !!(end_pos > inode->i_size);

	dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld",
		inode->i_ino, pos, page->index, len, copied, inode->i_size);

	if (unlikely(copied < len && len == PAGE_CACHE_SIZE)) {
		/*
		 * VFS copied less data to the page that it intended and
		 * declared in its '->write_begin()' call via the @len
		 * argument. If the page was not up-to-date, and @len was
		 * @PAGE_CACHE_SIZE, the 'ubifs_write_begin()' function did
		 * not load it from the media (for optimization reasons). This
		 * means that part of the page contains garbage. So read the
		 * page now.
		 */
		dbg_gen("copied %d instead of %d, read page and repeat",
			copied, len);
		cancel_budget(c, page, ui, appending);
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		ClearPageChecked(page);
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		/*
		 * Return 0 to force VFS to repeat the whole operation, or the
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		 * error code if 'do_readpage()' fails.
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		 */
		copied = do_readpage(page);
		goto out;
	}

	if (!PagePrivate(page)) {
		SetPagePrivate(page);
		atomic_long_inc(&c->dirty_pg_cnt);
		__set_page_dirty_nobuffers(page);
	}

	if (appending) {
		i_size_write(inode, end_pos);
		ui->ui_size = end_pos;
		/*
		 * Note, we do not set @I_DIRTY_PAGES (which means that the
		 * inode has dirty pages), this has been done in
		 * '__set_page_dirty_nobuffers()'.
		 */
		__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
		ubifs_assert(mutex_is_locked(&ui->ui_mutex));
		mutex_unlock(&ui->ui_mutex);
	}

out:
	unlock_page(page);
	page_cache_release(page);
	return copied;
}

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/**
 * populate_page - copy data nodes into a page for bulk-read.
 * @c: UBIFS file-system description object
 * @page: page
 * @bu: bulk-read information
 * @n: next zbranch slot
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int populate_page(struct ubifs_info *c, struct page *page,
			 struct bu_info *bu, int *n)
{
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	int i = 0, nn = *n, offs = bu->zbranch[0].offs, hole = 0, read = 0;
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	struct inode *inode = page->mapping->host;
	loff_t i_size = i_size_read(inode);
	unsigned int page_block;
	void *addr, *zaddr;
	pgoff_t end_index;

	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
		inode->i_ino, page->index, i_size, page->flags);

	addr = zaddr = kmap(page);

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	end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
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	if (!i_size || page->index > end_index) {
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		hole = 1;
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		memset(addr, 0, PAGE_CACHE_SIZE);
		goto out_hole;
	}

	page_block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
	while (1) {
		int err, len, out_len, dlen;

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		if (nn >= bu->cnt) {
			hole = 1;
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			memset(addr, 0, UBIFS_BLOCK_SIZE);
638
		} else if (key_block(c, &bu->zbranch[nn].key) == page_block) {
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			struct ubifs_data_node *dn;

			dn = bu->buf + (bu->zbranch[nn].offs - offs);

643
			ubifs_assert(le64_to_cpu(dn->ch.sqnum) >
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				     ubifs_inode(inode)->creat_sqnum);

			len = le32_to_cpu(dn->size);
			if (len <= 0 || len > UBIFS_BLOCK_SIZE)
				goto out_err;

			dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
			out_len = UBIFS_BLOCK_SIZE;
			err = ubifs_decompress(&dn->data, dlen, addr, &out_len,
					       le16_to_cpu(dn->compr_type));
			if (err || len != out_len)
				goto out_err;

			if (len < UBIFS_BLOCK_SIZE)
				memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);

			nn += 1;
			read = (i << UBIFS_BLOCK_SHIFT) + len;
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		} else if (key_block(c, &bu->zbranch[nn].key) < page_block) {
			nn += 1;
			continue;
		} else {
			hole = 1;
			memset(addr, 0, UBIFS_BLOCK_SIZE);
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		}
		if (++i >= UBIFS_BLOCKS_PER_PAGE)
			break;
		addr += UBIFS_BLOCK_SIZE;
		page_block += 1;
	}

	if (end_index == page->index) {
		int len = i_size & (PAGE_CACHE_SIZE - 1);

678
		if (len && len < read)
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			memset(zaddr + len, 0, read - len);
	}

out_hole:
	if (hole) {
		SetPageChecked(page);
		dbg_gen("hole");
	}

	SetPageUptodate(page);
	ClearPageError(page);
	flush_dcache_page(page);
	kunmap(page);
	*n = nn;
	return 0;

out_err:
	ClearPageUptodate(page);
	SetPageError(page);
	flush_dcache_page(page);
	kunmap(page);
	ubifs_err("bad data node (block %u, inode %lu)",
		  page_block, inode->i_ino);
	return -EINVAL;
}

/**
 * ubifs_do_bulk_read - do bulk-read.
 * @c: UBIFS file-system description object
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 * @bu: bulk-read information
 * @page1: first page to read
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 *
 * This function returns %1 if the bulk-read is done, otherwise %0 is returned.
 */
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static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu,
			      struct page *page1)
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{
	pgoff_t offset = page1->index, end_index;
	struct address_space *mapping = page1->mapping;
	struct inode *inode = mapping->host;
	struct ubifs_inode *ui = ubifs_inode(inode);
	int err, page_idx, page_cnt, ret = 0, n = 0;
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	int allocate = bu->buf ? 0 : 1;
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	loff_t isize;

	err = ubifs_tnc_get_bu_keys(c, bu);
	if (err)
		goto out_warn;

	if (bu->eof) {
		/* Turn off bulk-read at the end of the file */
		ui->read_in_a_row = 1;
		ui->bulk_read = 0;
	}

	page_cnt = bu->blk_cnt >> UBIFS_BLOCKS_PER_PAGE_SHIFT;
	if (!page_cnt) {
		/*
		 * This happens when there are multiple blocks per page and the
		 * blocks for the first page we are looking for, are not
		 * together. If all the pages were like this, bulk-read would
		 * reduce performance, so we turn it off for a while.
		 */
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		goto out_bu_off;
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	}

	if (bu->cnt) {
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		if (allocate) {
			/*
			 * Allocate bulk-read buffer depending on how many data
			 * nodes we are going to read.
			 */
			bu->buf_len = bu->zbranch[bu->cnt - 1].offs +
				      bu->zbranch[bu->cnt - 1].len -
				      bu->zbranch[0].offs;
			ubifs_assert(bu->buf_len > 0);
			ubifs_assert(bu->buf_len <= c->leb_size);
			bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN);
			if (!bu->buf)
				goto out_bu_off;
		}

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		err = ubifs_tnc_bulk_read(c, bu);
		if (err)
			goto out_warn;
	}

	err = populate_page(c, page1, bu, &n);
	if (err)
		goto out_warn;

	unlock_page(page1);
	ret = 1;

	isize = i_size_read(inode);
	if (isize == 0)
		goto out_free;
	end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);

	for (page_idx = 1; page_idx < page_cnt; page_idx++) {
		pgoff_t page_offset = offset + page_idx;
		struct page *page;

		if (page_offset > end_index)
			break;
		page = find_or_create_page(mapping, page_offset,
					   GFP_NOFS | __GFP_COLD);
		if (!page)
			break;
		if (!PageUptodate(page))
			err = populate_page(c, page, bu, &n);
		unlock_page(page);
		page_cache_release(page);
		if (err)
			break;
	}

	ui->last_page_read = offset + page_idx - 1;

out_free:
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	if (allocate)
		kfree(bu->buf);
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	return ret;

out_warn:
	ubifs_warn("ignoring error %d and skipping bulk-read", err);
	goto out_free;
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out_bu_off:
	ui->read_in_a_row = ui->bulk_read = 0;
	goto out_free;
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}

/**
 * ubifs_bulk_read - determine whether to bulk-read and, if so, do it.
 * @page: page from which to start bulk-read.
 *
 * Some flash media are capable of reading sequentially at faster rates. UBIFS
 * bulk-read facility is designed to take advantage of that, by reading in one
 * go consecutive data nodes that are also located consecutively in the same
 * LEB. This function returns %1 if a bulk-read is done and %0 otherwise.
 */
static int ubifs_bulk_read(struct page *page)
{
	struct inode *inode = page->mapping->host;
	struct ubifs_info *c = inode->i_sb->s_fs_info;
	struct ubifs_inode *ui = ubifs_inode(inode);
	pgoff_t index = page->index, last_page_read = ui->last_page_read;
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	struct bu_info *bu;
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	int err = 0, allocated = 0;
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	ui->last_page_read = index;
	if (!c->bulk_read)
		return 0;
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	/*
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	 * Bulk-read is protected by @ui->ui_mutex, but it is an optimization,
	 * so don't bother if we cannot lock the mutex.
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	 */
	if (!mutex_trylock(&ui->ui_mutex))
		return 0;
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	if (index != last_page_read + 1) {
		/* Turn off bulk-read if we stop reading sequentially */
		ui->read_in_a_row = 1;
		if (ui->bulk_read)
			ui->bulk_read = 0;
		goto out_unlock;
	}
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	if (!ui->bulk_read) {
		ui->read_in_a_row += 1;
		if (ui->read_in_a_row < 3)
			goto out_unlock;
		/* Three reads in a row, so switch on bulk-read */
		ui->bulk_read = 1;
	}
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	/*
	 * If possible, try to use pre-allocated bulk-read information, which
	 * is protected by @c->bu_mutex.
	 */
	if (mutex_trylock(&c->bu_mutex))
		bu = &c->bu;
	else {
		bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
		if (!bu)
			goto out_unlock;

		bu->buf = NULL;
		allocated = 1;
	}
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	bu->buf_len = c->max_bu_buf_len;
	data_key_init(c, &bu->key, inode->i_ino,
		      page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT);
	err = ubifs_do_bulk_read(c, bu, page);
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	if (!allocated)
		mutex_unlock(&c->bu_mutex);
	else
		kfree(bu);
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out_unlock:
	mutex_unlock(&ui->ui_mutex);
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	return err;
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}

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static int ubifs_readpage(struct file *file, struct page *page)
{
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	if (ubifs_bulk_read(page))
		return 0;
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	do_readpage(page);
	unlock_page(page);
	return 0;
}

static int do_writepage(struct page *page, int len)
{
	int err = 0, i, blen;
	unsigned int block;
	void *addr;
	union ubifs_key key;
	struct inode *inode = page->mapping->host;
	struct ubifs_info *c = inode->i_sb->s_fs_info;

#ifdef UBIFS_DEBUG
	spin_lock(&ui->ui_lock);
	ubifs_assert(page->index <= ui->synced_i_size << PAGE_CACHE_SIZE);
	spin_unlock(&ui->ui_lock);
#endif

	/* Update radix tree tags */
	set_page_writeback(page);

	addr = kmap(page);
	block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
	i = 0;
	while (len) {
		blen = min_t(int, len, UBIFS_BLOCK_SIZE);
		data_key_init(c, &key, inode->i_ino, block);
		err = ubifs_jnl_write_data(c, inode, &key, addr, blen);
		if (err)
			break;
		if (++i >= UBIFS_BLOCKS_PER_PAGE)
			break;
		block += 1;
		addr += blen;
		len -= blen;
	}
	if (err) {
		SetPageError(page);
		ubifs_err("cannot write page %lu of inode %lu, error %d",
			  page->index, inode->i_ino, err);
		ubifs_ro_mode(c, err);
	}

	ubifs_assert(PagePrivate(page));
	if (PageChecked(page))
		release_new_page_budget(c);
	else
		release_existing_page_budget(c);

	atomic_long_dec(&c->dirty_pg_cnt);
	ClearPagePrivate(page);
	ClearPageChecked(page);

	kunmap(page);
	unlock_page(page);
	end_page_writeback(page);
	return err;
}

/*
 * When writing-back dirty inodes, VFS first writes-back pages belonging to the
 * inode, then the inode itself. For UBIFS this may cause a problem. Consider a
 * situation when a we have an inode with size 0, then a megabyte of data is
 * appended to the inode, then write-back starts and flushes some amount of the
 * dirty pages, the journal becomes full, commit happens and finishes, and then
 * an unclean reboot happens. When the file system is mounted next time, the
 * inode size would still be 0, but there would be many pages which are beyond
 * the inode size, they would be indexed and consume flash space. Because the
 * journal has been committed, the replay would not be able to detect this
 * situation and correct the inode size. This means UBIFS would have to scan
 * whole index and correct all inode sizes, which is long an unacceptable.
 *
 * To prevent situations like this, UBIFS writes pages back only if they are
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 * within the last synchronized inode size, i.e. the size which has been
967 968 969 970 971 972 973 974
 * written to the flash media last time. Otherwise, UBIFS forces inode
 * write-back, thus making sure the on-flash inode contains current inode size,
 * and then keeps writing pages back.
 *
 * Some locking issues explanation. 'ubifs_writepage()' first is called with
 * the page locked, and it locks @ui_mutex. However, write-back does take inode
 * @i_mutex, which means other VFS operations may be run on this inode at the
 * same time. And the problematic one is truncation to smaller size, from where
975 976 977 978 979
 * we have to call 'truncate_setsize()', which first changes @inode->i_size,
 * then drops the truncated pages. And while dropping the pages, it takes the
 * page lock. This means that 'do_truncation()' cannot call 'truncate_setsize()'
 * with @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'.
 * This means that @inode->i_size is changed while @ui_mutex is unlocked.
980
 *
981 982 983
 * XXX(truncate): with the new truncate sequence this is not true anymore,
 * and the calls to truncate_setsize can be move around freely.  They should
 * be moved to the very end of the truncate sequence.
984
 *
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 * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond
 * inode size. How do we do this if @inode->i_size may became smaller while we
 * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the
 * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size
 * internally and updates it under @ui_mutex.
 *
 * Q: why we do not worry that if we race with truncation, we may end up with a
 * situation when the inode is truncated while we are in the middle of
 * 'do_writepage()', so we do write beyond inode size?
 * A: If we are in the middle of 'do_writepage()', truncation would be locked
 * on the page lock and it would not write the truncated inode node to the
 * journal before we have finished.
 */
static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	struct ubifs_inode *ui = ubifs_inode(inode);
	loff_t i_size =  i_size_read(inode), synced_i_size;
	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
	int err, len = i_size & (PAGE_CACHE_SIZE - 1);
	void *kaddr;

	dbg_gen("ino %lu, pg %lu, pg flags %#lx",
		inode->i_ino, page->index, page->flags);
	ubifs_assert(PagePrivate(page));

	/* Is the page fully outside @i_size? (truncate in progress) */
	if (page->index > end_index || (page->index == end_index && !len)) {
		err = 0;
		goto out_unlock;
	}

	spin_lock(&ui->ui_lock);
	synced_i_size = ui->synced_i_size;
	spin_unlock(&ui->ui_lock);

	/* Is the page fully inside @i_size? */
	if (page->index < end_index) {
		if (page->index >= synced_i_size >> PAGE_CACHE_SHIFT) {
1024
			err = inode->i_sb->s_op->write_inode(inode, NULL);
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045
			if (err)
				goto out_unlock;
			/*
			 * The inode has been written, but the write-buffer has
			 * not been synchronized, so in case of an unclean
			 * reboot we may end up with some pages beyond inode
			 * size, but they would be in the journal (because
			 * commit flushes write buffers) and recovery would deal
			 * with this.
			 */
		}
		return do_writepage(page, PAGE_CACHE_SIZE);
	}

	/*
	 * The page straddles @i_size. It must be zeroed out on each and every
	 * writepage invocation because it may be mmapped. "A file is mapped
	 * in multiples of the page size. For a file that is not a multiple of
	 * the page size, the remaining memory is zeroed when mapped, and
	 * writes to that region are not written out to the file."
	 */
1046
	kaddr = kmap_atomic(page);
1047 1048
	memset(kaddr + len, 0, PAGE_CACHE_SIZE - len);
	flush_dcache_page(page);
1049
	kunmap_atomic(kaddr);
1050 1051

	if (i_size > synced_i_size) {
1052
		err = inode->i_sb->s_op->write_inode(inode, NULL);
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		if (err)
			goto out_unlock;
	}

	return do_writepage(page, len);

out_unlock:
	unlock_page(page);
	return err;
}

/**
 * do_attr_changes - change inode attributes.
 * @inode: inode to change attributes for
 * @attr: describes attributes to change
 */
static void do_attr_changes(struct inode *inode, const struct iattr *attr)
{
	if (attr->ia_valid & ATTR_UID)
		inode->i_uid = attr->ia_uid;
	if (attr->ia_valid & ATTR_GID)
		inode->i_gid = attr->ia_gid;
	if (attr->ia_valid & ATTR_ATIME)
		inode->i_atime = timespec_trunc(attr->ia_atime,
						inode->i_sb->s_time_gran);
	if (attr->ia_valid & ATTR_MTIME)
		inode->i_mtime = timespec_trunc(attr->ia_mtime,
						inode->i_sb->s_time_gran);
	if (attr->ia_valid & ATTR_CTIME)
		inode->i_ctime = timespec_trunc(attr->ia_ctime,
						inode->i_sb->s_time_gran);
	if (attr->ia_valid & ATTR_MODE) {
		umode_t mode = attr->ia_mode;

		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
			mode &= ~S_ISGID;
		inode->i_mode = mode;
	}
}

/**
 * do_truncation - truncate an inode.
 * @c: UBIFS file-system description object
 * @inode: inode to truncate
 * @attr: inode attribute changes description
 *
 * This function implements VFS '->setattr()' call when the inode is truncated
 * to a smaller size. Returns zero in case of success and a negative error code
 * in case of failure.
 */
static int do_truncation(struct ubifs_info *c, struct inode *inode,
			 const struct iattr *attr)
{
	int err;
	struct ubifs_budget_req req;
	loff_t old_size = inode->i_size, new_size = attr->ia_size;
1109
	int offset = new_size & (UBIFS_BLOCK_SIZE - 1), budgeted = 1;
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	struct ubifs_inode *ui = ubifs_inode(inode);

	dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size);
	memset(&req, 0, sizeof(struct ubifs_budget_req));

	/*
	 * If this is truncation to a smaller size, and we do not truncate on a
	 * block boundary, budget for changing one data block, because the last
	 * block will be re-written.
	 */
	if (new_size & (UBIFS_BLOCK_SIZE - 1))
		req.dirtied_page = 1;

	req.dirtied_ino = 1;
	/* A funny way to budget for truncation node */
	req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ;
	err = ubifs_budget_space(c, &req);
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	if (err) {
		/*
		 * Treat truncations to zero as deletion and always allow them,
		 * just like we do for '->unlink()'.
		 */
		if (new_size || err != -ENOSPC)
			return err;
		budgeted = 0;
	}
1136

1137
	truncate_setsize(inode, new_size);
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	if (offset) {
		pgoff_t index = new_size >> PAGE_CACHE_SHIFT;
		struct page *page;

		page = find_lock_page(inode->i_mapping, index);
		if (page) {
			if (PageDirty(page)) {
				/*
				 * 'ubifs_jnl_truncate()' will try to truncate
				 * the last data node, but it contains
				 * out-of-date data because the page is dirty.
				 * Write the page now, so that
				 * 'ubifs_jnl_truncate()' will see an already
				 * truncated (and up to date) data node.
				 */
				ubifs_assert(PagePrivate(page));

				clear_page_dirty_for_io(page);
				if (UBIFS_BLOCKS_PER_PAGE_SHIFT)
					offset = new_size &
						 (PAGE_CACHE_SIZE - 1);
				err = do_writepage(page, offset);
				page_cache_release(page);
				if (err)
					goto out_budg;
				/*
				 * We could now tell 'ubifs_jnl_truncate()' not
				 * to read the last block.
				 */
			} else {
				/*
				 * We could 'kmap()' the page and pass the data
				 * to 'ubifs_jnl_truncate()' to save it from
				 * having to read it.
				 */
				unlock_page(page);
				page_cache_release(page);
			}
		}
	}

	mutex_lock(&ui->ui_mutex);
	ui->ui_size = inode->i_size;
	/* Truncation changes inode [mc]time */
	inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
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	/* Other attributes may be changed at the same time as well */
1185 1186 1187
	do_attr_changes(inode, attr);
	err = ubifs_jnl_truncate(c, inode, old_size, new_size);
	mutex_unlock(&ui->ui_mutex);
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Artem Bityutskiy 已提交
1188

1189
out_budg:
1190 1191 1192
	if (budgeted)
		ubifs_release_budget(c, &req);
	else {
1193
		c->bi.nospace = c->bi.nospace_rp = 0;
1194 1195
		smp_wmb();
	}
1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215
	return err;
}

/**
 * do_setattr - change inode attributes.
 * @c: UBIFS file-system description object
 * @inode: inode to change attributes for
 * @attr: inode attribute changes description
 *
 * This function implements VFS '->setattr()' call for all cases except
 * truncations to smaller size. Returns zero in case of success and a negative
 * error code in case of failure.
 */
static int do_setattr(struct ubifs_info *c, struct inode *inode,
		      const struct iattr *attr)
{
	int err, release;
	loff_t new_size = attr->ia_size;
	struct ubifs_inode *ui = ubifs_inode(inode);
	struct ubifs_budget_req req = { .dirtied_ino = 1,
1216
				.dirtied_ino_d = ALIGN(ui->data_len, 8) };
1217 1218 1219 1220 1221 1222 1223

	err = ubifs_budget_space(c, &req);
	if (err)
		return err;

	if (attr->ia_valid & ATTR_SIZE) {
		dbg_gen("size %lld -> %lld", inode->i_size, new_size);
1224
		truncate_setsize(inode, new_size);
1225 1226 1227 1228 1229 1230
	}

	mutex_lock(&ui->ui_mutex);
	if (attr->ia_valid & ATTR_SIZE) {
		/* Truncation changes inode [mc]time */
		inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1231
		/* 'truncate_setsize()' changed @i_size, update @ui_size */
1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250
		ui->ui_size = inode->i_size;
	}

	do_attr_changes(inode, attr);

	release = ui->dirty;
	if (attr->ia_valid & ATTR_SIZE)
		/*
		 * Inode length changed, so we have to make sure
		 * @I_DIRTY_DATASYNC is set.
		 */
		 __mark_inode_dirty(inode, I_DIRTY_SYNC | I_DIRTY_DATASYNC);
	else
		mark_inode_dirty_sync(inode);
	mutex_unlock(&ui->ui_mutex);

	if (release)
		ubifs_release_budget(c, &req);
	if (IS_SYNC(inode))
1251
		err = inode->i_sb->s_op->write_inode(inode, NULL);
1252 1253 1254 1255 1256 1257 1258 1259 1260
	return err;
}

int ubifs_setattr(struct dentry *dentry, struct iattr *attr)
{
	int err;
	struct inode *inode = dentry->d_inode;
	struct ubifs_info *c = inode->i_sb->s_fs_info;

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Artem Bityutskiy 已提交
1261 1262
	dbg_gen("ino %lu, mode %#x, ia_valid %#x",
		inode->i_ino, inode->i_mode, attr->ia_valid);
1263 1264 1265 1266
	err = inode_change_ok(inode, attr);
	if (err)
		return err;

1267
	err = dbg_check_synced_i_size(c, inode);
1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279
	if (err)
		return err;

	if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size)
		/* Truncation to a smaller size */
		err = do_truncation(c, inode, attr);
	else
		err = do_setattr(c, inode, attr);

	return err;
}

1280 1281
static void ubifs_invalidatepage(struct page *page, unsigned int offset,
				 unsigned int length)
1282 1283 1284 1285 1286
{
	struct inode *inode = page->mapping->host;
	struct ubifs_info *c = inode->i_sb->s_fs_info;

	ubifs_assert(PagePrivate(page));
1287
	if (offset || length < PAGE_CACHE_SIZE)
1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308
		/* Partial page remains dirty */
		return;

	if (PageChecked(page))
		release_new_page_budget(c);
	else
		release_existing_page_budget(c);

	atomic_long_dec(&c->dirty_pg_cnt);
	ClearPagePrivate(page);
	ClearPageChecked(page);
}

static void *ubifs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	struct ubifs_inode *ui = ubifs_inode(dentry->d_inode);

	nd_set_link(nd, ui->data);
	return NULL;
}

1309
int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1310
{
1311
	struct inode *inode = file->f_mapping->host;
1312 1313 1314 1315 1316
	struct ubifs_info *c = inode->i_sb->s_fs_info;
	int err;

	dbg_gen("syncing inode %lu", inode->i_ino);

1317 1318 1319 1320 1321
	if (c->ro_mount)
		/*
		 * For some really strange reasons VFS does not filter out
		 * 'fsync()' for R/O mounted file-systems as per 2.6.39.
		 */
1322 1323
		return 0;

1324 1325 1326 1327 1328 1329
	err = filemap_write_and_wait_range(inode->i_mapping, start, end);
	if (err)
		return err;
	mutex_lock(&inode->i_mutex);

	/* Synchronize the inode unless this is a 'datasync()' call. */
1330
	if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) {
1331
		err = inode->i_sb->s_op->write_inode(inode, NULL);
1332
		if (err)
1333
			goto out;
1334 1335 1336 1337 1338 1339 1340
	}

	/*
	 * Nodes related to this inode may still sit in a write-buffer. Flush
	 * them.
	 */
	err = ubifs_sync_wbufs_by_inode(c, inode);
1341 1342 1343
out:
	mutex_unlock(&inode->i_mutex);
	return err;
1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380
}

/**
 * mctime_update_needed - check if mtime or ctime update is needed.
 * @inode: the inode to do the check for
 * @now: current time
 *
 * This helper function checks if the inode mtime/ctime should be updated or
 * not. If current values of the time-stamps are within the UBIFS inode time
 * granularity, they are not updated. This is an optimization.
 */
static inline int mctime_update_needed(const struct inode *inode,
				       const struct timespec *now)
{
	if (!timespec_equal(&inode->i_mtime, now) ||
	    !timespec_equal(&inode->i_ctime, now))
		return 1;
	return 0;
}

/**
 * update_ctime - update mtime and ctime of an inode.
 * @c: UBIFS file-system description object
 * @inode: inode to update
 *
 * This function updates mtime and ctime of the inode if it is not equivalent to
 * current time. Returns zero in case of success and a negative error code in
 * case of failure.
 */
static int update_mctime(struct ubifs_info *c, struct inode *inode)
{
	struct timespec now = ubifs_current_time(inode);
	struct ubifs_inode *ui = ubifs_inode(inode);

	if (mctime_update_needed(inode, &now)) {
		int err, release;
		struct ubifs_budget_req req = { .dirtied_ino = 1,
1381
				.dirtied_ino_d = ALIGN(ui->data_len, 8) };
1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409

		err = ubifs_budget_space(c, &req);
		if (err)
			return err;

		mutex_lock(&ui->ui_mutex);
		inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
		release = ui->dirty;
		mark_inode_dirty_sync(inode);
		mutex_unlock(&ui->ui_mutex);
		if (release)
			ubifs_release_budget(c, &req);
	}

	return 0;
}

static ssize_t ubifs_aio_write(struct kiocb *iocb, const struct iovec *iov,
			       unsigned long nr_segs, loff_t pos)
{
	int err;
	struct inode *inode = iocb->ki_filp->f_mapping->host;
	struct ubifs_info *c = inode->i_sb->s_fs_info;

	err = update_mctime(c, inode);
	if (err)
		return err;

1410
	return generic_file_aio_write(iocb, iov, nr_segs, pos);
1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441
}

static int ubifs_set_page_dirty(struct page *page)
{
	int ret;

	ret = __set_page_dirty_nobuffers(page);
	/*
	 * An attempt to dirty a page without budgeting for it - should not
	 * happen.
	 */
	ubifs_assert(ret == 0);
	return ret;
}

static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
{
	/*
	 * An attempt to release a dirty page without budgeting for it - should
	 * not happen.
	 */
	if (PageWriteback(page))
		return 0;
	ubifs_assert(PagePrivate(page));
	ubifs_assert(0);
	ClearPagePrivate(page);
	ClearPageChecked(page);
	return 1;
}

/*
1442 1443
 * mmap()d file has taken write protection fault and is being made writable.
 * UBIFS must ensure page is budgeted for.
1444
 */
1445 1446
static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma,
				 struct vm_fault *vmf)
1447
{
1448
	struct page *page = vmf->page;
A
Al Viro 已提交
1449
	struct inode *inode = file_inode(vma->vm_file);
1450 1451 1452 1453 1454 1455 1456
	struct ubifs_info *c = inode->i_sb->s_fs_info;
	struct timespec now = ubifs_current_time(inode);
	struct ubifs_budget_req req = { .new_page = 1 };
	int err, update_time;

	dbg_gen("ino %lu, pg %lu, i_size %lld",	inode->i_ino, page->index,
		i_size_read(inode));
1457
	ubifs_assert(!c->ro_media && !c->ro_mount);
1458

1459
	if (unlikely(c->ro_error))
1460
		return VM_FAULT_SIGBUS; /* -EROFS */
1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490

	/*
	 * We have not locked @page so far so we may budget for changing the
	 * page. Note, we cannot do this after we locked the page, because
	 * budgeting may cause write-back which would cause deadlock.
	 *
	 * At the moment we do not know whether the page is dirty or not, so we
	 * assume that it is not and budget for a new page. We could look at
	 * the @PG_private flag and figure this out, but we may race with write
	 * back and the page state may change by the time we lock it, so this
	 * would need additional care. We do not bother with this at the
	 * moment, although it might be good idea to do. Instead, we allocate
	 * budget for a new page and amend it later on if the page was in fact
	 * dirty.
	 *
	 * The budgeting-related logic of this function is similar to what we
	 * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there
	 * for more comments.
	 */
	update_time = mctime_update_needed(inode, &now);
	if (update_time)
		/*
		 * We have to change inode time stamp which requires extra
		 * budgeting.
		 */
		req.dirtied_ino = 1;

	err = ubifs_budget_space(c, &req);
	if (unlikely(err)) {
		if (err == -ENOSPC)
1491 1492
			ubifs_warn("out of space for mmapped file (inode number %lu)",
				   inode->i_ino);
1493
		return VM_FAULT_SIGBUS;
1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526
	}

	lock_page(page);
	if (unlikely(page->mapping != inode->i_mapping ||
		     page_offset(page) > i_size_read(inode))) {
		/* Page got truncated out from underneath us */
		err = -EINVAL;
		goto out_unlock;
	}

	if (PagePrivate(page))
		release_new_page_budget(c);
	else {
		if (!PageChecked(page))
			ubifs_convert_page_budget(c);
		SetPagePrivate(page);
		atomic_long_inc(&c->dirty_pg_cnt);
		__set_page_dirty_nobuffers(page);
	}

	if (update_time) {
		int release;
		struct ubifs_inode *ui = ubifs_inode(inode);

		mutex_lock(&ui->ui_mutex);
		inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
		release = ui->dirty;
		mark_inode_dirty_sync(inode);
		mutex_unlock(&ui->ui_mutex);
		if (release)
			ubifs_release_dirty_inode_budget(c, ui);
	}

1527
	wait_for_stable_page(page);
1528 1529 1530 1531 1532 1533
	unlock_page(page);
	return 0;

out_unlock:
	unlock_page(page);
	ubifs_release_budget(c, &req);
1534 1535
	if (err)
		err = VM_FAULT_SIGBUS;
1536 1537 1538
	return err;
}

1539
static const struct vm_operations_struct ubifs_file_vm_ops = {
1540
	.fault        = filemap_fault,
1541
	.map_pages = filemap_map_pages,
1542
	.page_mkwrite = ubifs_vm_page_mkwrite,
1543
	.remap_pages = generic_file_remap_pages,
1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556
};

static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
	int err;

	err = generic_file_mmap(file, vma);
	if (err)
		return err;
	vma->vm_ops = &ubifs_file_vm_ops;
	return 0;
}

A
Artem Bityutskiy 已提交
1557
const struct address_space_operations ubifs_file_address_operations = {
1558 1559 1560 1561 1562 1563 1564 1565 1566
	.readpage       = ubifs_readpage,
	.writepage      = ubifs_writepage,
	.write_begin    = ubifs_write_begin,
	.write_end      = ubifs_write_end,
	.invalidatepage = ubifs_invalidatepage,
	.set_page_dirty = ubifs_set_page_dirty,
	.releasepage    = ubifs_releasepage,
};

A
Artem Bityutskiy 已提交
1567
const struct inode_operations ubifs_file_inode_operations = {
1568 1569 1570 1571 1572 1573 1574 1575
	.setattr     = ubifs_setattr,
	.getattr     = ubifs_getattr,
	.setxattr    = ubifs_setxattr,
	.getxattr    = ubifs_getxattr,
	.listxattr   = ubifs_listxattr,
	.removexattr = ubifs_removexattr,
};

A
Artem Bityutskiy 已提交
1576
const struct inode_operations ubifs_symlink_inode_operations = {
1577 1578 1579 1580 1581 1582
	.readlink    = generic_readlink,
	.follow_link = ubifs_follow_link,
	.setattr     = ubifs_setattr,
	.getattr     = ubifs_getattr,
};

A
Artem Bityutskiy 已提交
1583
const struct file_operations ubifs_file_operations = {
1584 1585 1586 1587 1588 1589 1590 1591 1592
	.llseek         = generic_file_llseek,
	.read           = do_sync_read,
	.write          = do_sync_write,
	.aio_read       = generic_file_aio_read,
	.aio_write      = ubifs_aio_write,
	.mmap           = ubifs_file_mmap,
	.fsync          = ubifs_fsync,
	.unlocked_ioctl = ubifs_ioctl,
	.splice_read	= generic_file_splice_read,
Z
Zoltan Sogor 已提交
1593
	.splice_write	= generic_file_splice_write,
1594 1595 1596 1597
#ifdef CONFIG_COMPAT
	.compat_ioctl   = ubifs_compat_ioctl,
#endif
};