Imbus/xv6-riscv-kernel
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tolerate running out of disk blocks

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This commit is contained in:
Robert Morris 2022-08-10 06:13:52 -04:00
parent 7d573bae2a
commit 872fa88e8a
2 changed files with 76 additions and 12 deletions
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42
kernel/fs.c
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@ -61,6 +61,7 @@ bzero(int dev, int bno)
// Blocks.
// Allocate a zeroed disk block.
// returns 0 if out of disk space.
static uint
balloc(uint dev)
{
@ -82,7 +83,8 @@ balloc(uint dev)
}
brelse(bp);
}
panic("balloc: out of blocks");
printf("balloc: out of blocks\n");
return 0;
}
// Free a disk block.
@ -109,8 +111,8 @@ bfree(int dev, uint b)
// its size, the number of links referring to it, and the
// list of blocks holding the file's content.
//
// The inodes are laid out sequentially on disk at
// sb.startinode. Each inode has a number, indicating its
// The inodes are laid out sequentially on disk at block
// sb.inodestart. Each inode has a number, indicating its
// position on the disk.
//
// The kernel keeps a table of in-use inodes in memory
@ -374,6 +376,7 @@ iunlockput(struct inode *ip)
// Return the disk block address of the nth block in inode ip.
// If there is no such block, bmap allocates one.
// returns 0 if out of disk space.
static uint
bmap(struct inode *ip, uint bn)
{
@ -381,21 +384,32 @@ bmap(struct inode *ip, uint bn)
struct buf *bp;
if(bn < NDIRECT){
if((addr = ip->addrs[bn]) == 0)
ip->addrs[bn] = addr = balloc(ip->dev);
if((addr = ip->addrs[bn]) == 0){
addr = balloc(ip->dev);
if(addr == 0)
return 0;
ip->addrs[bn] = addr;
}
return addr;
}
bn -= NDIRECT;
if(bn < NINDIRECT){
// Load indirect block, allocating if necessary.
if((addr = ip->addrs[NDIRECT]) == 0)
ip->addrs[NDIRECT] = addr = balloc(ip->dev);
if((addr = ip->addrs[NDIRECT]) == 0){
addr = balloc(ip->dev);
if(addr == 0)
return 0;
ip->addrs[NDIRECT] = addr;
}
bp = bread(ip->dev, addr);
a = (uint*)bp->data;
if((addr = a[bn]) == 0){
a[bn] = addr = balloc(ip->dev);
log_write(bp);
addr = balloc(ip->dev);
if(addr){
a[bn] = addr;
log_write(bp);
}
}
brelse(bp);
return addr;
@ -464,7 +478,10 @@ readi(struct inode *ip, int user_dst, uint64 dst, uint off, uint n)
n = ip->size - off;
for(tot=0; tot<n; tot+=m, off+=m, dst+=m){
bp = bread(ip->dev, bmap(ip, off/BSIZE));
uint addr = bmap(ip, off/BSIZE);
if(addr == 0)
break;
bp = bread(ip->dev, addr);
m = min(n - tot, BSIZE - off%BSIZE);
if(either_copyout(user_dst, dst, bp->data + (off % BSIZE), m) == -1) {
brelse(bp);
@ -495,7 +512,10 @@ writei(struct inode *ip, int user_src, uint64 src, uint off, uint n)
return -1;
for(tot=0; tot<n; tot+=m, off+=m, src+=m){
bp = bread(ip->dev, bmap(ip, off/BSIZE));
uint addr = bmap(ip, off/BSIZE);
if(addr == 0)
break;
bp = bread(ip->dev, addr);
m = min(n - tot, BSIZE - off%BSIZE);
if(either_copyin(bp->data + (off % BSIZE), user_src, src, m) == -1) {
brelse(bp);