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Linux/fs/jffs2/file.c

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  1 /*
  2  * JFFS2 -- Journalling Flash File System, Version 2.
  3  *
  4  * Copyright © 2001-2007 Red Hat, Inc.
  5  * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
  6  *
  7  * Created by David Woodhouse <dwmw2@infradead.org>
  8  *
  9  * For licensing information, see the file 'LICENCE' in this directory.
 10  *
 11  */
 12 
 13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 14 
 15 #include <linux/kernel.h>
 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 
 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,
 28                         loff_t pos, unsigned len, unsigned flags,
 29                         struct page **pagep, void **fsdata);
 30 static int jffs2_readpage (struct file *filp, struct page *pg);
 31 
 32 int jffs2_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 33 {
 34         struct inode *inode = filp->f_mapping->host;
 35         struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
 36         int ret;
 37 
 38         ret = file_write_and_wait_range(filp, start, end);
 39         if (ret)
 40                 return ret;
 41 
 42         inode_lock(inode);
 43         /* Trigger GC to flush any pending writes for this inode */
 44         jffs2_flush_wbuf_gc(c, inode->i_ino);
 45         inode_unlock(inode);
 46 
 47         return 0;
 48 }
 49 
 50 const struct file_operations jffs2_file_operations =
 51 {
 52         .llseek =       generic_file_llseek,
 53         .open =         generic_file_open,
 54         .read_iter =    generic_file_read_iter,
 55         .write_iter =   generic_file_write_iter,
 56         .unlocked_ioctl=jffs2_ioctl,
 57         .mmap =         generic_file_readonly_mmap,
 58         .fsync =        jffs2_fsync,
 59         .splice_read =  generic_file_splice_read,
 60 };
 61 
 62 /* jffs2_file_inode_operations */
 63 
 64 const struct inode_operations jffs2_file_inode_operations =
 65 {
 66         .get_acl =      jffs2_get_acl,
 67         .set_acl =      jffs2_set_acl,
 68         .setattr =      jffs2_setattr,
 69         .listxattr =    jffs2_listxattr,
 70 };
 71 
 72 const struct address_space_operations jffs2_file_address_operations =
 73 {
 74         .readpage =     jffs2_readpage,
 75         .write_begin =  jffs2_write_begin,
 76         .write_end =    jffs2_write_end,
 77 };
 78 
 79 static int jffs2_do_readpage_nolock (struct inode *inode, struct page *pg)
 80 {
 81         struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
 82         struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
 83         unsigned char *pg_buf;
 84         int ret;
 85 
 86         jffs2_dbg(2, "%s(): ino #%lu, page at offset 0x%lx\n",
 87                   __func__, inode->i_ino, pg->index << PAGE_SHIFT);
 88 
 89         BUG_ON(!PageLocked(pg));
 90 
 91         pg_buf = kmap(pg);
 92         /* FIXME: Can kmap fail? */
 93 
 94         ret = jffs2_read_inode_range(c, f, pg_buf, pg->index << PAGE_SHIFT,
 95                                      PAGE_SIZE);
 96 
 97         if (ret) {
 98                 ClearPageUptodate(pg);
 99                 SetPageError(pg);
100         } else {
101                 SetPageUptodate(pg);
102                 ClearPageError(pg);
103         }
104 
105         flush_dcache_page(pg);
106         kunmap(pg);
107 
108         jffs2_dbg(2, "readpage finished\n");
109         return ret;
110 }
111 
112 int jffs2_do_readpage_unlock(struct inode *inode, struct page *pg)
113 {
114         int ret = jffs2_do_readpage_nolock(inode, pg);
115         unlock_page(pg);
116         return ret;
117 }
118 
119 
120 static int jffs2_readpage (struct file *filp, struct page *pg)
121 {
122         struct jffs2_inode_info *f = JFFS2_INODE_INFO(pg->mapping->host);
123         int ret;
124 
125         mutex_lock(&f->sem);
126         ret = jffs2_do_readpage_unlock(pg->mapping->host, pg);
127         mutex_unlock(&f->sem);
128         return ret;
129 }
130 
131 static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
132                         loff_t pos, unsigned len, unsigned flags,
133                         struct page **pagep, void **fsdata)
134 {
135         struct page *pg;
136         struct inode *inode = mapping->host;
137         struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
138         pgoff_t index = pos >> PAGE_SHIFT;
139         uint32_t pageofs = index << PAGE_SHIFT;
140         int ret = 0;
141 
142         pg = grab_cache_page_write_begin(mapping, index, flags);
143         if (!pg)
144                 return -ENOMEM;
145         *pagep = pg;
146 
147         jffs2_dbg(1, "%s()\n", __func__);
148 
149         if (pageofs > inode->i_size) {
150                 /* Make new hole frag from old EOF to new page */
151                 struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
152                 struct jffs2_raw_inode ri;
153                 struct jffs2_full_dnode *fn;
154                 uint32_t alloc_len;
155 
156                 jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
157                           (unsigned int)inode->i_size, pageofs);
158 
159                 ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
160                                           ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
161                 if (ret)
162                         goto out_page;
163 
164                 mutex_lock(&f->sem);
165                 memset(&ri, 0, sizeof(ri));
166 
167                 ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
168                 ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
169                 ri.totlen = cpu_to_je32(sizeof(ri));
170                 ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));
171 
172                 ri.ino = cpu_to_je32(f->inocache->ino);
173                 ri.version = cpu_to_je32(++f->highest_version);
174                 ri.mode = cpu_to_jemode(inode->i_mode);
175                 ri.uid = cpu_to_je16(i_uid_read(inode));
176                 ri.gid = cpu_to_je16(i_gid_read(inode));
177                 ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
178                 ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
179                 ri.offset = cpu_to_je32(inode->i_size);
180                 ri.dsize = cpu_to_je32(pageofs - inode->i_size);
181                 ri.csize = cpu_to_je32(0);
182                 ri.compr = JFFS2_COMPR_ZERO;
183                 ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
184                 ri.data_crc = cpu_to_je32(0);
185 
186                 fn = jffs2_write_dnode(c, f, &ri, NULL, 0, ALLOC_NORMAL);
187 
188                 if (IS_ERR(fn)) {
189                         ret = PTR_ERR(fn);
190                         jffs2_complete_reservation(c);
191                         mutex_unlock(&f->sem);
192                         goto out_page;
193                 }
194                 ret = jffs2_add_full_dnode_to_inode(c, f, fn);
195                 if (f->metadata) {
196                         jffs2_mark_node_obsolete(c, f->metadata->raw);
197                         jffs2_free_full_dnode(f->metadata);
198                         f->metadata = NULL;
199                 }
200                 if (ret) {
201                         jffs2_dbg(1, "Eep. add_full_dnode_to_inode() failed in write_begin, returned %d\n",
202                                   ret);
203                         jffs2_mark_node_obsolete(c, fn->raw);
204                         jffs2_free_full_dnode(fn);
205                         jffs2_complete_reservation(c);
206                         mutex_unlock(&f->sem);
207                         goto out_page;
208                 }
209                 jffs2_complete_reservation(c);
210                 inode->i_size = pageofs;
211                 mutex_unlock(&f->sem);
212         }
213 
214         /*
215          * Read in the page if it wasn't already present. Cannot optimize away
216          * the whole page write case until jffs2_write_end can handle the
217          * case of a short-copy.
218          */
219         if (!PageUptodate(pg)) {
220                 mutex_lock(&f->sem);
221                 ret = jffs2_do_readpage_nolock(inode, pg);
222                 mutex_unlock(&f->sem);
223                 if (ret)
224                         goto out_page;
225         }
226         jffs2_dbg(1, "end write_begin(). pg->flags %lx\n", pg->flags);
227         return ret;
228 
229 out_page:
230         unlock_page(pg);
231         put_page(pg);
232         return ret;
233 }
234 
235 static int jffs2_write_end(struct file *filp, struct address_space *mapping,
236                         loff_t pos, unsigned len, unsigned copied,
237                         struct page *pg, void *fsdata)
238 {
239         /* Actually commit the write from the page cache page we're looking at.
240          * For now, we write the full page out each time. It sucks, but it's simple
241          */
242         struct inode *inode = mapping->host;
243         struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
244         struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
245         struct jffs2_raw_inode *ri;
246         unsigned start = pos & (PAGE_SIZE - 1);
247         unsigned end = start + copied;
248         unsigned aligned_start = start & ~3;
249         int ret = 0;
250         uint32_t writtenlen = 0;
251 
252         jffs2_dbg(1, "%s(): ino #%lu, page at 0x%lx, range %d-%d, flags %lx\n",
253                   __func__, inode->i_ino, pg->index << PAGE_SHIFT,
254                   start, end, pg->flags);
255 
256         /* We need to avoid deadlock with page_cache_read() in
257            jffs2_garbage_collect_pass(). So the page must be
258            up to date to prevent page_cache_read() from trying
259            to re-lock it. */
260         BUG_ON(!PageUptodate(pg));
261 
262         if (end == PAGE_SIZE) {
263                 /* When writing out the end of a page, write out the
264                    _whole_ page. This helps to reduce the number of
265                    nodes in files which have many short writes, like
266                    syslog files. */
267                 aligned_start = 0;
268         }
269 
270         ri = jffs2_alloc_raw_inode();
271 
272         if (!ri) {
273                 jffs2_dbg(1, "%s(): Allocation of raw inode failed\n",
274                           __func__);
275                 unlock_page(pg);
276                 put_page(pg);
277                 return -ENOMEM;
278         }
279 
280         /* Set the fields that the generic jffs2_write_inode_range() code can't find */
281         ri->ino = cpu_to_je32(inode->i_ino);
282         ri->mode = cpu_to_jemode(inode->i_mode);
283         ri->uid = cpu_to_je16(i_uid_read(inode));
284         ri->gid = cpu_to_je16(i_gid_read(inode));
285         ri->isize = cpu_to_je32((uint32_t)inode->i_size);
286         ri->atime = ri->ctime = ri->mtime = cpu_to_je32(JFFS2_NOW());
287 
288         /* In 2.4, it was already kmapped by generic_file_write(). Doesn't
289            hurt to do it again. The alternative is ifdefs, which are ugly. */
290         kmap(pg);
291 
292         ret = jffs2_write_inode_range(c, f, ri, page_address(pg) + aligned_start,
293                                       (pg->index << PAGE_SHIFT) + aligned_start,
294                                       end - aligned_start, &writtenlen);
295 
296         kunmap(pg);
297 
298         if (ret) {
299                 /* There was an error writing. */
300                 SetPageError(pg);
301         }
302 
303         /* Adjust writtenlen for the padding we did, so we don't confuse our caller */
304         writtenlen -= min(writtenlen, (start - aligned_start));
305 
306         if (writtenlen) {
307                 if (inode->i_size < pos + writtenlen) {
308                         inode->i_size = pos + writtenlen;
309                         inode->i_blocks = (inode->i_size + 511) >> 9;
310 
311                         inode->i_ctime = inode->i_mtime = ITIME(je32_to_cpu(ri->ctime));
312                 }
313         }
314 
315         jffs2_free_raw_inode(ri);
316 
317         if (start+writtenlen < end) {
318                 /* generic_file_write has written more to the page cache than we've
319                    actually written to the medium. Mark the page !Uptodate so that
320                    it gets reread */
321                 jffs2_dbg(1, "%s(): Not all bytes written. Marking page !uptodate\n",
322                         __func__);
323                 SetPageError(pg);
324                 ClearPageUptodate(pg);
325         }
326 
327         jffs2_dbg(1, "%s() returning %d\n",
328                   __func__, writtenlen > 0 ? writtenlen : ret);
329         unlock_page(pg);
330         put_page(pg);
331         return writtenlen > 0 ? writtenlen : ret;
332 }
333 

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