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authorFrans Kaashoek <[email protected]>2011-08-29 17:18:40 -0400
committerFrans Kaashoek <[email protected]>2011-08-29 17:18:40 -0400
commit1ddfbbb194e3aa668b33469eb547132a7a7f940a (patch)
tree41ad0ae10ef2743c6e9433e711358dede77ce041 /fs.c
parent22f7db5336cb20c82eb1ffa45c0ef63825442c95 (diff)
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Revert "Introduce and use sleeplocks instead of BUSY flags"
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 3a5fa7ed9020eaf8ab843a16d26db7393b2ec072. Conflicts: defs.h file.c file.h
Diffstat (limited to 'fs.c')
-rw-r--r--fs.c32
1 files changed, 16 insertions, 16 deletions
diff --git a/fs.c b/fs.c
index 6bfe963..b755c78 100644
--- a/fs.c
+++ b/fs.c
@@ -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));