blob: 0f7f88d067adad67b0d846fc9ebfb2f7109f3202 [file] [log] [blame]
Tom Zanussie82894f2005-09-06 15:16:30 -07001/*
2 * VFS-related code for RelayFS, a high-speed data relay filesystem.
3 *
4 * Copyright (C) 2003-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
5 * Copyright (C) 2003-2005 - Karim Yaghmour <karim@opersys.com>
6 *
7 * Based on ramfs, Copyright (C) 2002 - Linus Torvalds
8 *
9 * This file is released under the GPL.
10 */
11
12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/mount.h>
15#include <linux/pagemap.h>
16#include <linux/init.h>
17#include <linux/string.h>
18#include <linux/backing-dev.h>
19#include <linux/namei.h>
20#include <linux/poll.h>
21#include <linux/relayfs_fs.h>
22#include "relay.h"
23#include "buffers.h"
24
25#define RELAYFS_MAGIC 0xF0B4A981
26
27static struct vfsmount * relayfs_mount;
28static int relayfs_mount_count;
29static kmem_cache_t * relayfs_inode_cachep;
30
31static struct backing_dev_info relayfs_backing_dev_info = {
32 .ra_pages = 0, /* No readahead */
33 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
34};
35
36static struct inode *relayfs_get_inode(struct super_block *sb, int mode,
37 struct rchan *chan)
38{
39 struct rchan_buf *buf = NULL;
40 struct inode *inode;
41
42 if (S_ISREG(mode)) {
43 BUG_ON(!chan);
44 buf = relay_create_buf(chan);
45 if (!buf)
46 return NULL;
47 }
48
49 inode = new_inode(sb);
50 if (!inode) {
51 relay_destroy_buf(buf);
52 return NULL;
53 }
54
55 inode->i_mode = mode;
56 inode->i_uid = 0;
57 inode->i_gid = 0;
58 inode->i_blksize = PAGE_CACHE_SIZE;
59 inode->i_blocks = 0;
60 inode->i_mapping->backing_dev_info = &relayfs_backing_dev_info;
61 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
62 switch (mode & S_IFMT) {
63 case S_IFREG:
64 inode->i_fop = &relayfs_file_operations;
65 RELAYFS_I(inode)->buf = buf;
66 break;
67 case S_IFDIR:
68 inode->i_op = &simple_dir_inode_operations;
69 inode->i_fop = &simple_dir_operations;
70
71 /* directory inodes start off with i_nlink == 2 (for "." entry) */
72 inode->i_nlink++;
73 break;
74 default:
75 break;
76 }
77
78 return inode;
79}
80
81/**
82 * relayfs_create_entry - create a relayfs directory or file
83 * @name: the name of the file to create
84 * @parent: parent directory
85 * @mode: mode
86 * @chan: relay channel associated with the file
87 *
88 * Returns the new dentry, NULL on failure
89 *
90 * Creates a file or directory with the specifed permissions.
91 */
92static struct dentry *relayfs_create_entry(const char *name,
93 struct dentry *parent,
94 int mode,
95 struct rchan *chan)
96{
97 struct dentry *d;
98 struct inode *inode;
99 int error = 0;
100
101 BUG_ON(!name || !(S_ISREG(mode) || S_ISDIR(mode)));
102
103 error = simple_pin_fs("relayfs", &relayfs_mount, &relayfs_mount_count);
104 if (error) {
105 printk(KERN_ERR "Couldn't mount relayfs: errcode %d\n", error);
106 return NULL;
107 }
108
109 if (!parent && relayfs_mount && relayfs_mount->mnt_sb)
110 parent = relayfs_mount->mnt_sb->s_root;
111
112 if (!parent) {
113 simple_release_fs(&relayfs_mount, &relayfs_mount_count);
114 return NULL;
115 }
116
117 parent = dget(parent);
118 down(&parent->d_inode->i_sem);
119 d = lookup_one_len(name, parent, strlen(name));
120 if (IS_ERR(d)) {
121 d = NULL;
122 goto release_mount;
123 }
124
125 if (d->d_inode) {
126 d = NULL;
127 goto release_mount;
128 }
129
130 inode = relayfs_get_inode(parent->d_inode->i_sb, mode, chan);
131 if (!inode) {
132 d = NULL;
133 goto release_mount;
134 }
135
136 d_instantiate(d, inode);
137 dget(d); /* Extra count - pin the dentry in core */
138
139 if (S_ISDIR(mode))
140 parent->d_inode->i_nlink++;
141
142 goto exit;
143
144release_mount:
145 simple_release_fs(&relayfs_mount, &relayfs_mount_count);
146
147exit:
148 up(&parent->d_inode->i_sem);
149 dput(parent);
150 return d;
151}
152
153/**
154 * relayfs_create_file - create a file in the relay filesystem
155 * @name: the name of the file to create
156 * @parent: parent directory
157 * @mode: mode, if not specied the default perms are used
158 * @chan: channel associated with the file
159 *
160 * Returns file dentry if successful, NULL otherwise.
161 *
162 * The file will be created user r on behalf of current user.
163 */
164struct dentry *relayfs_create_file(const char *name, struct dentry *parent,
165 int mode, struct rchan *chan)
166{
167 if (!mode)
168 mode = S_IRUSR;
169 mode = (mode & S_IALLUGO) | S_IFREG;
170
171 return relayfs_create_entry(name, parent, mode, chan);
172}
173
174/**
175 * relayfs_create_dir - create a directory in the relay filesystem
176 * @name: the name of the directory to create
177 * @parent: parent directory, NULL if parent should be fs root
178 *
179 * Returns directory dentry if successful, NULL otherwise.
180 *
181 * The directory will be created world rwx on behalf of current user.
182 */
183struct dentry *relayfs_create_dir(const char *name, struct dentry *parent)
184{
185 int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
186 return relayfs_create_entry(name, parent, mode, NULL);
187}
188
189/**
190 * relayfs_remove - remove a file or directory in the relay filesystem
191 * @dentry: file or directory dentry
192 *
193 * Returns 0 if successful, negative otherwise.
194 */
195int relayfs_remove(struct dentry *dentry)
196{
197 struct dentry *parent;
198 int error = 0;
199
200 if (!dentry)
201 return -EINVAL;
202 parent = dentry->d_parent;
203 if (!parent)
204 return -EINVAL;
205
206 parent = dget(parent);
207 down(&parent->d_inode->i_sem);
208 if (dentry->d_inode) {
209 if (S_ISDIR(dentry->d_inode->i_mode))
210 error = simple_rmdir(parent->d_inode, dentry);
211 else
212 error = simple_unlink(parent->d_inode, dentry);
213 if (!error)
214 d_delete(dentry);
215 }
216 if (!error)
217 dput(dentry);
218 up(&parent->d_inode->i_sem);
219 dput(parent);
220
221 if (!error)
222 simple_release_fs(&relayfs_mount, &relayfs_mount_count);
223
224 return error;
225}
226
227/**
228 * relayfs_remove_dir - remove a directory in the relay filesystem
229 * @dentry: directory dentry
230 *
231 * Returns 0 if successful, negative otherwise.
232 */
233int relayfs_remove_dir(struct dentry *dentry)
234{
235 return relayfs_remove(dentry);
236}
237
238/**
239 * relayfs_open - open file op for relayfs files
240 * @inode: the inode
241 * @filp: the file
242 *
243 * Increments the channel buffer refcount.
244 */
245static int relayfs_open(struct inode *inode, struct file *filp)
246{
247 struct rchan_buf *buf = RELAYFS_I(inode)->buf;
248 kref_get(&buf->kref);
249
250 return 0;
251}
252
253/**
254 * relayfs_mmap - mmap file op for relayfs files
255 * @filp: the file
256 * @vma: the vma describing what to map
257 *
258 * Calls upon relay_mmap_buf to map the file into user space.
259 */
260static int relayfs_mmap(struct file *filp, struct vm_area_struct *vma)
261{
262 struct inode *inode = filp->f_dentry->d_inode;
263 return relay_mmap_buf(RELAYFS_I(inode)->buf, vma);
264}
265
266/**
267 * relayfs_poll - poll file op for relayfs files
268 * @filp: the file
269 * @wait: poll table
270 *
271 * Poll implemention.
272 */
273static unsigned int relayfs_poll(struct file *filp, poll_table *wait)
274{
275 unsigned int mask = 0;
276 struct inode *inode = filp->f_dentry->d_inode;
277 struct rchan_buf *buf = RELAYFS_I(inode)->buf;
278
279 if (buf->finalized)
280 return POLLERR;
281
282 if (filp->f_mode & FMODE_READ) {
283 poll_wait(filp, &buf->read_wait, wait);
284 if (!relay_buf_empty(buf))
285 mask |= POLLIN | POLLRDNORM;
286 }
287
288 return mask;
289}
290
291/**
292 * relayfs_release - release file op for relayfs files
293 * @inode: the inode
294 * @filp: the file
295 *
296 * Decrements the channel refcount, as the filesystem is
297 * no longer using it.
298 */
299static int relayfs_release(struct inode *inode, struct file *filp)
300{
301 struct rchan_buf *buf = RELAYFS_I(inode)->buf;
302 kref_put(&buf->kref, relay_remove_buf);
303
304 return 0;
305}
306
307/**
308 * relayfs_read_consume - update the consumed count for the buffer
309 */
310static void relayfs_read_consume(struct rchan_buf *buf,
311 size_t read_pos,
312 size_t bytes_consumed)
313{
314 size_t subbuf_size = buf->chan->subbuf_size;
315 size_t n_subbufs = buf->chan->n_subbufs;
316 size_t read_subbuf;
317
318 if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
319 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
320 buf->bytes_consumed = 0;
321 }
322
323 buf->bytes_consumed += bytes_consumed;
324 read_subbuf = read_pos / buf->chan->subbuf_size;
325 if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
326 if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
327 (buf->offset == subbuf_size))
328 return;
329 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
330 buf->bytes_consumed = 0;
331 }
332}
333
334/**
335 * relayfs_read_avail - boolean, are there unconsumed bytes available?
336 */
337static int relayfs_read_avail(struct rchan_buf *buf, size_t read_pos)
338{
339 size_t bytes_produced, bytes_consumed, write_offset;
340 size_t subbuf_size = buf->chan->subbuf_size;
341 size_t n_subbufs = buf->chan->n_subbufs;
342 size_t produced = buf->subbufs_produced % n_subbufs;
343 size_t consumed = buf->subbufs_consumed % n_subbufs;
344
345 write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
346
347 if (consumed > produced) {
348 if ((produced > n_subbufs) &&
349 (produced + n_subbufs - consumed <= n_subbufs))
350 produced += n_subbufs;
351 } else if (consumed == produced) {
352 if (buf->offset > subbuf_size) {
353 produced += n_subbufs;
354 if (buf->subbufs_produced == buf->subbufs_consumed)
355 consumed += n_subbufs;
356 }
357 }
358
359 if (buf->offset > subbuf_size)
360 bytes_produced = (produced - 1) * subbuf_size + write_offset;
361 else
362 bytes_produced = produced * subbuf_size + write_offset;
363 bytes_consumed = consumed * subbuf_size + buf->bytes_consumed;
364
365 if (bytes_produced == bytes_consumed)
366 return 0;
367
368 relayfs_read_consume(buf, read_pos, 0);
369
370 return 1;
371}
372
373/**
374 * relayfs_read_subbuf_avail - return bytes available in sub-buffer
375 */
376static size_t relayfs_read_subbuf_avail(size_t read_pos,
377 struct rchan_buf *buf)
378{
379 size_t padding, avail = 0;
380 size_t read_subbuf, read_offset, write_subbuf, write_offset;
381 size_t subbuf_size = buf->chan->subbuf_size;
382
383 write_subbuf = (buf->data - buf->start) / subbuf_size;
384 write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
385 read_subbuf = read_pos / subbuf_size;
386 read_offset = read_pos % subbuf_size;
387 padding = buf->padding[read_subbuf];
388
389 if (read_subbuf == write_subbuf) {
390 if (read_offset + padding < write_offset)
391 avail = write_offset - (read_offset + padding);
392 } else
393 avail = (subbuf_size - padding) - read_offset;
394
395 return avail;
396}
397
398/**
399 * relayfs_read_start_pos - find the first available byte to read
400 *
401 * If the read_pos is in the middle of padding, return the
402 * position of the first actually available byte, otherwise
403 * return the original value.
404 */
405static size_t relayfs_read_start_pos(size_t read_pos,
406 struct rchan_buf *buf)
407{
408 size_t read_subbuf, padding, padding_start, padding_end;
409 size_t subbuf_size = buf->chan->subbuf_size;
410 size_t n_subbufs = buf->chan->n_subbufs;
411
412 read_subbuf = read_pos / subbuf_size;
413 padding = buf->padding[read_subbuf];
414 padding_start = (read_subbuf + 1) * subbuf_size - padding;
415 padding_end = (read_subbuf + 1) * subbuf_size;
416 if (read_pos >= padding_start && read_pos < padding_end) {
417 read_subbuf = (read_subbuf + 1) % n_subbufs;
418 read_pos = read_subbuf * subbuf_size;
419 }
420
421 return read_pos;
422}
423
424/**
425 * relayfs_read_end_pos - return the new read position
426 */
427static size_t relayfs_read_end_pos(struct rchan_buf *buf,
428 size_t read_pos,
429 size_t count)
430{
431 size_t read_subbuf, padding, end_pos;
432 size_t subbuf_size = buf->chan->subbuf_size;
433 size_t n_subbufs = buf->chan->n_subbufs;
434
435 read_subbuf = read_pos / subbuf_size;
436 padding = buf->padding[read_subbuf];
437 if (read_pos % subbuf_size + count + padding == subbuf_size)
438 end_pos = (read_subbuf + 1) * subbuf_size;
439 else
440 end_pos = read_pos + count;
441 if (end_pos >= subbuf_size * n_subbufs)
442 end_pos = 0;
443
444 return end_pos;
445}
446
447/**
448 * relayfs_read - read file op for relayfs files
449 * @filp: the file
450 * @buffer: the userspace buffer
451 * @count: number of bytes to read
452 * @ppos: position to read from
453 *
454 * Reads count bytes or the number of bytes available in the
455 * current sub-buffer being read, whichever is smaller.
456 */
457static ssize_t relayfs_read(struct file *filp,
458 char __user *buffer,
459 size_t count,
460 loff_t *ppos)
461{
462 struct inode *inode = filp->f_dentry->d_inode;
463 struct rchan_buf *buf = RELAYFS_I(inode)->buf;
464 size_t read_start, avail;
465 ssize_t ret = 0;
466 void *from;
467
468 down(&inode->i_sem);
469 if(!relayfs_read_avail(buf, *ppos))
470 goto out;
471
472 read_start = relayfs_read_start_pos(*ppos, buf);
473 avail = relayfs_read_subbuf_avail(read_start, buf);
474 if (!avail)
475 goto out;
476
477 from = buf->start + read_start;
478 ret = count = min(count, avail);
479 if (copy_to_user(buffer, from, count)) {
480 ret = -EFAULT;
481 goto out;
482 }
483 relayfs_read_consume(buf, read_start, count);
484 *ppos = relayfs_read_end_pos(buf, read_start, count);
485out:
486 up(&inode->i_sem);
487 return ret;
488}
489
490/**
491 * relayfs alloc_inode() implementation
492 */
493static struct inode *relayfs_alloc_inode(struct super_block *sb)
494{
495 struct relayfs_inode_info *p = kmem_cache_alloc(relayfs_inode_cachep, SLAB_KERNEL);
496 if (!p)
497 return NULL;
498 p->buf = NULL;
499
500 return &p->vfs_inode;
501}
502
503/**
504 * relayfs destroy_inode() implementation
505 */
506static void relayfs_destroy_inode(struct inode *inode)
507{
508 if (RELAYFS_I(inode)->buf)
509 relay_destroy_buf(RELAYFS_I(inode)->buf);
510
511 kmem_cache_free(relayfs_inode_cachep, RELAYFS_I(inode));
512}
513
514static void init_once(void *p, kmem_cache_t *cachep, unsigned long flags)
515{
516 struct relayfs_inode_info *i = p;
517 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR)
518 inode_init_once(&i->vfs_inode);
519}
520
521struct file_operations relayfs_file_operations = {
522 .open = relayfs_open,
523 .poll = relayfs_poll,
524 .mmap = relayfs_mmap,
525 .read = relayfs_read,
526 .llseek = no_llseek,
527 .release = relayfs_release,
528};
529
530static struct super_operations relayfs_ops = {
531 .statfs = simple_statfs,
532 .drop_inode = generic_delete_inode,
533 .alloc_inode = relayfs_alloc_inode,
534 .destroy_inode = relayfs_destroy_inode,
535};
536
537static int relayfs_fill_super(struct super_block * sb, void * data, int silent)
538{
539 struct inode *inode;
540 struct dentry *root;
541 int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
542
543 sb->s_blocksize = PAGE_CACHE_SIZE;
544 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
545 sb->s_magic = RELAYFS_MAGIC;
546 sb->s_op = &relayfs_ops;
547 inode = relayfs_get_inode(sb, mode, NULL);
548
549 if (!inode)
550 return -ENOMEM;
551
552 root = d_alloc_root(inode);
553 if (!root) {
554 iput(inode);
555 return -ENOMEM;
556 }
557 sb->s_root = root;
558
559 return 0;
560}
561
562static struct super_block * relayfs_get_sb(struct file_system_type *fs_type,
563 int flags, const char *dev_name,
564 void *data)
565{
566 return get_sb_single(fs_type, flags, data, relayfs_fill_super);
567}
568
569static struct file_system_type relayfs_fs_type = {
570 .owner = THIS_MODULE,
571 .name = "relayfs",
572 .get_sb = relayfs_get_sb,
573 .kill_sb = kill_litter_super,
574};
575
576static int __init init_relayfs_fs(void)
577{
578 int err;
579
580 relayfs_inode_cachep = kmem_cache_create("relayfs_inode_cache",
581 sizeof(struct relayfs_inode_info), 0,
582 0, init_once, NULL);
583 if (!relayfs_inode_cachep)
584 return -ENOMEM;
585
586 err = register_filesystem(&relayfs_fs_type);
587 if (err)
588 kmem_cache_destroy(relayfs_inode_cachep);
589
590 return err;
591}
592
593static void __exit exit_relayfs_fs(void)
594{
595 unregister_filesystem(&relayfs_fs_type);
596 kmem_cache_destroy(relayfs_inode_cachep);
597}
598
599module_init(init_relayfs_fs)
600module_exit(exit_relayfs_fs)
601
602EXPORT_SYMBOL_GPL(relayfs_file_operations);
603EXPORT_SYMBOL_GPL(relayfs_create_dir);
604EXPORT_SYMBOL_GPL(relayfs_remove_dir);
605
606MODULE_AUTHOR("Tom Zanussi <zanussi@us.ibm.com> and Karim Yaghmour <karim@opersys.com>");
607MODULE_DESCRIPTION("Relay Filesystem");
608MODULE_LICENSE("GPL");
609