Midterm Exam - Stanford Secure Computer Systems Group
Midterm Exam - Stanford Secure Computer Systems Group
Midterm Exam - Stanford Secure Computer Systems Group
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– p. 16/16<br />
Fixing corruption – fsck<br />
• Summary info usually bad after crash<br />
- Scan to check free block map, block/inode counts<br />
• System may have corrupt inodes (not simple crash)<br />
- Bad block numbers, cross-allocation, etc.<br />
- Do sanity check, clear inodes with garbage<br />
toÐÓ×Ø·ÓÙÒ<br />
- Count number of directory entries verify link count, if no<br />
entries but count ≠ 0, move<br />
- Make sure size and used data counts match blocks<br />
• Fields in inodes may be wrong<br />
• Directories may be bad<br />
- Holes illegal,ºandººmust be valid, . . .<br />
- All directories must be reachable
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