Imbus/xv6-riscv-kernel
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Revert "Introduce and use sleeplocks instead of BUSY flags"

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My changes have a race with re-used bufs and the code doesn't seem to get shorter
Keep the changes that fixed ip->off race

This reverts commit 3a5fa7ed90.

Conflicts:

	defs.h
	file.c
	file.h
This commit is contained in:
Frans Kaashoek 2011-08-29 17:18:40 -04:00
parent 22f7db5336
commit 1ddfbbb194
12 changed files with 61 additions and 105 deletions
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32
fs.c
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@ -113,8 +113,11 @@ bfree(int dev, uint b)
// It is an error to use an inode without holding a reference to it.
//
// Processes are only allowed to read and write inode
// metadata and contents when holding the inode's sleeplock.
// Callers are responsible for locking
// metadata and contents when holding the inode's lock,
// represented by the I_BUSY flag in the in-memory copy.
// Because inode locks are held during disk accesses,
// they are implemented using a flag rather than with
// spin locks. Callers are responsible for locking
// inodes before passing them to routines in this file; leaving
// this responsibility with the caller makes it possible for them
// to create arbitrarily-sized atomic operations.
@ -213,7 +216,6 @@ iget(uint dev, uint inum)
ip->inum = inum;
ip->ref = 1;
ip->flags = 0;
initsleeplock(&ip->sleeplock);
release(&icache.lock);
return ip;
@ -230,7 +232,7 @@ idup(struct inode *ip)
return ip;
}
// Acquire the sleeplock for a given inode.
// Lock the given inode.
void
ilock(struct inode *ip)
{
@ -241,7 +243,9 @@ ilock(struct inode *ip)
panic("ilock");
acquire(&icache.lock);
acquire_sleeplock(&ip->sleeplock, &icache.lock);
while(ip->flags & I_BUSY)
sleep(ip, &icache.lock);
ip->flags |= I_BUSY;
release(&icache.lock);
if(!(ip->flags & I_VALID)){
@ -264,11 +268,12 @@ ilock(struct inode *ip)
void
iunlock(struct inode *ip)
{
if(ip == 0 || !acquired_sleeplock(&ip->sleeplock) || ip->ref < 1)
if(ip == 0 || !(ip->flags & I_BUSY) || ip->ref < 1)
panic("iunlock");
acquire(&icache.lock);
release_sleeplock(&ip->sleeplock);
ip->flags &= ~I_BUSY;
wakeup(ip);
release(&icache.lock);
}
@ -279,15 +284,14 @@ iput(struct inode *ip)
acquire(&icache.lock);
if(ip->ref == 1 && (ip->flags & I_VALID) && ip->nlink == 0){
// inode is no longer used: truncate and free inode.
if(acquired_sleeplock(&ip->sleeplock))
if(ip->flags & I_BUSY)
panic("iput busy");
acquire_sleeplock(&ip->sleeplock, &icache.lock);
ip->flags |= I_BUSY;
release(&icache.lock);
itrunc(ip);
ip->type = 0;
iupdate(ip);
acquire(&icache.lock);
release_sleeplock(&ip->sleeplock);
ip->flags = 0;
wakeup(ip);
}
@ -429,14 +433,10 @@ writei(struct inode *ip, char *src, uint off, uint n)
return devsw[ip->major].write(ip, src, n);
}
if(off > ip->size || off + n < off) {
panic("writei1");
if(off > ip->size || off + n < off)
return -1;
}
if(off + n > MAXFILE*BSIZE) {
panic("writei2");
if(off + n > MAXFILE*BSIZE)
return -1;
}
for(tot=0; tot<n; tot+=m, off+=m, src+=m){
bp = bread(ip->dev, bmap(ip, off/BSIZE));