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inode numbering: change libfs sb creation routines to avoid collisions with their root inodes
This patch makes it so that simple_fill_super and get_sb_pseudo assign their root inodes to be number 1. It also fixes up a couple of callers of simple_fill_super that were passing in files arrays that had an index at number 1, and adds a warning for any caller that sends in such an array. It would have been nice to have made it so that it wasn't possible to make such a collision, but some callers need to be able to control what inode number their entries get, so I think this is the best that can be done. Signed-off-by: Jeff Layton <jlayton@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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parent
866b04fccb
commit
1a1c9bb433
3 changed files with 26 additions and 3 deletions
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@ -523,7 +523,7 @@ static int ipathfs_fill_super(struct super_block *sb, void *data,
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int ret;
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static struct tree_descr files[] = {
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[1] = {"atomic_stats", &atomic_stats_ops, S_IRUGO},
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[2] = {"atomic_stats", &atomic_stats_ops, S_IRUGO},
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{""},
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};
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@ -727,8 +727,8 @@ static const struct super_operations s_ops = {
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static int bm_fill_super(struct super_block * sb, void * data, int silent)
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{
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static struct tree_descr bm_files[] = {
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[1] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
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[2] = {"register", &bm_register_operations, S_IWUSR},
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[2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
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[3] = {"register", &bm_register_operations, S_IWUSR},
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/* last one */ {""}
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};
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int err = simple_fill_super(sb, 0x42494e4d, bm_files);
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23
fs/libfs.c
23
fs/libfs.c
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@ -220,6 +220,12 @@ int get_sb_pseudo(struct file_system_type *fs_type, char *name,
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root = new_inode(s);
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if (!root)
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goto Enomem;
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/*
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* since this is the first inode, make it number 1. New inodes created
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* after this must take care not to collide with it (by passing
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* max_reserved of 1 to iunique).
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*/
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root->i_ino = 1;
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root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
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root->i_uid = root->i_gid = 0;
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root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
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@ -360,6 +366,11 @@ int simple_commit_write(struct file *file, struct page *page,
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return 0;
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}
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/*
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* the inodes created here are not hashed. If you use iunique to generate
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* unique inode values later for this filesystem, then you must take care
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* to pass it an appropriate max_reserved value to avoid collisions.
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*/
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int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
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{
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struct inode *inode;
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@ -376,6 +387,11 @@ int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files
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inode = new_inode(s);
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if (!inode)
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return -ENOMEM;
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/*
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* because the root inode is 1, the files array must not contain an
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* entry at index 1
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*/
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inode->i_ino = 1;
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inode->i_mode = S_IFDIR | 0755;
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inode->i_uid = inode->i_gid = 0;
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inode->i_blocks = 0;
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@ -391,6 +407,13 @@ int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files
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for (i = 0; !files->name || files->name[0]; i++, files++) {
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if (!files->name)
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continue;
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/* warn if it tries to conflict with the root inode */
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if (unlikely(i == 1))
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printk(KERN_WARNING "%s: %s passed in a files array"
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"with an index of 1!\n", __func__,
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s->s_type->name);
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dentry = d_alloc_name(root, files->name);
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if (!dentry)
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goto out;
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