1 /*
2  * fs/logfs/file.c	- prepare_write, commit_write and friends
3  *
4  * As should be obvious for Linux kernel code, license is GPLv2
5  *
6  * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
7  */
8 #include "logfs.h"
9 #include <linux/sched.h>
10 #include <linux/writeback.h>
11 
logfs_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)12 static int logfs_write_begin(struct file *file, struct address_space *mapping,
13 		loff_t pos, unsigned len, unsigned flags,
14 		struct page **pagep, void **fsdata)
15 {
16 	struct inode *inode = mapping->host;
17 	struct page *page;
18 	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
19 
20 	page = grab_cache_page_write_begin(mapping, index, flags);
21 	if (!page)
22 		return -ENOMEM;
23 	*pagep = page;
24 
25 	if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
26 		return 0;
27 	if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
28 		unsigned start = pos & (PAGE_CACHE_SIZE - 1);
29 		unsigned end = start + len;
30 
31 		/* Reading beyond i_size is simple: memset to zero */
32 		zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
33 		return 0;
34 	}
35 	return logfs_readpage_nolock(page);
36 }
37 
logfs_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)38 static int logfs_write_end(struct file *file, struct address_space *mapping,
39 		loff_t pos, unsigned len, unsigned copied, struct page *page,
40 		void *fsdata)
41 {
42 	struct inode *inode = mapping->host;
43 	pgoff_t index = page->index;
44 	unsigned start = pos & (PAGE_CACHE_SIZE - 1);
45 	unsigned end = start + copied;
46 	int ret = 0;
47 
48 	BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
49 	BUG_ON(page->index > I3_BLOCKS);
50 
51 	if (copied < len) {
52 		/*
53 		 * Short write of a non-initialized paged.  Just tell userspace
54 		 * to retry the entire page.
55 		 */
56 		if (!PageUptodate(page)) {
57 			copied = 0;
58 			goto out;
59 		}
60 	}
61 	if (copied == 0)
62 		goto out; /* FIXME: do we need to update inode? */
63 
64 	if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) {
65 		i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end);
66 		mark_inode_dirty_sync(inode);
67 	}
68 
69 	SetPageUptodate(page);
70 	if (!PageDirty(page)) {
71 		if (!get_page_reserve(inode, page))
72 			__set_page_dirty_nobuffers(page);
73 		else
74 			ret = logfs_write_buf(inode, page, WF_LOCK);
75 	}
76 out:
77 	unlock_page(page);
78 	page_cache_release(page);
79 	return ret ? ret : copied;
80 }
81 
logfs_readpage(struct file * file,struct page * page)82 int logfs_readpage(struct file *file, struct page *page)
83 {
84 	int ret;
85 
86 	ret = logfs_readpage_nolock(page);
87 	unlock_page(page);
88 	return ret;
89 }
90 
91 /* Clear the page's dirty flag in the radix tree. */
92 /* TODO: mucking with PageWriteback is silly.  Add a generic function to clear
93  * the dirty bit from the radix tree for filesystems that don't have to wait
94  * for page writeback to finish (i.e. any compressing filesystem).
95  */
clear_radix_tree_dirty(struct page * page)96 static void clear_radix_tree_dirty(struct page *page)
97 {
98 	BUG_ON(PagePrivate(page) || page->private);
99 	set_page_writeback(page);
100 	end_page_writeback(page);
101 }
102 
__logfs_writepage(struct page * page)103 static int __logfs_writepage(struct page *page)
104 {
105 	struct inode *inode = page->mapping->host;
106 	int err;
107 
108 	err = logfs_write_buf(inode, page, WF_LOCK);
109 	if (err)
110 		set_page_dirty(page);
111 	else
112 		clear_radix_tree_dirty(page);
113 	unlock_page(page);
114 	return err;
115 }
116 
logfs_writepage(struct page * page,struct writeback_control * wbc)117 static int logfs_writepage(struct page *page, struct writeback_control *wbc)
118 {
119 	struct inode *inode = page->mapping->host;
120 	loff_t i_size = i_size_read(inode);
121 	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
122 	unsigned offset;
123 	u64 bix;
124 	level_t level;
125 
126 	log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index,
127 			page);
128 
129 	logfs_unpack_index(page->index, &bix, &level);
130 
131 	/* Indirect blocks are never truncated */
132 	if (level != 0)
133 		return __logfs_writepage(page);
134 
135 	/*
136 	 * TODO: everything below is a near-verbatim copy of nobh_writepage().
137 	 * The relevant bits should be factored out after logfs is merged.
138 	 */
139 
140 	/* Is the page fully inside i_size? */
141 	if (bix < end_index)
142 		return __logfs_writepage(page);
143 
144 	 /* Is the page fully outside i_size? (truncate in progress) */
145 	offset = i_size & (PAGE_CACHE_SIZE-1);
146 	if (bix > end_index || offset == 0) {
147 		unlock_page(page);
148 		return 0; /* don't care */
149 	}
150 
151 	/*
152 	 * The page straddles i_size.  It must be zeroed out on each and every
153 	 * writepage invokation because it may be mmapped.  "A file is mapped
154 	 * in multiples of the page size.  For a file that is not a multiple of
155 	 * the  page size, the remaining memory is zeroed when mapped, and
156 	 * writes to that region are not written out to the file."
157 	 */
158 	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
159 	return __logfs_writepage(page);
160 }
161 
logfs_invalidatepage(struct page * page,unsigned long offset)162 static void logfs_invalidatepage(struct page *page, unsigned long offset)
163 {
164 	struct logfs_block *block = logfs_block(page);
165 
166 	if (block->reserved_bytes) {
167 		struct super_block *sb = page->mapping->host->i_sb;
168 		struct logfs_super *super = logfs_super(sb);
169 
170 		super->s_dirty_pages -= block->reserved_bytes;
171 		block->ops->free_block(sb, block);
172 		BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
173 	} else
174 		move_page_to_btree(page);
175 	BUG_ON(PagePrivate(page) || page->private);
176 }
177 
logfs_releasepage(struct page * page,gfp_t only_xfs_uses_this)178 static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
179 {
180 	return 0; /* None of these are easy to release */
181 }
182 
183 
logfs_ioctl(struct file * file,unsigned int cmd,unsigned long arg)184 long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
185 {
186 	struct inode *inode = file->f_path.dentry->d_inode;
187 	struct logfs_inode *li = logfs_inode(inode);
188 	unsigned int oldflags, flags;
189 	int err;
190 
191 	switch (cmd) {
192 	case FS_IOC_GETFLAGS:
193 		flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
194 		return put_user(flags, (int __user *)arg);
195 	case FS_IOC_SETFLAGS:
196 		if (IS_RDONLY(inode))
197 			return -EROFS;
198 
199 		if (!inode_owner_or_capable(inode))
200 			return -EACCES;
201 
202 		err = get_user(flags, (int __user *)arg);
203 		if (err)
204 			return err;
205 
206 		mutex_lock(&inode->i_mutex);
207 		oldflags = li->li_flags;
208 		flags &= LOGFS_FL_USER_MODIFIABLE;
209 		flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
210 		li->li_flags = flags;
211 		mutex_unlock(&inode->i_mutex);
212 
213 		inode->i_ctime = CURRENT_TIME;
214 		mark_inode_dirty_sync(inode);
215 		return 0;
216 
217 	default:
218 		return -ENOTTY;
219 	}
220 }
221 
logfs_fsync(struct file * file,int datasync)222 int logfs_fsync(struct file *file, int datasync)
223 {
224 	struct super_block *sb = file->f_mapping->host->i_sb;
225 
226 	logfs_write_anchor(sb);
227 	return 0;
228 }
229 
logfs_setattr(struct dentry * dentry,struct iattr * attr)230 static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
231 {
232 	struct inode *inode = dentry->d_inode;
233 	int err = 0;
234 
235 	err = inode_change_ok(inode, attr);
236 	if (err)
237 		return err;
238 
239 	if (attr->ia_valid & ATTR_SIZE) {
240 		err = logfs_truncate(inode, attr->ia_size);
241 		if (err)
242 			return err;
243 	}
244 
245 	setattr_copy(inode, attr);
246 	mark_inode_dirty(inode);
247 	return 0;
248 }
249 
250 const struct inode_operations logfs_reg_iops = {
251 	.setattr	= logfs_setattr,
252 };
253 
254 const struct file_operations logfs_reg_fops = {
255 	.aio_read	= generic_file_aio_read,
256 	.aio_write	= generic_file_aio_write,
257 	.fsync		= logfs_fsync,
258 	.unlocked_ioctl	= logfs_ioctl,
259 	.llseek		= generic_file_llseek,
260 	.mmap		= generic_file_readonly_mmap,
261 	.open		= generic_file_open,
262 	.read		= do_sync_read,
263 	.write		= do_sync_write,
264 };
265 
266 const struct address_space_operations logfs_reg_aops = {
267 	.invalidatepage	= logfs_invalidatepage,
268 	.readpage	= logfs_readpage,
269 	.releasepage	= logfs_releasepage,
270 	.set_page_dirty	= __set_page_dirty_nobuffers,
271 	.writepage	= logfs_writepage,
272 	.writepages	= generic_writepages,
273 	.write_begin	= logfs_write_begin,
274 	.write_end	= logfs_write_end,
275 };
276