dir.c 15.9 KB
Newer Older
David Howells's avatar
David Howells committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
/* dir.c: AFS filesystem directory handling
 *
 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include "vnode.h"
#include "volume.h"
#include <rxrpc/call.h>
#include "super.h"
#include "internal.h"

static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry);
static int afs_dir_open(struct inode *inode, struct file *file);
static int afs_dir_readdir(struct file *file, void *dirent, filldir_t filldir);
static int afs_d_revalidate(struct dentry *dentry, int flags);
static int afs_d_delete(struct dentry *dentry);
static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen, loff_t fpos,
				     ino_t ino, unsigned dtype);

struct file_operations afs_dir_file_operations = {
	.open		= afs_dir_open,
	.readdir	= afs_dir_readdir,
};

struct inode_operations afs_dir_inode_operations = {
	.lookup		= afs_dir_lookup,
	.getattr	= afs_inode_getattr,
David Howells's avatar
David Howells committed
42 43 44 45 46 47 48 49 50
#if 0 /* TODO */
	.create		= afs_dir_create,
	.link		= afs_dir_link,
	.unlink		= afs_dir_unlink,
	.symlink	= afs_dir_symlink,
	.mkdir		= afs_dir_mkdir,
	.rmdir		= afs_dir_rmdir,
	.mknod		= afs_dir_mknod,
	.rename		= afs_dir_rename,
David Howells's avatar
David Howells committed
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
#endif
};

static struct dentry_operations afs_fs_dentry_operations = {
	.d_revalidate	= afs_d_revalidate,
	.d_delete	= afs_d_delete,
};

#define AFS_DIR_HASHTBL_SIZE	128
#define AFS_DIR_DIRENT_SIZE	32
#define AFS_DIRENT_PER_BLOCK	64

typedef union afs_dirent {
	struct {
		u8	valid;
		u8	unused[1];
		u16	hash_next;
		u32	vnode;
		u32	unique;
		u8	name[16];
		u8	overflow[4];	/* if any char of the name (inc NUL) reaches here, consume
					 * the next dirent too */
73
	} parts;
David Howells's avatar
David Howells committed
74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250
	u8	extended_name[32];
} afs_dirent_t;

/* AFS directory page header (one at the beginning of every 2048-byte chunk) */
typedef struct afs_dir_pagehdr {
	u16	npages;
	u16	magic;
#define AFS_DIR_MAGIC htons(1234)
	u8	nentries;
	u8	bitmap[8];
	u8	pad[19];
} afs_dir_pagehdr_t;

/* directory block layout */
typedef union afs_dir_block {

	afs_dir_pagehdr_t pagehdr;

	struct {
		afs_dir_pagehdr_t pagehdr;
		u8		alloc_ctrs[128];
		u16		hashtable[AFS_DIR_HASHTBL_SIZE]; /* dir hash table */
	} hdr;

	afs_dirent_t dirents[AFS_DIRENT_PER_BLOCK];
} afs_dir_block_t;

/* layout on a linux VM page */
typedef struct afs_dir_page {
	afs_dir_block_t	blocks[PAGE_SIZE/sizeof(afs_dir_block_t)];
} afs_dir_page_t;

struct afs_dir_lookup_cookie {
	afs_fid_t	fid;
	const char	*name;
	size_t		nlen;
	int		found;
};

/*****************************************************************************/
/*
 * check that a directory page is valid
 */
static inline void afs_dir_check_page(struct inode *dir, struct page *page)
{
	afs_dir_page_t *dbuf;
	loff_t latter;
	int tmp, qty;

#if 0
	/* check the page count */
	qty = desc.size/sizeof(dbuf->blocks[0]);
	if (qty==0)
		goto error;

	if (page->index==0 && qty!=ntohs(dbuf->blocks[0].pagehdr.npages)) {
		printk("kAFS: %s(%lu): wrong number of dir blocks %d!=%hu\n",
		       __FUNCTION__,dir->i_ino,qty,ntohs(dbuf->blocks[0].pagehdr.npages));
		goto error;
	}
#endif

	/* determine how many magic numbers there should be in this page */
	latter = dir->i_size - (page->index << PAGE_CACHE_SHIFT);
	if (latter >= PAGE_SIZE)
		qty = PAGE_SIZE;
	else
		qty = latter;
	qty /= sizeof(afs_dir_block_t);

	/* check them */
	dbuf = page_address(page);
	for (tmp=0; tmp<qty; tmp++) {
		if (dbuf->blocks[tmp].pagehdr.magic != AFS_DIR_MAGIC) {
			printk("kAFS: %s(%lu): bad magic %d/%d is %04hx\n",
			       __FUNCTION__,dir->i_ino,tmp,
			       qty,ntohs(dbuf->blocks[tmp].pagehdr.magic));
			goto error;
		}
	}

	SetPageChecked(page);
	return;

 error:
	SetPageChecked(page);
	SetPageError(page);

} /* end afs_dir_check_page() */

/*****************************************************************************/
/*
 * discard a page cached in the pagecache
 */
static inline void afs_dir_put_page(struct page *page)
{
	kunmap(page);
	page_cache_release(page);

} /* end afs_dir_put_page() */

/*****************************************************************************/
/*
 * get a page into the pagecache
 */
static struct page *afs_dir_get_page(struct inode *dir, unsigned long index)
{
	struct page *page;

	_enter("{%lu},%lu",dir->i_ino,index);

	page = read_cache_page(dir->i_mapping,index,
			       (filler_t*)dir->i_mapping->a_ops->readpage,NULL);
	if (!IS_ERR(page)) {
		wait_on_page_locked(page);
		kmap(page);
		if (!PageUptodate(page))
			goto fail;
		if (!PageChecked(page))
			afs_dir_check_page(dir,page);
		if (PageError(page))
			goto fail;
	}
	return page;

 fail:
	afs_dir_put_page(page);
	return ERR_PTR(-EIO);
} /* end afs_dir_get_page() */

/*****************************************************************************/
/*
 * open an AFS directory file
 */
static int afs_dir_open(struct inode *inode, struct file *file)
{
	_enter("{%lu}",inode->i_ino);

	if (sizeof(afs_dir_block_t) != 2048) BUG();
	if (sizeof(afs_dirent_t) != 32) BUG();

	if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED)
		return -ENOENT;

	_leave(" = 0");
	return 0;

} /* end afs_dir_open() */

/*****************************************************************************/
/*
 * deal with one block in an AFS directory
 */
static int afs_dir_iterate_block(unsigned *fpos,
				    afs_dir_block_t *block,
				    unsigned blkoff,
				    void *cookie,
				    filldir_t filldir)
{
	afs_dirent_t *dire;
	unsigned offset, next, curr;
	size_t nlen;
	int tmp, ret;

	_enter("%u,%x,%p,,",*fpos,blkoff,block);

	curr = (*fpos - blkoff) / sizeof(afs_dirent_t);

	/* walk through the block, an entry at a time */
	for (offset = AFS_DIRENT_PER_BLOCK - block->pagehdr.nentries;
	     offset < AFS_DIRENT_PER_BLOCK;
	     offset = next
	     ) {
		next = offset + 1;

		/* skip entries marked unused in the bitmap */
		if (!(block->pagehdr.bitmap[offset/8] & (1 << (offset % 8)))) {
David Howells's avatar
David Howells committed
251
			_debug("ENT[%Zu.%u]: unused\n",blkoff/sizeof(afs_dir_block_t),offset);
David Howells's avatar
David Howells committed
252 253 254 255 256 257 258
			if (offset>=curr)
				*fpos = blkoff + next * sizeof(afs_dirent_t);
			continue;
		}

		/* got a valid entry */
		dire = &block->dirents[offset];
259
		nlen = strnlen(dire->parts.name,sizeof(*block) - offset*sizeof(afs_dirent_t));
David Howells's avatar
David Howells committed
260

David Howells's avatar
David Howells committed
261
		_debug("ENT[%Zu.%u]: %s %Zu \"%s\"\n",
David Howells's avatar
David Howells committed
262
		       blkoff/sizeof(afs_dir_block_t),offset,
David Howells's avatar
David Howells committed
263 264
		       (offset<curr ? "skip" : "fill"),
		       nlen,dire->u.name);
David Howells's avatar
David Howells committed
265 266 267 268

		/* work out where the next possible entry is */
		for (tmp=nlen; tmp>15; tmp-=sizeof(afs_dirent_t)) {
			if (next>=AFS_DIRENT_PER_BLOCK) {
David Howells's avatar
David Howells committed
269 270
				_debug("ENT[%Zu.%u]:"
				       " %u travelled beyond end dir block (len %u/%Zu)\n",
David Howells's avatar
David Howells committed
271 272 273 274
				       blkoff/sizeof(afs_dir_block_t),offset,next,tmp,nlen);
				return -EIO;
			}
			if (!(block->pagehdr.bitmap[next/8] & (1 << (next % 8)))) {
David Howells's avatar
David Howells committed
275
				_debug("ENT[%Zu.%u]: %u unmarked extension (len %u/%Zu)\n",
David Howells's avatar
David Howells committed
276 277 278 279
				       blkoff/sizeof(afs_dir_block_t),offset,next,tmp,nlen);
				return -EIO;
			}

David Howells's avatar
David Howells committed
280
			_debug("ENT[%Zu.%u]: ext %u/%Zu\n",
David Howells's avatar
David Howells committed
281 282 283 284 285 286 287 288 289 290
			       blkoff/sizeof(afs_dir_block_t),next,tmp,nlen);
			next++;
		}

		/* skip if starts before the current position */
		if (offset<curr)
			continue;

		/* found the next entry */
		ret = filldir(cookie,
291
			      dire->parts.name,
David Howells's avatar
David Howells committed
292 293
			      nlen,
			      blkoff + offset * sizeof(afs_dirent_t),
294 295
			      ntohl(dire->parts.vnode),
			      filldir==afs_dir_lookup_filldir ? dire->parts.unique : DT_UNKNOWN);
David Howells's avatar
David Howells committed
296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397
		if (ret<0) {
			_leave(" = 0 [full]");
			return 0;
		}

		*fpos = blkoff + next * sizeof(afs_dirent_t);
	}

	_leave(" = 1 [more]");
	return 1;
} /* end afs_dir_iterate_block() */

/*****************************************************************************/
/*
 * read an AFS directory
 */
static int afs_dir_iterate(struct inode *dir, unsigned *fpos, void *cookie, filldir_t filldir)
{
	afs_dir_block_t	*dblock;
	afs_dir_page_t *dbuf;
	struct page *page;
	unsigned blkoff, limit;
	int ret;

	_enter("{%lu},%u,,",dir->i_ino,*fpos);

	if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
		_leave(" = -ESTALE");
		return -ESTALE;
	}

	/* round the file position up to the next entry boundary */
	*fpos += sizeof(afs_dirent_t) - 1;
	*fpos &= ~(sizeof(afs_dirent_t) - 1);

	/* walk through the blocks in sequence */
	ret = 0;
	while (*fpos < dir->i_size) {
		blkoff = *fpos & ~(sizeof(afs_dir_block_t) - 1);

		/* fetch the appropriate page from the directory */
		page = afs_dir_get_page(dir,blkoff/PAGE_SIZE);
		if (IS_ERR(page)) {
			ret = PTR_ERR(page);
			break;
		}

		limit = blkoff & ~(PAGE_SIZE-1);

		dbuf = page_address(page);

		/* deal with the individual blocks stashed on this page */
		do {
			dblock = &dbuf->blocks[(blkoff % PAGE_SIZE) / sizeof(afs_dir_block_t)];
			ret = afs_dir_iterate_block(fpos,dblock,blkoff,cookie,filldir);
			if (ret!=1) {
				afs_dir_put_page(page);
				goto out;
			}

			blkoff += sizeof(afs_dir_block_t);

		} while (*fpos < dir->i_size && blkoff < limit);

		afs_dir_put_page(page);
		ret = 0;
	}

 out:
	_leave(" = %d",ret);
	return ret;
} /* end afs_dir_iterate() */

/*****************************************************************************/
/*
 * read an AFS directory
 */
static int afs_dir_readdir(struct file *file, void *cookie, filldir_t filldir)
{
	unsigned fpos;
	int ret;

	_enter("{%Ld,{%lu}}",file->f_pos,file->f_dentry->d_inode->i_ino);

	fpos = file->f_pos;
	ret = afs_dir_iterate(file->f_dentry->d_inode,&fpos,cookie,filldir);
	file->f_pos = fpos;

	_leave(" = %d",ret);
	return ret;
} /* end afs_dir_readdir() */

/*****************************************************************************/
/*
 * search the directory for a name
 * - if afs_dir_iterate_block() spots this function, it'll pass the FID uniquifier through dtype
 */
static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen, loff_t fpos,
				  ino_t ino, unsigned dtype)
{
	struct afs_dir_lookup_cookie *cookie = _cookie;

David Howells's avatar
David Howells committed
398
	_enter("{%s,%Zu},%s,%u,,%lu,%u",cookie->name,cookie->nlen,name,nlen,ino,ntohl(dtype));
David Howells's avatar
David Howells committed
399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471

	if (cookie->nlen != nlen || memcmp(cookie->name,name,nlen)!=0) {
		_leave(" = 0 [no]");
		return 0;
	}

	cookie->fid.vnode = ino;
	cookie->fid.unique = ntohl(dtype);
	cookie->found = 1;

	_leave(" = -1 [found]");
	return -1;
} /* end afs_dir_lookup_filldir() */

/*****************************************************************************/
/*
 * look up an entry in a directory
 */
static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry)
{
	struct afs_dir_lookup_cookie cookie;
	struct afs_super_info *as;
	struct inode *inode;
	afs_vnode_t *vnode;
	unsigned fpos;
	int ret;

	_enter("{%lu},{%s}",dir->i_ino,dentry->d_name.name);

	/* insanity checks first */
	if (sizeof(afs_dir_block_t) != 2048) BUG();
	if (sizeof(afs_dirent_t) != 32) BUG();

	if (dentry->d_name.len > 255) {
		_leave(" = -ENAMETOOLONG");
		return ERR_PTR(-ENAMETOOLONG);
	}

	vnode = AFS_FS_I(dir);
	if (vnode->flags & AFS_VNODE_DELETED) {
		_leave(" = -ESTALE");
		return ERR_PTR(-ESTALE);
	}

	as = dir->i_sb->s_fs_info;

	/* search the directory */
	cookie.name	= dentry->d_name.name;
	cookie.nlen	= dentry->d_name.len;
	cookie.fid.vid	= as->volume->vid;
	cookie.found	= 0;

	fpos = 0;
	ret = afs_dir_iterate(dir,&fpos,&cookie,afs_dir_lookup_filldir);
	if (ret<0) {
		_leave(" = %d",ret);
		return ERR_PTR(ret);
	}

	ret = -ENOENT;
	if (!cookie.found) {
		_leave(" = %d",ret);
		return ERR_PTR(ret);
	}

	/* instantiate the dentry */
	ret = afs_iget(dir->i_sb,&cookie.fid,&inode);
	if (ret<0) {
		_leave(" = %d",ret);
		return ERR_PTR(ret);
	}

	dentry->d_op = &afs_fs_dentry_operations;
David Howells's avatar
David Howells committed
472
	dentry->d_fsdata = (void*) (unsigned long) vnode->status.version;
David Howells's avatar
David Howells committed
473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499

	d_add(dentry,inode);
	_leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%lu }",
	       cookie.fid.vnode,
	       cookie.fid.unique,
	       dentry->d_inode->i_ino,
	       dentry->d_inode->i_version);

	return NULL;
} /* end afs_dir_lookup() */

/*****************************************************************************/
/*
 * check that a dentry lookup hit has found a valid entry
 * - NOTE! the hit can be a negative hit too, so we can't assume we have an inode
 * (derived from nfs_lookup_revalidate)
 */
static int afs_d_revalidate(struct dentry *dentry, int flags)
{
	struct afs_dir_lookup_cookie cookie;
	struct dentry *parent;
	struct inode *inode, *dir;
	unsigned fpos;
	int ret;

	_enter("%s,%x",dentry->d_name.name,flags);

Andrew Morton's avatar
Andrew Morton committed
500
	parent = dget_parent(dentry);
David Howells's avatar
David Howells committed
501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531
	dir = parent->d_inode;
	inode = dentry->d_inode;

	/* handle a negative inode */
	if (!inode)
		goto out_bad;

	/* handle a bad inode */
	if (is_bad_inode(inode)) {
		printk("kAFS: afs_d_revalidate: %s/%s has bad inode\n",
		       dentry->d_parent->d_name.name,dentry->d_name.name);
		goto out_bad;
	}

	/* force a full look up if the parent directory changed since last the server was consulted
	 * - otherwise this inode must still exist, even if the inode details themselves have
	 *   changed
	 */
	if (AFS_FS_I(dir)->flags & AFS_VNODE_CHANGED)
		afs_vnode_fetch_status(AFS_FS_I(dir));

	if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
		_debug("%s: parent dir deleted",dentry->d_name.name);
		goto out_bad;
	}

	if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED) {
		_debug("%s: file already deleted",dentry->d_name.name);
		goto out_bad;
	}

David Howells's avatar
David Howells committed
532 533
	if ((unsigned long)dentry->d_fsdata != (unsigned long)AFS_FS_I(dir)->status.version) {
		_debug("%s: parent changed %lu -> %u",
David Howells's avatar
David Howells committed
534
		       dentry->d_name.name,
David Howells's avatar
David Howells committed
535
		       (unsigned long)dentry->d_fsdata,
David Howells's avatar
David Howells committed
536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575
		       (unsigned)AFS_FS_I(dir)->status.version);

		/* search the directory for this vnode */
		cookie.name	= dentry->d_name.name;
		cookie.nlen	= dentry->d_name.len;
		cookie.fid.vid	= AFS_FS_I(inode)->volume->vid;
		cookie.found	= 0;

		fpos = 0;
		ret = afs_dir_iterate(dir,&fpos,&cookie,afs_dir_lookup_filldir);
		if (ret<0) {
			_debug("failed to iterate dir %s: %d",parent->d_name.name,ret);
			goto out_bad;
		}

		if (!cookie.found) {
			_debug("%s: dirent not found",dentry->d_name.name);
			goto not_found;
		}

		/* if the vnode ID has changed, then the dirent points to a different file */
		if (cookie.fid.vnode!=AFS_FS_I(inode)->fid.vnode) {
			_debug("%s: dirent changed",dentry->d_name.name);
			goto not_found;
		}

		/* if the vnode ID uniqifier has changed, then the file has been deleted */
		if (cookie.fid.unique!=AFS_FS_I(inode)->fid.unique) {
			_debug("%s: file deleted (uq %u -> %u I:%lu)",
			       dentry->d_name.name,
			       cookie.fid.unique,
			       AFS_FS_I(inode)->fid.unique,
			       inode->i_version);
			spin_lock(&AFS_FS_I(inode)->lock);
			AFS_FS_I(inode)->flags |= AFS_VNODE_DELETED;
			spin_unlock(&AFS_FS_I(inode)->lock);
			invalidate_inode_pages(inode->i_mapping);
			goto out_bad;
		}

David Howells's avatar
David Howells committed
576
		dentry->d_fsdata = (void*) (unsigned long) AFS_FS_I(dir)->status.version;
David Howells's avatar
David Howells committed
577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630
	}

 out_valid:
	dput(parent);
	_leave(" = 1 [valid]");
	return 1;

	/* the dirent, if it exists, now points to a different vnode */
 not_found:
	dentry->d_flags |= DCACHE_NFSFS_RENAMED;

 out_bad:
	if (inode) {
		/* don't unhash if we have submounts */
		if (have_submounts(dentry))
			goto out_valid;
	}

	shrink_dcache_parent(dentry);

	_debug("dropping dentry %s/%s",dentry->d_parent->d_name.name,dentry->d_name.name);
	d_drop(dentry);

	dput(parent);

	_leave(" = 0 [bad]");
	return 0;
} /* end afs_d_revalidate() */

/*****************************************************************************/
/*
 * allow the VFS to enquire as to whether a dentry should be unhashed (mustn't sleep)
 * - called from dput() when d_count is going to 0.
 * - return 1 to request dentry be unhashed, 0 otherwise
 */
static int afs_d_delete(struct dentry *dentry)
{
	_enter("%s",dentry->d_name.name);

	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
		goto zap;

	if (dentry->d_inode) {
		if (AFS_FS_I(dentry->d_inode)->flags & AFS_VNODE_DELETED)
			goto zap;
	}

	_leave(" = 0 [keep]");
	return 0;

 zap:
	_leave(" = 1 [zap]");
	return 1;
} /* end afs_d_delete() */