tolerate running out of disk blocks
This commit is contained in:
Robert Morris
parent
7d573bae2a
commit
872fa88e8a
40
kernel/fs.c
40
kernel/fs.c
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@ -61,6 +61,7 @@ bzero(int dev, int bno)
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// Blocks.
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// Allocate a zeroed disk block.
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// returns 0 if out of disk space.
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static uint
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balloc(uint dev)
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{
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@ -82,7 +83,8 @@ balloc(uint dev)
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}
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brelse(bp);
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}
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panic("balloc: out of blocks");
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printf("balloc: out of blocks\n");
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return 0;
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}
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// Free a disk block.
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@ -109,8 +111,8 @@ bfree(int dev, uint b)
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// its size, the number of links referring to it, and the
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// list of blocks holding the file's content.
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//
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// The inodes are laid out sequentially on disk at
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// sb.startinode. Each inode has a number, indicating its
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// The inodes are laid out sequentially on disk at block
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// sb.inodestart. Each inode has a number, indicating its
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// position on the disk.
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//
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// The kernel keeps a table of in-use inodes in memory
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@ -374,6 +376,7 @@ iunlockput(struct inode *ip)
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// Return the disk block address of the nth block in inode ip.
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// If there is no such block, bmap allocates one.
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// returns 0 if out of disk space.
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static uint
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bmap(struct inode *ip, uint bn)
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{
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@ -381,22 +384,33 @@ bmap(struct inode *ip, uint bn)
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struct buf *bp;
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if(bn < NDIRECT){
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if((addr = ip->addrs[bn]) == 0)
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ip->addrs[bn] = addr = balloc(ip->dev);
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if((addr = ip->addrs[bn]) == 0){
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addr = balloc(ip->dev);
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if(addr == 0)
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return 0;
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ip->addrs[bn] = addr;
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}
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return addr;
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}
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bn -= NDIRECT;
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if(bn < NINDIRECT){
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// Load indirect block, allocating if necessary.
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if((addr = ip->addrs[NDIRECT]) == 0)
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ip->addrs[NDIRECT] = addr = balloc(ip->dev);
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if((addr = ip->addrs[NDIRECT]) == 0){
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addr = balloc(ip->dev);
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if(addr == 0)
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return 0;
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ip->addrs[NDIRECT] = addr;
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}
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bp = bread(ip->dev, addr);
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a = (uint*)bp->data;
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if((addr = a[bn]) == 0){
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a[bn] = addr = balloc(ip->dev);
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addr = balloc(ip->dev);
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if(addr){
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a[bn] = addr;
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log_write(bp);
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}
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}
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brelse(bp);
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return addr;
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}
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@ -464,7 +478,10 @@ readi(struct inode *ip, int user_dst, uint64 dst, uint off, uint n)
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n = ip->size - off;
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for(tot=0; tot<n; tot+=m, off+=m, dst+=m){
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bp = bread(ip->dev, bmap(ip, off/BSIZE));
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uint addr = bmap(ip, off/BSIZE);
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if(addr == 0)
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break;
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bp = bread(ip->dev, addr);
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m = min(n - tot, BSIZE - off%BSIZE);
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if(either_copyout(user_dst, dst, bp->data + (off % BSIZE), m) == -1) {
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brelse(bp);
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@ -495,7 +512,10 @@ writei(struct inode *ip, int user_src, uint64 src, uint off, uint n)
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return -1;
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for(tot=0; tot<n; tot+=m, off+=m, src+=m){
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bp = bread(ip->dev, bmap(ip, off/BSIZE));
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uint addr = bmap(ip, off/BSIZE);
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if(addr == 0)
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break;
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bp = bread(ip->dev, addr);
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m = min(n - tot, BSIZE - off%BSIZE);
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if(either_copyin(bp->data + (off % BSIZE), user_src, src, m) == -1) {
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brelse(bp);
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@ -2706,6 +2706,49 @@ execout(char *s)
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exit(0);
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}
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// can the kernel tolerate running out of disk space?
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void
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diskfull(char *s)
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{
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int fi;
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int done = 0;
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for(fi = 0; done == 0; fi++){
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char name[32];
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name[0] = 'b';
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name[1] = 'i';
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name[2] = 'g';
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name[3] = '0' + fi;
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name[4] = '\0';
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unlink(name);
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int fd = open(name, O_CREATE|O_RDWR|O_TRUNC);
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if(fd < 0){
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printf("%s: could not create file %s\n", s, name);
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done = 1;
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break;
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}
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for(int i = 0; i < MAXFILE; i++){
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char buf[BSIZE];
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if(write(fd, buf, BSIZE) != BSIZE){
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done = 1;
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close(fd);
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break;
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}
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}
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close(fd);
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}
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for(int i = 0; i < fi; i++){
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char name[32];
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name[0] = 'b';
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name[1] = 'i';
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name[2] = 'g';
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name[3] = '0' + i;
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name[4] = '\0';
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unlink(name);
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}
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}
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//
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// use sbrk() to count how many free physical memory pages there are.
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// touches the pages to force allocation.
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@ -2818,7 +2861,7 @@ main(int argc, char *argv[])
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void (*f)(char *);
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char *s;
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} tests[] = {
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{MAXVAplus, "MAXVAplus"},
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{diskfull, "diskfull"},
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{manywrites, "manywrites"},
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{execout, "execout"},
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{copyin, "copyin"},
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@ -2880,6 +2923,7 @@ main(int argc, char *argv[])
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{dirfile, "dirfile"},
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{iref, "iref"},
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{forktest, "forktest"},
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{MAXVAplus, "MAXVAplus"},
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{bigdir, "bigdir"}, // slow
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{ 0, 0},
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};
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