diff options
Diffstat (limited to 'fs.c')
| -rw-r--r-- | fs.c | 15 |
1 files changed, 9 insertions, 6 deletions
@@ -155,10 +155,10 @@ bfree(int dev, uint b) // have locked the inodes involved; this lets callers create // multi-step atomic operations. // -// The icache.lock spin-lock defends ip->ref, ip->dev, and ip->inum. -// Since ip->ref indicates whether an icache entry is free, the -// icache.lock defends icache allocation. icache.lock also defends -// all fields of an unallocated icache entry, during allocation. +// The icache.lock spin-lock defends the allocation of icache +// entries. Since ip->ref indicates whether an entry is free, +// and ip->dev and ip->inum indicate which i-node an entry +// holds, one must hold icache.lock while using any of those fields. // // An ip->lock sleep-lock defends all ip-> fields other than ref, // dev, and inum. One must hold ip->lock in order to @@ -189,8 +189,9 @@ iinit(int dev) static struct inode* iget(uint dev, uint inum); //PAGEBREAK! -// Allocate a new inode with the given type on device dev. -// A free inode has a type of zero. +// Allocate an inode on device dev. +// Give it type type. +// Returns an unlocked but allocated and referenced inode. struct inode* ialloc(uint dev, short type) { @@ -214,6 +215,8 @@ ialloc(uint dev, short type) } // Copy a modified in-memory inode to disk. +// Must be called after every change to an ip->xxx field +// that lives on disk, since i-node cache is write-through. // Caller must hold ip->lock. void iupdate(struct inode *ip) |