URL
https://opencores.org/ocsvn/or1k_old/or1k_old/trunk
Subversion Repositories or1k_old
[/] [or1k_old/] [trunk/] [uclinux/] [uClinux-2.0.x/] [fs/] [file_table.c] - Rev 1782
Compare with Previous | Blame | View Log
/* * linux/fs/file_table.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include <linux/config.h> #include <linux/stddef.h> #include <linux/fs.h> #include <linux/string.h> #include <linux/mm.h> /* * first_file points to a doubly linked list of all file structures in * the system. * nr_files holds the length of this list. */ struct file * first_file = NULL; int nr_files = 0; int max_files = NR_FILE; /* * Insert a new file structure at the head of the list of available ones. */ static inline void insert_file_free(struct file *file) { struct file *next, *prev; next = first_file; first_file = file; file->f_count = 0; prev = next->f_prev; file->f_next = next; next->f_prev = file; file->f_prev = prev; prev->f_next = file; } /* * Remove a file structure from the list of available ones. */ static inline void remove_file_free(struct file *file) { struct file *next, *prev; next = file->f_next; prev = file->f_prev; file->f_next = file->f_prev = NULL; if (first_file == file) first_file = next; next->f_prev = prev; prev->f_next = next; } /* * Insert a file structure at the end of the list of available ones. */ static inline void put_last_free(struct file *file) { struct file *next, *prev; next = first_file; file->f_next = next; prev = next->f_prev; next->f_prev = file; file->f_prev = prev; prev->f_next = file; } /* * Allocate a new memory page for file structures and * insert the new structures into the global list. * Returns 0, if there is no more memory, 1 otherwise. */ static int grow_files(void) { struct file * file; int i; /* * We don't have to clear the page because we only look into * f_count, f_prev and f_next and they get initialized in * insert_file_free. The rest of the file structure is cleared * by get_empty_filp before it is returned. */ file = (struct file *) __get_free_page(GFP_KERNEL); if (!file) return 0; nr_files += i = PAGE_SIZE/sizeof(struct file); if (!first_file) file->f_count = 0, file->f_next = file->f_prev = first_file = file++, i--; for (; i ; i--) insert_file_free(file++); return 1; } unsigned long file_table_init(unsigned long start, unsigned long end) { return start; } /* * Find an unused file structure and return a pointer to it. * Returns NULL, if there are no more free file structures or * we run out of memory. */ struct file * get_empty_filp(void) { int i; int max = max_files; struct file * f; /* * Reserve a few files for the super-user.. */ if (current->euid) max -= 10; /* if the return is taken, we are in deep trouble */ if (!first_file && !grow_files()) return NULL; do { for (f = first_file, i=0; i < nr_files; i++, f = f->f_next) if (!f->f_count) { /* The f_next pointer is followed by the f_prev pointer */ memset(f, 0, offsetof(struct file, f_next)); memset(&f->f_prev + 1, 0, sizeof(*f) - sizeof(f->f_prev) - offsetof(struct file, f_prev)); f->f_count = 1; f->f_version = ++event; first_file = f->f_next; return f; } } while (nr_files < max && grow_files()); return NULL; } #ifdef CONFIG_QUOTA void add_dquot_ref(kdev_t dev, short type) { struct file *filp; int cnt; for (filp = first_file, cnt = 0; cnt < nr_files; cnt++, filp = filp->f_next) { if (!filp->f_count || !filp->f_inode || filp->f_inode->i_dev != dev) continue; if (filp->f_mode & FMODE_WRITE && filp->f_inode->i_sb->dq_op) { filp->f_inode->i_sb->dq_op->initialize(filp->f_inode, type); filp->f_inode->i_flags |= S_WRITE; } } } void reset_dquot_ptrs(kdev_t dev, short type) { struct file *filp; int cnt; for (filp = first_file, cnt = 0; cnt < nr_files; cnt++, filp = filp->f_next) { if (!filp->f_count || !filp->f_inode || filp->f_inode->i_dev != dev) continue; if (IS_WRITABLE(filp->f_inode)) { filp->f_inode->i_dquot[type] = NODQUOT; filp->f_inode->i_flags &= ~S_WRITE; } } } #endif