Root/fs/coda/dir.c

1
2/*
3 * Directory operations for Coda filesystem
4 * Original version: (C) 1996 P. Braam and M. Callahan
5 * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
6 *
7 * Carnegie Mellon encourages users to contribute improvements to
8 * the Coda project. Contact Peter Braam (coda@cs.cmu.edu).
9 */
10
11#include <linux/types.h>
12#include <linux/kernel.h>
13#include <linux/time.h>
14#include <linux/fs.h>
15#include <linux/slab.h>
16#include <linux/file.h>
17#include <linux/stat.h>
18#include <linux/errno.h>
19#include <linux/string.h>
20#include <linux/spinlock.h>
21#include <linux/namei.h>
22
23#include <asm/uaccess.h>
24
25#include <linux/coda.h>
26#include <linux/coda_psdev.h>
27#include "coda_linux.h"
28#include "coda_cache.h"
29
30#include "coda_int.h"
31
32/* dir inode-ops */
33static int coda_create(struct inode *dir, struct dentry *new, int mode, struct nameidata *nd);
34static struct dentry *coda_lookup(struct inode *dir, struct dentry *target, struct nameidata *nd);
35static int coda_link(struct dentry *old_dentry, struct inode *dir_inode,
36             struct dentry *entry);
37static int coda_unlink(struct inode *dir_inode, struct dentry *entry);
38static int coda_symlink(struct inode *dir_inode, struct dentry *entry,
39            const char *symname);
40static int coda_mkdir(struct inode *dir_inode, struct dentry *entry, int mode);
41static int coda_rmdir(struct inode *dir_inode, struct dentry *entry);
42static int coda_rename(struct inode *old_inode, struct dentry *old_dentry,
43                       struct inode *new_inode, struct dentry *new_dentry);
44
45/* dir file-ops */
46static int coda_readdir(struct file *file, void *buf, filldir_t filldir);
47
48/* dentry ops */
49static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd);
50static int coda_dentry_delete(const struct dentry *);
51
52/* support routines */
53static int coda_venus_readdir(struct file *coda_file, void *buf,
54                  filldir_t filldir);
55
56/* same as fs/bad_inode.c */
57static int coda_return_EIO(void)
58{
59    return -EIO;
60}
61#define CODA_EIO_ERROR ((void *) (coda_return_EIO))
62
63const struct dentry_operations coda_dentry_operations =
64{
65    .d_revalidate = coda_dentry_revalidate,
66    .d_delete = coda_dentry_delete,
67};
68
69const struct inode_operations coda_dir_inode_operations =
70{
71    .create = coda_create,
72    .lookup = coda_lookup,
73    .link = coda_link,
74    .unlink = coda_unlink,
75    .symlink = coda_symlink,
76    .mkdir = coda_mkdir,
77    .rmdir = coda_rmdir,
78    .mknod = CODA_EIO_ERROR,
79    .rename = coda_rename,
80    .permission = coda_permission,
81    .getattr = coda_getattr,
82    .setattr = coda_setattr,
83};
84
85const struct file_operations coda_dir_operations = {
86    .llseek = generic_file_llseek,
87    .read = generic_read_dir,
88    .readdir = coda_readdir,
89    .open = coda_open,
90    .release = coda_release,
91    .fsync = coda_fsync,
92};
93
94
95/* inode operations for directories */
96/* access routines: lookup, readlink, permission */
97static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, struct nameidata *nd)
98{
99    struct inode *inode = NULL;
100    struct CodaFid resfid = { { 0, } };
101    int type = 0;
102    int error = 0;
103    const char *name = entry->d_name.name;
104    size_t length = entry->d_name.len;
105
106    if (length > CODA_MAXNAMLEN) {
107        printk(KERN_ERR "name too long: lookup, %s (%*s)\n",
108               coda_i2s(dir), (int)length, name);
109        return ERR_PTR(-ENAMETOOLONG);
110    }
111
112    /* control object, create inode on the fly */
113    if (coda_isroot(dir) && coda_iscontrol(name, length)) {
114        error = coda_cnode_makectl(&inode, dir->i_sb);
115        type = CODA_NOCACHE;
116        goto exit;
117    }
118
119    error = venus_lookup(dir->i_sb, coda_i2f(dir), name, length,
120                 &type, &resfid);
121    if (!error)
122        error = coda_cnode_make(&inode, &resfid, dir->i_sb);
123
124    if (error && error != -ENOENT)
125        return ERR_PTR(error);
126
127exit:
128    if (inode && (type & CODA_NOCACHE))
129        coda_flag_inode(inode, C_VATTR | C_PURGE);
130
131    return d_splice_alias(inode, entry);
132}
133
134
135int coda_permission(struct inode *inode, int mask, unsigned int flags)
136{
137    int error;
138
139    if (flags & IPERM_FLAG_RCU)
140        return -ECHILD;
141
142    mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
143 
144    if (!mask)
145        return 0;
146
147    if ((mask & MAY_EXEC) && !execute_ok(inode))
148        return -EACCES;
149
150    if (coda_cache_check(inode, mask))
151        return 0;
152
153    error = venus_access(inode->i_sb, coda_i2f(inode), mask);
154    
155    if (!error)
156        coda_cache_enter(inode, mask);
157
158    return error;
159}
160
161
162static inline void coda_dir_update_mtime(struct inode *dir)
163{
164#ifdef REQUERY_VENUS_FOR_MTIME
165    /* invalidate the directory cnode's attributes so we refetch the
166     * attributes from venus next time the inode is referenced */
167    coda_flag_inode(dir, C_VATTR);
168#else
169    /* optimistically we can also act as if our nose bleeds. The
170     * granularity of the mtime is coarse anyways so we might actually be
171     * right most of the time. Note: we only do this for directories. */
172    dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
173#endif
174}
175
176/* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
177 * trick to fool GNU find's optimizations. If we can't be sure of the link
178 * (because of volume mount points) we set i_nlink to 1 which forces find
179 * to consider every child as a possible directory. We should also never
180 * see an increment or decrement for deleted directories where i_nlink == 0 */
181static inline void coda_dir_inc_nlink(struct inode *dir)
182{
183    if (dir->i_nlink >= 2)
184        inc_nlink(dir);
185}
186
187static inline void coda_dir_drop_nlink(struct inode *dir)
188{
189    if (dir->i_nlink > 2)
190        drop_nlink(dir);
191}
192
193/* creation routines: create, mknod, mkdir, link, symlink */
194static int coda_create(struct inode *dir, struct dentry *de, int mode, struct nameidata *nd)
195{
196    int error;
197    const char *name=de->d_name.name;
198    int length=de->d_name.len;
199    struct inode *inode;
200    struct CodaFid newfid;
201    struct coda_vattr attrs;
202
203    if (coda_isroot(dir) && coda_iscontrol(name, length))
204        return -EPERM;
205
206    error = venus_create(dir->i_sb, coda_i2f(dir), name, length,
207                0, mode, &newfid, &attrs);
208    if (error)
209        goto err_out;
210
211    inode = coda_iget(dir->i_sb, &newfid, &attrs);
212    if (IS_ERR(inode)) {
213        error = PTR_ERR(inode);
214        goto err_out;
215    }
216
217    /* invalidate the directory cnode's attributes */
218    coda_dir_update_mtime(dir);
219    d_instantiate(de, inode);
220    return 0;
221err_out:
222    d_drop(de);
223    return error;
224}
225
226static int coda_mkdir(struct inode *dir, struct dentry *de, int mode)
227{
228    struct inode *inode;
229    struct coda_vattr attrs;
230    const char *name = de->d_name.name;
231    int len = de->d_name.len;
232    int error;
233    struct CodaFid newfid;
234
235    if (coda_isroot(dir) && coda_iscontrol(name, len))
236        return -EPERM;
237
238    attrs.va_mode = mode;
239    error = venus_mkdir(dir->i_sb, coda_i2f(dir),
240                   name, len, &newfid, &attrs);
241    if (error)
242        goto err_out;
243         
244    inode = coda_iget(dir->i_sb, &newfid, &attrs);
245    if (IS_ERR(inode)) {
246        error = PTR_ERR(inode);
247        goto err_out;
248    }
249
250    /* invalidate the directory cnode's attributes */
251    coda_dir_inc_nlink(dir);
252    coda_dir_update_mtime(dir);
253    d_instantiate(de, inode);
254    return 0;
255err_out:
256    d_drop(de);
257    return error;
258}
259
260/* try to make de an entry in dir_inodde linked to source_de */
261static int coda_link(struct dentry *source_de, struct inode *dir_inode,
262      struct dentry *de)
263{
264    struct inode *inode = source_de->d_inode;
265        const char * name = de->d_name.name;
266    int len = de->d_name.len;
267    int error;
268
269    if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
270        return -EPERM;
271
272    error = venus_link(dir_inode->i_sb, coda_i2f(inode),
273               coda_i2f(dir_inode), (const char *)name, len);
274    if (error) {
275        d_drop(de);
276        return error;
277    }
278
279    coda_dir_update_mtime(dir_inode);
280    ihold(inode);
281    d_instantiate(de, inode);
282    inc_nlink(inode);
283    return 0;
284}
285
286
287static int coda_symlink(struct inode *dir_inode, struct dentry *de,
288            const char *symname)
289{
290    const char *name = de->d_name.name;
291    int len = de->d_name.len;
292    int symlen;
293    int error;
294
295    if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
296        return -EPERM;
297
298    symlen = strlen(symname);
299    if (symlen > CODA_MAXPATHLEN)
300        return -ENAMETOOLONG;
301
302    /*
303     * This entry is now negative. Since we do not create
304     * an inode for the entry we have to drop it.
305     */
306    d_drop(de);
307    error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
308                  symname, symlen);
309
310    /* mtime is no good anymore */
311    if (!error)
312        coda_dir_update_mtime(dir_inode);
313
314    return error;
315}
316
317/* destruction routines: unlink, rmdir */
318static int coda_unlink(struct inode *dir, struct dentry *de)
319{
320        int error;
321    const char *name = de->d_name.name;
322    int len = de->d_name.len;
323
324    error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
325    if (error)
326        return error;
327
328    coda_dir_update_mtime(dir);
329    drop_nlink(de->d_inode);
330    return 0;
331}
332
333static int coda_rmdir(struct inode *dir, struct dentry *de)
334{
335    const char *name = de->d_name.name;
336    int len = de->d_name.len;
337    int error;
338
339    error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
340    if (!error) {
341        /* VFS may delete the child */
342        if (de->d_inode)
343            de->d_inode->i_nlink = 0;
344
345        /* fix the link count of the parent */
346        coda_dir_drop_nlink(dir);
347        coda_dir_update_mtime(dir);
348    }
349    return error;
350}
351
352/* rename */
353static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
354               struct inode *new_dir, struct dentry *new_dentry)
355{
356    const char *old_name = old_dentry->d_name.name;
357    const char *new_name = new_dentry->d_name.name;
358    int old_length = old_dentry->d_name.len;
359    int new_length = new_dentry->d_name.len;
360    int error;
361
362    error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
363                 coda_i2f(new_dir), old_length, new_length,
364                 (const char *) old_name, (const char *)new_name);
365    if (!error) {
366        if (new_dentry->d_inode) {
367            if (S_ISDIR(new_dentry->d_inode->i_mode)) {
368                coda_dir_drop_nlink(old_dir);
369                coda_dir_inc_nlink(new_dir);
370            }
371            coda_dir_update_mtime(old_dir);
372            coda_dir_update_mtime(new_dir);
373            coda_flag_inode(new_dentry->d_inode, C_VATTR);
374        } else {
375            coda_flag_inode(old_dir, C_VATTR);
376            coda_flag_inode(new_dir, C_VATTR);
377        }
378    }
379    return error;
380}
381
382
383/* file operations for directories */
384static int coda_readdir(struct file *coda_file, void *buf, filldir_t filldir)
385{
386    struct coda_file_info *cfi;
387    struct file *host_file;
388    int ret;
389
390    cfi = CODA_FTOC(coda_file);
391    BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
392    host_file = cfi->cfi_container;
393
394    if (!host_file->f_op)
395        return -ENOTDIR;
396
397    if (host_file->f_op->readdir)
398    {
399        /* potemkin case: we were handed a directory inode.
400         * We can't use vfs_readdir because we have to keep the file
401         * position in sync between the coda_file and the host_file.
402         * and as such we need grab the inode mutex. */
403        struct inode *host_inode = host_file->f_path.dentry->d_inode;
404
405        mutex_lock(&host_inode->i_mutex);
406        host_file->f_pos = coda_file->f_pos;
407
408        ret = -ENOENT;
409        if (!IS_DEADDIR(host_inode)) {
410            ret = host_file->f_op->readdir(host_file, buf, filldir);
411            file_accessed(host_file);
412        }
413
414        coda_file->f_pos = host_file->f_pos;
415        mutex_unlock(&host_inode->i_mutex);
416    }
417    else /* Venus: we must read Venus dirents from a file */
418        ret = coda_venus_readdir(coda_file, buf, filldir);
419
420    return ret;
421}
422
423static inline unsigned int CDT2DT(unsigned char cdt)
424{
425    unsigned int dt;
426
427    switch(cdt) {
428    case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
429    case CDT_FIFO: dt = DT_FIFO; break;
430    case CDT_CHR: dt = DT_CHR; break;
431    case CDT_DIR: dt = DT_DIR; break;
432    case CDT_BLK: dt = DT_BLK; break;
433    case CDT_REG: dt = DT_REG; break;
434    case CDT_LNK: dt = DT_LNK; break;
435    case CDT_SOCK: dt = DT_SOCK; break;
436    case CDT_WHT: dt = DT_WHT; break;
437    default: dt = DT_UNKNOWN; break;
438    }
439    return dt;
440}
441
442/* support routines */
443static int coda_venus_readdir(struct file *coda_file, void *buf,
444                  filldir_t filldir)
445{
446    int result = 0; /* # of entries returned */
447    struct coda_file_info *cfi;
448    struct coda_inode_info *cii;
449    struct file *host_file;
450    struct dentry *de;
451    struct venus_dirent *vdir;
452    unsigned long vdir_size =
453        (unsigned long)(&((struct venus_dirent *)0)->d_name);
454    unsigned int type;
455    struct qstr name;
456    ino_t ino;
457    int ret;
458
459    cfi = CODA_FTOC(coda_file);
460    BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
461    host_file = cfi->cfi_container;
462
463    de = coda_file->f_path.dentry;
464    cii = ITOC(de->d_inode);
465
466    vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
467    if (!vdir) return -ENOMEM;
468
469    if (coda_file->f_pos == 0) {
470        ret = filldir(buf, ".", 1, 0, de->d_inode->i_ino, DT_DIR);
471        if (ret < 0)
472            goto out;
473        result++;
474        coda_file->f_pos++;
475    }
476    if (coda_file->f_pos == 1) {
477        ret = filldir(buf, "..", 2, 1, de->d_parent->d_inode->i_ino, DT_DIR);
478        if (ret < 0)
479            goto out;
480        result++;
481        coda_file->f_pos++;
482    }
483    while (1) {
484        /* read entries from the directory file */
485        ret = kernel_read(host_file, coda_file->f_pos - 2, (char *)vdir,
486                  sizeof(*vdir));
487        if (ret < 0) {
488            printk(KERN_ERR "coda readdir: read dir %s failed %d\n",
489                   coda_f2s(&cii->c_fid), ret);
490            break;
491        }
492        if (ret == 0) break; /* end of directory file reached */
493
494        /* catch truncated reads */
495        if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
496            printk(KERN_ERR "coda readdir: short read on %s\n",
497                   coda_f2s(&cii->c_fid));
498            ret = -EBADF;
499            break;
500        }
501        /* validate whether the directory file actually makes sense */
502        if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
503            printk(KERN_ERR "coda readdir: invalid dir %s\n",
504                   coda_f2s(&cii->c_fid));
505            ret = -EBADF;
506            break;
507        }
508
509        name.len = vdir->d_namlen;
510        name.name = vdir->d_name;
511
512        /* Make sure we skip '.' and '..', we already got those */
513        if (name.name[0] == '.' && (name.len == 1 ||
514            (vdir->d_name[1] == '.' && name.len == 2)))
515            vdir->d_fileno = name.len = 0;
516
517        /* skip null entries */
518        if (vdir->d_fileno && name.len) {
519            /* try to look up this entry in the dcache, that way
520             * userspace doesn't have to worry about breaking
521             * getcwd by having mismatched inode numbers for
522             * internal volume mountpoints. */
523            ino = find_inode_number(de, &name);
524            if (!ino) ino = vdir->d_fileno;
525
526            type = CDT2DT(vdir->d_type);
527            ret = filldir(buf, name.name, name.len,
528                      coda_file->f_pos, ino, type);
529            /* failure means no space for filling in this round */
530            if (ret < 0) break;
531            result++;
532        }
533        /* we'll always have progress because d_reclen is unsigned and
534         * we've already established it is non-zero. */
535        coda_file->f_pos += vdir->d_reclen;
536    }
537out:
538    kfree(vdir);
539    return result ? result : ret;
540}
541
542/* called when a cache lookup succeeds */
543static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd)
544{
545    struct inode *inode;
546    struct coda_inode_info *cii;
547
548    if (nd->flags & LOOKUP_RCU)
549        return -ECHILD;
550
551    inode = de->d_inode;
552    if (!inode || coda_isroot(inode))
553        goto out;
554    if (is_bad_inode(inode))
555        goto bad;
556
557    cii = ITOC(de->d_inode);
558    if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
559        goto out;
560
561    shrink_dcache_parent(de);
562
563    /* propagate for a flush */
564    if (cii->c_flags & C_FLUSH)
565        coda_flag_inode_children(inode, C_FLUSH);
566
567    if (de->d_count > 1)
568        /* pretend it's valid, but don't change the flags */
569        goto out;
570
571    /* clear the flags. */
572    spin_lock(&cii->c_lock);
573    cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
574    spin_unlock(&cii->c_lock);
575bad:
576    return 0;
577out:
578    return 1;
579}
580
581/*
582 * This is the callback from dput() when d_count is going to 0.
583 * We use this to unhash dentries with bad inodes.
584 */
585static int coda_dentry_delete(const struct dentry * dentry)
586{
587    int flags;
588
589    if (!dentry->d_inode)
590        return 0;
591
592    flags = (ITOC(dentry->d_inode)->c_flags) & C_PURGE;
593    if (is_bad_inode(dentry->d_inode) || flags) {
594        return 1;
595    }
596    return 0;
597}
598
599
600
601/*
602 * This is called when we want to check if the inode has
603 * changed on the server. Coda makes this easy since the
604 * cache manager Venus issues a downcall to the kernel when this
605 * happens
606 */
607int coda_revalidate_inode(struct dentry *dentry)
608{
609    struct coda_vattr attr;
610    int error;
611    int old_mode;
612    ino_t old_ino;
613    struct inode *inode = dentry->d_inode;
614    struct coda_inode_info *cii = ITOC(inode);
615
616    if (!cii->c_flags)
617        return 0;
618
619    if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
620        error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
621        if (error)
622            return -EIO;
623
624        /* this inode may be lost if:
625           - it's ino changed
626           - type changes must be permitted for repair and
627           missing mount points.
628        */
629        old_mode = inode->i_mode;
630        old_ino = inode->i_ino;
631        coda_vattr_to_iattr(inode, &attr);
632
633        if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
634            printk("Coda: inode %ld, fid %s changed type!\n",
635                   inode->i_ino, coda_f2s(&(cii->c_fid)));
636        }
637
638        /* the following can happen when a local fid is replaced
639           with a global one, here we lose and declare the inode bad */
640        if (inode->i_ino != old_ino)
641            return -EIO;
642        
643        coda_flag_inode_children(inode, C_FLUSH);
644
645        spin_lock(&cii->c_lock);
646        cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
647        spin_unlock(&cii->c_lock);
648    }
649    return 0;
650}
651

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