namei returns locked parent dir inode for create / unlink
don't hold fd table lock across idecref() (latter does block i/o) idecref calls iput() in case last ref -> freeing inode dir size is 512 * # blocks, so readi/writei &c work unlink deletes dirent even if ip->nlink > 0
This commit is contained in:
rtm
parent
c372e8dc34
commit
211ff0c67e
7 changed files with 122 additions and 84 deletions
15
Notes
15
Notes
|
|
@ -365,3 +365,18 @@ two bugs in unlink: don't just return if nlink > 0,
|
|||
and search for name, not inum
|
||||
is there a create/create race for same file name?
|
||||
resulting in two entries w/ same name in directory?
|
||||
|
||||
namei
|
||||
return just inode
|
||||
return offset in dir where found, w/ dir locked, for unlink
|
||||
return dir locked, for mknod
|
||||
|
||||
is the offset alone useful? how do I read/write it?
|
||||
|
||||
test: one process unlinks a file while another links to it
|
||||
test: simultaneous create of same file
|
||||
test: one process opens a file while another deletes it
|
||||
|
||||
oy, mkfs wants dir size to be last written entry, but i
|
||||
want it to be nblocks*512
|
||||
maybe fix kernel code to handle former
|
||||
|
|
|
|||
2
defs.h
2
defs.h
|
|
@ -116,7 +116,7 @@ void ilock(struct inode *ip);
|
|||
void iunlock(struct inode *ip);
|
||||
void idecref(struct inode *ip);
|
||||
void iput(struct inode *ip);
|
||||
struct inode * namei(char *path, uint *);
|
||||
struct inode * namei(char *path, int, uint *);
|
||||
void stati(struct inode *ip, struct stat *st);
|
||||
int readi(struct inode *ip, char *xdst, uint off, uint n);
|
||||
int writei(struct inode *ip, char *addr, uint off, uint n);
|
||||
|
|
|
|||
20
fd.c
20
fd.c
|
|
@ -108,18 +108,22 @@ fd_close(struct fd *fd)
|
|||
panic("fd_close");
|
||||
|
||||
if(--fd->ref == 0){
|
||||
if(fd->type == FD_PIPE){
|
||||
pipe_close(fd->pipe, fd->writeable);
|
||||
} else if(fd->type == FD_FILE){
|
||||
idecref(fd->ip);
|
||||
struct fd dummy = *fd;
|
||||
|
||||
fd->ref = 0;
|
||||
fd->type = FD_CLOSED;
|
||||
release(&fd_table_lock);
|
||||
|
||||
if(dummy.type == FD_PIPE){
|
||||
pipe_close(dummy.pipe, dummy.writeable);
|
||||
} else if(dummy.type == FD_FILE){
|
||||
idecref(dummy.ip);
|
||||
} else {
|
||||
panic("fd_close");
|
||||
}
|
||||
fd->ref = 0;
|
||||
fd->type = FD_CLOSED;
|
||||
} else {
|
||||
release(&fd_table_lock);
|
||||
}
|
||||
|
||||
release(&fd_table_lock);
|
||||
}
|
||||
|
||||
int
|
||||
|
|
|
|||
157
fs.c
157
fs.c
|
|
@ -286,14 +286,8 @@ iput(struct inode *ip)
|
|||
void
|
||||
idecref(struct inode *ip)
|
||||
{
|
||||
acquire(&inode_table_lock);
|
||||
|
||||
if(ip->count < 1)
|
||||
panic("idecref");
|
||||
|
||||
ip->count -= 1;
|
||||
|
||||
release(&inode_table_lock);
|
||||
ilock(ip);
|
||||
iput(ip);
|
||||
}
|
||||
|
||||
void
|
||||
|
|
@ -376,34 +370,37 @@ writei(struct inode *ip, char *addr, uint off, uint n)
|
|||
}
|
||||
}
|
||||
|
||||
// look up a path name, in one of three modes.
|
||||
// NAMEI_LOOKUP: return locked target inode.
|
||||
// NAMEI_CREATE: return locked parent inode.
|
||||
// but return 0 if name does exist.
|
||||
// NAMEI_DELETE: return locked parent inode, offset of dirent in *ret_off.
|
||||
// return 0 if name doesn't exist.
|
||||
struct inode *
|
||||
namei(char *path, uint *ret_pinum)
|
||||
namei(char *path, int mode, uint *ret_off)
|
||||
{
|
||||
struct inode *dp;
|
||||
char *cp = path;
|
||||
char *cp = path, *cp1;
|
||||
uint off, dev;
|
||||
struct buf *bp;
|
||||
struct dirent *ep;
|
||||
int i;
|
||||
int i, atend;
|
||||
unsigned ninum;
|
||||
unsigned pinum;
|
||||
|
||||
|
||||
dp = iget(rootdev, 1);
|
||||
pinum = dp->inum;
|
||||
|
||||
while(*cp == '/')
|
||||
cp++;
|
||||
|
||||
while(1){
|
||||
if(*cp == '\0') {
|
||||
if (ret_pinum)
|
||||
*ret_pinum = pinum;
|
||||
return dp;
|
||||
if(*cp == '\0'){
|
||||
if(mode == NAMEI_LOOKUP)
|
||||
return dp;
|
||||
iput(dp);
|
||||
return 0;
|
||||
}
|
||||
|
||||
if(dp->type != T_DIR){
|
||||
if (ret_pinum)
|
||||
*ret_pinum = pinum;
|
||||
iput(dp);
|
||||
return 0;
|
||||
}
|
||||
|
|
@ -419,6 +416,7 @@ namei(char *path, uint *ret_pinum)
|
|||
if(cp[i] != ep->name[i])
|
||||
break;
|
||||
if((cp[i] == '\0' || cp[i] == '/') && (i >= DIRSIZ || ep->name[i] == '\0')){
|
||||
off += (uchar*)ep - bp->data;
|
||||
ninum = ep->inum;
|
||||
brelse(bp);
|
||||
cp += i;
|
||||
|
|
@ -427,14 +425,22 @@ namei(char *path, uint *ret_pinum)
|
|||
}
|
||||
brelse(bp);
|
||||
}
|
||||
atend = 1;
|
||||
for(cp1 = cp; *cp1; cp1++)
|
||||
if(*cp1 == '/')
|
||||
atend = 0;
|
||||
if(mode == NAMEI_CREATE && atend)
|
||||
return dp;
|
||||
|
||||
iput(dp);
|
||||
if (ret_pinum)
|
||||
*ret_pinum = pinum;
|
||||
return 0;
|
||||
|
||||
found:
|
||||
if(mode == NAMEI_DELETE && *cp == '\0'){
|
||||
*ret_off = off;
|
||||
return dp;
|
||||
}
|
||||
dev = dp->dev;
|
||||
pinum = dp->inum;
|
||||
iput(dp);
|
||||
dp = iget(dev, ninum);
|
||||
if(dp->type == 0 || dp->nlink < 1)
|
||||
|
|
@ -453,6 +459,9 @@ wdir(struct inode *dp, char *name, uint ino)
|
|||
int i;
|
||||
int lb;
|
||||
|
||||
if(dp->size % BSIZE)
|
||||
dp->size += (BSIZE - dp->size % BSIZE);
|
||||
|
||||
for(off = 0; off < dp->size; off += BSIZE) {
|
||||
bp = bread(dp->dev, bmap(dp, off / BSIZE));
|
||||
for(ep = (struct dirent *) bp->data;
|
||||
|
|
@ -469,14 +478,16 @@ wdir(struct inode *dp, char *name, uint ino)
|
|||
}
|
||||
dp->addrs[lb] = balloc(dp->dev);
|
||||
bp = bread(dp->dev, dp->addrs[lb]);
|
||||
memset(bp->data, 0, BSIZE);
|
||||
ep = (struct dirent *) (bp->data);
|
||||
dp->size += BSIZE;
|
||||
|
||||
found:
|
||||
ep->inum = ino;
|
||||
for(i = 0; i < DIRSIZ && name[i]; i++)
|
||||
ep->name[i] = name[i];
|
||||
for( ; i < DIRSIZ; i++)
|
||||
ep->name[i] = '\0';
|
||||
dp->size += sizeof(struct dirent);
|
||||
bwrite (bp, bmap(dp, off/BSIZE)); // write directory block
|
||||
brelse(bp);
|
||||
iupdate(dp);
|
||||
|
|
@ -486,15 +497,12 @@ struct inode *
|
|||
mknod(char *cp, short type, short major, short minor)
|
||||
{
|
||||
struct inode *ip, *dp;
|
||||
uint pinum = 0;
|
||||
|
||||
cprintf("mknod: %s %d %d %d\n", cp, type, major, minor);
|
||||
|
||||
if ((ip = namei(cp, &pinum)) != 0) {
|
||||
iput(ip);
|
||||
if ((dp = namei(cp, NAMEI_CREATE, 0)) == 0)
|
||||
return 0;
|
||||
}
|
||||
dp = iget(rootdev, pinum);
|
||||
|
||||
ip = ialloc(dp->dev, type);
|
||||
if (ip == 0) {
|
||||
iput(dp);
|
||||
|
|
@ -515,74 +523,81 @@ mknod(char *cp, short type, short major, short minor)
|
|||
int
|
||||
unlink(char *cp)
|
||||
{
|
||||
struct inode *ip;
|
||||
struct inode *dp;
|
||||
struct dirent *ep = 0;
|
||||
int off;
|
||||
struct buf *bp = 0;
|
||||
uint pinum;
|
||||
|
||||
struct inode *ip, *dp;
|
||||
struct dirent de;
|
||||
uint off, inum, cc;
|
||||
|
||||
if ((ip = namei(cp, &pinum)) == 0) {
|
||||
cprintf("unlink(%s)\n", cp);
|
||||
|
||||
if ((dp = namei(cp, NAMEI_DELETE, &off)) == 0) {
|
||||
cprintf("unlink(%s) it doesn't exist\n", cp);
|
||||
return -1;
|
||||
}
|
||||
|
||||
ip->nlink--;
|
||||
if (ip->nlink > 0) {
|
||||
iput(ip);
|
||||
return 0;
|
||||
if((cc = readi(dp, (char*)&de, off, sizeof(de))) != sizeof(de) ||
|
||||
de.inum == 0){
|
||||
cprintf("off %d dp->size %d cc %d de.inum %d",
|
||||
off, dp->size, cc, de.inum);
|
||||
panic("unlink no entry");
|
||||
}
|
||||
inum = de.inum;
|
||||
cprintf("dinum %d off %d de %s/%d\n",
|
||||
dp->inum, off, de.name, de.inum);
|
||||
|
||||
dp = iget(rootdev, pinum);
|
||||
for(off = 0; off < dp->size; off += BSIZE) {
|
||||
bp = bread(dp->dev, bmap(dp, off / BSIZE));
|
||||
for(ep = (struct dirent *) bp->data;
|
||||
ep < (struct dirent *) (bp->data + BSIZE);
|
||||
ep++){
|
||||
if(ep->inum == ip->inum) {
|
||||
goto found;
|
||||
}
|
||||
}
|
||||
brelse(bp);
|
||||
}
|
||||
panic("unlink: entry doesn't exist\n");
|
||||
memset(&de, 0, sizeof(de));
|
||||
if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
|
||||
panic("unlink dir write");
|
||||
|
||||
found:
|
||||
ep->inum = 0;
|
||||
memset(ep->name, '\0', DIRSIZ);
|
||||
bwrite (bp, bmap(dp, off/BSIZE)); // write directory block
|
||||
brelse(bp);
|
||||
dp->size -= sizeof(struct dirent);
|
||||
iupdate (dp);
|
||||
iupdate(dp);
|
||||
iput(dp);
|
||||
|
||||
ip = iget(dp->dev, inum);
|
||||
if(ip == 0)
|
||||
panic("unlink no inode");
|
||||
|
||||
ip->nlink--;
|
||||
|
||||
iupdate(ip);
|
||||
iput(ip);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
int
|
||||
link(char *name1, char *name2)
|
||||
{
|
||||
struct inode *ip, *dp, *xip;
|
||||
uint pinum = 0;
|
||||
struct inode *ip, *dp;
|
||||
|
||||
cprintf("link(%s, %s)\n", name1, name2);
|
||||
|
||||
if ((xip = namei(name2, &pinum)) != 0) {
|
||||
cprintf(" failed %s exists\n", name2);
|
||||
iput(xip);
|
||||
return -1;
|
||||
}
|
||||
|
||||
if ((ip = namei(name1, &pinum)) == 0){
|
||||
if ((ip = namei(name1, NAMEI_LOOKUP, 0)) == 0){
|
||||
cprintf(" failed %s does not exist\n", name1);
|
||||
return -1;
|
||||
}
|
||||
if(ip->type == T_DIR){
|
||||
cprintf(" failed %s is a dir\n", name1);
|
||||
iput(ip);
|
||||
return -1;
|
||||
}
|
||||
|
||||
iunlock(ip);
|
||||
|
||||
if ((dp = namei(name2, NAMEI_CREATE, 0)) == 0) {
|
||||
cprintf(" failed %s exists\n", name2);
|
||||
idecref(ip);
|
||||
return -1;
|
||||
}
|
||||
if(dp->dev != ip->dev){
|
||||
cprintf(" cross-device link\n");
|
||||
idecref(ip);
|
||||
iput(dp);
|
||||
return -1;
|
||||
}
|
||||
|
||||
ilock(ip);
|
||||
ip->nlink += 1;
|
||||
iupdate (ip);
|
||||
|
||||
dp = iget(rootdev, pinum);
|
||||
wdir(dp, name2, ip->inum);
|
||||
iput(dp);
|
||||
iput(ip);
|
||||
|
|
|
|||
4
fsvar.h
4
fsvar.h
|
|
@ -14,3 +14,7 @@ struct inode {
|
|||
};
|
||||
|
||||
extern uint rootdev;
|
||||
|
||||
#define NAMEI_LOOKUP 1
|
||||
#define NAMEI_CREATE 2
|
||||
#define NAMEI_DELETE 3
|
||||
|
|
|
|||
|
|
@ -228,7 +228,7 @@ sys_open(void)
|
|||
return -1;
|
||||
if((l = checkstring(arg0)) < 0)
|
||||
return -1;
|
||||
if((ip = namei(cp->mem + arg0, 0)) == 0) {
|
||||
if((ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0)) == 0) {
|
||||
if (arg1 & O_CREATE) {
|
||||
if (l >= DIRSIZ)
|
||||
return -1;
|
||||
|
|
@ -356,7 +356,7 @@ sys_exec(void)
|
|||
return -1;
|
||||
if(checkstring(arg0) < 0)
|
||||
return -1;
|
||||
ip = namei(cp->mem + arg0, 0);
|
||||
ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0);
|
||||
if(ip == 0)
|
||||
return -1;
|
||||
|
||||
|
|
@ -494,7 +494,7 @@ sys_block(void)
|
|||
ip->type, ip->nlink, ip->size, ip->addrs[0]);
|
||||
iput(ip);
|
||||
|
||||
ip = namei(".././//./../usertests", 0);
|
||||
ip = namei(".././//./../usertests", NAMEI_LOOKUP, 0);
|
||||
if(ip){
|
||||
cprintf("namei(usertests): %d %d %d %d %d %d %d %d\n",
|
||||
ip->dev, ip->inum, ip->count, ip->busy,
|
||||
|
|
|
|||
|
|
@ -231,7 +231,7 @@ void
|
|||
createdelete()
|
||||
{
|
||||
int pid, i, fd;
|
||||
int n = 10; // for now, fit in one directory block
|
||||
int n = 20;
|
||||
char name[32];
|
||||
|
||||
pid = fork();
|
||||
|
|
|
|||
Loading…
Reference in a new issue