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[mirror_ubuntu-bionic-kernel.git] / fs / logfs / file.c
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
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
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
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 */
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
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
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
162 static void logfs_invalidatepage(struct page *page, unsigned int offset,
163 unsigned int length)
164 {
165 struct logfs_block *block = logfs_block(page);
166
167 if (block->reserved_bytes) {
168 struct super_block *sb = page->mapping->host->i_sb;
169 struct logfs_super *super = logfs_super(sb);
170
171 super->s_dirty_pages -= block->reserved_bytes;
172 block->ops->free_block(sb, block);
173 BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
174 } else
175 move_page_to_btree(page);
176 BUG_ON(PagePrivate(page) || page->private);
177 }
178
179 static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
180 {
181 return 0; /* None of these are easy to release */
182 }
183
184
185 long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
186 {
187 struct inode *inode = file_inode(file);
188 struct logfs_inode *li = logfs_inode(inode);
189 unsigned int oldflags, flags;
190 int err;
191
192 switch (cmd) {
193 case FS_IOC_GETFLAGS:
194 flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
195 return put_user(flags, (int __user *)arg);
196 case FS_IOC_SETFLAGS:
197 if (IS_RDONLY(inode))
198 return -EROFS;
199
200 if (!inode_owner_or_capable(inode))
201 return -EACCES;
202
203 err = get_user(flags, (int __user *)arg);
204 if (err)
205 return err;
206
207 mutex_lock(&inode->i_mutex);
208 oldflags = li->li_flags;
209 flags &= LOGFS_FL_USER_MODIFIABLE;
210 flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
211 li->li_flags = flags;
212 mutex_unlock(&inode->i_mutex);
213
214 inode->i_ctime = CURRENT_TIME;
215 mark_inode_dirty_sync(inode);
216 return 0;
217
218 default:
219 return -ENOTTY;
220 }
221 }
222
223 int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
224 {
225 struct super_block *sb = file->f_mapping->host->i_sb;
226 struct inode *inode = file->f_mapping->host;
227 int ret;
228
229 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
230 if (ret)
231 return ret;
232
233 mutex_lock(&inode->i_mutex);
234 logfs_get_wblocks(sb, NULL, WF_LOCK);
235 logfs_write_anchor(sb);
236 logfs_put_wblocks(sb, NULL, WF_LOCK);
237 mutex_unlock(&inode->i_mutex);
238
239 return 0;
240 }
241
242 static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
243 {
244 struct inode *inode = dentry->d_inode;
245 int err = 0;
246
247 err = inode_change_ok(inode, attr);
248 if (err)
249 return err;
250
251 if (attr->ia_valid & ATTR_SIZE) {
252 err = logfs_truncate(inode, attr->ia_size);
253 if (err)
254 return err;
255 }
256
257 setattr_copy(inode, attr);
258 mark_inode_dirty(inode);
259 return 0;
260 }
261
262 const struct inode_operations logfs_reg_iops = {
263 .setattr = logfs_setattr,
264 };
265
266 const struct file_operations logfs_reg_fops = {
267 .read_iter = generic_file_read_iter,
268 .write_iter = generic_file_write_iter,
269 .fsync = logfs_fsync,
270 .unlocked_ioctl = logfs_ioctl,
271 .llseek = generic_file_llseek,
272 .mmap = generic_file_readonly_mmap,
273 .open = generic_file_open,
274 };
275
276 const struct address_space_operations logfs_reg_aops = {
277 .invalidatepage = logfs_invalidatepage,
278 .readpage = logfs_readpage,
279 .releasepage = logfs_releasepage,
280 .set_page_dirty = __set_page_dirty_nobuffers,
281 .writepage = logfs_writepage,
282 .writepages = generic_writepages,
283 .write_begin = logfs_write_begin,
284 .write_end = logfs_write_end,
285 };