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92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
/*
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* High-level vfs implementation.
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*
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* Copyright (C) 2008 Bahadir Balban
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*/
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#include <fs.h>
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#include <vfs.h>
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#include <task.h>
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struct list_head vnode_cache;
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struct list_head dentry_cache;
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/*
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* /
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* /boot
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* /boot/images/mm0.axf
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* /boot/images/fs0.axf
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* /boot/images/test0.axf
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* /file.txt
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*/
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struct vfs_mountpoint vfs_root;
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/*
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* Vnodes in the vnode cache have 2 keys. One is their dentry names, the other
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* is their vnum. This one checks the vnode cache by the given vnum first.
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* If nothing is found, it reads the vnode from disk into cache. This is called
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* by system calls since tasks keep an fd-to-vnum table.
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*/
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struct vnode *vfs_lookup_byvnum(struct superblock *sb, unsigned long vnum)
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{
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struct vnode *v;
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int err;
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/* Check the vnode flat list by vnum */
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list_for_each_entry(v, &vnode_cache, cache_list)
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if (v->vnum == vnum)
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return v;
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/* Check the actual filesystem for the vnode */
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v = vfs_alloc_vnode();
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v->vnum = vnum;
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/* Note this only checks given superblock */
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if ((err = sb->ops->read_vnode(sb, v)) < 0) {
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vfs_free_vnode(v);
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return PTR_ERR(err);
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}
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/* Add the vnode back to vnode flat list */
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list_add(&v->cache_list, &vnode_cache);
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return v;
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}
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/*
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* Vnodes in the vnode cache have 2 keys. One is the set of dentry names they
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* have, the other is their vnum. This one checks the vnode cache by the path
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* first. If nothing is found, it reads the vnode from disk into the cache.
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*/
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struct vnode *vfs_lookup_bypath(struct tcb *task, char *path)
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{
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struct vnode *vnstart;
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/* Is it the root or current directory? If so, we already got it. */
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if (!strcmp(path, "/"))
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return task->rootdir;
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if (!strcmp(path, "."))
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return task->curdir;
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/* Do we start from root or curdir? */
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if (path[0] == '/')
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vnstart = task->rootdir;
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else
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vnstart = task->curdir;
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/*
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* This does vfs cache + fs lookup.
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*/
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return generic_vnode_lookup(vnstart, path);
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}
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int vfs_mount_root(struct superblock *sb)
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{
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/* Lookup the root vnode of this superblock.
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* The root superblock has vnode number 0. */
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vfs_root.pivot = vfs_lookup_byvnum(sb, 0);
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vfs_root.sb = sb;
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return 0;
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}
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