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fix iput() to more obviously avoid deadlock

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This commit is contained in:
Robert Morris 2017-08-08 14:19:54 -04:00
parent 1c7aa96005
commit a4ee6f7de3
1 changed files with 9 additions and 7 deletions
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16
fs.c
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@ -329,20 +329,22 @@ iunlock(struct inode *ip)
void void
iput(struct inode *ip) iput(struct inode *ip)
{ {
acquire(&icache.lock); acquiresleep(&ip->lock);
if(ip->ref == 1){ if(ip->valid && ip->nlink == 0){
acquiresleep(&ip->lock); acquire(&icache.lock);
if(ip->valid && ip->nlink == 0){ int r = ip->ref;
release(&icache.lock);
if(r == 1){
// inode has no links and no other references: truncate and free. // inode has no links and no other references: truncate and free.
release(&icache.lock);
itrunc(ip); itrunc(ip);
ip->type = 0; ip->type = 0;
iupdate(ip); iupdate(ip);
ip->valid = 0; ip->valid = 0;
acquire(&icache.lock);
} }
releasesleep(&ip->lock);
} }
releasesleep(&ip->lock);
acquire(&icache.lock);
ip->ref--; ip->ref--;
release(&icache.lock); release(&icache.lock);
} }