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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
12static 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
38static 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 }
76out:
77 unlock_page(page);
78 page_cache_release(page);
79 return ret ? ret : copied;
80}
81
82int 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 */
96static 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
103static 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
117static 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
162static 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
178static 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
184long 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
222int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
223{
224 struct super_block *sb = file->f_mapping->host->i_sb;
225 struct inode *inode = file->f_mapping->host;
226 int ret;
227
228 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
229 if (ret)
230 return ret;
231
232 mutex_lock(&inode->i_mutex);
233 logfs_get_wblocks(sb, NULL, WF_LOCK);
234 logfs_write_anchor(sb);
235 logfs_put_wblocks(sb, NULL, WF_LOCK);
236 mutex_unlock(&inode->i_mutex);
237
238 return 0;
239}
240
241static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
242{
243 struct inode *inode = dentry->d_inode;
244 int err = 0;
245
246 err = inode_change_ok(inode, attr);
247 if (err)
248 return err;
249
250 if (attr->ia_valid & ATTR_SIZE) {
251 err = logfs_truncate(inode, attr->ia_size);
252 if (err)
253 return err;
254 }
255
256 setattr_copy(inode, attr);
257 mark_inode_dirty(inode);
258 return 0;
259}
260
261const struct inode_operations logfs_reg_iops = {
262 .setattr = logfs_setattr,
263};
264
265const struct file_operations logfs_reg_fops = {
266 .aio_read = generic_file_aio_read,
267 .aio_write = generic_file_aio_write,
268 .fsync = logfs_fsync,
269 .unlocked_ioctl = logfs_ioctl,
270 .llseek = generic_file_llseek,
271 .mmap = generic_file_readonly_mmap,
272 .open = generic_file_open,
273 .read = do_sync_read,
274 .write = do_sync_write,
275};
276
277const struct address_space_operations logfs_reg_aops = {
278 .invalidatepage = logfs_invalidatepage,
279 .readpage = logfs_readpage,
280 .releasepage = logfs_releasepage,
281 .set_page_dirty = __set_page_dirty_nobuffers,
282 .writepage = logfs_writepage,
283 .writepages = generic_writepages,
284 .write_begin = logfs_write_begin,
285 .write_end = logfs_write_end,
286};