| blob | 273a3c9cc5b0f03eea98934fdc18f121346d7f3a |
1 /*
2 * JFFS -- Journaling Flash File System, Linux implementation.
3 *
4 * Copyright (C) 1999, 2000 Axis Communications, Inc.
5 *
6 * Created by Finn Hakansson <finn@axis.com>.
7 *
8 * This is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * $Id: intrep.c,v 1.102 2001/09/23 23:28:36 dwmw2 Exp $
14 *
15 * Ported to Linux 2.3.x and MTD:
16 * Copyright (C) 2000 Alexander Larsson (alex@cendio.se), Cendio Systems AB
17 *
18 */
20 /* This file contains the code for the internal structure of the
21 Journaling Flash File System, JFFS. */
23 /*
24 * Todo list:
25 *
26 * memcpy_to_flash() and memcpy_from_flash() functions.
27 *
28 * Implementation of hard links.
29 *
30 * Organize the source code in a better way. Against the VFS we could
31 * have jffs_ext.c, and against the block device jffs_int.c.
32 * A better file-internal organization too.
33 *
34 * A better checksum algorithm.
35 *
36 * Consider endianness stuff. ntohl() etc.
37 *
38 * Are we handling the atime, mtime, ctime members of the inode right?
39 *
40 * Remove some duplicated code. Take a look at jffs_write_node() and
41 * jffs_rewrite_data() for instance.
42 *
43 * Implement more meaning of the nlink member in various data structures.
44 * nlink could be used in conjunction with hard links for instance.
45 *
46 * Better memory management. Allocate data structures in larger chunks
47 * if possible.
48 *
49 * If too much meta data is stored, a garbage collect should be issued.
50 * We have experienced problems with too much meta data with for instance
51 * log files.
52 *
53 * Improve the calls to jffs_ioctl(). We would like to retrieve more
54 * information to be able to debug (or to supervise) JFFS during run-time.
55 *
56 */
58 #include <linux/config.h>
59 #include <linux/types.h>
60 #include <linux/slab.h>
61 #include <linux/jffs.h>
62 #include <linux/fs.h>
63 #include <linux/stat.h>
64 #include <linux/pagemap.h>
65 #include <asm/semaphore.h>
66 #include <asm/byteorder.h>
67 #include <linux/smp_lock.h>
68 #include <linux/time.h>
69 #include <linux/ctype.h>
76 #if defined(JFFS_MEMORY_DEBUG) && JFFS_MEMORY_DEBUG
84 #endif
89 #if CONFIG_JFFS_FS_VERBOSE > 0
90 static __u8
92 {
94 __u8 ret;
101 }
104 }
106 static void
108 {
118 }
122 }
125 }
126 }
128 /* Print empty space */
132 }
135 }
136 }
142 }
145 }
146 }
149 }
150 }
152 #endif
154 #define flash_safe_acquire(arg)
155 #define flash_safe_release(arg)
158 static int
161 {
171 }
173 }
176 static __u32
178 {
180 __u32 ret;
187 }
190 }
193 static int
196 {
206 }
208 }
211 static int
214 {
225 }
226 /* Not implemented writev. Repeatedly use write - on the not so
227 unreasonable assumption that the mtd driver doesn't care how
228 many write cycles we use. */
238 }
239 /* If res is non-zero, retlen_a is undefined, but we don't
240 care because in that case it's not going to be
241 returned anyway.
242 */
245 }
247 }
250 static int
253 {
257 /* fill up pattern */
262 /* write as many 64-byte chunks as we can */
268 }
270 /* and the rest */
276 }
279 static void
281 {
287 }
290 static int
293 {
296 wait_queue_head_t wait_q;
310 /* FIXME: Use TASK_INTERRUPTIBLE and deal with being interrupted */
323 }
331 }
333 /* This routine calculates checksums in JFFS. */
334 __u32
336 {
341 }
344 }
347 int
349 {
355 /* Allocate read buffer */
360 }
361 /* Loop until checksum done */
363 /* Get amount of data to read */
366 else
369 /* Perform flash read */
373 /* Compute checksum */
377 /* Update pointer and size */
380 }
382 /* Free read buffer */
385 /* Return result */
389 }
392 {
393 // down(&fmc->wlock);
394 }
397 {
398 // up(&fmc->wlock);
399 }
402 /* Create and initialize a new struct jffs_file. */
406 {
410 GFP_KERNEL))) {
413 }
414 no_jffs_file++;
423 }
426 /* Build a control block for the file system. */
429 {
439 }
447 }
453 }
458 fail_fminit:
460 fail_hash:
464 fail_control:
468 }
471 /* Clean up all data structures associated with the file system. */
472 void
474 {
480 }
487 }
489 /* Free all files and nodes. */
495 }
500 }
503 /* This function adds a virtual root node to the in-RAM representation.
504 Called by jffs_build_fs(). */
505 static int
507 {
515 GFP_KERNEL))) {
517 }
518 no_jffs_file++;
521 no_jffs_file--;
523 }
537 }
540 /* This is where the file system is built and initialized. */
541 int
543 {
551 }
556 /* scan_flash() wants us to try once more. A flipping
557 bits sector was detect in the middle of the scan flash.
558 Clean up old allocated memory before going in.
559 */
565 }
571 }
574 }
575 }
577 /* Add a virtual root node if no one exists. */
581 }
582 }
590 }
594 }
596 /* Remove deleted nodes. */
600 }
601 /* Remove redundant nodes. (We are not interested in the
602 return value in this case.) */
604 /* Try to build a tree from all the nodes. */
608 }
609 /* Compute the sizes of all files in the filesystem. Adjust if
610 necessary. */
614 }
623 jffs_build_fs_fail:
629 /*
630 This checks for sectors that were being erased in their previous
631 lifetimes and for some reason or the other (power fail etc.),
632 the erase cycles never completed.
633 As the flash array would have reverted back to read status,
634 these sectors are detected by the symptom of the "flipping bits",
635 i.e. bits being read back differently from the same location in
636 flash if read multiple times.
637 The only solution to this is to re-erase the entire
638 sector.
639 Unfortunately detecting "flipping bits" is not a simple exercise
640 as a bit may be read back at 1 or 0 depending on the alignment
641 of the stars in the universe.
642 The level of confidence is in direct proportion to the number of
643 scans done. By power fail testing I (Vipin) have been able to
644 proove that reading twice is not enough.
645 Maybe 4 times? Change NUM_REREADS to a higher number if you want
646 a (even) higher degree of confidence in your mount process.
647 A higher number would of course slow down your mount.
648 */
653 usually set to kernel page size */
662 __u32 offset;
667 /* Allocate read buffers */
676 }
678 CHECK_NEXT:
693 /* buffers MUST match, double word for word! */
696 ){
697 /* flipping bits detected, time to erase sector */
698 /* This will help us log some statistics etc. */
706 /* calculate start of present sector */
710 offset));
723 offset));
724 /* skip ahead to the next sector */
728 }
729 }
730 }
731 }
733 }
735 returnBack:
739 D2(printk("check_partly_erased_sector():Done checking all sectors till offset 0x%x for flipping bits.\n",
748 /* Scan the whole flash memory in order to find all nodes in the
749 file systems. */
750 static int
752 {
757 __u32 checksum;
758 __u8 tmp_accurate;
759 __u16 tmp_chksum;
760 __u32 deleted_file;
762 loff_t start;
763 loff_t test_start;
767 __u32 offset;
769 __u32 free_chunk_size1;
770 __u32 free_chunk_size2;
775 free blocks found. This is NOT allowed
776 by the current jffs design.
777 */
779 of how much free space was rejected and
780 marked dirty
781 */
788 /*
789 check and make sure that any sector does not suffer
790 from the "partly erased, bit flipping syndrome" (TM Vipin :)
791 If so, offending sectors will be erased.
792 */
797 }
799 /* Allocate read buffer */
804 }
806 /* Start the scan. */
810 /* Remember the position from where we started this scan. */
815 /* We have found 0xffffffff at this position. We have to
816 scan the rest of the flash till the end or till
817 something else than 0xffffffff is found.
818 Keep going till we do not find JFFS_EMPTY_BITMASK
819 anymore */
835 JFFS_EMPTY_BITMASK)
837 }
840 else
842 }
847 /* If some free space ends in the middle of a sector,
848 treat it as dirty rather than clean.
849 This is to handle the case where one thread
850 allocated space for a node, but didn't get to
851 actually _write_ it before power was lost, leaving
852 a gap in the log. Shifting all node writes into
853 a single kernel thread will fix the original problem.
854 */
856 /* If there was free space in previous
857 sectors, don't mark that dirty too -
858 only from the beginning of this sector
859 (or from start)
860 */
866 /* free space started in the previous sector! */
871 /*
872 Count it in if we are still under NUMFREEALLOWED *and* it is
873 at least 1 erase sector in length. This will keep us from
874 picking any little ole' space as "free".
875 */
884 /* below, space from "start" to "pos" will be marked dirty. */
887 /* Being in here means that we have found at least an entire
888 erase sector size of free space ending on a sector boundary.
889 Keep track of free spaces accepted.
890 */
891 num_free_space++;
893 num_free_spc_not_accp++;
899 }
901 }
909 /* "Flipping bits" detected. This means that our scan for them
910 did not catch this offset. See check_partly_erased_sectors() for
911 more info.
912 */
919 /* calculate start of present sector */
923 offset));
935 }
940 }
942 /* Being in here means that we have found free space that ends on an erase sector
943 boundary.
944 Count it in if we are still under NUMFREEALLOWED *and* it is at least 1 erase
945 sector in length. This will keep us from picking any little ole' space as "free".
946 */
949 /* We really don't do anything to mark space as free, except *not*
950 mark it dirty and just advance the "pos" location pointer.
951 It will automatically be picked up as free space.
952 */
953 num_free_space++;
957 num_free_spc_not_accp++;
963 /* Mark this space as dirty. We already have our free space. */
968 }
970 }
975 }
979 /* We have found 0x00000000 at this position. Scan as far
980 as possible to find out how much is dirty. */
993 /* We have probably found a new raw inode. */
997 bad_inode:
998 /* We're f*cked. This is not solved yet. We have
999 to scan for the magic pattern. */
1001 "bad inode: "
1010 /* handle these in the main switch() loop */
1015 }
1016 }
1018 cont_scan:
1019 /* First, mark as dirty the region
1020 which really does contain crap. */
1023 NULL);
1028 /* We have found the beginning of an inode. Create a
1029 node for it unless there already is one available. */
1032 /* Free read buffer */
1035 /* Release the flash device */
1039 }
1041 }
1043 /* Read the next raw inode. */
1048 /* When we compute the checksum for the inode, we never
1049 count the 'accurate' or the 'checksum' fields. */
1065 "checksum = %u, "
1071 /* Reuse this unused struct jffs_node. */
1073 }
1075 /* Check the raw inode read so far. Start with the
1076 maximum length of the filename. */
1081 }
1089 }
1091 /* The node's data segment should not exceed a
1092 certain length. */
1098 }
1102 /* This shouldn't be necessary because a node that
1103 violates the flash boundaries shouldn't be written
1104 in the first place. */
1107 }
1109 /* Read the name. */
1120 "checksum = %u, "
1125 /* Reuse this unused struct jffs_node. */
1127 }
1130 }
1131 }
1133 /* Read the data, if it exists, in order to be sure it
1134 matches the checksum. */
1138 }
1143 /* Reuse this unused struct jffs_node. */
1145 }
1151 "checksum = %u, "
1156 /* Reuse this unused struct jffs_node. */
1158 }
1159 }
1161 check_node:
1163 /* Remember the highest inode number in the whole file
1164 system. This information will be used when assigning
1165 new files new inode numbers. */
1168 }
1175 /* Compute the offset to the actual data in the
1176 on-flash node. */
1177 node->fm_offset
1183 node);
1189 /* Free read buffer */
1192 /* Release the flash device */
1196 }
1202 }
1207 GFP_KERNEL);
1213 /* Release the flash device */
1216 /* Free read buffer */
1220 }
1225 }
1228 }
1234 /* Reuse this unused struct jffs_node. */
1235 }
1236 }
1241 }
1244 /* Free read buffer */
1250 }
1252 /* Return happy */
1256 /* This is to trap the "free size accounting screwed error. */
1268 Mounting this screwed up f/s will screw us up anyway.
1269 */
1270 }
1276 /* Insert any kind of node into the file system. Take care of data
1277 insertions and deletions. Also remove redundant information. The
1278 memory allocated for the `name' is regarded as "given away" in the
1279 caller's perspective. */
1280 int
1284 {
1293 /* If there doesn't exist an associated jffs_file, then
1294 create, initialize and insert one into the file system. */
1298 }
1301 }
1309 /* Now insert the node at the correct position into the file's
1310 version list. */
1312 /* This is the first node. */
1325 }
1328 /* Insert at the end of the list. I.e. this node is the
1329 newest one so far. */
1343 }
1345 /* Insert at the bottom of the list. */
1352 }
1353 }
1357 /* Search for the insertion position starting from
1358 the tail (newest node). */
1367 }
1369 }
1372 }
1373 }
1374 }
1376 /* Deletion is irreversible. If any 'deleted' node is ever
1377 written, the file is deleted */
1381 /* Perhaps update the name. */
1386 }
1388 GFP_KERNEL))) {
1390 }
1397 }
1404 }
1405 /* Once upon a time, we would call jffs_possibly_delete_file()
1406 here. That causes an oops if someone's still got the file
1407 open, so now we only do it in jffs_delete_inode()
1408 -- dwmw2
1409 */
1412 }
1419 }
1425 /* Unlink a jffs_node from the version list it is in. */
1429 {
1434 }
1439 }
1440 }
1443 /* Unlink a jffs_node from the range list it is in. */
1446 {
1449 }
1452 }
1455 }
1458 }
1459 }
1462 /* Function used by jffs_remove_redundant_nodes() below. This function
1463 classifies what kind of information a node adds to a file. */
1466 {
1471 }
1474 }
1476 }
1479 /* Remove redundant nodes from a file. Mark the on-flash memory
1480 as dirty. */
1481 int
1483 {
1487 __u8 newest_type;
1488 __u8 mod_type;
1493 }
1495 /* What does the `newest_node' modify? */
1501 newest_type));
1503 /* Traverse the file's nodes and determine which of them that are
1504 superfluous. Yeah, this might look very complex at first
1505 glance but it is actually very simple. */
1511 && (mod_type
1515 /* Yes, this node is redundant. Remove it. */
1517 "Removing node: ino: %u, version: %u, "
1519 mod_type));
1524 }
1527 }
1528 }
1531 }
1534 /* Insert a file into the hash table. */
1535 int
1537 {
1544 }
1547 /* Insert a file into the file system tree. */
1548 int
1550 {
1563 }
1569 }
1570 }
1575 }
1579 }
1582 /* Remove a file from the hash table. */
1583 int
1585 {
1591 }
1594 /* Just remove the file from the parent's children. Don't free
1595 any memory. */
1596 int
1598 {
1604 }
1608 }
1611 }
1613 }
1616 /* Find a file with its inode number. */
1619 {
1633 );
1635 }
1638 );
1640 }
1643 /* Find a file in a directory. We are comparing the names. */
1646 {
1656 }
1657 }
1661 }
1667 }
1672 }
1673 });
1676 }
1679 /* Write a raw inode that takes up a certain amount of space in the flash
1680 memory. At the end of the flash device, there is often space that is
1681 impossible to use. At these times we want to mark this space as not
1682 used. In the cases when the amount of space is greater or equal than
1683 a struct jffs_raw_inode, we write a "dummy node" that takes up this
1684 space. The space after the raw inode, if it exists, is left as it is.
1685 Since this space after the raw inode contains JFFS_EMPTY_BITMASK bytes,
1686 we can compute the checksum of it; we don't have to manipulate it any
1687 further.
1689 If the space left on the device is less than the size of a struct
1690 jffs_raw_inode, this space is filled with JFFS_DIRTY_BITMASK bytes.
1691 No raw inode is written this time. */
1692 static int
1694 {
1709 raw_inode.chksum
1720 }
1721 }
1726 }
1730 }
1733 /* Write a raw inode, possibly its name and possibly some data. */
1734 int
1740 {
1746 __u32 pos;
1757 /* If this node isn't something that will eventually let
1758 GC free even more space, then don't allow it unless
1759 there's at least max_chunk_size space still available
1760 */
1765 /* Fire the retrorockets and shoot the fruiton torpedoes, sir! */
1770 });
1775 });
1780 total_size));
1784 retry:
1789 /* Deadlocks suck. */
1795 }
1797 /* First try to allocate some flash memory. */
1801 /* Just out of space. GC and try again */
1805 total_size));
1807 }
1814 }
1817 }
1825 }
1828 /* The jffs_fm struct that we got is not good enough.
1829 Make that space dirty and try again */
1837 }
1839 }
1845 });
1849 /* Increment the version number here. We can't let the caller
1850 set it beforehand, because we might have had to do GC on a node
1851 of this file - and we'd end up reusing version numbers.
1852 */
1855 D1(printk (KERN_NOTICE "jffs_write_node(): setting version of %s to %d\n", f->name, raw_inode->version));
1857 /* if the file was deleted, set the deleted bit in the raw inode */
1860 }
1862 /* Compute the checksum for the data and name chunks. */
1866 /* The checksum is calculated without the chksum and accurate
1867 fields so set them to zero first. */
1878 /* The actual raw JFFS node */
1883 /* Get name and size if there is one */
1887 iovec_cnt++;
1891 /* Add some extra padding if necessary */
1895 iovec_cnt++;
1896 }
1897 }
1899 /* Get data and size if there is any */
1903 iovec_cnt++;
1904 /* No need to pad this because we're not actually putting
1905 anything after it.
1906 */
1907 }
1916 }
1926 /* Read data from the node and write it to the buffer. 'node_offset'
1927 is how much we have read from this particular node before and which
1928 shouldn't be read again. 'max_size' is how much space there is in
1929 the buffer. */
1930 static int
1933 {
1937 __u32 r;
1951 }
1954 /* Read data from the file's nodes. Write the data to the buffer
1955 'buf'. 'read_offset' tells how much data we should skip. */
1956 int
1958 __u32 size)
1959 {
1972 }
1974 /* First find the node to read data from. */
1981 }
1984 }
1985 }
1987 /* "Cats are living proof that not everything in nature
1988 has to be useful."
1989 - Garrison Keilor ('97) */
1991 /* Fill the buffer. */
1995 /* This node does not refer to real data. */
1999 }
2001 node_offset,
2004 }
2008 }
2011 }
2014 /* Used for traversing all nodes in the hash table. */
2015 int
2017 {
2025 /* We need a reference to the next file in the
2026 list because `func' might remove the current
2027 file `f'. */
2033 }
2034 }
2037 }
2040 /* Free all nodes associated with a file. */
2041 int
2043 {
2055 }
2057 }
2060 /* Free a file and its name. */
2061 int
2063 {
2070 }
2072 no_jffs_file--;
2074 }
2076 long
2078 {
2080 }
2082 /* See if a file is deleted. If so, mark that file's nodes as obsolete. */
2083 int
2085 {
2094 });
2097 /* First try to remove all older versions. Commence with
2098 the oldest node. */
2102 }
2105 }
2106 }
2107 /* Unlink the file from the filesystem. */
2110 }
2114 }
2116 }
2119 /* Used in conjunction with jffs_foreach_file() to count the number
2120 of files in the file system. */
2121 int
2123 {
2125 }
2128 /* Build up a file's range list from scratch by going through the
2129 version list. */
2130 int
2132 {
2140 }
2142 }
2145 /* Remove an amount of data from a file. If this amount of data is
2146 zero, that could mean that a node should be split in two parts.
2147 We remove or change the appropriate nodes in the lists.
2149 Starting offset of area to be removed is node->data_offset,
2150 and the length of the area is in node->removed_size. */
2151 static int
2153 {
2165 /* A simple append; nothing to remove or no node to split. */
2167 }
2169 /* Find the node where we should begin the removal. */
2173 }
2174 }
2176 /* If there's no data in the file there's no data to
2177 remove either. */
2179 }
2182 /* XXX: Not implemented yet. */
2185 }
2187 /* See if the node has to be split into two parts. */
2189 /* Do the split. */
2197 }
2212 }
2215 }
2221 }
2224 }
2225 /* A very interesting can of worms. */
2233 }
2236 }
2238 /* No. No need to split the node. Just remove
2239 the end of the node. */
2245 }
2246 }
2248 /* Remove as many nodes as necessary. */
2260 }
2265 }
2272 }
2273 }
2275 /* Adjust the following nodes' information about offsets etc. */
2279 }
2282 /* It's possible that the removed_size is in fact
2283 * greater than the amount of data we actually thought
2284 * were present in the first place - some of the nodes
2285 * which this node originally obsoleted may already have
2286 * been deleted from the flash by subsequent garbage
2287 * collection.
2288 *
2289 * If this is the case, don't let f->size go negative.
2290 * Bad things would happen :)
2291 */
2295 }
2301 /* Insert some data into a file. Prior to the call to this function,
2302 jffs_delete_data should be called. */
2303 static int
2305 {
2310 /* Find the position where we should insert data. */
2311 retry:
2313 /* A simple append. This is the most common operation. */
2318 }
2323 }
2324 }
2326 /* Trying to insert data into the middle of the file. This
2327 means no problem because jffs_delete_data() has already
2328 prepared the range list for us. */
2331 /* Find the correct place for the insertion and then insert
2332 the node. */
2340 }
2343 }
2347 }
2351 "Couldn't find a place to insert "
2354 });
2355 }
2357 /* Adjust later nodes' offsets etc. */
2362 }
2364 }
2366 /* Okay. This is tricky. This means that we want to insert
2367 data at a place that is beyond the limits of the file as
2368 it is constructed right now. This is actually a common
2369 event that for instance could occur during the mounting
2370 of the file system if a large file have been truncated,
2371 rewritten and then only partially garbage collected. */
2375 /* We need a place holder for the data that is missing in
2376 front of this insertion. This "virtual node" will not
2377 be associated with any space on the flash device. */
2381 }
2397 /* Are there any data at all in the file yet? */
2399 virtual_node->data_offset
2402 virtual_node->data_size
2406 }
2412 }
2417 /* Insert this virtual node in the version list as well. */
2423 virtual_node->version_prev
2425 }
2428 }
2431 }
2432 }
2436 /* Make a new try to insert the node. */
2438 }
2442 }
2445 /* A new node (with data) has been added to the file and now the range
2446 list has to be modified. */
2447 static int
2449 {
2457 /* data_offset == X */
2458 /* data_size == 0 */
2459 /* remove_size == 0 */
2460 }
2462 /* data_offset == X */
2463 /* data_size == 0 */
2464 /* remove_size != 0 */
2467 }
2468 }
2469 }
2471 /* data_offset == X */
2472 /* data_size != 0 */
2473 /* remove_size == Y */
2476 }
2479 }
2480 }
2482 }
2485 /* Print the contents of a node. */
2486 void
2488 {
2504 }
2507 /* Print the contents of a raw inode. */
2508 void
2510 {
2540 }
2543 /* Print the contents of a file. */
2544 int
2546 {
2564 });
2582 }
2585 void
2587 {
2599 }
2600 }
2601 }
2604 void
2606 {
2613 }
2618 }
2630 }
2631 }
2634 }
2637 #if defined(JFFS_MEMORY_DEBUG) && JFFS_MEMORY_DEBUG
2638 void
2640 {
2653 }
2654 #endif
2657 /* Rewrite `size' bytes, and begin at `node'. */
2658 int
2660 {
2666 __u32 pos;
2667 __u32 pos_dchksum;
2668 __u32 total_name_size;
2669 __u32 total_data_size;
2670 __u32 total_size;
2676 /* Create and initialize the new node. */
2681 }
2692 retry:
2702 }
2704 /* The jffs_fm struct that we got is not big enough. */
2705 /* This should never happen, because we deal with this case
2706 in jffs_garbage_collect_next().*/
2707 printk(KERN_WARNING "jffs_rewrite_data(): Allocated node is too small (%d bytes of %d)\n", fm->size, total_size);
2713 }
2719 }
2722 /* Initialize the raw inode. */
2765 }
2768 /* Write the name to the flash memory. */
2782 }
2785 }
2787 /* Write the data. */
2796 }
2806 "jffs_read_data() "
2809 }
2816 "Write error during rewrite. "
2819 }
2824 }
2827 }
2834 /* Add the checksum. */
2846 }
2848 /* Now make the file system aware of the newly written node. */
2857 /* jffs_garbage_collect_next implements one step in the garbage collect
2858 process and is often called multiple times at each occasion of a
2859 garbage collect. */
2861 int
2863 {
2868 __u32 size;
2869 __u32 data_size;
2870 __u32 total_name_size;
2871 __u32 extra_available;
2872 __u32 space_needed;
2876 /* Get the oldest node in the flash. */
2885 });
2887 /* Find its corresponding file too. */
2892 "No file to garbage collect! "
2894 /* FIXME: Free the offending node and recover. */
2897 }
2899 /* We always write out the name. Theoretically, we don't need
2900 to, but for now it's easier - because otherwise we'd have
2901 to keep track of how many times the current name exists on
2902 the flash and make sure it never reaches zero.
2904 The current approach means that would be possible to cause
2905 the GC to end up eating its tail by writing lots of nodes
2906 with no name for it to garbage-collect. Hence the change in
2907 inode.c to write names with _every_ node.
2909 It sucks, but it _should_ work.
2910 */
2918 /* Compute how many data it's possible to rewrite at the moment. */
2921 /* And from that, the total size of the chunk we want to write */
2925 /* If that's more than max_chunk_size, reduce it accordingly */
2930 }
2932 /* If we're asking to take up more space than free_chunk_size1
2933 but we _could_ fit in it, shrink accordingly.
2934 */
2939 /* The space left is too small to be of any
2940 use really. */
2947 "jffs_garbage_collect_next: "
2948 "Failed to allocate `dirty' "
2952 }
2957 }
2965 }
2968 /* Calculate the amount of space needed to hold the nodes
2969 which are remaining in the tail */
2972 /* From that, calculate how much 'extra' space we can use to
2973 increase the size of the node we're writing from the size
2974 of the node we're obsoleting
2975 */
2977 /* If we've gone below min_free_size for some reason,
2978 don't fuck up. This is why we have
2979 min_free_size > sector_size. Whinge about it though,
2980 just so I can convince myself my maths is right.
2981 */
2988 }
2990 /* Check that we don't use up any more 'extra' space than
2991 what's available */
3005 };
3020 }
3022 jffs_garbage_collect_next_end:
3028 /* If an obsolete node is partly going to be erased due to garbage
3029 collection, the part that isn't going to be erased must be filled
3030 with zeroes so that the scan of the flash will work smoothly next
3031 time. (The data in the file could for instance be a JFFS image
3032 which could cause enormous confusion during a scan of the flash
3033 device if we didn't do this.)
3034 There are two phases in this procedure: First, the clearing of
3035 the name and data parts of the node. Second, possibly also clearing
3036 a part of the raw inode as well. If the box is power cycled during
3037 the first phase, only the checksum of this node-to-be-cleared-at-
3038 the-end will be wrong. If the box is power cycled during, or after,
3039 the clearing of the raw inode, the information like the length of
3040 the name and data parts are zeroed. The next time the box is
3041 powered up, the scanning algorithm manages this faulty data too
3042 because:
3044 - The checksum is invalid and thus the raw inode must be discarded
3045 in any case.
3046 - If the lengths of the data part or the name part are zeroed, the
3047 scanning just continues after the raw inode. But after the inode
3048 the scanning procedure just finds zeroes which is the same as
3049 dirt.
3051 So, in the end, this could never fail. :-) Even if it does fail,
3052 the scanning algorithm should manage that too. */
3054 static int
3056 {
3059 __u32 zero_offset;
3060 __u32 zero_size;
3061 __u32 zero_offset_data;
3062 __u32 zero_size_data;
3068 }
3070 /* Where and how much shall we clear? */
3074 /* Do we have to clear the raw_inode explicitly? */
3078 }
3080 /* First, clear the name and data fields. */
3087 /* Should we clear a part of the raw inode? */
3089 /* I guess it is ok to clear the raw inode in this order. */
3092 cutting_raw_inode);
3094 }
3099 /* Try to erase as much as possible of the dirt in the flash memory. */
3100 long
3102 {
3106 __u32 offset;
3116 }
3121 }
3127 }
3131 /* Now, let's try to do the erase. */
3137 /* XXX: Here we should allocate this area as dirty
3138 with jffs_fmalloced or something similar. Now
3139 we just report the error. */
3141 }
3143 #if 0
3144 /* Check if the erased sectors really got erased. */
3145 {
3146 __u32 pos;
3147 __u32 end;
3164 }
3165 }
3171 }
3173 /* XXX: Here we should allocate the memory
3174 with jffs_fmalloced() in order to prevent
3175 JFFS from using this area accidentally. */
3177 }
3178 }
3179 #endif
3181 /* Update the flash memory data structures. */
3185 }
3188 /* There are different criteria that should trigger a garbage collect:
3190 1. There is too much dirt in the memory.
3191 2. The free space is becoming small.
3192 3. There are many versions of a node.
3194 The garbage collect should always be done in a manner that guarantees
3195 that future garbage collects cannot be locked. E.g. Rewritten chunks
3196 should not be too large (span more than one sector in the flash memory
3197 for exemple). Of course there is a limit on how intelligent this garbage
3198 collection can be. */
3201 int
3203 {
3208 D2(printk("***jffs_garbage_collect_now(): fmc->dirty_size = %u, fmc->free_size = 0x%x\n, fcs1=0x%x, fcs2=0x%x",
3212 // down(&fmc->gclock);
3214 /* If it is possible to garbage collect, do so. */
3226 }
3231 /* Argh */
3235 }
3238 /* Actually, we _may_ have been able to free some,
3239 * if there are many overlapping nodes which aren't
3240 * actually marked dirty because they still have
3241 * some valid data in each.
3242 */
3245 }
3247 /* Let's dare to make a garbage collect. */
3250 "has gone seriously wrong "
3253 }
3257 }
3259 gc_end:
3260 // up(&fmc->gclock);
3266 });
3275 /* Determine if it is reasonable to start garbage collection.
3276 We start a gc pass if either:
3277 - The number of free bytes < MIN_FREE_BYTES && at least one
3278 block is dirty, OR
3279 - The number of dirty bytes > MAX_DIRTY_BYTES
3280 */
3282 {
3286 /* If there's not enough dirty space to free a block, there's no point. */
3290 }
3291 #if 1
3292 /* If there is too much RAM used by the various structures, GC */
3293 if (jffs_get_node_inuse() > (c->fmc->used_size/c->fmc->max_chunk_size * 5 + jffs_get_file_count() * 2 + 50)) {
3294 /* FIXME: Provide proof that this test can be satisfied. We
3295 don't want a filesystem doing endless GC just because this
3296 condition cannot ever be false.
3297 */
3300 }
3301 #endif
3302 /* If there are fewer free bytes than the threshold, GC */
3306 }
3307 /* If there are more dirty bytes than the threshold, GC */
3311 }
3312 /* FIXME: What about the "There are many versions of a node" condition? */
3315 }
3319 {
3320 /* NOTE: We rely on the fact that we have the BKL here.
3321 * Otherwise, the gc_task could go away between the check
3322 * and the wake_up_process()
3323 */
3326 }
3329 /* Kernel threads take (void *) as arguments. Thus we pass
3330 the jffs_control data as a (void *) and then cast it. */
3331 int
3333 {
3347 siginitsetinv (¤t->blocked, sigmask(SIGHUP) | sigmask(SIGKILL) | sigmask(SIGSTOP) | sigmask(SIGCONT));
3355 /* See if we need to start gc. If we don't, go to sleep.
3357 Current implementation is a BAD THING(tm). If we try
3358 to unmount the FS, the unmount operation will sleep waiting
3359 for this thread to exit. We need to arrange to send it a
3360 sig before the umount process sleeps.
3361 */
3367 on immediately - we're a low priority
3368 background task. */
3370 /* Put_super will send a SIGKILL and then wait on the sem.
3371 */
3373 siginfo_t info;
3391 }
3392 }
3407 }
3413 /* Argh. Might as well commit suicide. */
3416 // panic()
3418 }
3420 /* Let's dare to make a garbage collect. */
3423 "has gone seriously wrong "
3425 }
3427 gc_end: