From 3a5fa7ed9020eaf8ab843a16d26db7393b2ec072 Mon Sep 17 00:00:00 2001 From: Frans Kaashoek Date: Fri, 26 Aug 2011 10:08:29 -0400 Subject: Introduce and use sleeplocks instead of BUSY flags Remove I_BUSY, B_BUSY, and intrans defs and usages One spinlock per buf to avoid ugly loop in bget fix race in filewrite (don't update f->off after releasing lock) --- fs.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) (limited to 'fs.c') diff --git a/fs.c b/fs.c index b755c78..6bfe963 100644 --- a/fs.c +++ b/fs.c @@ -113,11 +113,8 @@ 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 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 +// metadata and contents when holding the inode's sleeplock. +// 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. @@ -216,6 +213,7 @@ iget(uint dev, uint inum) ip->inum = inum; ip->ref = 1; ip->flags = 0; + initsleeplock(&ip->sleeplock); release(&icache.lock); return ip; @@ -232,7 +230,7 @@ idup(struct inode *ip) return ip; } -// Lock the given inode. +// Acquire the sleeplock for a given inode. void ilock(struct inode *ip) { @@ -243,9 +241,7 @@ ilock(struct inode *ip) panic("ilock"); acquire(&icache.lock); - while(ip->flags & I_BUSY) - sleep(ip, &icache.lock); - ip->flags |= I_BUSY; + acquire_sleeplock(&ip->sleeplock, &icache.lock); release(&icache.lock); if(!(ip->flags & I_VALID)){ @@ -268,12 +264,11 @@ ilock(struct inode *ip) void iunlock(struct inode *ip) { - if(ip == 0 || !(ip->flags & I_BUSY) || ip->ref < 1) + if(ip == 0 || !acquired_sleeplock(&ip->sleeplock) || ip->ref < 1) panic("iunlock"); acquire(&icache.lock); - ip->flags &= ~I_BUSY; - wakeup(ip); + release_sleeplock(&ip->sleeplock); release(&icache.lock); } @@ -284,14 +279,15 @@ 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(ip->flags & I_BUSY) + if(acquired_sleeplock(&ip->sleeplock)) panic("iput busy"); - ip->flags |= I_BUSY; + acquire_sleeplock(&ip->sleeplock, &icache.lock); release(&icache.lock); itrunc(ip); ip->type = 0; iupdate(ip); acquire(&icache.lock); + release_sleeplock(&ip->sleeplock); ip->flags = 0; wakeup(ip); } @@ -433,10 +429,14 @@ 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) + if(off > ip->size || off + n < off) { + panic("writei1"); return -1; - if(off + n > MAXFILE*BSIZE) + } + if(off + n > MAXFILE*BSIZE) { + panic("writei2"); return -1; + } for(tot=0; totdev, bmap(ip, off/BSIZE)); -- cgit v1.2.3