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author | Frans Kaashoek <[email protected]> | 2011-08-26 10:08:29 -0400 |
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committer | Frans Kaashoek <[email protected]> | 2011-08-26 10:08:29 -0400 |
commit | 3a5fa7ed9020eaf8ab843a16d26db7393b2ec072 (patch) | |
tree | bfa4ad4ae03d7d21796bacaa7eab8e3d3e4ab365 /fs.c | |
parent | 8a9b6dbd4468f6312f1d07226a623879f970bd4b (diff) | |
download | xv6-labs-3a5fa7ed9020eaf8ab843a16d26db7393b2ec072.tar.gz xv6-labs-3a5fa7ed9020eaf8ab843a16d26db7393b2ec072.tar.bz2 xv6-labs-3a5fa7ed9020eaf8ab843a16d26db7393b2ec072.zip |
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)
Diffstat (limited to 'fs.c')
-rw-r--r-- | fs.c | 32 |
1 files changed, 16 insertions, 16 deletions
@@ -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; tot<n; tot+=m, off+=m, src+=m){ bp = bread(ip->dev, bmap(ip, off/BSIZE)); |