39 lines
1.8 KiB
C
39 lines
1.8 KiB
C
#ifndef _PROCFS_CONST_H
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#define _PROCFS_CONST_H
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/*
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* The minimum number of inodes depends on a number of factors:
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* - Each statically created inode (e.g., /proc/hz) needs an inode. As of
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* writing, this requires about a dozen inodes.
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* - Deleted inodes that are still in use by VFS must be retained. For deleted
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* directories, all their containing directories up to the root must be
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* retained as well (to allow the user to "cd .." out). VTreeFS already
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* takes care of this. In the case of ProcFS, only PID-based directories can
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* be deleted; no other directories are dynamically created. These
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* directories currently do not contain subdirectories, either. Hence, for
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* deleted open inodes, we need to reserve at most NR_VNODES inodes in the
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* worst case.
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* - In order for getdents to be able to return all PID-based directories,
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* inodes must not be recycled while generating the list of these PID-based
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* directories. In the worst case, this means (NR_TASKS + NR_PROCS) extra
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* inodes.
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* The sum of these is the bare minimum for correct operation in all possible
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* circumstances. In practice, not all open files will be deleted files in
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* ProcFS, and not all process slots will be in use either, so the average use
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* will be a lot less. However, setting the value too low allows for a
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* potential denial-of-service attack by a non-root user.
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*
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* For the moment, we simply set this value to something reasonable.
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*/
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#define NR_INODES ((NR_TASKS + NR_PROCS) * 4)
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/* Various file modes. */
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#define REG_ALL_MODE (S_IFREG | 0444) /* world-readable regular */
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#define DIR_ALL_MODE (S_IFDIR | 0555) /* world-accessible directory */
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#define LNK_ALL_MODE (S_IFLNK | 0777) /* symbolic link */
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/* Size of the I/O buffer. */
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#define BUF_SIZE 4097 /* 4KB+1 (see buf.c) */
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#endif /* _PROCFS_CONST_H */
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