linux.fs.ext2.namei.c
/*
* linux/fs/ext2/namei.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card ([e-mail])
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* from
*
* linux/fs/minix/namei.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/

#include <asm/segment.h>

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/locks.h>

/*
* comment out this line if you want names > EXT2_NAME_LEN chars to be
* truncated. Else they will be disallowed.
*/
/* #define NO_TRUNCATE */

/*
* define how far ahead to read directories while searching them.
*/
#define NAMEI_RA_CHUNKS 2
#define NAMEI_RA_BLOCKS 4
#define NAMEI_RA_SIZE (NAMEI_RA_CHUNKS * NAMEI_RA_BLOCKS)
#define NAMEI_RA_INDEX(c,b) (((c) * NAMEI_RA_BLOCKS) + (b))

/*
* NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
*/
static int ext2_match (int len, const char * const name,
struct ext2_dir_entry * de)
{
if (!de || !de->inode || len > EXT2_NAME_LEN)
return 0;
/*
* "" means "." ---> so paths like "/usr/lib//libc.a" work
*/
if (!len && de->name_len == 1 && (de->name[0] == '.') &&
(de->name[1] == '\0'))
return 1;
if (len != de->name_len)
return 0;
return !memcmp(name, de->name, len);
}

/*
* ext2_find_entry()
*
* finds an entry in the specified directory with the wanted name. It
* returns the cache buffer in which the entry was found, and the entry
* itself (as a parameter - res_dir). It does NOT read the inode of the
* entry - you'll have to do that yourself if you want to.
*/
static struct buffer_head * ext2_find_entry (struct inode * dir,
const char * const name, int namelen,
struct ext2_dir_entry ** res_dir)
{
struct super_block * sb;
struct buffer_head * bh_use[NAMEI_RA_SIZE];
struct buffer_head * bh_read[NAMEI_RA_SIZE];
unsigned long offset;
int block, toread, i, err;

*res_dir = NULL;
if (!dir)
return NULL;
sb = dir->i_sb;

#ifdef NO_TRUNCATE
if (namelen > EXT2_NAME_LEN)
return NULL;
#else
if (namelen > EXT2_NAME_LEN)
namelen = EXT2_NAME_LEN;
#endif

memset (bh_use, 0, sizeof (bh_use));
toread = 0;
for (block = 0; block < NAMEI_RA_SIZE; ++block) {
struct buffer_head * bh;

if ((block << EXT2_BLOCK_SIZE_BITS (sb)) >= dir->i_size)
break;
bh = ext2_getblk (dir, block, 0, &err);
bh_use[block] = bh;
if (bh && !buffer_uptodate(bh))
bh_read[toread++] = bh;
}

for (block = 0, offset = 0; offset < dir->i_size; block++) {
struct buffer_head * bh;
struct ext2_dir_entry * de;
char * dlimit;

if ((block % NAMEI_RA_BLOCKS) == 0 && toread) {
ll_rw_block (READ, toread, bh_read);
toread = 0;
}
bh = bh_use[block % NAMEI_RA_SIZE];
if (!bh) {
ext2_error (sb, "ext2_find_entry",
"directory #%lu contains a hole at offset %lu",
dir->i_ino, offset);
offset += sb->s_blocksize;
continue;
}
wait_on_buffer (bh);
if (!buffer_uptodate(bh)) {
/*
* read error: all bets are off
*/
break;
}

de = (struct ext2_dir_entry *) bh->b_data;
dlimit = bh->b_data + sb->s_blocksize;
while ((char *) de < dlimit) {
if (!ext2_check_dir_entry ("ext2_find_entry", dir,
de, bh, offset))
goto failure;
if (de->inode != 0 && ext2_match (namelen, name, de)) {
for (i = 0; i < NAMEI_RA_SIZE; ++i) {
if (bh_use[i] != bh)
brelse (bh_use[i]);
}
*res_dir = de;
return bh;
}
offset += de->rec_len;
de = (struct ext2_dir_entry *)
((char *) de + de->rec_len);
}

brelse (bh);
if (((block + NAMEI_RA_SIZE) << EXT2_BLOCK_SIZE_BITS (sb)) >=
dir->i_size)
bh = NULL;
else
bh = ext2_getblk (dir, block + NAMEI_RA_SIZE, 0, &err);
bh_use[block % NAMEI_RA_SIZE] = bh;
if (bh && !buffer_uptodate(bh))
bh_read[toread++] = bh;
}

failure:
for (i = 0; i < NAMEI_RA_SIZE; ++i)
brelse (bh_use[i]);
return NULL;
}

int ext2_lookup (struct inode * dir, const char * name, int len,
struct inode ** result)
{
unsigned long ino;
struct ext2_dir_entry * de;
struct buffer_head * bh;

*result = NULL;
if (!dir)
return -ENOENT;
if (!S_ISDIR(dir->i_mode)) {
iput (dir);
return -ENOENT;
}
if (dcache_lookup(dir, name, len, &ino)) {
if (!ino) {
iput(dir);
return -ENOENT;
}
if (!(*result = iget (dir->i_sb, ino))) {
iput (dir);
return -EACCES;
}
iput (dir);
return 0;
}
ino = dir->i_version;
if (!(bh = ext2_find_entry (dir, name, len, &de))) {
if (ino == dir->i_version)
dcache_add(dir, name, len, 0);
iput (dir);
return -ENOENT;
}
ino = de->inode;
dcache_add(dir, name, len, ino);
brelse (bh);
if (!(*result = iget (dir->i_sb, ino))) {
iput (dir);
return -EACCES;
}
iput (dir);
return 0;
}

/*
* ext2_add_entry()
*
* adds a file entry to the specified directory, using the same
* semantics as ext2_find_entry(). It returns NULL if it failed.
*
* NOTE!! The inode part of 'de' is left at 0 - which means you
* may not sleep between calling this and putting something into
* the entry, as someone else might have used it while you slept.
*/
static struct buffer_head * ext2_add_entry (struct inode * dir,
const char * name, int namelen,
struct ext2_dir_entry ** res_dir,
int *err)
{
unsigned long offset;
unsigned short rec_len;
struct buffer_head * bh;
struct ext2_dir_entry * de, * de1;
struct super_block * sb;

*err = -EINVAL;
*res_dir = NULL;
if (!dir)
return NULL;
sb = dir->i_sb;
#ifdef NO_TRUNCATE
if (namelen > EXT2_NAME_LEN)
return NULL;
#else
if (namelen > EXT2_NAME_LEN)
namelen = EXT2_NAME_LEN;
#endif
if (!namelen)
return NULL;
/*
* Is this a busy deleted directory? Can't create new files if so
*/
if (dir->i_size == 0)
{
*err = -ENOENT;
return NULL;
}
bh = ext2_bread (dir, 0, 0, err);
if (!bh)
return NULL;
rec_len = EXT2_DIR_REC_LEN(namelen);
offset = 0;
de = (struct ext2_dir_entry *) bh->b_data;
*err = -ENOSPC;
while (1) {
if ((char *)de >= sb->s_blocksize + bh->b_data) {
brelse (bh);
bh = NULL;
bh = ext2_bread (dir, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, err);
if (!bh)
return NULL;
if (dir->i_size <= offset) {
if (dir->i_size == 0) {
*err = -ENOENT;
return NULL;
}

ext2_debug ("creating next block\n");

de = (struct ext2_dir_entry *) bh->b_data;
de->inode = 0;
de->rec_len = sb->s_blocksize;
dir->i_size = offset + sb->s_blocksize;
dir->i_dirt = 1;
} else {

ext2_debug ("skipping to next block\n");

de = (struct ext2_dir_entry *) bh->b_data;
}
}
if (!ext2_check_dir_entry ("ext2_add_entry", dir, de, bh,
offset)) {
*err = -ENOENT;
brelse (bh);
return NULL;
}
if (de->inode != 0 && ext2_match (namelen, name, de)) {
*err = -EEXIST;
brelse (bh);
return NULL;
}
if ((de->inode == 0 && de->rec_len >= rec_len) ||
(de->rec_len >= EXT2_DIR_REC_LEN(de->name_len) + rec_len)) {
offset += de->rec_len;
if (de->inode) {
de1 = (struct ext2_dir_entry *) ((char *) de +
EXT2_DIR_REC_LEN(de->name_len));
de1->rec_len = de->rec_len -
EXT2_DIR_REC_LEN(de->name_len);
de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
de = de1;
}
de->inode = 0;
de->name_len = namelen;
memcpy (de->name, name, namelen);
/*
* XXX shouldn't update any times until successful
* completion of syscall, but too many callers depend
* on this.
*
* XXX similarly, too many callers depend on
* ext2_new_inode() setting the times, but error
* recovery deletes the inode, so the worst that can
* happen is that the times are slightly out of date
* and/or different from the directory change time.
*/
dir->i_mtime = dir->i_ctime = CURRENT_TIME;
dir->i_dirt = 1;
dir->i_version = ++event;
mark_buffer_dirty(bh, 1);
*res_dir = de;
*err = 0;
return bh;
}
offset += de->rec_len;
de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
}
brelse (bh);
return NULL;
}

/*
* ext2_delete_entry deletes a directory entry by merging it with the
* previous entry
*/
static int ext2_delete_entry (struct ext2_dir_entry * dir,
struct buffer_head * bh)
{
struct ext2_dir_entry * de, * pde;
int i;

i = 0;
pde = NULL;
de = (struct ext2_dir_entry *) bh->b_data;
while (i < bh->b_size) {
if (!ext2_check_dir_entry ("ext2_delete_entry", NULL,
de, bh, i))
return -EIO;
if (de == dir) {
if (pde)
pde->rec_len += dir->rec_len;
dir->inode = 0;
return 0;
}
i += de->rec_len;
pde = de;
de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
}
return -ENOENT;
}

int ext2_create (struct inode * dir,const char * name, int len, int mode,
struct inode ** result)
{
struct inode * inode;
struct buffer_head * bh;
struct ext2_dir_entry * de;
int err;

*result = NULL;
if (!dir)
return -ENOENT;
inode = ext2_new_inode (dir, mode, &err);
if (!inode) {
iput (dir);
return err;
}
inode->i_op = &ext2_file_inode_operations;
inode->i_mode = mode;
inode->i_dirt = 1;
bh = ext2_add_entry (dir, name, len, &de, &err);
if (!bh) {
inode->i_nlink--;
inode->i_dirt = 1;
iput (inode);
iput (dir);
return err;
}
de->inode = inode->i_ino;
dir->i_version = ++event;
dcache_add(dir, de->name, de->name_len, de->inode);
mark_buffer_dirty(bh, 1);
if (IS_SYNC(dir)) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
brelse (bh);
iput (dir);
*result = inode;
return 0;
}

int ext2_mknod (struct inode * dir, const char * name, int len, int mode,
int rdev)
{
struct inode * inode;
struct buffer_head * bh;
struct ext2_dir_entry * de;
int err;

if (!dir)
return -ENOENT;
bh = ext2_find_entry (dir, name, len, &de);
if (bh) {
brelse (bh);
iput (dir);
return -EEXIST;
}
inode = ext2_new_inode (dir, mode, &err);
if (!inode) {
iput (dir);
return err;
}
inode->i_uid = current->fsuid;
inode->i_mode = mode;
inode->i_op = NULL;
if (S_ISREG(inode->i_mode))
inode->i_op = &ext2_file_inode_operations;
else if (S_ISDIR(inode->i_mode)) {
inode->i_op = &ext2_dir_inode_operations;
if (dir->i_mode & S_ISGID)
inode->i_mode |= S_ISGID;
}
else if (S_ISLNK(inode->i_mode))
inode->i_op = &ext2_symlink_inode_operations;
else if (S_ISCHR(inode->i_mode))
inode->i_op = &chrdev_inode_operations;
else if (S_ISBLK(inode->i_mode))
inode->i_op = &blkdev_inode_operations;
else if (S_ISFIFO(inode->i_mode))
init_fifo(inode);
if (S_ISBLK(mode) || S_ISCHR(mode))
inode->i_rdev = to_kdev_t(rdev);
inode->i_dirt = 1;
bh = ext2_add_entry (dir, name, len, &de, &err);
if (!bh) {
inode->i_nlink--;
inode->i_dirt = 1;
iput (inode);
iput (dir);
return err;
}
de->inode = inode->i_ino;
dir->i_version = ++event;
dcache_add(dir, de->name, de->name_len, de->inode);
mark_buffer_dirty(bh, 1);
if (IS_SYNC(dir)) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
brelse (bh);
iput (dir);
iput (inode);
return 0;
}

int ext2_mkdir (struct inode * dir, const char * name, int len, int mode)
{
struct inode * inode;
struct buffer_head * bh, * dir_block;
struct ext2_dir_entry * de;
int err;

if (!dir)
return -ENOENT;
bh = ext2_find_entry (dir, name, len, &de);
if (bh) {
brelse (bh);
iput (dir);
return -EEXIST;
}
if (dir->i_nlink >= EXT2_LINK_MAX) {
iput (dir);
return -EMLINK;
}
inode = ext2_new_inode (dir, S_IFDIR, &err);
if (!inode) {
iput (dir);
return err;
}
inode->i_op = &ext2_dir_inode_operations;
inode->i_size = inode->i_sb->s_blocksize;
dir_block = ext2_bread (inode, 0, 1, &err);
if (!dir_block) {
iput (dir);
inode->i_nlink--;
inode->i_dirt = 1;
iput (inode);
return err;
}
inode->i_blocks = inode->i_sb->s_blocksize / 512;
de = (struct ext2_dir_entry *) dir_block->b_data;
de->inode = inode->i_ino;
de->name_len = 1;
de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
strcpy (de->name, ".");
de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
de->inode = dir->i_ino;
de->rec_len = inode->i_sb->s_blocksize - EXT2_DIR_REC_LEN(1);
de->name_len = 2;
strcpy (de->name, "..");
inode->i_nlink = 2;
mark_buffer_dirty(dir_block, 1);
brelse (dir_block);
inode->i_mode = S_IFDIR | (mode & S_IRWXUGO & ~current->fs->umask);
if (dir->i_mode & S_ISGID)
inode->i_mode |= S_ISGID;
inode->i_dirt = 1;
bh = ext2_add_entry (dir, name, len, &de, &err);
if (!bh) {
iput (dir);
inode->i_nlink = 0;
inode->i_dirt = 1;
iput (inode);
return err;
}
de->inode = inode->i_ino;
dir->i_version = ++event;
dcache_add(dir, de->name, de->name_len, de->inode);
mark_buffer_dirty(bh, 1);
if (IS_SYNC(dir)) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
dir->i_nlink++;
dir->i_dirt = 1;
iput (dir);
iput (inode);
brelse (bh);
return 0;
}

/*
* routine to check that the specified directory is empty (for rmdir)
*/
static int empty_dir (struct inode * inode)
{
unsigned long offset;
struct buffer_head * bh;
struct ext2_dir_entry * de, * de1;
struct super_block * sb;
int err;

sb = inode->i_sb;
if (inode->i_size < EXT2_DIR_REC_LEN(1) + EXT2_DIR_REC_LEN(2) ||
!(bh = ext2_bread (inode, 0, 0, &err))) {
ext2_warning (inode->i_sb, "empty_dir",
"bad directory (dir #%lu) - no data block",
inode->i_ino);
return 1;
}
de = (struct ext2_dir_entry *) bh->b_data;
de1 = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
if (de->inode != inode->i_ino || !de1->inode ||
strcmp (".", de->name) || strcmp ("..", de1->name)) {
ext2_warning (inode->i_sb, "empty_dir",
"bad directory (dir #%lu) - no `.' or `..'",
inode->i_ino);
return 1;
}
offset = de->rec_len + de1->rec_len;
de = (struct ext2_dir_entry *) ((char *) de1 + de1->rec_len);
while (offset < inode->i_size ) {
if ((void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
brelse (bh);
bh = ext2_bread (inode, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, &err);
if (!bh) {
ext2_error (sb, "empty_dir",
"directory #%lu contains a hole at offset %lu",
inode->i_ino, offset);
offset += sb->s_blocksize;
continue;
}
de = (struct ext2_dir_entry *) bh->b_data;
}
if (!ext2_check_dir_entry ("empty_dir", inode, de, bh,
offset)) {
brelse (bh);
return 1;
}
if (de->inode) {
brelse (bh);
return 0;
}
offset += de->rec_len;
de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
}
brelse (bh);
return 1;
}

int ext2_rmdir (struct inode * dir, const char * name, int len)
{
int retval;
struct inode * inode;
struct buffer_head * bh;
struct ext2_dir_entry * de;

repeat:
if (!dir)
return -ENOENT;
inode = NULL;
bh = ext2_find_entry (dir, name, len, &de);
retval = -ENOENT;
if (!bh)
goto end_rmdir;
retval = -EPERM;
if (!(inode = iget (dir->i_sb, de->inode)))
goto end_rmdir;
if (inode->i_sb->dq_op)
inode->i_sb->dq_op->initialize (inode, -1);
if (inode->i_dev != dir->i_dev)
goto end_rmdir;
if (de->inode != inode->i_ino) {
iput(inode);
brelse(bh);
current->counter = 0;
schedule();
goto repeat;
}
if ((dir->i_mode & S_ISVTX) && !fsuser() &&
current->fsuid != inode->i_uid &&
current->fsuid != dir->i_uid)
goto end_rmdir;
if (inode == dir) /* we may not delete ".", but "../dir" is ok */
goto end_rmdir;
if (!S_ISDIR(inode->i_mode)) {
retval = -ENOTDIR;
goto end_rmdir;
}
down(&inode->i_sem);
if (!empty_dir (inode))
retval = -ENOTEMPTY;
else if (de->inode != inode->i_ino)
retval = -ENOENT;
else {
if (inode->i_count > 1) {
/*
* Are we deleting the last instance of a busy directory?
* Better clean up if so.
*
* Make directory empty (it will be truncated when finally
* dereferenced). This also inhibits ext2_add_entry.
*/
inode->i_size = 0;
}
retval = ext2_delete_entry (de, bh);
dir->i_version = ++event;
}
up(&inode->i_sem);
if (retval)
goto end_rmdir;
mark_buffer_dirty(bh, 1);
if (IS_SYNC(dir)) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
if (inode->i_nlink != 2)
ext2_warning (inode->i_sb, "ext2_rmdir",
"empty directory has nlink!=2 (%d)",
inode->i_nlink);
inode->i_version = ++event;
inode->i_nlink = 0;
inode->i_dirt = 1;
dir->i_nlink--;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
dir->i_dirt = 1;
end_rmdir:
iput (dir);
iput (inode);
brelse (bh);
return retval;
}

int ext2_unlink (struct inode * dir, const char * name, int len)
{
int retval;
struct inode * inode;
struct buffer_head * bh;
struct ext2_dir_entry * de;

repeat:
if (!dir)
return -ENOENT;
retval = -ENOENT;
inode = NULL;
bh = ext2_find_entry (dir, name, len, &de);
if (!bh)
goto end_unlink;
if (!(inode = iget (dir->i_sb, de->inode)))
goto end_unlink;
if (inode->i_sb->dq_op)
inode->i_sb->dq_op->initialize (inode, -1);
retval = -EPERM;
if (S_ISDIR(inode->i_mode))
goto end_unlink;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
goto end_unlink;
if (de->inode != inode->i_ino) {
iput(inode);
brelse(bh);
current->counter = 0;
schedule();
goto repeat;
}
if ((dir->i_mode & S_ISVTX) && !fsuser() &&
current->fsuid != inode->i_uid &&
current->fsuid != dir->i_uid)
goto end_unlink;
if (!inode->i_nlink) {
ext2_warning (inode->i_sb, "ext2_unlink",
"Deleting nonexistent file (%lu), %d",
inode->i_ino, inode->i_nlink);
inode->i_nlink = 1;
}
retval = ext2_delete_entry (de, bh);
if (retval)
goto end_unlink;
dir->i_version = ++event;
mark_buffer_dirty(bh, 1);
if (IS_SYNC(dir)) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
dir->i_ctime = dir->i_mtime = CURRENT_TIME;
dir->i_dirt = 1;
inode->i_nlink--;
inode->i_dirt = 1;
inode->i_ctime = dir->i_ctime;
retval = 0;
end_unlink:
brelse (bh);
iput (inode);
iput (dir);
return retval;
}

int ext2_symlink (struct inode * dir, const char * name, int len,
const char * symname)
{
struct ext2_dir_entry * de;
struct inode * inode = NULL;
struct buffer_head * bh = NULL, * name_block = NULL;
char * link;
int i, err;
int l;
char c;

if (!(inode = ext2_new_inode (dir, S_IFLNK, &err))) {
iput (dir);
return err;
}
inode->i_mode = S_IFLNK | S_IRWXUGO;
inode->i_op = &ext2_symlink_inode_operations;
for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
symname [l]; l++)
;
if (l >= sizeof (inode->u.ext2_i.i_data)) {

ext2_debug ("l=%d, normal symlink\n", l);

name_block = ext2_bread (inode, 0, 1, &err);
if (!name_block) {
iput (dir);
inode->i_nlink--;
inode->i_dirt = 1;
iput (inode);
return err;
}
link = name_block->b_data;
} else {
link = (char *) inode->u.ext2_i.i_data;

ext2_debug ("l=%d, fast symlink\n", l);

}
i = 0;
while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
link[i++] = c;
link[i] = 0;
if (name_block) {
mark_buffer_dirty(name_block, 1);
brelse (name_block);
}
inode->i_size = i;
inode->i_dirt = 1;

bh = ext2_find_entry (dir, name, len, &de);
if (bh) {
inode->i_nlink--;
inode->i_dirt = 1;
iput (inode);
brelse (bh);
iput (dir);
return -EEXIST;
}
bh = ext2_add_entry (dir, name, len, &de, &err);
if (!bh) {
inode->i_nlink--;
inode->i_dirt = 1;
iput (inode);
iput (dir);
return err;
}
de->inode = inode->i_ino;
dir->i_version = ++event;
dcache_add(dir, de->name, de->name_len, de->inode);
mark_buffer_dirty(bh, 1);
if (IS_SYNC(dir)) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
brelse (bh);
iput (dir);
iput (inode);
return 0;
}

int ext2_link (struct inode * oldinode, struct inode * dir,
const char * name, int len)
{
struct ext2_dir_entry * de;
struct buffer_head * bh;
int err;

if (S_ISDIR(oldinode->i_mode)) {
iput (oldinode);
iput (dir);
return -EPERM;
}
if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
iput (oldinode);
iput (dir);
return -EPERM;
}
if (oldinode->i_nlink >= EXT2_LINK_MAX) {
iput (oldinode);
iput (dir);
return -EMLINK;
}
bh = ext2_find_entry (dir, name, len, &de);
if (bh) {
brelse (bh);
iput (dir);
iput (oldinode);
return -EEXIST;
}
bh = ext2_add_entry (dir, name, len, &de, &err);
if (!bh) {
iput (dir);
iput (oldinode);
return err;
}
de->inode = oldinode->i_ino;
dir->i_version = ++event;
dcache_add(dir, de->name, de->name_len, de->inode);
mark_buffer_dirty(bh, 1);
if (IS_SYNC(dir)) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
brelse (bh);
iput (dir);
oldinode->i_nlink++;
oldinode->i_ctime = CURRENT_TIME;
oldinode->i_dirt = 1;
iput (oldinode);
return 0;
}

static int subdir (struct inode * new_inode, struct inode * old_inode)
{
int ino;
int result;

new_inode->i_count++;
result = 0;
for (;;) {
if (new_inode == old_inode) {
result = 1;
break;
}
if (new_inode->i_dev != old_inode->i_dev)
break;
ino = new_inode->i_ino;
if (ext2_lookup (new_inode, "..", 2, &new_inode))
break;
if (new_inode->i_ino == ino)
break;
}
iput (new_inode);
return result;
}

#define PARENT_INO(buffer) \
((struct ext2_dir_entry *) ((char *) buffer + \
((struct ext2_dir_entry *) buffer)->rec_len))->inode

#define PARENT_NAME(buffer) \
((struct ext2_dir_entry *) ((char *) buffer + \
((struct ext2_dir_entry *) buffer)->rec_len))->name

/*
* rename uses retrying to avoid race-conditions: at least they should be
* minimal.
* it tries to allocate all the blocks, then sanity-checks, and if the sanity-
* checks fail, it tries to restart itself again. Very practical - no changes
* are done until we know everything works ok.. and then all the changes can be
* done in one fell swoop when we have claimed all the buffers needed.
*
* Anybody can rename anything with this: the permission checks are left to the
* higher-level routines.
*/
static int do_ext2_rename (struct inode * old_dir, const char * old_name,
int old_len, struct inode * new_dir,
const char * new_name, int new_len)
{
struct inode * old_inode, * new_inode;
struct buffer_head * old_bh, * new_bh, * dir_bh;
struct ext2_dir_entry * old_de, * new_de;
int retval;

goto start_up;
try_again:
if (new_bh && new_de) {
ext2_delete_entry(new_de, new_bh);
new_dir->i_version = ++event;
}
brelse (old_bh);
brelse (new_bh);
brelse (dir_bh);
iput (old_inode);
iput (new_inode);
current->counter = 0;
schedule ();
start_up:
old_inode = new_inode = NULL;
old_bh = new_bh = dir_bh = NULL;
new_de = NULL;
old_bh = ext2_find_entry (old_dir, old_name, old_len, &old_de);
retval = -ENOENT;
if (!old_bh)
goto end_rename;
old_inode = __iget (old_dir->i_sb, old_de->inode, 0); /* don't cross mnt-points */
if (!old_inode)
goto end_rename;
retval = -EPERM;
if ((old_dir->i_mode & S_ISVTX) &&
current->fsuid != old_inode->i_uid &&
current->fsuid != old_dir->i_uid && !fsuser())
goto end_rename;
if (IS_APPEND(old_inode) || IS_IMMUTABLE(old_inode))
goto end_rename;
new_bh = ext2_find_entry (new_dir, new_name, new_len, &new_de);
if (new_bh) {
new_inode = __iget (new_dir->i_sb, new_de->inode, 0); /* no mntp cross */
if (!new_inode) {
brelse (new_bh);
new_bh = NULL;
} else {
if (new_inode->i_sb->dq_op)
new_inode->i_sb->dq_op->initialize (new_inode, -1);
}
}
if (new_inode == old_inode) {
retval = 0;
goto end_rename;
}
if (new_inode && S_ISDIR(new_inode->i_mode)) {
retval = -EISDIR;
if (!S_ISDIR(old_inode->i_mode))
goto end_rename;
retval = -EINVAL;
if (subdir (new_dir, old_inode))
goto end_rename;
retval = -ENOTEMPTY;
if (!empty_dir (new_inode))
goto end_rename;
retval = -EBUSY;
if (new_inode->i_count > 1)
goto end_rename;
}
retval = -EPERM;
if (new_inode && (new_dir->i_mode & S_ISVTX) &&
current->fsuid != new_inode->i_uid &&
current->fsuid != new_dir->i_uid && !fsuser())
goto end_rename;
if (S_ISDIR(old_inode->i_mode)) {
retval = -ENOTDIR;
if (new_inode && !S_ISDIR(new_inode->i_mode))
goto end_rename;
retval = -EINVAL;
if (subdir (new_dir, old_inode))
goto end_rename;
dir_bh = ext2_bread (old_inode, 0, 0, &retval);
if (!dir_bh)
goto end_rename;
if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
goto end_rename;
retval = -EMLINK;
if (!new_inode && new_dir->i_nlink >= EXT2_LINK_MAX)
goto end_rename;
}
if (!new_bh)
new_bh = ext2_add_entry (new_dir, new_name, new_len, &new_de,
&retval);
if (!new_bh)
goto end_rename;
new_dir->i_version = ++event;
/*
* sanity checking before doing the rename - avoid races
*/
if (new_inode && (new_de->inode != new_inode->i_ino))
goto try_again;
if (new_de->inode && !new_inode)
goto try_again;
if (old_de->inode != old_inode->i_ino)
goto try_again;
/*
* ok, that's it
*/
new_de->inode = old_inode->i_ino;
dcache_add(new_dir, new_de->name, new_de->name_len, new_de->inode);
retval = ext2_delete_entry (old_de, old_bh);
if (retval == -ENOENT)
goto try_again;
if (retval)
goto end_rename;
old_dir->i_version = ++event;
if (new_inode) {
new_inode->i_nlink--;
new_inode->i_ctime = CURRENT_TIME;
new_inode->i_dirt = 1;
}
old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
old_dir->i_dirt = 1;
if (dir_bh) {
PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
dcache_add(old_inode, "..", 2, new_dir->i_ino);
mark_buffer_dirty(dir_bh, 1);
old_dir->i_nlink--;
old_dir->i_dirt = 1;
if (new_inode) {
new_inode->i_nlink--;
new_inode->i_dirt = 1;
} else {
new_dir->i_nlink++;
new_dir->i_dirt = 1;
}
}
mark_buffer_dirty(old_bh, 1);
if (IS_SYNC(old_dir)) {
ll_rw_block (WRITE, 1, &old_bh);
wait_on_buffer (old_bh);
}
mark_buffer_dirty(new_bh, 1);
if (IS_SYNC(new_dir)) {
ll_rw_block (WRITE, 1, &new_bh);
wait_on_buffer (new_bh);
}
retval = 0;
end_rename:
brelse (dir_bh);
brelse (old_bh);
brelse (new_bh);
iput (old_inode);
iput (new_inode);
iput (old_dir);
iput (new_dir);
return retval;
}

/*
* Ok, rename also locks out other renames, as they can change the parent of
* a directory, and we don't want any races. Other races are checked for by
* "do_rename()", which restarts if there are inconsistencies.
*
* Note that there is no race between different filesystems: it's only within
* the same device that races occur: many renames can happen at once, as long
* as they are on different partitions.
*
* In the second extended file system, we use a lock flag stored in the memory
* super-block. This way, we really lock other renames only if they occur
* on the same file system
*/
int ext2_rename (struct inode * old_dir, const char * old_name, int old_len,
struct inode * new_dir, const char * new_name, int new_len)
{
int result;

while (old_dir->i_sb->u.ext2_sb.s_rename_lock)
sleep_on (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
old_dir->i_sb->u.ext2_sb.s_rename_lock = 1;
result = do_ext2_rename (old_dir, old_name, old_len, new_dir,
new_name, new_len);
old_dir->i_sb->u.ext2_sb.s_rename_lock = 0;
wake_up (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
return result;
}